p38 Mitogen-activated Protein Kinase Is a Critical Component of the Redox-sensitive Signaling Pathways Activated by Angiotensin II
ROLE IN VASCULAR SMOOTH MUSCLE CELL HYPERTROPHY*
Abstract
Angiotensin II induces an oxidant stress-dependent hypertrophy in cultured vascular smooth muscle cells. To investigate the growth-related molecular targets of H2O2, we examined the redox sensitivity of agonist-stimulated activation of the mitogen-activated protein kinase (MAPK) family. We show here that angiotensin II elicits a rapid increase in intracellular H2O2 and a rapid and robust phosphorylation of both p42/44MAPK (16-fold) and p38MAPK (15-fold). However, exogenous H2O2 activates only p38MAPK (14-fold), and diphenylene iodonium, an NADH/NADPH oxidase inhibitor, attenuates angiotensin II-stimulated phosphorylation of p38MAPK, but not p42/44MAPK. Furthermore, in cells stably transfected with human catalase, angiotensin II-induced intracellular H2O2 generation is almost completely blocked, resulting in inhibition of phosphorylation of p38MAPK, but not p42/44MAPK, and a subsequent partial decrease in angiotensin II-induced hypertrophy. Specific inhibition of either the p38MAPK pathway with SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole) or the p42/44MAPK pathway with PD98059 (2-(2′-amino-3′-methoxyphenyl)oxanaphthalen-4-one) also partially, but significantly, attenuates angiotensin II-induced hypertrophy; however, simultaneous blockade of both pathways has an additive inhibitory effect, indicating that the hypertrophic response to angiotensin II requires parallel, independent activation of both MAPK pathways. These results provide the first evidence that p38MAPK is a critical component of the oxidant stress (H2O2)-sensitive signaling pathways activated by angiotensin II in vascular smooth muscle cells and indicate that it plays a crucial role in vascular hypertrophy.
Footnotes
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↵* This work was supported by National Institutes of Health Grant HL38206.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed: Division of Cardiology, Emory University School of Medicine, 1639 Pierce Dr., Rm. 319, Atlanta, GA 30322. Tel.: 404-727-8142; Fax: 404-727-3330; E-mail:mfukai{at}emory.edu.
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↵1 The abbreviations used are: VSMCs, vascular smooth muscle cells; Ang II, angiotensin II; O⨪2, superoxide; MAPK, mitogen-activated protein kinase; ERK1/2, extracellular signal-regulated kinase 1 and 2; JNK, c-Jun NH2-terminal kinases; SAPK, stress-activated protein kinase; p38MAPK, 38-kDa MAPK; BMK-1, Big MAPK-1; p90rsk, 90-kDa ribosomal S6 kinase; ATF, activating transcription factor; CHOP, C/EBP-homologous protein; MEF2C, myocyte enhancer binding factor-2C; MAPKAP kinase 2/3, MAPK-activated protein kinase 2 or 3; HSP, heat shock protein; MEK, MAPK/ERK kinase; HRP, horseradish peroxidase; DMEM, Dulbecco’s modified Eagle’s medium; PBS, phosphate-buffered saline; ECL, enhanced chemiluminescence; DCF-DA, 2′,7′-dichlorofluorscein diacetate; DPI, diphenylene iodonium; SB203580, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; PD98059, 2-(2′-amino-3′-methoxyphenyl)oxanaphthalen-4-one; MAPKKK, MAPK kinase kinase; MKK3/6, MAPK kinase 3 or 6; PAK-1, p21-activated kinase-1; p70S6K, 70-kDa ribosomal S6 kinase; PAGE, polyacrylamide gel electrophoresis.
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- Received January 2, 1998.
- Revision received March 25, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
