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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 and 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) , pp. 93-9.

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    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.

    Item Type: Article
    Uncontrolled Keywords: Alkylating agent, N7-methylguanine, AP sites, base excision repair, single strand breaks, PARP-1
    Themes: Health and Wellbeing
    Schools: Colleges and Schools > College of Science & Technology > School of Environment and Life Sciences > Biomedical Research Centre
    Journal or Publication Title: Mutation research -Fundamental and Molecular Mechanisms of Mutagenesis
    Publisher: Elsevier
    Refereed: Yes
    ISSN: 0027-5107
    Depositing User: RH Elder
    Date Deposited: 06 Oct 2011 16:28
    Last Modified: 20 Aug 2013 18:12
    URI: http://usir.salford.ac.uk/id/eprint/17995

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