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C L Hsieh

Publications and source records attributed to C L Hsieh.

At least 91 records · Page 5Linked to original sources
PubMed1992

Transient immunoglobulin M antibody response to hepatitis C virus capsid antigen in posttransfusion hepatitis C: putative serological marker for acute viral infection.

The development of serological assays for hepatitis C virus (HCV) has made specific diagnosis possible. However, markers useful in indicating acute-phase HCV infection have not been identified. By an immunoblotting method, we characterized the IgM and IgG antibody response against HCV capsid antigen in patients with HCV infection. Among 88% of patients with acute posttransfusion hepatitis C recruited in a prospective study, there was a transient IgM antibody response. The IgM antibody appeared shortly after onset of hepatitis (average 3.7 weeks), persisted for several months (average 18 weeks), and then disappeared. In contrast, the IgG antibody persisted long-term once it appeared. Among patients with chronic hepatitis C with milder disease activities (serum aminotransferase increase above normal levels of less than 4-fold), the IgM antibody was negative in the majority (72%). In those with acute exacerbations (aminotransferase increase of greater than 10-fold), about 55% were negative for the IgM antibody. The reactivity of the IgM antibody in the rest was weaker or became negative upon further dilution of serum. The results suggest that IgM anti-capsid antibody may serve as a marker indicating acute or active HCV infection.

Acute Disease↗
PubMed1992

Improved gene expression by a U3-based retroviral vector.

To improve the expression of the genes transduced by retroviral vectors, we have constructed a U3-based retroviral vector and evaluated its effect on the expression of an insert from the internal promoter. The unique feature of the vector is that the transduced gene is inserted at the U3 region of the 3' long terminal repeats (LTR). Consequently, in the infected cells the gene is duplicated and transferred to the 5'-LTR. When compared with the conventional retroviral vectors which insert the gene within the retroviral transcriptional unit, the U3-based vectors greatly enhanced the expression of the transduced gene under all three promoters tested, viz. the cytomegalovirus immediately early gene promoter (CMV), the SV40 early gene promoter (SV), and the herpes simplex virus thymidine kinase gene promoter (TK). The SV and TK promoters which were previously shown suppressed by the retroviral promoter in the conventional construction restored their potencies in the U3-based vectors. Our results therefore suggested that the U3-based vectors are more advantageous than the conventional vectors for gene expression.

Animals↗
PubMed1992

CpG methylated minichromosomes become inaccessible for V(D)J recombination after undergoing replication.

The physical parameters controlling the accessibility of antigen receptor loci to the V(D)J recombination activity are unknown. We have used minichromosome substrates to study the role that CpG methylation might play in controlling V(D)J recombination site accessibility. We find that CpG methylation decreases the V(D)J recombination of these substrates more than 100-fold. The decrease correlates with a considerable increase in resistance to endonuclease digestion of the methylated minichromosome DNA. The minichromosomes acquire resistance to both the intracellular V(D)J recombinase and exogenous endonuclease only after DNA replication. Therefore, CpG methylation specifies a chromatin structure that, upon DNA replication, is resistant to eukaryotic site-specific recombination. These findings are important to V(D)J recombination as well as to the chromatin assembly of methylated DNA during replication.

Animals↗
PubMed1992

Induced reciprocal translocation in transgenic mice near sites of transgene integration.

Transgenic mice (JCP0 #18), heterozygous for an insertion of approximately 50 copies of the rat peripheral myelin (P0) protein cDNA, displayed a pattern of reduced litter size that suggested a chromosome rearrangement. Chromosome banding studies of fetal cells disclosed the presence of an apparently balanced translocation between a Chromosome (Chr) 1 and 14 with breakpoints at bands 1H3 and 14C3. In situ hybridization of biotin-labeled P0 rat cDNA probe to chromosome spreads and detection of specific signal with fluorescein isothiocyanate-conjugated avidin revealed a strong signal on the 1(14) translocation chromosome at the site of the breakpoint. A weaker signal was present near the breakpoint on the 14(1) derivative chromosome. These results suggest an etiologic relationship between the insertion of the transgene and the origin of the translocation. To further elucidate possible mechanisms, we first mapped the endogenous P0 gene (gene symbol Mpp). As previously reported (You et al., Genomics 9: 751, 1991), we found that Mpp is located on Chr 1 in the region of the translocation breakpoint in JCP0 mice. Subsequently, we have carried out pulsed-field gel and standard Southern analyses with P0 gene probes, but found no evidence for a direct involvement of the endogenous P0 gene in the process that generated the balanced reciprocal translocation. Thus, we favor the hypothesis that, during repair of DNA strand breakage--possibly induced by the microinjection procedure--the transgene copies were ligated to broken ends of Chrs 1 and 14. According to convention, this translocation is designated T(1;14)1Po. Homozygotes are phenotypically normal and breed well; they will be useful for genetic and physical mapping of Chrs 1 and 14.

Animals↗
PubMed1992

Serotonin receptor 1c gene assigned to X chromosome in human (band q24) and mouse (bands D-F4).

In the mammalian nervous system, serotonin (5-hydroxytryptamine) binds to distinct cell surface receptor subtypes that are defined by their ligand binding and effector-coupling properties. The 5HT1c receptor is a G-protein coupled receptor that stimulates phospholipase C-catalyzed hydrolysis of phosphatidylinositol bisphosphate, leading to the mobilization of intracellular calcium and to the activation of protein kinase C. By using somatic cell hybrid analysis and FISH, we have mapped the HTR1C locus to the human X chromosome, band q24 and to the mouse X chromosome region D-F4. Comparison of these map positions offers new insights into the evolution of human and murine X chromosomes. Since HTR1C is expressed in certain parts of the central nervous system and abnormal function of the serotoninergic system has been implicated in affective disorders, obsessive-compulsive disorder and epilepsy, establishing the precise map position of HTR1C is an important first step toward evaluating this locus as a candidate for mutations in these syndromes and in X-linked mental disorders.

Animals↗
PubMed1992

Mitochondrial and nuclear variants in a U.S. black population: origins of a hybrid population.

The maternal transmission of mitochondria in higher eukaryotes makes it possible to distinguish between reciprocal matings, since offspring possess the mitochondrial DNA variants received from the mother. This possibility can be extended to hybrid populations, the mitochondrial frequencies reflecting the relative maternal contributions from the parental populations. Nuclear variations reflect the relative genetic contributions of the parental populations, irrespective of parental sex. The U.S. Black population is a hybrid of West African and European populations. The African-European matings that contributed to the present Black population are traditionally considered to have been almost exclusively between African females and European males. We have studied nuclear and mitochondrial variants in a sample of U.S. Blacks, comparing them with published frequencies from African and Caucasian groups. Our results suggest that the mitochondria of present-day American Blacks are derived from Caucasians to an extent similar to nuclear genes. In contrast to traditional beliefs, the contribution from Caucasian females is of the same magnitude as that from Caucasian males.

Adult↗
PubMed1992

Analysis of the defect in DNA end joining in the murine scid mutation.

Murine severe combined immune deficiency (scid) is marked by a 5,000-fold reduction in coding joint formation in V(D)J recombination of antigen receptors. Others have demonstrated a sensitivity to double-strand breaks generated by ionizing radiation and bleomycin. We were interested in establishing the extent of the defect in intramolecular and intermolecular DNA end joining in lymphoid and nonlymphoid cells from scid mice. We conducted a series of studies probing the ability of these cells to resolve free ends of linear DNA molecules having various biochemical end configurations. We find that the stable integration of linear DNA into scid fibroblasts is reduced 11- to 75-fold compared with that in normal fibroblasts. In contrast, intramolecular and intermolecular end joining occur at normal frequencies in scid lymphocytes and fibroblasts. This normal level of end joining is observed regardless of the type of overhang and regardless of the requirement for nucleolytic activities prior to ligation. The fact that free ends having a wide variety of end configurations are recircularized normally in scid cells rules out certain models for the defect in scid. We discuss the types of DNA end joining reactions that are and are not affected in this double-strand break repair defect in the context of a hairpin model for V(D)J recombination.

Animals↗
PubMed1992

Localization of the photoreceptor gene ROM1 to human chromosome 11 and mouse chromosome 19: sublocalization to human 11q13 between PGA and PYGM.

Rom-1 is a retinal integral membrane protein that, together with the product of the human retinal degeneration slow gene (RDS), defines a photoreceptor-specific protein family. The gene for rom-1 (HGM symbol: ROM1) has been assigned to human chromosome 11 and mouse chromosome 19 by Southern blot analysis of somatic cell hybrid DNAs. ROM1 was regionally sublocalized to human 11p13-11q13 by using three mouse-human somatic cell hybrids; in situ hybridization refined the sublocalization to human 11q13. Analysis of somatic cell hybrids suggested that the most likely localization of ROM1 is in the approximately 2-cM interval between human PGA (human pepsinogen A) and PYGM (muscle glycogen phosphorylase). ROM1 appears to be a new member of a conserved syntenic group whose members include such genes as CD5, CD20, and OSBP (oxysterol-binding protein), on human chromosome 11 and mouse chromosome 19. Localization of the ROM1 gene will permit the examination of its linkage to hereditary retinopathies in man and mouse.

Animals↗
PubMed1991

Genomic organization and chromosomal localization of the TAPA-1 gene.

TAPA-1 is a 26-kDa integral membrane protein expressed on many human cell types. Antibodies against TAPA-1 induce homotypic aggregation of cells and can inhibit their growth. The murine homologue of TAPA-1 was cloned from both cDNA and genomic DNA libraries. A very high level of homology was found between human and mouse TAPA-1. The 5' untranslated region of the TAPA-1 gene resembles housekeeping gene promoters with respect to G + C content and the presence of potential Sp1 binding sites. The chromosomal localization of human and murine TAPA-1 genes was determined by Southern blot experiments using DNA from somatic cell hybrids. The genes were found to be part of a conserved syntenic group in mouse chromosome 7 and the short arm of human chromosome 11. The organization of the TAPA-1 gene and the projection of the exon boundaries on the proposed protein structure are presented.

Amino Acid Sequence↗
PubMed1991

Mutations in the bile acid biosynthetic enzyme sterol 27-hydroxylase underlie cerebrotendinous xanthomatosis.

The sterol storage disorder cerebrotendinous xanthomatosis (CTX) is characterized by abnormal deposition of cholesterol and cholestanol in multiple tissues. Deposition in the central nervous system leads to neurological dysfunction marked by dementia, spinal cord paresis, and cerebellar ataxia. Deposition in other tissues causes tendon xanthomas, premature atherosclerosis, and cataracts. In two unrelated patients with CTX, we have identified different point mutations in the gene (CYP27) encoding sterol 27-hydroxylase, a key enzyme in the bile acid biosynthesis pathway. Transfection of mutant cDNAs into cultured cells results in the synthesis of immunoreactive sterol 27-hydroxylase protein with greatly diminished enzyme activity. We have localized the CYP27 gene to the q33-qter interval of human chromosome 2, and to mouse chromosome 1, in agreement with the autosomal recessive inheritance pattern of CTX. These findings underscore the essential role played by sterols in the central nervous system and suggest that mutations in other sterol metabolizing enzymes may contribute to diseases with neurological manifestations.

Animals↗
PubMed1991

Identity of human Lyb-2 and CD72 and localization of the gene to chromosome 9.

