Methods for identifying and using maintenance genes

Abstract

This invention provides methods for discovering maintenance genes and for using maintenance genes. In one embodiment, the expression of at least three maintenance genes are measured and used as reference (or control) for comparing the expression of target genes in two or more biological samples.

Description

BACKGROUND OF THE INVENTION

This application provides methods, compositions for identifying and using maintenance genes. The methods and compositions have extensive practical applications in areas such as drug discovery and diagnostics.

Housekeeping genes, or maintenance genes, are those genes constitutively expressed to maintain cellular function (See, Watson, J. D., N. H. Hopkins, J. W. Roberts, J. A. Steitz, A. M. Weiner, A. M. Molecular Biology of the Gene, Vol. 1, 1965). Previously tens of genes have been reported as putative housekeeping genes. The genes previously reported were identified by conventional methods and the putative housekeeping role of the gene product is an incidental observation (Duhig, T., C. Ruhrberg, O. Mor, M. Fried. The Human Surfeit Locus. Genomics, 52(1) 72-78, 1998; Hampsey, M. Molecular Genetics of the RNA Polymerase II General Transcriptional Machinery. Microbiol. Mol. Biol. Rev. 62(2):465-503, 1998; May, B. K., C. R. Bhasker, T. C. Cox.. Molecular Regulation of 5-Amniolevulinate Synthase Diseases Related to Heme Biosynthesis. Mol. Biol. Med., 7(5):405-421, 1990; Milner, C. M., R. D. Campbell. Genes, Genes and More Genes in the Human Major Histocompatibility Complex. Bioessays, 14(8):565-571, 1992; Rifkind, R. A., P. A. Marks, A. Bank, M. Terada, G. M. Maniatis, F. E. Reuben, E. Fibach. Erythroid Differentiation and the Cell Cycle: Some Implications from Murine Foetal and Erythroleukemic Cells. Ann. Immunol. 127:887-893, 1976; Roberston, H. A. Immediate-Early Genes, Neuronal Plasticity, and Memory. Biochem. Cell Biol., 70(9): 729-737, 1992; Russo-Marie, F. Macrophages and the Glucocorticoids. J Neuroimmunol, 40(2-3):281-286, 1992; Strehler, B. L., M. R. Freeman. Randomness, Redundancy and Repair: Roles and Relevance to Biological Aging. Mech. Aging Dev. 14(1-2) 15-38, 1980; and Yamamoto, T., Y. Matsui, S. Natori, M. Obinata. Cloning of a Housekeeping-Type Gene (MER5) Preferentially Expressed in Murine Erythroleukemia Cells. Gene 80 2:337-343, 1989).

Recently, massive parallel gene expression monitoring methods have been developed to monitor the expression of a large number of genes using nucleic acid array technology which was described in detail in, for example, U.S. Pat. Nos. 5,871,928, 5,800,992 and 6,040,138; de Saizieu, et al., 1998, Bacteria Transcript Imaging by Hybridization of total RNA to Oligonucleotide Arrays, NATURE BIOTECHNOLOGY, 16:45-48; Wodicka et al., 1997, Genome-wide Expression Monitoring in Saccharomyces cerevisiae, NATURE BIOTECHNOLOGY 15:1359-1367; Lockhart et al., 1996, Expression Monitoring by Hybridization to High Density Oligonucleotide Arrays. NATURE BIOTECHNOLOGY 14:1675-1680; Lander, 1999, Array of Hope, NATURE-GENETICS, 21(suppl.), at 3.

SUMMARY OF THE INVENTION

In one aspect of the current invention, methods for identifying a gene are provided. The methods include the steps of determining the expression of at least one hundred genes in at least two different types of tissues in two different developmental stages; and indicating a gene that is expressed at the same level in the tissues in the stages as the maintenance gene. In some embodiments, the method involves determining the expression of one thousand genes. In some preferred embodiments, the expression of candidate maintenance genes are measured in at least five different types of tissues. In one preferred embodiment, gene expression is determined using nucleic acid probe arrays such as high density oligonucleotide probe arrays, optical fiber arrays, spotted arrays (oligonucleotide, cDNA clones, cDNA fragments, etc.).

In preferred embodiments, a gene is considered as expressed at the same level if the variation of its expression is within 2, 5 or 10 fold. In another preferred embodiment, a gene is considered as expressed at the same level if the variation of its expression is not statistically significant.

In another aspect of the invention, methods are provided for comparing the expression of a gene in a plurality of biological samples. The methods include measuring the expression of at least three, five, seven or ten maintenance genes selected from the group of genes listed in table I or subset of the genes from table 1. The methods further include a step of evaluating the expression of the gene in the plurality of samples using the expression of the at least three, five or ten, maintenance genes. In some embodiments, the expression of a gene is adjusted using the expression of maintenance genes as a control. For example, the expression measurement of a target gene may be divided by the expression measurements of maintenance genes.

DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the invention. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention.

Methods for Gene Expression Monitoring:

Various techniques for large scale polymer synthesis and probe array manufacturing are known. Some examples include the U.S. Pat. Nos.: 5,143,854, 5,242,979, 5,252,743, 5,324,663, 5,384, 261, 5,405,783, 5,412,087, 5,424,186, 5,445,934, 5,451,683, 5,482,867, 5,489,678, 5,491,074, 5,510,270, 5,527,681, 5,550,215, 5,571,639, 5,593,839, 5,599,695, 5,624,711, 5,631,734, 5,677,195, 5,744,101, 5,744,305, 5,753,788, 5,770,456, 5,831,070, and 5,856,011, all of which are incorporated by reference in their entirety for all purposes.

The hybridization conditions between probe and target should be selected such that the specific recognition interaction, i.e., hybridization, of the two molecules, is both sufficiently specific and sufficiently stable. See, e.g., Hames and Higgins (1985) Nucleic Acid Hybridisation: A Practical Approach, IRL Press, Oxford. These conditions will be dependent both on the specific sequence and often on the guanine and cytosine (GC) content of the complementary hybrid strands. The conditions may often be selected to be universally equally stable independent of the specific sequences involved. This typically will make use of a reagent such as an alkylammonium buffer. See, Wood et al. (1985) “Base Composition-independent Hybridization in Tetramethylammonium Chloride: A Method for Oligonucleotide Screening of Highly Complex Gene Libraries,” Proc. Natl. Acad. Sci. USA, 82:1585-1588; and Krupov et al. (1989) “An Oligonucleotide Hybridization Approach to DNA Sequencing,” FEBS Letters, 256:118-122; each of which is hereby incorporated herein by reference. An alkylammonium buffer tends to minimize differences in hybridization rate and stability due to GC content. By virtue of the fact that sequences then hybridize with approximately equal affinity and stability, there is relatively little bias in strength or kinetics of binding for particular sequences. Temperature and salt conditions along with other buffer parameters should be selected such that the kinetics of renaturation should be essentially independent of the specific target subsequence or oligonucleotide probe involved. In order to ensure this, the hybridization reactions will usually be performed in a single incubation of all the substrate matrices together exposed to the identical same target probe solution under the same conditions. The hybridization conditions will usually be selected to be sufficiently specific such that the fidelity of base matching will be properly discriminated. Of course, control hybridizations should be included to determine the stringency and kinetics of hybridization. See for example, U.S. Pat. No. 5,871,928 which is hereby incorporated in its entirety for all purposes. Another factor that can be adjusted to increase the ability of targets to hybridize to probes, is the use of nucleic acid analogs or PNAs in the probes. They can be built into the probes to create a more uniform set of hybridization conditions across the entire array. See U.S. patent application Ser. No. 08/630,427 which is hereby incorporated by reference in its entirety for all purposes.

