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C Rossier

Publications and source records attributed to C Rossier.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cloning of two human homologs of the Drosophila single-minded gene SIM1 on chromosome 6q and SIM2 on 21q within the Down syndrome chromosomal region.

As part of our effort to clone genes of human chromosome 21 that may contribute to Down syndrome, we have previously isolated four exons with homology to Drosophila single-minded (sim) gene, which encodes a transcription factor that is a master regulator of fruit fly neurogenesis. These exons were used to clone and characterize two human homologs of the Drosophila sim gene, SIM1 and SIM2, which map to chromosomes 6q16.3-q21 and 21q22.2, respectively; SIM2 maps within the so-called Down syndrome chromosomal region. Recently, two mouse homologs, Sim1 and Sim2, also have been identified. There is a high level of homology among human, mouse, and Drosophila sim genes in their amino-terminal half where the conserved bHLH, PAS1, PAS2, and HST domains are present. In contrast, the carboxy-terminal parts are only homologous between SIM1 and Sim1 and SIM2 and Sim2. Two isoforms (SIM2 and SIM2s) of human SIM2 have been detected that differ in their 3' ends. Northern blot analysis revealed one mRNA SIM1 species of approximately 9.5 kb and four different mRNA SIM2 species of 2.7, 3, 4.4, and 6 kb in human fetal kidney. The function of both human SIM1 and SIM2 is unknown. However, three copies of SIM2 may contribute to some specific Down syndrome phenotypes because of (1) mapping position, (2) potential function as transcriptional repressor, (3) likely dimerization with other transcription factors, (4) the temporal and spatial expression pattern of mouse Sim2, and (5) the potentially analogous role of human SIM2 to that of Drosophila sim during neurogenesis.

Amino Acid Sequence↗
PubMed1997

Identification of mutations in cystatin B, the gene responsible for the Unverricht-Lundborg type of progressive myoclonus epilepsy (EPM1).

Progressive myoclonus epilepsy (EPM1) is an autosomal recessive disorder, characterized by severe, stimulus-sensitive myoclonus and tonic-clonic seizures. The EPM1 locus was mapped to within 0.3 cM from PFKL in chromosome 21q22.3. The gene for the proteinase inhibitor cystatin B was recently localized in the EPM1 critical region, and mutations were identified in two EPM1 families. We have identified six nucleotide changes in the cystatin B gene of non-Finnish EPM1 families from northern Africa and Europe. The 426G-->C change in exon 1 results in a Gly4Arg substitution and is the first missense mutation described that is associated with EPM1. Molecular modeling predicts that this substitution severely affects the contact of cystatin B with papain. Mutations in the invariant AG dinucleotides of the acceptor sites of introns 1 and 2 probably result in abnormal splicing. A deletion of two nucleotides in exon 3 produces a frameshift and truncates the protein. Therefore, these four mutations are all predicted to impair the production of functional protein. These mutations were found in 7 of the 29 unrelated EPM1 patients analyzed, in homozygosity in 1, and in heterozygosity in the others. The remaining two sequence changes, 431G-->T and 2575A-->G, probably represent polymorphic variants. In addition, a tandem repeat in the 5' UTR (CCCCGCCCCGCG) is present two or three times in normal alleles. It is peculiar that in the majority of patients no mutations exist within the exons and splice sites of the cystatin B gene.

Amino Acid Sequence↗
PubMed1996

Cloning of a human homolog of the Drosophila enhancer of zeste gene (EZH2) that maps to chromosome 21q22.2.

To identify genes that map on human chromosome 21 (HC21) and that may contribute to the phenotype of Down syndrome (DS), exon trapping was applied to cosmid DNA from an HC21-specific library LL21NCO2-Q. More than 550 potential exons were cloned and partially characterized. One of these, hmc23b04 (GenBank X88270) showed strong homology to the Drosophila Enhancer of zeste protein (GenBank U00180) from amino acid 665 to 694 (p = 7.6 x 10(-11). We have cloned the full-length cDNA for this human homolog of the Drosophila E(z) gene (termed EZH2) and mapped it to within YACs 64f11 and 809b11 between markers D21S65 and ERG on human chromosome 21q22.2. Sequence analysis indicates that EZH2 encodes a 746-amino-acid polypeptide that shows 60.5% identity to the Drosophila E(z) protein and contains a trithorax-like domain and a DNA-binding motif. Northern blot analysis revealed that EZH2 is expressed in several tissues. Alternatively spliced mRNA species have been observed. The Drosophila E(z) protein is a member of the polycomb group genes that maintain homeotic gene repression and are thought to control gene expression by regulating chromatin. The strong sequence conservation suggests a possible function of EZH2 in regulation of gene transcription and chromatin structure; it may therefore contribute to certain phenotypes of Down syndrome by altered regulation of its target genes.

