The proliferation of vascular smooth muscle cells is important in the pathogenesis of many vascular diseases. Reactive oxygen species (ROS) produced by NADPH oxidases in smooth muscle cells have been shown to participate in signaling cascades regulating proliferation induced by platelet-derived growth factor (PDGF), a powerful smooth muscle mitogen. We sought to determine the role of Nox5 in the regulation of PDGF-stimulated human aortic smooth muscle cell (HASMC) proliferation. Cultured HASMC were found to express four isoforms of Nox5. When HASMC stimulated with PDGF were pretreated with N-acetyl cysteine (NAC), proliferation was significantly reduced. Proliferation induced by PDGF was also heavily dependent on JAK/STAT activation, as the JAK inhibitor, AG490, was able to completely abolish PDGF-stimulated HASMC growth. Specific knockdown of Nox5 with a siRNA strategy reduced PDGF-induced HASMC ROS production and proliferation. Additionally, siRNA to Nox5 inhibited PDGF-stimulated JAK2 and STAT3 phosphorylation. ROS produced by Nox5 play an important role in PDGF-induced JAK/STAT activation and HASMC proliferation.
KeywordsNADPH oxidase; reactive oxygen species; Nox5; vascular smooth muscle cells; proliferation In atherosclerosis and restenosis after percutaneous coronary intervention, cytokines elaborated by both vascular cells and cells invading the vessel wall induce vascular smooth muscle proliferation and contribute to lesion formation. In the normal vessel wall, smooth muscle cells (SMCs) maintain and regulate vascular tone. However, VSMCs change their phenotype to a synthetic, proliferative state when stimulated by a number of different growth factors.One such growth factor, platelet-derived growth factor (PDGF), is expressed by all vascular cell types [1,2] and by invading inflammatory cells, such as monocytes and lymphocytes, in atherosclerosis [1]. PDGF has long been recognized as a powerful VSMC mitogen [3] and the induction of PDGF receptors in VSMCs during atherogenesis has been demonstrated in several studies [4,5]. Blockade of PDGF, whether by anti-PDGF antibody [6][7][8], PDGF receptor antisense therapy [9,10], or chimeric knockout in mice [11], reduces lesion formation after vascular injury. Ligand binding to the PDGF receptor causes tyrosine autophosphorylation and Address correspondence to: Kathy K. Griendling, Emory University, Division of Cardiology, 319 WMB, 1639 Pierce Dr., Atlanta, GA 30322,, e-mail: kgriend@emory.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. With regard to PDGF signaling, Nox5 is of particular interest because it...
