Abstract 5177: SIRT2 deacetylates and activates glucose-6-phosphate dehydrogenase (G6PD) to protect cells against oxidative stress.

Abstract

Abstract Glucose-6-phosphate dehydrogenase (G6PD) catalyzes the first committed step in the pentose phosphate pathway (PPP), which converts β-D-glucose-6-phosphate into D-glucono-1,5-lactone-6-phosphate, while concomitantly producing reducing equivalents in the form of NADPH. NADPH is a required cofactor in reductive biosynthesis,and is also required for the generation of reduced glutathione, the major antioxidant responsible for preventing reactive oxygen species (ROS) damage. Lysine acetylation is an evolutionarily conserved post-translational modification in the regulation of a wide range of cellular processes. Several recent acetylome proteomic studies have identified more than 2000 potential acetylation substrates. Among these identified acetylated proteins is G6PD, implicating a novel modulation of G6PD at the post-translational level. However, our knowledge of how acetylation regulates G6PD activity is limited. This study is directed toward to understand the molecular mechanism by which acetylation regulates G6PD function to regulate cellular redox state in response to oxidative stress. Here, we found that G6PD activity is negatively modulated by acetylation, and the major regulated site of acetylation in G6PD was mapped to K403, an evolutionarily conserved lysine residue. Site-specific genetic incorporation of Nε-acetyl-lysine into the position 403 of G6PD revealed that K403 acetylated G6PD is incapable to form active dimers and displays a complete loss in activity. Moreover, we found that the reversible acetylation of K403 is critical to modulate G6PD activity in response to different physiologic conditions, such as high glucose and oxidizing agents. Cytosolic SIRT2 deacetylated G6PD at K403, and greatly restored G6PD activity by inducing the formation of active dimers. Knockdown of endogenous G6PD led to higher cellular susceptibility to oxidant-induced cell death. Re-expression of wild-type G6PD, but not the acetylated mimic G6PDK403Q, could rescue cells from oxidative injury. Together these results uncover a previously unknown mechanism by which SIRT2 deacetylates and activates G6PD and thus protects cells against ROS damage. Citation Format: Yiping Wang, Lisha Zhou, Yuzheng Zhao, Shiwen Wang, Yi Yang, Dan Ye, Yue Xiong, Kun-Liang Guan. SIRT2 deacetylates and activates glucose-6-phosphate dehydrogenase (G6PD) to protect cells against oxidative stress. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5177. doi:10.1158/1538-7445.AM2013-5177 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.