U.S. patent application number 09/841758 was filed with the patent office on 2002-04-11 for novel human selenium-binding protein.
This patent application is currently assigned to Incyte Pharmaceuticals, Inc.. Invention is credited to Bandman, Olga, Hawkins, Phillip R..
Application Number | 20020042066 09/841758 |
Document ID | / |
Family ID | 25015699 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042066 |
Kind Code |
A1 |
Bandman, Olga ; et
al. |
April 11, 2002 |
Novel human selenium-binding protein
Abstract
The present invention provides a human selenium-binding protein
(HSEBP) and polynucleotides which identify and encode HSEBP. The
invention also provides genetically engineered expression vectors
and host cells comprising the nucleic acid sequences encoding HSEBP
and a method for producing HSEBP. The invention also provides for
agonists and antibodies specifically binding HSEBP, and their use
in the prevention and treatment of diseases associated with
expression of HSEBP. Additionally, the invention provides for the
use of antisense molecules to polynucleotides encoding HSEBP for
the treatment of diseases associated with the expression of HSEBP.
The invention also provides diagnostic assays which utilize the
polynucleotide, or fragments or the complement thereof, and
antibodies specifically binding HSEBP.
Inventors: |
Bandman, Olga; (Mountain
View, CA) ; Hawkins, Phillip R.; (Mountain View,
CA) |
Correspondence
Address: |
INCYTE GENOMICS, INC.
PATENT DEPARTMENT
3160 Porter Drive
Palo Alto
CA
94304
US
|
Assignee: |
Incyte Pharmaceuticals,
Inc.
|
Family ID: |
25015699 |
Appl. No.: |
09/841758 |
Filed: |
April 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09841758 |
Apr 24, 2001 |
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09088641 |
Jun 2, 1998 |
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6312895 |
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09088641 |
Jun 2, 1998 |
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08749903 |
Nov 15, 1996 |
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5759812 |
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Current U.S.
Class: |
435/6.14 ;
435/183; 435/7.23; 530/388.26; 536/23.2 |
Current CPC
Class: |
C07K 14/47 20130101;
A61K 38/00 20130101 |
Class at
Publication: |
435/6 ; 435/7.23;
435/183; 530/388.26; 536/23.2 |
International
Class: |
C12Q 001/68; G01N
033/574; C07H 021/04; C12N 009/00; C07K 016/40 |
Claims
What is claimed is:
1. An isolated polypeptide comprising an amino acid sequence
selected from the group consisting of: a) an amino acid sequence of
SEQ ID NO:1, b) a naturally-occurring amino acid sequence having at
least 96% sequence identity to the sequence of SEQ ID NO:1, c) a
biologically-active fragment of the amino acid sequence of SEQ ID
NO:1, and d) an immunogenic fragment of the amino acid sequence of
SEQ ID NO:1.
2. An isolated polypeptide of claim 1, having a sequence of SEQ ID
NO:1.
3. An isolated polynucleotide encoding a polypeptide of claim
1.
4. A recombinant polynucleotide comprising a promoter sequence
operably linked to a polynucleotide of claim 3.
5. A cell transformed with a recombinant polynucleotide of claim
4.
6. A method for producing a polypeptide of claim 1, the method
comprising: a) culturing a cell under conditions suitable for
expression of the polypeptide, wherein said cell is transformed
with a recombinant polynucleotide, and said recombinant
polynucleotide comprises a promoter sequence operably linked to a
polynucleotide encoding the polypeptide of claim 1, and b)
recovering the polypeptide so expressed.
7. An isolated antibody which specifically binds to a polypeptide
of claim 1.
8. An isolated polynucleotide comprising a sequence selected from
the group consisting of: a) a polynucleotide sequence of SEQ ID
NO:2, b) a naturally-occurring polynucleotide sequence having at
least 90% sequence identity to the sequence of SEQ ID NO:2, c) a
polynucleotide sequence complementary to a), d) a polynucleotide
sequence complementary to b) and e) a ribonucleotide equivalent of
a)-d).
9. An isolated polynucleotide comprising at least 60 contiguous
nucleic acids of claim 8.
10. A method for detecting a target polynucleotide in a sample,
said target polynucleotide having a sequence of a polynucleotide of
claim 8, the method comprising: a) hybridizing the sample with a
probe comprising at least 20 contiguous nucleotides comprising a
sequence complementary to said target polynucleotide in the sample,
and which probe specifically hybridizes to said target
polynucleotide, under conditions whereby a hybridization complex is
formed between said probe and said target polynucleotide or
fragments thereof, and b) detecting the presence or absence of said
hybridization complex, and, optionally, if present, the amount
thereof.
11. A method of claim 10, wherein the probe comprises at least 60
contiguous nucleotides.
12. A method for detecting a target polynucleotide in a sample,
said target polynucleotide having a sequence of a polynucleotide of
claim 8, the method comprising: a) amplifying said target
polynucleotide or fragment thereof using polymerase chain reaction
amplification, and b) detecting the presence or absence of said
amplified target polynucleotide or fragment thereof, and,
optionally, if present, the amount thereof.
13. A composition comprising a polypeptide of claim 1 and an
acceptable excipient.
14. A composition of claim 13, wherein the polypeptide has the
sequence of SEQ ID NO:1.
15. A method for screening a compound for effectiveness as an
agonist of a polypeptide of claim 1, the method comprising: a)
exposing a sample comprising a polypeptide of claim 1 to a
compound, and b) detecting agonist activity in the sample.
16. A method for screening a compound for effectiveness as an
antagonist of a polypeptide of claim 1, the method comprising: a)
exposing a sample comprising a polypeptide of claim 1 to a
compound, and b) detecting antagonist activity in the sample.
17. A method for screening a compound for effectiveness in altering
expression of a target polynucleotide, wherein said target
polynucleotide comprises a polynucleotide sequence of claim 8, the
method comprising: a) exposing a sample comprising the target
polynucleotide to a compound, under conditions suitable for the
expression of the target polynucleotide, b) detecting altered
expression of the target polynucleotide, and c) comparing the
expression of the target polynucleotide in the presence of varying
amounts of the compound and in the absence of the compound.
18. A method for assessing toxicity of a test compound, said method
comprising: a) treating a biological sample containing nucleic
acids with the test compound; b) hybridizing the nucleic acids of
the treated biological sample with a probe comprising at least 20
contiguous nucleotides of a polynucleotide of claim 8 under
conditions whereby a specific hybridization complex is formed
between said probe and a target polynucleotide in the biological
sample, said target polynucleotide comprising a polynucleotide
sequence of a polynucleotide of claim 8 or fragment thereof; c)
quantifying the amount of hybridization complex; and d) comparing
the amount of hybridization complex in the treated biological
sample with the amount of hybridization complex in an untreated
biological sample, wherein a difference in the amount of
hybridization complex in the treated biological sample is
indicative of toxicity of the test compound.
19. A diagnostic test for a condition or disease associated with
the expression of HSEBP in a biological sample comprising the steps
of: a) combining the biological sample with an antibody of claim 7,
under conditions suitable for the antibody to bind the polypeptide
and form an antibody: polypeptide complex; and b) detecting the
complex, wherein the presence of the complex correlates with the
presence of the polypeptide in the biological sample.
20. The antibody of claim 7, wherein the antibody is: (a) a
chimeric antibody; (b) a single chain antibody; (c) a Fab fragment;
(d) a F(ab').sub.2 fragment; or (e) a humanized antibody.
21. A composition comprising an antibody of claim 7 and an
acceptable excipient.
22. A method of diagnosing a condition or disease associated with
the expression of HSEBP in a subject, comprising administering to
said subject an effective amount of the composition of claim
21.
23. A composition of claim 21, wherein the antibody is labeled.
24. A method of diagnosing a condition or disease associated with
the expression of HSEBP in a subject, comprising administering to
said subject an effective amount of the composition of claim
23.
25. A method of preparing a polyclonal antibody with the
specificity of the antibody of claim 7 comprising: a) immunizing an
animal with a polypeptide of SEQ ID NO:1 or an immunogenic fragment
thereof under conditions to elicit an antibody response; b)
isolating antibodies from said animal; and c) screening the
isolated antibodies with the polypeptide thereby identifying a
polyclonal antibody which binds specifically to a polypeptide of
SEQ ID NO:1.
26. An antibody produced by a method of claim 25.
27. A composition comprising the antibody of claim 26 and a
suitable carrier.
28. A method of making a monoclonal antibody with the specificity
of the antibody of claim 7 comprising: a) immunizing an animal with
a polypeptide of SEQ ID NO:1 or an immunogenic fragment thereof
under conditions to elicit an antibody response; b) isolating
antibody producing cells from the animal; c) fusing the antibody
producing cells with immortalized cells to form monoclonal
antibody-producing hybridoma cells; d) culturing the hybridoma
cells; and e) isolating from the culture monoclonal antibody which
binds specifically to a polypeptide of SEQ ID NO:1.
29. A monoclonal antibody produced by a method of claim 28.
30. A composition comprising the antibody of claim 29 and a
suitable carrier.
31. The antibody of claim 7, wherein the antibody is produced by
screening a Fab expression library.
32. The antibody of claim 7, wherein the antibody is produced by
screening a recombinant immunoglobulin library.
33. A method for detecting a polypeptide of SEQ ID NO:1 in a sample
comprising the steps of: a) incubating the antibody of claim 7 with
a sample under conditions to allow specific binding of the antibody
and the polypeptide; and b) detecting specific binding, wherein
specific binding indicates the presence of a polypeptide of SEQ ID
NO:1 in the sample.
34. A method of purifying a polypeptide of SEQ ID NO:1 from a
sample, the method comprising: a) incubating the antibody of claim
7 with a sample under conditions to allow specific binding of the
antibody and the polypeptide; and b) separating the antibody from
the sample and obtaining purified polypeptide of SEQ ID NO:1.
Description
[0001] This application is a divisional application of U.S.
application Ser. No. 09/088,641, filed Jun. 2, 1998, which is
itself a divisional application of U.S. application Ser. No.
08/749,903, filed Nov. 15, 1996, issued as U.S. Pat. No. 5,759,812
on Jun. 2, 1998, both entitled NOVEL HUMAN SELENIUM-BINDING
PROTEIN, all of which applications and patents are hereby
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to nucleic acid and amino acid
sequences of a novel human selenium-binding protein and to the use
of these sequences in the diagnosis, prevention, and treatment of
chemically-induced tissue damage, carcinogenesis, and cancer.
BACKGROUND OF THE INVENTION
[0003] The biological activity of selenium (Se) has been studied
for over 40 years, but its precise function has not been fully
elucidated. Originally identified as a highly toxic substance when
ingested in large amounts, Se, usually in the form of disodium
selenite (Na.sub.2SeO.sub.3), is now recognized as an essential
trace element in eukaryotes and as a potent anticarcinogenic agent
in a variety of animal models (Medina, D. and D. G. Morrison (1988)
Pathol. Immunopathol. Res. 7:187-199; Lane, H. W. et al. (1989) In
Vivo 3:151-160; Ip, C. (1986) J. Am. Coll. Toxicol. 5:7-20; Medina
D. (1986) J. Am. Coll. Toxicol. 5:7-20; Combs, G. F. and S. B.
Combs (1986) in The Role of Selenium in Nutrition, Academic Press,
San Diego, Calif.; pp. 413-461). Dietary Se affords protection
against both the initiation and promotion of carcinogenesis, and
there is increasing epidemiological evidence to support its
anticarcinogenic role in humans (Knekt, P. et al. (1990) J. Natl.
Cancer. Inst. 82:864-868).
[0004] Se-containing proteins are detected in a broad spectrum of
tissues in vivo and in cell lines in vitro by labeling with trace
amounts of radioactive .sup.75Se (see for example, Morrison, D. G.
et al. (1988) Anticancer Res. 8:51-64; Pederson, N. D. et al.
(1972) Bioinorg. Chem. 2:33-45; Calvin, H. I. (1978) J. Exp. Zool.
204: 445-452; Motsenbocker, M. A. and A. L. Tappel (1982) Biochim.
Biophys. Acta 709:160-165). Se is incorporated directly into
proteins such as glutathione peroxidase, type I iodothyronine
deiodinase, and selenoprotein P during translation. Incorporation
of Se into these proteins is via the modified amino acid
selenocysteine that is inserted into the nascent polypeptide in
response to an in-frame UGA termination codon (Chambers, I. et al.
(1986) EMBO J. 5:1221-1227; Takahashi, K. et al. (1990) J. Biochem.
(Tokyo) 108:145-148; Berry, M. J. (1991) Nature 349:438-440; Hill,
K. E. (1991) J. Biol. Chem. 266:10050-10053).
[0005] Some proteins do not contain selenocysteine but bind Se
non-covalently. The precise nature of the binding site has not been
established, but probably requires a pair of cysteine residues
(Handel, M. L. et al. (1995) Proc. Natl. Acad. Sci. 92:4497-4501)
because selenite is a potent oxidant of thiols. Additional
structural elements must also play an important role in binding
because only a limited number of .sup.75Se-labeled proteins can be
detected by SDS-polyacrylamide gel electrophoresis after labeling
in vivo.
[0006] Several Se-binding proteins from mouse, rat, and human have
been identified and characterized (Bansal M. P. et al. (1990)
Carcinogenesis 11:2071-2073; Bartolone, J. B. et al. (1992)
Toxicol. Appl. Pharmacol. 113:19-29; Lanfear, J. et al. (1993)
Carcinogenesis 14:335-340; Handel, M. L. et al., supra; Ishii, Y.
et al. (1996) Toxicol Lett. 87:1-9; Spyrou, G. (1995) FEBS Lett.
368:59-63; Chang, P. W. G. et al., unpublished). Some of them
belong to a family of highly homologous cytosolic proteins with
similar molecular weights (ca. 54-58 kDa) and overlapping tissue
distributions in the kidney, liver, lung, gastrointestinal tract,
and male and female endocrine glands.
