Nucleic Acids Research Advance Access originally published online on August 5, 2008
Nucleic Acids Research 2008 36(15):5111-5121; doi:10.1093/nar/gkn480
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Nucleic Acids Research, 2008, Vol. 36, No. 15 5111-5121
Published by Oxford University Press, 2008
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
XRCC1 protects against the lethality of induced oxidative DNA damage in nondividing neural cells
1Laboratory of Molecular Gerontology and 2Laboratory of Neurosciences, Biomedical Research Center, National Institute of Aging (NIA)/National Institutes of Health (NIH), 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224, USA
*To whom correspondence should be addressed. Tel: +1 410 558 8153; Fax: +1 410 558 8157; Email: wilsonda{at}mail.nih.gov
Received March 21, 2008. Revised June 11, 2008. Accepted July 9, 2008.
XRCC1 is a critical scaffold protein that orchestrates efficient single-strand break repair (SSBR). Recent data has found an association of XRCC1 with proteins causally linked to human spinocerebellar ataxias—aprataxin and tyrosyl-DNA phosphodiesterase 1—implicating SSBR in protection against neuronal cell loss and neurodegenerative disease. We demonstrate herein that shRNA lentiviral-mediated XRCC1 knockdown in human SH-SY5Y neuroblastoma cells results in a largely selective increase in sensitivity of the nondividing (i.e. terminally differentiated) cell population to the redox-cycling agents, menadione and paraquat; this reduced survival was accompanied by an accumulation of DNA strand breaks. Using hypoxanthine–xanthine oxidase as the oxidizing method, XRCC1 deficiency affected both dividing and nondividing SH-SY5Y cells, with a greater effect on survival seen in the former case, suggesting that the spectrum of oxidative DNA damage created dictates the specific contribution of XRCC1 to cellular resistance. Primary XRCC1 heterozygous mouse cerebellar granule cells exhibit increased strand break accumulation and reduced survival due to increased apoptosis following menadione treatment. Moreover, knockdown of XRCC1 in primary human fetal brain neurons leads to enhanced sensitivity to menadione, as indicated by increased levels of DNA strand breaks relative to control cells. The cumulative results implicate XRCC1, and more broadly SSBR, in the protection of nondividing neuronal cells from the genotoxic consequences of oxidative stress.