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Biomedical subjects

V C Nguyen

Publications and source records attributed to V C Nguyen.

At least 37 records · Page 2Linked to original sources
PubMed1995

A new hybrid cell line containing only human chromosome 15 selected through fluorescence in situ hybridization and characterized by Alu-PCR amplification of the human DNA.

Human Cot1 DNA directly labeled with dUTP-fluorochromes (FITC, Rhodamin) and used as a probe, allowed rapid detection of one or a few human chromosomes in human-hamster hybrid cells by in situ hybridization (FISH). A hybrid cell line containing only a human acrocentric chromosome was isolated (CH35B2D). The DNA from this hybrid was used for PCR amplification with a single Alu (A33) primer. After agarose gel electrophoresis, a continuum of intense bands of between 400-700 bp was observed with A33-PCR products. No amplified product was visible with hamster DNA. FISH on normal human metaphases of biotinylated Alu-PCR products obtained with Alu A33 and compétition with human Cot1 DNA showed decoration, with high specificity for chromosome 15. It was identified after R banding obtained with PI or DAPI in an antifade adjusted to pH11 with NaOH. Under the applied conditions, the Alu (A33) products are expected to be useful for characterization, by specific decoration of chromosome 15 aberrations in pathological cells. CH35B2D could be employed for functional studies of genes located on chromosome 15.

Animals↗
PubMed1994

Structural organization and chromosomal localization of a human gene (HIP/PAP) encoding a C-type lectin overexpressed in primary liver cancer.

We previously identified, through differential screening of a human primary liver cancer library, a novel gene (named HIP) the expression of which is markedly increased in 25% of human primary liver cancers. HIP mRNA expression is tissue specific since it is restricted to pancreas and small intestine. HIP protein consists in a signal peptide linked to a carbohydrate-recognition domain (CRD), typical of C-type lectins without other binding domains. We have proposed that HIP and related proteins belong to a new family of C-type lectins. Drickamer [Drickamer, K. (1993) Curr. Opin. Struct. Biol. 3,393-400] included this group of proteins in his classification of C-type lectins as the free CRD (group VII) lectins. In the present report we describe the genomic organization and the chromosomal localization of HIP. We have shown that HIP is in fact the pancreatitis-associated protein (PAP) and provided a phylogenetic analysis of the free CRD lectins. Furthermore, the analysis of HIP/PAP gene indicates that the HIP/PAP CRD is encoded by four exons, a pattern shared with all members of this group of proteins. This common intron-exon organization indicates an ancient divergence of the free CRD-lectin group from other groups of C-type lectins. We provide evidence for the localization of HIP/PAP on chromosome 2, suggesting previous duplication of HIP/PAP and the related reg I alpha and reg I beta genes from the same ancestral gene. Finally, the sequence of the 5' upstream region of the HIP gene shows several potential regulatory elements which might account for the enhanced expression of the gene during pancreatic inflammation and liver carcinogenesis.

Amino Acid Sequence↗
PubMed1994

Assignment of the human 8.5 H gene to chromosome 5, region 5q35.

The human 8.5 H probe was isolated from a human cerebellum cDNA library with a probe corresponding to the coding region of the murine 8.5 M cDNA. This cDNA isolated from a murine cDNA library constructed from newborn cerebral hemispheres was selected because of its strong expression in embryonic neurons. Consequently the corresponding human gene could be a candidate for hereditary neurodegenerative diseases. The human 8.5 H gene was assigned by somatic hybrid analysis to chromosome 5; this chromosome contains the gene(s) for spinal muscular atrophy (SMA), a group of heritable degenerative diseases that selectively affect the anterior horn motor neuron of the spinal cord. The localization by in situ hybridization of 8.5 H on 5q35 excluded the possibility that this gene is identical to SMA. The SMA gene(s) was (were) known, from linkage analysis, to be in a region (5q11.2-q13.3) very distant from 5q35.

Animals↗
PubMed1993

Isolation of kidney complementary DNAs down-expressed in Wilms' tumor by a subtractive hybridization approach.

We applied a subtractive hybridization approach to isolate genes differentially expressed between mature kidney and Wilms' tumor. We constructed a complementary DNA library from a total mature kidney complementary DNA subtracted by an excess of mRNA from a Wilms' tumor, WAGR4, with a germline deletion of 11p13 and a somatic loss of alleles at 11p15. Six clones presenting a differential pattern of expression, positive with mRNA from the mature kidney and negative with mRNA from the Wilms' tumor WAGR4, were characterized. Among these clones were two as yet unknown expressed sequences (D11S877E and D15S109E) and four sequences from known genes: renal dipeptidase (DPEP1), alpha B-crystallin (CRYA2), uromodulin (UMOD), and plasma glutathione peroxidase (GPX2). The different patterns of expression of these genes in 11 Wilms' tumors, whether or not they are hereditary, reflect the well-documented pathogenetic heterogeneity for Wilms' tumors. We propose that these clones could be helpful for an improved histological characterization of Wilms' tumors.

