title: Agonist stimulation of Na+/K+/Cl- cotransport in rat glomerular mesangial cells. Evidence for protein kinase C-dependent and Ca2+/calmodulin-dependent pathways.
abstract: Studies were performed to investigate regulatory pathways of loop diuretic-sensitive Na+/K+/Cl- cotransport in cultured rat glomerular mesangial cells. Angiotensin II, alpha-thrombin, and epidermal growth factor (EGF) all stimulated Na+/K+/Cl- cotransport in a concentration-dependent manner. Pertussis toxin pretreatment reduced the effects of angiotensin II and alpha-thrombin but not that of EGF. Addition of the protein kinase C inhibitor staurosporine or down-regulation of protein kinase C by prolonged incubation with phorbol 12-myristate 13-acetate partially reduced the effects of angiotensin II and alpha-thrombin and completely blunted the phorbol 12-myristate 13-acetate-induced stimulation of Na+/K+/Cl- cotransport but did not affect EGF-induced stimulation. Exposure of cells to a calcium ionophore, A23187, resulted in a concentration-dependent stimulation of Na+/K+/Cl- cotransport, which was not significantly inhibited by down-regulation of protein kinase C but was completely inhibited by the calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). Stimulation of the cotransport by angiotensin II or alpha-thrombin was also partially inhibited by W-7. Inhibitory effects of protein kinase C down-regulation and W-7 were additive and, when combined, produced a complete inhibition of angiotensin II-induced stimulation of Na+/K+/Cl- cotransport. In saponin-permeabilized mesangial cells, phosphorylation of a synthetic decapeptide substrate for Ca2+/calmodulin-dependent kinase II, Pro-Leu-Ser-Arg-Thr-Leu-Ser-Val-Ser-Ser-NH3, was demonstrated. Maximal activation of the decapeptide substrate phosphorylation required the presence of Ca2+ and calmodulin and was dependent on Ca2+ concentration. These findings indicate that stimulation of Na+/K+/Cl- cotransport by angiotensin II and alpha-thrombin is mediated by protein kinase C and Ca2+/calmodulin-dependent kinases whereas the action of EGF is mediated by other pathways.
authors.affiliation: Department of Medicine, Veterans Administration Medical Center, Nashville, Tennessee.
authors.forename: T
authors.initials: T
authors.lastname: Homma
authors.forename: K D
authors.initials: KD
authors.lastname: Burns
authors.forename: R C
authors.initials: RC
authors.lastname: Harris
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005920:Glomerular Mesangium / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis; D037342:Pertussis Toxin; D011188:Potassium / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D028021:Sodium-Potassium-Chloride Symporters; D019311:Staurosporine; D013379:Substrate Specificity; D013449:Sulfonamides / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D002352:Carrier Proteins; D002712:Chlorides; D009842:Oligopeptides; D047428:Protein Kinase Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D013449:Sulfonamides; D010566:Virulence Factors, Bordetella; D000804:Angiotensin II; D000001:Calcimycin; D004815:Epidermal Growth Factor; C017967:W 7; D012964:Sodium; D037342:Pertussis Toxin; D011494:Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D013917:Thrombin; D019311:Staurosporine; D011188:Potassium