Protein kinase G transmits the cardioprotective signal from cytosol to mitochondria.
Ischemic and pharmacological preconditioning can be triggered by an intracellular signaling pathway in which Gi-coupled surface receptors activate a cascade including phosphatidylinositol 3-kinase, endothelial nitric oxide synthase, guanylyl cyclase, and protein kinase G (PKG). Activated PKG opens mitochondrial KATP channels (mitoKATP) which increase production of reactive oxygen species. Steps between PKG and mitoKATP opening are unknown. We describe effects of adding purified PKG and cGMP on K+ transport in isolated mitochondria. Light scattering and respiration measurements indicate PKG induces opening of mitoKATP similar to KATP channel openers like diazoxide and cromakalim in heart, liver, and brain mitochondria. This effect was blocked by mitoKATP inhibitors 5-hydroxydecanoate, tetraphenylphosphonium, and glibenclamide, PKG-selective inhibitor KT5823, and protein kinase C (PKC) inhibitors chelerythrine, Ro318220, and PKC-epsilon peptide antagonist epsilonV(1-2). MitoKATP are opened by the PKC activator 12-phorbol 13-myristate acetate. We conclude PKG is the terminal cytosolic component of the trigger pathway; it transmits the cardioprotective signal from cytosol to inner mitochondrial membrane by a pathway that includes PKC-epsilon.
Costa
Alexandre D T
AD
Department of Biology, Portland State University, Portland, Ore, USA.
Garlid
Keith D
KD
West
Ian C
IC
Lincoln
Thomas M
TM
Downey
James M
JM
Cohen
Michael V
MV
Critz
Stuart D
SD
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000378:metabolism; D006152:Cyclic GMP / Q000502:physiology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism*; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D010101:Oxygen Consumption; D015221:Potassium Channels / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D000255:Adenosine Triphosphate; D017869:Cyclic GMP-Dependent Protein Kinases; D011493:Protein Kinase C; D006152:Cyclic GMP; D013755:Tetradecanoylphorbol Acetate