TGF-beta inhibits Ang II-induced MAPK p44/42 signaling in vascular smooth muscle cells by Ang II type 1 receptor downregulation.
Vascular changes in diabetes are characterized by reduced vasoconstriction and vascular remodeling. Previously, we demonstrated that TGF-beta1 impairs Ang II-induced contraction through reduced calcium mobilization. However, the effect of TGF-beta1 on Ang II-induced vascular remodeling is unknown. Therefore, we investigated the effect of TGF-beta1 on Ang II-induced activation of the MAPK p44/42 pathway in cultured rat aortic smooth muscle cells (RASMC). Activation of MAPK p44/42 was determined with a phospho-specific antibody. Angiotensin type 1 receptor (AT(1)) and AT(1) mRNA levels were measured by [(3)H]candesartan-binding and real-time PCR, respectively. AT(1) gene transcription activity was assessed using AT(1) promoter-reporter constructs and by a nuclear runoff assay. In TGF-beta1-pretreated cells, Ang II-induced phosphorylation of MAPK p44/42 was inhibited by 29 and 46% for p42 and p44, respectively, and AT(1) density was reduced by 31%. Furthermore, pretreatment with TGF-beta1 resulted in a 64% reduction in AT(1) mRNA levels and decreased AT(1) mRNA transcription rate by 42%. Pretreatment with TGF-beta1 blocked Ang II-induced proliferation of RASMC, while stimulating Ang II-induced upregulation of plasminogen activator inhibitor-1. In conclusion, TGF-beta1 attenuates Ang II-mediated MAPK p44/42 kinase signaling in RASMC through downregulation of AT(1) levels, which is mainly caused by the inhibition of transcription of the AT(1) gene.
Meijering
Bernadet D M
BD
Department of Clinical Pharmacology, Groningen University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
van der Wouden
Els A
EA
Pelgröm
Vincent
V
Henning
Robert H
RH
Sharma
Kumar
K
Deelman
Leo E
LE
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D020871:RNA Stability / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism* / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D053773:Transforming Growth Factor beta1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3