title: Inhibition of calcineurin phosphatase promotes exocytosis of renin from juxtaglomerular cells.
abstract: To examine the role of the calcium/calmodulin-dependent phosphatase calcineurin in regulation of renin release, we assayed exocytosis using whole-cell patch clamp of single juxtaglomerular cells in culture. The calcineurin inhibitor, cyclosporine A (CsA), significantly increased juxtaglomerular cell membrane capacitance, an index of cell surface area and an established measure of exocytosis in single-cell assays. This effect was mimicked by intracellular delivery of a calcineurin inhibitory peptide, the calcium chelator ethylene glycol tetraacetic acid (EGTA), or the calmodulin inhibitor W-13. Simultaneous exposure to EGTA and CsA had no additive effect. The protein kinase A (PKA) blocker RpcAMPs had no effect on the CsA-induced increase in membrane capacitance. Intra- and extracellular application of tacrolimus did not alter membrane capacitance. A calmodulin antagonist (calmidazolium) and CsA, but not tacrolimus, significantly stimulated renin release from cultured juxtaglomerular cells. Juxtaglomerular cells expressed the calcineurin isoforms A-beta and A-gamma but not A-alpha. Plasma renin concentrations (PRCs) were not different in wild-type, calcineurin A-alpha, or A-beta knockout mice but increased after CsA treatment of the A-alpha knockout, while renin mRNA was suppressed. We conclude that calcineurin and calcium/calmodulin suppress exocytosis of renin from juxtaglomerular cells independent of PKA.
authors.affiliation: Department of Physiology and Pharmacology, Institute of Medical Biology, University of Southern Denmark, J.B. Winslowsvej 21, Odense, Denmark. kmadsen@health.sdu.dk
authors.forename: Kirsten
authors.initials: K
authors.lastname: Madsen
authors.forename: Ulla G
authors.initials: UG
authors.lastname: Friis
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Gooch
authors.forename: Pernille B
authors.initials: PB
authors.lastname: Hansen
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Holmgaard
authors.forename: Ole
authors.initials: O
authors.lastname: Skøtt
authors.forename: Boye L
authors.initials: BL
authors.lastname: Jensen
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D002614:Chelating Agents; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D016572:Cyclosporine; D004533:Egtazic Acid; D025802:Electric Capacitance; D005089:Exocytosis; D007166:Immunosuppressive Agents; D007606:Juxtaglomerular Apparatus / Q000378:metabolism*; D008297:Male; D051379:Mice; D018408:Patch-Clamp Techniques; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000097:blood / Q000378:metabolism*; D013449:Sulfonamides
chemical_list: D002147:Calmodulin; D002614:Chelating Agents; D007166:Immunosuppressive Agents; D020033:Protein Isoforms; D012333:RNA, Messenger; D013449:Sulfonamides; D004533:Egtazic Acid; C033772:N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide; D016572:Cyclosporine; D017868:Cyclic AMP-Dependent Protein Kinases; C120817:calcineurin phosphatase; D019703:Calcineurin; D010744:Phosphoric Monoester Hydrolases; D012083:Renin; D002118:Calcium