Samples are then washed and stained using a robotic liquid handling machine such as the GeneChip® Fluidic Station 400 (Affymetrix, Inc., Santa Clara, Calif.). Fluidics stations have been described in, for example, U.S. patent application Ser. Nos. 08/624,133 and 09/070,689. Finally, samples are placed on an automated loader which interfaces with a scanner such as the GeneArray™ scanner (Agilent Technologies). Scanners have been described in, for example, U.S. Pat. Nos. 5,578,832, 5,834,748,and 5,837,832, U.S. patent application Ser. Nos. 08/456,598, 09/238,131, 08/856,642 (now allowed), 09/295,214, 08/456,782, 08/999,188, U.S. Provisional Patent Application No. 60/106,397 and European Patent No. 97925605 each of which is hereby incorporated by reference in its entirety for all purposes.

The results are then analyzed using a computer program. Computer programs for the analysis of hybridization patterns on arrays have been described in, for example, U.S. Pat. Nos. 5,733,729, and 5,795,716, U.S. patent application Ser. Nos. 09/309,328, 09/020,743, 08/531,137, 09/158,765, 08/584,754, 09/049,805, 08/828,952, 08/948,896 and U.S. Provisional Patent Application Nos. 60/033,053 and 60/085,118 each of which is incorporated by reference in its entirety for all purposes.

Methods for Detecting Maintenance Genes:

The term housekeeping gene was broadly defined as a gene that is constitutively expressed. In this application, housekeeping genes are also referred to as maintenance genes. Generally, the housekeeping genes are critical to the processes that must be carried out for successful completion of the cell cycle and consequently play a key role in the activity and maintenance of every cell. It is likely that many genes may be constitutively expressed but in varying amounts in different tissues. These differences in level of abundance are probably more relevant to the characteristic function of each tissue than to the housekeeping/maintenance role.

Until recently the technical challenge of accurately measuring small differences in gene expression have been practically insurmountable, consequently there is little evidence to support the importance of small differences. One aspect of the invention provides methods, compositions, devices and algorithms for detecting Maintenance genes. The method comprises the step of measuring the expression of at least 50 genes, preferably 100 genes, more preferably more than 1000 genes, in a variety of tissues. The method further comprises the step of indicating that the gene is a Maintenance gene if the expression is the same in all the tissues of interest or in a subset of the tissues of interest. The term tissue, as used herein, is intended to describe a biological material from an organism. Therefore, an organ (or a homogenate of the organ), such the liver or kidney, may be referred to as a tissue. The methods are most suitable for simultaneously detecting a large number Maintenance genes. When it is used for simultaneous determination of a large number of Maintenance genes, the method includes the step of simultaneous monitoring of the expression of a large number of genes. Methods for monitoring a large number of genes are well known in the art and are described, for example, in the background section, supra. In some embodiments, the expression of a gene in a number of tissue is measured. The gene is considered as expressed at the same level if it is expressed in all the tissues at levels within ten folds, preferably within fourfold and more preferably within two fold. In some embodiments, a gene is considered as expressed at the same level if it is expressed in all tissues with no statistically difference. In the example that follows, genes were considered as expressed at the same level if they were expressed in all seven tissues at levels within fourfold. For most genes differences less than fourfold are probably not biologically significant but there is not enough data to conclude that a five or six-fold difference is more biologically significant than a three or four-fold difference (Cho, R. J., M. J. Campbell, E. A. Winzeler, L. Steinmetz, A. Conway, L. Wodicka, T. G. Wolfsberg, A. E. Gabrielian, D. Landsman, D. J. Lockhart, R. W. Davis. A Genome-Wide Transcriptional Analysis of the Miotic Cell Cycle. Molecular Cell, 2: 65-73, 1998; Creanor, J., J. M. Mitchinson. Nucleoside Diphosphokinase, An Enzyme With Step Changes in Activity During the Cell Cycle of the Fission Yeast Schizosaccharomyces Pombe. Journal of Cell Science 207-215, 1986; Klevecz, R. R.. The Scientist 22-24, 1999; Klevecz, R. R., S. A. Kaufman, R. M. Shymko, Cellular Clocks and Oscillators. International Review of Cytology, 86:97-128, 1984). For a subset of genes it is likely that small differences have biological relevance such as the genes encoding proteins that function differently when bound to high affinity versus low affinity receptors or gene products triggering cellular cascades (Merchav, S.. The Haematopoietic Effects of Growth Hormone and Insulin-Like Growth Factor-I. J. Pediatr. Endocrin. Metab. 11(6):677-685, 1998; Skerry, T. M. Identification of Novel Signaling Pathways During Functional Adaptation of the Skeleton to Mechanical Loading: The Role of Glutamate as a Paracrine Signaling Agent in the Skeleton. J. Bone Miner Metab. 17(1): 66-70, 1999).

Maintenance Genes:

In another aspect of the invention, a subset of genes expressed at the same level in each of seven major tissues are identified as housekeeping genes (See, Table 1). Most of these genes have never before been specifically identified as belonging in this category. This information is useful for establishing average normal expression levels and will be useful as a reference in studies of normal expression variation (i.e. www.HuGEindex.org.). In one aspect of the invention, the maintenance genes described are used to establish average normal expression levels. In some embodiments, the expression of at least one of the genes listed in table 1, preferably at least two of the genes listed in table 1, more preferably at least 10 of the genes listed in table 1, and even more preferably at least 100 of the genes listed in table 1 is monitored along with the expression of a target gene (gene of interest). The change of the level of expression of the target gene will be evaluated using the expression of the maintenance gene(s) as a control.

Example Identification of Maintenance Genes

Methods

Sample Preparation

All samples were prepared from pools of human adult poly(A) RNA purchased from Clontech (Palo Alto, Calif.). The tissues screened are listed followed by the number of tissues pooled and the Clontech catalog number in parenthesis. Heart, 3 (6533-1), brain, 5 (6516-1), lung, 5 (6524-1), kidney, 8 (6538-1), pancreas, 10 (6539-1), uterus, 10 (6537-1), testis, 19 (6535-1). Poly(A) RNA was amplified and labeled with biotin following the procedure described by Wodicka et al., 1997⁽³²⁾. First strand cDNA synthesis was carried out at 37° C. for 60 minutes. The amplified cRNA (target) was purified on an affinity resin (RNeasy, Qiagen) and quantitated.

Fragmentation, Array Hybridization and Scanning

Labeled target was fragmented by incubation at 94° C. for 35 minutes in the presence of 40 mM Tris-acetate pH 8.1, 100 mM potassium acetate, and 30 mM magnesium acetate. The hybridization solution consisted of 20 ug fragmented cRNA, 0.1 mg/ml sonicated herring sperm DNA in buffer containing 100 mM MES, 1 m[Na⁺], 20 mMEDTA, 0.01% Tween 20 (MES). The hybridization mixture was heated to 99° C. for 5 min. followed by incubation at 45° C. for 5 min. before injection of the sample into the probe array cartridge. All hybridizations were performed in duplicate and were carried out at 45° C. for 16-17 hr with mixing on a rotisserie at 60 rpm. Following hybridization, the solutions were removed, arrays were rinsed with 1×MES (100 mM MES, 1 m[Na⁺], 20 mMEDTA, 0.01% Tween 20). Subsequent washing and staining of the arrays was carried out using the GeneChip® fluidics station protocol EukGE_WS2. The EukGE_WS2 protocol included two post hybridization washes, staining, and a post stain wash. The first wash consisted of 10 cycles of 2 mixes per cycle with Non Stringent Wash Buffer (6×SSPE, 0.01% Tween 20, 0.005% Antifoam) at 25° C. The second wash consisted of 4 cycles of 15 mixes per cycle with Stringent Wash Buffer (100 mm MES, 0.1M [Na⁺], 0.01% Tween 20) at 50° C. The probe arrays were stained for 10 minutes in streptavidin-phycoerythrin solution (SAPE) (1×MES solution, 0.005% antifoam, 10 μg/ml SAPE (Molecular Probes, Eugene, OR) 2 μg/μl acetylated BSA (Sigma, St. Louis, Mo.) at 25° C. The post stain wash consisted of 10 cycles of 4 mixes per cycle at 25° C. The probe arrays were treated for 10 minutes in antibody solution (1×MES solution, 0.005% antifoam, 2 μg/μl acetylated BSA, 0.1 μg/μl normal goat IgG (Sigma Chemical, St. Louis Mo.), 3 μg/μl antibody (goat), antistreptavidin, biotinylated (Vector Laboratories, Burlingame, Calif.) at 25° C. The final wash consisted of 15 cycles of 4 mixes per cycle at 30° C. Following washing and staining, probe arrays were scanned 2 times (multiple image scan) at 3 μm resolution using the GeneChip® System confocal scanner made for Affymetrix Inc. by Hewlett Packard.

Probe Arrays

The arrays were synthesized using light-directed combinatorial chemistry as described previously. The Hu6.8K_all GeneChip® probe arrays used for the current study contain probe sets representing 7129 genes. The oligonucleotides are 25 bases in length. Probes are complementary and correspond to human genes registered in Unigene, GenBank and The Institute for Genomic Research Database (TIGR). Each probe set has oligonucleotides that are identical to sequence in the gene and oligonucleotides that contain a homomeric (base transversion) mismatch at the central base position of the oligomer used for measuring cross hybridization. Probes are selected with a bias toward the 3′ region of each gene. Probe pairs representing human genes such as GAPDH, B-actin, transferrin receptor and transcription factor ISGF-3 serve as internal controls for monitoring RNA integrity. In addition, the probe arrays contain oligonucleotides representing sequences of bacterial genes, BioB, BioC, BioD, and one phage gene, Cre, as quantitative standards. Copy numbers are determined by correlating the known concentrations of the spiked standards with their hybridization. Copies per cell are calculated based on the assumption that the average transcript length is 1 kb and there are 300,000 transcripts per cell.

Analysis

All samples were hybridized in duplicate and only those transcripts detected as present in duplicate hybridizations or absent in duplicate hybridizations are reported. Of the transcripts present in duplicate hybridizations the hybridization values were within two fold. The values from the duplicate hybridizations were averaged. GeneChip® 3.0 software was used to scan and analyze the data. Microsoft Excel and Microsoft Access were also used for data analysis.

Result

Using GeneChip® probe arrays (Affymetrix, Santa Clara, Calif.), 695 genes that are expressed in common among heart, brain, lung, kidney, pancreas, uterus and testis were identified. 241 of the genes were detected at similar levels in each of the tissues; 44 genes were detected at low abundance, 72 detected at low-moderate abundance, 100 at moderate abundance, 13 at moderate-high abundance, and 12 at high abundance (See Table 1).

