Oxidant-induced activation of type I protein kinase A is mediated by RI subunit interprotein disulfide bond formation.
Here we demonstrate that type I protein kinase A is redoxactive, forming an interprotein disulfide bond between its two regulatory RI subunits in response to cellular hydrogen peroxide. This oxidative disulfide formation causes a subcellular translocation and activation of the kinase, resulting in phosphorylation of established substrate proteins. The translocation is mediated at least in part by the oxidized form of the kinase having an enhanced affinity for alpha-myosin heavy chain, which serves as a protein kinase A (PKA) anchor protein and localizes the PKA to its myofilament substrates troponin I and myosin binding protein C. The functional consequence of these events in cardiac myocytes is that hydrogen peroxide increases contractility independently of beta-adrenergic stimulation and elevations of cAMP. The oxidant-induced phosphorylation of substrate proteins and increased contractility is blocked by the kinase inhibitor H89, indicating that these events involve PKA activation. In essence, type I PKA contains protein thiols that operate as redox sensors, and their oxidation by hydrogen peroxide directly activates the kinase.
Brennan
Jonathan P
JP
Department of Cardiology, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Bardswell
Sonya C
SC
Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Burgoyne
Joseph R
JR
Department of Cardiology, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Fuller
William
W
Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Schröder
Ewald
E
Department of Cardiology, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Wait
Robin
R
Kennedy Institute of Rheumatology Division, Faculty of Medicine, Imperial College London, 1, Aspenlea Rd., Hammersmith, London, W6 8LH United Kingdom.
Begum
Shajna
S
Kennedy Institute of Rheumatology Division, Faculty of Medicine, Imperial College London, 1, Aspenlea Rd., Hammersmith, London, W6 8LH United Kingdom.
Kentish
Jonathan C
JC
Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH.
Eaton
Philip
P
Department of Cardiology, The Rayne Institute, St. Thomas' Hospital, London, SE1 7EH. Electronic address: philip.eaton@kcl.ac.uk.
D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004220:Disulfides; D004789:Enzyme Activation / Q000187:drug effects; D006321:Heart; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D021122:Protein Subunits; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D024723:Ventricular Myosins
D004220:Disulfides; D016877:Oxidants; D021122:Protein Subunits; D006861:Hydrogen Peroxide; D017868:Cyclic AMP-Dependent Protein Kinases; D024723:Ventricular Myosins