title: Oxidative stress stimulates multiple MAPK signalling pathways and phosphorylation of the small HSP27 in the perfused amphibian heart.
abstract: We investigated the activation of three subfamilies of MAPKs (ERK, JNKs and p38-MAPK) by oxidative stress in the isolated perfused amphibian heart. Activation of p43-ERK by 100 micro mol l(-1) H(2)O(2) was maximally observed within 5 min, remained elevated for 30 min and was comparable with the effect of 1 micro mol l(-1) PMA. p43-ERK activation by H(2)O(2) was inhibited by PD98059 but not by SB203580. The p46 and p52 species of JNKs were maximally activated by 2.5- and 2.1-fold, respectively, by 100 micro mol l(-1) H(2)O(2) within 2 min. JNK activation was still detectable after 15 min, reaching control values at 30 min of treatment. p38-MAPK was maximally activated by 9.75-fold by 100 micro mol l(-1) H(2)O(2) after 2 min and this activation progressively declined thereafter, reaching control values within 45 min of treatment. The observed dose-dependent profile of p38-MAPK activation by H(2)O(2) revealed that 30 micro mol l(-1) H(2)O(2) induced maximal phosphorylation, whereas 100-300 micro mol l(-1) H(2)O(2) induced considerable activation of the kinase. Our studies also showed that the phosphorylation of MAPKAPK2 by H(2)O(2) followed a parallel time-dependent pattern and that SB203580 abolished this phosphorylation. Furthermore, our experiments clearly showed that 30 micro mol l(-1) H(2)O(2) induced a strong, specific phosphorylation of HSP27. Our immunohistochemical studies showed that immune complexes of phosphorylated forms of both p38-MAPK and HSP27 were strongly enhanced by 30 micro mol l(-1) H(2)O(2) in the perinuclear region as well as dispersedly in the cytoplasm of ventricular cells and that SB203580 abolished this phosphorylation. These data indicate that oxidative stress is a powerful activator of all three MAPK subfamilies in the amphibian heart. Stimulation of p38-MAPK and the consequent phosphorylation of HSP27 may be important in cardioprotection under such conditions.
authors.affiliation: Department of Animal and Human Physiology, School of Biology, Faculty of Sciences, University of Athens, Panepistimioupolis, Athens 157 84, Greece.
authors.forename: Catherine
authors.initials: C
authors.lastname: Gaitanaki
authors.forename: Stathopoulou
authors.initials: S
authors.lastname: Konstantina
authors.forename: Stavridou
authors.initials: S
authors.lastname: Chrysa
authors.forename: Isidoros
authors.initials: I
authors.lastname: Beis
mesh_terms: D000818:Animals; D004789:Enzyme Activation / Q000502:physiology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D011895:Rana ridibunda
chemical_list: D007093:Imidazoles; D009363:Neoplasm Proteins; D011725:Pyridines; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases; C093642:SB 203580