TABLE 1
Maintenance genes sorted by function. Abundance levels are
binned by copies per cell where low, L, <5, low-moderate,
LM > 5 < 10, moderate, M, > 10 < 50, moderate-high,
MH, > 50 < 100, high, H, >100.
Accession		Abun-
Number	Description	dance
ATPase
M37104	mitochondrial ATPase coupling	M
	factor 6 subunit (ATP5A)
U51478	sodium/potassium-transporting	M
	ATPase beta-3 subunit
Z71460	vacuolar-type H(+)-ATPase	LM
	115 kDa subunit
Channels, pores
D31846	aquaporin-2 water channel	M
L08666	porin (por)	M
Cytochrome
AC002115	COX6B (COXG) on chromosome 19	M
	cosmids
M22760	nuclear-encoded mitochondrial	M
	cytochrome c oxidase Va subunit
L32977	ubiquinol cytochrome c reductase	M
	Rieske iron-sulphur protein
X13238	cytochrome c oxidase subunit VIc	M
X16560	COX VIIc subunit VIIc of	M
	cytochrome c oxidase
M28713	NADH-cytochrome b5 reductase (b5R)	LM
Dehydrogenase
D90086	pyruvate dehydrogenase	M
	(EC 1.2.4.1) beta subunit
D43682	very-long-chain acyl-CoA	M
	dehydrogenase (VLCAD)
U17886	succinate dehydrogenase	LM
	iron-protein subunit (sdhB)
U05861	hepatic dihydrodiol dehydrogenase	L
L13761	dihydrolipoamide dehydrogenase	L
DNA binding
J03827	Y box binding protein-1 (YB-1)	MH
M26730	mitochondrial ubiquinone-binding	M
	protein with an LTR-like sequence
X75593	rab 13	M
U79528	SR31747 binding protein 1	M
L37368	RNA-binding protein	M
U33821	tax1-binding protein TXBP151	M
Z29505	nucleic acid binding protein sub2.3	M
U07857	18 kDa Alu RNA binding protein,	M
M94556	mitochondrial specific single	LM
	stranded DNA binding protein N31
M28209	GTP-binding protein (RAB1)	LM
D13988	rab GDI	LM
U51334	putative RNA binding protein (RBP56),	LM
D43951	KIAA0099, (pumilio-like, putative	LM
	DNA binding)
U65928	Jun activation domain binding	L
	protein
Electron transfer
X71129	electron transfer flavoprotein	LM
	beta subunit
J04058	electron transfer flavoprotein	L
	alpha-subunit
G protein related
U20285	Gps1 (GPS1)	M
U45982	G protein-coupled receptor GPR-9-6	LM
U31384	G protein gamma-11 subunit	LM
X81625	Cl1 protein	L
HLA
D32129	HLA class-I (HLA-A26) heavy chain	M
X03100	HLA-SB alpha (class II antigen)	M
X75091	HLA-DR associated protein II	L
	(PHAPII)
Heat shock
J04988	90 kD heat shock protein	MH
L15189	mitochondrial HSP75	LM
Histone
M11353	H3.3 histone class C	MH
U50079	histone deacetylase HD1	LM
X05855	histone H3.3	L
Interferons
X57351	1-8D from interferon-inducible	H
	family
X59892	IFN-inducible gamma-2 protein	M
J00212	leukocyte interferon (ifn-alpha)	L
	alpha-f
Kinase
M14676	src-like kinase (slk)	M
L08835	DM kinase (myotonic dystrophy	M
	kinase)
M30448	casein kinase II beta subunit	LM
Lysosome associated
AJ000099	lysosomal hyaluronidase	M
U91932	AP-3 complex sigma3A subunit	M
M15182	beta-glucuronidase (lysosomal	LM
	enzyme)
M29877	alpha-L-fucosidase, (lysosomal	LM
	enzyme)
Membrane
D29963	SFA-1, a member of transmembrane 4	M
	superfamily
L10284	IP90, integral membrane protein,	M
	calnexin
U57877	nuclear-encoded mitochondrial	LM
	integral membrane protein CII-3
Metabolism
D78361	ornithine decarboxylase antizyme	H
M33764	ornithine decarboxylase amino acid	M
	metabolism
HG2279-	Triosephosphate Isomerase	M
HT2375
U86070	phosphomannomutase (carbohydrate	LM
	metabolism)
U32114	caveolin-2 (lipid metabolism)	L
Mitochondrial associated
Z70759	mitochondrial 16S rRNA	H
M22538	nuclear-encoded mitochondrial	M
	NADH-ubiquinone reductase 24 kD
	subunit
M22760	nuclear-encoded mitochondrial	M
	cytochrome c oxidase Va subunit
X60036	mitochondrial phosphate carrier	M
	protein
M37104	mitochondrial ATPase coupling	M
	factor 6 subunit (ATP5A)
M26730	mitochondrial ubiquinone-binding	M
	protein with an LTR-like sequence
X99728	NDUFV3, mitochondrial NADH	M
	ubiquinone oxidoreductase
U59309	nuclear-encoded mitochondrial	LM
	fumarase precursor (FH)
L15189	mitochondrial HSP75	LM
M94556	mitochondrial specific single	LM
	stranded DNA binding protein
U57877	nuclear-encoded mitochondrial	LM
	integral membrane protein CII-3
L07033	hydroxymethylglutaryl-CoA lyase	LM
U15174	Nip3 (NIP3) (mitochondrial,	L
	pro-apoptotic protein family)
Phosphatase
U45975	phosphatidylinositol (4,5)	M
	bisphosphate 5-phosphatase homolog
X74008	phosphatase 1 gamma	LM
X81003	HCG V (phosphatase inhibitor)	LM
M65254	phosphatase 2A 65 kDa regulatory	L
	subunit-beta
Polymerase
Z27113	RNA polymerase II subunit 14.4 kD	M
U37690	RNA polymerase II subunit (hsRPB10)	M
Z47727	RNA polymerase II subunit	LM
Protease, proteinase related
L02426	26S protease (S4) regulatory subunit	M
M23254	Ca2-activated neutral protease	M
	large subunit (CANP)
X12451	pro-cathepsin L (major excreted	M
	protein MEP)
S69272	cytoplasmic antiproteinase, 38 kD	M
	intracellular serine proteinase
	inhibitor
Proteasome
D29012	proteasome subunit Y	M
D26598	proteasome subunit HsC10-II	M
D26599	proteasome subunit HsC7-I	M
D38047	26S proteasome subunit p31	M
AB003177	proteasome subunit p27	LM
D00763	proteasome subunit HC9	LM
D50063	proteasome subunit p40_/Mov34	LM
	protein,
X61970	macropain subunit zeta (proteasome)	LM
X95586	MB1	LM
D00760	proteasome subunit HC3	L
D00762	proteasome subunit HC8	L
Receptor and receptor associated proteins
M63959	alpha-2-macroglobulin receptor-	M
	associated protein
D23673	insulin receptor substrate-1-like	M
	(IRS-1)
X07979	fibronectin receptor beta subunit	M
U83239	CC chemokine STCP-1 (immune	M
	function, T-receptor assoc)
M88279	immunophilin (FKBP52)	M
U45982	G protein-coupled receptor GPR-9-6	LM
X56253	MPR46 46 kd mannose 6-phosphate	LM
	receptor
X80763	5-HT2c receptor	LM
L40357	thyroid receptor interactor (TRIP7)	L
Reductase
M22538	nuclear-encoded mitochondrial	M
	NADH-ubiquinone reductase 24 kD
	subunit
X91247	thioredoxin reductase	LM
X15414	aldose reductase (EC 1.1.1.2)	LM
M28713	NADH-cytochrome b5 reductase (b5R)	LM
Repair
U07418	DNA mismatch repair (hmlh1)	L
