Molecular cloning and chromosomal mapping of a novel five-span transmembrane protein gene, M83

In an attempt to identify novel transmembrane molecules expressed on hematopoietic cells, we identified a novel transmembrane protein gene, M83. Cloning of the full-length cDNAs of human and mouse M83 revealed that M83 encodes a type I transmembrane protein with a region containing five hydrophobic segments within the C-terminal part of the protein, suggesting that M83 is a five-span transmembrane molecule. The M83 protein was expressed on the cell surface as a glycosylated protein with a molecular mass of 84 kDa. The M83 gene was localized to human chromosome 16p13.3, mouse chromosome 17B1, and rat chromosome 10q12.3 distal. In human, M83 mRNA was highly expressed in placenta, pancreas, and lymphohematopoietic tissues including peripheral blood, spleen, and bone marrow. Among hematopoietic cells, it was highly expressed in resting T lymphocytes and was downregulated by cell activation, suggestive of its biological role related to the T cell resting status.     

Cloning and characterization of a novel human leptin receptor overlapping transcript-like 1 gene (LEPROTL1)

A new full-length cDNA encoding a novel protein was isolated from our human fetal brain cDNA library. The cDNA consists of 2701 bp and has a putative open reading frame encoding 131 amino acids which possesses a JAK binding site (Pro(46)-Ile-Pro(48) which is preceded by a cluster of hydrophobic residues) and is highly homologous to the leptin receptor gene-related protein (OB-RGRP). Northern blot analysis showed that this new gene is widely expressed in human tissues and radiation hybrid mapping placed the gene to human chromosome 8p21.1-8p21.2.     

Kirrel2, a novel immunoglobulin superfamily gene expressed primarily in beta cells of the pancreatic islets

A novel immunoglobulin superfamily (Igsf) protein gene was discovered by computational analysis of human draft genomic DNA, and multiple cDNA clones were obtained. The protein encoded by this gene contains five Ig domains, one transmembrane domain, and an intracellular domain. It has significant similarity with several known Igsf proteins, including Drosophila RST (irregular chiasm C-roughest) protein and mammalian KIRREL (kin of irregular chiasm C-roughest), NEPH1, and NPHS1 (nephrin) proteins. All these proteins have multiple Ig domains, possess properties of cell adhesion molecules, and play important roles in organ development. RT-PCR and Northern blot results indicate this gene is predominantly expressed in pancreas, and public sequence databases indicate there is also expression in the nervous system. We have named this gene Kirrel2 (kin of irregular chiasm-like 2), to reflect its similarity to irregular chiasm C-roughest and Kirrel. Four splice forms of Kirrel2 were observed, including two that we cloned from pancreas mRNA as well as two GenBank entries, one from the brain and one from a retinoblastoma cell line. A partial cDNA clone of the mouse orthologue was obtained by RT-PCR from mouse brain, and the inferred protein sequence has 85% sequence identity to the human protein. Immunohistochemical staining results indicate that the KIRREL2 protein is conserved from rodents to primates, and it is highly expressed in pancreatic islets. RT-PCR results on mouse pancreatic cell lines indicate that expression in the pancreas is restricted to beta cells. Thus, KIRREL2 protein is a beta-cell-expressed Ig domain protein and may be involved in pancreas development or beta cell function.     

表达序列标签数据库搜索鉴定小鼠UBAP1基因及其数字化表达分析

UBAP1(ubiquitin associated protein 1)基因是最近克隆的一个定位于人类染色体9p21-22鼻咽癌杂合性丢失高频区的泛肽相关蛋白家族新成员.为了深入研究UBAP1基因的功能,利用计算机对表达序列标签(expressed sequence tag, EST)、UniGene等数据库进行综合搜索分析,结合cDNA克隆测序的方法, 成功地获得了UBAP1基因在小鼠中的同源基因.小鼠UBAP1基因cDNA全长为2 676 bp,编码一个由441个氨基酸组成的蛋白质,在其蛋白质C端只有一个泛肽相关功能域（UBA domain）.与人UBAP1基因相比,两者编码的氨基酸序列有89%相同.基于EST的数字化表达分析显示UBAP1基因在小鼠正常组织中广泛高表达.     

Placental expression and chromosomal localization of the human Gcm 1 gene.

Although gcm was first recognized for its role in specifying glial cell fate in Drosophila melanogaster, its mammalian counterparts are expressed predominantly in non-neural tissues. Here we demonstrate expression of the mouse and human GCM 1 proteins in placenta. We have prepared a highly specific antibody that recognizes the GCM 1 protein and have used it to assess the temporal and spatial expression profile of the protein. In both mouse and human placenta, the protein is associated with cells that are involved with exchange between maternal and fetal blood supplies: the labyrinthine cells of the mouse placenta and the syncytio- and cytotrophoblasts of the human placenta. Using the full-length hGcm 1 cDNA as a probe, we have mapped the gene on human chromosome 6p12 by fluorescent in situ hybridization.     