[0007] At least two related, but separately regulated genes, for
Se-binding proteins are present in the mouse (Lanfear, J. et al.,
supra). One of these encodes the previously described .about.58-kDa
acetaminophen-binding protein (58-ABP). 58-ABP is thought to be a
target for arylation by the widely used analgesic acetaminophen and
its metabolites following acute drug overdose. Arylation can lead
to life-threatening liver necrosis and to kidney and lung
damage.
[0008] Se-binding proteins have been implicated in cellular growth
control and the protection from carcinogenesis and cancer. For
example, Morrison, D. G. et al. (1988; Carcinogenesis 9:1801-1810)
have correlated the inhibition of DNA synthesis with the level of
Se bound to proteins in mouse mammary epithelial cells in culture.
Higher levels of bound Se are observed in non-growing cells than in
growing cells, but the level of protein is unaffected. This
suggests that Se binding modifies the activity of pre-existing
proteins. Ishii, Y. et al. (supra) have also demonstrated that
synthesis of an Se-binding protein is induced in rats treated with
a known disease-causing polychlorinated biphenyl (PCB)
compound.
[0009] Although not structurally related to the 54-58-kDa family of
Se-binding proteins, the Fos and Jun subunits of the AP-1
transcription factor also bind Se and are thereby unable to bind to
their DNA recognition sequence. As a consequence, transcription
from AP-1-dependent promoters is inhibited by the addition of
selenite to the culture media, whereas transcription from
AP-2-dependent promoters is unaffected (Handel, M. et al., supra;
Spyrou, G. et al., supra). The inhibition of transcription may thus
provide an explanation for some of selenium's observed biological
activities.
[0010] The discovery of polynucleotides encoding the
selenium-binding protein, and the molecules themselves, provides
the means to investigate the regulation of DNA synthesis and
transcription by inorganic ions. Discovery of molecules related to
the selenium-binding protein satisfies a need in the art by
providing new diagnostic or therapeutic compositions useful in the
diagnosis, prevention, and treatment of conditions and diseases
associated with the activity of selenium-binding proteins such as
liver necrosis and kidney or lung damage resulting from
acetaminophen toxicity, as well as liver, kidney, lung, mammary,
epithelial, gastrointestinal, and endocrine cancer.
SUMMARY OF THE INVENTION
[0011] The present invention features a novel human
selenium-binding protein hereinafter designated HSEBP and
characterized as having chemical and structural homology to
selenium-binding proteins of fetal human heart, mouse, and rat.
Accordingly, the invention features a substantially purified HSEBP
having the amino acid sequence, SEQ ID NO:1.
[0012] One aspect of the invention features isolated and
substantially purified polynucleotides that encode HSEBP. In a
particular aspect, the polynucleotide is the nucleotide sequence of
SEQ ID NO:2.
[0013] The invention also relates to a polynucleotide sequence
comprising the complement of SEQ ID NO:2 or variants thereof. In
addition, the invention features polynucleotide sequences which
hybridize under stringent conditions to SEQ ID NO:2.
[0014] The invention additionally features nucleic acid sequences
encoding polypeptides, oligonucleotides, peptide nucleic acids
(PNA), fragments, portions or antisense molecules thereof, and
expression vectors and host cells comprising polynucleotides that
encode HSEBP. The present invention also features antibodies which
bind specifically to HSEBP, and pharmaceutical compositions
comprising substantially purified HSEBP. The invention also
features the use of agonists and antagonists of HSEBP.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIGS. 1A, 1B, 1C, 1D, and 1E show the amino acid sequence
(SEQ ID NO:1) and nucleic acid sequence (SEQ ID NO:2) of HSEBP. The
alignment was produced using MacDNASIS PRO.TM. software (Hitachi
Software Engineering Co., Ltd., San Bruno, Calif.).
[0016] FIGS. 2A, 2B, and 2C show the amino acid sequence alignments
among HSEBP (SEQ ID NO:1), human fetal heart Se-binding protein
(G1374792; SEQ ID NO:3), mouse liver Se-binding protein (G227630;
SEQ ID NO:4), and mouse liver acetaminophen-binding protein
(G298710; SEQ ID NO:5). The alignment was produced using the
multisequence alignment program of DNASTAR.TM. software (DNASTAR
Inc, Madison Wis.).
[0017] FIG. 3 shows the hydrophobicity plot (MacDNASIS PRO
software) for HSEBP, SEQ ID NO:1; the positive X axis reflects
amino acid position, and the negative Y axis, hydrophobicity.
[0018] FIG. 4 shows the hydrophobicity plot for G1374792, SEQ ID
NO:4.
[0019] FIG. 5 shows the northern analysis for SEQ ID NO:2. The
northern analysis was produced electronically using LIFESEQ FL.TM.
database (Incyte Pharmaceuticals, Inc., Palo Alto, Calif.).
DESCRIPTION OF THE INVENTION
[0020] Before the present proteins, nucleotide sequences, and
methods are described, it is understood that this invention is not
limited to the particular methodology, protocols, cell lines,
vectors, and reagents described as these may vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to
limit the scope of the present invention which will be limited only
by the appended claims.
[0021] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
reference unless the context clearly dictates otherwise. Thus, for
example, reference to "a host cell" includes a plurality of such
host cells, reference to the "antibody" is a reference to one or
more antibodies and equivalents thereof known to those skilled in
the art, and so forth.
[0022] Unless defined otherwise, all technical and scientific terms
used herein have the same meanings as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods, devices, and materials are now
described. All publications mentioned herein are incorporated
herein by reference for the purpose of describing and disclosing
the cell lines, vectors, and methodologies which are reported in
the publications which might be used in connection with the
invention. Nothing herein is to be construed as an admission that
the invention is not entitled to antedate such disclosure by virtue
of prior invention.
[0023] Definitions
[0024] "Nucleic acid sequence" as used herein refers to an
oligonucleotide, nucleotide, or polynucleotide, and fragments or
portions thereof, and to DNA or RNA of genomic or synthetic origin
which may be single- or double-stranded, and represents the sense
or antisense strand. Similarly, "amino acid sequence" as used
herein refers to an oligopeptide, peptide, polypeptide, or protein
sequence, and fragments or portions thereof, and to naturally
occurring or synthetic molecules.
[0025] Where "amino acid sequence" is recited herein to refer to an
amino acid sequence of a naturally occurring protein molecule,
"amino acid sequence" and like terms, such as "polypeptide" or
"protein" are not meant to limit the amino acid sequence to the
complete, native amino acid sequence associated with the recited
protein molecule.
[0026] "Peptide nucleic acid", as used herein, refers to a molecule
which comprises an oligomer to which an amino acid residue, such as
lysine, and an amino group have been added. These small molecules,
also designated anti-gene agents, stop transcript elongation by
binding to their complementary strand of nucleic acid (Nielsen, P.
E. et al. (1993) Anticancer Drug Des. 8:53-63).
[0027] HSEBP, as used herein, refers to the amino acid sequences of
substantially purified HSEBP obtained from any species,
particularly mammalian, including bovine, ovine, porcine, murine,
equine, and preferably human, from any source whether natural,
synthetic, semi-synthetic, or recombinant.
[0028] "Consensus", as used herein, refers to a nucleic acid
sequence which has been resequenced to resolve uncalled bases, or
which has been extended using XL-PCR.TM. (Perkin Elmer, Norwalk,
Conn.) in the 5' and/or the 3' direction and resequenced, or which
has been assembled from the overlapping sequences of more than one
Incyte clone using the GELVIEW.TM. Fragment Assembly system (GCG,
Madison, Wis.), or which has been both extended and assembled.
[0029] A "variant" of HSEBP, as used herein, refers to an amino
acid sequence that is altered by one or more amino acids. The
variant may have "conservative" changes, wherein a substituted
amino acid has similar structural or chemical properties, e.g.,
replacement of leucine with isoleucine. More rarely, a variant may
have "nonconservative" changes, e.g., replacement of a glycine with
a tryptophan. Similar minor variations may also include amino acid
deletions or insertions, or both. Guidance in determining which
amino acid residues may be substituted, inserted, or deleted
without abolishing biological or immunological activity may be
found using computer programs well known in the art, for example,
DNASTAR software.
[0030] A "deletion", as used herein, refers to a change in either
amino acid or nucleotide sequence in which one or more amino acid
or nucleotide residues, respectively, are absent.
[0031] An "insertion" or "addition", as used herein, refers to a
change in an amino acid or nucleotide sequence resulting in the
addition of one or more amino acid or nucleotide residues,
respectively, as compared to the naturally occurring molecule.
[0032] A "substitution", as used herein, refers to the replacement
of one or more amino acids or nucleotides by different amino acids
or nucleotides, respectively.
[0033] The term "biologically active", as used herein, refers to a
protein having structural, regulatory, or biochemical functions of
a naturally occurring molecule. Likewise, "immunologically active"
refers to the capability of the natural, recombinant, or synthetic
HSEBP, or any oligopeptide thereof, to induce a specific immune
response in appropriate animals or cells and to bind with specific
antibodies.
[0034] The term "agonist", as used herein, refers to a molecule
which, when bound to HSEBP, causes a change in HSEBP which
modulates the activity of HSEBP. Agonists may include proteins,
nucleic acids, carbohydrates, or any other molecules which bind to
HSEBP.
[0035] The terms "antagonist" or "inhibitor", as used herein, refer
to a molecule which, when bound to HSEBP, modulates or blocks the
biological or immunological activity of HSEBP. Antagonists and
inhibitors may include proteins, nucleic acids, carbohydrates, or
any other molecules which bind to HSEBP.
[0036] The term "modulate", as used herein, refers to a change or
an alteration in the biological activity of HSEBP. Modulation may
be an increase or a decrease in protein activity, a change in
binding characteristics, or any other change in the biological,
functional or immunological properties of HSEBP.
[0037] The term "mimetic", as used herein, refers to a molecule,
the structure of which is developed from knowledge of the structure
of HSEBP or portions thereof and, as such, is able to effect some
or all of the actions of selenium-binding-like molecules.
[0038] The term "derivative", as used herein, refers to the
chemical modification of a nucleic acid encoding HSEBP or the
encoded HSEBP. Illustrative of such modifications would be
replacement of hydrogen by an alkyl, acyl, or amino group. A
nucleic acid derivative would encode a polypeptide which retains
essential biological characteristics of the natural molecule.
[0039] The term "substantially purified", as used herein, refers to
nucleic or amino acid sequences that are removed from their natural
environment, isolated or separated, and are at least 60% free,
preferably 75% free, and most preferably 90% free from other
components with which they are naturally associated.
[0040] "Amplification" as used herein refers to the production of
additional copies of a nucleic acid sequence and is generally
carried out using polymerase chain reaction (PCR) technologies well
known in the art (Dieffenbach, C. W. and G. S. Dveksler (1995) PCR
Primer, a Laboratory Manual, Cold Spring Harbor Press, Plainview,
N.Y.).
[0041] The term "hybridization", as used herein, refers to any
process by which a strand of nucleic acid binds with a
complementary strand through base pairing.
[0042] The term "hybridization complex", as used herein, refers to
a complex formed between two nucleic acid sequences by virtue of
the formation of hydrogen bonds between complementary G and C bases
and between complementary A and T bases; these hydrogen bonds may
be further stabilized by base stacking interactions. The two
complementary nucleic acid sequences hydrogen bond in an
antiparallel configuration. A hybridization complex may be formed
in solution (e.g., C.sub.0t or R.sub.0t analysis) or between one
nucleic acid sequence present in solution and another nucleic acid
sequence immobilized on a solid support (e.g., membranes, filters,
chips, pins or glass slides to which cells have been fixed for in
situ hybridization).
[0043] The terms "complementary" or "complementarity", as used
herein, refer to the natural binding of polynucleotides under
permissive salt and temperature conditions by base-pairing. For
example, the sequence "A-G-T" binds to the complementary sequence
"T-C-A". Complementarity between two single-stranded molecules may
be "partial", in which only some of the nucleic acids bind, or it
may be complete when total complementarity exists between the
single stranded molecules. The degree of complementarity between
nucleic acid strands has significant effects on the efficiency and
strength of hybridization between nucleic acid strands. This is of
particular importance in amplification reactions, which depend upon
binding between nucleic acids strands.
[0044] The term "homology", as used herein, refers to a degree of
complementarity. There may be partial homology or complete homology
(i.e., identity). A partially complementary sequence is one that at
least partially inhibits an identical sequence from hybridizing to
a target nucleic acid; it is referred to using the functional term
"substantially homologous." The inhibition of hybridization of the
completely complementary sequence to the target sequence may be
examined using a hybridization assay (Southern or northern blot,
solution hybridization and the like) under conditions of low
stringency. A substantially homologous sequence or probe will
compete for and inhibit the binding (i.e., the hybridization) of a
completely homologous sequence or probe to the target sequence
under conditions of low stringency. This is not to say that
conditions of low stringency are such that non-specific binding is
permitted; low stringency conditions require that the binding of
two sequences to one another be a specific (i.e., selective)
interaction. The absence of non-specific binding may be tested by
the use of a second target sequence which lacks even a partial
degree of complementarity (e.g., less than about 30% identity); in
the absence of non-specific binding, the probe will not hybridize
to the second non-complementary target sequence.
[0045] As known in the art, numerous equivalent conditions may be
employed to comprise either low or high stringency conditions.
Factors such as the length and nature (DNA, RNA, base composition)
of the sequence, nature of the target (DNA, RNA, base composition,
presence in solution or immobilization, etc.), and the
concentration of the salts and other components (e.g., the presence
or absence of formamide, dextran sulfate and/or polyethylene
glycol) are considered and the hybridization solution may be varied
to generate conditions of either low or high stringency different
from, but equivalent to, the above listed conditions.
[0046] The term "stringent conditions", as used herein, is the
"stringency" which occurs within a range from about Tm-5.degree. C.
(5.degree. C. below the melting temperature (Tm) of the probe) to
about 20.degree. C to 25.degree. C. below Tm. As will be understood
by those of skill in the art, the stringency of hybridization may
be altered in order to identify or detect identical or related
polynucleotide sequences.
[0047] The term "antisense", as used herein, refers to nucleotide
sequences which are complementary to a specific DNA or RNA
sequence. The term "antisense strand" is used in reference to a
nucleic acid strand that is complementary to the "sense" strand.
Antisense molecules may be produced by any method, including
synthesis by ligating the gene(s) of interest in a reverse
orientation to a viral promoter which permits the synthesis of a
complementary strand. Once introduced into a cell, this transcribed
strand combines with natural sequences produced by the cell to form
duplexes. These duplexes then block either the further
transcription or translation. In this manner, mutant phenotypes may
be generated. The designation "negative" is sometimes used in
reference to the antisense strand, and "positive" is sometimes used
in reference to the sense strand.
[0048] The term "portion", as used herein, with regard to a protein
(as in "a portion of a given protein") refers to fragments of that
protein. The fragments may range in size from four amino acid
residues to the entire amino acid sequence minus one amino acid.
Thus, a protein "comprising at least a portion of the amino acid
sequence of SEQ ID NO:1" encompasses the full-length human HSEBP
and fragments thereof.
[0049] "Transformation", as defined herein, describes a process by
which exogenous DNA enters and changes a recipient cell. It may
occur under natural or artificial conditions using various methods
well known in the art. Transformation may rely on any known method
for the insertion of foreign nucleic acid sequences into a
prokaryotic or eukaryotic host cell. The method is selected based
on the host cell being transformed and may include, but is not
limited to, viral infection, electroporation, lipofection, and
particle bombardment. Such "transformed" cells include stably
transformed cells in which the inserted DNA is capable of
replication either as an autonomously replicating plasmid or as
part of the host chromosome. They also include cells which
transiently express the inserted DNA or RNA for limited periods of
time.
[0050] The term "antigenic determinant", as used herein, refers to
that portion of a molecule that makes contact with a particular
antibody (i.e., an epitope). When a protein or fragment of a
protein is used to immunize a host animal, numerous regions of the
protein may induce the production of antibodies which bind
specifically to a given region or three-dimensional structure on
the protein; these regions or structures are referred to as
antigenic determinants. An antigenic determinant may compete with
the intact antigen (i.e., the immunogen used to elicit the immune
response) for binding to an antibody.
[0051] The terms "specific binding" or "specifically binding", as
used herein, in reference to the interaction of an antibody and a
protein or peptide, mean that the interaction is dependent upon the
presence of a particular structure (i.e., the antigenic determinant
or epitope) on the protein; in other words, the antibody is
recognizing and binding to a specific protein structure rather than
to proteins in general. For example, if an antibody is specific for
epitope "A", the presence of a protein containing epitope A (or
free, unlabeled A) in a reaction containing labeled "A" and the
antibody will reduce the amount of labeled A bound to the
antibody.
[0052] The term "sample", as used herein, is used in its broadest
sense. A biological sample suspected of containing nucleic acid
encoding HSEBP or fragments thereof may comprise a cell,
chromosomes isolated from a cell (e.g., a spread of metaphase
chromosomes), genomic DNA (in solution or bound to a solid support
such as for Southern analysis), RNA (in solution or bound to a
solid support such as for northern analysis), cDNA (in solution or
bound to a solid support), an extract from cells or a tissue, and
the like.
[0053] The term "correlates with expression of a polynucleotide",
as used herein, indicates that the detection of the presence of
ribonucleic acid that is similar to SEQ ID NO:2 by northern
analysis is indicative of the presence of mRNA encoding HSEBP in a
sample and thereby correlates with expression of the transcript
from the polynucleotide encoding the protein.
[0054] "Alterations" in the polynucleotide of SEQ ID NO:2, as used
herein, comprise any alteration in the sequence of polynucleotides
encoding HSEBP including deletions, insertions, and point mutations
that may be detected using hybridization assays. Included within
this definition is the detection of alterations to the genomic DNA
sequence which encodes HSEBP (e.g., by alterations in the pattern
of restriction fragment length polymorphisms capable of hybridizing
to SEQ ID NO:2), the inability of a selected fragment of SEQ ID
NO:2 to hybridize to a sample of genomic DNA (e.g., using
allele-specific oligonucleotide probes), and improper or unexpected
hybridization, such as hybridization to a locus other than the
normal chromosomal locus for the polynucleotide sequence encoding
HSEBP (e.g., using fluorescent in situ hybridization [FISH] to
metaphase chromosome spreads).
[0055] As used herein, the term "antibody" refers to intact
molecules as well as fragments thereof, such as Fa, F(ab').sub.2,
and Fv, which are capable of binding the epitopic determinant.
Antibodies that bind HSEBP polypeptides can be prepared using
intact polypeptides or fragments containing small peptides of
interest as the immunizing antigen. The polypeptide or peptide used
to immunize an animal can be derived from the transition of RNA or
synthesized chemically, and can be conjugated to a carrier protein,
if desired. Commonly used carriers that are chemically coupled to
peptides include bovine serum albumin and thyroglobulin. The
coupled peptide is then used to immunize the animal (e.g., a mouse,
a rat, or a rabbit).
[0056] The term "humanized antibody", as used herein, refers to
antibody molecules in which amino acids have been replaced in the
non-antigen binding regions in order to more closely resemble a
human antibody, while still retaining the original binding
ability.
[0057] The Invention
[0058] The invention is based on the discovery of a novel human
selenium-binding protein (HSEBP), the polynucleotides encoding
HSEBP, and the use of these compositions for the diagnosis,
prevention or treatment of conditions and diseases such as liver
necrosis, and kidney or lung damage resulting from chemical
toxicity, as well as liver, kidney, lung, mammary, epithelial,
gastrointestinal, and endocrine cancer.
[0059] Nucleic acids encoding the HSEBP of the present invention
were first identified in Incyte Clone 989953 from the colon cDNA
library (COLNNOT11) through a computer-generated search for amino
acid sequence alignments. A consensus sequence, SEQ ID NO:2, was
derived from the following overlapping and/or extended nucleic acid
sequences: Incyte Clones 989953 (COLNNOT11), 609011, 1226183, and
1227155 (COLNNOT01), 1334268 (COLNNOT13), 1284686 (COLNNOT16),
1391936 (THYRNOT03), (COLNNOT01), 959734 (BRSTTUT03, 892480
(STOMTUT01), and 814959 (OVARTUT01).
[0060] In one embodiment, the invention encompasses the novel human
selenium-binding protein, a polypeptide comprising the amino acid
sequence of SEQ ID NO:1, as shown in FIGS. 1A, B, C. HSEBP is 472
amino acids in length and has no predicted transmembrane domains,
potential glycosylation or phosphorylation sites. HSEBP is enriched
in leucine and glycine residues which together constitute more than
20% of the total amino acid content. As shown in FIGS. 1A, B, C,
there are no in-frame TGA termination codons in the nucleic acid
sequence of SEQ ID NO:2 to direct the incorporation of
selenocysteine into the protein of SEQ ID NO:1. HSEBP has chemical
and structural homology with the human fetal heart selenium-binding
protein (G1374972; SEQ ID NO:3), mouse liver selenium-binding
protein (G227630; SEQ ID NO:4), and mouse liver
acetaminophen-binding protein (G298710; SEQ ID NO:5). In
particular, HSEBP shares 96%, 86%, and 88% identity, respectively,
with each of these proteins. As illustrated by FIGS. 3 and 4, HSEBP
and human fetal heart selenium-binding protein have rather similar
hydrophobicity plots. Their isoelectric points, 5.91 and 6.13,
respectively, are also similar. Northern analysis (FIG. 5) shows
the expression of the HSEBP sequence in various libraries.
Approximately 50% of these libraries are from cancerous tissues and
38% are from the gastrointestinal tract.
[0061] The invention also encompasses HSEBP variants. A preferred
HSEBP variant is one having at least 80%, and more preferably 90%,
amino acid sequence similarity to the HSEBP amino acid sequence
(SEQ ID NO:1). A most preferred HSEBP variant is one having at
least 95% amino acid sequence similarity to SEQ ID NO:1.
[0062] The invention also encompasses polynucleotides which encode
HSEBP. Accordingly, any nucleic acid sequence which encodes the
amino acid sequence of HSEBP can be used to generate recombinant
molecules which express HSEBP. In a particular embodiment, the
invention encompasses the polynucleotide comprising the nucleic
acid sequence of SEQ ID NO:2 as shown in FIGS. lA, B, C.
[0063] It will be appreciated by those skilled in the art that as a
result of the degeneracy of the genetic code, a multitude of
nucleotide sequences encoding HSEBP, some bearing minimal homology
to the nucleotide sequences of any known and naturally occurring
gene, may be produced. Thus, the invention contemplates each and
every possible variation of nucleotide sequence that could be made
by selecting combinations based on possible codon choices. These
combinations are made in accordance with the standard triplet
genetic code as applied to the nucleotide sequence of naturally
occurring HSEBP, and all such variations are to be considered as
being specifically disclosed.
[0064] Although nucleotide sequences which encode HSEBP and its
variants are preferably capable of hybridizing to the nucleotide
sequence of the naturally occurring HSEBP under appropriately
selected conditions of stringency, it may be advantageous to
produce nucleotide sequences encoding HSEBP or its derivatives
possessing a substantially different codon usage. Codons may be
selected to increase the rate at which expression of the peptide
occurs in a particular prokaryotic or eukaryotic host in accordance
with the frequency with which particular codons are utilized by the
host. Other reasons for substantially altering the nucleotide
sequence encoding HSEBP and its derivatives without altering the
encoded amino acid sequences include the production of RNA
transcripts having more desirable properties, such as a greater
half-life, than transcripts produced from the naturally occurring
sequence.
[0065] The invention also encompasses production of DNA sequences,
or portions thereof, which encode HSEBP and its derivatives,
entirely by synthetic chemistry. After production, the synthetic
sequence may be inserted into any of the many available expression
vectors and cell systems using reagents that are well known in the
art at the time of the filing of this application. Moreover,
synthetic chemistry may be used to introduce mutations into a
sequence encoding HSEBP or any portion thereof.
[0066] Also encompassed by the invention are polynucleotide
sequences that are capable of hybridizing to the claimed nucleotide
sequences, and in particular, those shown in SEQ ID NO:2, under
various conditions of stringency. Hybridization conditions are
based on the melting temperature (Tm) of the nucleic acid binding
complex or probe, as taught in Wahl, G. M. and S. L. Berger (1987;
Methods Enzymol. 152:399-407) and Kimmel, A. R. (1987; Methods
Enzymol. 152:507-511), and may be used at a defined stringency.
[0067] Altered nucleic acid sequences encoding HSEBP which are
encompassed by the invention include deletions, insertions, or
substitutions of different nucleotides resulting in a
polynucleotide that encodes the same or a functionally equivalent
HSEBP. The encoded protein may also contain deletions, insertions,
or substitutions of amino acid residues which produce a silent
change and result in a functionally equivalent HSEBP. Deliberate
amino acid substitutions may be made on the basis of similarity in
polarity, charge, solubility, hydrophobicity, hydrophilicity,
and/or the amphipathic nature of the residues as long as the
biological activity of HSEBP is retained. For example, negatively
charged amino acids may include aspartic acid and glutamic acid;
positively charged amino acids may include lysine and arginine; and
amino acids with uncharged polar head groups having similar
hydrophilicity values may include leucine, isoleucine, and valine;
glycine and alanine; asparagine and glutamine; serine and
threonine; and phenylalanine and tyrosine.
[0068] Also included within the scope of the present invention are
alleles of the genes encoding HSEBP. As used herein, an "allele" or
"allelic sequence" is an alternative form of the gene which may
result from at least one mutation in the nucleic acid sequence.
Alleles may result in altered mRNAs or polypeptides whose structure
or function may or may not be altered. Any given gene may have
none, one, or many allelic forms. Common mutational changes which
give rise to alleles are generally ascribed to natural deletions,
additions, or substitutions of nucleotides. Each of these types of
changes may occur alone, or in combination with the others, one or
more times in a given sequence.
[0069] Methods for DNA sequencing which are well known and
generally available in the art may be used to practice any
embodiments of the invention. The methods may employ such enzymes
as the Klenow fragment of DNA polymerase I, Sequenase.RTM. (US
Biochemical Corp, Cleveland, Ohio), Taq polymerase (Perkin Elmer),
thermostable T7 polymerase (Amersham, Chicago, Ill.), or
combinations of recombinant polymerases and proofreading
exonucleases such as the ELONGASE Amplification System marketed by
Gibco BRL (Gaithersburg, Md.). Preferably, the process is automated
with machines such as the Hamilton Micro Lab 2200 (Hamilton, Reno,
Nev.), Peltier Thermal Cycler (PTC200; MJ Research, Watertown,
Mass.) and the ABI 377 DNA sequencers (Perkin Elmer).
[0070] The nucleic acid sequences encoding HSEBP may be extended
utilizing a partial nucleotide sequence and employing various
methods known in the art to detect upstream sequences such as
promoters and regulatory elements. For example, one method which
may be employed, "restriction-site" PCR, uses universal primers to
retrieve unknown sequence adjacent to a known locus (Sarkar, G.
(1993) PCR Methods Applic. 2:318-322). In particular, genomic DNA
is first amplified in the presence of primer to linker sequence and
a primer specific to the known region. The amplified sequences are
then subjected to a second round of PCR with the same linker primer
and another specific primer internal to the first one. Products of
each round of PCR are transcribed with an appropriate RNA
polymerase and sequenced using reverse transcriptase.
[0071] Inverse PCR may also be used to amplify or extend sequences
using divergent primers based on a known region (Triglia, T. et al.
(1988) Nucleic Acids Res. 16:8186). The primers may be designed
using OLIGO 4.06 Primer Analysis software (National Biosciences
Inc., Plymouth, Minn.), or another appropriate program, to be 22-30
nucleotides in length, to have a GC content of 50% or more, and to
anneal to the target sequence at temperatures about
68.degree.-72.degree. C. The method uses several restriction
enzymes to generate a suitable fragment in the known region of a
gene. The fragment is then circularized by intramolecular ligation
and used as a PCR template.
[0072] Another method which may be used is capture PCR which
involves PCR amplification of DNA fragments adjacent to a known
sequence in human and yeast artificial chromosome DNA (Lagerstrom,
M. et al. (1991) PCR Methods Applic. 1:111-119). In this method,
multiple restriction enzyme digestions and ligations may also be
used to place an engineered double-stranded sequence into an
unknown portion of the DNA molecule before performing PCR.
[0073] Another method which may be used to retrieve unknown
sequences is that of Parker, J. D. et al. (1991; Nucleic Acids Res.
19:3055-3060). Additionally, one may use PCR, nested primers, and
PromoterFinder.TM. libraries to walk in genomic DNA (Clontech, Palo
Alto, Calif.). This process avoids the need to screen libraries and
is useful in finding intron/exon junctions.
[0074] When screening for full-length cDNAs, it is preferable to
use libraries that have been size-selected to include larger cDNAs.
Also, random-primed libraries are preferable, in that they will
contain more sequences which contain the 5' regions of genes. Use
of a randomly primed library may be especially preferable for
situations in which an oligo d(T) library does not yield a
full-length cDNA. Genomic libraries may be useful for extension of
sequence into the 5' and 3' non-transcribed regulatory regions.
[0075] Capillary electrophoresis systems which are commercially
available may be used to analyze the size or confirm the nucleotide
sequence of sequencing or PCR products. In particular, capillary
sequencing may employ flowable polymers for electrophoretic
separation, four different fluorescent dyes (one for each
nucleotide) which are laser activated, and detection of the emitted
wavelengths by a charge coupled device camera. Output/light
intensity may be converted to electrical signal using appropriate
software (e.g. Genotyper.TM. and Sequence Navigator.TM., Perkin
Elmer) and the entire process from loading of samples to computer
analysis and electronic data display may be computer controlled.
Capillary electrophoresis is especially preferable for the
sequencing of small pieces of DNA which might be present in limited
amounts in a particular sample.
[0076] In another embodiment of the invention, polynucleotide
sequences or fragments thereof which encode HSEBP, or fusion
proteins or functional equivalents thereof, may be used in
recombinant DNA molecules to direct expression of HSEBP in
appropriate host cells. Due to the inherent degeneracy of the
genetic code, other DNA sequences which encode substantially the
same or a functionally equivalent amino acid sequence may be
produced and these sequences may be used to clone and express
HSEBP.
[0077] As will be understood by those of skill in the art, it may
be advantageous to produce HSEBP-encoding nucleotide sequences
possessing non-naturally occurring codons. For example, codons
preferred by a particular prokaryotic or eukaryotic host can be
selected to increase the rate of protein expression or to produce a
recombinant RNA transcript having desirable properties, such as a
half-life which is longer than that of a transcript generated from
the naturally occurring sequence.
[0078] The nucleotide sequences of the present invention can be
engineered using methods generally known in the art in order to
alter HSEBP encoding sequences for a variety of reasons, including
but not limited to, alterations which modify the cloning,
processing, and/or expression of the gene product. DNA shuffling by
random fragmentation and PCR reassembly of gene fragments and
synthetic oligonucleotides may be used to engineer the nucleotide
sequences. For example, site-directed mutagenesis may be used to
insert new restriction sites, alter glycosylation patterns, change
codon preference, produce splice variants, or introduce mutations,
and so forth.
[0079] In another embodiment of the invention, natural, modified,
or recombinant nucleic acid sequences encoding HSEBP may be ligated
to a heterologous sequence to encode a fusion protein. For example,
to screen peptide libraries for inhibitors of HSEBP activity, it
may be useful to encode a chimeric HSEBP protein that can be
recognized by a commercially available antibody. A fusion protein
may also be engineered to contain a cleavage site located between
the HSEBP encoding sequence and the heterologous protein sequence,
so that HSEBP may be cleaved and purified away from the
heterologous moiety.
[0080] In another embodiment, sequences encoding HSEBP may be
synthesized, in whole or in part, using chemical methods well known
in the art (see Caruthers, M. H. et al. (1980) Nuc. Acids Res.
Symp. Ser. 7:215-223, Horn, T. et al. (1980) Nuc. Acids Res. Symp.
Ser. 7:225-232). Alternatively, the protein itself may be produced
using chemical methods to synthesize the amino acid sequence of
HSEBP, or a portion thereof. For example, peptide synthesis can be
performed using various solid-phase techniques (Roberge, J. Y. et
al. (1995) Science 269:202-204) and automated synthesis may be
achieved, for example, using the ABI 431A Peptide Synthesizer
(Perkin Elmer).
[0081] The newly synthesized peptide may be substantially purified
by preparative high performance liquid chromatography (e.g.,
Creighton, T. (1983) Proteins, Structures and Molecular Principles,
WH Freeman and Co., New York, N.Y.). The composition of the
synthetic peptides may be confirmed by amino acid analysis or
sequencing (e.g., the Edman degradation procedure; Creighton,
supra). Additionally, the amino acid sequence of HSEBP, or any part
thereof, may be altered during direct synthesis and/or combined
using chemical methods with sequences from other proteins, or any
part thereof, to produce a variant polypeptide.
[0082] In order to express a biologically active HSEBP, the
nucleotide sequences encoding HSEBP or functional equivalents, may
be inserted into appropriate expression vector, i.e., a vector
which contains the necessary elements for the transcription and
translation of the inserted coding sequence.
[0083] Methods which are well known to those skilled in the art may
be used to construct expression vectors containing sequences
encoding HSEBP and appropriate transcriptional and translational
control elements. These methods include in vitro recombinant DNA
techniques, synthetic techniques, and in vivo genetic
recombination. Such techniques are described in Sambrook, J. et al.
(1989) Molecular Cloning, A Laboratory Manual, Cold Spring Harbor
Press, Plainview, N.Y., and Ausubel, F. M. et al. (1989) Current
Protocols in Molecular Biology, John Wiley & Sons, New York,
N.Y.
[0084] A variety of expression vector/host systems may be utilized
to contain and express sequences encoding HSEBP. These include, but
are not limited to, microorganisms such as bacteria transformed
with recombinant bacteriophage, plasmid, or cosmid DNA expression
vectors; yeast transformed with yeast expression vectors; insect
cell systems infected with virus expression vectors (e.g.,
baculovirus); plant cell systems transformed with virus expression
vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic
virus, TMV) or with bacterial expression vectors (e.g., Ti or
pBR322 plasmids); or animal cell systems.
[0085] The "control elements" or "regulatory sequences" are those
non-translated regions of the vector--enhancers, promoters, 5' and
3' untranslated regions--which interact with host cellular proteins
to carry out transcription and translation. Such elements may vary
in their strength and specificity. Depending on the vector system
and host utilized, any number of suitable transcription and
translation elements, including constitutive and inducible
promoters, may be used. For example, when cloning in bacterial
systems, inducible promoters such as the hybrid lacZ promoter of
the Bluescript.RTM. phagemid (Stratagene, La Jolla, Calif.) or
pSport1.TM. plasmid (Gibco BRL) and the like may be used. The
baculovirus polyhedrin promoter may be used in insect cells.
Promoters or enhancers derived from the genomes of plant cells
(e.g., heat shock, RUBISCO; and storage protein genes) or from
plant viruses (e.g., viral promoters or leader sequences) may be
cloned into the vector. In mammalian cell systems, promoters from
mammalian genes or from mammalian viruses are preferable. If it is
necessary to generate a cell line that contains multiple copies of
the sequence encoding HSEBP, vectors based on SV40 or EBV may be
used with an appropriate selectable marker.
[0086] In bacterial systems, a number of expression vectors may be
selected depending upon the use intended for HSEBP. For example,
when large quantities of HSEBP are needed for the induction of
antibodies, vectors which direct high level expression of fusion
proteins that are readily purified may be used. Such vectors
include, but are not limited to, the multifunctional E. coli
cloning and expression vectors such as Bluescript.RTM.
(Stratagene), in which the sequence encoding HSEBP may be ligated
into the vector in frame with sequences for the amino-terminal Met
and the subsequent 7 residues of .beta.-galactosidase so that a
hybrid protein is produced; pIN vectors (Van Heeke, G. and S. M.
Schuster (1989) J. Biol. Chem. 264:5503-5509); and the like. pGEX
vectors (Promega, Madison, Wis.) may also be used to express
foreign polypeptides as fusion proteins with glutathione
S-transferase (GST). In general, such fusion proteins are soluble
and can easily be purified from lysed cells by adsorption to
glutathione-agarose beads followed by elution in the presence of
free glutathione. Proteins made in such systems may be designed to
include heparin, thrombin, or factor XA protease cleavage sites so
that the cloned polypeptide of interest can be released from the
GST moiety at will.
[0087] In the yeast, Saccharomyces cerevisiae, a number of vectors
containing constitutive or inducible promoters such as alpha
factor, alcohol oxidase, and PGH may be used. For reviews, see
Ausubel et al. (supra) and Grant et al. (1987) Methods Enzymol.
153:516-544.
[0088] In cases where plant expression vectors are used, the
expression of sequences encoding HSEBP may be driven by any of a
number of promoters. For example, viral promoters such as the 35S
and 19S promoters of CaMV may be used alone or in combination with
the omega leader sequence from TMV (Takamatsu, N. (1987) EMBO J.
6:307-311). Alternatively, plant promoters such as the small
subunit of RUBISCO or heat shock promoters may be used (Coruzzi, G.
et al. (1984) EMBO J. 3:1671-1680; Broglie, R. et al. (1984)
Science 224:838-843; and Winter, J. et al. (1991) Results Probl.
Cell Differ. 17:85-105). These constructs can be introduced into
plant cells by direct DNA transformation or pathogen-mediated
transfection. Such techniques are described in a number of
generally available reviews (see, for example, Hobbs, S. or Murry,
L. E. in McGraw Hill Yearbook of Science and Technology (1992)
McGraw Hill, New York, N.Y.; pp. 191-196.
[0089] An insect system may also be used to express HSEBP. For
example, in one such system, Autographa californica nuclear
polyhedrosis virus (AcNPV) is used as a vector to express foreign
genes in Spodoptera frugiperda cells or in Trichoplusia larvae. The
sequences encoding HSEBP may be cloned into a non-essential region
of the virus, such as the polyhedrin gene, and placed under control
of the polyhedrin promoter. Successful insertion of HSEBP will
render the polyhedrin gene inactive and produce recombinant virus
lacking coat protein. The recombinant viruses may then be used to
infect, for example, S. frugiperda cells or Trichoplusia larvae in
which HSEBP may be expressed (Engelhard, E. K. et al. (1994) Proc.
Nat. Acad. Sci. 91:3224-3227).
[0090] In mammalian host cells, a number of viral-based expression
systems may be utilized. In cases where an adenovirus is used as an
expression vector, sequences encoding HSEBP may be ligated into an
adenovirus transcription/translation complex consisting of the late
promoter and tripartite leader sequence. Insertion in a
non-essential E1 or E3 region of the viral genome may be used to
obtain a viable virus which is capable of expressing HSEBP in
infected host cells (Logan, J. and T. Shenk (1984) Proc. Natl.
Acad. Sci. 81:3655-3659). In addition, transcription enhancers,
such as the Rous sarcoma virus (RSV) enhancer, may be used to
increase expression in mammalian host cells.
[0091] Specific initiation signals may also be used to achieve more
efficient translation of sequences encoding HSEBP. Such signals
include the ATG initiation codon and adjacent sequences. In cases
where sequences encoding HSEBP, its initiation codon, and upstream
sequences are inserted into the appropriate expression vector, no
additional transcriptional or translational control signals may be
needed. However, in cases where only coding sequence, or a portion
thereof, is inserted, exogenous translational control signals
including the ATG initiation codon should be provided. Furthermore,
the initiation codon should be in the correct reading frame to
ensure translation of the entire insert. Exogenous translational
elements and initiation codons may be of various origins, both
natural and synthetic. The efficiency of expression may be enhanced
by the inclusion of enhancers which are appropriate for the
particular cell system which is used, such as those described in
the literature (Scharf, D. et al. (1994) Results Probl. Cell
Differ. 20:125-162).
[0092] In addition, a host cell strain may be chosen for its
ability to modulate the expression of the inserted sequences or to
process the expressed protein in the desired fashion. Such
modifications of the polypeptide include, but are not limited to,
acetylation, carboxylation, glycosylation, phosphorylation,
lipidation, and acylation. Post-translational processing which
cleaves a "prepro" form of the protein may also be used to
facilitate correct insertion, folding and/or function. Different
host cells such as CHO, HeLa, MDCK, HEK293, and WI38, which have
specific cellular machinery and characteristic mechanisms for such
post-translational activities, may be chosen to ensure the correct
modification and processing of the foreign protein.
[0093] For long-term, high-yield production of recombinant
proteins, stable expression is preferred. For example, cell lines
which stably express HSEBP may be transformed using expression
vectors which may contain viral origins of replication and/or
endogenous expression elements and a selectable marker gene on the
same or on a separate vector. Following the introduction of the
vector, cells may be allowed to grow for 1-2 days in an enriched
media before they are switched to selective media. The purpose of
the selectable marker is to confer resistance to selection, and its
presence allows growth and recovery of cells which successfully
express the introduced sequences. Resistant clones of stably
transformed cells may be proliferated using tissue culture
techniques appropriate to the cell type.
[0094] Any number of selection systems may be used to recover
transformed cell lines. These include, but are not limited to, the
herpes simplex virus thymidine kinase (Wigler, M. et al. (1977)
Cell 11:223-32) and adenine phosphoribosyltransferase (Lowy, I. et
al. (1980) Cell 22:817-23) genes which can be employed in t .sup.-
or aprt.sup.- cells, respectively. Also, antimetabolite, antibiotic
or herbicide resistance can be used as the basis for selection; for
example, dhfr which confers resistance to methotrexate (Wigler, M.
et al. (1980) Proc. Natl. Acad. Sci. 77:3567-70); npt, which
confers resistance to the aminoglycosides neomycin and G-418
(Colbere-Garapin, F. et al. (1981) J. Mol. Biol. 150:1-14) and als
or pat, which confers resistance to chlorsulfuron and
phosphinotricin acetyltransferase, respectively (Murry, supra).
Additional selectable genes have been described, for example, trpB,
which allows cells to utilize indole in place of tryptophan, or
hisD, which allows cells to utilize histinol in place of histidine
(Hartman, S. C. and R. C. Mulligan (1988) Proc. Natl. Acad. Sci.
85:8047-51). Recently, the use of visible markers has gained
popularity with such markers as anthocyanins, .beta.-glucuronidase
and its substrate GUS, and luciferase and its substrate luciferin,
being widely used not only to identify transformants, but also to
quantify the amount of transient or stable protein expression
attributable to a specific vector system (Rhodes, C. A. et al.
(1995) Methods Mol. Biol. 55:121-131).
[0095] Although the presence/absence of marker gene expression
suggests that the gene of interest is also present, its presence
and expression may need to be confirmed. For example, if the
sequence encoding HSEBP is inserted within a marker gene sequence,
recombinant cells containing sequences encoding HSEBP can be
identified by the absence of marker gene function. Alternatively, a
marker gene can be placed in tandem with a sequence encoding HSEBP
under the control of a single promoter. Expression of the marker
gene in response to induction or selection usually indicates
expression of the tandem gene as well.
[0096] Alternatively, host cells which contain the nucleic acid
sequence encoding HSEBP and express HSEBP may be identified by a
variety of procedures known to those of skill in the art. These
procedures include, but are not limited to, DNA-DNA or DNA-RNA
hybridizations and protein bioassay or immunoassay techniques which
include membrane, solution, or chip based technologies for the
detection and/or quantification of nucleic acid or protein.
[0097] The presence of polynucleotide sequences encoding HSEBP can
be detected by DNA-DNA or DNA-RNA hybridization or amplification
using probes or portions or fragments of polynucleotides encoding
HSEBP. Nucleic acid amplification based assays involve the use of
oligonucleotides or oligomers based on the sequences encoding HSEBP
to detect transformants containing DNA or RNA encoding HSEBP. As
used herein "oligonucleotides" or "oligomers" refer to a nucleic
acid sequence of at least about 10 nucleotides and as many as about
60 nucleotides, preferably about 15 to 30 nucleotides, and more
preferably about 20-25 nucleotides, which can be used as a probe or
amplimer.
[0098] A variety of protocols for detecting and measuring the
expression of HSEBP, using either polyclonal or monoclonal
antibodies specific for the protein are known in the art. Examples
include enzyme-linked immunosorbent assay (ELISA), radioimmunoassay
(RIA), and fluorescence activated cell sorting (FACS). A two-site,
monoclonal-based immunoassay utilizing monoclonal antibodies
reactive to two non-interfering epitopes on HSEBP is preferred, but
a competitive binding assay may be employed. These and other assays
are described, among other places, in Hampton, R. et al. (1990;
Serological Methods, a Laboratory Manual, APS Press, St Paul,
Minn.) and Maddox, D. E. et al. (1983; J. Exp. Med.
158:1211-1216).
[0099] A wide variety of labels and conjugation techniques are
known by those skilled in the art and may be used in various
nucleic acid and amino acid assays. Means for producing labeled
hybridization or PCR probes for detecting sequences related to
polynucleotides encoding HSEBP include oligolabeling, nick
translation, end-labeling or PCR amplification using a labeled
nucleotide. Alternatively, the sequences encoding HSEBP, or any
portions thereof may be cloned into a vector for the production of
an mRNA probe. Such vectors are known in the art, are commercially
available, and may be used to synthesize RNA probes in vitro by
addition of an appropriate RNA polymerase such as T7, T3, or SP6
and labeled nucleotides. These procedures may be conducted using a
variety of commercially available kits (Pharmacia & Upjohn,
(Kalamazoo, Mich.); Promega (Madison Wis.); and U.S. Biochemical
Corp., Cleveland, Ohio). Suitable reporter molecules or labels,
which may be used, include radionuclides, enzymes, fluorescent,
chemiluminescent, or chromogenic agents as well as substrates,
cofactors, inhibitors, magnetic particles, and the like.
[0100] Host cells transformed with nucleotide sequences encoding
HSEBP may be cultured under conditions suitable for the expression
and recovery of the protein from cell culture. The protein produced
by a recombinant cell may be secreted or contained intracellularly
depending on the sequence and/or the vector used. As will be
understood by those of skill in the art, expression vectors
containing polynucleotides which encode HSEBP may be designed to
contain signal sequences which direct secretion of HSEBP through a
prokaryotic or eukaryotic cell membrane. Other recombinant
constructions may be used to join sequences encoding HSEBP to
nucleotide sequences encoding a polypeptide domain which will
facilitate purification of soluble proteins. Such purification
facilitating domains include, but are not limited to, metal
chelating peptides such as histidine-tryptophan modules that allow
purification on immobilized metals, protein A domains that allow
purification on immobilized immunoglobulin, and the domain utilized
in the FLAGS extension/affinity purification system (Immunex Corp.,
Seattle, Wash.). The inclusion of cleavable linker sequences such
as those specific for Factor XA or enterokinase (Invitrogen, San
Diego, Calif.) between the purification domain and HSEBP may be
used to facilitate purification. One such expression vector
provides for expression of a fusion protein containing HSEBP and a
nucleic acid encoding 6 histidine residues preceding a thioredoxin
or an enterokinase cleavage site. The histidine residues facilitate
purification on IMAC (immobilized metal ion affinity chromatography
as described in Porath, J. et al. (1992, Prot. Exp. Purif.
3:263-281) while the enterokinase cleavage site provides a means
for purifying HSEBP from the fusion protein. A discussion of
vectors which contain fusion proteins is provided in Kroll, D. J.
et al. (1993; DNA Cell Biol. 12:441-453).
[0101] In addition to recombinant production, fragments of HSEBP
may be produced by direct peptide synthesis using solid-phase
techniques (Merrifield, J. (1963) J. Am. Chem. Soc. 85:2149-2154).
Protein synthesis may be performed using manual techniques or by
automation. Automated synthesis may be achieved, for example, using
Applied Biosystems 431A Peptide Synthesizer (Perkin Elmer). Various
fragments of HSEBP may be chemically synthesized separately and
combined using chemical methods to produce the full length
molecule.
[0102] Therapeutics
[0103] HSEBP or fragments thereof may be used for therapeutic
purposes. Based on the chemical and structural homology among HSEBP
(SEQ ID NO:1) and other selenium-binding proteins and northern
analysis (FIG. 5) which shows that most of the libraries containing
HSEBP transcripts are associated with cancer and/or the
gastrointestinal and respiratory tracts, HSEBP is believed to have
a role in protecting a subject from the body's response to chemical
toxins and cancer.
[0104] In one embodiment, HSEBP, or a fragment or derivative
thereof, may be administered to a subject to prevent or treat liver
necrosis and kidney or lung damage caused by chemical agents
including, but not limited to, acetaminophen and carcinogens such
as PCBs. Similarly, a vector capable of expressing HSEBP may be
administered to a subject to prevent or treat liver necrosis and
kidney or lung damage caused by chemical agents. Once administered,
HSEBP will serve as a substrate for arylation by acetamninophen and
its metabolites, sparing endogenous HSEBP from modification, and
thereby protecting the tissue from life-threatening damage.
[0105] Expression of HSEBP has been shown to be highly correlated
with cancer (FIG. 5). Therefore, vectors containing the nucleic
acid sequence encoding HSEBP may be administered to a subject to
prevent or inhibit tumor growth. These vectors can be delivered
into the tissue(s) of a subject that has a predisposition to
cancer, or they may be administered directly into tumors or
cancerous cells using technologies well known in the art. HSEBP
administered by vector may serve as an intracellular reservoir of
Se.
[0106] In another embodiment, HSEBP may be administered in
combination therapy with other chemotherapeutic agents. Such
combinations of therapeutic agents having different mechanisms of
action for the treatment of cancer will have synergistic effects
allowing the use of lower effective doses of each agent and
lessening side effects.
[0107] In another embodiment, agonists of HSEBP may be used in
those situations where such modulation is therapeutically
desirable. Such agonists may be produced using methods which are
generally known in the art. A particular method involves the use of
purified HSEBP to screen libraries of pharmaceutical agents for
those which specifically bind HSEBP.
[0108] Purified HSEBP can also be used to produce antibodies that
are specific for HSEBP. The specific antibodies may be used to
target or deliver a pharmaceutical agent to particular cells or
tissues which express HSEBP. The antibodies may be generated using
methods that are well known in the art. Such antibodies may
include, but are not limited to, polyclonal, monoclonal, chimeric,
single chain, Fab fragments, and fragments produced by a Fab
expression library. Neutralizing antibodies, (i.e., those which
inhibit dimer formation) are especially preferred for therapeutic
use.
[0109] For the production of antibodies, various hosts including
goats, rabbits, rats, mice, humans, and others, may be immunized by
injection with HSEBP or any fragment or oligopeptide thereof which
has immunogenic properties. Depending on the host species, various
adjuvants may be used to increase immunological response. Such
adjuvants include, but are not limited to, Freund's, mineral gels
such as aluminum hydroxide, and surface active substances such as
lysolecithin, pluronic polyols, polyanions, peptides, oil
emulsions, keyhole limpet hemocyanin, and dinitrophenol. Among
adjuvants used in humans, BCG (bacilli Calmette-Guerin) and
Corynebacterium parvum are especially preferable.
[0110] It is preferred that the peptides, fragments, or
oligopeptides used to induce antibodies to HSEBP have an amino acid
sequence consisting of at least five amino acids, and more
preferably at least 10 amino acids. It is also preferable that they
are identical to a portion of the amino acid sequence of the
natural protein, and they may contain the entire amino acid
sequence of a small, naturally occurring molecule. Short stretches
of HSEBP amino acids may be fused with those of another protein
such as keyhole limpet hemocyanin and antibody produced against the
chimeric molecule.
[0111] Monoclonal antibodies to HSEBP may be prepared using any
technique which provides for the production of antibody molecules
by continuous cell lines in culture. These include, but are not
limited to, the hybridoma technique, the human B-cell hybridoma
technique, and the EBV-hybridoma technique (Kohler, G. et al.
(1975) Nature 256:495-497; Kozbor, D. et al. (1985) J. Immunol.
Methods 81:31-42; Cote, R. J. et al. (1983) Proc. Natl. Acad. Sci.
80:2026-2030; Cole, S. P. et al. (1984) Mol. Cell Biol.
62:109-120).
[0112] In addition, techniques developed for the production of
"chimeric antibodies", the splicing of mouse antibody genes to
human antibody genes to obtain a molecule with appropriate antigen
specificity and biological activity can be used (Morrison, S. L. et
al. (1984) Proc. Natl. Acad. Sci. 81:6851-6855; Neuberger, M. S. et
al. (1984) Nature 312:604-608; Takeda, S. et al. (1985) Nature
314:452-454). Alternatively, techniques described for the
production of single chain antibodies may be adapted, using methods
known in the art, to produce HSEBP-specific single chain
antibodies. Antibodies with related specificity, but of distinct
idiotypic composition, may be generated by chain shuffling from
random combinatorial immunoglobulin libraries (Kang A. S. et al.
(1991) Proc. Natl. Acad. Sci. 88:11120-3).
[0113] Antibodies may also be produced by inducing in vivo
production in the lymphocyte population or by screening recombinant
immunoglobulin libraries or panels of highly specific binding
reagents as disclosed in the literature (Orlandi, R. et al. (1989)
Proc. Natl. Acad. Sci. 86: 3833-3837; Winter, G. et al. (1991)
Nature 349:293-299).
[0114] Antibody fragments which contain specific binding sites for
HSEBP may also be generated. For example, such fragments include,
but are not limited to, the F(ab')2 fragments which can be produced
by pepsin digestion of the antibody molecule and the Fab fragments
which can be generated by reducing the disulfide bridges of the
F(ab')2 fragments. Alternatively, Fab expression libraries may be
constructed to allow rapid and easy identification of monoclonal
Fab fragments with the desired specificity (Huse, W. D. et al.
(1989) Science 254:1275-1281).
[0115] Various immunoassays may be used for screening to identify
antibodies having the desired specificity. Numerous protocols for
competitive binding or immunoradiometric assays using either
polyclonal or monoclonal antibodies with established specificities
are well known in the art. Such immunoassays typically involve the
measurement of complex formation between HSEBP and its specific
antibody. A two-site, monoclonal-based immunoassay utilizing
monoclonal antibodies reactive to two non-interfering HSEBP
epitopes is preferred, but a competitive binding assay may also be
employed (Maddox, supra).
[0116] In another embodiment of the invention, the polynucleotides
encoding HSEBP, or any fragment thereof, or antisense molecules,
may be used for therapeutic purposes. In one aspect, antisense to
the polynucleotide encoding HSEBP may be used in situations in
which it would be desirable to block the transcription of the mRNA.
In particular, cells may be transformed with sequences
complementary to polynucleotides encoding HSEBP. Thus, antisense
molecules may be used to modulate HSEBP activity, or to achieve
regulation of gene function. Such technology is now well known in
the art, and sense or antisense oligomers or larger fragments, can
be designed from various locations along the coding or control
regions of sequences encoding HSEBP.
[0117] Expression vectors derived from retroviruses, adenovirus,
herpes or vaccinia viruses, or from various bacterial plasmids may
be used for delivery of nucleotide sequences to the targeted organ,
tissue or cell population. Methods which are well known to those
skilled in the art can be used to construct recombinant vectors
which will express antisense molecules complementary to the
polynucleotides of the gene encoding HSEBP. These techniques are
described both in Sambrook, J. et al. (supra) and in Ausubel et al.
(supra).
[0118] Genes encoding HSEBP can be turned off by transforming a
cell or tissue with expression vectors which express high levels of
a polynucleotide or fragment thereof which encodes HSEBP. Such
constructs may be used to introduce untranslatable sense or
antisense sequences into a cell. Even in the absence of integration
into the DNA, such vectors may continue to transcribe RNA molecules
until they are disabled by endogenous nucleases. Transient
expression may last for a month or more with a non-replicating
vector and even longer if appropriate replication elements are part
of the vector system.