Adult↗
PubMed1993

Cloning of a breakpoint cluster region at band 3q27 involved in human non-Hodgkin's lymphoma.

In a previous cytogenetic analysis, we showed the recurrence of translocations involving band 3q27 and immunoglobulin gene regions in 20 out of 319 patients with non-Hodgkin's lymphoma (NHL). We report here the molecular cloning of the translocation breakpoint from tumor cells of a patient (LAR) with t(3;14)(q27;q32) and the isolation of DNA probes which identify a major translocation cluster region (MTC) at band 3q27. A DNA library from LAR tumor cells was screened with a JH probe and several clones were identified corresponding either to a somatic rearrangement of JGH genes (V4-D2-J6-C mu clonal rearrangement) or to the t(3;14). Analysis of the t(3;14) breakpoint showed that chromosome 3 material was translocated to an inverted 14q32 VH-containing fragment which was itself translocated to the J3 gene. Chromosome 3-assigned probes were used to investigate local DNA rearrangements in a series of NHL with 3q27 translocations. Rearrangements were detected in 13 of 17 patients including 9 of 11 with t(3;14)(q27;q32), 1 of 2 with t(2;3)(p12;q27), 1 of 2 with t(3;22)(q27;q11), and 2 of 2 NHL with translocations not involving an IG gene, namely, t(3;4)(q27;p11) and t(3;7)(q27;p12). The finding of this MTC should be useful for diagnostic and prognostic studies and for the identification of a novel oncogene at band 3q27 involved in the development of B cell NHL.

Base Sequence↗
PubMed1993

A human pseudoautosomal gene encodes the ANT3 ADP/ATP translocase and escapes X-inactivation.

We report that the human ANT3 ADP/ATP translocase gene is a pseudoautosomal gene located proximal to the GM-CSF receptor alpha chain gene (CSF2RA). An ANT3-homologous locus, likely corresponding to a pseudogene, maps to chromosome 9. The ANT3 gene is transcribed from the centromere to the telomere and contains in its first intron a CpG island mapped 1300 kb from the telomere. This gene is transcribed from the Y chromosome and from the active and inactive X chromosomes. This gene thus escapes X-inactivation as predicted for genes belonging to the pseudoautosomal region.

Aneuploidy↗
PubMed1993

Rearrangements between irradiated chromosomes in three-species radiation hybrid cell lines revealed by two-color in situ hybridization.

A human-hamster hybrid cell line containing only the human X chromosome (GM06318B) was exposed to 6,000-7,000 rad of X-rays and fused with a mouse cell line (CL1D,TK-). Three radiation hybrids, LXKC40, LXKC50, and LXKC56, were selected among 39 independent clones containing human material. Two-color in situ hybridization with total genomic DNA probes (cot1 human DNA and hamster total genomic DNA) was used to analyse the irradiated chromosome rearrangements. With this three-species model system (human-hamster-mouse) and the chromosome painting process it was possible to determine the origin of each chromosomal fragment in metaphase and interphase. The results obtained indicate preferential rearrangement between irradiated human and hamster chromosomes. Whole, apparently intact hamster chromosomes were observed in all the mitoses. We suggest that these chromosomes could be neoformated from random fragments after irradiation. Hamster and human "minichromosomes" were also detected. While the integration of human material into the mouse genome was exceptional, the integration of hamster material into mouse chromosomes was more frequent. During interphase the irradiated chromosome domains were often at the periphery of the nucleus. Irradiated material protruded at the periphery of the nuclei. Micronuclei containing hamster material were detected in the vicinity of these protrusions.

Animals↗
PubMed1992

Preparation of a rat brain histidine decarboxylase (HDC) cDNA probe by PCR and assignment of the human HDC gene to chromosome 15.

The formation of histamine from its precursor histidine is catalyzed by histidine decarboxylase (HDC), a pyridoxal phosphate (PLP)-dependent decarboxylase. The knowledge of sequence similarities between various rodent HDCs permitted us to prepare a rat brain HDC cDNA probe. After reverse transcription of rat brain polyA + mRNA, the HDC cDNA obtained was amplified by the polymerase chain reaction using two specific primers. The resulting 1019-bp DNA was cloned in the p-MAL vector. Its sequence corresponds to the published data on rat fetal liver HDC. This 1019-bp rat probe detected two BamHI sequences in man; these were assigned to chromosome 15 by somatic hybrid cell analysis. According to the well-known homology between human chromosome 15 and mouse chromosome 2, the result obtained is in agreement with the published localization of HDC on mouse chromosome 2. The mapping of the human HDC gene on chromosome 15 is an original contribution to the chromosomal assignment of related PLP-dependent decarboxylases.

Animals↗
PubMed1992

Physical mapping of human loci homologous to the chicken nov proto-oncogene.

The human locus (novH) corresponding to the nov protooncogene overexpressed in avian nephroblastoma has been identified and mapped on chromosome 8q24.1. Another locus sharing homology with novH and corresponding to the connective tissue growth factor (CTGF) gene has also been mapped on chromosome 6q23.1. The chromosomal assignment of nov and CTGF proximal to c-myc and c-myb respectively is of interest because chromosomal abnormalities involving these regions have been associated with different human tumors including Wilms'.

Animals↗
PubMed1992

Mucin 4 (MUC4) gene: regional assignment (3q29) and RFLP analysis.

The use of a probe (JER64) containing a mucin 4 (MUC4) cDNA insert of 1.83 kb allowed to assign by in situ hybridization, the MUC4 gene to 3q29. This probe detected RFLPs with all restriction enzymes used (BamHI, HindIII, PstI, EcoRI, and TaqI). Particularly numerous alleles were observed with PstI, EcoRI and TaqI, in a small sample of unrelated DNAs (25 digested with PstI, 8 with EcoRI and 8 with TaqI). The PIC values were 0.69, 0.63 and 0.70 for PstI, EcoRI and TaqI respectively. The polymorphisms observed of variable number of tandem repeat (VNTR) type are in relation with the presence of tandemly repeated nucleotide sequences in MUC4 gene.

Blotting, Southern↗
PubMed1991

The human ASM (adult skeletal muscle) gene: expression and chromosomal assignment to 11p15.

A rat adult skeletal muscle probe (Asm15) originated from a rhabdomyosarcoma was used to isolate the human homologous sequence from a placenta cDNA library. Among several positive clones the longest EcoRI-EcoRI insert (ASM1) obtained was 1875 bp long with 72% homology with rat Asm15 cDNA sequence. Important variations of ASM1 RNA level were observed in different adult skeletal muscles. Expression of a 29kD ASM1 protein was demonstrated in human adult skeletal muscle lysates using an antiserum (PB1579) raised against the C terminal region of the rat Asm15 protein. The human ASM gene was assigned by somatic cell analysis with human (ASM1) and rat (Asm15) probes to chromosome 11, and by in situ hybridization with the human probe to 11p15, a chromosome region involved in human embryonal rhabdomyosarcomas. Except for the presence of a HindII restriction site, the results obtained for the restriction map and the sequence of ASM1 cDNA (data not shown) exhibited extensive homology with the human H19 DNA sequence which have been mapped with a mouse probe also in 11p15. This suggests that ASM/Asm and H19 may represent the same sequence (in this hypothesis the presence of the supplementary HindII site in our ASM1 probe is explained by polymorphic variability). However it was reported that human and mouse H19 mRNA did not encode for a protein but acted as an RNA molecule whereas in our present study ASM protein was detected in human adult skeletal muscle. This could be explained by important regulation of ASM protein expression during development and cell differentiation. However we cannot exclude for the different species studied (mouse, rat, and man) the hypothesis that H19 and ASM/Asm mRNA may represent two distinct messengers from the same gene or even from duplicated genes.

Adult↗
PubMed1991

Molecular cloning and chromosomal localization of a novel human tracheo-bronchial mucin cDNA containing tandemly repeated sequences of 48 base pairs.

A lambda gt11 cDNA library constructed from human tracheo-bronchial mucosa was screened with a polyclonal antiserum raised to chemically deglycosylated pronase glycopeptides from human bronchial mucins. Out of 20 positives clones, one partial cDNA clone was isolated and allowed to map a novel human tracheo-bronchial mucin gene. It contains 48 nucleotide tandem repeats quite perfectly identical which encodes a protein containing about 50% of hydroxy amino-acids. This clone hybridized to polydisperse messages produced by human tracheo-bronchial and human colonic mucosae. The gene (proposed name MUC 4) from which cDNA is derived maps to chromosome 3.

Amino Acid Sequence↗
PubMed1991

Relative order determination of four Yp cosmids on metaphase and interphase chromosomes by two-color competitive in situ hybridization.

Two-color competitive in situ hybridization was used to cytogenetically order four Yp cosmid probes, located in the pseudo-autosomal and TDF regions. The probes were hybridized by pairs to metaphase and interphase chromosomes. On metaphase chromosomes, determination of order between sequences separated by 3 Mb from each other was possible on a statistical basis, whereas the relative position of sequences 0.6 Mb apart could not be determined. On interphase chromosomes the complete order between sequences separated by 0.6-6 Mb was obtained rapidly by measuring the distances between two cosmid spots of every cosmid pair used in 28 to 60 nuclei. Results demonstrate the potential power of fluorescent in situ hybridization at interphase for high resolution cosmid mapping.

Binding, Competitive↗
PubMed1991

Structural features of the core proteins of human airway mucins ascertained by cDNA cloning.

Tracheobronchial secretions are one of the most important elements of the mucociliary system that protects the respiratory mucosa. They contain bronchial mucus, which is composed of a group of macromolecules secreted by the goblet cells of the epithelium and the submucosal glands. Bronchial mucins are the most characteristic molecules of this mucus. They form a group of complex, polydispersed O-linked glycoproteins containing sugars, which make up 80% of their weight. The protein core of human airway mucin has been difficult to sequence by traditional technologies because of its high content of serine and threonine residues linked to numerous oligosaccharide chains. We therefore prepared a lambda gt11 cDNA library from one sample of human tracheobronchial mucosa and screened this library with a polyclonal antibody directed against the apopeptides of human bronchial mucins. We obtained 20 positive clones that were sequenced. These sequences were classified into three different types. The use of the nucleotide probes from these clones in Northern blot analysis showed that the RNA messages were extremely polydispersed. At the current time, four of these probes allow us to map human tracheobronchial mucins genes to at least three different chromosomes. These results suggest that the peptide moiety of the human airway mucin is very heterogeneous.

Bronchi↗
PubMed1991

C-myb proto-oncogene: evidence for intermolecular recombination of coding sequences.

We have characterized a novel chicken c-myb exon whose sequences are specifically expressed in thymic cells. In situ hybridization experiments indicate that this thymus-specific coding exon is localized on a small chromosome, distinct from the large acrocentric chromosome 3 on which we recently mapped the bulk of 15 exons, common to the c-myb mRNA species expressed in hematopoietic cells of both B and T lineages. These observations indicate that intermolecular recombination is required for the tissue-specific expression of the c-myb proto-oncogene. We also show that these thymus-specific sequences are conserved in human DNA and lie on chromosome 17q25, whereas the human c-myb locus is localized on chromosome 6q22-23. Sequencing data obtained from genomic DNA and PCR analyses performed with c-myb mRNA species expressed in chicken thymic cells strongly suggest that a repeated decameric sequence plays a key role in the recombination process.

Animals↗
PubMed1990

Assignment of human tracheobronchial mucin gene(s) to 11p15 and a tracheobronchial mucin-related sequence to chromosome 13.

Extensive heterogeneity of tracheobronchial mucin RNAs has been described recently. Based on the results of total or partial cDNA sequencing, the mucin cDNAs obtained were classified into three groups. The first group contained 24 bp tandem repeat sequences, the second exhibited homology at their amino- and carboxyl-terminals, and the third group seems to consist of alternative hydrophilic-hydrophobic zones. JER58, JER47 and JER57 probes, representing the first, second, and third tracheobronchial mucin families respectively, were used for chromosome assignment. In human DNAs digested with BamHI, the JER58 probe detected a sequence of 21 kb, the JER47 probe detected a major sequence of 21 kb and a minor sequence of 4 kb, and the JER57 probe detected two sequences of 1.8 kb and 1.3 kb. By somatic hybrid cell analysis, the JER58. JER47, and JER57 major sequences were assigned to chromosome 11 and the JER47 minor sequence to chromosome 13. By in situ hybridization the JER58, JER47 and JER57 probes were assigned to 11p15. Under the experimental conditions used, no specific hybridization to the chromosome 13 region was observed with the JER47 probe. Our results indicate that tracheobronchial mucin gene(s) is/are localized on 11p15. The minor JER47 BamHI sequence localized on chromosome 13 probably corresponds to a tracheal-mucin related sequence. The intestinal mucin gene was also recently localized to the same 11p15 region. Intestinal and tracheobronchial mucins appear different according to their tissue distribution and their cDNA nucleotide sequences. Tracheal mucin probes (JER58, JER47, JER57) and intestinal probes may represent independent genes on 11p15 or else different mRNAs from the same primary transcript produced by differential splicing. Further studies using mucin genomic probes for 11p15 will be required for the elucidation of tracheal and intestinal mucin gene organisation in this region.

Animals↗