Lack of altered frequency of sister-chromatid exchanges in poly(ADP-ribose) glycohydrolase-deficient mouse ES cells treated with methylmethanesulfonate

Poly(ADP-ribose) glycohydrolase plays a central role in poly(ADP-ribose) degradation, cleaving α(ribose-ribose) bonds to produce ADP-ribose. We previously generated Parg-deficient (Parg+/- and Parg-/-) mouse embryonic stem (ES) cells by disrupting exon 1 of the Parg gene, and showed the Parg-/- ES cells to be hypersensitive to methylmethanesulfonate, an alkylating agent. To clarify the role of Parg in the maintenance of genomic stability, we examined the frequency of sister-chromatid exchanges (SCEs) in Parg+/+ and Parg-/- ES cells with and without methylmethanesulfonate treatment. No difference was observed in the spontaneous frequency of SCEs between the Parg genotypes, treatment with methyl-methanesulfonate at 50 μM causing approximately 2-fold elevation in both cases.(Contributed by Takashi SUGIMURA, M. J. A., Dec. 12, 2003)