[0119] As mentioned above, modifications of gene expression can be
obtained by designing antisense molecules, DNA, RNA, or PNA, to the
control regions of the gene encoding HSEBP, i.e., the promoters,
enhancers, and introns. Oligonucleotides derived from the
transcription initiation site, e.g., between positions -10 and +10
from the start site, are preferred. Similarly, inhibition can be
achieved using "triple helix" base-pairing methodology. Triple
helix pairing is useful because it causes inhibition of the ability
of the double helix to open sufficiently for the binding of
polymerases, transcription factors, or regulatory molecules. Recent
therapeutic advances using triplex DNA have been described in the
literature (Gee, J. E. et al. (1994) In: Huber, B. E. and B. I.
Carr, Molecular and Immunologic Approaches, Future Publishing Co.,
Mt. Kisco, N.Y.). The antisense molecules may also be designed to
block translation of mRNA by preventing the transcript from binding
to ribosomes.
[0120] Ribozymes, enzymatic RNA molecules, may also be used to
catalyze the specific cleavage of RNA. The mechanism of ribozyme
action involves sequence-specific hybridization of the ribozyme
molecule to complementary target RNA, followed by endonucleolytic
cleavage. Examples which may be used include engineered hammerhead
motif ribozyme molecules that can specifically and efficiently
catalyze endonucleolytic cleavage of sequences encoding HSEBP.
[0121] Specific ribozyme cleavage sites within any potential RNA
target are initially identified by scanning the target molecule for
ribozyme cleavage sites which include the following sequences: GUN,
GUN, and GUN. Once identified, short RNA sequences of between 15
and 20 ribonucleotides corresponding to the region of the target
gene containing the cleavage site may be evaluated for secondary
structural features which may render the oligonucleotide
inoperable. The suitability of candidate targets may also be
evaluated by testing accessibility to hybridization with
complementary oligonucleotides using ribonuclease protection
assays.
[0122] Antisense molecules and ribozymes of the invention may be
prepared by any method known in the art for the synthesis of
nucleic acid molecules. These include techniques for chemically
synthesizing oligonucleotides such as solid phase phosphoramidite
chemical synthesis. Alternatively, RNA molecules may be generated
by in vitro and in vivo transcription of DNA sequences encoding
HSEBP. Such DNA sequences may be incorporated into a wide variety
of vectors with suitable RNA polymerase promoters such as T7 or
SP6. Alternatively, these cDNA constructs that synthesize antisense
RNA constitutively or inducible can be introduced into cell lines,
cells, or tissues.
[0123] RNA molecules may be modified to increase intracellular
stability and half-life. Possible modifications include, but are
not limited to, the addition of flanking sequences at the 5' and/or
3' ends of the molecule or the use of phosphorothioate or
2'O-methyl phosphodiester linkages within the backbone of the
molecule. This concept is inherent in the production of PANS and
can be extended in all of these molecules by the inclusion of
nontraditional bases such as inosine, queosine, and wybutosine, as
well as acetyl-, methyl-, thin-, and similarly modified forms of
adenine, cytidine, guanine, thymine, and uridine which are not as
easily recognized by endogenous endonucleases.
[0124] Many methods for introducing vectors into cells or tissues
are available and equally suitable for use in vivo, in vitro, and
ex vivo. For ex vivo therapy, vectors may be introduced into stem
cells taken from the patient and clonally propagated for autologous
transplant back into that same patient. Delivery by transfection
and by liposome injections may be achieved using methods which are
well known in the art.
[0125] Any of the therapeutic methods described above may be
applied to any suitable subject including, for example, mammals
such as dogs, cats, cows, horses, rabbits, monkeys, and most
preferably, humans.
[0126] An additional embodiment of the invention relates to the
administration of a pharmaceutical composition, in conjunction with
a pharmaceutically acceptable carrier, for any of the therapeutic
effects discussed above. Such pharmaceutical compositions may
consist of HSEBP, antibodies to HSEBP, mimetics, agonists,
antagonists, or inhibitors of HSEBP. The compositions may be
administered alone or in combination with at least one other agent,
such as stabilizing compound, which may be administered in any
sterile, biocompatible pharmaceutical carrier, including, but not
limited to, saline, buffered saline, dextrose, and water. The
compositions may be administered to a patient alone, or in
combination with other agents, drugs or hormones.
[0127] The pharmaceutical compositions utilized in this invention
may be administered by any number of routes including, but not
limited to, oral, intravenous, intramuscular, intra-arterial,
intramedullary, intrathecal, intraventricular, transdermal,
subcutaneous, intraperitoneal, intranasal, enteral, topical,
sublingual, or rectal means.
[0128] In addition to the active ingredients, these pharmaceutical
compositions may contain suitable pharmaceutically-acceptable
carriers comprising excipients and auxiliaries which facilitate
processing of the active compounds into preparations which can be
used pharmaceutically. Further details on techniques for
formulation and administration may be found in the latest edition
of Remington's Pharmaceutical Sciences (Maack Publishing Co.,
Easton, Pa.).
[0129] Pharmaceutical compositions for oral administration can be
formulated using pharmaceutically acceptable carriers well known in
the art in dosages suitable for oral administration. Such carriers
enable the pharmaceutical compositions to be formulated as tablets,
pills, dragees, capsules, liquids, gels, syrups, slurries,
suspensions, and the like, for ingestion by the patient.
[0130] Pharmaceutical preparations for oral use can be obtained
through combination of active compounds with solid excipient,
optionally grinding a resulting mixture, and processing the mixture
of granules, after adding suitable auxiliaries, if desired, to
obtain tablets or dragee cores. Suitable excipients are
carbohydrate or protein fillers, such as sugars, including lactose,
sucrose, mannitol, or sorbitol; starch from corn, wheat, rice,
potato, or other plants; cellulose, such as methyl cellulose,
hydroxypropylmethyl-cellulose, or sodium carboxymethylcellulose;
gums including arabic and tragacanth; and proteins such as gelatin
and collagen. If desired, disintegrating or solubilizing agents may
be added, such as the cross-linked polyvinyl pyrrolidone, agar,
alginic acid, or a salt thereof, such as sodium alginate.
[0131] Dragee cores may be used in conjunction with suitable
coatings, such as concentrated sugar solutions, which may also
contain gum arabic, talc, polyvinylpyrrolidone, carbopol gel,
polyethylene glycol, and/or titanium dioxide, lacquer solutions,
and suitable organic solvents or solvent mixtures. Dyestuffs or
pigments may be added to the tablets or dragee coatings for product
identification or to characterize the quantity of active compound,
i.e., dosage.
[0132] Pharmaceutical preparations which can be used orally include
push-fit capsules made of gelatin, as well as soft, sealed capsules
made of gelatin and a coating, such as glycerol or sorbitol.
Push-fit capsules can contain active ingredients mixed with a
filler or binders, such as lactose or starches, lubricants, such as
talc or magnesium stearate, and, optionally, stabilizers. In soft
capsules, the active compounds may be dissolved or suspended in
suitable liquids, such as fatty oils, liquid, or liquid
polyethylene glycol with or without stabilizers.
[0133] Pharmaceutical formulations suitable for parenteral
administration may be formulated in aqueous solutions, preferably
in physiologically compatible buffers such as Hanks's solution,
Ringer's solution, or physiologically buffered saline. Aqueous
injection suspensions may contain substances which increase the
viscosity of the suspension, such as sodium carboxymethyl
cellulose, sorbitol, or dextran. Additionally, suspensions of the
active compounds may be prepared as appropriate oily injection
suspensions. Suitable lipophilic solvents or vehicles include fatty
oils such as sesame oil, or synthetic fatty acid esters, such as
ethyl oleate or triglycerides, or liposomes. Optionally, the
suspension may also contain suitable stabilizers or agents which
increase the solubility of the compounds to allow for the
preparation of highly concentrated solutions.
[0134] For topical or nasal administration, penetrants appropriate
to the particular barrier to be permeated are used in the
formulation. Such penetrants are generally known in the art.
[0135] The pharmaceutical compositions of the present invention may
be manufactured in a manner that is known in the art, e.g., by
means of conventional mixing, dissolving, granulating,
dragee-making, levigating, emulsifying, encapsulating, entrapping,
or lyophilizing processes.
[0136] The pharmaceutical composition may be provided as a salt and
can be formed with many acids, including but not limited to,
hydrochloric, sulfuric, acetic, lactic, tartaric, malic, succinic,
etc. Salts tend to be more soluble in aqueous or other protonic
solvents than are the corresponding free base forms. In other
cases, the preferred preparation may be a lyophilized powder which
may contain any or all of the following: 1-50 mM histidine, 0.1%-2%
sucrose, and 2-7% mannitol, at a pH range of 4.5 to 5.5, that is
combined with buffer prior to use.
[0137] After pharmaceutical compositions have been prepared, they
can be placed in an appropriate container and labeled for treatment
of an indicated condition. For administration of HSEBP, such
labeling would include amount, frequency, and method of
administration.
[0138] Pharmaceutical compositions suitable for use in the
invention include compositions wherein the active ingredients are
contained in an effective amount to achieve the intended purpose.
The determination of an effective dose is well within the
capability of those skilled in the art.
[0139] For any compound, the therapeutically effective dose can be
estimated initially either in cell culture assays, e.g., of
neoplastic cells, or in animal models, usually mice, rabbits, dogs,
or pigs. The animal model may also be used to determine the
appropriate concentration range and route of administration. Such
information can then be used to determine useful doses and routes
for administration in humans.
[0140] A therapeutically effective dose refers to that amount of
active ingredient, for example HSEBP or fragments thereof,
antibodies of HSEBP, agonists, antagonists or inhibitors of HSEBP,
which ameliorates the symptoms or condition. Therapeutic efficacy
and toxicity may be determined by standard pharmaceutical
procedures in cell cultures or experimental animals, e.g., ED50
(the dose therapeutically effective in 50% of the population) and
LD50 (the dose lethal to 50% of the population). The dose ratio
between therapeutic and toxic effects is the therapeutic index, and
it can be expressed as the ratio, LD50/ED50. Pharmaceutical
compositions which exhibit large therapeutic indices are preferred.
The data obtained from cell culture assays and animal studies is
used in formulating a range of dosage for human use. The dosage
contained in such compositions is preferably within a range of
circulating concentrations that include the ED50 with little or no
toxicity. The dosage varies within this range depending upon the
dosage form employed, sensitivity of the patient, and the route of
administration.
[0141] The exact dosage will be determined by the practitioner, in
light of factors related to the subject that requires treatment.
Dosage and administration are adjusted to provide sufficient levels
of the active moiety or to maintain the desired effect. Factors
which may be taken into account include the severity of the disease
state, general health of the subject, age, weight, and gender of
the subject, diet, time and frequency of administration, drug
combination(s), reaction sensitivities, and tolerance/response to
therapy. Long-acting pharmaceutical compositions may be
administered every 3 to 4 days, every week, or once every two weeks
depending on half-life and clearance rate of the particular
formulation.
[0142] Normal dosage amounts may vary from 0.1 to 100,000
micrograms, up to a total dose of about 1 g, depending upon the
route of administration. Guidance as to particular dosages and
methods of delivery is provided in the literature and generally
available to practitioners in the art. Those skilled in the art
will employ different formulations for nucleotides than for
proteins or their inhibitors. Similarly, delivery of
polynucleotides or polypeptides will be specific to particular
cells, conditions, locations, etc.
[0143] Diagnostics
[0144] In another embodiment, antibodies which specifically bind
HSEBP may be used for the diagnosis of conditions or diseases
characterized by expression of HSEBP, or in assays to monitor
patients being treated with HSEBP or agonists thereof. The
antibodies useful for diagnostic purposes may be prepared in the
same manner as those described above for therapeutics. Diagnostic
assays for HSEBP include methods which utilize the antibody and a
label to detect HSEBP in human body fluids or extracts of cells or
tissues. The antibodies may be used with or without modification,
and may be labeled by joining them, either covalently or
non-covalently, with a reporter molecule. A wide variety of
reporter molecules which are known in the art may be used, several
of which are described above.
[0145] A variety of protocols including ELISA, RIA, and FACS for
measuring HSEBP are known in the art and provide a basis for
diagnosing altered or abnormal levels of HSEBP expression. Normal
or standard values for HSEBP expression are established by
combining body fluids or cell extracts taken from normal mammalian
subjects, preferably human, with antibody to HSEBP under conditions
suitable for complex formation. The amount of standard complex
formation may be quantified by various methods, but preferably by
photometric, means. Quantities of HSEBP expressed in subject,
control and disease, samples from biopsied tissues are compared
with the standard values. Deviation between standard and subject
values establishes the parameters for diagnosing disease.
[0146] In another embodiment of the invention, the polynucleotides
encoding HSEBP may be used for diagnostic purposes. The
polynucleotides which may be used include oligonucleotide
sequences, antisense RNA and DNA molecules, and PNAs. The
polynucleotides may be used to detect and quantitate gene
expression in biopsied tissues in which expression of HSEBP may be
correlated with disease. The diagnostic assay may be used to
distinguish between absence, presence, and excess expression of
HSEBP, and to monitor regulation of HSEBP levels during therapeutic
intervention.
[0147] In one aspect, hybridization with PCR probes which are
capable of detecting polynucleotide sequences, including genomic
sequences, encoding HSEBP or closely related molecules, may be used
to identify nucleic acid sequences which encode HSEBP. The
specificity of the probe, whether it is made from a highly specific
region, e.g., 10 unique nucleotides in the 5' regulatory region, or
a less specific region, e.g., especially in the 3' coding region,
and the stringency of the hybridization or amplification (maximal,
high, intermediate, or low) will determine whether the probe
identifies only naturally occurring sequences encoding HSEBP,
alleles, or related sequences.
[0148] Probes may also be used for the detection of related
sequences, and should preferably contain at least 50% of the
nucleotides from any of the HSEBP encoding sequences. The
hybridization probes of the subject invention may be DNA or RNA and
derived from the nucleotide sequence of SEQ ID NO:2 or from genomic
sequence including promoter, enhancer elements, and introns of the
naturally occurring HSEBP.
