Mitochondrial signals initiate the activation of c-Jun N-terminal kinase (JNK) by hypoxia-reoxygenation.
C-Jun N-terminal kinase (JNK) is part of the mitogen-activated protein kinase (MAPK) family of signaling pathways that are induced in response to extracellular stimuli. JNK is primarily a stress-response pathway and can be activated by proinflammatory cytokines and growth factors coupled to membrane receptors or through non-receptor pathways by stimuli such as heat shock, UV irradiation, protein synthesis inhibitors, and conditions that elevate the levels of reactive oxygen intermediates (ROI). The molecular initiators of MAPKs by non-receptor stimuli have not been described. Ischemia followed by reperfusion or hypoxia with reoxygenation represents a condition of high oxidative stress where JNK activation is associated with elevated ROI. We show here that the activation of JNK by this condition is initiated in the mitochondria and requires coupled electron transport, ROI generation, and calcium flux. These signals cause the selective, sequential activation of the calcium-dependent, proline-rich kinase Pyk2 and the small GTP binding factors Rac-1 and Cdc42. Interruption of these interactions with inactivated dominant negative mutant proteins, blocking calcium flux, or inhibiting electron transport through mitochondrial complexes II, III, or IV prevents JNK activation and results in a proapoptotic phenotype that is characteristic of JNK inhibition in this model of ischemia-reperfusion. The signaling pathway is unique for the reoxygenation stimulus and provides a framework for other non-receptor-mediated pathways of MAPK activation.
Dougherty
Christopher J
CJ
Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, Florida 33136, USA.
Kubasiak
Lori A
LA
Frazier
Donna P
DP
Li
Huifang
H
Xiong
Wen-Cheng
WC
Bishopric
Nanette H
NH
Webster
Keith A
KA
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D000968:Antimycin A / Q000494:pharmacology; D017209:Apoptosis; D020013:Calcium Signaling / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D004579:Electron Transport; D004789:Enzyme Activation / Q000187:drug effects; D051418:Focal Adhesion Kinase 2; D006861:Hydrogen Peroxide / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008928:Mitochondria / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000648:ultrastructure; D010101:Oxygen Consumption; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D017382:Reactive Oxygen Species; D000968:Antimycin A; D000841:Anisomycin; D006861:Hydrogen Peroxide; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496054:Ptk2b protein, rat; D048031:JNK Mitogen-Activated Protein Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein