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Biomedical subjects

G Gachelin

Publications and source records attributed to G Gachelin.

At least 73 records · Page 4Linked to original sources
PubMed1991

MHC gene Q8/9d of the BALB/cJ mouse strain cannot encode a Qa-2,3 class I antigen.

We have determined the nucleotide sequence of Q8/9d gene of the BALB/c strain of mice, isolated from Steinmetz's cosmid library. As for all other class I genes of the Qa region, the Q8/9d gene spans approximately 4.7 kilobases (kb) and consists of seven exons and six introns. A seven bases deletion in exon 3 results in the occurrence of an early termination codon. Thus the Q8/9d gene cannot encode a normal class I protein. Comparison of the nucleotide sequence of the Q8/9d gene with that of other class I MHC genes revealed a stronger homology to Q7 and Q8 than to K, D, L, TL, and other Q genes. However, the gene cannot originate from a mere fusion between Q8 and Q9 genes except if the ancestor to putative Q8d was markedly different from the present Q8b gene. Using polymerase chain reaction (PCR) technology, we have confirmed the presence of a Q8/9 gene, identical to that present in cosmid 46.1, in the genome of BALB/cJ (Qa-2low). Finally, it has been reported that cDNA clone 94-A, which codes for a Qa-2 antigen, could derive from a transcript of gene Q8/9d. The nucleotide sequences of gene Q8/9d and of cDNA clone 94-A are distinctly different in their 5' regions, in spite of an almost perfect matching in their 3' regions. Thus, clone 94-A cannot derive from an mRNA transcribed from the Q8/9d gene.

Animals↗
PubMed1990

Comparison of the promoter regions of H-2Kb and H-2Kbm1 class I MHC genes.

The 2.0 kb-long nucleotide sequences of the promoter regions of two closely related class I genes of the mouse major histocompatibility complex (H-2Kb and H-2Kbm1) have been determined and compared. The promoter sequence of the H-2Kbm1 gene differs from that of the H-2Kb gene by a single deletion of a 'C' at position -456 in the upstream region of H-2Kbm1 gene. The actual existence of this deletion of a single base in genomic DNA has been verified by genomic DNA hybridization, using oligonucleotide probes specific for H-2Kbm1 or H-2Kb respectively. The effect on the enhancer activity of H-2Kbm1 promoter region of the difference at position -456 has been analyzed by the chloramphenicol acetyltransferase (CAT) assay, using appropriate DdeI fragments (-533 to -408 for H-2Kbm1; -534 to -408 for H-2Kb) cloned downstream of pH-2(367)CAT gene construct. The CAT activity determined by the H-2Kbm1 fragment was about 3-fold higher than that of H-2Kb, a result which probably accounts for the higher level of the H-2Kbm1 transcript and antigen in lymph node cells.

Animals↗
PubMed1990

Comparative structure of two duplicated T1a class I genes (T10c and 37) of the murine H-2d MHC. Implications on the evolution of the T1a region.

The class I Ag encoded in the Qa/T1a regions of the murine MHC are much less polymorphic, and usually have a more restricted tissue distribution than the classical histocompatibility class I Ag, encoded by genes located in the H-2K, D, and L loci. The isolation of a quasi-ubiquitously expressed, poorly polymorphic class I gene of the T1a region of the H-2d mouse MHC, namely gene 37 (or T18d), has been recently reported. We describe the nucleotide sequence of a closely related gene, T10c gene, the counterpart of the gene 37 in the large duplicated parts of T1a region of the BALB/c (H-2d) MHC. The T10c gene structure and sequence are very similar to those of gene 37, but T10c gene is most likely a pseudogene. In A/J mouse strain, there appears to be a single gene related to 37, which is also found expressed in a variety of tissues. We show that this gene is likely to be a chimeric one derived from T10c for its 3' part, and from a gene closely related to gene 37 for its 5' part, which potentially encodes for an unusual class I molecule composed of the first two domains. Finally, Southern blot analysis of a number of wild mice and related animals suggests that a gene closely related to the present T10c gene may be the ancestor of this subfamily of class I genes characterized by the presence of an unusual second domain.

Animals↗
PubMed1990

Identification of sequences responsible for positive and negative regulation by E1A in the promoter of H-2Kbm1 class I MHC gene.

The mechanism of transcriptional regulation of the H-2Kbm1 major histocompatibility complex (MHC) class I gene by adenovirus type 12 E1A (Ad12-E1A) was studied in transfected rat embryonal fibroblasts. Results of long-term expression of the chloramphenicol acetyl transferase (CAT) gene placed under the control of the 5'-flanking region of the mouse MHC class I gene. H-2Kbm1, and the results of nuclear run-on transcription assays, yield evidence for both positive and negative regulation of H-2Kbm1 by E1A gene product. Deletion studies in the H-2Kbm1 promoter region revealed that a proximal 58 bp upstream sequence (-194 to -136, relative to the cap site) and a distal 316 bp sequence (-1837 to -1521) respectively contribute to positive and negative regulation mediated by the E1A gene product. Both regulatory elements of MHC class I gene promoter region are responsible for the differential expression of the H-2Kbm1 gene in Ad12 transformed cells. A nuclear factor binding to the negative element has been detected only in extracts derived from cells expressing Ad12-E1A.

