Loss of sirtuin 4 leads to elevated glucose- and leucine-stimulated insulin levels and accelerated age-induced insulin resistance in multiple murine genetic backgrounds

• Published in: Journal of inherited metabolic disease Vol. 41; no. 1; pp. 59 - 72
• Main Authors: Huynh, Frank K., Hu, Xiaoke, Lin, Zhihong, Johnson, James D., Hirschey, Matthew D.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.01.2018; Blackwell Publishing Ltd
• Subjects: Acetylation; Age; Age Factors; Animals; Biochemistry; Biomarkers - blood; Blood Glucose - metabolism; Female; Genetic Predisposition to Disease; Glucose metabolism; Human Genetics; In Vitro Techniques; Insulin; Insulin - blood; Insulin resistance; Insulin Resistance - genetics; Internal Medicine; Leucine; Leucine - administration & dosage; Leucine - blood; Lipid metabolism; Lipid Metabolism - genetics; Lysine; Male; Medicine; Medicine & Public Health; Metabolic Diseases; Metabolic disorders; Metabolism, Inborn Errors - enzymology; Metabolism, Inborn Errors - genetics; Metabolism, Inborn Errors - physiopathology; Metabolites; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; Mitochondrial Proteins - deficiency; Mitochondrial Proteins - genetics; Original Article; Pediatrics; Phenotype; Post-translation; Protein Processing, Post-Translational; Rodents; Sirtuins - deficiency; Sirtuins - genetics; Up-Regulation; SIRT4; MGcylation; Leucine; C57BL/6J; Sirtuin; 3-methylglutaconylation; Insulin secretion; 3-methylglutarylation; C57BL/6NJ; Post-translational modifications; NNT; Insulin resistance; MGylation; HMGylation; 3-hydroxy- 3-methylglutarylation; Acylation
• ISSN: 0141-8955; 1573-2665; 1573-2665
• DOI: 10.1007/s10545-017-0069-8

Several inherited metabolic disorders are associated with an accumulation of reactive acyl-CoA metabolites that can non-enzymatically react with lysine residues to modify proteins. While the role of acetylation is well-studied, the pathophysiological relevance of more recently discovered acyl modifications, including those found in inherited metabolic disorders, warrants further investigation. We recently showed that sirtuin 4 (SIRT4) removes glutaryl, 3-hydroxy-3-methylglutaryl, 3-methylglutaryl, and 3-methylglutaconyl modifications from lysine residues. Thus, we used SIRT4 knockout mice, which can accumulate these novel post-translational modifications, as a model to investigate their physiological relevance. Since SIRT4 is localized to mitochondria and previous reports have shown SIRT4 influences metabolism, we thoroughly characterized glucose and lipid metabolism in male and female SIRT4KO mice across different genetic backgrounds. While only minor perturbations in overall lipid metabolism were observed, we found SIRT4KO mice consistently had elevated glucose- and leucine-stimulated insulin levels in vivo and developed accelerated age-induced insulin resistance. Importantly, elevated leucine-stimulated insulin levels in SIRT4KO mice were dependent upon genetic background since SIRT4KO mice on a C57BL/6NJ genetic background had elevated leucine-stimulated insulin levels but not SIRT4KO mice on the C57BL/6J background. Taken together, the data suggest that accumulation of acyl modifications on proteins in inherited metabolic disorders may contribute to the overall metabolic dysfunction seen in these patients.