Mitochondrial ROS initiate phosphorylation of p38 MAP kinase during hypoxia in cardiomyocytes.
The p38 mitogen-activated protein kinase (MAPK) is phosphorylated in response to oxidative stress. Mitochondria in cardiomyocytes increase their generation of reactive oxygen species (ROS) during hypoxia (1-5% O(2)). These ROS participate in signal transduction pathways involved in adaptive responses, including ischemic preconditioning and gene transcription. The present study therefore tested the hypothesis that hypoxia induces p38 MAPK phosphorylation by augmenting mitochondrial ROS generation. In cardiomyocytes, phosphorylation of p38 was observed in a PO(2)-dependent manner during hypoxia. This response was inhibited by rotenone, thenoyltrifluoroacetone, and myxothiazol, inhibitors of mitochondrial complexes I, II, and III, respectively. A similar inhibition was observed in the cells pretreated with anion channel inhibitor DIDS, which may block ROS release from mitochondria. During normoxia, increases in mitochondrial ROS elicited by azide (1-2 mM) or by the mitochondrial inhibitor antimycin A caused increased phosphorylation of p38. Brief treatment with exogenous H(2)O(2) during normoxia also induced phosphorylation of p38 as hypoxia, but this effect was not abolished by myxothiazol or DIDS. The antioxidant N-acetyl-cysteine abolished the p38 response to hypoxia, presumably by scavenging H(2)O(2), but the mitogen extracellular receptor kinase inhibitor PD-98059 did not inhibit p38 phosphorylation during hypoxia. Thus physiological hypoxia leads to p38 phosphorylation through a mechanism that requires electron flux in the proximal region of the mitochondrial electron transport chain, which suggests that either H(2)O(2) or superoxide participates in activating that process.
Kulisz
Andre
A
Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, Illinois 60637, USA.
Chen
Ningfang
N
Chandel
Navdeep S
NS
Shao
Zuohui
Z
Schumacker
Paul T
PT
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D002469:Cell Separation; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D002642:Chick Embryo; D015194:Diffusion Chambers, Culture; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014475:Uncoupling Agents / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D000935:Antifungal Agents; D000975:Antioxidants; D001386:Azides; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D016877:Oxidants; D017382:Reactive Oxygen Species; D014475:Uncoupling Agents; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid