Small GTP binding protein Ras contributes to norepinephrine-induced mitogenesis of vascular smooth muscle cells.
Norepinephrine stimulates release of arachidonic acid from tissue lipids. Arachidonic acid metabolites generated through the lipoxygenase and cytochrome P-450 pathways but not cyclooxygenase stimulate mitogen activated protein (MAP) kinase activity and proliferation of vascular smooth muscle cells (VSMC). Moreover, norepinephrine has been shown to activate the Ras/MAP kinase pathway through generation of cytochrome P450 metabolite of arachidonic acid, 20-hydroxyeicosatetraenoic acid (20-HETE). The purpose of this study was to investigate the contribution of Ras in norepinephrine-induced mitogenesis in aortic VSMC. Farnesylation of Ras by farnesyl transferase is required for its full activation. Norepinephrine-induced DNA synthesis, as measured by [3H]-thymidine incorporation, was attenuated by inhibitors of Ras farnesyl transferase FPT III and BMS-191563. These agents also inhibited 20-HETE-stimulated [3H]-thymidine incorporation. In cells transiently transfected with dominant negative Ras (RasN17), norepinephrine, and 20-HETE-induced proliferation of VSMC was attenuated. Both norepinephrine and 20-HETE increased localization of Ras to plasma membrane and MAP kinase activity; FPT III attenuated these effects. These data suggest that VSMC proliferation induced by norepinephrine and 20-HETE is mediated by Ras/MAP kinase pathway.
Muthalif
M M
MM
Department of Pharmacology, College of Medicine, The University of Tennessee, Memphis 38163, USA.
Uddin
M R
MR
Fatima
S
S
Parmentier
J H
JH
Khandekar
Z
Z
Malik
K U
KU
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051231:Farnesyltranstransferase; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D009638:Norepinephrine / Q000494:pharmacology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018631:ras Proteins / Q000502:physiology*
D004791:Enzyme Inhibitors; D019883:Alkyl and Aryl Transferases; D051231:Farnesyltranstransferase; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins; D009638:Norepinephrine