MiPsummer Programme pdf - Mitochondrial Physiology Society

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Abstract # 10
Overexpression of the mitochondrial deacetylase SIRT3 in liver has no effect on metabolic
parameters in mice fed a high fat diet, despite increased oxygen consumption in isolated
hepatocytes
B. Osborne, M. Montgomery, G.J. Cooney, N.Turner
Diabetes & Obesity Program, Garvan Institute of Medical Research, Darlinghurst, NSW 2012,
Australia
Background SIRT3, is a member of the sirtuin family of NAD + -dependent deacylases and the main
mitochondrial deacetylase. SIRT3 has been shown to directly regulate a range of mitochondrial
proteins, suggesting a key role for this enzyme in energy metabolism. Studies in SIRT3 knockout
mice and high fat diet (HFD) fed mice have suggested a link between deleted or low SIRT3 protein
and detrimental metabolic outcomes, including accelerated development of metabolic syndrome 1
and fatty-acid oxidation disorders 2 .
Objectives Given the detrimental effects of SIRT3 deletion, the aim of this study was to determine
if hepatic overexpression of SIRT3 could protect against metabolic defects induced by excess lipid
in mice.
Methods C57BL6 mice were subjected to hydrodynamic tail vein injection of a plasmid containing
SIRT3-FLAG to produce liver-specific overexpression. Primary hepatocytes were isolated and
assessed for oxygen consumption (Seahorse XF Analyzer), triglyceride accumulation, and insulinstimulated
glycogen synthesis, with or without overnight fatty acid treatment. Mice with liver
overexpression of SIRT3 were also maintained on either a chow or high fat diet (HFD) and glucose
tolerance, adiposity and liver triglyceride accumulation were assessed.
Results SIRT3 was effectively overexpressed at both the mRNA and protein level in liver. Isolated
hepatocytes overexpressing SIRT3 showed significantly increased basal oxygen consumption over
controls (>50 percent increase, p