Gbeta gamma mediate differentiation of vascular smooth muscle cells.
Proliferation and subsequent dedifferentiation of vascular smooth muscle (VSM) cells contribute to the pathogenesis of atherosclerosis and postangioplastic restenosis. The dedifferentiation of VSM cells in vivo or in cell culture is characterized by a loss of contractile proteins such as smooth muscle-specific alpha-actin and myosin heavy chain (SM-MHC). Serum increased the expression of contractile proteins in neonatal rat VSM cells, indicating a redifferentiation process. RNase protection assays defined thrombin as a serum component that increases the abundance of SM-MHC transcripts. Additionally, serum and thrombin transiently elevated cytosolic Ca(2+) concentrations, led to a biphasic extracellular signal-regulated kinase (ERK) phosphorylation, up-regulated a transfected SM-MHC promoter construct, and induced expression of the contractile proteins SM-MHC and alpha-actin. Pertussis toxin, N17-Ras/Raf, and PD98059 prevented both the serum- and thrombin-induced second phase ERK phosphorylation and SM-MHC promoter activation. Constitutively active Galpha(q), Galpha(i), Galpha(12), and Galpha(13) failed to up-regulate SM-MHC transcription, whereas Gbetagamma concentration-dependently increased the SM-MHC promoter activity. Furthermore, the Gbetagamma scavenger beta-adrenergic receptor kinase 1 C-terminal peptide abolished the serum-mediated differentiation. We conclude that receptor-mediated differentiation of VSM cells requires Gbetagamma and an intact Ras/Raf/MEK/ERK signaling.
Institute of Clinical Pharmacology and Toxicology and the Institute of Pharmacology, Benjamin Franklin Medical Center, Freie Universität Berlin, Berlin 14195, Germany.
H P
HP
Reusch
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M
Schaefer
C
C
Plum
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G
Schultz
M
M
Paul
D000199:Actins / Q000096:biosynthesis; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D018995:Myosin Heavy Chains / Q000096:biosynthesis; D037342:Pertussis Toxin; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D015398:Signal Transduction; D013917:Thrombin / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000199:Actins; D004791:Enzyme Inhibitors; D005419:Flavonoids; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D012333:RNA, Messenger; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D020928:Mitogen-Activated Protein Kinases; D012260:Ribonucleases; D013917:Thrombin; D018995:Myosin Heavy Chains; D020962:Heterotrimeric GTP-Binding Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium