Phospholamban ablation rescues the enhanced propensity to arrhythmias of mice with CaMKII-constitutive phosphorylation of RyR2-S2814 site

MAZZOCCHI G; SOMMESE L; PALOMEQUE J; FELICE J; DI CARLO MN; FAINSTEIN D; GONZALEZ P; CONTRERAS P; SKAPURA D; MCCAULEY MD; LASCANO EC; NEGRONI JA; KRANIAS EG; WEHRENS XH; VALVERDE CA; MATTIAZZI A

THE JOURNAL OF PHYSIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 594 p. 3005 - 3010

0022-3751

Background:Mice withconstitutive pseudo-phosphorylation at Ser2814-RyR2 (S2814D+/+), increasethe propensity to arrhythmias under β-adrenergic stress conditions. Althoughabnormal Ca2+ release from the SR has been linked to arrhythmogenesis, the role playedby SR Ca2+ uptakeremains controversial. We tested the hypothesis that an increase in SR Ca2+ uptake is able to rescue the increased arrhythmiapropensity of S2814D+/+ mice. Methodsand Results: Wegenerated PLN-deficient/S2814D+/+ knock-in mice by crossing the twocolonies (SD+/+/KO mice). SD+/+/KOmyocytes exhibited both, increased SR Ca2+ uptake seen in PLNKO myocytesand diminished SR Ca2+ load (relative to PLNKO), characteristic ofS2814D+/+ myocytes. Ventricular arrhythmias evoked bycatecholaminergic challenge (caffeine/epinephrine) in S2814D+/+ mice in vivo orprogrammed electric stimulation and high extracellular Ca2+ inS2814D+/- hearts ex vivo, were significantly diminished by PLN ablation. At the myocyte level, PLNablation converted the arrhythmogenic Ca2+ waves evoked by high extracellular Ca2+ provocation in S2814D+/+ mice intonon-propagated Ca2+ mini-waveson confocal microscopy. Myocyte Ca2+ waves, typical of S2814D+/+ mice, could be evoked in SD+/+/KOcells by partially inhibiting SERCA2a. A mathematical human myocyte modelreplicated these results and allowed for predicting the increase in SR Ca2+ uptake required to prevent the arrhythmias inducedby a CaMKII-dependentleaky RyR2. Conclusions: Ourresults demonstrate that increasing SR Ca2+ uptake byPLN ablation can prevent the arrhythmic events triggered by SR Ca2+ leak dueto CaMKII-dependent phosphorylation of RyR2-S2814 site and underscore thebenefits of increasing SERCA2a activity on SR Ca2+ triggeredarrhythmias.