Abstract 20480: Channel Pore Mutation of RyR2 Cause Calcium Leak Independent of FKBP12.6-RyR2 and Calmodulin-RyR2 Affinity in R4496C/+ Knock-in Mouse

Introduction and Hypothesis: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited stress-induced arrhythmogenic disease caused by mutations in cardiac ryanodine receptor (RyR2). These mutations cluster in 3 regions of the RyR2 mutable regions (N-terminal, central, and channel pore). Diastolic calcium (Ca) leak via RyR2 can cause lethal arrhythmia such as CPVT. We have reported conformational unzipping within RyR2 reduces calmodulin (CaM)-RyR2 affinity in a central CPVT mouse (R2474S/+). To further understand the pathophysiology of RyR2 mutation on CaM-RyR2 affinity in 3 distinct (N-terminal, central, and channel pore) CPVT knock-in (KI) mice. We tested the hypothesis that RyR2 mutation cause Ca leak by reduced CaM affinity in 3 distinct CPVT KI mice (R176Q/+, R2474S/+, and R4496C/+). Methods and results: Ventricular myocytes was isolated from hearts of 3 KI and wild-type (WT) mice. Fluorescence resonance energy transfer (FRET) between donor-F-FKBP (FK506-binding protein) and accept...