We have recently reported the isolation of cDNA clones encoding the human homolog of the mouse B cell differentiation antigen Lyb-2. Expression of Lyb-2 is restricted to B lineage cells and turned off in antibody-secreting plasma cells in both mice and humans. Functional studies with anti-mouse Lyb-2 monoclonal antibodies (mAb) suggest that this protein may be involved in signals for B cell proliferation. We now describe the generation of mAb specific for human Lyb-2. Furthermore, we demonstrate that the human Lyb-2 protein is recognized by a mAb specific for the newly clustered pan B cell surface antigen CD72, which had been defined by mAb. Mouse L(tk-) cells expressing a transfected cDNA encoding human Lyb-2 bind a mAb specific for CD72. We further show that an antiserum and a mAb specific for human Lyb-2 and an anti-CD72 mAb immunoprecipitate the identical protein from human splenic B cells and B cell lines, as well as from transfected L(tk-) cells. These data indicate that CD72 is the human equivalent of mouse Lyb-2. We have additionally localized the gene for human Lyb-2/CD72 on the short arm of chromosome 9. Mouse Lyb-2 had been previously mapped to mouse chromosome 4. Lyb-2/CD72 is now the tenth gene known to be localized on human chromosome 9 and mouse chromosome 4.

Animals↗
PubMed1991

Distribution of genes for gap junction membrane channel proteins on human and mouse chromosomes.

Gap junctions are widely distributed structures that mediate communication between cells. The channels that allow passage of small molecules between adjacent cells are made up of oligomeric proteins (connexins) that are encoded by a family of related genes. By probing somatic cell hybrid DNA on Southern filters with rat or human cDNAs or human genomic fragments, we have mapped four functioning gap junction genes, (alpha 1, beta 1, beta 2, and alpha 3), to different sites on human chromosomes: GJA1 (connexin43) to 6p21.1-q24.1; GJB1 (connexin32) to Xcen-q22; GJB2 (connexin26) to 13; and GJA3 (connexin46) also to 13, probably near GJB2. The GJA3 probe also hybridized to a restriction fragment that was mapped to chromosome 1. A GJA1-related pseudogene GJA1P was assigned to chromosome 5. The homologous loci in mouse were assigned to regions of known conserved syntenic groups: Gja-1 to chromosome 10; Gjb-1 to XD-F4 and Gjb-2 to 14. Of two sites of hybridization with the GJA3 probe, on mouse 14 and 5, we assume that the site on 14 corresponds to the GJA3 locus on human 13. Based on these data, additional members of this family of related genes can be isolated and characterized, and possible human and mouse mutations can be identified.

Animals↗
PubMed1991

Sequence analysis, expression and chromosomal localization of a gene, isolated from a subtracted human retina cDNA library, that encodes an insulin-like growth factor binding protein (IGFBP2).

The metabolic functions of insulin-like growth factors (IGFs) I and II are modulated by a family of binding proteins which are present in biological fluids and are synthesized by a variety of cell types. A cDNA clone, isolated at random from a subtracted human retina library, has been identified to code for a novel IGF-binding protein (IGFBP2) by its sequence homology to the peptide sequence of IGF binding proteins purified from bovine MDBK and rat BRL-3A cells. The complete nucleotide sequence of the IGFBP2 cDNA is 1406 bp long, contains 66% G-Cs and an open reading frame of 328 amino acids with a putative signal or pro-peptide of 39 residues. The mature polypeptide of 289 amino acids has 18 cysteines, a putative ATP-binding site and an RGD tripeptide. The 1.4 kb IGFBP2 transcript is expressed in several human tissues including fetal eye and fetal brain, but not in the human lymphoblastoid cell line against which the retinal cDNA library was subtracted. In situ hybridization to sections of mouse retina localized the mRNA for IGFBP2 primarily in the outer nuclear layer of photoreceptors. Southern blot analysis of DNA from human x rodent and mouse x rodent somatic cell hybrids assigned the gene for IGFBP2 to human chromosome 2q33-qter and mouse chromosome 1 in a known conserved syntenic region.

Aged↗
PubMed1991

Characterization and chromosomal mapping of a human steroid 5 alpha-reductase gene and pseudogene and mapping of the mouse homologue.

