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Research Paper|Volume 1, Issue 1|pp 109—121

SIRT6 stabilizes DNA-dependent Protein Kinase at chromatin for DNA double-strand break repair

Ronald A. McCord1,2,6, Eriko Michishita1,2,6, Tao Hong1,2,6, Elisabeth Berber1,2,6, Lisa D. Boxer1,2, Rika Kusumoto3, Shenheng Guan4, Xiaobing Shi5, Or Gozani5, Alma L. Burlingame4, Vilhelm A. Bohr3, Katrin F. Chua1,2
  • 1Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
  • 2Geriatric Research, Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA 94304, USA
  • 3Department of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
  • 4Department of Pharmaceutical Chemistry and Mass Spectrometry Facility, University of California, San Francisco, CA 94143, USA
  • 5Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
  • 6These authors contributed independently to this work
Received: December 28, 2008Accepted: January 13, 2009Published: January 15, 2009
https://doi.org/10.18632/aging.100011

Copyright: © 2009 McCord et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

The Sir2 chromatin regulatory factor links maintenance of genomic stability to life span extension in yeast. The mammalian Sir2 family member SIRT6 has been proposed to have analogous functions, because SIRT6-deficiency leads to shortened life span and an aging-like degenerative phenotype in mice, and SIRT6 knockout cells exhibit genomic instability and DNA damage hypersensitivity. However, the molecular mechanisms underlying these defects are not fully understood. Here, we show that SIRT6 forms a macromolecular complex with the DNA double-strand break (DSB) repair factor DNA-PK (DNA-dependent protein kinase) and promotes DNA DSB repair. In response to DSBs, SIRT6 associates dynamically with chromatin and is necessary for an acute decrease in global cellular acetylation levels on histone H3 Lysine 9. Moreover, SIRT6 is required for mobilization of the DNA-PK catalytic subunit (DNA-PKcs) to chromatin in response to DNA damage and stabilizes DNA-PKcs at chromatin adjacent to an induced site-specific DSB. Abrogation of these SIRT6 activities leads to impaired resolution of DSBs. Together, these findings elucidate a mechanism whereby regulation of dynamic interaction of a DNA repair factor with chromatin impacts on the efficiency of repair, and establish a link between chromatin regulation, DNA repair, and a mammalian Sir2 factor.