Protein kinase B (PKB/AKT1) formed signaling complexes with mitochondrial proteins and prevented glycolytic energy dysfunction in cultured cardiomyocytes during ischemia-reperfusion injury

Endocrinology. 2014 May;155(5):1618-28. doi: 10.1210/en.2013-1817. Epub 2014 Mar 6.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Animals, Newborn
  • Apoptosis
  • Cell Hypoxia
  • Cells, Cultured
  • Glycolysis*
  • Mitochondria / metabolism
  • Mitochondrial Proteins / antagonists & inhibitors
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Myocardial Reperfusion Injury / metabolism*
  • Myocardial Reperfusion Injury / pathology
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • Protein Sorting Signals
  • Protein Subunits / agonists
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Protein Transport
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Pyruvate Dehydrogenase Complex / chemistry
  • Pyruvate Dehydrogenase Complex / genetics
  • Pyruvate Dehydrogenase Complex / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Signal Transduction*

Substances

  • Mitochondrial Proteins
  • Protein Sorting Signals
  • Protein Subunits
  • Pyruvate Dehydrogenase Complex
  • Recombinant Proteins
  • Adenosine Triphosphate
  • Akt1 protein, rat
  • Proto-Oncogene Proteins c-akt