Molecular cloning and characterization of a novel human protein phosphatase 2C cDNA (PP2C ε)

We have isolated a novel cDNA from the human fetal brain cDNA library with homology to the Mg2+ -dependent serine/threonine protein phosphatase 2C (PP2C) family. The cDNA is 3055 bp in length, and the predicted coding region encodes a 360-amino-acid protein, which shows 99% identity to the PP2C epsilon from rat and mouse. Then we term it human PP2C epsilon gene. The gene is mapped to chromosome 3q26.1 and contains 4 exons. RT-PCR analysis shows that the PP2C epsilon is widely expressed in human tissues and the expression levels in heart, placenta, lung, liver, kidney, and pancreas are relatively high.     

Identification,genomic organization and mRNA expression of CRELD1, the founding member of a unique family of matricellular proteins

We have isolated and characterized a unique gene that encodes a highly conserved membrane bound extracellular protein that defines a new epidermal growth factor-related gene family. The CRELD1 (Cysteine-Rich with EGF-Like Domains 1) gene (previously known as cirrin) was cloned from a human chromosome 3 BAC. Mapping of the gene confirmed its position at chromosome 3p25.3. The gene is ubiquitously expressed in early development and later becomes more markedly expressed in the developing heart, limb buds, mandible and central nervous system. Expression persists in adulthood in most tissues. Sequence analysis suggests that this is a cell adhesion protein. The mouse orthologue was cloned and mapped to the syntenic region of mouse chromosome 6. Orthologues or homologues have also been identified for cow, Chinese hamster, Drosophila and Caenorhabditis elegans. The CRELD1 gene is deleted in the human cytogenetic disorder 3p- syndrome and is in the region of loss of heterozygosity for several types of cancer. A potential role for this protein in these disorders is discussed.     

Type 1 human T-cell leukemia virus small envelope protein expressed in mouse cells by using a bovine papilloma virus-derived shuttle vector.

In an attempt to express the small (transmembrane) envelope protein p21e of type 1 human T-cell leukemia (lymphotrophic) virus (HTLV-1) exclusive of other viral gene products, we have constructed a recombinant plasmid clone (pMBE-1) in a bovine papillomavirus-derived mammalian expression vector. Mouse C127 cells transfected with the pMBE-1 plasmid expressed the introduced HTLV-1 viral gene(s) as demonstrated by Northern blot and indirect immunofluorescence with natural human antisera. The transfected mouse cells were injected into BALB/c mice, and a monoclonal antibody was recovered which specifically recognizes a 21-kilodalton protein present in HTLV-1 virions, indicating that the pMBE-1 plasmid encodes the small envelope protein.     

Genomic organization and expression profile of the small GTPases of the RhoBTB family in human and mouse

Members of the RhoBTB subfamily of Rho GTPases are present in vertebrates, Drosophila and Dictyostelium. RhoBTB proteins are characterized by a modular organization, consisting of a GTPase (guanosine triphosphatase) domain, a proline rich region, a tandem of two BTB (Broad-Complex, Tramtrack, and Bric à brac) domains and a C-terminal region of unknown function and might act as docking points for multiple components participating in signal transduction cascades. We have determined the genomic organization and the expression pattern of the three RHOBTB genes of human and mouse. The exon-intron organization of each gene is conserved in three vertebrate species (human, mouse and Fugu). RHOBTB1 and RHOBTB2 have a similar exon-intron organization and are closely related to the single gene encoding the RhoBTB orthologs of two insect species. By contrast, the exon-intron organization of RHOBTB3 differed substantially from that of the two other genes, indicating that this gene arose by a duplication event independent of the one that gave rise to RHOBTB1 and RHOBTB2. RHOBTB1 (located on chromosome 10) and RHOBTB3 (located on chromosome 5) appear ubiquitously expressed. However, they display a differential pattern of expression: RHOBTB1 showed high levels in stomach, skeletal muscle, placenta, kidney and testis, whereas RHOBTB3 was highly expressed in neural and cardiac tissues, pancreas, placenta and testis. RHOBTB2 (located on chromosome 8) showed much lower levels of expression than the other two human RHOBTB genes and it was most abundant in neural tissues. The expression patterns of the human and mouse genes were roughly comparable. All three genes were also detected in fetal tissues, and in a number of cell lines RHOBTB3 predominates. RHOBTB genes are upregulated in some cancer cell lines, suggesting that these proteins might participate in tumorigenesis.     

Sequence of the human factor VIII-associated gene is conserved in mouse.

cDNA and genomic clones corresponding to the human factor VIII-associated gene (F8A) were isolated from mouse cDNA and F8A-enriched genomic libraries. The sequences of these clones revealed an intronless gene coding for 380 amino acids, with 85% identity to the predicted human sequence. The single murine gene copy is genetically linked to factor VIII, but appears to lie outside the factor VIII gene by physical mapping. Like the human gene, the mouse F8A gene is highly expressed in a wide variety of tissues. This evolutionary comparison has helped to clarify the derived amino acid sequence in the human and strongly supports the hypothesis that the F8A gene encodes a protein.     

