title: Activation of c-Jun N-terminal kinase promotes survival of cardiac myocytes after oxidative stress.
abstract: Reperfusion injury occurs when ischaemic tissue is reperfused. It involves the generation and release of reactive oxygen that activates numerous signalling pathways and initiates cell death. Exposure of isolated cardiac myocytes to chronic hypoxia followed by reoxygenation results in the early activation of c-Jun N-terminal kinase (JNK) and death by apoptosis of approx. 30% of the myocytes. Although JNK activation has been described in a number of models of ischaemia/reperfusion, the contribution of JNK activation to cell fate has not been established. Here we report that the activation of JNK by reoxygenation correlates with myocyte survival. Transfection of myocytes with JNK pathway interfering plasmid vectors or infection with adenoviral vectors support the hypothesis that JNK is protective. Transfection or infection with JNK inhibitory mutants increased the rates of apoptosis by almost 2-fold compared with control cultures grown aerobically or subjected to hypoxia and reoxygenation. Caspase 9 activity, measured by LEHD cleavage, increased >3-fold during reoxygenation and this activity was enhanced significantly at all times in cultures infected with dominant negative JNK adenovirus. Hypoxia-reoxygenation mediated a biphasic (2.6- and 2.9-fold) activation of p38 mitogen-activated protein kinase, as well as a small increase of tumour necrosis factor alpha (TNFalpha) secretion, but treatments with the p38 MAPK-specific inhibitor SB203580 or saturating levels of a TNFalpha-1 blocking antibody provided only partial protection against apoptosis. The results suggest that JNK activation is protective and that the pathway is largely independent of p38 MAPK or secreted TNFalpha.
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, 1600 NW 10th Avenue, RMSB 6038, Miami, FL 33136, U.S.A.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Dougherty
authors.forename: Lori A
authors.initials: LA
authors.lastname: Kubasiak
authors.forename: Howard
authors.initials: H
authors.lastname: Prentice
authors.forename: Peter
authors.initials: P
authors.lastname: Andreka
authors.forename: Nanette H
authors.initials: NH
authors.lastname: Bishopric
authors.forename: Keith A
authors.initials: KA
authors.lastname: Webster
mesh_terms: D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival; D004789:Enzyme Activation; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000502:physiology; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human