Cells deficient in PARP-1 show an accelerated accumulation of DNA single strand breaks, but not AP sites, over the PARP-1-proficient cells exposed to MMS.

Pachkowski, B; Tano, K; Afonin, V; Elder, RH; Takeda, S; Watanabe, M; Swenberg, J; Nakamura, J

Abstract

Poly(ADP-ribose) polymerase-1 (PARP-1) is a base excision repair (BER) protein that binds to DNA single strand breaks (SSBs) and subsequently synthesizes and transfers poly(ADP-ribose) polymers to various nuclear proteins. Numerous biochemical studies have implicated PARP-1 as a modulator of BER; however, the role of PARP-1 in BER in living cells remains unclear partly due to lack of accurate quantitation of BER intermediates existing in cells. Since DT40 cells, chicken B lymphocytes, naturally lack PARP-2, DT40 cells allow for the investigation of the PARP-1 null phenotype without confounding by PARP-2. To test the hypothesis that PARP-1 is necessary for efficient BER during methylmethane sulfonate (MMS) exposure in vertebrate cells, intact DT40 cells and their isogenic PARP-1 null counterparts were challenged with different exposure scenarios for phenotypic characterization. With chronic exposure, PARP-1 null cells exhibited sensitivity to MMS but with an acute exposure did not accumulate base lesions or AP sites to a greater extent than wild-type cells. However, an increase in SSB content in PARP-1 null cell DNA, as indicated by glyoxal gel electrophoresis under neutral conditions, suggested the presence of BER intermediates. These data suggest that during exposure, PARP-1 impacts the stage of BER after excision of the deoxyribosephosphate moiety from the 5' end of DNA strand breaks by polymerase beta.

Citation

Pachkowski, B., Tano, K., Afonin, V., Elder, R., Takeda, S., Watanabe, M., …Nakamura, J. (2009). Cells deficient in PARP-1 show an accelerated accumulation of DNA single strand breaks, but not AP sites, over the PARP-1-proficient cells exposed to MMS. Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis, 671(1-2), 93-9. https://doi.org/10.1016/j.mrfmmm.2009.09.006

• Journal Article Type: Article
• Publication Date: Dec 1, 2009
• Deposit Date: Oct 6, 2011
• Journal: Mutation research -Fundamental and Molecular Mechanisms of Mutagenesis
• Print ISSN: 0027-5107
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 671
• Issue: 1-2
• Pages: 93-9
• DOI: https://doi.org/10.1016/j.mrfmmm.2009.09.006
• Keywords: Alkylating agent, N7-methylguanine, AP sites, base excision repair, single strand breaks, PARP-1
• Publisher URL: http://dx.doi.org/ 10.1016/j.mrfmmm.2009.09.006