Abstract
Werner syndrome is an autosomal recessive disorder associated with premature aging and cancer predisposition caused by mutations of the WRN gene. WRN is a member of the RecQ DNA helicase family with functions in maintaining genome stability. Sir2, an NAD-dependent histone deacetylase, has been proven to extend life span in yeast and Caenorhabditis elegans. Mammalian Sir2 (SIRT1) has also been found to regulate premature cellular senescence induced by the tumor suppressors PML and p53. SIRT1 plays an important role in cell survival promoted by calorie restriction. Here we show that SIRT1 interacts with WRN both in vitro and in vivo; this interaction is enhanced after DNA damage. WRN can be acetylated by acetyltransferase CBP/p300, and SIRT1 can deacetylate WRN both in vitro and in vivo. WRN acetylation decreases its helicase and exonuclease activities, and SIRT1 can reverse this effect. WRN acetylation alters its nuclear distribution. Down-regulation of SIRT1 reduces WRN translocation from nucleoplasm to nucleoli after DNA damage. These results suggest that SIRT1 regulates WRN-mediated cellular responses to DNA damage through deacetylation of WRN.
Highlights
Werner syndrome (WS)3 is a human autosomal recessive disorder that displays symptoms of premature aging, including graying and loss of hair, wrinkling and ulceration of skin, atherosclerosis, osteoporosis, and cataracts
We provide evidence that SIRT1 can interact with WRN both in vitro and in vivo, and this interaction is enhanced after DNA damage
Endogenous SIRT1 can clearly be co-immunoprecipitated with WRN (Fig. 1c, lane 5 versus lane 8). This interaction was increased in the cells after a 6-h treatment with etoposide or H2O2 (Fig. 1c, lanes 5–7), suggesting that the possible regulation of WRN by SIRT1 is enhanced after DNA damage
Summary
Werner syndrome (WS)3 is a human autosomal recessive disorder that displays symptoms of premature aging, including graying and loss of hair, wrinkling and ulceration of skin, atherosclerosis, osteoporosis, and cataracts. These results suggest that SIRT1 regulates WRN-mediated cellular responses to DNA damage through deacetylation of WRN. Regulating WRN by SIRT1 different DNA-damaging treatments found that acetylation of endogenous WRN is involved in its reversible translocation from nucleoli to nucleoplasm [19].
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