[0149] Means for producing specific hybridization probes for DNAs
encoding HSEBP include the cloning of nucleic acid sequences
encoding HSEBP or HSEBP derivatives into vectors for the production
of mRNA probes. Such vectors are known in the art, commercially
available, and may be used to synthesize RNA probes in vitro by
means of the addition of the appropriate RNA polymerases and the
appropriate labeled nucleotides. Hybridization probes may be
labeled by a variety of reporter groups, for example, radionuclides
such as 32P or 35S, or enzymatic labels, such as alkaline
phosphatase coupled to the probe via avidin/biotin coupling
systems, and the like.
[0150] Polynucleotide sequences encoding HSEBP may be used for the
diagnosis of conditions or diseases which are associated with
expression of HSEBP. Examples of such conditions or diseases
include cancers of the liver, kidney, lung, mammary, epithelial,
gastrointestinal, and endocrine glands. The polynucleotide
sequences encoding HSEBP may be used in Southern or northern
analysis, dot blot, or other membrane-based technologies; in PCR
technologies; or in dip stick, pin, ELISA or chip assays utilizing
fluids or tissues from patient biopsies to detect altered HSEBP
expression. Such qualitative or quantitative methods are well known
in the art.
[0151] In a particular aspect, the nucleotide sequences encoding
HSEBP may be useful in assays that detect activation or induction
of various cancers, particularly those mentioned above. The
nucleotide sequences encoding HSEBP may be labeled by standard
methods, and added to a fluid or tissue sample from a patient under
conditions suitable for the formation of hybridization complexes.
After a suitable incubation period, the sample is washed and the
signal is quantitated and compared with a standard value. If the
amount of signal in the biopsied or extracted sample is
significantly altered from that of a comparable control sample, the
nucleotide sequences have hybridized with nucleotide sequences in
the sample, and the presence of altered levels of nucleotide
sequences encoding HSEBP in the sample indicates the presence of
the associated disease. Such assays may also be used to evaluate
the efficacy of a particular therapeutic treatment regimen in
animal studies, in clinical trials, or in monitoring the treatment
of an individual patient.
[0152] In order to provide a basis for the diagnosis of disease
associated with expression of HSEBP, a normal or standard profile
for expression is established. This may be accomplished by
combining body fluids or cell extracts taken from normal subjects,
either animal or human, with a sequence, or a fragment thereof,
which encodes HSEBP, under conditions suitable for hybridization or
amplification. Standard hybridization may be quantified by
comparing the values obtained from normal subjects with those from
an experiment where a known amount of a substantially purified
polynucleotide is used. Standard values obtained from normal
samples may be compared with values obtained from samples from
patients who are symptomatic for disease. Deviation between
standard and subject values is used to establish the presence of
disease.
[0153] Once disease is established and a treatment protocol is
initiated, hybridization assays may be repeated on a regular basis
to evaluate whether the level of expression in the patient begins
to approximate that which is observed in the normal patient. The
results obtained from successive assays may be used to show the
efficacy of treatment over a period ranging from several days to
months.
[0154] With respect to cancer, the presence of a relatively high
amount of transcript in biopsied tissue from an individual may
indicate a predisposition for the development of the disease, or
may provide a means for detecting the disease prior to the
appearance of actual clinical symptoms. A more definitive diagnosis
of this type may allow health professionals to employ preventative
measures or aggressive treatment earlier thereby preventing the
development or further progression of the cancer.
[0155] Additional diagnostic uses for oligonucleotides designed
from the sequences encoding HSEBP may involve the use of PCR. Such
oligomers may be chemically synthesized, generated enzymatically,
or produced from a recombinant source. Oligomers will preferably
consist of two nucleotide sequences, one with sense orientation
(5'->3') and another with antisense (3'<-5'), employed under
optimized conditions for identification of a specific gene or
condition. The same two oligomers, nested sets of oligomers, or
even a degenerate pool of oligomers may be employed under less
stringent conditions for detection and/or quantitation of closely
related DNA or RNA sequences.
[0156] Methods which may also be used to quantitate the expression
of HSEBP include radiolabeling or biotinylating nucleotides,
coamplification of a control nucleic acid, and standard curves onto
which the experimental results are interpolated (Melby, P. C. et
al. (1993) J. Immunol. Methods, 159:235-244; Duplaa, C. et al.
(1993) Anal. Biochem. 229-236). The speed of quantitation of
multiple samples may be accelerated by running the assay in an
ELISA format where the oligomer of interest is presented in various
dilutions and a spectrophotometric or calorimetric response gives
rapid quantitation.
[0157] In another embodiment of the invention, the nucleic acid
sequences which encode HSEBP may also be used to generate
hybridization probes which are useful for mapping the naturally
occurring genomic sequence. The sequences may be mapped to a
particular chromosome or to a specific region of the chromosome
using well known techniques. Such techniques include FISH, FACS, or
artificial chromosome constructions, such as yeast artificial
chromosomes, bacterial artificial chromosomes, bacterial P1
constructions or single chromosome cDNA libraries as reviewed in
Price, C. M. (1993) Blood Rev. 7:127-134, and Trask, B. J. (1991)
Trends Genet. 7:149-154.
[0158] FISH (as described in Verma et al. (1988) Human Chromosomes:
A Manual of Basic Techniques, Pergamon Press, New York, N.Y.) may
be correlated with other physical chromosome mapping techniques and
genetic map data. Examples of genetic map data can be found in the
1994 Genome Issue of Science (265:1981f). Correlation between the
location of the gene encoding HSEBP on a physical chromosomal map
and a specific disease, or predisposition to a specific disease,
may help delimit the region of DNA associated with that genetic
disease. The nucleotide sequences of the subject invention may be
used to detect differences in gene sequences between normal,
carrier, or affected individuals.
[0159] In situ hybridization of chromosomal preparations and
physical mapping techniques such as linkage analysis using
established chromosomal markers may be used for extending genetic
maps. Often the placement of a gene on the chromosome of another
mammalian species, such as mouse, may reveal associated markers
even if the number or arm of a particular human chromosome is not
known. New sequences can be assigned to chromosomal arms, or parts
thereof, by physical mapping. This provides valuable information to
investigators searching for disease genes using positional cloning
or other gene discovery techniques. Once the disease or syndrome
has been crudely localized by genetic linkage to a particular
genomic region, for example, AT to 11q22-23 (Gatti, R. A. et al.
(1988) Nature 336:577-580), any sequences mapping to that area may
represent associated or regulatory genes for further investigation.
The nucleotide sequence of the subject invention may also be used
to detect differences in the chromosomal location due to
translocation, inversion, etc. among normal, carrier, or affected
individuals.
[0160] In another embodiment of the invention, HSEBP, its catalytic
or immunogenic fragments or oligopeptides thereof, can be used for
screening libraries of compounds in any of a variety of drug
screening techniques. The fragment employed in such screening may
be free in solution, affixed to a solid support, borne on a cell
surface, or located intracellularly. The formation of binding
complexes, between HSEBP and the agent being tested, may be
measured.
[0161] Another technique for drug screening which may be used
provides for high throughput screening of compounds having suitable
binding affinity to the protein of interest as described in
published PCT application WO84/03564. In this method, as applied to
HSEBP large numbers of different small test compounds are
synthesized on a solid substrate, such as plastic pins or some
other surface. The test compounds are reacted with HSEBP, or
fragments thereof, and washed. Bound HSEBP is then detected by
methods well known in the art. Purified HSEBP can also be coated
directly onto plates for use in the aforementioned drug screening
techniques. Alternatively, non-neutralizing antibodies can be used
to capture the peptide and immobilize it on a solid support.
[0162] In another embodiment, one may use competitive drug
screening assays in which neutralizing antibodies capable of
binding HSEBP specifically compete with a test compound for binding
HSEBP. In this manner, the antibodies can be used to detect the
presence of any peptide which shares one or more antigenic
determinants with HSEBP.
[0163] In additional embodiments, the nucleotide sequences which
encode HSEBP may be used in any molecular biology techniques that
have yet to be developed, provided the new techniques rely on
properties of nucleotide sequences that are currently known,
including, but not limited to, such properties as the triplet
genetic code and specific base pair interactions.
[0164] The examples below are provided to illustrate the subject
invention and are not included for the purpose of limiting the
invention.
EXAMPLES
[0165] I COLNNOT11 cDNA Library Construction
[0166] The COLNNOT11 cDNA library was constructed from normal colon
tissue (on microscopic examination) obtained from a 60-year-old
Caucasian male who had undergone a left hemicolectomy to remove
grade 3 (of 4) adenocarcinoma in a different part of his bowel. The
patient reported blood in his stool and changing bowel habits. The
patient history reported previous diagnoses of depressive disorder
and thrombophlebitis, accompanied by inflammatory polyarthropathies
and inflammatory disease of the prostate. The patient also had
undergone a vasectomy and resection of the rectum. The patient was
prescribed with Seldane (terfenadin; Marion Merrell Dow Inc.,
Kansas City, Mo.).
[0167] The frozen tissue was homogenized and lysed using a
Brinkmann Homogenizer Polytron PT-3000 (Brinkmann Instruments,
Westbury, N.Y.) in guanidinium isothiocyanate solution. The lysate
was centrifuged over a 5.7 M CsCl cushion using an Beckman SW28
rotor in a Beckman L8-70M Ultracentrifuge (Beckman Instruments,
Fullerton, Calif.) for 18 hours at 25,000 rpm at ambient
temperature. The RNA was extracted with acid phenol, pH 4.0,
precipitated using 0.3 M sodium acetate and 2.5 volumes of ethanol,
resuspended in RNase-free water and DNase treated at 37.degree. C.
The RNA extraction was repeated with acid phenol, pH 4.0, and
precipitated with sodium acetate and ethanol as above. The mRNA was
then isolated using the Qiagen Oligotex kit (QIAGEN Inc,
Chatsworth, Calif.) and used to construct the cDNA library.
[0168] The mRNA was handled according to the recommended protocols
in the SuperScript Plasmid System for cDNA Synthesis and Plasmid
Cloning (Cat. #18248-013; Gibco BRL). cDNAs were fractionated on a
Sepharose CL4B column (Cat. #275105-01; Pharmacia), and those cDNAs
exceeding 400 bp were ligated into pSport I. The plasmid pSport I
was subsequently transformed into DH5a.TM. competent cells (Cat.
#18258-012; Gibco BRL).
[0169] II Isolation and Sequencing of cDNA Clones
[0170] Plasmid DNA was released from the cells and purified using
the REAL Prep 96 Plasmid Kit (Cat. #26173; QIAGEN, Inc). This kit
enables the simultaneous purification of 96 samples in a 96-well
block using multi-channel reagent dispensers. The recommended
protocol was employed except for the following changes: 1) the
bacteria were cultured in 1 ml of sterile Terrific Broth (Cat.
#22711, LIFE TECHNOLOGIES.TM.) with carbenicillin at 25 mg/l and
glycerol at 0.4%; 2) after inoculation, the cultures were incubated
for 19 hours and at the end of incubation, the cells were lysed
with 0.3 ml of lysis buffer; and 3) following isopropanol
precipitation, the plasmid DNA pellet was resuspended in 0.1 ml of
distilled water. After the last step in the protocol, samples were
transferred to a 96-well block for storage at 4.degree. C.
[0171] The cDNAs were sequenced by the method of Sanger, F. and A.
R. Coulson (1975; J. Mol. Biol. 94:441f), using a Hamilton Micro
Lab 2200 (Hamilton, Reno, Nev.) in combination with Peltier Thermal
Cyclers (PTC200 from MJ Research, Watertown Mass.) and Applied
Biosystems 377 DNA Sequencing Systems; and the reading frame was
determined.
[0172] III Homology Searching of cDNA Clones and Their Deduced
Proteins
[0173] Each cDNA was compared to sequences in GenBank using a
search algorithm developed by Applied Biosystems and incorporated
into the INHERIT.TM. 670 sequence analysis system. In this
algorithm, Pattern Specification Language (TRW Inc., Los Angeles,
Calif.) was used to determine regions of homology. The three
parameters that determine how the sequence comparisons run were
window size, window offset, and error tolerance. Using a
combination of these three parameters, the DNA database was
searched for sequences containing regions of homology to the query
sequence, and the appropriate sequences were scored with an initial
value. Subsequently, these homologous regions were examined using
dot matrix homology plots to distinguish regions of homology from
chance matches. Smith-Waterman alignments were used to display the
results of the homology search.
[0174] Peptide and protein sequence homologies were ascertained
using the INHERIT-670 sequence analysis system using the methods
similar to those used in DNA sequence homologies. Pattern
Specification Language and parameter windows were used to search
protein databases for sequences containing regions of homology
which were scored with an initial value. Dot-matrix homology plots
were examined to distinguish regions of significant homology from
chance matches.
[0175] BLAST, which stands for Basic Local Alignment Search Tool
(Altschul, S. F. (1993) J. Mol. Evol. 36:290-300; Altschul et al.
(1990) J. Mol. Biol. 215:403-410), was used to search for local
sequence alignments. BLAST produces alignments of both nucleotide
and amino acid sequences to determine sequence similarity. Because
of the local nature of the alignments, BLAST is especially useful
in determining exact matches or in identifying homologs. BLAST is
useful for matches which do not contain gaps. The fundamental unit
of BLAST algorithm output is the High-scoring Segment Pair
(HSP).
[0176] An HSP consists of two sequence fragments of arbitrary but
equal lengths whose alignment is locally maximal and for which the
alignment score meets or exceeds a threshold or cutoff score set by
the user. The BLAST approach is to look for HSPs between a query
sequence and a database sequence, to evaluate the statistical
significance of any matches found, and to report only those matches
which satisfy the user-selected threshold of significance. The
parameter E establishes the statistically significant threshold for
reporting database sequence matches. E is interpreted as the upper
bound of the expected frequency of chance occurrence of an HSP (or
set of HSPs) within the context of the entire database search. Any
database sequence whose match satisfies E is reported in the
program output.
