Phospholamban ablation rescues the enhanced propensity to arrhythmias of mice with CaMKII-constitutive phosphorylation of RyR2

MAZZOCCHI, GABRIELA; SOMMESE, LEANDRO MATÍAS; PALOMEQUE, JULIETA; FELICE, JUAN IGNACIO; DI CARLO, MARIANO NAHUEL; FAINSTEIN, DIEGO GERMÁN; GONZÁLEZ, PATRICK; CONTRERAS, PAOLA; SKAPURA, DARLENE G; MCCAULEY, MARK DONALD; LASCANO, ELENA CATALINA; NEGRONI, JORGE ANTONIO; KRANIAS, EVANGELINA GALANI; WEHRENS, XANDER HT T; VALVERDE, CARLOS ALFREDO; MATTIAZZI, RAMONA ALICIA

THE JOURNAL OF PHYSIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 594 p. 3005 - 3030

0022-3751

Mice withconstitutive pseudo-phosphorylation at Ser2814-RyR2 (S2814D+/+) haveincreased propensity to arrhythmias under β-adrenergic stress conditions. Althoughabnormal Ca2+ release from the sarcoplasmic reticulum (SR) has beenlinked to arrhythmogenesis, the role played by SR Ca2+ uptakeremains controversial. We tested the hypothesis that an increase in SR Ca2+uptake is able to rescue the increased arrhythmia propensity of S2814D+/+mice. We generated phospholamban (PLN)-deficient/S2814D+/+ knock-inmice by crossing two colonies, S2814D+/+ and PLNKO mice (SD+/+/KO).SD+/+/KO myocytes exhibited both increased SR Ca2+ uptakeseen in PLN knock-out (PLNKO) myocytes and diminished SR Ca2+ load(relative to PLNKO), a characteristic of S2814D+/+ myocytes.Ventricular arrhythmias evoked by catecholaminergic challenge(caffeine/adrenaline) in S2814D+/+ mice invivo or programmed electric stimulation and high extracellular Ca2+in S2814D+/− hearts ex vivo weresignificantly diminished by PLN ablation. At the myocyte level, PLN ablationconverted the arrhythmogenic Ca2+ waves evoked by high extracellularCa2+ provocation in S2814D+/+ mice into non-propagated Ca2+mini-waves on confocal microscopy. Myocyte Ca2+ waves, typical ofS2814D+/+ mice, could be evoked in SD+/+/KO cells bypartially inhibiting SERCA2a. A mathematical human myocyte model replicatedthese results and allowed for predicting the increase in SR Ca2+uptake required to prevent the arrhythmias induced by a Ca2+?calmodulin-dependentprotein kinase (CaMKII)-dependent leaky RyR2. Our results demonstrate thatincreasing SR Ca2+ uptake by PLN ablation can prevent the arrhythmicevents triggered by SR Ca2+ leak due to CaMKII-dependentphosphorylation of the RyR2-S2814 site and underscore the benefits ofincreasing SERCA2a activity on SR Ca2+-triggered arrhythmias.