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Biomedical subjects

T B Shows

Publications and source records attributed to T B Shows.

At least 19 recordsLinked to original sources
PubMed1995

The orphan G-protein-coupled receptor-encoding gene V28 is closely related to genes for chemokine receptors and is expressed in lymphoid and neural tissues.

A polymerase chain reaction (PCR) strategy with degenerate primers was used to identify novel G-protein-coupled receptor-encoding genes from human genomic DNA. One of the isolated clones, termed V28, showed high sequence similarity to the genes encoding human chemokine receptors for monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein 1 alpha (MIP-1 alpha)/RANTES, and to the rat orphan receptor-encoding gene RBS11. When RNA was analyzed by Northern blot, V28 was found to be most highly expressed in neural and lymphoid tissues. Myeloid cell lines, particularly THP.1 cells, showed especially high expression of V28. We have mapped V28 to human chromosome 3p21-3pter, near the MIP-1 alpha/RANTES receptor-encoding gene.

Amino Acid Sequence↗
PubMed1995

Genomic organization and chromosomal localization of the gene encoding human P-selectin glycoprotein ligand.

The gene for P-selectin glycoprotein ligand (PSGL-1) has been cloned from a human placenta genomic DNA library. A single intron of approximately 9 kilobases was found in the 5'-untranslated region and the complete coding region resides in exon 2. The genomic clone differs from the cDNA clone isolated from HL-60 cells in that it encodes an extra copy of the decameric repeat located in the extracellular domain of PSGL-1. Further analysis indicated that the PSGL-1 genes of HL-60 and U-937 cells contain 15 repeats, whereas the PSGL-1 genes of polymorphonuclear leukocytes, monocytes, and several other cell lines contain 16 repeats. Transfection experiments did not indicate a functional difference between these two variants of PSGL-1. The two previously observed PSGL-1 mRNA species of 2.5 and 4 kilobases most likely arise from differential utilization of polyadenylation signal sequences. The organization of the PSGL-1 gene closely resembles those of CD43 and human platelet glycoprotein GPIb alpha, both of which have an intron in the 5'-noncoding region, a long second exon containing the complete coding region, and TATA-less promoters. The gene for human PSGL-1, which has been designated SELPLG by the Human Gene Nomenclature Committee, was mapped to chromosome 12q24 using Southern blot analysis of DNA from a set of human-mouse cell hybrids, and fluorescent in situ hybridization on metaphase chromosome spreads.

Amino Acid Sequence↗
PubMed1995

Chromosomal localization of the gene encoding the human DNA helicase RECQL and its mouse homologue.

We have determined the chromosomal location of the human and mouse genes encoding the RECQL protein, a putative DNA helicase homologous to the bacterial DNA helicase, RecQ. RECQL was localized to human chromosome 12 by analysis of human-rodent somatic cell hybrid DNA; fine mapping of RECQL by fluorescence in situ hybridization revealed its chromosomal location to be 12p11-p12. The corresponding mouse gene, Recql, was mapped to the telomeric end of mouse chromosome 6 by analysis of DNA from an interspecific cross.

Adenosine Triphosphatases↗
PubMed1995

Mapping of ribosomal protein S3 and internally nested snoRNA U15A gene to human chromosome 11q13.3-q13.5.

The mammalian ribosome is a massive structure composed of 4 RNA species and about 80 different proteins. One of these ribosomal proteins, S3, appears to function not only in translation but also as an endonuclease in repair of UV-induced DNA damage. Moreover, the first intron of human RPS3 transcripts is processed to generate U15A, a small nucleolar RNA. We localized the nested RPS3/U15A genes to the immediate vicinity of D11S356 and D11S533 on human chromosome 11q13.3-q13.5 using a combination of somatic cell hybrid analysis, fluorescence in situ hybridization, and YAC/STS content mapping. These findings add to the evidence that genes encoding ribosomal proteins are scattered about the human genome.

Animals↗
PubMed1995

Complex MLL rearrangement in a patient with T-cell acute lymphoblastic leukemia.

