U.S. patent application number 11/605197 was filed with the patent office on 2007-11-29 for mst1 modulation of apoptosis in cardiac tissue and modulators of mst1 for treatment and prevention of cardiac disease.
This patent application is currently assigned to University of Medicine and Dentistry of New Jersey. Invention is credited to Junichi Sadoshima, Stephen F. Vatner.
Application Number | 20070275099 11/605197 |
Document ID | / |
Family ID | 33302797 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070275099 |
Kind Code |
A1 |
Vatner; Stephen F. ; et
al. |
November 29, 2007 |
MST1 modulation of apoptosis in cardiac tissue and modulators of
MST1 for treatment and prevention of cardiac disease
Abstract
The present invention relates to methods and agents for
treatment, amelioration and prevention of cardiac disease,
including cardiac myopathy, chronic heart failure and for
management and reduction of cardiac myocyte death which may occur
in response to ischemia/reperfusion or following myocardial
infarction or other injury to the heart. The invention relates to
methods for screening cardiotherapeutic compounds, including
compounds which modulate cardiac myocyte apoptosis, particularly
targeting Mst1 and the Mst1 pathway. The present invention further
encompasses compounds identified by such screening methods and
compositions comprising these compounds. The invention also
provides methods for treatment, amelioration and prevention of
cardiac disease comprising administering compounds or agents which
modulate, particularly inhibit, Mst1 or the Mst1 kinase pathway,
including administering a nucleic acid encoding an altered form of
Mst1, particularly a dominant negative Mst1, which acts as an
antagonist of Mst1.
Inventors: |
Vatner; Stephen F.; (New
York, NY) ; Sadoshima; Junichi; (Berkeley Heights,
NJ) |
Correspondence
Address: |
KLAUBER & JACKSON
411 HACKENSACK AVENUE
HACKENSACK
NJ
07601
US
|
Assignee: |
University of Medicine and
Dentistry of New Jersey
|
Family ID: |
33302797 |
Appl. No.: |
11/605197 |
Filed: |
November 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10683576 |
Oct 10, 2003 |
7160859 |
|
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11605197 |
Nov 28, 2006 |
|
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60418002 |
Oct 11, 2002 |
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Current U.S.
Class: |
424/718 ; 514/26;
514/44A; 514/789; 800/9 |
Current CPC
Class: |
A61K 31/704 20130101;
C12N 15/86 20130101; C12N 2710/10343 20130101; A61K 38/45 20130101;
A61K 45/06 20130101; C12Q 1/485 20130101; A61K 38/45 20130101; G01N
33/5011 20130101; A61K 48/005 20130101; A61K 2300/00 20130101; G01N
2800/32 20130101; A61P 9/00 20180101; A61K 2300/00 20130101; A61K
31/704 20130101 |
Class at
Publication: |
424/718 ;
514/026; 514/044; 514/789; 800/009 |
International
Class: |
C12Q 1/02 20060101
C12Q001/02; A01K 67/027 20060101 A01K067/027; A61K 31/00 20060101
A61K031/00; A61K 31/7034 20060101 A61K031/7034; A61K 31/7088
20060101 A61K031/7088; A61K 33/00 20060101 A61K033/00; A61P 9/00
20060101 A61P009/00; C12N 5/00 20060101 C12N005/00 |
Goverment Interests
GOVERNMENTAL SUPPORT
[0002] The research leading to the present invention was supported,
at least in part, by a grant from the National Institutes of
Health, Grant Numbers HL-59139,HL-33107, HL-33065, HL65182,
HL-65183, AG-14121, HL-69020, HL-67724 and HL-67727. Accordingly,
the Government may have certain rights in the invention.
Claims
1. A method of treating cardiac disease in a mammal comprising
administering to said mammal an effective amount of a compound or
agent that blocks or otherwise inhibits Mst1 or the Mst1
pathway.
2. The method of claim 1 wherein said compound or agent is an Mst1
inhibitor.
3. The method of claim 1 wherein the Mst1 inhibitor is selected
from the group of a dominant negative mutant of Mst1, an inhibitor
of caspase, an inhibitor of apoptosis, antisense oligonucleotide
complementary to Mst1, siRNA to Mst1 and a ribozyme directed
against Mst1.
4. The method of claim 3, wherein said Mst1 inhibitor is selected
from the group of inhibitors against Caspase 3, Chelerythrine and
Calyculin A.
5. The method of claim 1 wherein said compound or agent inhibits a
protein that phosphorylates Mst1, cleaves Mst1 to generate active
Mst1, or activates an Mst1 phosphatase.
6. The method of claim 1 wherein said cardiac disease is selected
from the group of congestive heart failure, cardiomyopathy,
including ischemic and nonischemic cardiomyopathy, coronary artery
disease, arrhythmias, fibrosis of the heart, valve defects,
atherosclerosis, and instances where facilitation of enhanced heart
function or maintenance of cardiac myocytes is desired.
7. The method of claim 1 wherein said mammal is a human.
8. A method of modulating cardiac myocyte apoptosis in a mammal
comprising administering to said mammal an effective amount of a
compound or agent that blocks or otherwise inhibits Mst1 or the
Mst1 pathway.
9. The method of claim 8 wherein the Mst1 inhibitor is selected
from the group of a dominant negative mutant of Mst1, an inhibitor
of caspase, an inhibitor of apoptosis, antisense oligonucleotide
complementary to Mst1, siRNA to Mst1 and a ribozyme directed
against Mst1.
10. A method for reducing cardiomyopathy in a mammal comprising
administering to said mammal an effective amount of an Mst1
inhibitor.
11. A method for treating cardiac disease in a mammal comprising
administering to said mammal an effective amount of a Mst1
inhibitor in combination with one or more other compound for
treatment of cardiac disease or of atherosclerosis.
12. The method of claim 11 wherein said one or more other compound
selected from the group of a beta-blocker, nitrate, calcium channel
antagonists, angiotensin-converting enzyme (ACE) inhibitors, an
anti-platelet drug, diuretics, digoxin and antilipemic agents,
agents which alter cholesterol or lipid metabolism.
13. A method for reducing the risk of cardiomyopathy or cardiac
dysfunction in a mammal wherein said mammal has suffered a
myocardial infarct or other coronary event wherein blood flow to
the heart is reduced comprising administering to said mammal an
effective amount of an Mst1 inhibitor or Mst1 pathway
inhibitor.
14. The method of claim 13 wherein the Mst1 inhibitor is selected
from the group of a dominant negative mutant of Mst1, an inhibitor
of caspase, an inhibitor of apoptosis, antisense oligonucleotide
complementary to Mst1, siRNA to Mst1 and a ribozyme directed
against Mst1.
15. A method of cardioprotection, wherein an inhibitor of Mst1 is
administered in conjunction with or following therapy with a
compound or drug which is cardiotoxic.
16. The method of claim 15 wherein said compound is a
chemotherapeutic agent, particularly an anti-cancer or anti-tumor
agent.
17. The method of claim 16 wherein said chemotherapeutic agent is
doxorubicin.
18. A method of screening for compounds which modulate cardiac
myocyte apoptosis comprising selecting compounds which inhibit Mst1
or the Mst1 pathway and performing assays with said compounds to
determine the amount or extent of cardiac myocyte apoptosis.
19. The method of claim 18 wherein selecting compounds that
modulate Mst1 or the Mst1 pathway comprises incubating Mst1 with a
candidate compound, and conducting phosphorylation assays wherein a
compound's ability to block phosphorylation of Mst1 or by Mst1 or
enhance dephosphorylation of Mst1 is determined.
20. The method of claim 18 wherein selecting compounds that
modulate Mst1 or the Mst1 pathway comprises incubating Mst1 with a
candidate compound, and conducting assays wherein a compound's
ability to block the activity of a molecule downstream of Mst1 or
which is modulated or activated by Mst1 or upon Mst1
phosphorylation or cleavage is determined.
21. The method of claim 20 wherein the molecule downstream of Mst1
is selected from the group of caspase 3, caspase 5, MBP, MAPK and
JNK.
22. A composition for modulating cardiac myocyte apoptosis
comprising an Mst1 inhibitor.
23. The composition of claim 22 wherein said Mst1 inhibitor
inhibits a protein that phosphorylates Mst1, activates an Mst1
phosphatase, inhibits a protein that cleaves and/or activates Mst1,
is an antagonist of Mst1, or is a dominant negative form Mst1.
24. A pharmaceutical composition for treatment or amelioration of
cardiac disease in a mammal comprising a therapeutically effective
amount of one or more Mst1 inhibitor and a pharmaceutically
acceptable carrier.
25. A pharmaceutical composition for treatment or amelioration of
cardiac disease in a mammal comprising a therapeutically effective
amount of a combination of one or more Mst1 inhibitor and one or
more other compounds for the treatment of cardiac disease or
atherosclerosis and a pharmaceutically acceptable carrier.
26. The pharmaceutical composition of claim 25 wherein the one or
more other compounds for the treatment of cardiac disease or
atherosclerosis are selected from the group of a beta-blocker,
nitrate, calcium channel antagonists, angiotensin-converting enzyme
(ACE) inhibitors, an anti-platelet drug, diuretics, digoxin and
antilipemic agents, agents which alter cholesterol or lipid
metabolism.
27. The pharmaceutical composition of claim 25 or 26 wherein the
cardiac disease is selected from the group of congestive heart
failure, cardiomyopathy, including ischemic and nonischemic
cardiomyopathy, coronary artery disease, arrhythmias, fibrosis of
the heart, valve defects, atherosclerosis, and instances where
facilitation of enhanced heart function or maintenance of cardiac
myocytes is desired.
28. An assay system for screening of potential compounds or agents
effective to modulate Mst1 activity of target mammalian cells by
interrupting or potentiating the Mst1 or Mst1 pathway wherein the
test compound or agent is administered to a cellular sample to
determine its effect upon the kinase activity, cleavage status or
phosphorylation status of Mst1, by comparison with a control.
29. An assay system for screening compounds or agents for the
ability to modulate the activity of Mst1, comprising: A. culturing
an observable cellular test colony inoculated with a compound or
agent; B. harvesting a supernatant from said cellular test colony;
and C. examining said supernatant for the activity of said Mst1
wherein an increase or a decrease in the activity of said Mst1
indicates the ability of a drug to modulate the activity of said
Mst1.
30. A method for treating or ameliorating cardiac disease in a
mammal comprising administering to said mammal a nucleic acid or
vector capable of encoding a dominant negative form of Mst1 such
that said dominant negative form of Mst1 is expressed in the heart
of said mammal.
31. The method of claim 30 wherein the dominant negative form is
expressed in cardiac myocytes and wherein the dominant negative
form of Mst1 antagonizes the endogenous form of Mst1 such that Mst1
is inhibited.
32. An animal model of cardiac disease, including cardiac myopathy,
comprising a transgenic animal wherein Mst1 expression or activity
is enhanced.
33. The animal model of claim 32 wherein the transgenic animal is
selected from the group of rats, mice, pigs, chicken, cows,
monkeys, rabbits, sheep and dogs.
Description
RELATED APPLICATIONS
[0001] The present application claims the benefit of the filing
date pursuant to 35 U.S.C. .sctn. 119 of provisional application
Ser. No. 60/418,002, filed Oct. 11, 2003, which is incorporated
herein by reference in its entirety.
FIELD OF THE INVENTION
[0003] The present invention relates to methods and agents for
treatment, amelioration and prevention of cardiac disease,
including cardiac myopathy, chronic heart failure and for
management and reduction of cardiac myocyte death which may occur
in response to ischemia/reperfusion or following myocardial
infarction or other injury to the heart. The invention relates to
methods for screening cardiotherapeutic compounds, including
compounds which modulate cardiac myocyte apoptosis, particularly
targeting Mst1 and the Mst1 pathway. The present invention further
encompasses compounds identified by such screening methods and
compositions comprising these compounds.
BACKGROUND OF THE INVENTION
[0004] Intensive studies in the past decade have shown that cardiac
myocyte death, which has characteristics of apoptosis, occurs in
response to ischemia/reperfusion (I/R) and during cardiac
remodeling after myocardial infarction (1-9). Although
controversies still exist regarding the occurrence of apoptosis-vs
oncosis in the ischemic heart (10,11), it seems established that
the signaling mechanisms promoting myocyte cell death, including
caspases, are activated by I/R and in cardiomyopathy (12-16)
(reviewed in 47). Recent evidence suggests that myocyte
proliferation could take place in response to the loss of cardiac
myocyte after myocardial infarction (17). However, considering the
limited capacity of terminally differentiated cardiac myocytes for
proliferation, it is important to understand how these cell death
promoting signaling mechanisms are activated by I/R and in
myopathic hearts in order to establish interventions efficiently
preventing the cell loss in various stages of heart diseases (10).
It has been shown that intracellular stress-responsive protein
kinases, including JNKs and p38-MAPKs, are activated by I/R in the
heart (18-23). Although these kinases are likely to affect both
cell death and cell survival, the roles of the stress-responsive
protein kinases (SRPKs) in cardiac myocyte apoptosis are not fully
understood. Furthermore, the SRPK selectively promoting cardiac
myocyte apoptosis has not been identified in vivo.
[0005] Mst1 (mammalian sterile 20-like kinase-1) is a ubiquitously
expressed serine/threonine kinase (24,25), which belongs to a
mammalian sterile 20 (STE 20)-like kinase family consisting of
Pak1, Mst1, Mst2, Khs, Gck, Sok1, Nik, Hpk1 and Sps1 (26,27).
Increasing lines of evidence suggest that Mst1 and other STE20-like
family kinases play an important role in mediating apoptosis
(reviewed in (27)). Mst 1 is activated by some pro-apoptotic
stimuli in fibroblastic and lymphocytic cell lines. However,
stimuli shown to activate Mst1 are generally limited to
non-physiological stresses, including genotoxic compounds and
extreme heat shock (25,28-31). Mst1 can be an efficient mediator of
apoptosis because it is cleaved by caspases and this cleavage
increases kinase activities of Mst1, which in turn activates
caspase 3 (32), thereby constituting a powerful amplification loop
of apoptotic response (33). Importantly, however, whether or not
activation of Mst1 is required for in vivo cell death in response
to clinically relevant pathologic insults has not been determined
in any organs, including the heart.
[0006] Despite a growing understanding that apoptosis plays a
physiological role and potentially pathological role in the heart
there still exists a significant need in the art for methods and
agents for treatment, amelioration and prevention of cardiac
disease, including cardiac myopathy, chronic heart failure and for
management and reduction of cardiac myocyte death which may occur
in response to ischemia/reperfusion or following myocardial
infarction or other injury to the heart.
[0007] The citation of references herein shall not be construed as
an admission that such is prior art to the present invention.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, it has been
recognized and demonstrated that stimulation or enhanced expression
of Mst1 causes cardiac myocyte apoptosis and dilated
cardiomyopathy, without any compensatory cardiac myocyte
hypertrophy. In addition, specific inhibition of endogenous Mst1,
for instance by dominant negative Mst1, inhibits cardiac myocyte
apoptosis and myocardial infarction in response to
ischemia/reperfusion (I/R). Inhibition of endogenous Mst1 also
inhibits the negative cardiac effects of cardiotoxic drugs,
including doxorubicin. In addition, on inhibition of endogenous
Mst1, the cardiac dilation and cardiac dysfunction following
myocardial infarction are significantly reduced. Thus, Mst1 plays
an essential role in mediating apoptosis by clinically relevant
pathologic stimuli in the heart and represents an important
therapeutic target in ischemic heart diseases.
[0009] The invention relates to the application and use of
modulators, including inhibitors, of Mst1 to treat or prevent heart
disease. The invention relates to the use of modulators,
particularly inhibitors, of the Mst1 kinase for amelioration,
treatment or prevention of cardiac disease, particularly wherein it
is desired to reduce or control cardiac myocyte apoptosis,
including in congestive heart failure, cardiomyopathy, including
ischemic and nonischemic cardiomyopathy, coronary artery disease,
arrhythmias, fibrosis of the heart, valve defects, and
atherosclerosis, as well as in instances where facilitation of
enhanced heart function or maintenance of cardiac myocytes is
desired.
[0010] In a particular aspect, the invention provides methods of
modulating the apoptosis of cardiac myocytes and cardiac myopathy
in a mammal by administration of a compound or agent that blocks or
otherwise inhibits Mst1 or the Mst1 pathway. In one aspect, a
method for modulating the apoptosis of cardiac myocytes and cardiac
myopathy is provided whereby an effective amount of an inhibitor of
Mst1 is administered.
[0011] In a further aspect, the invention provides a method for
treating cardiac disease in a mammal comprising administering to
said mammal an effective amount of an Mst1 inhibitor. In a
particular aspect, the invention further provides a method for
treating a cardiac disease or dysfunction selected from the group
of congestive heart failure, cardiomyopathy, including ischemic and
nonischemic cardiomyopathy, coronary artery disease, arrhythmias,
fibrosis of the heart, valve defects, and atherosclerosis in a
mammal comprising administering to said mammal an effective amount
of an Mst1 inhibitor. In a still further aspect a method is
provided for reducing the risk of cardiomyopathy or dysfunction in
a mammal after said mammal has suffered a myocardial infarct or
other coronary event wherein blood flow to the heart is compromised
or significantly reduced comprising administering to said mammal an
effective amount of an Mst1 inhibitor or Mst1 pathway
inhibitor.
[0012] In a further aspect, the invention provides a method of
cardioprotection, wherein an inhibitor of Mst1 is administered in
conjunction with or following therapy with a compound or drug which
is cardiotoxic or has potential to be cardiotoxic. In this method,
an Mst1 modulator blocks or otherwise reduces the cardiotoxic
effects of a drug or compound. In a particular embodiment, the drug
or compound is a chemotherapeutic agent, particularly an
anti-cancer agent, including but not limited to doxorubicin. In a
further aspect, administration of the Mst1 modulator enables
chemotherapeutic, particularly anti-cancer or anti-tumor compounds,
treatment without significant cardiotoxic effects or permits
prolonged chemotherapy or administration of higher concentrations
or amounts of a potentially cardiotoxic drug.
[0013] In a further aspect, the invention provides a method for
treating cardiac disease in a mammal comprising administering to
said mammal an effective amount of an Mst1 inhibitor in combination
with one or more other compounds for the treatment of heart
disease, including but not limited to congestive heart failure,
cardiomyopathy, including ischemic and nonischemic cardiomyopathy,
coronary artery disease, arrhythmias, fibrosis of the heart, valve
defects, and atherosclerosis. In particular, an effective amount of
an Mst1 inhibitor may be used in combination with one or more
compound for treatment of cardiac disease or of atherosclerosis,
including but not limited to a beta-blocker, nitrate, calcium
channel antagonists, angiotensin-converting enzyme (ACE)
inhibitors, an anti-platelet drug, diuretics, digoxin and
antilipemic agents, agents which alter cholesterol or lipid
metabolism. Further examples of such or treatmantilipemic agents
include, but are not limited to the statins, such as Lovastatin
(Mevacor.RTM.), Atorvastatin (Lipitor.RTM.), Simvastatin
(Zocor.RTM.), Cerivastatin (Baycol.RTM.), Pravastatin
(Pravacol.RTM.), Fluvastatin (Lescol.RTM.) and Rosuvastatin; as
well as other classes of compounds including cholesterol ester
transfer protein inhibitors; cholesterol adsorption inhibitors
(e.g., Ezetimide.RTM.); fibrates (e.g., Gemfibrozil.RTM.);
nicotinic acid (e.g., niacin and analogs, Niaspan.RTM.); bile acid
reuptake inhibitors; and modulators of nuclear hormone receptors
such as PPARa, PPARb, PPARg, LXRa, LXRb, FXR, RORa and SHP.
