title: Mechanical stretch stimulates growth of vascular smooth muscle cells via epidermal growth factor receptor.
abstract: We have studied whether activation of epidermal growth factor receptor (EGFR) is involved in stretch-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation and protein synthesis in cultured rat vascular smooth muscle cells (VSMC). Cyclic stretch (1 Hz) induced a rapid (within 5 min) phosphorylation of ERK1/2, an effect that was time and strength dependent and inhibited by an EGFR kinase inhibitor (AG-1478) but not by a platelet-derived growth factor receptor kinase inhibitor (AG-1296). The stretch rapidly (within 2 min) induced tyrosine phosphorylation of several proteins, among which 180-kDa protein was shown to be EGFR as revealed by blockade with AG-1478 as well as immunoprecipitation with anti-EGFR antibody coupled with immunoblotting with anti-phosphotyrosine antibody. The stretch rapidly (within 2 min) induced association of tyrosine-phosphorylated EGFR with adaptor proteins (Shc/Grb2) as revealed by coprecipitation with glutathione-S-transferase-Grb2 fusion protein coupled with immunoblotting with anti-phosphotyrosine, anti-EGFR, and anti-Shc antibodies. Transfection of a dominant-negative mutant of H-Ras also inhibited stretch-induced ERK1/2 activation. Treatment with a stretch-activated ion channel blocker (Gd(3+)) and an intracellular Ca(2+) antagonist (TMB-8) inhibited stretch-induced phosphorylation of EGFR and ERK1/2. Treatment with AG-1478 and a mitogen-activated protein kinase kinase inhibitor (PD-98059), but not AG-1296, blocked [(3)H]leucine uptake stimulated by a high level of stretch. These data suggest that ERK1/2 activation by mechanical stretch requires Ca(2+)-sensitive EGFR activation mainly via stretch-activated ion channels, thereby leading to VSMC growth.
authors.affiliation: Division of Endocrinology and Metabolism, Second Department of Internal Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iwasaki
authors.forename: S
authors.initials: S
authors.lastname: Eguchi
authors.forename: H
authors.initials: H
authors.lastname: Ueno
authors.forename: F
authors.initials: F
authors.lastname: Marumo
authors.forename: Y
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology*; D051380:GRB2 Adaptor Protein; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology; D010766:Phosphorylation; D010812:Physical Stimulation; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D011799:Quinazolines; D051381:Rats; D017207:Rats, Sprague-Dawley; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014443:Tyrosine / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004791:Enzyme Inhibitors; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D011506:Proteins; D011799:Quinazolines; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D020032:Tyrphostins; C101044:RTKI cpd; D014443:Tyrosine; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras); D002118:Calcium