MLL (also known as ALL-I, HTRX, or HRX) gene translocations are among the most common chromosomal abnormalities recognized in both B-lineage acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). However, MLL gene rearrangements are uncommon in T-cell ALL. We recently detected an MLL gene rearrangement in a patient with typical T-cell ALL. We recently detected an MLL gene rearrangement in a patient with typical T-cell ALL (CD2+, CD4+, CD5+, CD7+, CD8+, HLA DR-) and an apparently normal karyotype (46,XX). The rearrangement was cloned and characterized; a DNA fragment distal to the breakpoint was mapped by fluorescence in situ hybridization (FISH) to 19p13, indicating that the leukemic blasts had undergone a cytogenetically undetected rearrangement involving chromosomes 11 and 19. A reverse transcriptase-polymerase chain reaction (RT-PCR) assay demonstrated an in-frame fusion mRNA between the amino terminus of MLL and the carboxy terminus of ENL (also known as MLLT1 or LTG19), a gene that has been mapped to 19p13. In addition, MLL sequences distal (telomeric) to the breakpoint were deleted from the genome, which precludes the formation of a reciprocal ENL/MLL fusion protein. These findings suggest that an MLL/ENL fusion protein (and not a reciprocal ENL/MLL fusion) was likely to be pathogenic in this patient, and they reinforce previous studies showing that leukemic blasts with apparently normal karyotype may harbor MLL rearrangements. Additionally, this report provides the first conclusive evidence of an MLL/ENL gene fusion characterized at a molecular level in a patient with T-cell ALL.

Base Sequence↗
PubMed1995

Human cDNA clones that modify radiomimetic sensitivity of ataxia-telangiectasia (group A) cells.

Genes responsible for genetic diseases with increased sensitivity to DNA-damaging agents can be identified using complementation cloning. This strategy is based on in vitro complementation of the cellular sensitivity by gene transfer. Ataxia-telangiectasia (A-T) is a multisystem autosomal recessive disorder involving cellular sensitivity to ionizing radiation and radiomimetic drugs. A-T is genetically heterogeneous, with four complementation groups. We attempted to identify cDNA clones that modify the radiomimetic sensitivity of A-T cells assigned to complementation group [A-T(A)]. The cells were transfected with human cDNA libraries cloned in episomal vectors, and various protocols of radiomimetic selection were applied. Thirteen cDNAs rescued from survivor cells were found to confer various degrees of radiomimetic resistance to A-T(A) cells upon repeated introduction, and one of them also partially influenced another feature of the A-T phenotype, radioresistant DNA synthesis. None of the clones mapped to the A-T locus on chromosome 11q22-23. Nine of the clones were derived from known genes, some of which are involved in cellular stress responses. We concluded that a number of different genes, not necessarily associated with A-T, can influence the response of A-T cells to radiomimetic drugs, and hence the complementation cloning approach may be less applicable to A-T than to other diseases involving abnormal processing of DNA damage.

Antibiotics, Antineoplastic↗
PubMed1995

The human laminin beta 2 chain (S-laminin): structure, expression in fetal tissues and chromosomal assignment of the LAMB2 gene.

The sequence of the human laminin beta 2 chain (previously s-laminin) was derived from cloned cDNAs. The complete translation product has 1798 amino acid residues, including a 32-residue signal peptide. The human chain lacks the tripeptide sequence LRE in domain I which is present in the rat polypeptide chain and has been shown to promote motor neuronal cell adhesion. The human gene (LAMB2) was localized to chromosome 3p21 using somatic cell hybrids and fluorescent in situ hybridization analysis. Northern and in situ hybridization analyses from numerous fetal tissues revealed that the beta 2 chain is generally widely expressed. beta 2, but not beta 1, was shown by in situ hybridization to be expressed in fetal brain and renal glomeruli. In fetal skin, beta 2 was expressed both in epidermal and dermal cells, while beta 1 was expressed only in the dermis. Expression of beta 2 in fetal liver was seen in hepatocytes, while no signals were observed for beta 1. In lung, both beta 1 and beta 2 were expressed in alveoli and bronchial smooth muscle cells, whereas only the beta 2 chain was expressed in bronchial epithelial cells. In striated muscle, however, the beta 1 chain, but not beta 2, was expressed. These results indicate different biological roles for the laminin beta 1 and beta 2 chains.

