title: Oxidative stress contributes to the enhanced expression of Gqα/PLCβ1 proteins and hypertrophy of VSMC from SHR: role of growth factor receptor transactivation.
abstract: We showed previously that vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHRs) exhibit overexpression of Gqα/PLCβ1 proteins, which contribute to increased protein synthesis through the activation of MAP kinase signaling. Because oxidative stress has been shown to be increased in hypertension, the present study was undertaken to examine the role of oxidative stress and underlying mechanisms in enhanced expression of Gqα/PLCβ1 proteins and VSMC hypertrophy. Protein expression was determined by Western blotting, whereas protein synthesis and cell volume, markers for VSMC hypertrophy, were determined by [(3)H]-leucine incorporation and three-dimensional confocal imaging, respectively. The increased expression of Gqα/PLCβ1 proteins, increased protein synthesis, and augmented cell volume exhibited by VSMCs from SHRs were significantly attenuated by antioxidants N-acetyl-cysteine (NAC), a scavenger of superoxide anion, DPI, an inhibitor of NAD(P)H oxidase. In addition, PP2, AG1024, AG1478, and AG1295, inhibitors of c-Src, insulin-like growth factor receptor (IGFR), epidermal growth factor receptor (EGFR), and platelet-derived growth factor receptor (PDGFR), respectively, also attenuated the enhanced expression of Gqα/PLCβ1 proteins and enhanced protein synthesis in VSMCs from SHRs toward control levels. Furthermore, the levels of IGF-1R and EGFR proteins and not of PDGFR were also enhanced in VSMCs from SHRs, which were attenuated significantly by NAC, DPI, and PP2. In addition, NAC, DPI, and PP2 also attenuated the enhanced phosphorylation of IGF-1R, PDGFR, EGFR, c-Src, and EKR1/2 in VSMCs from SHRs. These data suggest that enhanced oxidative stress in VSMCs from SHRs activates c-Src, which through the transactivation of growth factor receptors and MAPK signaling contributes to enhanced expression of Gqα/PLCβ1 proteins and resultant VSMC hypertrophy.
authors.affiliation: Department of Molecular and Integrative Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada.
authors.forename: Mohammed Emehdi
authors.initials: ME
authors.lastname: Atef
authors.affiliation: Department of Molecular and Integrative Physiology, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada madhu.anand-srivastava@umontreal.ca.
authors.forename: Madhu B
authors.initials: MB
authors.lastname: Anand-Srivastava
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D048429:Cell Size; D002478:Cells, Cultured; D004195:Disease Models, Animal; D066246:ErbB Receptors / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D006973:Hypertension / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D006984:Hypertrophy; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D054799:Phospholipase C beta / Q000378:metabolism*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000378:metabolism; D034622:RNA Interference; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D047428:Protein Kinase Inhibitors; D017978:Receptors, Growth Factor; C483803:Egfr protein, rat; D066246:ErbB Receptors; D017526:Receptor, IGF Type 1; D017479:Receptors, Platelet-Derived Growth Factor; D016392:Proto-Oncogene Proteins pp60(c-src); D020928:Mitogen-Activated Protein Kinases; D054799:Phospholipase C beta; C518035:Plcb1 protein, rat; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: Gqα/PLCβ1; SHR; VSMC; hypertrophy; oxidative stress