[0014] The object of the invention extends to the provision of
methods for screening for cardiotherapeutic compounds, particularly
compounds which modulate cardiac myocytes, particularly apoptosis
of cardiac myocytes, by using Mst1 or a member of the Mst1 pathway.
In a particular object, methods are provided for screening
compounds which modulate cardiac myocytes, by modulating Mst1, Mst1
kinase activity, or the Mst1 pathway, for instance by modulating
caspase which activates Mst1 by caspase-mediated cleavage of the
C-terminal inhibitory domain. In addition, the present invention
encompasses compounds that are identified by the screening methods
disclosed herein. Further provided are methods and compositions for
modulating cardiac myocytes and thereby modulating cardiac disease
and cardiac function.
[0015] A method of the invention involves screening
cardiotherapeutic compounds and includes the steps of selecting
compounds that modulate Mst1 or some portion of the Mst1 pathway,
and performing assays with said compounds. The method of screening
of the present invention may also include the step of identifying
compounds that lead to reduction of cardiac myocyte apoptosis, or
alternatively, to a decrease in levels or activity of Mst1.
Selecting compounds that modulate Mst1 or the Mst1 pathway may
involve different assays, such as, e.g., phosphorylation assays
wherein a compound's ability to block phosphorylation of or by Mst1
or enhance dephosphorylation of Mst1 or a Mst1 target is determined
directly or wherein the activity of a molecule downstream of Mst1
is determined. For instance, the phosphorylation of the Mst1 target
myelin basic protein (MBP) can be assayed, including by incubation
with labeled phosphate (e.g. .gamma.P.sup.32) and determining
whether MBP is labeled. Compounds for screening may be selected
from various libraries of small molecular weight compounds,
peptides, or alternatively may be selected by homology modeling,
computational modeling, and screening phage display libraries.
[0016] The invention thus includes an assay system for screening of
potential drugs effective to modulate Mst1 activity of cardiac
cells by interrupting or potentiating Mst1 or the Mst1 pathway. In
one instance, the test drug could be administered to a cellular
sample to determine its effect upon the kinase activity or
phosphorylation status of Mst1 or an Mst1 target, by comparison
with a control.
[0017] The present invention also includes compositions for
treating or ameliorating cardiac disease, particularly for
modulating apoptosis of cardiac myocytes. These compositions may
comprise compounds identified by the screening methods disclosed
herein. Thus, these compositions may be used to cardiac diseases or
conditions where cardiac function or efficiency is compromised.
[0018] It is a thus an object of the present invention to provide
pharmaceutical compositions for use in therapeutic methods for
modulation of cardiac disease which comprise an Mst1 inhibitor. In
a further aspect, the invention provides pharmaceutical
compositions for use in therapeutic methods for modulation of
cardiac disease which comprise an Mst1 inhibitor and one or more
compounds for the treatment of heart disease, including but not
limited to congestive heart failure, cardiomyopathy, including
ischemic and nonischemic cardiomyopathy, coronary artery disease,
arrhythmias, fibrosis of the heart, valve defects, and
atherosclerosis. In particular, an effective amount of an Mst1
inhibitor may be used in combination with one or more compound for
treatment of cardiac disease or of atherosclerosis, including but
not limited to a beta-blocker, nitrate, calcium channel
antagonists, angiotensin-converting enzyme (ACE) inhibitors, an
anti-platelet drug, diuretics, digoxin and antilipemic agents,
agents which alter cholesterol or lipid metabolism.
[0019] In a particular aspect of the invention, the Mst1 inhibitor
is a mutant Mst1 which acts as an antagonist of Mst1, particularly
a dominant negative Mst1. In one such example, the Mst1 mutant is
Mst1, (K59R). In a method of the invention, cardiac myocytes are
transduced, transfected or infected with nucleic acid or vector
containing nucleic acid encoding a mutant Mst1 which acts as a
dominant negative to antagonize wild type and endogenous Mst1. By
expression of dominant negative Mst1 in cardiac myocytes, apoptosis
is blocked or reduced and cardiac disease is thereby treated or
ameliorated.
[0020] The DNA sequences of Mst1 of use in the present invention or
portions thereof, may be prepared with a variety of known vectors,
particularly vectors capable of expressing such DNAs in animal
cells, particularly in human cells. In one such embodiment, the
vectors include those suitable for delivery to human cells,
particularly to cardiac or heart cells, such as myocytes. Examples
of such vectors include viral vectors such as adenovirus, or naked
DNA vectors, for instance for injection or delivery to the heart
wherein the DNA is then expressed. The present invention also
includes the preparation of plasmids or viruses including such
vectors, and the use of the DNA sequences to construct vectors
expressing antisense RNA, small interfering RNAs or ribozymes which
would attack or interfere with the mRNAs of any or all of the DNA
sequences encoding native or endogenous Mst1. Correspondingly, the
preparation of antisense RNA, siRNAs and ribozymes are included
herein.
[0021] In a further object, the invention provides animal models,
including transgenic models, of cardiac disease and cardiac
myopathy. Such animal models include transgenic animals expressing
enhanced amounts of Mst1 or altered Mst1 (including wherein Mst1 is
substantially more active or constitutively active). These animals
are useful in studies of cardiac disease, including for the
screening and assessment of potential cardiotherapeutic compounds.
These animals include but are not limited to rats, mice, pigs,
chicken, cows, monkeys, rabbits, sheep and dogs.
[0022] Other objects and advantages will become apparent to those
skilled in the art from a review of the following description which
proceeds with reference to the following illustrative drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIGS. 1A, 1B, 1C, 1D and 1E depict Mst1 activity assessed on
treatment of cardiac myocytes with chelerythrine (Chele) or
calyculin A. (A) Cardiac myocytes were treated with indicated
concentrations of chelerythrine for 1 h. Cell lysates were
subjected to in-gel myelin basic protein (MBP) kinase assay as well
as immunoblotting with anti-cleaved caspase-3 antibody. Results are
representative of more than five experiments. (B) Cardiac myocytes
were treated with chelerythrine (Chele). In the right panel,
myocytes were transduced with either control virus or adenovirus
harboring XIAP 48 hours before Chele application. Cell lysates were
subjected with immune complex in-gel MBP kinase assays, using
anti-Mst1 polyclonal antibody (pAb-15). The activity of cleaved
Mst1 is shown. (C) Cardiac myocytes were treated with Chele for the
indicated durations. Immunoblot analyses were conducted by using
anti-Mst1 monoclonal antibody (upper panel) and anti-Mst1
polyclonal antibody (lower panel), which detects the full length
form and cleaved form (amino-terminal half) of Mst1, respectively.
(D) Cardiac myocytes were subjected to 8h of hypoxia alone (H) or
8h hypoxia plus 12 h of reoxygenation (H/R). In-gel MBP kinase
assays were performed. Control, C. Upper arrow indicates the full
length form of Mst1, while lower arrow cleaved form of Mst1. (E)
Cardiac myocytes were treated with vehicle (lane 1) or calyculin A
(1 .mu.M, lane 2). In-gel MBP kinase assays were performed. Arrow
indicates the full length form of Mst1.
[0024] FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G. (A to G) Cardiac
myocytes were transduced with adenovirus harboring either wild type
Mst1 (AdX-Mst1), Mst1 (K59R) (AdX-Mst1(K59R)) or control adenovirus
(Ad5 .beta.gal) at indicated concentrations. Myocytes were
harvested 48 h after transduction. Some myocytes (C and F) were
treated with a caspase-3 inhibitor (DEVD-CHO, 100 .quadrature.M).
(A and B) Immunoblot analyses were performed by using anti-Mst1
polyclonal antibody. MOI, multiplicity of infection. Cont, control
where no virus was applied. (C) In-gel MBP assays were performed.
(D) The effect of adenovirus transduction (30 MOI) upon the
morphology of cardiac myocytes is shown. Note that cell death with
shrinkage is observed in AdX-Mst1 transduced cardiac myocytes. (E
and F) Cytoplasmic accumulation of mono- and oligo-nucleosomes, a
sensitive indicator of DNA fragmentation by apoptosis, was
quantitated by Cell Death ELISA Plus. n=3 (F) (G) Activation
caspase-3 was determined by immunoblot analyses with anti-cleaved
caspase-3 antibody. n=3.
[0025] FIG. 3 depicts the effect of dominant negative Mst1 upon
chelerythrine-induced cardiac myocyte apoptosis. Cardiac myocytes
were transduced with er control virus or adenovirus harboring
dominant negative Mst1 (Mst1(K59R)). Forty-eight hours after
transduction, cardiac myocytes were treated with chelerythrine (10
.mu.M) for 1 h and cytoplasmic accumulation of mono- and
oligo-nucleosome was quantitated. n=3.
[0026] FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, and 4I. (A) Immunoblot
analyses of the heart homogenates with anti-myc antibody. (B)
Tissue homogenates were prepared from various organs of Tg-Mst1.
Immunoblot analyses were performed with anti-myc antibody. (C)
Heart homogenates were prepared from Tg-Mst1 or non-transgenic
control mice (Ntg). In-gel MBP kinase assays were performed. (D)
Gross appearance and a transverse section of the hearts obtained
from Tg-Mst1 and NTg. Hematoxylin Eosin staining was performed (3
months old). (E) A photograph of the liver isolated from Tg-Mst1
and the littermate NTg (3 months old). (F) Picric acid sirius red
staining of heart sections obtained from Tg-Mst1 and NTg (1.5 month
old). (G) LV cardiac myocyte cross sectional area was obtained from
Tg-Mst1 and NTg as described in the Method section. Seven Tg-Mst1
and 4 NTg mice were used for the analysis. (H) Heart homogenates
were prepared from Tg-Mst1 and NTg. (I) Immunoblot analyses were
performed by using anti-cleaved caspase-3 antibody. n=3.
[0027] FIG. 5 depicts myocyte length and contractile (%
contraction) and relaxation (TR 70%: time for 70% relengthening)
function. Myocyte length was significantly reduced, p<0.05, in
myocytes from Tg-Mst1 (n=4, 111 cells) compared with WT (n=4, 129
cells). There was no change in contractile and relaxation
function.
[0028] FIGS. 6A, 6B, 6C, 6D and 6E depicts (A) Immunoblot analyses
of the heart homogenates with anti-myc antibody. In (B)-(E),
Tg-DN-Mst1 or non-transgenic control mice (NTg) were subjected to
20 min ischemia and 24 h reperfusion or sham operation. (B) The
heart homogenates (100 .mu.g) obtained from ischemic (I) and
non-ischemic (N) areas of the left ventricle (LV) or from intact LV
of the sham operated mice were subjected to in gel myelin basic
protein (MBP) kinase assays. Ischemia/reperfusion (I/R) increased
kinase activities of Mst1 in the ischemic area of NTg mice, while
activation of Mst1 by I/R was completely abolished in Tg-DN-Mst1.
(C) The effect of I/R upon the extent of LV myocardial infarction
(MI) in Tg-DN-Mst1 and NTg control mice. The MI area/area at risk
(AAR) was determined as described in the Method section. Note that
MI area/AAR was significantly smaller in Tg-DN-Mst1 compared with
that in NTg. (D) LV tissue sections were subjected to TUNEL
staining and DAPI staining. n=11. (E) Genomic DNA was isolated from
non-ischemic (N) and ischemic (I) areas and DNA laddering assays
were performed. The extent of DNA laddering in response to I/R was
significantly smaller in Tg-DN-Mst1 compared with that in NTg.
n=3.
[0029] FIGS. 7A, 7B, 7C and 7D depicts (A) Cardiac myocytes were
transduced with either control virus (Cont) or AdX-Mst1(Mst1) at 10
MOI for 48 h. As positive control, myocytes were treated with
chelerythrine (Chele, 10 .mu.M) for 1 h. The mitochondria-free
cytosolic fraction was obtained. Western blot analysis was
performed using anti-cytochrome c antibody (Pharmingen, San Diego,
Calif.). Cytochrome c oxidase IV immunoreactivity was negligible in
these samples. Chele caused a release of cytochrome c to the
cytosolic fraction. Expression of Mst1 increased release of
cytochrome c. n=3. (B,C) Cardiac myocytes were transduced with
either control virus or AdX-Mst1(Mst1) at indicated MOIs for 48 h.
(upper) Immunoblot analyses were conducted using anti-phospho
p38-MAPK antibody (B) or anti-phospho JNK antibody (C). (lower) The
filters were re-probed with anti-p38-MAPK antibody (B) or anti-JNK1
antibody (C). In b and c, Similar results were obtained in 4
experiments. (D) Cardiac myocytes were transduced with either
control virus or AdX-DN-Mst1 virus. Myocytes were then stimulated
with or without chelerythrine (Chele, 10 .mu.M) for 60 min. Myocyte
lysates were subjected to immunoblot analysis using anti-phospho
p38-MAPK antibody. The filter was re-probed with anti-p38-MAPK
antibody. Similar results were obtained in 3 experiments.
[0030] FIGS. 8A and 8B depicts mRNA expression of PGC-1.alpha. and
.beta. is downregulated in Tg-Mst1 (PGC-1 is a nuclear
transcription co-factor, which plays an important role in
regulating expression of nuclear encoded mitochondrial genes).
RT-PCR results are shown. Each band in the gel shown in (A)
represents RNA combined from 2 separate hearts. Mice were
approximately 2 months old. Data represents a single experiment.
The relative RNA levels are graphed in (B).
[0031] FIGS. 9A and 9B depicts that protein expression of
cytochrome c oxidase is downregulated in Tg-Mst1 animals. Western
blots of protein from nontransgenic (N) and transgenic (T)
individual animals are shown in (A) for cytochrome c oxidase VIIa
(COX VIIa), IV (COX IV) and Vb (COX Vb). Relative protein
expression for each COX is graphed in (B). Data are mean
.+-.SEM.
[0032] FIG. 10 depicts neonatal rat cardiac myocytes after 6 hour
stimulation with Doxorubicin (Doxo). Control myocytes show no
evidence of shrinkage, vacuolization, or pyknosis. After 6 hours of
Doxo induction, myocytes show a dose dependent cell shrinkage and
nuclear pyknosis.
[0033] FIG. 11 ELISA shows a reduction of mono- and
oligo-nucleosome content in the Adx-Dn-Mst1 treated group after 6
hrs of Doxo stimulation. OD 405, 5 moi of control virus (Lac Z) and
DN-Mst1 virus (DNV) respectively. Most likely the slight decrease
in the DNV Doxo 1 mM lane is due to increased necrosis of cells in
the wells at this dose.
[0034] FIG. 12 depicts a cell death ELISA which again shows a trend
in the reduction of mono- and oligo-nucleosome content in the
Adx-Dn-Mst1 treated group after 6 hrs of Doxo stimulation. OD 405
with 10 moi of Lac Z and DN-Mst1 AdX respectively.
[0035] FIG. 13 provides a Western blot depicting cleavage of
caspase-3 in the presence of Doxo at the 6 and 24 hour time points.
Data suggest that Doxo treatment activates caspase-3 in a time
dependent manner.
[0036] FIG. 14 shows a stripped membrane of the previous (FIG. 13)
CC-3 antibody reprobed with CC-9 antibody. This western blot also
depicts cleavage of caspase-9 in the presence of Doxo at the 6 and
24 hour time points, with the stronger band appearing at the 24
hour time point. Data suggest that Doxo treatment activates
caspase-9 in a time dependent manner.
[0037] FIG. 15 provides an in gel kinase assay depicting activation
of the full length (61kD) and cleaved (34 kD) forms of Mst1 after 6
hr Doxo stimulation of cardiac myocytes. Myelin basic protein is a
major substrate that binds Mst1 during phosphorylation.
[0038] FIG. 16 depicts a Western blot with MST1 antibody after 6
hrs of stimulation of neonatal cardiac myocyte culture with Doxo,
showing cleaved Mst-1 at the 0.5 mM dose. Doxo activates cleaved
Mst1 but in the presence of DN-Mst1 this reaction is
suppressed.
[0039] FIG. 17 depicts an immunoblot of cardiac myocytes exposed to
10 moi of either .beta.gal (Lac Z) or DN-Mst1 adenovirus prior to
all myocytes being exposed to 6 hr of Doxo stimulation. In the
presence of the DN virus, there is no activation of cleaved caspase
-3 when compared to .beta.gal and uninfected myocytes stimulated
with Doxo 0.5 mM.
[0040] FIG. 18 compares 10 moi control virus (.beta.gal) and 10 moi
Adx-DN-Mst1 at baseline and after 6 hrs of stimulation with Doxo.
Cell death and shrinkage are noted in the control virus specimen
treated with Doxo but not in the Adx-DN-Mst1 treated specimen. This
suggests that DN-Mst1 inhibits cardiac myocyte apoptosis by
Doxo.
[0041] FIG. 19 compares control and dominant negative transgenic
mice with and without Doxo injection. Dominant negative transgenic
mice receiving the Doxo injection maintain ejection fraction post
Doxo injection when compared to their non-transgenic litermates.
This suggests that Dn-Mst1 confers a protective effect, possibly
inhibiting apoptosis so contractility is maintained.
[0042] FIG. 20 compares control and dominant negative transgenic
mice with and without Doxo injection. Dominant negative transgenic
mice receiving the Doxo injection maintain their % fractional
shortening post Doxo injection when compared to their
non-transgenic litermates. This suggests that Dn-Mst1 confers a
protective effect, possibly by inhibiting apoptosis to maintain
contractility.
[0043] FIG. 21 compares the body weights of the non-transgenic an
DN-Mst1 mice pre and post injections of Doxo and normal saline. The
significant loss of weight between the NTG pre and DN-TG post Doxo
injection mice is most likely due to the well known side effect of
anorexia that accompanies Doxo treatment.
[0044] FIG. 22 compares the LVEDD of the non-transgenic and DN-Mst1
mice pre and post Doxo/normal saline treatment. The p value is not
significant.
[0045] FIGS. 23A and 23B depict trangsenic Mst1 and nontransgenic
animals 4 weeks after left coronary artery ligation to generate a
myocardial infarction (MI) in vivo. (A) indicates that a similar
size of myocardial infarction was created by ligation of the left
coronary artery in non-transgenic (NTG) and transgenic (Tg-DN-Mst1)
mice. LVEDD (B) and LVEF (B) were measured in sham operated and MI
mice.
DETAILED DESCRIPTION
[0046] The studies provided herein assessed whether or not Mst1
plays an essential role in mediating apoptosis in cardiac myocytes,
by using both cultured cardiac myocytes in vitro and transgenic
mouse models in vivo. The results demonstrate that Mst1 is
activated not only by genotoxic compounds but also by clinically
relevant pathologic insults in the heart. Stimulation of or
enhanced expression of Mst1 causes cardiac myocyte apoptosis and
dilated cardiomyopathy, without any compensatory cardiac myocyte
hypertrophy. In addition, specific inhibition of endogenous Mst1 by
dominant negative Mst1 inhibits cardiac myocyte apoptosis and
myocardial infarction in response to ischemia/reperfusion (I/R).
Inhibition of endogenous Mst1 also inhibits the negative cardiac
effects of cardiotoxic drugs, as demonstrated in blockage of
doxorubicin-induced cardiomyopathy. In addition, on inhibition of
endogenous Mst1, the cardiac dilation and cardiac dysfunction
following myocardial infarction are significantly reduced. Thus,
Mst1 plays an essential role in mediating apoptosis by clinically
relevant pathologic stimuli in the heart and represents an
important therapeutic target in ischemic heart diseases.