Adenovirus Early Proteins↗
PubMed1988

Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes.

We have examined the phylogenetic distribution of two t-specific markers among representatives of various taxa belonging to the genus Mus. The centromeric TCP-1a marker (a testicular protein variant specific for all t-haplotypes so far studied) has also been apparently detected in several non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor species. By contrast, a t-specific restriction-fragment-length polymorphism allele (RFLP) of the telomeric alpha-globin pseudogene DNA marker alpha-psi-4 was found only in animals belonging to the M. musculus-complex species either bearing genuine t-haplotypes or, like the M. m. bactrianus specimen studied here, likely to do so. This t-specific alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or M. spretus ones. These results suggest the presence of t-haplotypes and of t-specific markers in populations other than those belonging to the M. m. domesticus and M. m. musculus subspecies, implying a possible origin for t-haplotypes prior to the radiation of the most recent offshoot of the Mus genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.

Animals↗
PubMed1987

Spontaneous autocytotoxicity against an unexpected H-2d haplotype in MRL/lpr (H-2k) autoimmune disease-prone mice.

The MRL/lpr (H-2k) inbred strain, a model for the autoimmune disease systemic lupus erythematosus, differs from the healthy inbred strain MRL +/+ (H-2k) by only 0.1% of its genome. Southern blot analysis using class I and class II probes confirmed the H-2k genotype of both strains. Among the Iak-positive peritoneal cells, cells with an unexpected expression of Iad specificities were detected in a radioimmunoassay using several monoclonal antibodies and one conventional antiserum. This was only found in aged (6- to 9-month-old) mice both in the MRL/lpr strain (32% Iad-positive mice) and in the MRL +/+ strain (42% Iad-positive mice). Furthermore, 24% of aged MRL/lpr mice exhibited strong spontaneous cytotoxic T lymphocyte (CTL) activities against P815 (H-2d) target cells, and 57% had a weaker but still detectable level of cytotoxicity. In contrast, such a CTL activity has never been found in the MRL +/+ strain. These results suggest that the anti-H-2d CTL plays a role in the onset of the autoimmune process in MRL/lpr mice.

Animals↗
PubMed1987

Tissue-specific expression of the mouse Q10 H-2 class-I gene during embryogenesis.

We have studied the pattern of expression of the Q10 gene, a H-2 class-I gene located in the major histocompatibility complex which encodes a soluble class-I molecule, in the mid-gestation mouse embryo, and compared it to those of two other class-I genes, namely Kd and 37, the latter gene located in the thymus leukemia region. We found that the steady-state amount of these different mRNAs gradually increased from day 13 to day 18. By comparison with the level of expression of these genes in adult liver, the increase during gestation was fairly more marked for Q10 mRNA than for the others. Furthermore, we found that the Q10 gene is transiently expressed in the endoderm layer of the visceral yolk sac and in the fetal heart. Expression in the latter tissue decreases abruptly while increasing in the liver. It has been proposed that the Q10 protein is involved in immune tolerance. However, the time course of expression of Q10 mRNA and its tissue distribution during embryogenesis suggest that the Q10 protein could play a role in the differentiation of hematopoietic stem cells.

Animals↗
PubMed1985

An H-2K gene of the tw32 mutant at the T/t complex is a close parent of an H-2Kq gene.

Two recombinant mice have been recovered from the progeny of Ttf/tw32 + animals. They have lost the tw32 lethality factor(s) and gained tufted, presumably from the T chromosome. Southern blot analysis of class I genes of these two new partial tPA027 and tPA286 haplotypes indicates that they have retained at least part of the major histocompatibility complex of the tw32 chromosome (H-2 haplotype H-2w28). We have prepared a phage library of Eco RI-digested DNA from homozygous tPA027 animals. Upon screening the library with a cDNA probe specific for H-2K genes, we isolated a class I gene displaying all of the distinctive features of a genuine H-2K gene, and which could thus be defined as an H-2Kw28 gene. The H-2Kw28 gene is 92-95% homologous to H-2Kb and H-2Kd genes and differs significantly from the other class I genes sequenced so far. Homology with the H-2Kb sequence reaches nearly 100% in the 3' part of the H-2Kw28 gene. Moreover, the homology with an H-2Kq cDNA sequence reaches 99.8%. Several hypotheses can account for the near identity of H-2Kb, H-2Kq, and H-2Kw28 gene sequences: either recombination between H-2w28 and H-2b and H-2q sequences occurred before or at the time the strain was established, or the class I genes of the tw32 chromosome and the H-2b and H-2q genes found in inbred strains of mice have separated from each other rather recently.

Amino Acid Sequence↗
PubMed1984

1H-NMR spectroscopy of the glycoprotein-bound large carbohydrates from embryonal carcinoma cells.

400 MHz NMR spectrum was recorded for the glycoprotein -bound large carbohydrates (embryoglycan) isolated from F9 embryonal carcinoma cells. Two intense signals at 4.13 ppm and 4.69 ppm were assigned to be H-4 of galactosyl residues substituted at C-3 and H-1 of G1cNAc beta 1----3, respectively. The result is consistent with the proposal that the fundamental building unit of the large glycan is G1cNAc beta 1----3Ga1 beta. Furthermore, the spectral data confirmed a conclusion obtained by glycosidase digestion that fucosyl residues are linked mostly to N-acetylglucosamine rather than galactose.

Carbohydrate Sequence↗
PubMed1983

Different exon-intron organization at the 5' part of a mouse class I gene is used to generate a novel H-2Kd-related mRNA.

A cDNA library constructed from liver mRNA of DBA/2 (H-2d) mice has been screened with H-2-specific probes. The nucleotide sequence of one clone (pH-2d-24) indicates that it derives from an H-2 gene with an unexpected exon-intron organization. Nucleotide sequence comparisons suggest that two distinct mRNAs are produced from a single H-2Kd gene by a mechanism involving the use of alternative splicing sites in its 5' region. pH-2d-24 carries an open reading frame encoding a thus-far-undescribed polypeptide product identical to an H-2Kd-molecule, except for the NH2-terminal half of the first domain.

Amino Acid Sequence↗
PubMed1983

Glycoprotein-bound large carbohydrates of early embryonic cells: structural characteristic of the glycan isolated from F9 embryonal carcinoma cells.

The high-molecular-weight glycopeptides characteristic of early embryonic cells were isolated from F9 embryonal carcinoma cells grown in vitro and also from the cells grown in vivo as subcutaneous tumors. The two preparations had similar carbohydrate compositions. The major components were galactose and N-acetylglucosamine (molar ratio 1:0.86) in the glycan isolated from the cultured cells. In addition, small amounts of fucose, N-acetylgalactosamine and mannose were present. The glycan from the in vitro grown cells was found to have a molecular weight of more than 10,000 by gel filtration after mild alkaline treatment or hydrazinolysis. The structural characteristics of the core portion of the glycan were studied by using the radioactively labeled glycopeptide from the in vitro grown cells. Methylation analysis provided the following informations. 1) The glycan was highly branched at galactosyl residues. 2) Large numbers of galactosyl residues were also present at non-reducing termini. 3) Monosubstitution of galactose occurred at C-3. 4) Glucosamine residues were mainly monosubstituted. That the disaccharide GlcNAc-Gal was the major structural unit of the glycan was suggested by the isolation of the deacetylated disaccharide after alkaline thiophenol cleavage followed by acid hydrolysis. Furthermore, methylation analysis of the glycan from the in vivo grown tumors indicated that monosubstitution of glucosamine occurred at C-4 and that disubstitution of galactose occurred at least mainly at C-3 and C-6. We propose that the basic structural unit of the core portion is 4GlcNAc 1 leads to 3Gal, and that the galactosyl residue serves as a branching point at C-6. Thus, the structural unit of the core portion of the large glycan appears to be the same as that of lactosaminoglycans found in adult cells.

Amino Acids↗
PubMed1982

Comparison of nucleotide sequences of mRNAs belonging to the mouse H-2 multigene family.

The complete nucleotide sequences of three cDNAs coding for the C-terminal part of mouse histocompatibility (H-2) antigens, and for the 3' non coding regions of these clones have been determined. Comparison of the sequence indicates a large homology throughout the coding and non-coding regions and suggests the existence of a genetic mechanism which homogenizes nucleotide sequences among genes of the H-2 multigene family.

Amino Acid Sequence↗
PubMed1981

cDNA clone coding for part of a mouse H-2d major histocompatibility antigen.

mRNA coding for mouse major transplantation antigens of the d haplotype was partially purified, copied into double-stranded cDNA, and cloned in Escherichia coli. Clones were selected by their ability to hybridize specifically with mRNA coding for H-2K, D, or L antigens. One of these clones, pH-2d-1, carries a 1200-base-pair insert, comprising the noncoding region, including poly(A) at the 3' end and part of the coding region. A partial sequence of the latter region showed extensive homology with the known amino acid sequences of H-2Kb,Kk, and HLA-B7 antigens. From this comparison, it appears that the coding region extends from amino acid 133 in the second domain, through the third domain, to the cytoplasmic COOH-terminal region. A stretch of 24 hydrophobic or uncharged residues, located 31 amino acids from the COOH-terminal end, could represent the segment that spans the membrane. This is followed on the cytoplasmic side of the membrane by a cluster of basic amino acids and a possible phosphorylation site on a threonine residue.

Amino Acid Sequence↗
PubMed1980

Serological identification and cellular distribution of three F9 antigen components.

Using an affinity chromatography technique, IgM, IgG1, IgG2a,b anti-F9 antibodies have been isolated from the anti-F9 serum; their activities have been analyzed by IF test on a variety of cell types, teratocarcinoma-derived cell lines, and embryos. The anti-F9 antibodies react with at least three independent antigenic determinants not expressed on the same cell types, and that appear along different time-course during embryonic development.

Animals↗