Angiotensin II type 1 receptor signals through Raf-1 by a protein kinase C-dependent, Ras-independent mechanism.
To understand the molecular mechanism by which the angiotensin II (AII) type 1 receptor (AT1 receptor) transduces its biological signal, we examined the role of various signaling molecules involved in AT1 receptor signaling in Chinese hamster ovary cells stably transfected with the AT1 receptor. AT1 receptor-transfected cells responded to AII treatment by inhibiting adenylyl cyclase, increasing the intracellular Ca2+ concentration, and activating protein kinase C (PKC) alpha and PKC epsilon. AII also activated the c-fos gene and mitogen-activated protein (MAP) kinases. The activation of PKC, the c-fos gene, and MAP kinases was blocked by inhibition of PKC induced by pretreatment with 12-O-tetradecanoylphorbol-13-acetate but not by pretreatment with pertussis toxin, suggesting that PKC couples to the activation of the the c-fos gene and MAP kinases. In addition, AII activated Raf-1 and MAP kinase kinase in a PKC-dependent manner. A dominant negative mutant of Ras had no effect on AII-induced MAP kinase or c-fos gene activation. Thus, the AT1 receptor signals through Raf-1 and its downstream signaling molecules by a PKC-dependent mechanism that does not involve Ras activation.
Arai
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Daiichi Research Center, University of California San Francisco 94143-0130, USA.
Escobedo
J A
JA
D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001011:Aorta; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D016762:Genes, fos; D006801:Humans; D007700:Kinetics; D008156:Luciferases / Q000096:biosynthesis; D020929:Mitogen-Activated Protein Kinase Kinases; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D037342:Pertussis Toxin; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000096:biosynthesis / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015533:Transcriptional Activation; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000096:biosynthesis
D037361:Adenylate Cyclase Toxin; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D011993:Recombinant Fusion Proteins; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D008156:Luciferases; D037342:Pertussis Toxin; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D001616:beta-Galactosidase; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D000262:Adenylyl Cyclases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium