The role of Sirt1 in renal rejuvenation and resistance to stress.

This issue of the JCI includes studies demonstrating that sirtuin 1 (Sirt1), a NAD+-dependent deacetylase, slows renal senescence and safeguards cells in the renal medulla. Kume et al. demonstrated that caloric restriction protected the aging kidney by preserving renal Sirt1 expression, the latter deacetylating forkhead box O3a (FOXO3a), inducing Bnip 3, and promoting mitochondrial autophagy. Sirt1 expression, as shown by He et al., enabled interstitial cells to withstand the oxidizing medullary environment and exerted antiapoptotic and antifibrotic effects in the obstructed kidney. Sirt1 is thus an important participant in renal cytoprotective responses to aging and stress.