SIRT5 deacylates metabolism-related proteins and attenuates hepatic steatosis in ob/ob mice

Background: Sirtuin 5 (SIRT5) is a NAD(+)-dependent lysine deacylase. The SIRT5 deficiency mouse model shows that it is dispensable for metabolic homeostasis under normal conditions. However, the biological role of SIRT5 and acylation in pathological states such as obesity and type 2 diabetes (T2D) remains elusive. Methods: The hepatic SIRT5-overexpressing ob/ob mouse model (ob/ob-SIRT5 OE) was established by CRISPR/Cas9 gene editing tool Protein malonylation and succinylation lysine sites were identified by immunoprecipitation coupled lipid chromatography - tandem mass spectrometry (LC-MS/MS) methods. Findings: The ob/ob-SIRT5 OE mice showed decreased malonylation and succinylation, improved cellular glycolysis, suppressed gluconeogenesis, enhanced fatty acid oxidation, and attenuated hepatic steatosis. A total of 955 malonylation sites on 434 proteins and 1377 succinylation sites on 429 proteins were identified and quantitated. Bioinformatics analysis revealed that malonylation was the major SIRT5 target in the glycolysis/gluconeogenesis pathway, whereas succinylation was the preferred SIRT5 target in the oxidative phosphorylation pathway. Interpretation: Hepatic overexpression of SIRT5 ameliorated the metabolic abnormalities of ob/ob mice, probably through demalonylating and desuccinylating proteins in the main metabolic pathways. SIRT5 and related acylation might be potential targets for metabolic disorders. (C) 2018 The Authors. Published by Elsevier B.V.