SIRT1 and atherosclerosis: In addition, the levels of SIRT1 and SIRT6, protein deacetylases that play key roles in regulating DNA damage repair, maintaining telomere length and metabolic homeostasis,250 are decreased in atherosclerosis.251 SIRT6 deficiency promotes endothelial cell senescence, leading to impaired vasodilation, vascular dysfunction and atherosclerosis.