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SIRT3 通过激活 AMPK 减少人肝细胞中的脂质积累。

SIRT3 reduces lipid accumulation via AMPK activation in human hepatic cells.

机构信息

Shanghai Institute of Digestive Disease, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.

出版信息

J Dig Dis. 2010 Feb;11(1):55-62. doi: 10.1111/j.1751-2980.2009.00416.x.

DOI:10.1111/j.1751-2980.2009.00416.x

PMID:20132432

Abstract

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.

摘要

目的

Sirtuin 3（SIRT3）是一种烟酰胺腺嘌呤二核苷酸（NAD）（+）依赖性蛋白去乙酰化酶，位于线粒体中，调节棕色脂肪细胞的适应性产热。本研究旨在探讨 SIRT3 在肝脂质积累中的作用，以及是否需要激活腺苷一磷酸（AMP）激活的蛋白激酶（AMPK）。

方法

使用逆转录病毒系统在 HepG2 细胞中过表达 SIRT3，而慢病毒介导的载体编码 SIRT3 小干扰 RNA（siRNA）用于感染这些细胞以敲低内源性 SIRT3 表达。用油酸盐处理细胞以诱导脂质积累，并使用尼罗红染色评估 HepG2 细胞中的脂质滴数量。用异丙肾上腺素促进 AMPK 信号通路，并用免疫印迹分析评估 AMPK 和乙酰辅酶 A 羧化酶（ACC）的磷酸化。采用化合物 C 抑制 AMPK 活性。

结果

过表达 SIRT3 的 HepG2 细胞中的脂质滴数量明显低于对照细胞（P<0.05）。感染 SIRT3 的细胞中 AMPK 和 ACC 的磷酸化明显增加（P<0.05），用 AMPK 抑制剂化合物 C 处理可逆转这种情况。敲低 SIRT3 可使 AMPK 和 ACC 的磷酸化降低 60-80%（P<0.05）并促进脂质积累。SIRT3 通过 SIRT3 脱乙酰酶活性激活 AMPK。