Amino Acid Sequence↗
PubMed1995

Three genes that encode human beta-galactoside alpha 2,3-sialyltransferases. Structural analysis and chromosomal mapping studies.

The synthesis of alpha 2,3-linked sialic acid to Gal(beta 1,3)GalNAc is mediated by at least three beta-galactoside alpha 2,3-sialyltransferases (EC 2.4.99.4, SiaT-4) that are encoded by three distinct genes. In contrast, only a single gene encodes the beta-galactoside alpha 2,6-sialyltransferase (EC 2.4.99.1, SiaT-1). This report assesses the relationship and nature of the SiaT-4 genes. Analysis of human-mouse somatic cell hybrids demonstrates that the sialyltransferase genes are dispersed in the human genome. The gene for SiaT-4 resides in chromosome 8, that for SiaT-4b resides in p21-p34 of chromosome 1 and that for SiaT-4c in q23.3-qter of chromosome 11. The gene symbols for these genes have been designated SIAT4A, SIAT4B and SIAT4C, respectively. To assess the structural organization of one of the SiaT-4 genes, a human SiaT-4a cDNA from submaxillary glands was isolated and characterized. Rapid amplification of cDNA 5' ends (5'-RACE) analysis indicates an unusually long 1 kb 5'-untranslated leader. The catalytic domain of the cloned sequence was expressed in transfected cells and was shown to be competent in mediating the specific synthesis of sialic acid alpha 2,3 to Gal(beta 1,3)GalNAc-R. Genomic sequences for SiaT-4a were also isolated and examined. The data demonstrate that coding information for SiaT-4a protein is dispersed into seven discrete exon segments in a manner reminiscent of the SiaT-1 gene. Furthermore, as in the SiaT-1 gene, intervening sequences interrupt both sialylmotif domains, regions that are conserved among all known sialyltransferases.

Amino Acid Sequence↗
PubMed1995

Chromosomal assignment of the heparin-binding cytokine genes MDK and PTN in mouse and man.

MDK and PTN are two members of a family of heparin-binding cytokines thought to be involved in a number of developmental processes. The locations for these genes were determined in man and mouse using somatic cell hybrid analysis and interspecific backcross analysis. Human MDK was mapped to 11p13-->p11. MDK in the mouse (Mdk) was mapped to a syntenic region of mouse Chromosome 2. A pseudogene of Mdk was mapped to mouse Chromosome 11. The closely related human gene PTN was mapped to a separate location on human chromosome region 7q22-->qter.

Animals↗
PubMed1995

The kinase insert domain receptor gene (KDR) has been relocated to chromosome 4q11-->q12.

Through in situ hybridization of a genomic DNA probe to metaphase chromosomes, we have localized the KDR gene to 4q11-->q12. This is the same locus as that for two other receptor tyrosine kinases, PDGFRA and KIT. This location for KDR differs from that which we previously reported using a cDNA probe. Using cDNA probes for both KDR and KIT identifies a locus at 4q31-->q32 which may uncover another cluster of receptor tyrosine kinase genes.

Chromosome Mapping↗
PubMed1995

The Brn-3 family of POU-domain factors: primary structure, binding specificity, and expression in subsets of retinal ganglion cells and somatosensory neurons.