The enzyme steroid 5 alpha-reductase catalyzes the conversion of testosterone into the more powerful androgen, dihydrotestosterone. We previously described the cloning of rat and human cDNAs that encode steroid 5 alpha-reductase and their expression in oocytes and cultured cells. Here, we report the isolation, characterization, and chromosomal mapping of two human steroid 5 alpha-reductase genes. One gene (symbol SRD5A1) is functional, contains five exons separated by four introns, and maps to the distal short arm of chromosome 5. Two informative restriction fragment length polymorphisms are present in exons 1 and 2 of this gene. A second gene (symbol SRD5AP1) has all of the hallmarks of a processed pseudogene and was mapped to the q24-qter region of the X chromosome. In the mouse, a single steroid 5 alpha-reductase gene (Srd5 alpha-1) is linked to Xmv-13 on chromosome 13.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1991

cDNA and genomic cloning of HRC, a human sarcoplasmic reticulum protein, and localization of the gene to human chromosome 19 and mouse chromosome 7.

Histidine-rich calcium binding protein (HRC) is a luminal sarcoplasmic reticulum (SR) protein of 165 kDa identified by virtue of its ability to bind 125I-labeled low-density lipoprotein with high affinity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Hofmann et al., J. Biol. Chem. 264: 8260-8270, 1989). Its role in SR function is unknown. In this report, the gene encoding human HRC was localized to human chromosome 19 and mouse chromosome 7 by hybridization of a human HRC cDNA fragment to a panel of somatic cell hybrids. Known synteny between a portion of human chromosome 19 and a portion of mouse chromosome 7 and in situ hybridization of a biotin-labeled HRC probe to human chromosomes suggest a localization to a region corresponding to 19q13.3. The locus for myotonic dystrophy resides in the region 19q13.2-13.3. Therefore, we considered HRC, a muscle-specific gene, to possibly represent a "candidate gene" for myotonic muscular dystrophy. As a first step toward localizing HRC in relation to the myotonic dystrophy locus, we report the cloning of the human HRC gene, its intron-exon organization, and characterization of several informative polymorphisms to be used in future linkage studies in families with myotonic dystrophy. Of particular interest is an Alu-associated poly-d(GA) sequence located in an intron in the middle of the gene, and two stretches of acidic amino acids in the coding region of exon 1 that vary in length among different individuals.

Amino Acid Sequence↗
PubMed1991

DNA sequence, genomic organization, and chromosomal localization of the mouse peripheral myelin protein zero gene: identification of polymorphic alleles.

We have cloned and characterized the mouse gene, P0, that encodes the predominant protein of peripheral myelin. Similar to the rat gene, the mouse P0 gene is encoded by six exons that span about 7 kb of DNA. The DNA sequence of the mouse gene is highly homologous with the rat gene, including the regions believed to be important in transcriptional control. Furthermore, the P0 protein appears well conserved throughout evolution. The gene was mapped to mouse chromosome 1 by Southern analysis of a Chinese hamster x mouse somatic cell hybrid panel. Several polymorphic restriction enzyme sites were identified within the P0 locus. Recombinant inbred strain mapping has linked the P0 gene to Ly-9/Ly/Sap in a region corresponding to band 1H3.

Alleles↗
PubMed1991

Structure of the human cytochrome c oxidase subunit Vb gene and chromosomal mapping of the coding gene and of seven pseudogenes.

Subunit Vb of mammalian cytochrome c oxidase (COX; EC 1.9.3.1) is encoded by a nuclear gene and assembled with the other 12 COX subunits encoded in both mitochondrial and nuclear DNA. We have cloned the gene for human COX subunit Vb (COX5B) and determined the exon-intron structure by both hybridization analysis and DNA sequencing. The gene contains five exons and four introns; the four coding exons span a region of approximately 2.4 kb. The 5' end of the COX5B gene is GC-rich and contains many HpaII sites. Genomic Southern blot analysis of human DNA probed with the human COX Vb cDNA identified eight restriction fragments containing COX Vb-related sequences that were mapped to different chromosomes with panels of human x Chinese hamster somatic cell hybrids. Because only one of these fragments hybridized with a 210-bp probe from intron 4, we conclude that there is a single expressed gene for COX subunit Vb in the human genome. We have mapped this gene to chromosome 2, region cen-q13.

Amino Acid Sequence↗