Impaired SIRT1 nucleocytoplasmic shuttling in the senescent heart during ischemic stress

A “longevity” gene, sirtuin 1 (SIRT1), can attenuate age‐dependent induction of left ventricular dysfunction. This study aimed to characterize the role of SIRT1 in the tolerance of aged heart to ischemic insults. Male C57BL/6 young (4–6 mo) and aged (24–26 mo) mice were used to determine the role of SIRT1 in myocardial ischemia/reperfusion (I/R) tolerance. SIRT1 localization was assessed by confocal microscopy. Immunoblotting was used to evaluate SIRT1 expression and translocation. The results demonstrated that SIRT1 is expressed predominantly as a sumoylated form in cardiomyocyte nuclei. Moreover, cardiac overexpression of desumoylase, sentrin‐specific protease 2 (SENP2), significantly reduces nuclear sumoylated SIRT1 levels (P