Molecular cloning and characterization of a novel human kinase gene,PDIK1L

We isolated a 4301-bp cDNA from a human foetal brain cDNA library by high-throughput cDNA sequencing. It encodes a protein of 341 amino acids, which shows 69% identity with the human kinase CLIK1 (AAL99353), which was suggested to be the CLP-36 interacting kinase. Bioinformatics analysis suggests that the putative kinase may interact with PDZ and LIM domain proteins. Therefore the protein and its cDNA were named ’PDLIM1 interacting kinase 1 like’ (PDIK1L; nomenclature approved by the HUGO Gene Nomenclature Committee). Ensembl Genome Browser locatedPDIK1L to human chromosome 1p35.3. It spans about 13.7 kb and consists of four exons and three introns. Multiple-tissue cDNA panel PCR revealed that the gene is expressed widely in human tissues: liver, kidney, pancreas, spleen, thymus and prostate. The protein appears to be localized to the nucleus.     

The mouse one P-domain (pS2) and two P-domain (mSP) genes exhibit distinct patterns of expression

We have previously shown that the human pS2 gene, which codes for a secreted peptide of 60 amino acids, is expressed in a number of human carcinomas, including carcinomas of the breast, the pancreas, and the large bowel. Strong pS2 gene expression was also observed in the normal gastric mucosa and in the regenerative tissues surrounding ulcerous lesions of the gastrointestinal tract. A number of pS2 similar peptides, designated as P-domain peptides, have been described, notably the porcine (PSP), murine (mSP), and human (hSP) spasmolytic polypeptides, which correspond to duplicated pS2 proteins. We have now cloned a mouse homolog of the human pS2 cDNA to dispose of an animal model to study the pS2 protein function, which remains unknown at the present time. We show that the mouse putative pS2 protein sequence and the physiological pattern of expression of the mouse pS2 gene are well conserved. The mouse pS2 gene is highly expressed in the stomach mucosa cells, whereas no pS2 gene expression could be detected in the mouse mammary gland, even during postnatal development processes dependent on growth factors or hormones. Using in situ hybridization, we show that although coexpressed in the fundus, the antrum and the antrum-pyloric regions of the stomach, the mouse pS2 and mSP genes exhibit distinct and complementary cellular patterns of expression.     

Tissue Distribution, Genomic Structure, and Chromosome Mapping of Mouse and Human Eukaryotic Initiation Factor 4E-Binding Proteins 1 and 2

Two related eukaryotic initiation factor-4E binding proteins (4E-BP1 and 4E-BP2) were recently characterized for their capacity to bind specifically to eIF4E and inhibit its function. Here, we determined the cDNA sequence, tissue distribution, genomic structure, and chromosome localization of murine and human 4E-BP1 and 4E-BP2. Mouse 4E-BP1 and 4E-BP2 consist of 117 and 120 amino acids and exhibit 91.5 and 95.0% identity, respectively, to their human homologues. 4E-BP1 mRNA is expressed in most tissues, but is most abundant in adipose tissue, pancreas, and skeletal muscle, while 4E-BP2 mRNA is ubiquitously expressed. The structures of the mouse 4E-BP1 and 4E-BP2 were determined. The 4E-BP1 gene consists of three exons and spans ∼16 kb. In addition, two 4E-BP1 pseudogenes exist in the mouse genome. The 4E-BP2 gene spans approximately 20 kb and exhibits an identical genomic organization to that of 4E-BP1, with the protein coding portion of the gene divided into three exons. There are no pseudogenes for 4E-BP2. The chromosomal locations of 4E-BP1 and 4E-BP2 were determined in both mice and humans by fluorescencein situhybridization analysis. Mouse 4E-BP1 and 4E-BP2 map to chromosomes 8 (A4-B1) and 10 (B4-B5), respectively, and human 4E-BP1 and 4E-BP2 localize to chromosomes 8p12 and 10q21–q22, respectively.     

DRG represents a family of two closely related GTP-binding proteins

In a previous publication we identified a novel human GTP-binding protein that was related to DRG, a developmentally regulated GTP-binding protein from the central nervous system of mouse. Here we demonstrate that both the human and the mouse genome possess two closely related drg genes, termed drg1 and drg2. The two genes share 62% sequence identity at the nucleotide and 58% identity at the protein level. The corresponding proteins appear to constitute a separate family within the superfamily of the GTP-binding proteins. The DRG1 and the DRG2 mRNA are widely expressed in human and mouse tissues and show a very similar distribution pattern. The human drg1 gene is located on chromosome 22q12, the human drg2 gene on chromosome 17p12. Distantly related species including Caenorhabditis elegans, Schizosaccharomyces pombe and Saccharomyces cerevisiae also possess two drg genes. In contrast, the genomes of archaebacteria (Halobium, Methanococcus, Thermoplasma) harbor only one drg gene, while eubacteria do not seem to contain any. The high conservation of the polypeptide sequences between distantly related organisms indicates an important role for DRG1 and DRG2 in a fundamental pathway.