Mutation-linked defective inter-domain interactions within ryanodine receptor as a pathogenic mechanism of catecholaminergic polymorphic ventricular tachycardia

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disease characterized by stress- or exercise- induced ventricular tachycardia, frequently leading to sudden cardiac death. A considerable body of evidence accumulated over recent years suggests that mutation-linked cardiac ryanodine receptor (RyR2) defects cause Ca^2+ leak from sarcoplasmic reticulum, which triggers delayed afterdepolarization and leads to CPVT. However, the underlying mechanism, by which a single mutation in such a large molecule causes drastic effects on the channel function, remains elusive. Here we report that introduction of a human CPVT mutation S2246L into the mouse RyR2 induces aberrant activation of channel gating by forming abnormally tight domain-domain interaction between the S2246L mutable domain and the K201-binding domain. This produces more global conformational change in the RyR2: namely, an aberrant domain unzipping between the N-terminal (a.a. 1–600) domain and the central (a.a. 2000–2500) domain owing to the allosteric conformational coupling mechanism. Pharmacological correction of the defective inter-domain interactions can stop the aberrant Ca^2+ release and lethal arrhythmia. These results provide a new pathogenic mechanism of CPVT and a novel therapeutic strategy against CPVT