AMP-activated protein kinase protects against necroptosis via regulation of Keap1-PGAM5 complex

Background: The AMP-activated protein kinase (AMPK) plays critical roles in growth regulation and metabolism reprogramming. AMPK activation protects cells against apoptosis frominjury in different cell and animal models. However, its function in necroptosis remains largely unclear. Methods and results: In the current study, we demonstrated that AMPKwas activated upon necroptosis induction and protected mouse embryonic fibroblasts (MEFs) and cardiomyocytes from N-methyl-N'-nitro-Nnitrosoguanidine (MNNG) and reactive oxygen species (ROS) induced necroptosis. Activation of AMPK with chemicals A-769662, 2-deoxyglucose (2-DG), and metformin or constitutively active (CA) AMPK markedly decreased necroptosis and cytotoxicity induced by MNNG. In contrast, AMPK inhibitor compound C, dominant negative (DN) AMPK, as well as AMPK shRNAs increased necroptosis and cytotoxicity induced byMNNG. We further showed that AMPK physically associated with a protein complex containing PGAM5 and Keap1 whereby facilitating Keap1-mediated PGAM5 ubiquitination upon necroptosis induction. TheAMPK agonistmetforminameliorated myocardial ischemia and reperfusion (IR) injury and reduced necroptosis through down-regulating the expression of PGAM5 in the Langendorff-perfused rat hearts. Conclusion: Activation ofAMPK protects against necroptosis via promoting Keap1-mediated PGAM5degradation. Metformin may act as a valuable agent for the protection of myocardial ischemia and reperfusion injury by activating AMPK and reducing necroptosis. (c) 2018 Published by Elsevier B.V.