Lee In Hye, Cao Liu, Mostoslavsky Raul, Lombard David B, Liu Jie, Bruns Nicholas E, Tsokos Maria, Alt Frederick W, Finkel Toren
Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3374-9. doi: 10.1073/pnas.0712145105. Epub 2008 Feb 22.
We demonstrate a role for the NAD-dependent deacetylase Sirt1 in the regulation of autophagy. In particular, transient increased expression of Sirt1 is sufficient to stimulate basal rates of autophagy. In addition, we show that Sirt1(-/-) mouse embryonic fibroblasts do not fully activate autophagy under starved conditions. Reconstitution with wild-type but not a deacetylase-inactive mutant of Sirt1 restores autophagy in these cells. We further demonstrate that Sirt1 can form a molecular complex with several essential components of the autophagy machinery, including autophagy genes (Atg)5, Atg7, and Atg8. In vitro, Sirt1 can, in an NAD-dependent fashion, directly deacetylate these components. The absence of Sirt1 leads to markedly elevated acetylation of proteins known to be required for autophagy in both cultured cells and in embryonic and neonatal tissues. Finally, we show that Sirt1(-/-) mice partially resemble Atg5(-/-) mice, including the accumulation of damaged organelles, disruption of energy homeostasis, and early perinatal mortality. Furthermore, the in utero delivery of the metabolic substrate pyruvate extends the survival of Sirt1(-/-) pups. These results suggest that the Sirt1 deacetylase is an important in vivo regulator of autophagy and provide a link between sirtuin function and the overall cellular response to limited nutrients.
我们证明了NAD依赖的脱乙酰酶Sirt1在自噬调节中的作用。具体而言，Sirt1的瞬时表达增加足以刺激基础自噬速率。此外，我们发现Sirt1(-/-)小鼠胚胎成纤维细胞在饥饿条件下不能完全激活自噬。用野生型而非脱乙酰酶失活的Sirt1突变体进行重组可恢复这些细胞中的自噬。我们进一步证明，Sirt1可与自噬机制的几个关键组分形成分子复合物，包括自噬基因（Atg）5、Atg7和Atg8。在体外，Sirt1可以以NAD依赖的方式直接使这些组分脱乙酰化。Sirt1的缺失导致在培养细胞以及胚胎和新生组织中已知自噬所需蛋白质的乙酰化显著升高。最后，我们发现Sirt1(-/-)小鼠部分类似于Atg5(-/-)小鼠，包括受损细胞器的积累、能量稳态的破坏和围产期早期死亡。此外，在子宫内递送代谢底物丙酮酸可延长Sirt1(-/-)幼崽的存活时间。这些结果表明，Sirt1脱乙酰酶是体内自噬的重要调节因子，并在沉默调节蛋白功能与细胞对有限营养的整体反应之间建立了联系。