Alternative Splicing↗
PubMed1996

Cloning the cDNA of human PWP2, which encodes a protein with WD repeats and maps to 21q22.3.

We have used exon trapping to contribute to the development of the transcription map of chromosome 21q22.3 and to clone the genes responsible for disorders that map in the 21q22.3 region. Polypeptides deduced from three trapped sequences that map near PFKL showed homology to the yeast PWP2 gene. The full-length coding region of a human homologue of this yeast gene was subsequently cloned from human infant brain and fetal kidney cDNA libraries. The 919-codon open reading frame of human PWP2 belongs to the family of genes that contain tryptophan-aspartate (WD) repeats; other than its yeast counterpart, PWP2 is most closely homologous to the beta subunits of the trimeric G-protein family and may putatively be involved in signal transduction. Northern blot analysis revealed that the PWP2 gene is expressed in all fetal and adult human tissues examined (3.4 kb mRNA species). This single-copy gene maps approximately 200 kb proximal to PFKL in chromosome 21q22.3 between markers EHOC-1 and D21S25.

Adult↗
PubMed1996

The gene for human U2 snRNP auxiliary factor small 35-kDa subunit (U2AF1) maps to the progressive myoclonus epilepsy (EPM1) critical region on chromosome 21q22.3.

We used targeted exon trapping to clone portions of genes from human chromosome 21q22.3. One trapped sequence showed complete homology with the cDNA of human U2AF35 (M96982; HGM-approved nomenclature U2AF1), which encodes for the small 35-kDa subunit of the U2 snRNP auxiliary factor. Using the U2AF1 cDNA as a probe, we mapped this gene to cosmid Q15D2, a P1, and YAC 350F7 of the Chumakov et al. (Nature 359: 380, 1992) contig, close to the cystathionine-beta-synthase gene (CBS) on 21q22.3. This localization was confirmed by PCR using oligonucleotides from the 3' UTR and by FISH. As U2AF1 associates with a number of different factors during mRNA splicing, overexpression in trisomy 21 individuals could contribute to some Down syndrome phenotypes by interfering with the splicing process. Furthermore, because this gene maps in the critical region for the progressive myoclonus epilepsy I locus (EPM1), mutation analysis will be carried out in patients to evaluate the potential role of U2AF1 as a candidate for EPM1.

Base Sequence↗
PubMed1996

Mapping of the gene for the p60 subunit of the human chromatin assembly factor (CAF1A) to the Down syndrome region of chromosome 21.

Exon trapping was used to clone portions of genes from the Down syndrome critical region (DSCR) of human chromosome 21. One trapped sequence showed complete homology with nucleotide sequence U20980 (GenBank), which corresponds to the gene for the p60 subunit of the human chromatin assembly factor-1 (CAF1A). We mapped this gene to human chromosome 21 by fluorescence in situ hybridization, by the use of somatic cell hybrids, and by hybridization to chromosome 21-specific YACs and cosmids. The CAF1A gene localizes to YACs 745H11 and 230E8 of the Chumakov et al. (1992, Nature 359: 380) YAC contig, within the DSCR on 21q22. This CAF1A, which belongs to the WD-motif family of genes and interacts with other polypeptide subunits to promote assembly of histones to replicating DNA, may contribute in a gene dosage-dependent manner to the phenotype of Down syndrome.

Animals↗
PubMed1996

Cloning, localization and induction of mouse brain glycogen synthase.

The cDNA for mouse brain glycogen synthase has been isolated by screening a mouse cerebral cortical astrocyte lambda ZAP II cDNA library. The mouse brain glycogen synthase cDNA is 3.5 kilobases in length and encodes a protein of 737 amino acids. The coding sequence of mouse brain glycogen synthase cDNA shares approximately 87% nucleotide identity and approximately 96% amino acid identity with the muscle isozyme, while the degree of identity is lower with the liver isozyme. The regional distribution of glycogen synthase mRNA determined by in situ hybridization in the mouse brain reveals a wide distribution throughout the central nervous system with highest densities observed in the cerebellum, hippocampus and olfactory bulb. At the cellular level the expression of brain glycogen synthase mRNA is localized both in astrocytes and neurons with, however, the higher levels observed in astrocytes. Vasoactive intestinal peptide and noradrenaline, two neurotransmitters previously shown to induce a glycogen resynthesis in cultured astrocytes, upregulate the expression of glycogen synthase mRNA in this cell type but not in neurons.

Amino Acid Sequence↗
PubMed1996

Cloning of 559 potential exons of genes of human chromosome 21 by exon trapping.

Chromosome 21 represents approximately 1% of the human genome, and its long arm has been estimated to contain 600-1000 genes. A dense linkage map and almost complete physical maps based on yeast artificial chromosomes (YACs) and cosmids have been developed. We have used exon trapping to identify portions of genes from randomly picked chromosome 21-specific cosmids, to contribute to the creation of the transcription (genic) map of this chromosome and the cloning of its genes. A total of 559 different sequences were identified after elimination of false-positive clones and repetitive elements. Among these, exons for 13 of the 30 known chromosome 21 genes have been "trapped." In addition, a considerable number of trapped sequences showed homologies to genes from other species and to human expressed sequence tags (ESTs). One hundred thirty-three trapped sequences were mapped, and every one mapped back to chromosome 21. We estimate that we have identified portions of up to approximately 40% of all genes on chromosome 21. The genic map of chromosome 21 provides a valuable tool for the elucidation of function of the genes and will enhance our understanding of the pathophysiology of Down syndrome and other disorders of chromosome 21 genes.

Chromosome Mapping↗
PubMed1996

Cloning of the cDNA for a human homologue of the Drosophila white gene and mapping to chromosome 21q22.3.

In an effort to contribute to the transcript map of human chromosome 21 and the understanding of the pathophysiology of trisomy 21, we have used exon trapping to identify fragments of chromosome 21 genes. Two trapped exons, from pools of chromosome 21-specific cosmids, showed homology to the Drosophila white (w) gene. We subsequently cloned the corresponding cDNA for a human homologue of the Drosophila w gene (hW) from human retina and fetal brain cDNA libraries. The gene belongs to the ATP-binding cassette transporter gene family and is homologous to Drosophila w (and to w genes from other species) and to a lesser extent to Drosophila brown (bw) and scarlet (st) genes that are all involved in the transport of eye pigment precursor molecules. A DNA polymorphism with 62% heterozygosity due to variation of a poly (T) region in the 3' UTR of the hW has been identified and used for the incorporation of this gene to the genetic map of chromosome 21. The hW is located at 21q22.3 between DNA markers D21S212 and D21S49 in a P1 clone that also contains marker BCEI. The gene is expressed at various levels in many human tissues. The contributions of this gene to the Down syndrome phenotypes, to human eye color, and to the resulting phenotypes of null or missense mutations are presently unknown.

ATP-Binding Cassette Transporters↗
PubMed1995

Cloning of the cDNA for the human ATP synthase OSCP subunit (ATP5O) by exon trapping and mapping to chromosome 21q22.1-q22.2.

Exon trapping was used to clone portions of potential genes from human chromosome 21. One trapped sequence showed striking homology with the bovine and rat ATP synthase OSCP (oligomycin sensitivity conferring protein) subunit. We subsequently cloned the full-length human ATP synthase OSCP cDNA (GDB/HGMW approved name ATP50) from infant brain and muscle libraries and determined its nucleotide and deduced amino acid sequence (EMBL/GenBank Accession No. X83218). The encoded polypeptide contains 213 amino acids, with more than 80% identity to bovine and murine ATPase OSCP subunits and over 35% identity to Saccharomyces cerevisiae and sweet potato sequences. The human ATP5O gene is located at 21q22.1-q22.2, just proximal to D21S17, in YACs 860G11 and 838C7 of the Chumakov et al. (Nature 359:380, 1992) YAC contig. The gene is expressed in all human tissues examined, most strongly in muscle and heart. This ATP5O subunit is a key structural component of the stalk of the mitochondrial respiratory chain F1F0-ATP synthase and as such may contribute in a gene dosage-dependent manner to the phenotype of Down syndrome (trisomy 21).

Adenosine Triphosphatases↗
PubMed1995

Completion of the La Crosse virus genome sequence and genetic comparisons of the L proteins of the Bunyaviridae.

La Crosse virus is a member of the Bunyavirus genus in the family Bunyaviridae, viruses with trisegmented RNA genomes of mostly negative polarity composed of large (L), medium (M), and small (S) segments. The sequences of the La Crosse/original M and S RNA segments have been previously characterized. Using reverse transcriptase in conjunction with PCR amplification, we have obtained the nucleotide sequence of the L RNA segment, which encodes the viral polymerase in a single large open reading frame. Comparison of the amino acid sequence of the LAC L protein with the sequence of other polymerases from members of the Bunyaviridae, demonstrated the presence of several conserved motifs, some of which are characteristic of many polymerase proteins. A genetic tree comparing the available polymerase proteins of the Bunyaviridae provides insights into the phylogenetic relationships within this large family. Members of the genus Bunyavirus, which are mosquito-borne and infect mammals, have a closer relationship to the plant viruses represented by tomato spotted wilt virus (Tospovirus genus) than to viruses of other genera in the family Bunyaviridae.

Amino Acid Sequence↗
PubMed1995

Localization of 102 exons to a 2.5 Mb region involved in Down syndrome.

Exon amplification has been applied to a 2.5 Mb region of chromosome 21 that has been associated with some features of Down syndrome (DS). Identification of the majority of genes from this region will facilitate the correlation of the over-expression of particular genes with specific phenotypes of DS. Over 100 gene fragments have been isolated from this 2.5 Mb segment. The exons have been characterized by sequence analysis, comparison with public databases and expansion to cDNA clones. Localization of the exons to chromosome 21 has been determined by hybridization to genomic Southern blots and to YAC and cosmid clones representing the region. This has resulted in a higher resolution physical map with a marker approximately every 25 kb. This integrated physical and transcript map will be valuable for fine mapping of DNA from individuals with partial aneuploidy of chromosome 21 as well as for assessing and ultimately generating a complete gene map of this segment of the genome.

Base Sequence↗
PubMed1992

VIP receptor subtypes in mouse cerebral cortex: evidence for a differential localization in astrocytes, microvessels and synaptosomal membranes.

The binding characteristics of a monoiodinated form of vasoactive intestinal peptide (M-[125I]VIP) to the membranes of astrocytes, intraparenchymal microvessels and synaptosomes were analyzed in mouse cerebral cortex. Binding to astrocytes, studied in primary cultures, indicates the presence of a single class of high affinity binding sites with a Kd of 3.3 nM and a Bmax of 565 fmol/mg protein. The structurally related peptide secretin does not compete for sites labeled by M-[125I]VIP. In cultured astrocytes, VIP has been previously shown to promote glycogenolysis. Secretin, despite its lack of interaction with sites labeled by M-[125I]VIP, stimulates glycogenolysis with an EC50 of 0.5 nM, thus demonstrating the presence in astrocytes of functional secretin receptors independent from those for VIP. Trypsinization of the primary astrocyte cultures followed by replating as secondary cultures, reveals a second class of low affinity binding sites, with a Kd of 41.3 nM and a Bmax of 881 fmol/mg protein. Secretin does not compete for this class of low affinity binding sites either. Binding of M-[125I]VIP to intraparenchymal microvessels reveals the presence of two classes of binding sites with Kd of 1.4 and 30.3 nM, and Bmax of 7.1 and 73.8 pmol/mg protein, respectively. Similar to what is observed in primary or secondary astrocyte cultures, secretin does not interact with these sites. In this cell type VIP stimulates cAMP formation with an EC50 of 18 nM, while secretin is ineffective. Finally, in agreement with previous reports in rat and guinea pig cerebral cortex, two classes of binding sites are observed in synaptosomal membranes: a high affinity class with a Kd of 4.9 nM and a Bmax of 316 fmol/mg protein, and a low affinity class with a Kd of 42.8 nM and a Bmax of 1578 fmol/mg protein. In contrast to what is observed in non-neuronal membranes, in synaptosomal membranes, secretin effectively competes for sites labeled by M-[125I]VIP with an EC50 of approximately 150 nM. These results indicate that secretin may represent a useful tool to discriminate between neuronal and non-neuronal VIP binding sites, since it competes with M-[125I]VIP exclusively for the neuronal class of binding sites.

Animals↗
PubMed1989

Secretion of an Mr 60000 protein by benomyl-treated cells of Neurospora crassa.

In the presence of the microtubule inhibitor benomyl at micron concentrations, cells of Neurospora crassa wild type strain St. Lawrence 74A were found to secrete high amounts of an Mr 60 000 protein into the culture medium (about 35 micrograms/ml after a 12 h treatment). The secretion also occurred after treatment with the other antitubulin drugs carbendazim (MBC), nocodazole, thiabendazole, and griseofulvin. This secretion is apparently induced by the specific action of benomyl on N. crassa beta-tubulin as no secretion of the Mr 60 000 protein could be detected after treatment of the benomyl-resistant mutant bml 511 (r), mutated in its beta-tubulin gene (Orbach et al., Mol. Cell. Biol. 6, 2452-2461 (1986)). The secretion was abolished by 12 microM cycloheximide, a protein synthesis inhibitor. The Mr 60 000 protein could be separated into two main and four secondary components by two-dimensional gel electrophoresis (pI 6.67 and 6.52 and pI 6.93, 6.81, 6.44, and 6.32, respectively). The Mr 60 000 protein was not a major intracellular protein of benomyl-treated cells and could only be revealed by immunoblotting with polyclonal antibodies raised against the extracellular form. It was undetectable in untreated cells collected at various stages of vegetative growth or in their culture medium.

Benomyl↗
PubMed1988

LaCrosse virus gene expression in mammalian and mosquito cells.

LaCrosse virus infection of mammalian BHK cells is highly cytopathic, whereas that of mosquito C6/36 cells is asymptomatic and persistent. When the individual mRNAs and their genome segments are followed in parallel infections, cytopathic effects were found to correlate with the rate of synthesis, but not the accumulation, of the viral RNAs. The change from the acute to the persistent phase of the infection in C6/36 cells was found to take place at 24 hr p.i., at which time genome and N protein synthesis was severely reduced, even though mRNA levels remained high. When the persistent infection was followed for 72 days, the total amounts of genomes and their relative proportions were found to fluctuate greatly, whereas mRNA levels were either severely reduced or undetectable. DI genomes could not be detected during this time. The self-limiting nature of the mosquito cell infection appears to be due the translational control of N protein synthesis.

Animals↗
PubMed1988

Induction of multiple germ tubes in Neurospora crassa by antitubulin agents.

The antitubulin fungicide benomyl suppressed the linear growth of Neurospora crassa wild type strain St. Lawrence 74 at micromolar concentrations. The rate of germination of macroconidia was not affected. Macroconidia exposed to 1.7 microM benomyl for 5 h formed multiple germ tubes. When germlings incubated for 4 h were exposed to 1.7 microM benomyl for 3 h, their germ tube stopped growing, swelled and emitted several branches. Normal linear growth was restored after removal of the fungicide. Linear growth of N. crassa was resistant up to 16 microM nocodazole. This drug induced multipolar germination at 8 microM, and griseofulvin only at 140 microM. The microtubule (MT) cytoskeleton of N. crassa could be revealed by indirect immunofluorescence with the monoclonal antibody YOL 1/34 directed against yeast alpha-tubulin. We detected no striking effects of the benomyl treatments on MT organization. The MT-stabilizing agents deuterium oxide (D2O) and cAMP have no antagonistic effects on the benomyl-induced multipolar germination. The positioning of nuclei and mitochondria was determined from the DAPI and Rhodamine 123 fluorescence patterns, respectively. Benomyl inhibited nuclear migration into multiple germ tubes. Quantitative scanning cytophotometry revealed a peak in the intensity of the mitochondria-associated Rhodamine 123 fluorescence near the apex of untreated germlings. This peak disappeared in multiple germ tubes. Benomyl-resistant mutant bml 511 (r), mutated in its beta-tubulin gene, germinated normally in the presence of the fungicide. This strongly suggests that multiple germ tube formation was due to the effect of benomyl on beta-tubulin. Benomyl-resistant strain 74-3, constructed by reintroducing the cloned mutant N. crassa beta-tubulin gene into the cells by transformation, displayed a partial resistance to benomyl with respect to multipolar germination. Its rate of germination was slow (50% germination reached after 4 h at 37 degrees C as compared to 2.5 h for the wild type). In contrast to N. crassa, the other ascomycete Aspergillus nidulans is nocodazole-sensitive (linear growth suppressed at 1.6 microM). It did not respond to the MT inhibitors benomyl and nocodazole with respect to the pattern of germ tube emergence. Our results suggest that microtubule or membrane beta-tubulin is involved in the maintenance of developmental polarity during germ tube emergence and growth of N. crassa.

Benomyl↗
PubMed1986

La Crosse virus small genome mRNA is made in the cytoplasm.

The cellular site of La Crosse virus S genome mRNA synthesis was examined by pulse-labeling infected cells for various times and determining the amount of labeled S mRNA in both the cytoplasmic and nuclear fractions. With pulse times as short as 3 min, La Crosse virus S genome transcription was found to be localized in the cytoplasm.

Animals↗