title: Effect of ultraviolet light, methyl methanesulfonate and ionizing radiation on the genotoxic response and apoptosis of mouse fibroblasts lacking c-Fos, p53 or both.
abstract: c-Fos and p53 are DNA damage-inducible proteins that are involved in gene regulation, cell cycle checkpoint control and cell proliferation following exposure to genotoxic agents. To investigate comparatively the role of c-Fos and p53 in the maintenance of genomic stability and the induction of apoptosis, we generated mouse fibroblast cell lines from knockout mice deficient for either c-fos (fos -/-) or p53 (p53-/-) or for both gene products (fosp53-/-). The sensitivity of these established cell lines was compared with the corresponding wild-type cells as to the cytotoxic, clastogenic and apoptosis-inducing effects of ultraviolet (UV-C) light and methyl methanesulfonate (MMS). Additionally, we analysed the frequency of apoptosis of the cell lines after treatment with ionizing radiation (IR). We observed c-fos-/-, p53-/- and fosp53-/- cells to be more sensitive than wild-type cells with respect to cell death, as measured in a cytotoxicity (MTT) assay. Regarding apoptosis, all deficient cell lines displayed hypersensitivity to UV-C light, MMS and IR. With chromosomal aberrations as the endpoint, the sensitivity of the double-knockout cells was between wild-type and single-knockouts. The results indicate that both c-Fos and p53 play an important role in protecting fibroblasts against a broad range of genotoxic agents. The results also show that, in fibroblasts, apoptosis induced by UV-C light, MMS and IR does not require p53 and that, in this cell type, p53 rather protects against DNA damage-induced apoptotic cell death.
authors.affiliation: Institute of Toxicology, Division of Applied Toxicology, University of Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Lackinger
authors.forename: U
authors.initials: U
authors.lastname: Eichhorn
authors.forename: B
authors.initials: B
authors.lastname: Kaina
mesh_terms: D000818:Animals; D017209:Apoptosis; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D008741:Methyl Methanesulfonate / Q000633:toxicity*; D051379:Mice; D018345:Mice, Knockout; D009153:Mutagens; D009336:Necrosis; D016133:Polymerase Chain Reaction; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D011839:Radiation, Ionizing; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D016760:Proto-Oncogene Proteins c-fos; D016159:Tumor Suppressor Protein p53; D008741:Methyl Methanesulfonate