U49785	D-dopachrome tautomerase	LM
Replication
J05249	replication protein A 32-kD subunit	LM
Ribonucleoprotein
HG3076-	heterogeneous nuclear	M
HT3238	ribonucleoprotein K, alt. splice 1
X16135	novel heterogeneous nuclear	M
	RNP protein, L protein
X78136	hnRNP-E2	M
M94630	hnRNP-C like protein	M
M16342	nuclear ribonucleoprotein	LM
	particle (hnRNP) C protein
Z23064	hnRNP G protein	L
Ribosomal
X81625	ribosomal protein L37a (RPL37A)	H
Z12962	homologue to yeast ribosomal	H
	protein L41
HG3214-	Metallopanstimulin, MPS-1 (S27	H
HT3391	Zinc finger)
HG1800-	ribosomal protein S20	H
HT1823
U14973	ribosomal protein S29	H
Z26876	ribosomal protein L38	MH
M77232	ribosomal protein S6	MH
HG821-	ribosomal protein S13	MH
HT821
M13934	RPS14, ribosomal protein S14	MH
Ribosylation
M84332	ADP-ribosylation factor 1	M
M36341	ADP-ribosylation factor 4 (ARF4)	LM
Signal transduction
D49396	Apol (MER5-like protein)	L
Structure
U57341	neurofilament triplet L protein	MH
Z19554	vimentin	MH
X51521	ezrin	M
HG2238-	nuclear mitotic apparatus protein	M
HT2321	1, alt. splice form 2
M64571	microtubule-associated protein 4	M
M31013	nonmuscle myosin heavy chain (NMHC)	M
V00599	fragment encoding beta-tubulin	M
	(D-beta-1)
U24105	coatomer protein (HEPCOP),	M
M95627	angio-associated migratory cell	LM
	protein (AAMP)
D38549	KIAA0068	LM
U56637	capping protein alpha subunit	LM
	isoform 1
X72964	caltractin	LM
X70476	subunit of coatomer complex	LM
D28915	hepatitis C-associated microtubular	L
	aggregate protein p44
X82103	beta-COP	L
Synthases and synthetases
D14710	ATP synthase alpha subunit	MH
X76013	QRSHs, glutaminyl-tRNA synthetase	M
X83218	ATP synthase	M
X60221	H+-ATP synthase subunit b	M
D31890	KIAA0070	M
U09510	glycyl-tRNA synthetase	LM
U79262	deoxyhypusine synthase	LM
J03473	poly(ADP-ribose) synthetase	LM
X94754	yeast methionyl-tRNA synthetase	LM
	homologue
Transcription
L49380	transcription factor ZFM1	M
U95040	transcriptional corepressor	M
	hKAP1/TIF1B
U10323	nuclear factor NF45	M
L12168	adenylyl cyclase-associated	M
	protein (CAP),
M97935	transcription factor ISGF-3	LM
	sequence
X52882	t-complex polypeptide 1	LM
L19067	NF-kappa-B transcription factor	L
	p65 subunit
D63478	KIAA0144	L
U15782	cleavage stimulation factor 77 kDa	L
	subunit (polyadenylation)
L20298	transcription factor (CBFB)	L
Transferase
U56417	lysophosphatidic acid	M
	acyltransferase-alpha
U62739	branched-chain amino acid	M
	aminotransferase (ECA40)
Y08200	rab geranylgeranyl transferase,	M
	alpha-subunit
U82010	heme A: farnesyltransferase (COX10)	LM
U86529	glutathione transferase Zeta 1	LM
	(GSTZ1)
D26535	dihydrolipoamide	L
	succinyltransferase
Transformation related
U50523	BRCA2 region	M
U57342	myelodysplasia/myeloid leukemia	M
	factor 2 (MLF2),
HG4541-	transformation-related protein	M
HT4946
M15990	c-yes-1	L
L12535	RSU-1/RSP-1 (Ras suppressor)	L
Translation, inititiation and elongation
J04617	elongation factor EF-1-alpha	H
X51466	elongation factor 2	MH
L26247	sui 1, N278 iso1	MH
U46025	translation initiation factor	M
	eIF-3 p110 subunit
X55733	initiation factor 4B	LM
X98743	RNA helicase (Myc-regulated	L
	dead box protein)
Transport
U36341	SLC6A8 (creatine transporter)	M
U51478	sodium/potassium-transporting	M
	ATPase beta-3 subunit
X81817	BAP31 (ER, protein sorting)	M
Y00281	ribophorin I (ER)	M
Y00282	ribophorin II (ER)	M
U70660	copper transport protein HAH1	LM
U41740	trans-Golgi p230	LM
X12791	signal recognition particle,	L
	SRP 19 kD protein (ER)
Ubiquitin related
X56997	UbA52 coding for ubiquitin-52	MH
	amino acid fusion protein
M26880	ubiquitin	M
U46751	phosphotyrosine independent	M
	ligand p62 for the Lck SH2 domain
U39317	E2 ubiquitin conjugating enzyme	L
	UbcH5B (UBCH5B),
Zinc finger
HG3214-	Metallopanstimulin, MPS-1 (S27,	H
HT3391	Zinc finger)
X70394	OZF	L
U09412	zinc finger protein ZNF134	L
HG3454-	zinc finger protein 20	L
HT3647
Undefined
X67698	unknown product	M
L11066	unknown product	M
U79294	unknown product	M
D28124	unknown product	M
D21261	KIAA0120	M
D87451	KIAA0262	M
D14694	KIAA0024	M
ISGF3A/	unknown product	LM
M97935
L20773	unknown product	LM
D42043	KIAA0084	LM
D50911	KIAA0121	LM
D79994	KIAA0172	LM
D29643	KIAA0115	LM
D14662	KIAA0106	LM
D86963	KIAA0208	LM
D21853	KIAA0111	LM
D63476	KIAA0142	LM
D42087	KIAA0118	L
D30756	KIAA0049	L
D80004	KIAA0182	L
D79993	KIAA0171	L
L40395	unknown product	L
Others
X98482	TNNT2, (troponin)	H
U06155	chromosome 1 q subtelomeric	H
	sequence
M33680	26-kDa cell surface protein TAPA-1	H
M13450	esterase D	M
U11861	G10 homolog, edg-2	M
U62317	hypothetical protein 384D8_2	M
	on chromosome 22q13 (other)
HG3991-	Cpg-enriched DNA (other)	M
HT4261
X80199	MLN51	M
X80200	MLN62	M
U46570	tetratricopeptide repeat protein	M
	(tpr1) N297 (other)
HG3597-	major histocompatibility complex,	M
HT3800	class I
X71428	fus (nuclear RNA binding protein)	M
U73824	p97	M
Y00433	glutathione peroxidase (peroxide	M
	clearance)
U02493	54 kDa protein	M
U88964	HEM45	LM
D78129	squalene epoxidase (sterol	LM
	biosynthesis)
D43951	KIAA0099, (pumilio-like, putative	LM
	DNA binding)
X96484	DGCR6 protein (organization,	LM
	migration during development)
HG1155-	colony-stimulating factor 1,	LM
HT4822	macrophage, alt. splice 3
L38932	GT197 N305	LM
X66397	tpr	LM
L42572	p87/89 (ER transmembrane protein)	LM
X80695	OXA1Hs (cytochrome oxidase assembly)	LM
Y00097	p68 (membrane associated, calcium	LM
	binding protein)
Z48042	GPI-anchored protein p137	LM
Z35093	SURF-1 (Surfeit gene family,	LM
	biogenesis of cytochrome C oxidase)
U54644	tub homolog	LM
Z93784	mouse brain protein E46-like	L
	sequence
L38616	brain and reproductive organ-	L
	expressed protein (BRE)
D63506	unc-18 homologue	L
U18009	human gene on chromosome 17q21	L
L27476	X104 (membrane associated,	L
	kinase containing protein family)
M73720	mast cell carboxypeptidase A	L
	(MC-CPA)

