title: Mitochondrial PKC-ε deficiency promotes I/R-mediated myocardial injury via GSK3β-dependent mitochondrial permeability transition pore opening.
abstract: Mitochondrial fission is critically involved in cardiomyocyte apoptosis, which has been considered as one of the leading causes of ischaemia/reperfusion (I/R)-induced myocardial injury. In our previous works, we demonstrate that aldehyde dehydrogenase-2 (ALDH2) deficiency aggravates cardiomyocyte apoptosis and cardiac dysfunction. The aim of this study was to elucidate whether ALDH2 deficiency promotes mitochondrial injury and cardiomyocyte death in response to I/R stress and the underlying mechanism. I/R injury was induced by aortic cross-clamping for 45 min. followed by unclamping for 24 hrs in ALDH2 knockout (ALDH2-/-) and wild-type (WT) mice. Then myocardial infarct size, cell apoptosis and cardiac function were examined. The protein kinase C (PKC) isoform expressions and their mitochondrial translocation, the activity of dynamin-related protein 1 (Drp1), caspase9 and caspase3 were determined by Western blot. The effects of N-acetylcysteine (NAC) or PKC-δ shRNA treatment on glycogen synthase kinase-3β (GSK-3β) activity and mitochondrial permeability transition pore (mPTP) opening were also detected. The results showed that ALDH2-/-mice exhibited increased myocardial infarct size and cardiomyocyte apoptosis, enhanced levels of cleaved caspase9, caspase3 and phosphorylated Drp1. Mitochondrial PKC-ε translocation was lower in ALDH2-/-mice than in WT mice, and PKC-δ was the opposite. Further data showed that mitochondrial PKC isoform ratio was regulated by cellular reactive oxygen species (ROS) level, which could be reversed by NAC pre-treatment under I/R injury. In addition, PKC-ε inhibition caused activation of caspase9, caspase3 and Drp1Ser616in response to I/R stress. Importantly, expression of phosphorylated GSK-3β (inactive form) was lower in ALDH2-/-mice than in WT mice, and both were increased by NAC pre-treatment. I/R-induced mitochondrial translocation of GSK-3β was inhibited by PKC-δ shRNA or NAC pre-treatment. In addition, mitochondrial membrane potential (∆Ψm) was reduced in ALDH2-/-mice after I/R, which was partly reversed by the GSK-3β inhibitor (SB216763) or PKC-δ shRNA. Collectively, our data provide the evidence that abnormal PKC-ε/PKC-δ ratio promotes the activation of Drp1 signalling, caspase cascades and GSK-3β-dependent mPTP opening, which results in mitochondrial injury-triggered cardiomyocyte apoptosis and myocardial dysfuction in ALDH2-/-mice following I/R stress.
authors.affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Shijun
authors.initials: S
authors.lastname: Wang
authors.affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Heart Centre of Zhengzhou Ninth People's Hospital, Zhengzhou, Henan, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Institute of Clinical Medicine and Department of Cardiology, Renmin Hospital, Hubei University of Medicine, Shiyan, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: Institute of Clinical Medicine and Department of Cardiology, Renmin Hospital, Hubei University of Medicine, Shiyan, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.affiliation: Institute of Clinical Medicine and Department of Cardiology, Renmin Hospital, Hubei University of Medicine, Shiyan, China.
authors.forename: You-En
authors.initials: YE
authors.lastname: Zhang
mesh_terms: D000071396:Aldehyde Dehydrogenase, Mitochondrial / Q000172:deficiency / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D004789:Enzyme Activation; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000201:enzymology*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D008954:Models, Biological; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D051745:Protein Kinase C-delta / Q000378:metabolism; D051744:Protein Kinase C-epsilon / Q000172:deficiency* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D007527:Isoenzymes; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D017382:Reactive Oxygen Species; C515029:ALDH2 protein, mouse; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D000071679:Glycogen Synthase Kinase 3 beta; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon
keywords: 
  PKC
  ; Drp1; GSK-3β; Ischaemia/reperfusion injury; Mitochondrial oxidative stress