A Novel Ryanodine Receptor Mutation Linked to Sudden Death Increases Sensitivity to Cytosolic Calcium

• DOI: 10.1161/circresaha.111.244970
• Publication Date: 2011-06-10T09:07:57Z
• Authors: Albano C. Meli; Marwan M. Refaat; Miroslav Dura; Steven Reiken; Anetta Wronska; Julianne Wojciak; Joan Carroll; Melvin M. Scheinman; Andrew R. Marks
• Keywords: Male; 0301 basic medicine; 0303 health sciences; Ryanodine Receptor Calcium Release Channel; Middle Aged; Cyclic AMP-Dependent Protein Kinases; Recombinant Proteins; 3. Good health; Tacrolimus Binding Proteins; Electrocardiography; 03 medical and health sciences; Catecholamines; Cytosol; Death, Sudden, Cardiac; HEK293 Cells; Phenotype; Diastole; Mutagenesis, Site-Directed; Tachycardia, Ventricular; Humans; Point Mutation; Calcium; Ion Channel Gating

Rationale: Mutations in the cardiac type 2 ryanodine receptor (RyR2) have been linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT-associated RyR2 mutations cause fatal arrhythmias young individuals during β-adrenergic stimulation. Objective: This study sought determine effects of a novel RyR2-G230C mutation and whether this RyR2-P2328S alter sensitivity channel luminal calcium (Ca 2+ ). Methods Results: Functional characterizations recombinant human channels were performed under conditions mimicking stress. Human mutant generated by site-directed mutagenesis heterologously expressed HEK293 cells together with calstabin2. measured examine regulation cytosolic versus sarcoplasmic reticulum Ca . A 50-year-old white man repeated syncopal episodes after exercise had arrest harbored RyR2-G230C. cAMP-dependent protein kinase–phosphorylated exhibited significantly higher open probability at diastolic concentrations, associated depletion The sensitivities WT-like. Conclusions: exhibits similar biophysical defects compared previously characterized CPVT mutations: decreased binding stabilizing subunit calstabin2 leftward shift dependence for activation that simulate exercise, consistent “leaky” channel. Both exhibit normal activation. Thus, leak caused reduced levels is common mechanism underlying CPVT.