For example, no difference in expression level was detected for 5 of the genes and a two-fold difference was detected for 46 of the genes. 454 genes are expressed in all seven tissues but vary in expression level by more than fourfold. 333 of the genes vary in expression level by 5-10 fold. Included in this subset are genes frequently used as controls in standard expression analysis including beta actin (M10277) varying by 7-fold with highest expression in brain and uterus and lowest expression in heart, and GAPDH (M33197) varying by 8-fold with highest expression in brain, heart and kidney and lowest in pancreas. Another form of beta actin (X00351) varied by 22-fold with highest expression in uterus and lowest in pancreas. Alpha actin (X13839) varied by 23-fold and gamma actin (M19283) by 9-fold. 40 genes expressed in all seven tissues differ in transcript levels by greater than 19 fold and of these eight differ by more than 50-fold, including COX7A muscle isoform (M83186) varying by 52-fold, highest in heart, lowest in kidney, pancreas and testis, lectin (J04456) varying by 58-fold, highest in uterus, lowest in kidney and pancreas, myosin heavy chain (AF001548) varying by 61-fold, highest in uterus, lowest in brain and pancreas, elongation factor-1 delta (Z21507) varying by 69-fold, highest in pancreas, lowest in lung and kidney, RNA polymerase II elongation protein (Z47087) varying by 70-fold, highest in brain, lowest in pancreas, extracellular mRNA for glutathione peroxidase (D00632) varying by 78-fold, highest in kidney, lowest in brain, pancreas and testis, 14-9-9 protein eta chain (D78577) varying by 81-fold, highest in brain, lowest in testis, and L-arginie:glycine amidinotransferase (S68805) varying by 133-fold, highest in pancreas and lowest in heart and lung.

In the same experiments, genes expressed uniquely in each of the seven tissues were also identified (Table II). For instance, in heart there were 4 transcripts not detected in the other 6 tissues; muscle glycogen synthase (J04501), NADH oxidoreductase subunit (L04490), MLC-1V/Sb isoform (M24248) and cytokine inducible nuclear protein (X83703). Twenty nine uniquely expressed transcripts were identified in the kidney including many that are expected such as potassium channel ROM-K3 (U65406) and renal Na/Pi cotransporter (L13258) as well as genes of unknown function such as a gene that maps to chromosome 19 (U95090). 45 uniquely expressed transcripts were detected in uterus, 28 in pancreas and 19 in lung. Not surprisingly, the greatest number of uniquely expressed genes, 91 and 94 respectively, were found in brain and testis.