[0047] In accordance with the present invention there may be
employed conventional molecular biology, microbiology, and
recombinant DNA techniques within the skill of the art. Such
techniques are explained fully in the literature. See, e.g.,
Sambrook et al, "Molecular Cloning: A Laboratory Manual" (1989);
"Current Protocols in Molecular Biology" Volumes I-III [Ausubel, R.
M., ed. (1994)]; "Cell Biology: A Laboratory Handbook" Volumes
I-III [J. E. Celis, ed. (1994))]; "Current Protocols in Immunology"
Volumes I-III [Coligan, J. E., ed. (1994)]; "Oligonucleotide
Synthesis" (M. J. Gait ed. 1984); "Nucleic Acid Hybridization" [B.
D. Hames & S. J. Higgins eds. (1985)]; "Transcription And
Translation" [B. D. Hames & S. J. Higgins, eds. (1984)];
"Animal Cell Culture" [R. I. Freshney, ed. (1986)]; "Immobilized
Cells And Enzymes" [IRL Press, (1986)]; B. Perbal, "A Practical
Guide To Molecular Cloning" (1984).
[0048] Therefore, if appearing herein, the following terms shall
have the definitions set out below.
[0049] The terms "mammalian sterile 20-like kinase-1", "Mst1" and
any variants not specifically listed, may be used herein
interchangeably, and as used throughout the present application and
claims refer to proteinaceous material including single or multiple
proteins, and extends to those proteins having the profile of
activities set forth herein and in the Claims. Accordingly,
proteins displaying substantially equivalent or altered activity
are likewise contemplated. These modifications may be deliberate,
for example, such as modifications obtained through site directed
mutagenesis, or may be accidental, such as those obtained through
mutations in hosts that are producers of the complex or its named
subunits. Also, the terms "mammalian sterile 20-like kinase-1",
"Mst1" and "Mst1(s)" are intended to include within their scope
proteins specifically recited herein as well as all substantially
homologous analogs and allelic variations. The protein and encoding
nucleic acid sequences of Mst1 are publicly known and described
including in the Genbank database.
[0050] The amino acid residues described herein are preferred to be
in the "L" isomeric form. However, residues in the "D" isomeric
form can be substituted for any L-amino acid residue, as long as
the desired functional property is retained by the polypeptide.
NH.sub.2 refers to the free amino group present at the amino
terminus of a polypeptide. COOH refers to the free carboxy group
present at the carboxy terminus of a polypeptide. In keeping with
standard polypeptide nomenclature, J. Biol. Chem., 243:3552-59
(1969), abbreviations for amino acid residues (for example for
tyrosine, the 1-abbreviation Y, or the 3-letter abbreviation Tyr)
are as well known and recognized in the art.
[0051] A "replicon" is any genetic element (e.g., plasmid,
chromosome, virus) that functions as an autonomous unit of DNA
replication in vivo; i.e., capable of replication under its own
control.
[0052] A "vector" is a replicon, such as plasmid, phage or cosmid,
to which another DNA segment may be attached so as to bring about
the replication of the attached segment.
[0053] A "DNA molecule" refers to the polymeric form of
deoxyribonucleotides (adenine, guanine, thymine, or cytosine) in
its either single stranded form, or a double-stranded helix. This
term refers only to the primary and secondary structure of the
molecule, and does not limit it to any particular tertiary forms.
Thus, this term includes double-stranded DNA found, inter alia, in
linear DNA molecules (e.g., restriction fragments), viruses,
plasmids, and chromosomes. In discussing the structure of
particular double-stranded DNA molecules, sequences may be
described herein according to the normal convention of giving only
the sequence in the 5' to 3' direction along the nontranscribed
strand of DNA (i.e., the strand having a sequence homologous to the
mRNA).
[0054] A DNA "coding sequence" is a double-stranded DNA sequence
which is transcribed and translated into a polypeptide in vivo when
placed under the control of appropriate regulatory sequences. The
boundaries of the coding sequence are determined by a start codon
at the 5' (amino) terminus and a translation stop codon at the 3'
(carboxyl) terminus. A coding sequence can include, but is not
limited to, prokaryotic sequences, cDNA from eukaryotic mRNA,
genomic DNA sequences from eukaryotic (e.g., mammalian) DNA, and
even synthetic DNA sequences. A polyadenylation signal and
transcription termination sequence will usually be located 3' to
the coding sequence. Transcriptional and translational control
sequences are DNA regulatory sequences, such as promoters,
enhancers, polyadenylation signals, terminators, and the like, that
provide for the expression of a coding sequence in a host cell.
[0055] An "expression control sequence" is a DNA sequence that
controls and regulates the transcription and translation of another
DNA sequence. A coding sequence is "under the control" of
transcriptional and translational control sequences in a cell when
RNA polymerase transcribes the coding sequence into mRNA, which is
then translated into the protein encoded by the coding
sequence.
[0056] The term "oligonucleotide," as used herein in referring to
the probe of the present invention, is defined as a molecule
comprised of two or more ribonucleotides, preferably more than
three. Its exact size will depend upon many factors which, in turn,
depend upon the ultimate function and use of the
oligonucleotide.
[0057] The term "primer" as used herein refers to an
oligonucleotide, whether occurring naturally as in a purified
restriction digest or produced synthetically, which is capable of
acting as a point of initiation of synthesis when placed under
conditions in which synthesis of a primer extension product, which
is complementary to a nucleic acid strand, is induced, i.e., in the
presence of nucleotides and an inducing agent such as a DNA
polymerase and at a suitable temperature and pH. The primer may be
either single-stranded or double-stranded and must be sufficiently
long to prime the synthesis of the desired extension product in the
presence of the inducing agent. The exact length of the primer will
depend upon many factors, including temperature, source of primer
and use of the method. For example, for diagnostic applications,
depending on the complexity of the target sequence, the
oligonucleotide primer typically contains 15-25 or more
nucleotides, although it may contain fewer nucleotides.
[0058] The primers or oligonucleotides herein are selected to be
"substantially" complementary to different strands of a particular
target DNA sequence. This means that the primers must be
sufficiently complementary to hybridize with their respective
strands. Therefore, the primer sequence need not reflect the exact
sequence of the template. For example, a non-complementary
nucleotide fragment may be attached to the 5' end of the primer,
with the remainder of the primer sequence being complementary to
the strand. Alternatively, non-complementary bases or longer
sequences can be interspersed into the primer, provided that the
primer sequence has sufficient complementarity with the sequence of
the strand to hybridize therewith and thereby form the template for
the synthesis of the extension product.
[0059] As used herein, the terms "restriction endonucleases" and
"restriction enzymes" refer to bacterial enzymes, each of which cut
double-stranded DNA at or near a specific nucleotide sequence.
[0060] A cell has been "transformed" by exogenous or heterologous
DNA when such DNA has been introduced inside the cell. The
transforming DNA may or may not be integrated (covalently linked)
into chromosomal DNA making up the genome of the cell. In
prokaryotes, yeast, and mammalian cells for example, the
transforming DNA may be maintained on an episomal element such as a
plasmid. With respect to eukaryotic cells, a stably transformed
cell is one in which the transforming DNA has become integrated
into a chromosome so that it is inherited by daughter cells through
chromosome replication. This stability is demonstrated by the
ability of the eukaryotic cell to establish cell lines or clones
comprised of a population of daughter cells containing the
transforming DNA. A "clone" is a population of cells derived from a
single cell or common ancestor by mitosis. A "cell line" is a clone
of a primary cell that is capable of stable growth in vitro for
many generations.
[0061] Two DNA sequences are "substantially homologous" when at
least about 75% (preferably at least about 80%, and most preferably
at least about 90 or 95%) of the nucleotides match over the defined
length of the DNA sequences. Sequences that are substantially
homologous can be identified by comparing the sequences using
standard software available in sequence data banks, or in a
Southern hybridization experiment under, for example, stringent
conditions as defined for that particular system. Defining
appropriate hybridization conditions is within the skill of the
art. See, e.g., Maniatis et al., supra; DNA Cloning, Vols. I &
II, supra; Nucleic Acid Hybridization, supra. It should be
appreciated that also within the scope of the present invention are
DNA sequences encoding which code for a having the same amino acid
sequence as SEQ ID NO:, but which are degenerate to SEQ ID NO:. By
"degenerate to" is meant that a different three-letter codon is
used to specify a particular amino acid. It is well known in the
art that specific and particular codons can be used interchangeably
to code for each specific amino acid.
[0062] Mutations can be made in Mst1 or the compounds of the
present invention such that a particular codon is changed to a
codon which codes for a different amino acid. Such a mutation is
generally made by making the fewest nucleotide changes possible. A
substitution mutation of this sort can be made to change an amino
acid in the resulting protein in a non-conservative manner (i.e.,
by changing the codon from an amino acid belonging to a grouping of
amino acids having a particular size or characteristic to an amino
acid belonging to another grouping) or in a conservative manner
(i.e., by changing the codon from an amino acid belonging to a
grouping of amino acids having a particular size or characteristic
to an amino acid belonging to the same grouping). Such a
conservative change generally leads to less change in the structure
and function of the resulting protein. A non-conservative change is
more likely to alter the structure, activity or function of the
resulting protein. The present invention should be considered to
include sequences containing conservative changes which do not
significantly alter the activity or binding characteristics of the
resulting protein.
[0063] The following is one example of various groupings of amino
acids:
Amino Acids with Nonpolar R Groups
Alanine, Valine, Leucine, Isoleucine, Proline, Phenylalanine,
Tryptophan Methionine
Amino Acids with Uncharged Polar R Groups
Glycine, Serine, Threonine, Cysteine, Tyrosine, Asparagine,
Glutamine
Amino Acids with Charged Polar R Groups (Negatively Charged at Ph
6.0)
Aspartic acid, Glutamic acid
Basic Amino Acids (Positively Charged at pH 6.0)
Lysine, Arginine, Histidine (at pH 6.0)
Another grouping may be those amino acids with phenyl groups:
Phenylalanine, Tryptophan, Tyrosine
[0064] Another grouping may be according to molecular weight (i.e.,
size of R groups): TABLE-US-00001 Glycine 75 Alanine 89 Serine 105
Proline 115 Valine 117 Threonine 119 Cysteine 121 Leucine 131
Isoleucine 131 Asparagine 132 Aspartic acid 133 Glutamine 146
Lysine 146 Glutamic acid 147 Methionine 149 Histidine (at pH 6.0)
155 Phenylalanine 165 Arginine 174 Tyrosine 181 Tryptophan 204
[0065] Particularly preferred substitutions are:
[0066] Lys for Arg and vice versa such that a positive charge may
be maintained;
[0067] Glu for Asp and vice versa such that a negative charge may
be maintained;
[0068] Ser for Thr such that a free --OH can be maintained; and
[0069] Gln for Asn such that a free NH.sub.2 can be maintained.
[0070] Amino acid substitutions may also be introduced to
substitute an amino acid with a particularly preferable property.
For example, a Cys may be introduced a potential site for disulfide
bridges with another Cys. A His may be introduced as a particularly
"catalytic" site (i.e., His can act as an acid or base and is the
most common amino acid in biochemical catalysis). Pro may be
introduced because of its particularly planar structure, which
induces turns in the protein's structure.
[0071] Two amino acid sequences are "substantially homologous" when
at least about 70% of the amino acid residues (preferably at least
about 80%, and most preferably at least about 90 or 95%) are
identical, or represent conservative substitutions.
[0072] A "heterologous" region of the DNA construct is an
identifiable segment of DNA within a larger DNA molecule that is
not found in association with the larger molecule in nature. Thus,
when the heterologous region encodes a mammalian gene, the gene
will usually be flanked by DNA that does not flank the mammalian
genomic DNA in the genome of the source organism. Another example
of a heterologous coding sequence is a construct where the coding
sequence itself is not found in nature (e.g., a cDNA where the
genomic coding sequence contains introns, or synthetic sequences
having codons different than the native gene). Allelic variations
or naturally-occurring mutational events do not give rise to a
heterologous region of DNA as defined herein.
[0073] An "antibody" is any immunoglobulin, including antibodies
and fragments thereof, that binds a specific epitope. The term
encompasses polyclonal, monoclonal, and chimeric antibodies, the
last mentioned described in further detail in U.S. Pat. Nos.
4,816,397 and 4,816,567.
[0074] An "antibody combining site" is that structural portion of
an antibody molecule comprised of heavy and light chain variable
and hypervariable regions that specifically binds antigen.
[0075] The phrase "antibody molecule" in its various grammatical
forms as used herein contemplates both an intact immunoglobulin
molecule and an immunologically active portion of an immunoglobulin
molecule.
[0076] Exemplary antibody molecules are intact immunoglobulin
molecules, substantially intact immunoglobulin molecules and those
portions of an immunoglobulin molecule that contains the paratope,
including those portions known in the art as Fab, Fab',
F(ab').sub.2 and F(v), which portions are preferred for use in the
therapeutic methods described herein.
[0077] The phrase "monoclonal antibody" in its various grammatical
forms refers to an antibody having only one species of antibody
combining site capable of immunoreacting with a particular antigen.
A monoclonal antibody thus typically displays a single binding
affinity for any antigen with which it immunoreacts. A monoclonal
antibody may therefore contain an antibody molecule having a
plurality of antibody combining sites, each immunospecific for a
different antigen; e.g., a bispecific (chimeric) monoclonal
antibody.
[0078] "Heart failure" refers to the incapacity of the heart to
assume a normal contractile function.
[0079] "Treat and treatment" refer to both therapeutic treatment
and prophylactic or preventative measures, wherein the object is to
prevent or slow down (lessen) an undesired physiological condition,
disorder or disease or obtain beneficial or desired clinical
results. For purposes of this invention, beneficial or desired
clinical results include, but are not limited to, alleviation of
symptoms; diminishment of extent of condition, disorder or disease;
stabilized (i.e. not worsening) state of condition, disorder or
disease; delay or slowing of condition, disorder, or disease
progression; amelioration of the condition, disorder or disease
state, remission (whether partial or total), whether detectable or
undetectable; or enhancement or improvement of condition, disorder
or disease. Treatment includes eliciting a cellular response that
is clinically significant, without excessive levels of side
effects. Treatment also includes prolonging survival as compared to
expected survival if not receiving treatment.
[0080] The phrase "pharmaceutically acceptable" refers to molecular
entities and compositions that are physiologically tolerable and do
not typically produce an allergic or similar untoward reaction,
such as gastric upset, dizziness and the like, when administered to
a human.
[0081] "Pharmaceutically acceptable salts" includes salts of
compounds derived from the combination of a compound and an organic
or inorganic acid. These compounds are useful in both free base and
salt form. In practice, the use of the salt form amounts to use of
the base form; both acid and base addition salts are within the
scope of the present invention.
[0082] "Pharmaceutically acceptable acid addition salt" refers to
salts retaining the biological effectiveness and properties of the
free bases and which are not biologically or otherwise undesirable,
formed with inorganic acids such as hydrochloric acid, hydrobromic
acid, sulfuric acid, nitric acid, phosphoric acid and the like, and
organic acids such as acetic acid, propionic acid, glycolic acid,
pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic
acid, fumaric acid, tartaric acid, citric acid, benzoic acid,
cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic
acid, p-toluenesulfonic acid, salicyclic acid and the like.
[0083] "Pharmaceutically acceptable base addition salts" include
those derived from inorganic bases such as sodium, potassium,
lithium, ammonium, calcium, magnesium, iron, zinc, copper,
manganese, aluminum salts and the like. Particularly preferred are
the ammonium, potassium, sodium, calcium and magnesium salts. Salts
derived from pharmaceutically acceptable organic nontoxic bases
include salts of primary, secondary, and tertiary amines,
substituted amines including naturally occurring substituted
amines, cyclic amines and basic ion exchange resins, such as
isopropylamine, trimethylamine, diethylamine, triethylamine,
tripropylamine, ethanolamine, 2-diethylaminoethanol, trimethamine,
dicyclohexylamine, lysine, arginine, histidine, caffeine, procaine,
hydrabamine, choline, betaine, ethylenediamine, glucosamine,
methylglucamine, theobromine, purines, piperizine, piperidine,
N-ethylpiperidine, polyamine resins and the like. Particularly
preferred organic nontoxic bases are isopropylamine, diethylamine,
ethanolamine, trimethamine, dicyclohexylamine, choline, and
caffeine.
[0084] "Parenteral" refers to introduction of the polypeptide by
intravenous, intraarterial, intraperitoneal, intramuscular,
intraventricular, intracranial, subcutaneous, subdermal,
transvaginal, oral, nasal or rectal routes.
[0085] "Mammal" refers to any animal classified as a mammal,
including humans, domestic and farm animals, and zoo, sports and
pet companion animals such as a household pet and other
domesticated animal such as, but not limited to, cattle, sheep,
ferrets, swine, horses, poultry, rabbits, goats, dogs, cats, and
the like. Preferred companion animals are dogs and cats.
Preferably, the mammal is human.
[0086] "Patient" refers to a mammal, preferably a human, in need of
treatment of a condition, disorder or disease.
[0087] "Inhibitor" includes but is not limited to, any suitable
molecule, compound, protein or fragment thereof, nucleic acid,
formulation or substance that can regulate Mst1 activity in such a
way that Mst1 is decreased or wherein the effects of Mst1 are
blocked or altered. The inhibitor includes an antagonist of Mst1,
particularly an Mst1 mutant or altered form that acts as a dominant
negative. An inhibitor of the Mst1 pathway includes any substance
that alters the effect of Mst1 at the level downstream or upstream
of Mst1. These include downstream proteins capable of being
modulated, including activated, by a signal from Mst1 or which are
more active on a signal from Mst1 or in the presence of
phosphorylated Mst1 or increased relative levels of cleaved Mst1.
Mst1 pathway further includes the upstream proteins, including
particulary a kinase(s), which are capable of phosphorylating amino
acid(s) on Mst1 or involved in the signal which results in
phosphorylated Mst1 or activated, cleaved Mst1. Exemplary
downstream proteins include but are not limited to caspase and
myelinbasic protein. The inhibitor can include, but is not limited
to the specifically identified Caspase 3, Calyculin A and
Chelerythrine. The inhibitor includes compounds which block Mst1
expression, including transcription or translation, such as
antisense nucleic acids, siRNAs and ribozymes.
[0088] As used herein, "pg" means picogram, "ng" means nanogram,
"ug" or ".mu.g" mean microgram, "mg" means milligram, "ul" or
".mu.l" mean microliter, "ml" means milliliter, "l" means
liter.
[0089] A DNA sequence is "operatively linked" to an expression
control sequence when the expression control sequence controls and
regulates the transcription and translation of that DNA sequence.
The term "operatively linked" includes having an appropriate start
signal (e.g., ATG) in front of the DNA sequence to be expressed and
maintaining the correct reading frame to permit expression of the
DNA sequence under the control of the expression control sequence
and production of the desired product encoded by the DNA sequence.
If a gene that one desires to insert into a recombinant DNA
molecule does not contain an appropriate start signal, such a start
signal can be inserted in front of the gene.
[0090] The term "standard hybridization conditions" refers to salt
and temperature conditions substantially equivalent to 5.times.SSC
and 65.degree. C. for both hybridization and wash. However, one
skilled in the art will appreciate that such "standard
hybridization conditions" are dependent on particular conditions
including the concentration of sodium and magnesium in the buffer,
nucleotide sequence length and concentration, percent mismatch,
percent formamide, and the like. Also important in the
determination of "standard hybridization conditions" is whether the
two sequences hybridizing are RNA-RNA, DNA-DNA or RNA-DNA. Such
standard hybridization conditions are easily determined by one
skilled in the art according to well known formulae, wherein
hybridization is typically 10-20.sup.NC below the predicted or
determined T.sub.m with washes of higher stringency, if
desired.
