p22phox Is a Critical Component of the Superoxide-generating NADH/NADPH Oxidase System and Regulates Angiotensin IIinduced Hypertrophy in Vascular Smooth Muscle Cells*
- ‡To whom correspondence should be addressed: Division of Cardiology, Emory University of School of Medicine, 319 WMB, 1639 Pierce Dr., Atlanta, GA 30322. Tel.: 404-727-8168; Fax: 404-727-3330; E-mail: kgriend{at}emory.edu.
Abstract
Superoxide anion formation is vital to the microbicidal activity of phagocytes. Recently, however, there is accumulating evidence that it is also involved in cell growth in vascular smooth muscle cells (VSMCs). We have shown that the hypertrophic agent angiotensin II stimulates superoxide production by activating the membrane-bound NADH/NADPH oxidase and that inhibition of this oxidase attenuates vascular hypertrophy. However, the molecular identity of this oxidase in VSMCs is unknown. We have recently cloned the cytochrome b558 α-subunit, p22phox (one of the key electron transfer elements of the NADPH oxidase in phagocytes), from a rat VSMC cDNA library, but its role in VSMC oxidase activity remains unclarified. Here we report that the complete inhibition of p22phox mRNA expression by stable transfection of antisense p22phox cDNA into VSMCs results in a decrease in cytochrome b content, which is accompanied by a significant inhibition of angiotensin II-stimulated NADH/NADPH-dependent superoxide production, subsequent hydrogen peroxide production, and [3H]leucine incorporation. We provide the first evidence that p22phox is a critical component of superoxide-generating vascular NADH/NADPH oxidase and suggest a central role for this oxidase system 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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↵1 The abbreviations used are:
- VSMC
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vascular smooth muscle cell
- Ang II
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angiotensin II
- O
2 -
superoxide anion
- H2O2
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hydrogen peroxide
- DMEM
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Dulbecco's modified Eagle's medium
- DPI
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diphenylene iodonium
- DCF-DA
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2′,7′-dichlorofluorescein diacetate.
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↵2T. Fukui, S. Rajagopalan, N. Ishizaka, J. B. Laursen, Q. Capers IV, W. R. Taylor, D. G. Harrison, H. D. Leon, J. N. Wilcox, and K. K. Griendling, unpublished observations.
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- Received June 11, 1996.
- Revision received July 17, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