TABLE II
Genes Uniquely Expressed in a Comparison
of Eleven Human Tissues
Accession
No.	Description	Bin*
Uniquely Expressed in Adult Heart
J04501	Muscle glycogen synthase	M
M24248	MLC-1V/Sb isoform	M
X83703	Cytokine inducible nuclear protein	LM
Uniquely Expressed in Fetal Kidney
D88532	P55pik	L
M26901	Renin	M
M81829	Somatostatin receptor isoform 1	L
U19107	ZNF127	L
U19906	Arginine vasopressin receptor 1 (AVPR1)	L
U34301	Nonmuscle myosin heavy chain IIB	LM
X58431	HOX 2.2	M
Z67743	CLC-7 chloride channel protein	LM
Uniquely Expressed in Fetal Liver
AF000573	Homogentisate 1,2-dioxygenase	LM
D00097	Amyloid P component (SAP)	M
D16611	Coproporphyrinogen oxidase	M
D16626	Histidase	M
D21063	KIAA0030	M
D26361	KIAA0042	L
D38535	PK-120	H
D38537	Protoporphyrinogen oxidase	M
D42055	KIAA0093	L
D49357	S-adenosylmethionine synthetase	LM
D49742	HGF activator like protein	M
D79988	KIAA0166	L
D84454	UDP-galactose translocator	LM
D87116	MAP kinase kinase 3b	M
D90282	Carbamyl phosphate synthetase I	MH
	(EC 6.3.4.16)
HG1148-	Lipopolysaccharide-Binding Protein	H
HT1148
HG1227-	Collagen, Type II, Alpha 1	M
HT1227
HG1649-	Elastase 1	M
HT1652
HG2730-	Fibrinogen, A Alpha Polypeptide,	H
HT2827	Alt. Splice 2, E
HG3105-	Atpase, Cu2+ Transporting	L
HT3281
HG3565-	Zinc Finger Protein	M
HT3768
HG627-	Rhesus (Rh) Blood Group System	MH
HT5097	Ce-Antigen, Alt. Splice 2, Rhvi
J00116	Collagen COL2A1	M
J02982	Glycophorin B	MH
J03474	Serum amyloid A	H
J03626	UMPS	L
J05070	Type IV collagenase	L
J05500	Beta-spectrin (SPTB)	M
K01383	Metallothionein-I-A	MH
K02402	Coagulation factor IX	M
L00190	Antithrombin III (ATAIII)	H
L01664	Eosinophil Charcot-Leyden crystal	L
	(CLC) protein (lysophospholipase)
L06133	Putative Cu++-transporting	L
	P-type ATPase
L09708	Complement component 2 (C2), allele b	MH
L11244	C4b-binding protein beta-chain	M
L31860	Glycophorin A, MN-types (GYPA)	M
L32140	Afamin	M
L34081	Bile acid CoA: Amino acid	LM
	N-acyltransferase
L48516	Paraoxonase 3 (PON3)	M
L76571	Nuclear hormone receptor (shp)	M
L77567	Mitochondrial citrate transport	M
	protein (CTP)
M10014	Fibrinogen gamma chain and gamma-	H
	prime chain
M10058	Asialoglycoprotein receptor H1	M
M10950	Alpha-fetoprotein (AFP)	M
M11025	Asialoglycoprotein receptor H2	M
M11567	Angiogenin and three Alu repetitive	M
	sequences
M13699	Ceruloplasmin (ferroxidase)	MH
M14091	Thyroxine-binding globulin	M
M15205	Thymidine kinase with clustered	M
	Alu repeats in the introns
M16961	Alpha-2-HS-glycoprotein alpha and	H
	beta chain
M16967	Coagulation factor V	M
M16973	Complement protein C8 beta subunit	M
M17262	Prothrombin (F2) gene, and Alu and	H
	KpnI repeats
M19481	Follistatin	LM
M19828	Apolipoprotein B-100 (apoB)	H
M20786	Alpha-2-plasmin inhibitor	MH
M22638	LYL-1 protein	M
M22898	Phosphoprotein p53	L
M27819	Anion exchange protein 1 (AE1, band 3)	MH
M29194	Triglyceride lipase	M
M36803	Hemopexin	H
M58569	Fibrinogen alpha-subunit bipartite	H
	transcript of extended (alpha-E)
	variant
M58600	Heparin cofactor II (HCF2), exons 1	H
	through 5
M59820	Granulocyte colony-stimulating	LM
	factor receptor (CSF3R)
M60298	Erythrocyte membrane protein band 4.2	MH
	(EPB42)
M61827	Leukosialin (CD43)	LM
M61855	Cytochrome P4502C9 (CYP2C9), clone 25	L
M64554	F13A1 gene (coagulation factor XIIIb)	M
M68895	Alcohol dehydrogenase 6	L
M71243	Glycophorin Sta (type A) exons 3 and 4	MH
M75106	Prepro-plasma carboxypeptidase B	MH
M86873	Type A plasminogen related	M
S42457	Photoreceptor cGMP-gated channel	L
S48983	SAA4, serum amyloid A	M
S70004	Glycogen synthase	LM
S72370	Pyruvate carboxylase	LM
S77393	Transcript ch138	LM
S77763	Nuclear factor erythroid 2	M
S77893	Glycophorin SAT	MH
S78234	Nuc2 homolog	LM
U00001	Homologue of S. pombe nuc2+	L
	and A. nidulans bimA
U01317	Epsilon-globin	LM
U05255	Glycophorin HeP2	H
U08006	Complement 8 alpha subunit (C8A)	M
U12778	Acyl-CoA dehydrogenase	LM
U13061	Dehydroepiandrosterone	L
	sulfotransferase (STD)
U14518	Centromere protein-A (CENP-A)	L
U18919	Clone pOV-2	L
U20530	Bone phosphoprotein spp-24 precursor	M
U20979	Chromatin assembly factor-I	L
	p150 subunit
U32989	Tryptophan oxygenase (TDO)	M
U61836	Putative cyclin G1 interacting protein	M
U65404	Erythroid-specific transcription	M
	factor EKLF
U72515	C3f	M
U73167	H_LUCA14.2a	M
U73524	Putative ATP/GTP-binding protein (HEAB)	L
U90544	Sodium phosphate transporter (NPT3)	M
V01514	Alpha-fetoprotein (AFP)	H
X02176	Complement component C9	M
X02544	Alpha1-acid glycoprotein (orosomucoid)	H
X03473	Histone H1(0)	M
X04898	Apolipoprotein	H
X05309	C3b/C4b receptor (CR1) F allotype	L
X06482	Theta 1-globin	M
X06562	Growth hormone receptor	L
X13293	B-myb	M
X13589	Aromatase (estrogen synthetase)	LM
X14329	Carboxypeptidase N small subunit	LM
	(EC 3.4.17.3)
X14690	Plasma inter-alpha-trypsin inhibitor	H
	heavy chain H(3)
X15422	Mannose-binding protein C	M
X16260	Inter-alpha-trypsin inhibitor	H
	subunit 3
X16983	Integrin alpha-4 subunit	L
X17059	NAT1 gene for arylamine	L
	N-acetyltransferase
X17254	Transcription factor Eryf1	M
X51688	Cyclin A	LM
X53414	Peroxisomal L-alanine: glyoxylate	MH
	aminotransferase
X55668	Proteinase 3	M
X56692	C-reactive protein	M
X56741	Rab8	L
X58199	Beta adducin	M
X59618	RR2 small subunit ribonucleotide	LM
	reductase
X59711	CAAT-box DNA binding protein subunit A	L
X59812	CYP 27 vitamin D3 25-hydroxylase	M
X62822	Beta-galactoside alpha-2,6-	LM
	sialyltransferase
X63097	Rhesus polypeptide (RhXIII)	L
X64594	Erythrocyte plasma membrane	MH
	glycoprotein
X64877	Serum protein	LM
X65550	Antigen of monoclonal antibody Ki-67	L
X74330	DNA primase (subunit p48)	L
X75315	Seb4B	M
X77737	Red cell anion exchanger (EPB3, AE1,	H
	Band 3)
X80907	P85 beta subunit of	M
	phosphatidyl-inositol-3-kinase
X91148	Microsomal triglyceride transfer	LM
	protein
X98337	Complement factor H-related protein 4	M
Y00317	Liver microsomal UDP-	LM
	glucuronosyltransferase (UDPGT)
Z15005	CENP-E	LM
Z26248	Eosinophil granule major basic	LM
	protein
Z28339	Delta 4-3-oxosteroid 5 beta-	LM
	reductase
Z32684	XK membrane transport protein	M
Z83821	DNA sequence from PAC 296K21 on	H
	chromosome X contains cytokeratin
	exon, delta-aminolevulinate synthase
	(erythroid); 5-aminolevulinic acid
	synthase
Z84721	DNA sequence from cosmid GG1	H
	from a contig from the tip of
	the short arm of chromosome 16,
	spanning 2Mb of 16p13.3
Uniquely Expressed in Fetal Lung
D87071	KIAA0233	LM
HG4638-	Spliceosomal Protein Sap 49	L
HT5050
U18671	Stat2	L
U40434	Mesothelin or CAK1 antigen precursor	LM
X52896	Dermal fibroblast elastin	M
X97748	PTX3	LM
Uniquely Expressed in Adult Brain
D87463	KIAA0273	M
HG2259-	Tubulin, Alpha 1, Isoform 44	M
HT2348
HG3437-	Myelin Proteolipid Protein,	H
HT3628	Alt. Splice 2
L00354	Cholecystokinin (CCK)	M
L76224	NMDA receptor	M
L76627	Metabotropic glutamate receptor 1	L
	alpha (mGluR1alpha)
M55267	EV12 protein	LM
M59488	S100 protein beta-subunit	M
S50017	2′,3′-cyclic nucleotide	M
	3′-phosphodiesterase
S69965	Beta-synuclein	M
U01824	Glutamate/aspartate transporter II	M
U06698	Neuronal kinesin heavy chain	LM
U27768	RGP4	M
U62801	Protease M	M
U82532	GDI-dissociation inhibitor RhoGDIgammma	LM
X59065	FGF, exon 3	M
X64810	PC1/PC3	LM
X73882	E-MAP-115	LM
X99076	NRGN, exons 2, 3 & 4 (joined CDS)	H
Z48051	Myelin oligodendrocyte	M
	glycoprotein (MOG)
Uniquely Expressed in Adult Kidney
J04093	Phenol UDP-glucuronosyl-transferase	LM
	(UDPGT)
L13258	Renal Na/Pi-cotransporter	M
M19878	Calbindin 27, exons 1 and 2, and Alu	M
	repeat
S77576	ERV9 reverse transcriptase homolog	L
	(clone RT18)
U17418	Hormone/parathyroid hormone-related	M
	peptide receptor
X13227	D-amino acid oxidase	M
X60708	PcHDP7, liver dipeptidyl peptidase IV	L
Uniquely Expressed in Adult Uterus
D21337	Collagen	L
D86961	KIAA0206	L
HG721-	Placental Protein 14, Endometrial	M
HT4828	Alpha 2 Globulin, Alt. Splice 3
L00205	K6b (epidermal keratin, type II)	L
L02785	Colon mucosa-associated (DRA)	L
L06419	Lysyl hydroxylase (PLOD)	LM
L08044	Intestinal trefoil factor	LM
L10343	Elafin	M
L14848	MHC class I-related protein	L
