title: Protein kinase B (PKB/AKT1) formed signaling complexes with mitochondrial proteins and prevented glycolytic energy dysfunction in cultured cardiomyocytes during ischemia-reperfusion injury.
abstract: Our previous studies showed that insulin stimulated AKT1 translocation into mitochondria and modulated oxidative phosphorylation complex V in cardiac muscle. This raised the possibility that mitochondrial AKT1 may regulate glycolytic oxidative phosphorylation and mitochondrial function in cardiac muscle cells. The aims of this project were to study the effects of mitochondrial AKT1 signaling on cell survival in stressed cardiomyocytes, to define the effect of mitochondrial AKT1 signaling on glycolytic bioenergetics, and to identify mitochondrial targets of AKT1 signaling in cardiomyocytes. Mitochondrial AKT1 signaling played a protective role against apoptosis and necrosis during ischemia-reperfusion stress, suppressed mitochondrial calcium overload, and alleviated mitochondrial membrane depolarization. Activation of AKT1 signaling in mitochondria increased glucose uptake, enhanced respiration efficiency, reduced superoxide generation, and increased ATP production in the cardiomyocytes. Inhibition of mitochondrial AKT attenuated insulin response, indicating that insulin regulation of ATP production required mitochondrial AKT1 signaling. A proteomic approach was used to reveal 15 novel targets of AKT1 signaling in mitochondria, including pyruvate dehydrogenase complex (PDC). We have confirmed and characterized the association of AKT1 and PDC subunits and verified a stimulatory effect of mitochondrial AKT1 on the enzymatic activity of PDC. These findings suggested that AKT1 formed protein complexes with multiple mitochondrial proteins and improved mitochondrial function in stressed cardiomyocytes. The novel AKT1 signaling targets in mitochondria may become a resource for future metabolism research.
authors.affiliation: University of California Irvine Diabetes Center and Department of Medicine (W.D., H.-B.L., Y.C., Y.-H.C., C.M.E., C.J., P.H.W.), University of California Irvine, California 92697; Department of Medicine (H.-B.L.), Veterans General Hospital, and School of Medicine, National Yang-Ming University, Taipei, 11217, Taiwan; and Departments of Biological Chemistry and Physiology and Biophysics (P.H.W.), University of California Irvine, California 92697.
authors.forename: Wu
authors.initials: W
authors.lastname: Deng
authors.forename: Hsin-Bang
authors.initials: HB
authors.lastname: Leu
authors.forename: Yumay
authors.initials: Y
authors.lastname: Chen
authors.forename: Yu-Han
authors.initials: YH
authors.lastname: Chen
authors.forename: Christine M
authors.initials: CM
authors.lastname: Epperson
authors.forename: Charity
authors.initials: C
authors.lastname: Juang
authors.forename: Ping H
authors.initials: PH
authors.lastname: Wang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015687:Cell Hypoxia; D002478:Cells, Cultured; D006019:Glycolysis; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D021382:Protein Sorting Signals; D021122:Protein Subunits / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D024101:Mitochondrial Proteins; D021382:Protein Sorting Signals; D021122:Protein Subunits; D011768:Pyruvate Dehydrogenase Complex; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; C494920:Akt1 protein, rat; D051057:Proto-Oncogene Proteins c-akt