Screening Methods and Assays
[0091] Once a compound that binds to Mst1 or otherwise modulates
the Mst1 pathway is selected, it can be tested for its ability to
modulate cardiac myocyte apoptosis or function. The effect of
compounds on cardiac myocyte apoptosis can also be tested in vivo.
Cardiac function and output can be measured in vivo in animals by
methods and assays well known in the art, including as described
herein. In one such example of this assay, including as described
herein, a myocardial infarction is generated in animal by ligation
of the left coronary artery and the animals are then observed for
cardiac myopathy and cardiac function.
[0092] The function of cardiac myocytes and status of the Mst1
pathway may be determined by assessing the activation of
intracellular proteins indicative of apoptosis and/or Mst1
activation, particularly including, but not limited to, proteins or
kinases such as caspase, Mst1 cleavage status, MAPK, JNK, etc.
which may be substrates for Mst1 or activated or more active in the
presence of phosphorylated or cleaved Mst1, or active on initiation
of apoptosis. In addition, the activation of Mst1 or
phosphorylation of Mst1 or its substrate, including MBP, may be
assessed. Thus, following the incubation of cardiac myocytes or
other cells expressing Mst1 with a test compound, the cells are
lysed and their intracellular contents subjected to the appropriate
tests, such as Western blots, kinase assays, and electrophoretic
mobility gel shift assays (EMSAs).
[0093] In one embodiment, the modulation comprises phosphorylation
of intracellular proteins in the Mst1 pathway, and more preferably
of kinases, particularly including Mst1. The methods of the present
invention may utilize any of the appropriate assays available in
the art for determining whether a kinase has been phosphorylated.
Preferably, the assays used are Western blots or kinase assays.
[0094] In an embodiment, methods for screening cardiotherapeutic
compounds based on their ability to activate phosphatase(s)
(partially or completely) are also provided herein. The compounds
to be screened may include compounds that bind to Mst1 or
dephopsphorylate Mst1, and methods for selecting such compounds are
described above. The phosphatases inhibit the kinases specific for
cardiac myocyte apoptosis and/or function, including Mst1 and
proteins (kinases) in the Mst1 pathway which may be substrates for
Mst1 or activated or more active in the presence of phosphorylated
Mst1, e.g. caspase. Preferably, the phosphatases are Mst1 specific
or Mst1 pathway specific. While not being bound to a particular
theory, this method is feasible for this purpose due to the fact
that in some instances a kinase activity is tightly regulated by
its corresponding phosphatase. In case of ERK1/2, the phosphatases
are known as the mitogen activated protein kinases
phosphatase-1,2,3 (MKP-1,2,3). These phosphatases belong to a
family of dual specificity phosphatases, which are responsible for
the removal of phosphate groups from the threonine and tyrosine
residues on their corresponding kinases (Camps et al., FASEB J.,
14, pp. 6-16, 1999). The prompt removal of phosphate groups by
phosphatases ensures that kinase activation is short-lived and that
the level of phosphorylation is low in a resting cell. However, in
order for the phosphatase to be active and remove phosphate groups,
it also needs to be phosphorylated. Therefore, activation of
phosphatase activity results in inactivation of kinase activity.
The ability of the test compounds to activate phosphatase(s) can be
determined by performing Western blots or kinase assays. See above.
For additional details on assessing phosphatase activity, see Muda
et al., J Biol. Chem., 273:9323-9329, 1998, and Camps et al.,
Science 280:1262-1265, 1998. If the compound is determined to
possess enhanced phosphatase activity, it can further be tested in
one of the cardiac myocyte apoptosis or in vitro or in vivo assays
to determine its effect on cardiac function and/or
cardiomyopathy.
[0095] In a further embodiment of this invention, commercial test
kits suitable for use by a medical specialist may be prepared to
determine the presence or absence of or the amount of Mst1 or Mst1
activity in cells. Accordingly, one class of such kits will contain
at least the labeled Mst1 or its binding partner, for instance an
antibody specific thereto, and directions, of course, depending
upon the method selected, e.g., competitive, sandwich, and the
like, all and any of which are methods well known to the skilled
artisan. The kits may also contain peripheral reagents such as
buffers, stabilizers, etc.
[0096] Accordingly, a test kit may be prepared for the
demonstration of the presence or capability of cells for Mst1
activity, comprising:
[0097] (a) a predetermined amount of at least one labeled
immunochemically reactive component obtained by the direct or
indirect attachment of Mst1 or a specific binding partner thereto,
to a detectable label;
[0098] (b) other reagents; and
[0099] (c) directions for use of said kit.
[0100] More specifically, the diagnostic test kit may comprise:
[0101] (a) a known amount of Mst1 as described above (or a binding
partner) generally bound to a solid phase to form an immunosorbent,
or in the alternative, bound to a suitable tag, or plural such end
products, etc. (or their binding partners) one of each;
[0102] (b) if necessary, other reagents; and
[0103] (c) directions for use of said test kit.
[0104] In a further variation, the test kit may be prepared and
used for the purposes stated above, which operates according to a
predetermined protocol (e.g. competitive, sandwich, double
antibody, etc.), and comprises:
[0105] (a) a labeled component which has been obtained by coupling
Mst1 to a detectable label;
[0106] (b) one or more additional immunochemical reagents of which
at least one reagent is a ligand or an immobilized ligand, which
ligand is selected from the group consisting of: [0107] (i) a
ligand capable of binding with the labeled component (a); [0108]
(ii) a ligand capable of binding with a binding partner of the
labeled component (a); [0109] (iii) a ligand capable of binding
with at least one of the component(s) to be determined; and [0110]
(iv) a ligand capable of binding with at least one of the binding
partners of at least one of the component(s) to be determined;
and
[0111] (c) directions for the performance of a protocol for the
detection and/or determination of one or more components of an
immunochemical reaction between Mst1 and a specific binding partner
thereto.
Compounds and Agents
[0112] Examples of agents, candidate compounds or test compounds
include, but are not limited to, nucleic acids (e.g., DNA and RNA),
carbohydrates, lipids, proteins, peptides, peptidomimetics, small
molecules and other drugs. In one preferred aspect, agents can be
obtained using any of the numerous suitable approaches in
combinatorial library methods known in the art, including:
biological libraries; spatially addressable parallel solid phase or
solution phase libraries; synthetic library methods requiring
deconvolution; the "one-bead one-compound" library method; and
synthetic library methods using affinity chromatography selection.
The biological library approach is limited to peptide libraries,
while the other four approaches are applicable to peptide,
non-peptide oligomer or small molecule libraries of compounds (Lam,
1997, Anticancer Drug Des. 12:145; U.S. Pat. No. 5,738,996; and
U.S. Pat. No. 5,807,683).
[0113] Phage display libraries may be used to screen potential Mst1
modulators. Their usefulness lies in the ability to screen, for
example, a library displaying a billion different compounds with
only a modest investment of time, money, and resources. For use of
phage display libraries in a screening process, see, for instance,
Kay et al., Methods, 240-246, 2001. An exemplary scheme for using
phage display libraries to identify compounds that bind or interact
with Mst1 may be described as follows: initially, an aliquot of the
library is introduced into microtiter plate wells that have
previously been coated with target protein, e.g. Mst1. After
incubation (e.g. 2 hrs), the nonbinding phage are washed away, and
the bound phage are recovered by denaturing or destroying the
target with exposure to harsh conditions such as, for instance pH
2, but leaving the phage intact. After transferring the phage to
another tube, the conditions are neutralized, followed by infection
of bacteria with the phage and production of more phage particles.
The amplified phage are then rescreened to complete one cycle of
affinity selection. After three or more rounds of screening, the
phage are plated out such that there are individual plaques that
can be further analyzed. For example, the conformation of binding
activity of affinity-purified phage for Mst1 may be obtained by
performing ELISAs. One skilled in the art can easily perform these
experiments. In one aspect, an Mst1 molecule used for any of the
assays may be selected from a recombinant Mst1 protein, an Mst1
fusion protein, an analog, derivative, or mimic thereof. In a
preferred aspect, Mst1 is a recombinant Mst1 protein.
[0114] Examples of methods for the synthesis of molecular libraries
can be found in the art, for example in: DeWitt et al., 1993, Proc.
Natl. Acad. Sci. USA 90:6909; Erb et al., 1994, Proc. Natl. Acad.
Sci. USA 91:11422; Zuckermann et al., 1994, J. Med. Chem. 37:2678;
Cho et al., 1993, Science 261:1303; Carrell et al., 1994, Angew.
Chem. Int. Ed. Engl. 33:2059; Carell et al., 1994, Angew. Chem.
Int. Ed. Engl. 33:2061; and Gallop et al., 1994, J. Med. Chem.
37:1233.
[0115] Libraries of compounds may be presented, e.g., presented in
solution (e.g., Houghten, 1992, Bio/Techniques 13:412-421), or on
beads (Lam, 1991, Nature 354:82-84), chips (Fodor, 1993, Nature
364:555-556), bacteria (U.S. Pat. No. 5,223,409), spores (U.S. Pat.
Nos. 5,571,698; 5,403,484; and 5,223,409), plasmids (Cull et al.,
1992, Proc. Natl. Acad. Sci. USA 89:1865-1869) or phage (Scott and
Smith, 1990, Science 249:386-390; Devlin, 1990, Science
249:404-406; Cwirla et al., 1990, Proc. Natl. Acad. Sci. USA
87:6378-6382; and Felici, 1991, J. Mol. Biol. 222:301-310).
[0116] Antibodies, including polyclonal and monoclonal antibodies,
particularly anti-Mst1 antibodies and neutralizing antibodies may
be useful as compounds to modulate cardiac myocyte apoptosis and/or
function. Also, antibodies including both polyclonal and monoclonal
antibodies, and drugs that modulate the activity of Mst1 and/or
their subunits may possess certain diagnostic applications and may
for example, be utilized for the purpose of detecting and/or
measuring conditions such as cardiac disease, cardiomyopathy, or
cardiac function. Mst1 or its subunits may be used to produce both
polyclonal and monoclonal antibodies to themselves in a variety of
cellular media, by known techniques such as the hybridoma technique
utilizing, for example, fused mouse spleen lymphocytes and myeloma
cells. Likewise, small molecules that mimic or antagonize the
activity(ies) of Mst1 may be discovered or synthesized, and may be
used in diagnostic and/or therapeutic protocols.
[0117] The general methodology for making monoclonal antibodies by
hybridomas is well known. Immortal, antibody-producing cell lines
can also be created by techniques other than fusion, such as direct
transformation of B lymphocytes with oncogenic DNA, or transfection
with Epstein-Barr virus. See, e.g., M. Schreier et al., "Hybridoma
Techniques" (1980); Hammerling et al., "Monoclonal Antibodies And
T-cell Hybridomas" (1981); Kennett et al., "Monoclonal Antibodies"
(1980); see also U.S. Pat. Nos. 4,341,761; 4,399,121; 4,427,783;
4,444,887; 4,451,570; 4,466,917; 4,472,500; 4,491,632;
4,493,890.
[0118] Panels of monoclonal antibodies produced against Mst1
peptides can be screened for various properties; i.e., isotype,
epitope, affinity, etc. Of particular interest are monoclonal
antibodies that neutralize the activity of Mst1. Such monoclonals
can be readily identified in Mst1 activity assays, for instance in
kinase assays using MBP as substrate.
[0119] Once an Mst1 modulating compound has been optimally
designed, for example as described above, substitutions may then be
made in some of its atoms or chemical groups in order to improve or
modify its binding properties, or its pharmaceutical properties
such as stability or toxicity. Generally, initial substitutions are
conservative, i.e., the replacement group will have approximately
the same size, shape, hydrophobicity and charge as the original
group. One of skill in the art will understand that substitutions
known in the art to alter conformation should be avoided. Such
altered chemical compounds may then be analyzed for efficiency of
modulating Mst1, including in assays as described herein.
[0120] This invention also encompasses prodrug derivatives of the
compounds contained herein. The term "prodrug" refers to a
pharmacologically inactive derivative of a parent drug molecule
that requires biotransformation, either spontaneous or enzymatic,
within the organism to release the active drug. Prodrugs are
variations or derivatives of the compounds of this invention which
have groups cleavable under metabolic conditions. Prodrugs become
the compounds of the invention which are pharmaceutically active in
vivo, when they undergo solvolysis under physiological conditions
or undergo enzymatic degradation. Prodrug compounds of this
invention may be called single, double, triple etc., depending on
the number of biotransformation steps required to release the
active drug within the organism, and indicating the number of
functionalities present in a precursor-type form. Prodrug forms
often offer advantages of solubility, tissue compatibility, or
delayed release in the mammalian organism (see, Bundgard, Design of
Prodrugs, pp. 7-9, 21-24, Elsevier, Amsterdam 1985 and Silverman,
The Organic Chemistry of Drug Design and Drug Action, pp. 352-401,
Academic Press, San Diego, Calif., 1992). Prodrugs commonly known
in the art include acid derivatives well known to practitioners of
the art, such as, for example, esters prepared by reaction of the
parent acids with a suitable alcohol, or amides prepared by
reaction of the parent acid compound with an amine, or basic groups
reacted to form an acylated base derivative. Moreover, the prodrug
derivatives of this invention may be combined with other features
herein taught to enhance bioavailability. The preparation of
pharmaceutically acceptable isomers, solvates or hydrates would be
apparent to one of ordinary skill in the art.
Methods and Therapeutic and Pharmaceutical Compositions
[0121] The Mst1 modulators of the present invention, particularly.
Mst1 inhibitors, may be prepared in pharmaceutical compositions,
with a suitable carrier and at a strength effective for
administration by various means to a patient experiencing cardiac
disease, including cardiomyopathy or compromised cardiac function,
for the treatment or amelioration thereof. A variety of
administrative techniques may be utilized, among them parenteral
techniques such as subcutaneous, intravenous and intraperitoneal
injections, catheterizations and the like. Average quantities of
the modulators or their subunits may vary and in particular should
be based upon the recommendations and prescription of a qualified
physician or veterinarian.
[0122] A pharmaceutical composition useful in the present invention
comprises an Mst1 inhibitor (such as described above) and a
pharmaceutically acceptable carrier, excipient, diluent and/or
salt. Pharmaceutically acceptable carrier, diluent, excipient
and/or salt means that the carrier, diluent, excipient and/or salt
must be compatible with the other ingredients of the formulation,
does not adversely affect the therapeutic benefit of the Mst1
inhibitor, and is not deleterious to the recipient thereof.
[0123] In a preferred embodiment of the invention, a method of
treating or ameliorating cardiac disease is provided by
administering compositions comprising compounds identified by the
screening methods provided herein. The Mst1 modulating compositions
of the present invention may be utilized by providing an effective
amount of such compositions to a subject in need thereof.
[0124] The invention provides a method for treating cardiac disease
in a mammal comprising administering to said mammal an effective
amount of an Mst1 inhibitor. In a particular aspect, the invention
further provides a method for treating a cardiac disease or
dysfunction selected from the group of congestive heart failure,
cardiomyopathy, including ischemic and nonischemic cardiomyopathy,
coronary artery disease, arrhythmias, fibrosis of the heart, valve
defects, and atherosclerosis in a mammal comprising administering
to said mammal an effective amount of an Mst1 inhibitor. In a still
further aspect a method is provided for reducing the risk of
cardiomyopathy or dysfunction in a mammal after said mammal has
suffered a myocardial infarct or other coronary event wherein blood
flow to the heart is compromised or significantly reduced
comprising administering to said mammal an effective amount of an
Mst1 inhibitor or Mst1 pathway inhibitor. In an additional aspect,
the invention provides a method of cardioprotection, wherein an
inhibitor of Mst1 is administered in conjunction with or following
therapy with a compound or drug which is cardiotoxic or has
potential to be cardiotoxic. In this method, an Mst1 modulator
blocks or otherwise reduces the cardiotoxic effects of a drug or
compound. In a particular embodiment, the drug or compound is a
chemotherapeutic agent, particularly an anti-cancer agent,
including but not limited to doxorubicin. In a further aspect,
administration of the Mst1 modulator enables chemotherapeutic,
particularly anti-cancer or anti-tumor compounds, treatment without
significant cardiotoxic effects or permits prolonged chemotherapy
or administration of higher concentrations or amounts of a
potentially cardiotoxic drug.
[0125] In general, for use in treatment, the compounds of the
invention may be used alone or in combination with other
compositions for the treatment of heart disease, including but not
limited to congestive heart failure, cardiomyopathy, including
ischemic and nonischemic cardiomyopathy, coronary artery disease,
arrhythmias, fibrosis of the heart, valve defects, and
atherosclerosis. In particular, an effective amount of an Mst1
inhibitor may be used in combination with one or more compound for
treatment of cardiac disease or of atherosclerosis, including but
not limited to a beta-blocker, nitrate, calcium channel
antagonists, angiotensin-converting enzyme (ACE) inhibitors, an
anti-platelet drug, diuretics, digoxin and antilipemic agents,
agents which alter cholesterol or lipid metabolism. Further
examples of such or treatmantilipemic agents include, but are not
limited to the statins, such as Lovastatin (Mevacor.RTM.),
Atorvastatin (Lipitor.RTM.), Simvastatin (Zocor.RTM.), Cerivastatin
(Baycol.RTM.), Pravastatin (Pravacol.RTM.), Fluvastatin
(Lescol.RTM.) and Rosuvastatin; as well as other classes of
compounds including cholesterol ester transfer protein inhibitors;
cholesterol adsorption inhibitors (e.g., Ezetimide.RTM.); fibrates
(e.g., Gemfibrozil.RTM.); nicotinic acid (e.g., niacin and analogs,
Niaspan.RTM.); bile acid reuptake inhibitors; and modulators of
nuclear hormone receptors such as PPARa, PPARb, PPARg, LXRa, LXRb,
FXR, RORa and SHP.
[0126] Administration of the compounds or pharmaceutical
compositions thereof for practicing the present invention can be by
any method that delivers the compounds systemically. These methods
include oral routes, parenteral routes, intraduodenal routes,
etc.
[0127] For topical applications, the compound or pharmaceutical
composition thereof can be formulated in a suitable ointment
containing the active component suspended or dissolved in one or
more carriers. Carriers for topical administration of the compounds
of this invention include, but are not limited to, mineral oil,
liquid petrolatum, white petrolatum, propylene glycol,
polyoxyethylene, polyoxypropylene compound, emulsifying wax, sugars
such as lactose and water. Alternatively, the pharmaceutical
compositions can be formulated in a suitable lotion or cream
containing the active components suspended or dissolved in one or
more pharmaceutically acceptable carriers. Suitable carriers
include, but are not limited to, mineral oil, sorbitan
monostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol,
2-octyldodecanol, benzyl alcohol and water.
[0128] Depending on the particular condition, disorder or disease
to be treated, additional therapeutic agents can be administered
together with the Mst1 inhibitor. Those additional agents can be
administered sequentially in any order, as part of a multiple
dosage regimen, from the Mst1 inhibitor intermittent
administration). Alternatively, those agents can be part of a
single dosage form, mixed together with the Mst1 inhibitor in a
single composition (simultaneous or concurrent administration).
[0129] For oral administration, a pharmaceutical composition useful
in the invention can take the form of solutions, suspensions,
tablets, pills, capsules, powders, granules, semisolids, sustained
release formulations, elixirs, aerosols, and the like. Tablets
containing various excipients such as sodium citrate, calcium
carbonate and calcium phosphate are employed along with various
disintegrants such as starch, preferably potato or tapioca starch,
and certain complex silicates, together with binding agents such as
polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally,
lubricating agents such as magnesium stearate, sodium lauryl
sulfate and talc are often very useful for tabletting purposes.
Solid compositions of a similar type are also employed as fillers
in soft and hard-filled gelatin capsules; preferred materials in
this connection also include lactose or milk sugar as well as high
molecular weight polyethylene glycols. When aqueous suspensions
and/or elixirs are desired for oral administration, the compounds
of this invention can be combined with various sweetening agents,
flavoring agents, coloring agents, emulsifying agents and/or
suspending agents, as well as such diluents as water, ethanol,
propylene glycol, glycerin and various like combinations
thereof.
[0130] The choice of formulation depends on various factors such as
the mode of drug administration (e.g., for oral administration,
formulations in the form of tablets, pills or capsules are
preferred) and the bioavailability of the drug substance. Recently,
pharmaceutical formulations have been developed especially for
drugs that show poor bioavailability based upon the principle that
bioavailability can be increased by increasing the surface area
i.e., decreasing particle size. For example, U.S. Pat. No.
4,107,288 describes a pharmaceutical formulation having particles
in the size range from 10 to 1,000 nm in which the active material
is supported on a crosslinked matrix of macromolecules: U.S. Pat.
No. 5,145,684 describes the production of a pharmaceutical
formulation in which the drug substance is pulverized to
nanoparticles (average particle size of 400 nm) in the presence of
a surface modifier and then dispersed in a liquid medium to give a
pharmaceutical formulation that exhibits remarkably high
bioavailability.
[0131] The term "parenteral" as used herein refers to modes of
administration, which include intravenous, intramuscular,
intraperitoneal, intrasternal, subcutaneous, intramedullary and
intraarticular injection and infusion. A pharmaceutical composition
for parenteral injection can comprise pharmaceutically acceptable
sterile aqueous or nonaqueous solutions, dispersions, suspensions
or emulsions as well as sterile powders for reconstitution into
sterile injectable solutions or dispersions just prior to use.
Aqueous solutions are especially suitable for intravenous,
intramuscular, subcutaneous and intraperitoneal injection purposes.
In this connection, the sterile aqueous media employed are all
readily obtainable by standard techniques well-known to those
skilled in the art. Examples of suitable aqueous and nonaqueous
carriers, diluents, solvents or vehicles include water, ethanol,
polyols (such as glycerol, propylene glycol, polyethylene glycol,
and the like), carboxymethylcellulose and suitable mixtures
thereof, vegetable oils (such as olive oil), and injectable organic
esters such as ethyl oleate. Proper fluidity can be maintained, for
example, by the use of coating materials such as lecithin, by the
maintenance of the required particle size in the case of
dispersions, and by the use of surfactants.
[0132] The pharmaceutical compositions useful in the present
invention can also contain adjuvants such as, but not limited to,
preservatives, wetting agents, emulsifying agents, and dispersing
agents. Prevention of the action of microorganisms can be ensured
by the inclusion of various antibacterial and antifungal agents,
such as for example, paraben, chlorobutanol, phenol sorbic acid,
and the like. It can also be desirable to include isotonic agents
such as sugars, sodium chloride, and the like. Prolonged absorption
of the injectable pharmaceutical form can be brought about by the
inclusion of agents that delay absorption such as aluminum
monostearate and gelatin.
[0133] In some cases, in order to prolong the effect of the drugs,
it is desirable to slow the absorption from subcutaneous or
intramuscular injection. This can be accomplished by the use of a
liquid suspension of crystalline or amorphous material with poor
water solubility. The rate of absorption of the drug then depends
upon its rate of dissolution which, in turn, can depend upon
crystal size and crystalline form. Alternatively, delayed
absorption of a parenterally administered drug form is accomplished
by dissolving or suspending the drug in an oil vehicle.
[0134] Injectable depot forms are made by forming microencapsule
matrices of the drug in biodegradable polymers such as polylactide,
polyglycolide, and polylactide-polyglycolide. Depending upon the
ratio of drug to polymer and the nature of the particular polymer
employed, the rate of drug release can be controlled. Examples of
other biodegradable polymers include poly(orthoesters) and
poly(anhydrides). Depot injectable formulations are also prepared
by entrapping the drug in liposomes or microemulsions that are
compatible with body tissues.
[0135] The injectable formulations can be sterilized, for example,
by filtration through a bacterial-retaining filter, or by
incorporating sterilizing agents in the form of sterile solid
compositions which can be dissolved or dispersed in sterile water
or other sterile injectable medium just prior to use.
[0136] Administration by slow infusion is particularly useful when
intrathecal or epidural routes are employed. A number of
implantable or body mountable pumps useful in delivering compound
at a regulated rate are known in the art. See, e.g., U.S. Pat. No.
4,619,652.
[0137] Suspensions, in addition to the active compounds, can
contain suspending agents as, for example, ethoxylated isostearyl
alcohols, polyoxyethylene sorbitol and sorbitan esters,
microcrystalline cellulose, aluminum metahydroxide, bentonite,
agar-agar, and tragacanth, and mixtures thereof.
[0138] For purposes of transdermal (e.g., topical) administration,
dilute sterile, aqueous or partially aqueous solutions (usually in
about 0.1% to 5% concentration), otherwise similar to the above
parenteral solutions, are prepared.
[0139] The pharmaceutical compositions useful in the invention can
also be administered by nasal aerosol or inhalation. Such
compositions are prepared according to techniques well-known in the
art of pharmaceutical formulation and can be prepared as solutions
in saline, employing benzyl alcohol or other suitable
preservatives, absorption promoters to enhance bioavailability,
fluorocarbons, and/or other conventional solubilizing or dispersing
agents.
[0140] In nonpressurized powder compositions, the active
ingredients in finely divided form can be used in admixture with a
larger-sized pharmaceutically acceptable inert carrier comprising
particles having a size, for example, of up to 100 .mu.m in
diameter. Suitable inert carriers include sugars such as lactose.
Desirably, at least 95% by weight of the particles of the active
ingredient have an effective particle size in the range of 0.01 to
10 .mu.m.
[0141] Alternatively, the composition can be pressurized and
contain a compressed gas, such as, e.g., nitrogen, carbon dioxide
or a liquefied gas propellant. The liquefied propellant medium and
indeed the total composition are preferably such that the active
ingredients do not dissolve therein to any substantial extent. The
pressurized composition can also contain a surface active agent.
The surface active agent can be a liquid or solid non-ionic surface
active agent or can be a solid anionic surface active agent. It is
preferred to use the solid anionic surface active agent in the form
of a sodium salt.
[0142] Compositions for rectal or vaginal administration are
preferably suppositories which can be prepared by mixing the
compounds of the invention with suitable non-irritating excipients
or carriers such as cocoa butter, polyethylene glycol or a
suppository wax which are solid at room temperature but liquid at
body temperature and therefore melt in the rectum or vaginal cavity
and release the drugs.
[0143] The compositions useful in the present invention can also be
administered in the form of liposomes. As is known in the art,
liposomes are generally derived from phospholipids or other lipid
substances. Liposomes are formed by mono- or multi-lamellar
hydrated liquid crystals that are dispersed in an aqueous medium.
Any non-toxic, physiologically acceptable and metabolizable lipid
capable of forming liposomes can be used. The present compositions
in liposome form can contain, in addition to the compounds of the
invention, stabilizers, preservatives, excipients, and the like.
The preferred lipids are the phospholipids and the phosphatidyl
cholines (lecithins), both natural and synthetic. Methods to form
liposomes are known in the art (see e.g., Prescott, E., Meth. Cell
Biol. 14:33 (1976)).
[0144] Other pharmaceutically acceptable carrier includes, but is
not limited to, a non-toxic solid, semisolid or liquid filler,
diluent, encapsulating material or formulation auxiliary of any
type, including but not limited to ion exchangers, alumina,
aluminum stearate, lecithin, serum proteins, such as human serum
albumin, buffer substances such as phosphates, glycine, sorbic
acid, potassium sorbate, partial glyceride mixtures of saturated
vegetable fatty acids, water, salts or electrolytes, such as
protamine sulfate, disodium hydrogen phosphate, potassium hydrogen
phosphate, sodium chloride, zinc salts, colloidal silica, magnesium
trisilicate, polyvinyl pyrrolidone, cellulose-based substances,
polyethylene glycol, sodium carboxymethylcellulose, polyacrylates,
waxes, polyethylene-polyoxypropylene-block polymers, polyethylene
glycol and wool fat.
[0145] Solid pharmaceutical excipients include, but are not limited
to, starch, cellulose, talc, glucose, lactose, sucrose, gelatin,
malt, rice, flour, chalk, silica gel, magnesium stearate, sodium
stearate, glycerol monostearate, sodium chloride, dried skim milk
and the like. Liquid and semisolid excipients can be selected from
glycerol, propylene glycol, water, ethanol and various oils,
including those of petroleum, animal, vegetable or synthetic
origin, e.g., peanut oil, soybean oil, mineral oil, sesame oil,
etc. Preferred liquid carriers, particularly for injectable
solutions, include water, saline, aqueous dextrose, and
glycols.
[0146] Methods of preparing various pharmaceutical compositions
with a certain amount of active ingredient are known, or will be
apparent in light of this disclosure, to those skilled in this art.
Other suitable pharmaceutical excipients and their formulations are
described in Remington's Pharmaceutical Sciences, edited by E. W.
Martin, Mack Publishing Company, 19th ed. (1995).
[0147] Pharmaceutical compositions useful in the present invention
can contain 0.1%-95% of the compound(s) of this invention,
preferably 1%-70%. In any event, the composition or formulation to
be administered will contain a quantity of a compound(s) according
to this invention in an amount effective to treat the condition,
disorder or disease of the subject being treated.
[0148] One of ordinary skill in the art will appreciate that
pharmaceutically effective amounts of the Mst1 inhibitor can be
determined empirically and can be employed in pure form or, where
such forms exist, in pharmaceutically acceptable salt, ester or
prodrug form. The agents can be administered to a patient as
pharmaceutical compositions in combination with one or more
pharmaceutically acceptable excipients. It will be understood that,
when administered to, for example, a human patient, the total daily
usage of the agents or composition of the present invention will be
decided within the scope of sound medical judgement by the
attending physician. The specific therapeutically effective dose
level for any particular patient will depend upon a variety of
factors: the type and degree of the cellular response to be
achieved; activity of the specific agent or composition employed;
the specific agents or composition employed; the age, body weight,
general health, sex and diet of the patient; the time of
administration, route of administration, and rate of excretion of
the agent; the duration of the treatment; drugs used in combination
or coincidental with the specific agent; and like factors well
known in the medical arts. For example, it is well within the skill
of the art to start doses of the agents at levels lower than those
required to achieve the desired therapeutic effect and to gradually
increase the dosages until the desired effect is achieved.
[0149] For example, satisfactory results are obtained by oral
administration of the compounds at dosages on the order of from
0.05 to 500 mg/kg/day, preferably 0.1 to 100 mg/kg/day, more
preferably 1 to 50 mg/kg/day, administered once or, in divided
doses, 2 to 4 times per day. On administration parenterally, for
example, by i.v. bolus, drip or infusion, dosages on the order of
from 0.01 to 1000 mg/kg/day, preferably 0.05 to 500 mg/kg/day, and
more preferably 0.1 to 100 mg/kg/day, can be used. Suitable daily
dosages for patients are thus on the order of from 2.5 to 500 mg
p.o., preferably 5 to 250 mg p.o., more preferably 5 to 100 mg
p.o., or on the order of from 0.5 to 250 mg i.v., preferably 2.5 to
125 mg i.v. and more preferably 2.5 to 50 mg i.v.
[0150] Dosaging can also be arranged in a patient specific manner
to provide a predetermined concentration of the agents in the
blood, as determined by techniques accepted and routine in the art
(HPLC is preferred). Thus patient dosaging can be adjusted to
achieve regular on-going blood levels, as measured by HPLC, on the
order of from 50 to 5000 ng/ml, preferably 100 to 2500 ng/ml.
[0151] The preparation of therapeutic compositions which contain
polypeptides, analogs or active fragments as active ingredients is
well understood in the art. Typically, such compositions are
prepared as injectables, either as liquid solutions or suspensions,
however, solid forms suitable for solution in, or suspension in,
liquid prior to injection can also be prepared. The preparation can
also be emulsified. The active therapeutic ingredient is often
mixed with excipients which are pharmaceutically acceptable and
compatible with the active ingredient. Suitable excipients are, for
example, water, saline, dextrose, glycerol, ethanol, or the like
and combinations thereof. In addition, if desired, the composition
can contain minor amounts of auxiliary substances such as wetting
or emulsifying agents, pH buffering agents which enhance the
effectiveness of the active ingredient.
[0152] A polypeptide, analog or active fragment can be formulated
into the therapeutic composition as neutralized pharmaceutically
acceptable salt forms. Pharmaceutically acceptable salts include
the acid addition salts (formed with the free amino groups of the
polypeptide or antibody molecule) and which are formed with
inorganic acids such as, for example, hydrochloric or phosphoric
acids, or such organic acids as acetic, oxalic, tartaric, mandelic,
and the like. Salts formed from the free carboxyl groups can also
be derived from inorganic bases such as, for example, sodium,
potassium, ammonium, calcium, or ferric hydroxides, and such
organic bases as isopropylamine, trimethylamine, 2-ethylamino
ethanol, histidine, procaine, and the like.
[0153] The therapeutic polypeptide-, analog-, -modulator or active
fragment-containing compositions are conventionally administered
intravenously, as by injection of a unit dose, for example. The
term "unit dose" when used in reference to a therapeutic
composition of the present invention refers to physically discrete
units suitable as unitary dosage for humans, each unit containing a
predetermined quantity of active material calculated to produce the
desired therapeutic effect in association with the required
diluent; i.e., carrier, or vehicle.
[0154] The compositions are administered in a manner compatible
with the dosage formulation, and in a therapeutically effective
amount. The quantity to be administered depends on the subject to
be treated, capacity of the subject's immune system to utilize the
active ingredient, and degree of inhibition or neutralization of
.about.binding capacity desired. Precise amounts of active
ingredient required to be administered depend on the judgment of
the practitioner and are peculiar to each individual. However,
suitable dosages may range from about 0.1 to 20, preferably about
0.5 to about 10, and more preferably one to several, milligrams of
active ingredient per kilogram body weight of individual per day
and depend on the route of administration. Suitable regimes for
initial administration and booster shots are also variable, but are
typified by an initial administration followed by repeated doses at
one or more hour intervals by a subsequent injection or other
administration. Alternatively, continuous intravenous infusion
sufficient to maintain concentrations of ten nanomolar to ten
micromolar in the blood are contemplated.
[0155] The therapeutic compositions may further include an
effective amount of the Mst1 antagonist or analog or modulator
thereof, and one or more of the following active ingredients,
including but not limited to: an antibiotic, a steroid, an
anticoagulant, a statin or other cholesterol lowering drug, an
anti-hypertensive drug, an immune modulatory drug.
[0156] Another feature of this invention is the expression of the
DNA sequences disclosed herein, including Mst1, particularly
altered, including dominant negative forms of Mst1. As is well
known in the art, DNA sequences may be expressed by operatively
linking them to an expression control sequence in an appropriate
expression vector and employing that expression vector to transform
an appropriate unicellular host.
[0157] Such operative linking of a DNA sequence of this invention
to an expression control sequence, of course, includes, if not
already part of the DNA sequence, the provision of an initiation
codon, ATG, in the correct reading frame upstream of the DNA
sequence.
[0158] A wide variety of host/expression vector combinations may be
employed in expressing the DNA sequences of this invention. Useful
expression vectors, for example, may consist of segments of
chromosomal, non-chromosomal and synthetic DNA sequences. Suitable
vectors include derivatives of SV40 and known bacterial plasmids,
e.g., E. coli plasmids col El, pCR1, pBR322, pMB9 and their
derivatives, plasmids such as RP4; phage DNAS, e.g., the numerous
derivatives of phage .quadrature., e.g., NM989, and other phage
DNA, e.g., M13 and filamentous single stranded phage DNA; yeast
plasmids such as the 2.mu. plasmid or derivatives thereof; vectors
useful in eukaryotic cells, such as vectors useful in insect or
mammalian cells; vectors derived from combinations of plasmids and
phage DNAs, such as plasmids that have been modified to employ
phage DNA or other expression control sequences; and the like.
[0159] Any of a wide variety of expression control
sequences--sequences that control the expression of a DNA sequence
operatively linked to it--may be used in these vectors to express
the DNA sequences of this invention. Such useful expression control
sequences include, for example, the early or late promoters of
SV40, CMV, vaccinia, polyoma or adenovirus, the lac system, the trp
system, the TAC system, the TRC system, the LTR system, the major
operator and promoter regions of phage .quadrature., the control
regions of fd coat protein, the promoter for 3-phosphoglycerate
kinase or other glycolytic enzymes, the promoters of acid
phosphatase (e.g., Pho5), the promoters of the yeast-mating
factors, and other sequences known to control the expression of
genes of prokaryotic or eukaryotic cells or their viruses, and
various combinations thereof.
[0160] A wide variety of unicellular host cells are also useful in
expressing the DNA sequences of this invention. These hosts may
include well known eukaryotic and prokaryotic hosts, such as
strains of E. coli, Pseudomonas, Bacillus, Streptomyces, fungi such
as yeasts, and animal cells, such as CHO, R1.1, B--W and L-M cells,
African Green Monkey kidney cells (e.g., COS 1, COS 7, BSC1, BSC40,
and BMT10), insect cells (e.g., Sf9), and human cells and plant
cells in tissue culture.
[0161] It will be understood that not all vectors, expression
control sequences and hosts will function equally well to express
the DNA-sequences of this invention. Neither will all hosts
function equally well with the same expression system. However, one
skilled in the art will be able to select the proper vectors,
expression control sequences, and hosts without undue
experimentation to accomplish the desired expression without
departing from the scope of this invention. For example, in
selecting a vector, the host must be considered because the vector
must function in it. The vector's copy number, the ability to
control that copy number, and the expression of any other proteins
encoded by the vector, such as antibiotic markers, will also be
considered.
[0162] In selecting an expression control sequence, a variety of
factors will normally be considered. These include, for example,
the relative strength of the system, its controllability, and its
compatibility with the particular DNA sequence or gene to be
expressed, particularly as regards potential secondary structures.
Suitable hosts will be selected by consideration of, e.g., their
compatibility with the chosen vector, their secretion
characteristics, their ability to fold proteins correctly, and
their fermentation requirements, as well as the toxicity to the
host of the product encoded by the DNA sequences to be expressed,
and the ease of purification of the expression products.
[0163] Considering these and other factors a person skilled in the
art will be able to construct a variety of vector/expression
control sequence/host combinations that will enable expression the
DNA sequences encoding Mst1 or an antagonist of Mst1, including for
example a mutant and dominant negative Mst1, of this invention on
transduction to animal cells, on infection of animal cells, or on
fermentation or in large scale animal culture.
[0164] It is further intended that Mst1 analogs may be prepared
from nucleotide sequences of the protein complex/subunit derived
within the scope of the present invention. Analogs, such as
fragments, may be produced, for example, by pepsin or other
protease digestion of Mst1 polypeptide. Other analogs, such as
muteins, can be produced by standard site-directed mutagenesis of
Mst1 coding sequences. Analogs exhibiting "Mst1 activity",
including kinase activity, such as small molecules, whether
functioning as promoters or inhibitors, may be identified by known
in vivo and/or in vitro assays.