M19888	Small proline rich protein (sprI)	M
M21121	T cell-specific protein (RANTES)	L
M21389	Keratin type II (58 kD)	M
M55543	Guanylate binding protein isoform II	L
	(GBP-2)
M59979	Prostaglandin endoperoxide synthase	L
M60284	Neurokinin A receptor (NK-2R)	LM
M62783	Alpha-N-acetylgalactosaminidase	L
M85276	NKG5	M
M86757	Psoriasin	M
M86849	Connexin 26 (GJB2)	L
M96233	Transferase class mu number 4 (GSTM4)	LM
S66896	Squamous cell carcinoma antigen,	L
	serine protease inhibitor
S72493	Keratin 16 homolog	M
S81661	Keratinocyte growth factor	L
U07969	Intestinal peptide-associated	L
	transporter HPT-1
U09278	Fibroblast activation protein	L
U09584	PL6 protein (PL6)	L
U11717	Calcium activated potassium channel	L
	(hslo)
U24488	Tenascin-X (XA)	M
U25138	MaxiK potassium channel beta subunit	M
U37283	Microfibril-associated glycoprotein-2	M
	MAGP-2
U43185	Signal transducer and activator	L
	of transcription Stat5A
U60325	DNA polymerase gamma, nuclear gene	L
	encoding mitochondrial protein
U76764	CD97	LM
U81523	Endometrial bleeding associated	M
	factor
X03635	Oestrogen receptor	M
X06256	Fibronectin receptor alpha subunit	LM
X07695	Cytokeratin 4 C-terminal region	M
X07696	Cytokeratin 15	L
X16662	Vascular anticoagulant-beta (VAC-beta)	L
X54162	64 Kd autoantigen expressed in	M
	thyroid and extra-ocular muscle
X63629	P cadherin	L
X75535	PxF protein	L
X83857	Prostaglandin E receptor (EP3a1)	L
X92521	MMP-19 protein	L
X93510	37 kDa LIM domain protein	LM
X96719	AICL (activation-induced C-type lectin)	LM
X98311	Carcinoembryonic antigen, CGM2	L
Y07755	S100A2, exon 1, 2 and 3	M
Uniquely Expressed in Adult Testis
D17570	Zona-pellucida-binding protein (sp38).	M
D50925	KIAA0135	L
D64109	Tob family	L
D78333	Testis-specific TCP20	M
D78334	Ankyrin motif	MH
HG2075-	Camp-Responsive Element Modulator,	M
HT2137	Alt. Splice 1
HG36-	Polymyositis/Scleroderma (Pm-Scl)	L
HT4101	Autoantigen, Alt. Splice 2
HG3725-	Insulin-Like Leydig Hormone	M
HT3981
HG4316-	Transketolase-Like Protein	L
HT4586
L01042	HIV1 tata element modulatory factor	L
L07515	Heterochromatin protein homologue (HP1)	LM
L14754	DNA-binding protein (SMBP2)	LM
L22214	Denosine A1 receptor (ADORA1),	L
	exons 1-6
L36861	Guanylate cyclase activating protein	L
	(GCAP), exons 1-4
L42324	G protein-linked receptor (GPCR)	L
L76687	Grb14	L
M13981	Inhibin A-subunit	M
M14565	Cholesterol side-chain cleavage enzyme	L
	P450scc
M21539	Small proline rich protein (sprII)	L
M31606	Phosphorylase kinase (PSK-C3)	M
M63256	Major Yo paraneoplastic antigen (CDR2)	L
M73077	Glucocorticoid receptor repression	LM
	factor 1 (GRF-1)
M86808	Pyruvate dehydrogenase complex (PDHA2)	L
M91438	Kazal-type serine proteinase (HUSI-II)	M
S68134	CREM, cyclic AMP-responsive element	LM
	modulator beta isoform
S78873	Zn2+ binding protein/guanine	L
	nucleotide exchange factor
U03644	Recepin	L
U10362	GP36b glycoprotein	L
U13680	Lactate dehydrogenase-C (LDH-C)	M
U15422	Protamine 1 (PRM1), protamine 2 (PRM2)	H
	and transition protein 2 (TNP2)
U17032	P190-B (p190-B)	L
U17280	Steroidogenic acute regulatory protein	LM
	(StAR)
U19147	GAGE-6 protein	LM
U20362	Tg737	LM
U22815	LAR-interacting protein 1a	L
U31929	Orphan nuclear receptor (DAX1)	L
U38175	HuR RNA binding protein (HuR)	L
U41763	Muscle specific clathrin heavy chain	L
	(CLTD)
U43944	Breast cancer cytosolic NADP(+)-	L
	dependent malic enzyme
U47054	Putative mono-ADP-ribosyltransferase	LM
	(htMART)
U58970	Putative outer mitochondrial membrane	M
	34 kDa Translocase hTOM34
U60665	Testis specific basic protein (TSBP)	L
U65011	Preferentially expressed antigen of	LM
	melanoma (PRAME)
U65092	Melanocyte-specific gene 1 (msg1)	M
U65533	Regulator of nonsense transcript	L
	stability (RENT1)
U65918	Putative RNA binding protein (DAZH)	L
U66726	Testis specific RNA binding protein	LM
	(SPGYLA)
U70981	Interleukin-13 receptor	L
U78722	Zinc finger protein 165 (Zpf165)	L
U79266	Clone 23627	L
U84720	Export protein Rael (RAE1)	LM
U89606	Pyridoxal kinase	M
X04445	InhA gene exon 1 (and joined CDS)	LM
X05246	Testis-specific PGK-2 gene for	M
	phosphoglycerate kinase (ATP:
	3-phospho-D-glycerate
	1-phosphotransferase, EC 2.7.2.3)
X07948	Transition protein 1 (TP1)	H
X12433	PHS1-2, ORF homologous to membrane	LM
	Receptor proteins
X14968	RII-alpha subunit of cAMP dependent	L
	protein kinase
X68285	Glycerol kinase	L
X69398	OA3 antigenic surface determinant	L
X70218	Protein phosphatase X	LM
X78706	Carnitine acetyltransferase	M
X78711	Glycerol kinase testis specific 1	L
X78712	Glycerol kinase testis specific 2	M
X79200	SYT-SSX, synovial sarcoma	M
	translocation junction
X89960	Mitochondrial capsule selenoprotein	M
X95239	Cysteine-rich secretory protein-2/	M
	type I
X99374	Fertilin beta	L
Y00970	Acrosin (EC 3.4.21.10)	M
Y12856	AMP-activated protein kinase alpha-1	L
Z22780	Cylicin	L
Z46788	Cylicin II	L
Z46967	Calicin	M
Z48570	Sp17	LM
Z49105	HD21	M
Z50115	Thimet oligopeptidase	L
	(metalloproteinase)
Z75190	Apolipoprotein E receptor 2.	L
Uniquely Expressed in Fetal Brain
HG1996-	Guanine Nucleotide-Binding Protein	LM
HT2044	Rap2, Ras-Oncogene Related
HG4063-	Transcription Factor Hbf-2	M
HT4333
L07919	Homeodomain protein DLX-2	M
L13744	AF-9	LM
M64358	Rhom-3	LM
M88461	Neuropeptide Y peptide YY receptor	M
U00802	Drebrin E2 (DBN1)	M
U04735	Microsomal stress 70 protein ATPase	L
	core (stch)
U09413	Zinc finger protein ZNF135	L
U11701	LIM-homeobox domain protein (hLH-2)	M
U35234	Protein tyrosine phosphatase sigma	M
U43843	H-neuro-d4 protein	M
U64871	Putative G protein-coupled receptor	L
	(GPR19)
U66198	Fibroblast growth factor homologous	M
	factor 2 (FHF-2)
U79247	Clone 23599	LM
U81262	Lerk-5 (Lerk-5)	LM
X95425	EHK-1 receptor tyrosine kinase	L
Z11933	N-Oct 3, N-Oct5a, and N-Oct 5b proteins	M
Z70220	Unknown protein (clone ICRFp507O0882)	M
Uniquely Expressed in Adult Pancreas
AF014958	Chemokine receptor X (CKRX)	LM
D31797	CD40 ligand (CD40L)	LM
J00268	Insulin	H
J02883	Colipase	H
J05125	Triglyceride lipase	H
L08010	Reg gene homologue	H
L14813	Carboxyl ester lipase like protein	MH
	(CELL)
M16652	Pancreatic elastase IIA	H
M16653	Elastase IIB	H
M21056	Pancreatic phospholipase A-2 (PLA-2)	H
M22612	Pancreatic trypsin 1 (TRY1)	H
M24349	Parathyroid hormone-like protein (PLP)	L
M24400	Chymotrypsinogen	H
M55131	Cystic fibrosis transmembrane	M
	conductance regulator (CFTR)
M74096	Long chain acyl-CoA dehydrogenase	L
	(ACADL)
M81057	Procarboxypeptidase B	H
M93284	Pancreatic lipase related protein 2	H
	(PLRP2)
S82198	Caldecrin, serum calcium-decreasing	H
	factor
X54457	Bile-salt-stimulated lipase (BSSL)	H
X67318	Procarboxypeptidase A1	H
X71877	Chymotrypsin-like protease CTRL-1	H
Y00705	Pancreatic secretory inhibitor	H
	(expressed in neoplastic tissue)
Y08134	ASM-like phosphodiesterase 3b	LM
*The abundance levels in copies per cell: L < 5, LM > 5 < 10, M > 10 < 50, MH > 50 < 100, H > 100.

Conclusion

The present invention provides methods and compositions for identifying and using maintenance genes. It is to be understood that the above description is intended to be illustrative and not restrictive. Many variations of the invention will be apparent to those of skill in the art upon reviewing the above description. By way of example, the invention has been described primarily with reference to the use of a high density oligonucleotide array, but it will be readily recognized by those of skill in the art that other nucleic acid arrays, other methods of measuring transcript levels and gene expression monitoring at the protein level could be used. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

All references cited in this application are incorporated by reference for all purposes.

Claims

1. A method for identifying a maintenance gene comprising: determining the expression of at least one hundred genes in at least two different types of tissues in two different developmental stages; and indicating a gene that is expressed at the same level in said tissues in said stages as said maintenance gene.

2-12. (Cancelled)