[0177] IV Northern Analysis
[0178] Northern analysis is a laboratory technique used to detect
the presence of a transcript of a gene and involves the
hybridization of a labeled nucleotide sequence to a membrane on
which RNAs from a particular cell type or tissue have been bound
(Sambrook, J. et al., supra).
[0179] Analogous computer techniques using BLAST (Altschul, S. F.
1993 and 1990, supra) are used to search for identical or related
molecules in nucleotide databases such as GenBank or the
LIFESEQ.TM. database (Incyte Pharmaceuticals). This analysis is
much faster than multiple, membrane-based hybridizations. In
addition, the sensitivity of the computer search can be modified to
determine whether any particular match is categorized as exact or
homologous.
[0180] The basis of the search is the product score which is
defined as: 1 % sequence identity .times. % maximum BLAST score
100
[0181] The product score takes into account both the degree of
similarity between two sequences and the length of the sequence
match. For example, with a product score of 40, the match will be
exact within a 1-2% error; and at 70, the match will be exact.
Homologous molecules are usually identified by selecting those
which show product scores between 15 and 40, although lower scores
may identify related molecules.
[0182] The results of northern analysis are reported as a list of
libraries in which the transcript encoding HSEBP occurs. Abundance
and percent abundance are also reported. Abundance directly
reflects the number of times a particular transcript is represented
in a cDNA library, and percent abundance is abundance divided by
the total number of sequences examined in the cDNA library.
[0183] V Extension of HSEBP-Encoding Polynucleotides to Full Length
or to Recover Regulatory Sequences
[0184] Full length HSEBP-encoding nucleic acid sequence (SEQ ID
NO:2) is used to design oligonucleotide primers for extending a
partial nucleotide sequence to full length or for obtaining 5' or
3', intron or other control sequences from genomic libraries. One
primer is synthesized to initiate extension in the antisense
direction (XLR) and the other is synthesized to extend sequence in
the sense direction (XLF). Primers are used to facilitate the
extension of the known sequence "outward" generating amplicons
containing new, unknown nucleotide sequence for the region of
interest. The initial primers are designed from the cDNA using
OLIGO 4.06 (National Biosciences), or another appropriate program,
to be 22-30 nucleotides in length, to have a GC content of 50% or
more, and to anneal to the target sequence at temperatures about
68-72.degree. C. Any stretch of nucleotides which would result in
hairpin structures and primer-primer dimerizations is avoided.
[0185] The original, selected cDNA libraries, or a human genomic
library are used to extend the sequence; the latter is most useful
to obtain 5' upstream regions. If more extension is necessary or
desired, additional sets of primers are designed to further extend
the known region.
[0186] By following the instructions for the XL-PCR kit (Perkin
Elmer) and thoroughly mixing the enzyme and reaction mix, high
fidelity amplification is obtained. Beginning with 40 pmol of each
primer and the recommended concentrations of all other components
of the kit, PCR is performed using the Peltier Thermal Cycler
(PTC200; M.J. Research, Watertown, Mass.) and the following
parameters:
1 Step 1 94.degree. C. for 1 min (initial denaturation) Step 2
65.degree. C. for 1 min Step 3 68.degree. C. for 6 min Step 4
94.degree. C. for 15 sec Step 5 65.degree. C. for 1 min Step 6
68.degree. C. for 7 min Step 7 Repeat step 4-6 for 15 additional
cycles Step 8 94.degree. C. for 15 sec Step 9 65.degree. C. for 1
min Step 10 68.degree. C. for 7:15 min Step 11 Repeat step 8-10 for
12 cycles Step 12 72.degree. C. for 8 min Step 13 4.degree. C. (and
holding)
[0187] A 5-10 .mu.1 aliquot of the reaction mixture is analyzed by
electrophoresis on a low concentration (about 0.6-0.8%) agarose
mini-gel to determine which reactions were successful in extending
the sequence. Bands thought to contain the largest products are
selected and removed from the gel. Further purification involves
using a commercial gel extraction method such as QIAQuick.TM.
(QIAGEN Inc.). After recovery of the DNA, Klenow enzyme is used to
trim single-stranded, nucleotide overhangs creating blunt ends
which facilitate religation and cloning.
[0188] After ethanol precipitation, the products are redissolved in
13 .mu.l of ligation buffer, 1 .mu.l T4-DNA ligase (15 units) and 1
.mu.l T4 polynucleotide kinase are added, and the mixture is
incubated at room temperature for 2-3 hours or overnight at
16.degree. C. Competent E. coli cells (in 40 .mu.l of appropriate
media) are transformed with 3 .mu.l of ligation mixture and
cultured in 80 .mu.l of SOC medium (Sambrook et al., supra). After
incubation for one hour at 37.degree. C., the whole transformation
mixture is plated on Luria Bertani (LB)-agar (Sambrook et al.,
supra) containing 2.times.Carb. The following day, several colonies
are randomly picked from each plate and cultured in 150 .mu.l of
liquid LB/2.times.Carb medium placed in an individual well of an
appropriate, commercially-available, sterile 96-well microtiter
plate. The following day, 5 .mu.l of each overnight culture is
transferred into a non-sterile 96-well plate and after dilution
1:10 with water, 5 .mu.l of each sample is transferred into a PCR
array.
[0189] For PCR amplification, 18 .mu.l of concentrated PCR reaction
mix (3.3x) containing 4 units of rTth DNA polymerase, a vector
primer, and one or both of the gene specific primers used for the
extension reaction are added to each well. Amplification is
performed using the following conditions:
2 Step 1 94.degree. C. for 60 sec Step 2 94.degree. C. for 20 sec
Step 3 55.degree. C. for 30 sec Step 4 72.degree. C. for 90 sec
Step 5 Repeat steps 2-4 for an additional 29 cycles Step 6
72.degree. C. for 180 sec Step 7 4.degree. C. (and holding)
[0190] Aliquots of the PCR reactions are run on agarose gels
together with molecular weight markers. The sizes of the PCR
products are compared to the original partial cDNAs, and
appropriate clones are selected, ligated into plasmid, and
sequenced.
[0191] VI Labeling and Use of Hybridization Probes
[0192] Hybridization probes derived from SEQ ID NO:2 are employed
to screen cDNAs, genomic DNAs, or mRNAs. Although the labeling of
oligonucleotides, consisting of about 20 base-pairs, is
specifically described, essentially the same procedure is used with
larger cDNA fragments. Oligonucleotides are designed using
state-of-the-art software such as OLIGO 4.06 (National
Biosciences), labeled by combining 50 pmol of each oligomer and 250
.mu.Ci of [.gamma.-.sup.32P] adenosine triphosphate (Amersham) and
T4 polynucleotide kinase (DuPont NENO.RTM., Boston, Mass.). The
labeled oligonucleotides are substantially purified with Sephadex
G-25 superfine resin column (Pharmacia & Upjohn). A portion
containing 10.sup.7 counts per minute of each of the sense and
antisense oligonucleotides is used in a typical membrane based
hybridization analysis of human genomic DNA digested with one of
the following endonucleases (Ase I, Bgl II, Eco RI, Pst I, Xba 1,
or Pvu II; DuPont NEN.RTM.).
[0193] The DNA from each digest is fractionated on a 0.7% agarose
gel and transferred to nylon membranes (Nytran Plus, Schleicher
& Schuell, Durham, N.H.). Hybridization is carried out for 16
hours at 40.degree. C. To remove nonspecific signals, blots are
sequentially washed at room temperature under increasingly
stringent conditions up to 0.1.times.1 saline sodium citrate and
0.5% sodium dodecyl sulfate. After XOMAT AR.TM. film (Kodak,
Rochester, N.Y.) is exposed to the blots, or the blots are exposed
in a PhosphorLmager cassette (Molecular Dynamics, Sunnyvale,
Calif.), hybridization patterns are compared visually.
[0194] VII Antisense Molecules
[0195] Antisense molecules to the HSEBP-encoding sequence, or any
part thereof, is used to inhibit in vivo or in vitro expression of
naturally occurring HSEBP. Although use of antisense
oligonucleotides, comprising about 20 base-pairs, is specifically
described, essentially the same procedure is used with larger cDNA
fragments. An oligonucleotide based on the coding sequences of
HSEBP, as shown in FIGS. lA, B, C, is used to inhibit expression of
naturally occurring HSEBP. The complementary oligonucleotide is
designed from the most unique 5' sequence as shown in FIG. 1A and
used either to inhibit transcription by preventing promoter binding
to the upstream nontranslated sequence or translation of an
HSEBP-encoding transcript by preventing the ribosome from binding.
Using an appropriate portion of the signal and 5' sequence of SEQ
ID NO:2, an effective antisense oligonucleotide includes any 15-20
nucleotides spanning the region which translates into the signal or
5' coding sequence of the polypeptide as shown in FIG. 1A.
[0196] VIII Expression of HSEBP
[0197] Expression of HSEBP is accomplished by subcloning the cDNAs
into appropriate vectors and transforming the vectors into host
cells. In this case, the cloning vector, pSport, previously used
for the generation of the cDNA library is used to express HSEBP in
E. coli. Upstream of the cloning site, this vector contains a
promoter for .beta.-galactosidase, followed by sequence containing
the amino-terminal Met, and the subsequent seven residues of
.beta.-galactosidase. Immediately following these eight residues is
a bacteriophage promoter useful for transcription and a linker
containing a number of unique restriction sites.
[0198] Induction of an isolated, transformed bacterial strain with
IPTG using standard methods produces a fusion protein which
consists of the first eight residues of .beta.-galactosidase, about
5 to 15 residues of linker, and the full length protein. The signal
residues direct the secretion of HSEBP into the bacterial growth
media which can be used directly in the following assay for
activity.
[0199] IX Demonstration of HSEBP Activity
[0200] HSEBP can be expressed by transforming a mammalian cell line
such as COS7, HeLa or CHO with an eukaryotic expression vector
encoding HSEBP. Eukaryotic expression vectors are commercially
available and the techniques to introduce them into cells are well
known to those skilled in the art. The cells are incubated for
48-72 hours after transformation under conditions appropriate for
the cell line to allow expression and accumulation of HSEBP.
[0201] A small amount of radioactive [.sup.75Se]-selenite is added
to the culture media 12-24 hours prior to harvesting the cells. The
cells are washed in cold buffer to remove excess selenite, lysed
with detergent, and the solubilized proteins resolved by
SDS-polyacrylamide gel electrophoresis; marker proteins of known
molecular weight (BioRad, Hercules, Calif.) can be electrophoresed
in parallel lanes of the gel and used to calibrate sizes. Following
electrophoresis, the gel is exposed against Kodak X-OMAT AR film
(Kodak, Rochester, N.Y.) for a suitable period of time. A band will
be visible on the film at the position expected for a protein of
the predicted size for HSEBP. A comparison can be made with the
Se-binding proteins present in untransformed cells or with cells
transformed with vector sequences alone.
[0202] X Production of HSEBP Specific Antibodies
[0203] HSEBP that is substantially purified using PAGE
electrophoresis (Sambrook, supra), or other purification
techniques, is used to immunize rabbits and to produce antibodies
using standard protocols. The amino acid sequence deduced from SEQ
ID NO:2 is analyzed using DNASTAR software (DNASTAR Inc) to
determine regions of high immunogenicity and a corresponding
oligopolypeptide is synthesized and used to raise antibodies by
means known to those of skill in the art. Selection of appropriate
epitopes, such as those near the C-terminus or in hydrophilic
regions, is described by Ausubel et al. (supra), and others.
[0204] Typically, the oligopeptides are 15 residues in length,
synthesized using an Applied Biosystems Peptide Synthesizer Model
431A using fmoc-chemistry, and coupled to keyhole limpet hemocyanin
(KLH, Sigma, St. Louis, Mo.) by reaction with
N-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS; Ausubel et al.,
supra). Rabbits are immunized with the oligopeptide-KLH complex in
complete Freund's adjuvant. The resulting antisera are tested for
antipeptide activity, for example, by binding the peptide to
plastic, blocking with 1% BSA, reacting with rabbit antisera,
washing, and reacting with radioiodinated, goat anti-rabbit
IgG.
[0205] XI Purification of Naturally Occurring HSEBP Using Specific
Antibodies
[0206] Naturally occurring or recombinant HSEBP is substantially
purified by immunoaffinity chromatography using antibodies specific
for HSEBP. An immunoaffinity column is constructed by covalently
coupling HSEBP antibody to an activated chromatographic resin, such
as CNBr-activated Sepharose (Pharmacia & Upjohn). After the
coupling, the resin is blocked and washed according to the
manufacturer's instructions.
[0207] Media containing HSEBP is passed over the immunoaffinity
column, and the column is washed under conditions that allow the
preferential absorbance of HSEBP (e.g., high ionic strength buffers
in the presence of detergent). The column is eluted under
conditions that disrupt antibody/HSEBP binding (e.g., a buffer of
pH 2-3 or a high concentration of a chaotrope, such as urea or
thiocyanate ion), and HSEBP is collected.
[0208] XII Identification of Molecules which Interact with
HSEBP
[0209] HSEBP or biologically active fragments thereof are labeled
with [.sup.125I]-Bolton-Hunter reagent (Bolton et al. (1973)
Biochem. J. 133:529). Candidate molecules previously arrayed in the
wells of a multi-well plate are incubated with the labeled HSEBP,
washed and any wells with labeled HSEBP complex are assayed. Data
obtained using different concentrations of HSEBP are used to
calculate values for the number, affinity, and association of HSEBP
with the candidate molecules.
[0210] All publications and patents mentioned in the above
specification are herein incorporated by reference. Various
modifications and variations of the described method and system of
the invention will be apparent to those skilled in the art without
departing from the scope and spirit of the invention. Although the
invention has been described in connection with specific preferred
embodiments, it should be understood that the invention as claimed
should not be unduly limited to such specific embodiments. Indeed,
various modifications of the described modes for carrying out the
invention which are obvious to those skilled in molecular biology
or related fields are intended to be within the scope of the
following claims.
Sequence CWU 1
1
* * * * *