Effect of ultraviolet light, methyl methanesulfonate and ionizing radiation on the genotoxic response and apoptosis of mouse fibroblasts lacking c-Fos, p53 or both

Author： Lackinger D. Eichhorn U. Kaina B.

Publisher： Oxford University Press

ISSN： 1464-3804

Source： Mutagenesis, Vol.16, Iss.3, 2001-05, pp. : 233-241

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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.