Journal
BIOCHEMICAL JOURNAL
Volume 433, Issue -, Pages 505-514Publisher
PORTLAND PRESS LTD
DOI: 10.1042/BJ20100791
Keywords
cellular metabolism; mitochondrial metabolism; NAD; non-alcoholic fatty liver disease; obesity; proteomics; sirtuin
Categories
Funding
- National Institutes of Health [DK59767, P30-DK48520, K12 HD057022]
- University of Colorado, Center for Human Nutrition [P30-DK048520-09]
- American Heart Association [09BGIA2060705]
- American Diabetes Mentor-based Post-Doctoral Fellowship [7-08-MN-17]
- Veterans Administration
- National Heart, Lung, and Blood Institute
- Center for Cancer Research, National Cancer Institute
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Acetylation has recently emerged as an important mechanism for controlling a broad array of proteins mediating cellular adaptation to metabolic fuels. Acetylation is governed, in part, by SIRTs (sirtuins), class III NAD(+)-dependent deacetylases that regulate lipid and glucose metabolism in liver during fasting and aging. However, the role of acetylation or SIRTs in pathogenic hepatic fuel metabolism under nutrient excess is unknown. In the present study, we isolated acetylated proteins from total liver proteome and observed 193 preferentially acetylated proteins in mice fed on an HFD (high-fat diet) compared with controls, including 11 proteins not previously identified in acetylation studies. Exposure to the HFD led to hyperacetylation of proteins involved in gluconeogenesis, mitochondrial oxidative metabolism, methionine metabolism, liver injury and the ER (endoplasmic reticulum) stress response. Livers of mice fed on the HFD had reduced SIRT3 activity, a 3-fold decrease in hepatic NAD(+) levels and increased mitochondrial protein oxidation. In contrast, neither SIRT1 nor histone acetyltransferase activities were altered, implicating SIRT3 as a dominant factor contributing to the observed phenotype. In Sirt3(-/-) mice, exposure to the HFD further increased the acetylation status of liver proteins and reduced the activity of respiratory complexes III and IV. This is the first study to identify acetylation patterns in liver proteins of HFD-fed mice. Our results suggest that SIRT3 is an integral regulator of mitochondrial function and its depletion results in hyperacetylation of critical mitochondrial proteins that protect against hepatic lipotoxicity under conditions of nutrient excess.
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