Muscle or liver-specific Sirt3 deficiency induces hyperacetylation of mitochondrial proteins without affecting global metabolic homeostasis.

Sirt3 is a mitochondrial sirtuin, predominantly expressed in highly metabolic tissues. Germline ablation of Sirt3 has major metabolic consequences, including increased susceptibility to metabolic damage and oxidative stress after high fat feeding. In order to determine the contribution of liver and skeletal muscle to these phenotypes, we generated muscle-specific Sirt3 (Sirt3(skm-/-)) and liver-specific Sirt3 (Sirt3(hep-/-)) knock-out mice. Despite a marked global hyperacetylation of mitochondrial proteins, Sirt3(skm-/-) and Sirt3(hep-/-) mice did not manifest any overt metabolic phenotype under either chow or high fat diet conditions. Similarly, there was no evidence for increased oxidative stress in muscle or liver when Sirt3 was ablated in a tissue-specific manner. These observations suggest that the mitochondrial hyperacetylation induced by Sirt3-deletion in a tissue specific manner is not necessarily linked to mitochondrial dysfunction and does not recapitulate the metabolic abnormalities observed in the germline Sirt3 knock-out mice.