[0165] As mentioned above, a DNA sequence encoding Mst1 or an
analog, including a dominant negative mutant of Mst1, can be
prepared synthetically rather than cloned. The DNA sequence can be
designed with the appropriate codons for the Mst1 amino acid
sequence. In general, one will select preferred codons for the
intended host if the sequence will be used for expression. The
complete sequence is assembled from overlapping oligonucleotides
prepared by standard methods and assembled into a complete coding
sequence. See e.g., Edge, Nature, 292:756 (1981); Nambair et al.,
Science, 223:1299 (1984); Jay et al., J. Biol. Chem., 259:6311
(1984). Synthetic DNA sequences allow convenient construction of
genes which will express Mst1 analogs or "muteins". Alternatively,
DNA encoding muteins can be made by site-directed mutagenesis of
native Mst1 genes or cDNAs, and muteins can be made directly using
conventional polypeptide synthesis. A general method for
site-specific incorporation of unnatural amino acids into proteins
is described in Christopher J. Noren, Spencer J. Anthony-Cahill,
Michael C. Griffith, Peter G. Schultz, Science, 244:182-188 (April
1989). This method may be used to create analogs with unnatural
amino acids.
[0166] The present invention extends to the preparation of
antisense oligonucleotides, small interfering RNAs (siRNAs), and
ribozymes that may be used to interfere with the expression of Mst1
at the translational level. This approach utilizes antisense
nucleic acid and ribozymes to block translation of a specific mRNA,
either by masking that mRNA with an antisense nucleic acid,
destabilizing it or cleaving it with a ribozyme.
[0167] Antisense nucleic acids are DNA or RNA molecules that are
complementary to at least a portion of a specific mRNA molecule.
(See Weintraub, 1990; Marcus-Sekura, 1988.) In the cell, they
hybridize to that mRNA, forming a double stranded molecule. The
cell does not translate an mRNA in this double-stranded form.
Therefore, antisense nucleic acids interfere with the expression of
mRNA into protein. Oligomers of about fifteen nucleotides and
molecules that hybridize to the AUG initiation codon will be
particularly efficient, since they are easy to synthesize and are
likely to pose fewer problems than larger molecules when
introducing them into Mst1-producing cells. Antisense methods have
been used to inhibit the expression of many genes in vitro
(Marcus-Sekura, 1988; Hambor et al., 1988).
[0168] Ribozymes are RNA molecules possessing the ability to
specifically cleave other single stranded RNA molecules in a manner
somewhat analogous to DNA restriction endonucleases. Ribozymes were
discovered from the observation that certain mRNAs have the ability
to excise their own introns. By modifying the nucleotide sequence
of these RNAs, researchers have been able to engineer molecules
that recognize specific nucleotide sequences in an RNA molecule and
cleave it (Cech, 1988.). Because they are sequence-specific, only
mRNAs with particular sequences are inactivated.
[0169] Investigators have identified two types of ribozymes,
Tetrahymena-type and "hammerhead"-type. (Hasselhoff and Gerlach,
1988) Tetrahymena-type ribozymes recognize four-base sequences,
while "hammerhead"-type recognize eleven- to eighteen-base
sequences. The longer the recognition sequence, the more likely it
is to occur exclusively in the target mRNA species. Therefore,
hammerhead-type ribozymes are preferable to Tetrahymena-type
ribozymes for inactivating a specific mRNA species, and eighteen
base recognition sequences are preferable to shorter recognition
sequences.
[0170] The DNA sequences described herein may thus be used to
prepare antisense molecules against, and ribozymes that cleave
mRNAs for Mst1.
[0171] The use of RNA interference strategies to inhibit the
expression of Mst1 is further embodied in the invention. Thus,
methods of RNA interference and small interfering RNA compositions
are included in the methods and compositions of the present
invention. RNA interference refers to the silencing of genes
specifically by double stranded RNA (dsRNA) (Fine, A. et al (1998)
Nature 391; 806-811). In one embodiment, short or small interfering
RNA (siRNA) is utilized (Elbashir, S. M. et al (2001) Nature
411:494-498). In addition, long double stranded RNA hairpins may be
employed (Tavernarakis, N. et al (2000) Nature Genet. 24:180-183;
Chuang, C. F. and Meyerowitz, E. M. (2000) PNAS USA 97:4985-90;
Smith, N A et al (2000) Nature 407:319-20). Virus-mediated RNA
interference against K-Ras has been described (B rummelkamp, T. R.
et al (2002) Cancer Cell. 2:243-247).
[0172] The invention may be better understood by reference to the
following non-limiting Examples, which are provided as exemplary of
the invention. The following examples are presented in order to
more fully illustrate the preferred embodiments of the invention
and should in no way be construed, however, as limiting the broad
scope of the invention.
EXAMPLE 1
[0173] The studies described herein were undertaken to determine
whether or not Mst1 plays an essential role in mediating apoptosis
in cardiac myocytes, by using both cultured cardiac myocytes in
vitro and transgenic mouse models in vivo. The results demonstrate
that Mst1 is activated not only by genotoxic compounds but also by
clinically relevant pathologic insults in the heart. Stimulation of
Mst1 causes cardiac myocyte apoptosis and dilated cardiomyopathy
without any compensatory cardiac myocyte hypertrophy. Furthermore,
specific inhibition of endogenous Mst1 by dominant negative Mst1
inhibits cardiac myocyte apoptosis and myocardial infarction in
response to I/R. These results indicate that Mst1 plays an
essential role in mediating apoptosis by clinically relevant
pathologic stimuli in the heart and identify Mst1 as an important
therapeutic target in ischemic heart diseases.
Mst1 is a Predominant MBP Kinase Activated by Potent Proapoptotic
Stimuli in Cardiac Myocytes
[0174] Our results suggest that Mst1 is a prominent MBP kinase
activated by potent apoptotic stimuli, including chelerythrine and
calyculin A, in cardiac myocytes. Activation of Mst 1 was also
observed in response to hypoxia/reoxygenation of cardiac myocyte in
vitro and I/R of the mouse heart in vivo. Activation of Mst1 by
such clinically relevant stresses has not been reported previously.
Overexpression of wild type Mst1 was sufficient to cause typical
findings of apoptosis, including cell shrinkage, cytoplasmic
accumulation of mono- and oligo-nucleosomes and activation of
caspase-3 in cardiac myocytes. Cell death induced by wild type Mst1
was suppressed in the presence of the caspase-3 inhibitor. These
results suggest that activation of Mst1 activates caspase-3, which
in turn mediates cardiac myocyte apoptosis. Since cleavage and
activation of Mst1 were at least in part inhibited by the caspase
inhibitors, activation of Mst1 partially depends upon caspases.
Thus, Mst1 and caspase-3 stimulate one another, thereby initiating
a positive feed back mechanism leading to increased apoptosis in
cardiac myocytes. These results suggest that Mst1 can be an
important regulator of apoptosis in cardiac myocytes. This notion
is also well supported by the fact that cardiac myocyte apoptosis
by chelerythrine or calyculin A treatment as well as in response to
I/R was significantly suppressed in the presence of dominant
negative Mst1.
[0175] Recent evidence suggests that Mst1 is activated either by
phosphorylation of the catalytic domain or by caspase-mediated
cleavage of the C-terminal inhibitory domain (42). In fact, Mst1 is
activated by both mechanisms in cardiac myocytes: chelerythrine
causes activation of Mst1 via caspase-dependent cleavage, while
calyculin A causes activation of the full length form of Mst1
possibly through phosphorylation. Since both mechanisms cause
myocyte death, which was inhibited by dominant negative Mst1,
activation of Mst1by either mechanism causes cardiac myocyte
apoptosis. In this regard, it would be interesting to determine, by
using a cleavage resistant form of Mst1, if the cleaved form and
the full-length form of Mst1 cause apoptosis with distinct
morphological characteristics. Interestingly, the active form of
Mst1 in Tg-Mst1 or in control mice subjected to I/R predominantly
exists in the full length form. This indicates that cleavage of
Mst1 by preceded activation of caspase-3 may not be required for
activation of Mst1 in pathological conditions in vivo. Since
partial cleavage of Mst1 was observed when higher doses of AdX-Mst1
were transduced in cardiac myocytes in vitro or I/R was applied to
Tg-Mst1 (data not shown),we speculate that higher levels of . . .
caspase activation is required for the cleavage of Mst1 to be seen.
Since we could detect cleavage of caspase-3 even without cleavage
of Mst1 in Tg-Mst1, caspase 3 may have a higher affinity for
self-cleavage compared with cleavage of Mst1. Alternatively,
activation of caspase-3 and cleavage of Mst1 could co-exist at the
time only when cells are undergoing apoptosis, but anti-cleaved
caspase-3 antibody may be more sensitive for detection of the
cleaved product.
[0176] The pattern of Mst1 activation by overexpression or by I/R
is analogous to that by calyculin A, a phosphatase inhibitor. In
this regard, it will be interesting to examine if the activation
loop of Mst1 is phosphorylated in Tg-Mst1 or in response to I/R
(42). It has been reported that transgenic mice overexpressing an
inhibitor of PP-2A exhibited dilated cardiomyopathy (43). It would
be interesting to examine if the activation of Mst1 is involved in
development of heart failure in these animals.
Cardiac Specific Overexpression of Mst1 Stimulates Cardiac Myocyte
Apoptosis and Induces Dilated Cardiomyopathy
[0177] Cardiac specific overexpression of wild type Mst1 caused
dilation in all 4 chambers, wall thinning, and reduced
bi-ventricular function, consistent with findings of dilated
cardiomyopathy. Interestingly, hypertrophy of surviving ventricular
cardiac myocytes was not observed. To our knowledge, Mst1 is unique
among protein kinases thus far overexpressed in the mouse heart in
vivo, because overexpression of Mst1 in the heart primarily causes
dilated cardiomyopathy without inducing cardiac myocyte
hypertrophy. It should be noted that although cardiac function was
generally reduced, some variability was observed in the severity of
congestive heart failure among transgenic littermate. This suggests
that other genetic modifiers may exist to regulate the
susceptibility of mice to congestive heart failure.
[0178] We asked what is the cause of dilated cardiomyopathy. in
Tg-Mst1l? We found that Tg-Mst1 have an increased number of TUNEL
positive cells, which was accompanied by increased levels of
caspase-3 activity. Although whether the TUNEL positive cells in
Tg-Mst1 represent apoptosis or oncosis remains to be elucidated,
since Mst1 promotes cell death consistent with apoptosis in vitro,
it is likely that Tg-Mst1 mice have more apoptosis. Considering the
fact that increases in TUNEL positive myocytes and interstitial
fibrosis were observed even before the animals manifest overt sign
of heart failure, increases in apoptosis may be the primary cause
of dilated cardiomyopathy. This notion is also supported by the
fact that contraction and relaxation function of single cardiac
myocytes isolated from Tg-Mst1 with decreased LVEF were preserved.
Thus, we propose that decreases in the number of total cardiac
myocytes in the heart (due to increases in apoptosis) at least in
part may contribute to initial development of dilated
cardiomyopathy in Tg-Mst1.
[0179] It has been suggested that Mst1 is a MAP4K and regulates
downstream stress activated protein kinases, such as JNK and p38.
The activated form of Mst1 is translocated to the nucleus and
potentially affects nuclear components of the apoptosis machinery,
including ICAD (Inhibitor of Caspase-Activated DNase) (31,32,42).
However, the targets of Mst1 mediating its proapoptotic effects in
cardiac myocytes remain to be elucidated. Genomic analyses of
Tg-Mst1 indicated that some components of nuclear encoded
mitochondrial cytochrome c oxidase are downregulated. It has been
shown that mitochondrial DNA encoded cytochrome c is downregulated
in the failing mouse heart possibly due to DNA damage caused by
increased levels of reactive oxygen species (44). It has been
suggested that downregulation of cytochrome c oxidase causes severe
impairment of mitochondrial ATP production as well as increased
production of reactive oxygen species, a potent inducer of
apoptosis (45). It should be noted that reduction of mRNA of some
components of cytochrome c oxidase was observed in young Tg-Mst1
mice, which yet showed overt sign of congestive heart failure.
Thus, we propose that downregulation of cytochrome c oxidase is at
least in part involved in the pathogenesis of DCM in Tg-Mst1. It
should be noted that downregulation of cytochrome c oxidase is not
necessarily the common feature of congestive heart failure. Thus,
this may be a unique downstream target of Mst1. The precise
signaling mechanism connecting Mst1 and reduced cytochrome c
oxidase expression remains to be elucidated.
[0180] Our results suggest that Mst1 is a MAP4K and regulates
downstream SRPKs, such as p38-MAPK and p46-JNKs in cardiac
myocytes. Whether or not p38-MAPK and/or p46-JNKs mediate
proapoptotic effects of Mst1 is of great interest. The activated
form of Mst1 is translocated to the nucleus and may affect
Death-associated protein 4 (DAP4) (51) and the nuclear components
of the apoptosis machinery, including ICAD (Inhibitor of
Caspase-Activated DNase) (31, 32, 42). Although Mst1 efficiently
phosphorylates MBP at least in vitro, patho-physiologically
relevant substrates of Mst1, mediating the proapoptotic effect of
Mst1, remain to be elucidated in cardiac myocytes.
Cardiac Specific Overexpression of Mst1 Prevents Compensatory
Cardiac Myocyte Hypertrophy and Potentially Obscures Operation of
the Frank-Starling Mechanism in Individual Cardiac Myocytes
[0181] One of the most surprising findings in this study was that
hypertrophy of surviving ventricular cardiac myocytes was not
observed in Tg-Mst1. To our knowledge, Mst1 is unique among protein
kinases thus far overexpressed in the mouse heart in vivo, because
overexpression of Mst1 in the heart primarily stimulates cardiac
myocyte death without compensatory hypertrophy. Absence of cardiac
hypertrophy not only leaves the wall stress elevated but also fails
to compensate for the loss of cardiac mass caused by apoptosis in
Tg-Mst1. Importantly, the longitudinal length as well as the cell
volume of isolated LV myocytes were significantly smaller in
Tg-Mst1. Although increases in myocyte length are commonly observed
in dilated cardiomyopathy, to our knowledge, decreases in cell
volume or cardiac myocyte length in dilated cardiomyopathy have not
been previously reported. We speculate that side-to-side slippage
of cardiac myocytes (49), rather than elongation of individual
myocytes, supports ventricular dilation in Tg-Mst1. Thus, increased
tension development in dilated hearts according to the
Frank-Starling would become less efficient at a single cell level
in Tg-Mst1, which may further contribute to decreased cardiac
function in these animals.
[0182] At present, we are not certain why compensatory cardiac
myocyte hypertrophy does not take place in Tg-Mst1 despite elevated
wall stress. Mst1 may inhibit signaling molecules causing
hypertrophy through either direct phosphorylation or
caspase-mediated cleavage. Little is known as to the cellular
actions of Mst1 besides apoptosis. If Mst1 possess such direct
anti-hypertrophic function, this would be a novel function of Mst1.
Alternatively, ongoing cell proliferation could make cardiac
myocytes smaller (17). In this regard, whether or not increased
cell death stimulates myocyte proliferation in Tg-Mst1 remains to
be elucidated.
Mst1 Plays an Important Role in Mediating Cardiac Myocyte Death in
Response to I/R in the Heart
[0183] Although endogenous Mst1 is activated by proapoptotic
stimuli in both neonatal rat cardiac myocytes and adult mouse
heart, one may argue that overexpression of Mst1 causes
unphysiological responses. In order to address this issue, we
tested the effect of dominant negative Mst1 (K59R) and confirmed
that it was able to suppress the activity of endogenous Mst1 in
baseline and in response to I/R. Most importantly, cardiac specific
expression of dominant negative Mst1 significantly reduced the
extent of myocardial infarction. Since increases in both TUNEL
positive cells and DNA laddering by I/R were significantly
suppressed in Tg-Mst1 (K59R), inhibition of endogenous Mst1 most
likely reduced cardiac myocyte apoptosis. We cannot completely
exclude the possibility that overexpression of Mst1 (K59R) may
affect activities of other protein kinases. However, since Mst1 is
a predominant MBP kinase activated by I/R, the effect of the Mst1
(K59R) is most likely mediated through-inhibition of Mst1 or that
of the closely related Mst 1 family. Our results clearly indicate
that inhibition of Mst1 effectively reduces cardiac myocyte death
by I/R. Mst1 and caspase stimulate one another, thereby forming a
positive feedback loop. Thus, inhibiting the key molecule
facilitating this amplification loop would effectively block
promotion of apoptosis. It has been recently shown that NORE, a
noncatalytic polypeptide homologous to the putative tumor
suppressor RASSF1, associates with Mst1 and the NORE-Mst1 complex
mediates Ras-dependent apoptosis in fibroblasts (46). Thus, Mst1
may be involved in a wide variety of extracellular stimuli as well
as environmental stresses. In this regard, Mst1 could be an
important therapeutic target in many cardiovascular diseases.
Mst1 is a Predominant MBP Kinase Activated by Potent Stimulators of
Apoptosis in Cardiac Myocytes
[0184] In order to identify the signaling mechanism inducing
apoptosis in cardiac myocytes, cardiac myocytes were treated with
chelerythrine, a potent inducer of apoptosis (35). The whole cell
extracts prepared from chelerythrine-treated myocytes were
subjected to in gel kinase assays, using myelin basic protein as a
substrate (35). We found that a 34 kD kinase is most prominently
activated by chelerythrine at 6-30 .mu.M, the concentrations where
apoptosis and activation of caspase-3 are observed (35). Activation
of the 34 kD kinase was accompanied by disappearance of a 61 kD
kinase (FIG. 1A). Since it has been shown in other cell types that
Mst1, a 61kD kinase, is cleaved by caspases and a resultant 34 kD
fragment containing the N-terminal kinase domain becomes active, we
examined if the 61kD and 34 kD proteins are Mst1 in our
experiments. Immune complex kinase assays, using specific anti-Mst1
antibody raised against the N-terminal 15 amino acids of Mst1,
indicated that the 34 kD form of Mst1 is activated by the
chelerythrine treatment (FIG. 1B). Furthermore, immunoblot
analyses, using specific anti-Mst1 antibodies, indicated that the
61kD form of Mst1 is downregulated, while the 34 kD form of Mst1 is
concomitantly upregulated after chelerythrine treatment (FIG. 1C),
consistent with the changes in activities of the 61 and 34 kD
proteins in the in-gel kinase assays. In order to examine if Mst1
is activated by a caspase-dependent cleavage in cardiac myocytes,
we transduced cardiac myocytes with XIAP, which we have shown
inhibits apoptosis and activation of caspase-3 in cardiac myocytes
(35). Activation and cleavage of Mst1 was completely inhibited in
the presence of XIAP (FIG. 1B), suggesting that Mst1 is activated
by caspase-dependent cleavage in cardiac myocytes. Cleavage and
activation of Mst-1 is also induced by hypoxia/reoxygenation, a
known stimulus of apoptosis in cardiac myocytes (FIG. 1D).
[0185] Recent evidence suggests that Mst1 is also activated by
phosphorylation of the activation loop even in the absence of
cleavage (42). Calyculin A, an inhibitor of protein phosphatase 2A
(PP-2A) and PP-1, causes prominent cell death consistent with
apoptosis in cardiac myocytes, which is evidenced by significant
increases (4.3.+-.1.4 fold, n=4, p<0.05 vs untreated) in
cytoplasmic accumulation of oligo- and mono-nucleosomes. In gel
kinase assays indicated that a 61 kD form of Mst1 is strongly
activated by calyculin A without activation of the 34 kD form (FIG.
