title: AVP inhibits EGF-stimulated MAP kinase cascade in Madin-Darby canine kidney cells.
abstract: We investigated the effects of epidermal growth factor (EGF) and arginine vasopressin (AVP) on Raf-1-MAP kinase cascade, including Raf-1-kinase (Raf-1-K), MAP kinase kinase (MAPKK), MAP kinase (MAPK) and S6 kinase (S6K) in Madin-Darby canine kidney (MDCK) cells. In a dose-dependent manner (10(-10) M to 10(-6) M), EGF increased autophosphorylation of Raf-1-K and activated MAPKK, MAPK and S6K. Sequential activation of these kinases was indicated by their peak times of activation (Raf-1-K 5 min; MAPKK 10 min; MAPK 15 min; and S6K 30 min). AVP (10(-9) M to 10(-6) M) inhibited EGF-stimulated MAP kinase cascade. 8-Bromo-cyclic AMP (cAMP) could mimic the inhibitory effect of AVP on EGF-stimulated MAP kinase cascade. These results were confirmed using H-89, an inhibitor of protein kinase A (PKA) that blocked the effect of AVP on EGF-stimulated MAPK activity. We conclude that AVP inhibits EGF-stimulated Raf-1-K, MAPKK, MAPK, and S6K activity via cAMP in MDCK cells. Our results indicate that MAP kinase cascade may play an important role in integrating the effects of AVP and EGF on distal tubule function.
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D007686:Kidney Tubules, Distal / Q000187:drug effects* / Q000201:enzymology; D020929:Mitogen-Activated Protein Kinase Kinases; D010766:Phosphorylation; D011494:Protein Kinases / Q000187:drug effects / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D019893:Ribosomal Protein S6 Kinases; D013936:Thymidine / Q000378:metabolism
chemical_list: D007529:Isoflavones; D011518:Proto-Oncogene Proteins; D001127:Arginine Vasopressin; D004815:Epidermal Growth Factor; D019833:Genistein; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D019893:Ribosomal Protein S6 Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D013936:Thymidine