title: Ca2+/calmodulin kinase II increases ryanodine binding and Ca2+-induced sarcoplasmic reticulum Ca2+ release kinetics during beta-adrenergic stimulation.
abstract: We aimed to define the relative contribution of both PKA and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) cascades to the phosphorylation of RyR2 and the activity of the channel during beta-adrenergic receptor (betaAR) stimulation. Rat hearts were perfused with increasing concentrations of the beta-agonist isoproterenol in the absence and the presence of CaMKII inhibition. CaMKII was inhibited either by preventing the Ca(2+) influx to the cell by low [Ca](o) plus nifedipine or by the specific inhibitor KN-93. We immunodetected RyR2 phosphorylated at Ser2809 (PKA and putative CaMKII site) and at Ser2815 (CaMKII site) and measured [(3)H]-ryanodine binding and fast Ca(2+) release kinetics in sarcoplasmic reticulum (SR) vesicles. SR vesicles were isolated in conditions that preserved the phosphorylation levels achieved in the intact heart and were actively and equally loaded with Ca(2+). Our results demonstrated that Ser2809 and Ser2815 of RyR2 were dose-dependently phosphorylated under betaAR stimulation by PKA and CaMKII, respectively. The isoproterenol-induced increase in the phosphorylation of Ser2815 site was prevented by the PKA inhibitor H-89 and mimicked by forskolin. CaMKII-dependent phosphorylation of RyR2 (but not PKA-dependent phosphorylation) was responsible for the beta-induced increase in the channel activity as indicated by the enhancement of the [(3)H]-ryanodine binding and the velocity of fast SR Ca(2+) release. The present results show for the first time a dose-dependent increase in the phosphorylation of Ser2815 of RyR2 through the PKA-dependent activation of CaMKII and a predominant role of CaMKII-dependent phosphorylation of RyR2, over that of PKA-dependent phosphorylation, on SR-Ca(2+) release during betaAR stimulation.
authors.affiliation: Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina.
authors.forename: Paola
authors.initials: P
authors.lastname: Ferrero
authors.forename: Matilde
authors.initials: M
authors.lastname: Said
authors.forename: Gina
authors.initials: G
authors.lastname: Sánchez
authors.forename: Leticia
authors.initials: L
authors.lastname: Vittone
authors.forename: Carlos
authors.initials: C
authors.lastname: Valverde
authors.forename: Paulina
authors.initials: P
authors.lastname: Donoso
authors.forename: Alicia
authors.initials: A
authors.lastname: Mattiazzi
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mundiña-Weilenmann
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases; D004305:Dose-Response Relationship, Drug; D007545:Isoproterenol / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D000096926:Benzenesulfonamides
chemical_list: D000318:Adrenergic beta-Agonists; D001596:Benzylamines; D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol; D007546:Isoquinolines; D009543:Nifedipine; D017346:Protein Serine-Threonine Kinases; D012433:Ryanodine; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide