SIRT5: a safeguard against oxidative stress-induced apoptosis in cardiomyocytes.

ABSTRACT

BACKGROUND: SIRT5 is located in the mitochondria, and plays a crucial role in the regulation of metabolic process and cellular apoptosis. Cardiomyocytes are abundant in mitochondria. However, the role of SIRT5 in oxidative stress-induced apoptosis is still unknown in cardiomyocytes. METHODS AND RESULTS: Western blots analysis revealed that SIRT5 is significantly down-regulated in cardiomyocytes upon oxidative stress. MTT assay, DAPI staining, and caspase 3/7 activity assay were used to estimate apoptosis development. The result suggested that compared with the wild-type group, SIRT5 knockdown results in a marked reduction in cell viability, and a significant increase in the number of apoptotic cells and the caspase 3/7 activity. Protein immunoprecipitation revealed a direct interaction between Bcl-Xl and SIRT5. Apoptosis assay and western blot anaylsis suggested that SIRT5 levels could affect the levels of Bcl-Xl expression, but have no effect on the apoptosis development in Bcl-Xl knockdown cells. CONCLUSION: This study reveals a novel role of SIRT5 in the regulation of oxidative stress-induced apoptosis in cardiomyocytes. Pharmacological interventions on SIRT5 expression may be useful in the treatment of oxidative stress-related cardiac injury.