title: Differential regulation of p90 ribosomal S6 kinase and big mitogen-activated protein kinase 1 by ischemia/reperfusion and oxidative stress in perfused guinea pig hearts.
abstract: Reactive oxygen species (ROS) activate members of the Src kinase and mitogen-activated protein kinase superfamily, including big mitogen-activated protein kinase 1 (BMK1) and extracellular signal-regulated kinases (ERK1/2). A potentially important downstream effector of ERK1/2 is p90 ribosomal S6 kinase (p90RSK), which plays an important role in cell growth through the activation of several transcription factors, as well as the Na(+)/H(+) exchanger. Previously, we showed that Src regulates BMK1 via a redox-sensitive signaling pathway. Because ROS are generated during ischemia and reperfusion after ischemia, we assessed the effects of these stimuli (H(2)O(2), ischemia, and reperfusion) in the activation of ERK1/2, p90RSK, Src, and BMK1 in perfused guinea pig hearts. H(2)O(2) (100 micromol/L) significantly activated all kinases. Ischemia alone stimulated p90RSK, Src, and BMK1 but not ERK1/2. These results suggest that p90RSK activation through ischemia occurs via a pathway other than ERK1/2. A role of Src in ischemia-mediated BMK1 activation was demonstrated through inhibition with the Src inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine. Reperfusion after ischemia stimulated both p90RSK and ERK1/2. In contrast, although ROS increase during reperfusion after ischemia, the activities of both BMK1 and its upstream regulator, Src, were markedly attenuated by reperfusion after ischemia. The activation of C-terminal Src kinase during ischemia but not during reperfusion suggests that the attenuation of Src and BMK1 activity by reperfusion was not regulated by C-terminal Src kinase activity. The antioxidant N-2-mercaptopropionylglycine completely inhibited ERK1/2 and p90RSK activation by reperfusion but only partially inhibited ischemia-induced Src and BMK1 activation. The present study is the first to show the coregulation of Src and BMK1 by reperfusion after ischemia, which we propose to occur via a novel, ROS-independent pathway.
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
authors.forename: Y
authors.initials: Y
authors.lastname: Takeishi
authors.forename: J i
authors.initials: Ji
authors.lastname: Abe
authors.forename: J D
authors.initials: JD
authors.lastname: Lee
authors.forename: H
authors.initials: H
authors.lastname: Kawakatsu
authors.forename: R A
authors.initials: RA
authors.lastname: Walsh
authors.forename: B C
authors.initials: BC
authors.lastname: Berk
mesh_terms: D000818:Animals; D015971:Gene Expression Regulation, Enzymologic; D006168:Guinea Pigs; D006321:Heart / Q000503:physiopathology*; D008297:Male; D048054:Mitogen-Activated Protein Kinase 7; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D018384:Oxidative Stress; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism*
chemical_list: D019893:Ribosomal Protein S6 Kinases; D048054:Mitogen-Activated Protein Kinase 7; D020928:Mitogen-Activated Protein Kinases