SIRT1 Positively Regulates Autophagy and Mitochondria Function in Embryonic Stem Cells Under Oxidative Stress. (May 2014)

• Record Type: Journal Article
• Authors: Ou, Xuan; Lee, Man Ryul; Huang, Xinxin; Messina‐Graham, Steven; Broxmeyer, Hal E.
• Is Part Of: Stem cells. Volume 32:Number 5(2014:May)
• Page Start: 1183
• Page End: 1194
• Publication Date: 2014-05
• Subjects: Cloning -- Periodicals; Clone cells -- Periodicals; Stem cells -- Periodicals; Cell Differentiation -- Periodicals; Cell Division -- Periodicals; Clone Cells -- Periodicals; Hematopoietic Stem Cells -- Periodicals; Stem Cells -- Periodicals; 571.84
• DOI: 10.1002/stem.1641
• Languages: English
• ISSNs: 1066-5099

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>SIRT1, an NAD‐dependent deacetylase, plays a role in regulation of autophagy. SIRT1 increases mitochondrial function and reduces oxidative stress, and has been linked to age‐related reactive oxygen species (ROS) generation, which is highly dependent on mitochondrial metabolism. H<sub>2</sub>O<sub>2</sub> induces oxidative stress and autophagic cell death through interference with Beclin 1 and the mTOR signaling pathways. We evaluated connections between SIRT1 activity and induction of autophagy in murine (m) and human (h) embryonic stem cells (ESCs) upon ROS challenge. Exogenous H<sub>2</sub>O<sub>2</sub> (1 mM) induced apoptosis and autophagy in wild‐type (WT) and <italic>Sirt1−/−</italic> mESCs. High concentrations of H<sub>2</sub>O<sub>2</sub> (1 mM) induced more apoptosis in <italic>Sirt1−/−</italic>, than in WT mESCs. However, addition of 3‐methyladenine, a widely used autophagy inhibitor, in combination with H<sub>2</sub>O<sub>2</sub> induced more cell death in WT than in <italic>Sirt1−/−</italic> mESCs. Decreased induction of autophagy in <italic>Sirt1−/−</italic> mESCs was demonstrated by decreased conversion of LC3‐I to LC3‐II, lowered expression of Beclin‐1, and decreased LC3 punctae and LysoTracker staining. H<sub>2</sub>O<sub>2</sub> induced autophagy with loss of mitochondrial membrane potential and disruption of mitochondrial dynamics in <italic>Sirt1−/−</italic> mESCs. Increased phosphorylation of P70/85‐S6 kinase and ribosomal S6 was noted in <italic>Sirt1−/−</italic> mESCs, suggesting that SIRT1 regulates the mTOR pathway. Consistent with effects in mESCs, inhibition of <italic>SIRT1</italic> using <italic>Lentivirus</italic>‐mediated <italic>SIRT1 shRNA</italic> in hESCs demonstrated that knockdown of <italic>SIRT1</italic> decreased <italic>H<sub>2</sub>O<sub>2</sub>‐induced</italic> autophagy. This suggests a role for SIRT1 in regulating autophagy and mitochondria function in ESCs upon oxidative stress, effects mediated at least in part by the class III PI3K/Beclin 1 and mTOR pathways. S<sc>tem</sc> C<sc>ells</sc><italic>2014;32:1183–1194</italic></p> </abstract>