A search for POU domain sequences expressed in the human retina has led to the identification of three closely related genes: Brn-3a, Brn-3b, and Brn-3c. The structure and expression pattern of Brn-3b was reported earlier (Xiang et al., 1993); we report here the structures and expression patterns of Brn-3a and Brn-3c. Antibodies specific for each Brn-3 protein were generated and shown to label only ganglion cells in a variety of vertebrate retinas. A complex pattern of strongly and weakly immunolabeled ganglion cells was observed in mouse, cat, and monkey retinae. In mouse and cat retinae, Brn-3a and Brn-3b proteins are found in a large fraction of ganglion cells, whereas Brn-3c is present in fewer ganglion cells. In the cat retina, anti-Brn-3a immunoreactivity was strong in the small ganglion cells (gamma cells) and weak in the remaining ganglion cells (alpha and beta cells); anti-Brn-3b immunoreactivity was present in all ganglion cells; and anti-Brn3c immunoreactivity was confined to the small ganglion cells. Immunolabeling of macaque retinae following retrograde labeling from the lateral geniculate nucleus revealed strong anti-Brn-3a immunoreactivity in a minority of retrogradely labeled P-type ganglion cells, and weak Brn-3a immunoreactivity in all of the remaining P- and M-type ganglion cells. In the same retinae, strong anti-Brn-3b immunoreactivity was seen in nearly all P-type ganglion cells and weak immunoreactivity in nearly all M-type ganglion cells. Each of the Brn-3-specific antibodies also labeled subsets of neurons in the dorsal root and trigeminal ganglia, suggesting that primary somatosensory neurons and retinal ganglion cells share genetic regulatory hierarchies. In vitro selection of an optimal DNA binding site using the Brn-3b POU domain has revealed a consensus [(A/G)CTCATTAA(T/C)] that is recognized by each of the Brn-3 POU domains and is distinct from binding sites previously described for other POU domain proteins.

Amino Acid Sequence↗
PubMed1994

A YAC contig spanning the ataxia-telangiectasia locus (groups A and C) at 11q22-q23.

Ataxia-telangiectasia (A-T) is an autosomal recessive disease involving cerebellar degeneration, immunodeficiency, cancer predisposition, chromosomal instability and radiosensitivity. A-T is heterogeneous, and the majority of A-T cases are associated with two complementation groups, A and C. The ATA and ATC loci are closely linked at chromosome 11q22-q23. Recombination mapping and linkage disequilibrium analysis have confined both loci between the markers D11S1817 and D11S927, spaced approximately 3.5 Mb apart. Isolation in yeast artificial chromosomes of the genomic segment defined by these loci is essential to identify the gene or genes containing the ATA and ATC mutations. A YAC contig spanning 4.5 Mb, which includes the D11S1817-D11S927 interval, was constructed using two whole genome libraries (ICRF and St. Louis), and a chromosome 11-specific library. Construction of this contig was expedited by prior generation of a region-specific ICRF sublibrary using Alu-PCR products derived from a radiation hybrid. The contig was expanded further by screening the libraries with Alu-PCR products derived from YAC clones and with STSs from YAC ends. YAC clones were aligned by fingerprinting with moderately repetitive probes.

Ataxia Telangiectasia↗
PubMed1994

Type I procollagen COOH-terminal proteinase enhancer protein: identification, primary structure, and chromosomal localization of the cognate human gene (PCOLCE).

Type I procollagen COOH-terminal proteinase (C-proteinase) enhancer, a glycoprotein that binds to the COOH-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity, was purified from mouse fibroblast culture media. Partial amino acid sequences obtained from proteolytic fragments were found to have identity with the deduced amino acid sequence of a cDNA clone of unknown function, previously isolated from a mouse astrocyte library. Sequences of mouse enhancer cDNA, obtained in the present study, predict a approximately 50-kDa, 468-amino acid protein that differs from the 43-kDa, 402-amino acid protein predicted by the previously reported astrocyte-derived clone. Human cDNAs encode an enhancer of 449 amino acids. Previous biochemical studies have found the mouse enhancer as a 55-kDa form, which is readily processed to 36- and 34-kDa forms, retaining full C-proteinase enhancing activity and the ability to bind the COOH-terminal propeptide. Data presented here show the 36-kDa form to correspond to the amino-terminal portion of the 55-kDa protein. This is the most conserved region between mouse and human enhancers, comprising two domains with homology to domains found in a number of proteases and proteins with developmental functions. Such domains are thought to mediate interactions between proteins. Mouse enhancer RNA is shown to be at highest levels in collagen-rich tissues, especially tendon. The human enhancer gene, PCOLCE, is localized to 7q21.3-->q22, the same chromosomal region containing the type I collagen alpha 2 chain gene, COL1A2.

