This work was supported by a National Natural Science Grant (30500237) to Tong Shi.
SIRT3 reduces lipid accumulation via AMPK activation in human hepatic cells
Version of Record online: 3 FEB 2010
© 2010 The Authors. Journal compilation © 2010 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology and Blackwell Publishing Asia Pty Ltd.
Journal of Digestive Diseases
Volume 11, Issue 1, pages 55–62, February 2010
How to Cite
SHI, T., FAN, G. Q. and XIAO, S. D. (2010), SIRT3 reduces lipid accumulation via AMPK activation in human hepatic cells. Journal of Digestive Diseases, 11: 55–62. doi: 10.1111/j.1751-2980.2009.00416.x
- Issue online: 3 FEB 2010
- Version of Record online: 3 FEB 2010
- acetyl coenzyme A carboxylase;
- AMP-activated protein kinase;
- hepatic lipid accumulation;
OBJECTIVE: Sirtuin 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD)+-dependent protein deacetylase localized on mitochondria and regulates the adaptive thermogenesis in brown adipocytes. This study aims to investigate the role of SIRT3 in hepatic lipid accumulation, and whether the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) is required.
METHODS: A retroviral system was used for overexpressing of SIRT3 in HepG2 cells, whereas a lentivirus-mediated vector encoding SIRT3 small interfering RNA (siRNA) was used to infect these cells for knocking down endogenous SIRT3 expression. The cells were treated with oleate to induce lipid accumulation and Nile red staining was used to assess the number of lipid droplets in HepG2 cells. The AMPK signaling pathway was facilitated with the administrating of isoproterenol and an immunoblot analysis was performed to assess the phosphorylation of AMPK and acetyl coenzyme A carboxylase (ACC). Compound C was adopted to inhibit AMPK activity.
RESULTS: The number of lipid droplets in HepG2 cells overexpressing SIRT3 was significantly lower than that in the control cells (P < 0.05). SIRT3-infected cells exhibited significantly more phosphorylation of AMPK and ACC (P < 0.05), which was reversed by the treatment of compound C, an inhibitor of AMPK. Knocking down SIRT3 downregulated phosphorylation of AMPK and ACC by 60–80% (P < 0.05) and promoted lipid accumulation. The activation of AMPK by SIRT3 was dependent on SIRT3 deacetylase activity.
CONCLUSION: SIRT3 reduces lipid accumulation via AMPK activation in human hepatic cells.