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C A Vaslet

Publications and source records attributed to C A Vaslet.

13 recordsLinked to original sources
PubMed2000

Identification of candidate growth-regulating genes that are overexpressed in late gestation fetal liver in the rat.

We have shown previously that hepatocyte proliferation in the late gestation fetal rat is mediated by growth factor-independent mechanisms that are distinct from the signaling pathways that promote proliferation of adult rat hepatocytes. In the present studies, we identified six candidate growth-regulating genes that are overexpressed in fetal rat liver (embryonic day 19, 2 days pre-term) relative to adult rat liver using suppressive subtractive hybridization. These included the following: Grb10, a growth factor receptor binding protein; eps15, a growth factor receptor substrate; nuc2+, a retinoblastoma protein binding protein; cdc25B, a cell cycle tyrosine phosphatase; the peroxisome proliferator-activated receptor PPAR alpha; and a deoxyuridine triphosphatase that functions as a PPAR alpha binding partner. In every case, the ontogeny of the expression of these genes declined postnatally in a manner consistent with the transition from a fetal to an adult hepatocyte phenotype. None were found to be cell cycle-dependent, in that they did not show expression that followed perinatal changes in hepatocyte cell cycle activity. Based on our identification of these genes and previous work characterizing their role in growth regulation, we conclude that they may contribute to the mitogenic signaling phenotype of fetal rat hepatocytes.

Animals↗
PubMed1997

Susceptibility of p53-deficient mice to induction of mesothelioma by crocidolite asbestos fibers.

Exposure of mesothelial cells to asbestos fibers in vitro has been shown to induce DNA damage mediated by oxidants. An early cellular response to DNA damage is increased expression of the p53 protein. This protein induces transcription of genes that activate cell cycle checkpoints or induce apoptosis. A murine mesothelial cell line that spontaneously acquired a point mutation in the p53 gene shows increased sensitivity to DNA damage induced by crocidolite asbestos fibers. It is hypothesized that p53-deficient mice will show increased sensitivity to the genotoxic effects of asbestos and accelerated development of malignant mesotheliomas.

Alleles↗
PubMed1996

Spontaneous p53 mutation in murine mesothelial cells: increased sensitivity to DNA damage induced by asbestos and ionizing radiation.

The p53 gene regulates the G1 cell cycle checkpoint in response to DNA damage. A primary murine mesothelial cell line (D9) spontaneously acquired a point mutation at codon 135 in exon 5 of the p53 gene, resulting in substitution of alanine for proline; early passage D9 cells expressed wild-type p53. The growth rate of late passage D9 cells that acquired the p53 mutation was increased compared to that of early passage cells; however, this mutation was not sufficient to confer tumorigenicity to this cell line. Mammalian cells that express wild-type p53 show a transient arrest in G1 after exposure to ionizing radiation. Early passage D9 cells showed a G1 arrest following ionizing radiation, while late passage D9 cells arrested in G2 or mitosis. The clastogenic effects of ionizing radiation can be demonstrated by the cytokinesis-arrested micronucleus assay. Following treatment with cytochalasin B to arrest cytokinesis, ionizing radiation induced micronuclei in 50% of late passage D9 cells compared to 15% of early passage cells. After exposure to 15 micrograms/cm2 of crocidolite asbestos fibers, 18% of late passage cells had micronuclei compared to 4% of early passage cells. It is hypothesized that loss of the G1 cell cycle checkpoint contributes to genetic instability in murine mesothelial cells.

Animals↗
PubMed1995

Molecular cloning of the human gene SUVCC3 associated with the formation of DNA-protein crosslinks following exposure to solar UV radiation.

DRP 153 cells, which are hypersensitive to solar UV and deficient in the formation of DNA-protein crosslinks (DPC) following irradiation, were transfected with human DNA and a secondary transformant obtained in which a normal DPC response and solar UV sensitivity reestablished. DNA from this secondary transformant was used to construct a genomic DNA library from which a recombinant phage was isolated containing the human gene capable of restoring a normal DPC response and solar UV sensitivity to DRP 153. This gene has been designated SUVCC3 to denote solar UV cross-complementing gene number 3.

Adult↗
PubMed1995

Molecular cloning of the human gene SUVCC2 associated with mutagenesis following the induction of non-dimer DNA damages by solar UV radiation.

A mutant cell line, DRP 512, sensitive to the induction of non-dimer DNA damages produced by solar UV radiation was derived from ICR 2A frog cells. In addition, the DRP 512 cells exhibited an abnormally high level of ouabain-resistant mutants after exposure to solar UV. A level of 1.1. mutants per 10(6) survivors per kJ m-2 was measured for ICR 2A whereas the yield was 4.2 mutants per 10(6) survivors per kJ m-2 for the solar-UV-sensitive cell line. The DRP 512 cells were transfected with human DNA and a secondary transformant obtained in which normal solar UV sensitivity and mutation induction were restored. DNA from this secondary transformant was used to construct a genomic DNA library from which a recombinant phage was isolated containing the human gene capable of restoring normal solar UV sensitivity and mutation induction to DRP 512. This gene has been designated SUVCC2.

Adult↗
PubMed1995

Molecular cloning of the human gene SUVCC1 associated with the repair of nondimer DNA damage induced by solar UV radiation.

A mutant cell line, DRP 287, sensitive to solar UV radiation and deficient in the repair of solar UV-induced nondimer DNA damage, was derived from ICR 2A frog cells. These cells were transfected with human DNA and a secondary transformant obtained in which normal solar UV sensitivity was restored and the repair defect corrected. The DNA from this secondary transformant was used to construct a genomic DNA library from which a recombinant phage was isolated containing the human gene capable of restoring normal solar UV sensitivity and correcting the repair defect in the DRP 287 cells. This represents the first human gene which has been isolated that is specifically involved in the repair of nondimer DNA damage induced by solar UV radiation. It has been designated SUVCC1 to denote solar UV cross-complementing gene number 1.

Animals↗
PubMed1994

Functional expression and site-directed mutagenesis of a synthetic gene for alpha-bungarotoxin.

In order to explore the structure-function relationships of the curare mimetic alpha-neurotoxins we have constructed and cloned a synthetic gene for Bungarus multicinctus alpha-bungarotoxin which is expressed in Escherichia coli. The recombinant alpha-bungarotoxin is expressed as a fusion protein with alpha-bungarotoxin linked to the COOH-terminal end of the T7 Gene 9-encoded coat protein. After treatment of the fusion protein with Factor Xa protease, a recombinant alpha-bungarotoxin is released that co-migrates with authentic alpha-bungarotoxin upon reverse-phase high performance liquid chromatography and ion-exchange chromatography. Final yields of active recombinant alpha-bungarotoxin were about 0.4 mg/liter of starting bacterial culture. The recombinant alpha-bungarotoxin contains 10 additional residues linked to the NH2-terminal Ile of the alpha-bungarotoxin sequence due apparently to the inaccessibility of the engineered cleavage site to Factor Xa. Nevertheless, the recombinant alpha-bungarotoxin is capable of binding to the nicotinic acetylcholine receptor with an apparent affinity that is only decreased approximately 1.7-fold from that of authentic alpha-bungarotoxin. Alanine substitution of a residue, Asp30, highly conserved among alpha-neurotoxins and previously suggested to play a key role in receptor recognition, resulted in a recombinant alpha-bungarotoxin whose receptor binding activity is indistinguishable from authentic alpha-bungarotoxin.

Alanine↗
PubMed1994

Oxygen radicals and asbestos carcinogenesis.

Asbestos fibers have been shown to generate reactive oxygen species using a variety of in vitro assays. It is hypothesized that these highly reactive metabolites mediate the development of malignant mesothelioma induced by asbestos fibers. DNA is a potential target of oxidant attack. Adaptive responses to oxidant injury have been described during exposure of mesothelial cells to asbestos fibers in vitro. Failure of these adaptive responses may lead to genetic instability and alterations in oncogenes and tumor suppressor genes that confer a proliferative advantage to emerging neoplastic mesothelial cells.

Animals↗
PubMed1980

Isolation and mapping of a cloned ribosomal protein gene of Drosophila melanogaster.

Molecular cloning techniques are particularly well suited to the study of gene organization in Drasophila melanogaster because recombinant DNA can easily be localized in the genome by in situ hybridization to salivary gland polytene chromosomes. We report here the isolation and preliminary characterization of a recombinant phage, designated C25, containing a bona fide D. melanogaster ribosomal protein gene. In situ hybridization demonstrates that this sequence maps to region 99D on chromosome 3.

Animals↗
PubMedDate not supplied

Growth factor responses and protooncogene expression of murine mesothelial cell lines derived from asbestos-induced mesotheliomas.

Repeated intraperitoneal injections of crocidolite asbestos fibers induced diffuse malignant mesotheliomas in mice. A series of mesothelial cell lines was isolated from mice at different stages in the development of these tumors. The cell lines isolated from mice with mesotheliomas recapitulated their growth pattern in vivo and were tumorigenic when reinjected into syngeneic mice. Similar to human mesothelial cells, growth of the murine cell lines was stimulated by epidermal growth factor. Reactive mesothelial cells and mesotheliomas expressed the receptor for this growth factor. Crocidolite asbestos fibers have been reported to induce sustained expression of the c-fos and c-jun protooncogenes in rat pleural mesothelial cells in vitro (Heintz et al, Proc. Natl. Acad. Sci. USA 90: 3299-303, 1993). Human malignant mesotheliomas have been shown to express c-fos in situ (Ramael et al, Histol. Histopathol. 10: 639-643, 1995). Two of the cell lines derived from highly invasive murine mesotheliomas overexpressed c-fos and c-jun. This murine model recapitulates the histopathology, growth factor responses, and protooncogene expression of human malignant mesotheliomas.

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