Amino Acid Sequence↗
PubMed1994

Fine structure analysis of the WT1 gene in sporadic Wilms tumors.

Molecular genetic studies indicate that the etiology of Wilms tumor (WT) is complex, involving at least three loci. Germ-line mutations in the tumor suppressor gene, WT1, have been documented in children with WTs and urogenital developmental anomalies. Sporadic tumors constitute the majority (> 90%) of WT cases and previous molecular analyses of the WT1 gene have focused only on the DNA-binding domain. Using the single-strand conformational polymorphism (SSCP) assay, we analyzed the structural integrity of the entire WT1 gene in 98 sporadic WTs. By PCR-SSCP we find that mutations in the WT1 gene are rare, occurring in only six tumors analyzed. In one sample, two independent intragenic mutations inactivated both WT1 alleles, providing a singular example of two different somatic alterations restricted to the WT1 gene. This case is consistent with the existence of only one tumor suppressor gene at 11p13 involved in the pathogenesis of WTs. Our data, together with the previously ascertained occurrence of large deletions/insertions in WT1, define the frequency at which the WT1 gene is altered in sporadic tumors.

Amino Acid Sequence↗
PubMed1994

Human, mouse, and rat calnexin cDNA cloning: identification of potential calcium binding motifs and gene localization to human chromosome 5.

Calnexin is a 90-kDa integral membrane protein of the endoplasmic reticulum (ER). Calnexin binds Ca2+ and may function as a chaperone in the transition of proteins from the ER to the outer cellular membrane. We have purified human calnexin in association with the human interferon-gamma receptor and cloned calnexin cDNA from placenta. Fragments of calnexin have been prepared as glutathione S-transferase fusion proteins and analyzed for their abilities to bind 45Ca2+ and ruthenium red. A subdomain containing four internal repeats binds Ca2+ with the highest affinity. This sequence is highly conserved when compared to calreticulin (a luminal ER protein), an Onchocerca surface antigen, and yeast and plant calnexin homologues. Consequently, this sequence represents a conserved motif for the high-affinity binding of Ca2+, which is clearly distinct from the "E-F hand" motif. An adjacent subdomain, also highly conserved and containing four internal repeats, fails to bind Ca2+. The carboxyl-terminal, cytosolic domain is highly charged and binds Ca2+ with moderate affinity, presumably by electrostatic interactions. The calnexin amino-terminal domain (residues 1-253) also binds Ca2+, in contrast to the amino-terminal domain of calreticulin, which is relatively less acidic. We have also determined the cDNA sequences of mouse and rat calnexins. Comparison of the known mammalian calnexin sequences reveals very high conservation of sequence identity (93-98%), suggesting that calnexin performs important cellular functions. The gene for human calnexin is located on the distal end of the long arm of human chromosome 5, at 5q35.

Amino Acid Sequence↗
PubMed1994

A human amphotropic retrovirus receptor is a second member of the gibbon ape leukemia virus receptor family.

Retrovirus infection is initiated by binding of the viral envelope glycoprotein to a cell-surface receptor. The envelope proteins of type C retroviruses of mammals demonstrate similarities in structural organization and protein sequence. These similarities suggest the possibility that retroviruses from different interference groups might use related proteins as receptors, despite the absence of any relationship between retrovirus receptors isolated to date. To investigate this possibility, we have identified a human cDNA clone encoding a protein closely related to the receptor for gibbon ape leukemia virus and have found that it functions as the receptor for the amphotropic group of murine retroviruses. Expression of this protein (GLVR-2) is likely to be a requirement for infection of human cells by amphotropic retroviral vectors for purposes of gene therapy.

3T3 Cells↗