1E). These results suggest that Mst1 is a prominent MBP kinase,
which is activated by potent apoptotic stimuli full length (61 kD)
forms, is accompanied by prominent cell death in cardiac
myocytes.
EXAMPLE 2
Mst1 Plays an Essential Role in Mediating Apoptosis in Response to
Chelerythrine and Calyculin A in Cardiac Myocytes
[0186] In order to examine if Mst1 promotes apoptosis, we
overexpressed either wild type Mst1 or dominant negative Mst1
(Mst1(K59R)) in cardiac myocytes by using adenovirus transduction.
Immunoblot analyses with anti-Mst1 antibody indicated that
transduction of adenovirus harboring wild type Mst1 (AdX-Mst1)
dose-dependently increased the full length form of Mst1. Expression
of the cleaved form of Mst1 was also observed at high doses,
suggesting that overexpression of Mst1 alone can induce partial
cleavage of Mst1 (FIG. 2A). By contrast, transduction of adenovirus
harboring Mst1(K59R) (AdX-DN-Mst1) increased only the full length
form of Mst1(K59R) (FIG. 2B). In gel kinase assays showed that the
MBP kinase activity of Mst1 was significantly increased by
overexpression of wild type Mst1, while it was not activated by
Mst1 (K59R), confirming that Mst1(K59R) is kinase inactive (FIG.
2C). Furthermore, increased activities and cleavage of Mst1 by
overexpression of Mst1 were attenuated in the presence of a
caspase-3 inhibitor, DEVD-CHO, suggesting that Mst1 activates
caspase-3, which in turn causes cleavage of Mst1 (FIG. 2C, lane 4).
Transduction of either control virus or AdX-DN-Mst1 did not induce
any significant changes in the morphology of cardiac myocytes. By
contrast, transduction of AdX-Mst1 caused shrinkage and cell death
in cardiac myocytes (FIG. 2D). Cytoplasmic accumulation of mono-
and oligo-nucleosomes, sensitive indicators of nuclear
fragmentation by apoptosis, was dose-dependently increased by
overexpression of wild type Mst1 but not by control virus or Mst1
(K59R) (FIG. 2E). Increases in DNA fragmentation by wild type Mst1
were inhibited in the presence of DEVD-CHO (FIG. 2F).
Overexpression of wild type Mst1, but not Mst1 (K59R), caused
activation of caspase-31 which was determined by immunoblotting
with anti-cleaved specific caspase-3 antibody (FIG. 2G). These
results suggest that Mst1 induces cardiac myocyte apoptosis in its
kinase activity-dependent manner.
[0187] In order to examine if Mst1 is required for cardiac myocyte
apoptosis in response to chelerythrine, cardiac myocytes were
transduced with AdX-DN-Mst1 or control virus and challenged by
chelerythrine. Cytoplasmic accumulation of mono- and
oligo-nucleosome by chelerythrine treatment was significantly
suppressed in the presence of AdX-Mst1(K59R) but not by control
virus (FIG. 3). DNA fragmentation by calyculin A was also inhibited
by AdX-Mst1 (K59R) (5.6 fold with control virus vs 0.9 fold with
AdX-DN-Mst1. These results suggest that both cleaved and full
length forms of Mst1 plays a critical role in mediating apoptosis
in cardiac myocytes.
EXAMPLE 3
Cardiac Specific Overexpression of Mst1 in Mice Causes Dilated
Cardiomyopathy Without Cardiac Myocyte Hypertrophy
[0188] In order to examine the function of Mst1 in the mouse heart
in vivo, transgenic mice with cardiac specific overexpression of
wild type (Tg-Mst1) was generated by using the .quadrature.MHC
promoter. We identified three founders with transgene positive by
Southern blot analyses. Among them, germ line transmission was
observed in two lines. One line (line #28) showed prominent cardiac
specific overexpression of wild type Mst1, while the other line
(line #8) showed modest overexpression (FIG. 4A). We confirmed that
Mst1 is overexpressed predominantly in the heart as expected (FIG.
4B). In-gel MBP kinase assays indicated that the total activity of
Mst1 is significantly increased in Tg-Mst1. Increases in the MBP
kinase activity in Tg-Mst1 were found predominantly in the full
length form rather than in the cleaved form (FIG. 4C).
[0189] Interestingly, some Tg-Mst1 exhibited overt signs of heart
failure, such as shortness of breath and edema, and died
prematurely as early as on Day 15. Echocardiographic measurements
of Tg-Mst1 lines #28 and #8 at 70-80 days old indicated that
Tg-Mst1 exhibited significant increases in LVEDD and LVESD and
significant decreases in LVEF, LV fractional shortening and LV wall
thickness (TABLE 1). TABLE-US-00002 TABLE 1 Echocardiographic
Analyses of Tg-Mst1 Non-transgenic Tg-Mst1 (n = 4) (n = 5) Line #28
(High level overexpression) Age (days old) 75 .+-. 2.89 76 .+-.
2.45 LVEDD (mm) 3.92 .+-. 0.11 4.39 .+-. 0.06* LVESD (mm) 2.62 .+-.
0.11 3.55 .+-. 0.10* LVEF (%) 70.0 .+-. 1.83 47.2 .+-. 2.80* % FS
(%) 33.1 .+-. 1.44 19.2 .+-. 1.41* DSEP WT (mm) 0.59 .+-. 0.04 0.39
.+-. 0.01* DPW WT (mm) 0.59 .+-. 0.02 0.37 .+-. 0.03* HR (bpm)
246.8 .+-. 23.4 303.0 .+-. 32.8 *p < 0.01 compared with
non-transgenic Line #8 (Intermediate level overexpression) Age
(days old) 195 .+-. 1.96 193 .+-. 1.96 LVEDD (mm) 4.40 .+-. 0.25
4.54 .+-. 0.28 LVESD (mm) 2.99 .+-. 0.14 3.29 .+-. 0.19 LVEF (%)
68.4 .+-. 1.21 61.6 .+-. 2.38* % FS (%) 31.9 .+-. 0.78 27.5 .+-.
1.46* DSEP WT (mm) 0.68 .+-. 0.02 0.64 .+-. 0.03 DPW WT (mm) 0.65
.+-. 0.02 0.63 .+-. 0.02 HR (bpm) 258.2 .+-. 8.1 255.8 .+-. 25.2 *p
< 0.05 compared with non-transgenic
[0190] Hemodynamic analyses conducted in Tg-Mst1 with
(echocardiographically determined) reduced LVEF confirmed that
LVEDP was significantly elevated, while LV dP/dt was decreased
compared with non-transgenic littermates (TABLE 2). TABLE-US-00003
TABLE 2 Hemodynamic Measurements of Tg-Mst1 Non-transgenic (n = 4)
Tg-Mst1 (n = 5) Age (days) 80 .+-. 7.8 88 .+-. 12 LVSP (mmHg) 84
.+-. 2.3 70 .+-. 5.1 LVEDP (mmHg) 3.3 .+-. 2.9 18.6 .+-. 1.5** +LV
dP/dt 5200 .+-. 245 4300 .+-. 663 -LV dP/dt 4467 .+-. 356 3080 .+-.
481 RVSP (mmHg) 18 .+-. 2.9 29 .+-. 3.3* RVEDP (mmHg) 0.7 .+-. 0.4
9.0 .+-. 2.2* RAP (mmHg) 1.3 .+-. 0.4 7.0 .+-. 2.3 HR (bpm) 323
.+-. 54 297 .+-. 36 *p < 0.05, **p < 0.001 compared with
non-transgenic
[0191] Necropsy of Tg-Mst1 performed at 1-2 months indicated
dilation of all 4 cardiac chambers, mural thrombus formation with
occasional fibrous structures in both atriums, and reduced wall
thickness, consistent with the findings of dilated cardiomyopathy
(TABLE 3 and FIG. 4D). Although LA and RA weight/body weight of
Tg-Mst1 was significantly higher than that of non-transgenic
littermate, LV weight/body weight and RV weight/body weight were
not significantly different between Tg-Mst1 and non-transgenic
littermate (TABLE 3). Significant increases in lung weight/body
weight and liver weight/body weight and visible congestion of the
liver were observed in Tg-Mst1 compared with non-transgenic
littermate (TABLE 3 and FIG. 4E). The lungs were congested (FIG.
4F). Histological analyses of the heart sections indicated that
TUNEL positive myocytes are significantly increased in Tg-Mst1
(control 0.06.+-.0.03%, Tg-Mst1 0.30.+-.0.05%, n=4, p<0.01). The
level of interstitial fibrosis significantly increased in all four
chambers of Tg-Mst1 (FIG. 4G). These results suggest that myocyte
death and subsequent replacement of myocardium with fibrous tissue
took place in Tg-Mst1 hearts. Interestingly, the cross sectional
areas of cardiac myocytes in the LV was not significantly different
between Tg-Mst1 and non-transgenic mice confirming that there was
no compensatory cardiac myocyte hypertrophy in Tg-Mst1 (FIG. 4H).
The level of-cleaved caspase-3 was-increased in hearts of Tg-Mst1
(FIG. 4I). Although it was smaller in extent, reduced cardiac
function and increased levels of cardiac myocyte apoptosis were
also found in line #8 of Tg-Mst1. TABLE-US-00004 TABLE 3 Postmortem
Pathologic Measurements of Tg-Mst1 Non-transgenic Tg-Mst1 (n = 9)
(n = 12) Age (days) 46.7 .+-. 2.7 46.9 .+-. 1.9 Body weight (g)
18.4 .+-. 0.4 19.4 .+-. 0.8 LV (mg) 64.2 .+-. 2.0 64.5 .+-. 2.6 RV
(mg) 19.1 .+-. 0.8 20.6 .+-. 0.6 LV/body weight 3.48 .+-. 0.07 3.32
.+-. 0.06 Lung/body weight 6.67 .+-. 0.30 7.73 .+-. 0.29*
Liver/body weight 47.6 .+-. 1.78 55.1 .+-. 2.71* *p < 0.05
compared with non-transgenic **p < 0.01 compared with
non-transgenic
EXAMPLE 4
Contractile Function of Individual Cardiac Myocytes Isolated from
Tg-Mst1 is not Altered
[0192] In order to examine the mechanism of reduced cardiac
function in Tg-Mst1, cardiac myocytes were isolated from 3 months
old Tg-Mst1 and non-transgenic control mice and their contractile
properties were evaluated by using the edge detection method. Echo
cardiographic measurements indicated that LVEF of the Tg-Mst1 mice
used in these experiments was significantly lower than that of
non-transgenic mice (Tg-Mst1 51.+-.5% vs non-transgenic littermate
68.+-.1%, p<0.05, n=4). There were no significant differences in
% contraction and the rate of relaxation of isolated cardiac
myocytes between Tg-Mst1 and non-transgenic mice (FIG. 5),
suggesting that the decreases in cardiac contractility in Tg-Mst1
may not be primarily caused by decreases in the contractile or
relaxation function of individual- cardiac myocytes. Interestingly,
the length of ventricular myocytes isolated from Tg-Mst1 was
smaller than those from non-transgenic controls.
EXAMPLE 5
Expression of Nuclear Encoded Cytochrome c Oxidase is Reduced in
Tg-Mst1
[0193] In order to examine the mechanism of dilated cardiomyopathy
in Tg-Mst1, we performed DNA microarray analyses. PolyA RNA was
isolated from the hearts of Tg-Mst1 and non-transgenic littermate
at the age of 2 months, those who did not show overt signs of
congestive heart failure. The list of the genes, whose expression
was consistently upregulated or downregulated in three independent
analyses, is shown in TABLE 4. Classification of the identified
genes according to their function indicates that many genes
regulating both mitochondrial and cytoplasmic metabolism are
downregulated in Tg-Mst1. Among them, we found that some components
of nuclear encoded cytochrome c oxidase subunits are consistently
downregulated by 21-64%. Exemplary RT-PCR results are shown in FIG.
8 which demonstrates that mRNA expression of PGC-1.alpha. and
PGC-1.beta. are each decreased in transgenic Tg-Mst1 mice. PGC-1 is
a nuclear transcription co-factor which plays an important role in
regulating expression of nuclear encoded mitochondrial genes.
Proteomic analysis, although more limited in scope, showed similar
results. In particular and exemplary of the protein analysis, FIG.
9 shows Western blots and tabulated expression of Cytochrome C
oxidase complex proteins COX VIIa, COX IV and COX Vb in transgenic
versus non-transgenic animals. TABLE-US-00005 TABLE 4 Genes
consistently upregulated or downregulated in Tg-Mst1 in three
independent microarray analyses mean % change SEM Upregulated genes
matrix gamma carboxylglutamate protein 584 270 procollagen 1 alpha
1 subunit 702 457 peptidylprolyl isomerase A 77 12 natriuretic
peptide precursor type B 819 278 desmin 199 95 Downregulated genes
Mitochondrial metabolism COX7A1 -74 15 COX7C -59 11 COX4 -47 20
COX5B -55 12 COX8B -54 18 ATPase inhibitor -12 4 mitochondrial
malate dehydrogenase -53 10 soluble malate dehydrogenase -43 14
NADH dehydrogenase flavoprotein 1 -52 2 NADH-ubiquinone
oxidoreductase MWFE -54 24 subunit Cytoplasmic metabolism gamma
neuronal enolase 2 -62 8 muscle creatine kinase -72 4 lactate
dehydrogenase 2B subunit -40 8 soluble superoxide dismutase 1 -28 4
prosaposin -85 10 Others vascular endothelial growth factor B -47 8
cardiac troponin I -59 11 la-associated invariant chain -64 25
EXAMPLE 6
Cardiac Specific Overexpression of Mst1 (K59R) Works as Dominant
Negative Mst1 and Significantly Reduces Myocardial Infarction and
Apoptosis in Response to I/R
[0194] In order to examine if Mst1 plays a critical role in
mediating apoptosis in response to pathologic insults to the
hearts, we generated transgenic mice with cardiac specific
overexpression of dominant negative Mst1 (Mst1 (K59R))
(Tg-DN-Mst1). Among three lines generated, line #10 expressed the
highest level of Mst1(K59R) in the heart (FIG. 6A). Tg-DN-Mst1 did
not show premature death or any signs of heart failure. The results
of echocardiographic measurements of Tg-DN-Mst1 were not
significantly different from those of non-transgenic littermates
(TABLE 5). These results suggest that development of dilated
cardiomyopathy in Tg-Mst1 is dependent upon the kinase activity of
Mst1. In order to examine if overexpression of Mst1(K59R) works as
dominant negative, we applied 20 min of ischemia and subsequent 24h
of reperfusion into the mouse heart. Results of the in gel MBP
kinase assays showed that I/R activates Mst1 primarily in the full
length form in the control mouse hearts (FIG. 6B). By contrast,
activities of Mst1 at basal conditions as well as in response to
I/R were abolished in Tg-DN-Mst1, suggesting that cardiac specific
overexpression of Mst1(K59R) works as dominant negative for
endogenous Mst1 (FIG. 6C). The extent of myocardial infarction in
response to I/R, quantitated by the TTC staining of the area at
risk, was significantly smaller in Tg-DN-Mst1 compared with that in
non-transgenic littermate. The heart section obtained from the
ischemic area of Tg-DN-Mst1 exhibited a smaller number of TUNEL
positive myocytes compared with that of non-transgenic littermate
(FIG. 6D). Electrophoresis of genomic DNA prepared from the
ischemic area of non-transgenic mice exhibited a typical pattern of
DNA laddering. By contrast, DNA laddering was significantly
suppressed in Tg-DN-Mst1 (FIG. 6E). These results suggest that
inhibition of Mst1 reduces both cardiac myocyte apoptosis and the
size of myocardial infarction in mouse hearts. TABLE-US-00006 TABLE
5 Echocardiographic Analyses of Tg-DN-Mst1 NTg (n = 9) TG-DN-Mst1
(n = 8) Age (days) 92 .+-. 5.5 102 .+-. 4.7 BW (g) 23 .+-. 0.6 22
.+-. 1.0 DSWT (mm) 0.6 .+-. 0.03 0.6 .+-. 0.02 LVDD (mm) 3.6 .+-.
0.11 3.9 .+-. 0.08 DPWT (mm) 0.6 .+-. 0.03 0.6 .+-. 0.03 LVSD (mm)
88 .+-. 6 87 .+-. 5 % EF (%) 68 .+-. 1.2 70 .+-. 0.9 % FS (%) 32
.+-. 0.9 33 .+-. 0.6 HR (bpm) 271 .+-. 16 231 .+-. 26
EXAMPLE 7
[0195] We further examined the mechanism by which Mst1 stimulates
apoptosis in cardiac myocytes. Transduction of Mst1 (Tg-Mst1)
significantly (two fold, n=3, P<0.05) increased the amount of
cytochrome c in the mitochondria-free cytosolic fraction compared
with that of control virus, suggesting that release of cytochrome c
may contribute to the proapoptotic effect of Mst1 (FIG. 7A).
Transduction of Mst1 modestly activated p38-MAPK and p46-JNKs
(FIGS. 7B and 7C), while that of the dominant negative Mst1
(Tg-DN-Mst1) abolished chelerythrine-induced activation of p38-MAPK
in cardiac myocytes (FIG. 7D). These results suggest that Mst1
works as MAP4K in cardiac myocytes and that it plays an important
role in mediating activation of p38-MAPK by chelerythrine.
EXAMPLE 8
Mst1 Directly Inhibits Cardiac Hypertrophy
[0196] We have previously and above shown that mammalian sterile-20
like kinase 1 (Mst1) plays an important role in mediating cardiac
myocyte apoptosis in response to ischemia/reperfusion and
doxorubicin treatment. Cardiac specific overexpression of Mst1 in
transgenic mice (Tg-Mst1) increases cardiac myocyte apoptosis in
the heart and the mice develop dilated cardiomyopathy (DCM).and
congestive heart failure within 3 months of age. Surprisingly,
histological analyses of the left ventricular (LV) cardiac myocyte
cross sectional area and measurements of the longitudinal length of
isolated ventricular cardiac myocytes indicated that there was no
compensatory cardiac myocyte hypertrophy in Tg-Mst1 and that
myocytes are actually shorter despite elevated wall stress caused
by DCM. Lack of compensatory cardiac myocyte hypertrophy may
adversely affect LV function of Tg-Mst1 because operation of the
Frank Starling mechanism could be less efficient at the individual
cell level. This study was undertaken in order to elucidate if
transient expression of Mst1 has a direct anti-hypertrophic effects
in cultured cardiac myocytes in vitro. Neonatal rat cardiac
myocytes were transduced with adenoviral vectors (10 MOI) in
serum-free conditions for 48 h and then treated with phenylephrine
(PE, 10 .mu.M) for 48 h. Phenylephrine stimulates hypertrophy of
cardiac myocytes in normal animals. Treatment of LacZ
virus-transduced myocytes with PE caused a 2.4 fold increase in the
cell size and a 1.7 fold increase in protein/DNA content. By
contrast, transduction of adenovirus harboring Mst1 completely
inhibited PE-induced increases in cell size and protein/DNA
content. Mst1 also inhibited PE-induced increases in mRNA
expression of atrial natriuretic factor by 49%. Interestingly, Mst1
inhibited PE-induced (10 min treatment) activation of ERK by 28%.
In summary, Mst1 has a direct anti-hypertrophic effect upon
PE-treated cultured cardiac myocytes, possibly affecting other
signaling mechanisms, including ERKs. Our results suggest that the
proapoptotic signaling mechanism can directly affect hypertrophic
signaling mechanisms, thereby contributing to the pathogenesis of
cardiomyopathy.
EXAMPLE 9
Mst1 Plays an Essential Role in Mediating Cardiac Myocyte Apoptosis
by Doxorubicin and Doxorubicin-Induced Cardio-Toxicity
[0197] Mst1 is an ubiquitously expressed serine-threonine kinase,
which is activated by caspase-mediated cleavage and promotes
apoptosis in many cell types, including cardiac myocytes.
Doxorubicin (Dox or Doxo) belongs to the anthracycline class of
anticancer drugs. The limiting factor in the clinical use of Dox is
the fact that it induces dose-dependent and irreversible
cardiomyopathy. Recent evidence suggests that Dox induces cardiac
myocyte apoptosis, which may contribute to the cardiotoxicity of
this compound. However, the signaling mechanism of cardiac myocyte
apoptosis by Dox is not well understood. We hypothesized that Mst1
mediates cardiac myocyte apoptosis by Dox. In order to address this
issue, we used neonatal rat cardiac myocyte cultures and adenovirus
transduction. Treatment of cardiac myocytes with Dox (0.1-3 .mu.M)
dose-dependently induced cell shrinkage within 6h (FIG. 10), which
was accompanied by activation of caspase-3 and DNA fragmentation,
which was determined by cytoplasmic accumulation of mono- and
oligo-nucleosome (FIGS. 11 and 12). These results suggest that Dox
induces apoptosis in cardiac myocytes. Immunoblot analyses
indicated that Mst1 is cleaved to form a 34 kD fragment after 6h
treatment with Dox at 0.1-3 .mu.M (FIG. 16). Immunoblot analysis
also demonstrated cleavage of caspase-3 and caspase-9, to activate
these enzymes in a time dependent manner on treatment with Dox
(FIGS. 13 and 14). In-gel kinase assays, using myelin basic protein
as a substrate, showed that cleavage of Mst1 is accompanied by
activation of Mst1 (FIG. 15). Interestingly, adenovirus-mediated
transduction of dominant negative Mst1 significantly reduced cell
shrinkage and DNA fragmentation by Dox treatment, while that of
control virus showed no effects (OD405 values after 6h treatment
with 0.5 .mu.M Dox: control virus 0.69 vs dominant negative Mst1
virus 0.21) (FIG. 18). Dominant negative Mst1 mice receiving Dox
maintain ejection fraction and % functional shortening when
compared to their non-transgenic littermates (FIGS. 19 and 20). In
summary, Mst1 is activated by Dox in cardiac myocytes. Mst1 plays
an important role in mediating Dox-induced cardiac myocyte
apoptosis. Mst1 may be an important therapeutic target of
Dox-induced cardiomyopathy.
EXAMPLE 10
Mst1 Plays a Critical Role in Cardiac Remodeling
[0198] Overexpression of dominant negative Mst1 (Tg-DN-Mst1)
inhibits cardiac dilation and left ventricular dysfunction after
myocardial infarction. Myocardial infarction was generated by
ligation of the left coronary artery in vivo in normal and
Tg-DN-Mst1 transgenic mice. The results are depicted in FIG. 23.
FIG. 23A (left panel) indicates that a similar size of myocardial
infarction was created by ligation of the left coronary artery in
non-transgenic (NTG) and transgenic (Tg-DN-Mst1) mice. LVEDD (FIG.
23B) and LVEF (FIG. 23C) were measured in sham operated and MI
mice. The results suggest that dominant negative Mst1 may prevent
cardiac dysfunction in post-MI patients.
Materials and Methods
Materials
[0199] Chelerythrine chloride, calyculin A and a caspase-3
inhibitor DEVD-CHO were purchased from Biomol (Plymouth Meeting,
Pa.).
Primary Culture of Neonatal Rat Ventricular Myocytes
[0200] Primary cultures of ventricular cardiac myocytes were
prepared from 1-day-old Crl: (WI) BR-Wistar rats (Charles River
Laboratories, Wilmington, Mass.) as described previously (34). A
cardiac myocyte rich fraction was obtained by centrifugation
through the discontinuous Percoll gradient as described (34). Cells
were cultured in the cardiac myocyte culture medium containing
Dulbecco's modified Eagle medium (DMEM)/F12 supplemented with 5%
horse serum, 4 .mu.g/mL transferrin, 0.7 ng/mL sodium selenite
(GIBCO), 2 g/L bovine serum albumin (fraction V), 3 mmol/L pyruvic
acid, 15 mmol/L HEPES, 100 .mu.mol/L ascorbic acid, 100 .mu.g/mL
ampicillin, 5 .mu.g/mL linoleic acid and 100 .mu.mol/L
5-bromo-2'-deoxyuridine (Sigma). We obtained myocyte cultures in
which more than 95% were myocytes, as assessed by
immunofluorescence staining with a monoclonal antibody against
sarcomeric myosin (MF20). Culture media were changed to serum-free
at 24-36 h and then subjected to adenovirus transduction. Myocytes
were cultured in the serum-free condition for 48 h before
experiments.
Construction of the Adenoviral Vectors
[0201] We constructed recombinant adenovirus by using an Adeno-X
adenovirus construction kit according to the manufacturer's
instruction (Clontech, Palo Alto, Calif.). We made replication
defective human adenovirus type 5 (devoid of E1 and E3) harboring
wild type Mst1 (AdX-Mst1) and dominant negative Mst1
(AdX-Mst1(K59R)). Adenovirus harboring .beta.-galactosidase (Ad5
.beta.gal) was used as a control. Generation of adenovirus
harboring XIAP (Ad5 XIAP) has been described (35). The method of
adenovirus transduction has been described (35).
Analysis of DNA Fragmentation by ELISA and DNA Laddering Assays
[0202] Histone-associated DNA fragments were quantified by the Cell
Death Detection ELISA (Roche, Indianapolis, Ind.) according to the
manufacturer's instruction as described (35) with minor
modification for sample preparation. In brief, myocytes were rinsed
with PBS three times in order to remove nucleosomes leaked out from
necrotic cells and then incubated with the lysis buffer for 30 min.
The supernatant containing mono- and oligonucleosomes from the
cytoplasmic fraction of apoptotic cells was used for further
analyses. DNA fragmentation of the tissue samples was determined by
DNA laddering assays. Genomic DNA containing small molecular weight
fragments was isolated and analyzed by agarose gel electrophoresis
as described (36).
Immunoblot Analysis
[0203] For analyses of Mst1, cells were lysed in a Lysis Buffer A,
containing 25 mmol/L NaCl, 25 mmol/L Tris (pH 7.4), 1 mmol/L
Na.sub.3VO.sub.4, 10 mmol/L NaF, 10 mmol sodium pyrophosphate, 0.5
mmol/L EGTA, 0.5 mmol/L AEBSF, 0.5 .mu.g/mL leupeptin, 0.5 .mu.g/mL
aprotinin. Samples containing the equal amount of protein were
subjected to SDS-PAGE. Proteins were transferred onto
polyvinylidene fluoride microporous membranes (Bio Rad, Hercules,
Calif.) and probed with primary antibodies. We used anti-Mst1
monoclonal antibody (Transduction Laboratory, Lexington, Ky.) for
detection of the carboxyl terminus of Mst1. Affinity purified
rabbit polyclonal antibody was raised against amino-terminal
ETVQLRNPPRRQLKC (pAb-15) (BioSource International, Camarillo,
Calif.) for detection of the amino-terminus of Mst1. Blots were
then probed by horseradish peroxidase-conjugated anti-mouse IgG or
anti-rabbit IgG (Cell Signaling Technolog Inc., Beverly, Mass.).
Antigen-antibody complexes were visualized by the enhanced
chemiluminescence system (ECL, Amersham/Pharmacia, Piscataway,
N.J.). Polyclonal antibodies raised against cleaved caspase-3 (Cell
Signaling Technology Inc.) were used to determine activation of
caspase-3, as described (35).
In Gel Kinase Assay
[0204] In gel myelin basic protein (MBP) kinase assays were
performed as described previously (38). Either 1000g of total cell
lysates, heart homogenates, or immunoprecipitates of Mst1 were
used. Immunoprecipitation of Mst1 was performed by incubating cell
extracts (300 .quadrature.g) with pAb-15 at 4.degree. C. for 3 h
followed by 40 .quadrature.l slurry (50% v/v) of protein A at
4.degree. C. for 1 h. The samples were washed with the lysis buffer
(700 .quadrature.L) for three times. The immunoprecipitates were
boiled with the Laemmli's SDS-PAGE sample buffer before loading to
SDS-PAGE gel.
Transgenic Mice
[0205] Mst1 and dominant negative Mst1 (DN-Mst1) transgenic mice
(hereafter designated as Tg-Mst1 and Tg-DN-Mst1, respectively) were
generated (C57BL/6 background) using a cDNA of human myc-Mst1 and
myc-Mst1(K59R) driven by the .quadrature.-myosin heavy chain
promoter (courtesy, Dr. J Robbins, University of Cincinnati) to
achieve cardiac specific expression.
Echocardiography
[0206] Mice were anesthetized with an intraperitoneal injection of
ketamine (0.065 mg/g), acepromazine (0.02 mg/g) and xylazine (0.013
mg/g). Echocardiography was performed using ultrasonography (Apogee
CX-200; Interspec Inc., Ambler, Pa.) as described previously (39).
A dynamically focused 9-MHz annular array transducer was applied
from below, using a warmed saline bag as a standoff. M-mode
measurements of LV internal diameter were made from more than 3
beats and averaged. Measurements of end-diastolic diameter (LVEDD)
were taken at the time of the apparent maximal LV diastolic
dimension, while measurements of the LV end-systolic diameter
(LVESD) were taken at the time of the most anterior systolic
excursion of the posterior wall. LV ejection fraction (LVEF) was
calculated by the cubed method as follows:
LVEF=[(LVEDD).sup.3-(LVESD).sup.3]/(LVEDD).sup.3.
Histological Analyses
[0207] The heart specimens were fixed with formalin, embedded in
paraffin, and sectioned at 6 .mu.m thickness. Interstitial fobrosis
was evaluated by picric acid sirius red staining as described (40).
Myocyte cross-sectional area was measured from images captured from
silver-stained 1-.mu.m-thick methacrylate sections as described
(36,39,40). Suitable cross-sections were defined as having nearly
circular capillary profiles and circular-to-oval myocyte sections.
No correction for oblique sectioning was made. The outline of
100-200 myocytes was traced in each section. The MetaMorph image
system software was used to determine myocyte cross-sectional area
(36,39,40). The number of myocyte (N) in the sampled area (A) was
measured according to the criteria described by Gundersen (48)
using Image-Pro Plus software and the myocyte density was
calculated as N/A. Using the histologically determined thickness of
the LV free wall and the myocyte density per unit area of
myocardium, the average number of myocytes across the ventricular
wall was computed as described (49).
Evaluation of Apoptosis in Tissue Sections
[0208] DNA fragmentation was detected in situ by using terminal
deoxyribonucleotide transferase (TdT)-mediated dUTP nick
end-labeling (TUNEL) as described (36,39). Briefly, deparaffinized
sections were incubated with proteinase K and DNA fragments were
labeled with fluorescein-conjugated dUTP using TdT (Roche). Nuclear
density was determined by manual counting of DAPI stained nuclei in
6 fields of each animal using the 40.times. objective, and the
number of TUNEL positive nuclei counted by examining the entire
section using the same power objective. Limiting the counting of
total nuclei and the TUNEL-positive nuclei to areas with true cross
section of myocytes made it possible to selectively count only
those nuclei that clearly were within myocytes (36). For some
samples, triple staining with DAPI, TUNEL, and MF20, and subsequent
analyses using confocal microscopy were performed.
cDNA Expression Array Analyses
[0209] DNA microarray analyses were performed by using Atlas cDNA
expression arrays (Clontech Mouse 1.2 Array-II) according to the
manufacturer's instruction. For each analysis, mRNA was prepared
from two hearts of either Tg-Mst1 or non-transgenic mice. Analyses
of the expression pattern were conducted by using
AtlasNavigator.TM. 2.0 (Clontech). Analyses were repeated three
times, using three different sets of mRNA samples.
Isolation of Adult Mouse Cardiac Myocytes
[0210] Cardiac myocytes were isolated as described previously (41).
Longitudinal length of ventricular cardiac myocytes was determined
as described (41). Whole cell currents were recorded using
patch-clamp techniques (50). Cell capacitance was measured using
voltage ramps of 0.8V/s from a holding potential of -50 mV.
Measurement of Contractile and Relaxation Function
[0211] Cardiac myocytes were isolated as described previously (41).
In brief, the heart was rapidly excised and submerged in
Ca.sup.2+-free Tyrode's solution containing: 140 mmol/L NaCl, 5.4
mmol/L KCl, 1 mmol/L MgCl.sub.2, 0.33 mmol/L
Na.sub.2H.sub.2PO.sub.4, 10 mmol/L glucose, 5 mmol/L HEPES (pH7.4).
The heart was digested using 75 U/mL each of collagenase 1 and 2
(Worthington) at 32.+-.2.degree. C. All solutions were continuously
bubbled with 95% O.sub.2 and 5% CO.sub.2 during digestion.
[0212] Myocyte contraction was induced once per second (1 Hz) and
its function was measured using a video motion edge detector (VED
103, Cresent Electronics) as described previously (41). The
contractile property was determined by % contraction, while the
relaxation property by TL70% (the time for 70% relaxation).
I/R Surgery In Vivo
[0213] Mice were anesthetized by intraperitoneal injection of
pentobarbital sodium (60 mg/kg). A rodent ventilator (model 683,
Harvard Apparatus, Holliston, Mass.) was used with 65% oxygen
during the surgical procedure. Ventilation was provided by passing
a 20-gauge catheter into the trachea. The animals were kept warm by
using heat lamps and heating pads. Rectal temperature was monitored
and maintained between 36.8 and 37.2.degree. C. The chest was
opened by a horizontal incision through the muscle between the ribs
(3rd intercostal space). Ischemia was achieved by ligating the
anterior descending branch of the left coronary artery (LAD) by
using a 8-0 nylon suture, with a silicon tubing (1 mm OD) placed on
top of the LAD, 2 mm below the border between left atrium and left
ventricle. Regional ischemia was confirmed by ECG change (ST
elevation). After occlusion for 20 min, the silicon tubing was
removed to achieve reperfusion. The chest wall was closed by a 8-0
silk. The animal was removed from the ventilator and kept warm in
the cage maintained at 37.degree. C. overnight. Hearts were
harvested after 24 hours of reperfusion.
Assessment of Area at Risk and Infarct Size
[0214] After I/R, the animals were re-anesthetized, intubated and
chest was opened. After arresting the heart at the diastolic phase
by KCl injection, the ascending aorta was canulated and perfused
with saline to wash out blood. The LAD was occluded with the same
suture, which had been left at the site of the ligation. To
demarcate the ischemic area at risk (AAR), Alcian blue dye (1%) was
perfused into the aorta and coronary arteries. Hearts were excised
and LVs were sliced into 1-mm cross sections. The heart sections
were then incubated with a 1% triphenyltetrazolium chloride (TTC)
solution at 37.degree. C. for 10 minutes. Viable myocardium stained
red, and the infarct appeared pale. The infarct area (pale), the
AAR (not blue), and the total LV area from both sides of each
section were measured by using Adobe Photoshop software, and the
values obtained were averaged. The weight of each section was
measured by using a balance (Mettler, Columbus, Ohio). The percent
area of infarction and AAR of each section were multiplied by the
weight of the section and then totaled from all sections. AAR/LV
and infarct area/AAR were calculated and expressed as a percentage.
There was no significant difference in AAR/LV between Tg-DN-Mst1
and non-transgenic littermate control.
Statistics
[0215] All data are reported as mean .+-.SEM. Statistical analyses
between groups were done by one-way (ANOVA), and when F values were
significant at a 95% confidence limit, differences among group
means were evaluated using Fisher's project least significant
difference post-test procedure for group data with a p<0.05
considered significant.
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[0269] This invention may be embodied in other forms or carried out
in other ways without departing from the spirit or essential
characteristics thereof. The present disclosure is therefore to be
considered as in all aspects illustrate and not restrictive, the
scope of the invention being indicated by the appended Claims, and
all changes which come within the meaning and range of equivalency
are intended to be embraced therein.
[0270] Various references are cited throughout this Specification,
each of which is incorporated herein by reference in its entirety.
Sequence CWU 0
0
SEQUENCE LISTING <160> NUMBER OF SEQ ID NOS: 4 <210>
SEQ ID NO 1 <400> SEQUENCE: 1 000 <210> SEQ ID NO 2
<211> LENGTH: 1464 <212> TYPE: DNA <213>
ORGANISM: Homo sapiens <400> SEQUENCE: 2 atggagacgg
tacagctgag gaacccgccg cgccggcagc tgaaaaagtt ggatgaagat 60
agtttaacca aacaaccaga agaagtattt gatgtcttag agaaacttgg agaagggtcc
120 tatggcagcg tatacaaagc tattcataaa gagaccggcc agattgttgc
tattaagcaa 180 gttcctgtgg aatcagacct ccaggagata atcaaagaaa
tctctataat gcagcaatgt 240 gacagccctc atgtagtcaa atattatggc
agttatttta agaacacaga cttatggatc 300 gttatggagt actgtggggc
tggttctgta tctgatatca ttcgattacg aaataaaacg 360 ttaacagaag
atgaaatagc tacaatatta caatcaactc ttaagggact tgaatacctt 420
cattttatga gaaaaataca ccgagatatc aaggcaggaa atattttgct aaatacagaa
480 ggacatgcaa aacttgcaga ttttggggta gcaggtcaac ttacagatac
catggccaag 540 cggaatacag tgataggaac accattttgg atggctccag
aagtgattca ggaaattgga 600 tacaactgtg tagcagacat ctggtccctg
ggaataactg ccatagaaat ggctgaagga 660 aagccccctt atgctgatat
ccatccaatg agggcaatct tcatgattcc tacaaatcct 720 cctcccacat
tccgaaaacc agagctatgg tcagataact ttacagattt tgtgaaacag 780
tgtcttgtaa agagccctga gcagagggcc acagccactc agctcctgca gcacccattt
840 gtcaggagtg ccaaaggagt gtcaatactg cgagacttaa ttaatgaagc
catggatgtg 900 aaactgaaac gccaggaatc ccagcagcgg gaagtggacc
aggacgatga agaaaactca 960 gaagaggatg aaatggattc tggcacgatg
gttcgagcag tgggtgatga gatgggcact 1020 gtccgagtag ccagcaccat
gactgatgga gccaatacta tgattgagca cgatgacacg 1080 ttgccatcac
aactgggcac catggtgatc aatgcagagg atgaggaaga ggaaggaact 1140
atgaaaagaa gggatgagac catgcagcct gcgaaaccat cctttcttga atattttgaa
1200 caaaaagaaa aggaaaacca gatcaacagc tttggcaaga gtgtacctgg
tccactgaaa 1260 aattcttcag attggaaaat accacaggat ggagactacg
agtttcttaa gagttggaca 1320 gtggaggacc ttcagaagag gctcttggcc
ctggacccca tgatggagca ggagattgaa 1380 gagatccggc agaagtacca
gtccaagcgg cagcccatcc tggatgccat agaggctaag 1440 aagagacggc
aacaaaactt ctga 1464 <210> SEQ ID NO 3 <400> SEQUENCE:
3 000 <210> SEQ ID NO 4 <211> LENGTH: 15 <212>
TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE:
4 Glu Thr Val Gln Leu Arg Asn Pro Pro Arg Arg Gln Leu Lys Cys 1 5
10 15
* * * * *