Structural and Functional Regulation of RyR2 in Cardiac Calcium Handling and Arrhythmogenesis

Area of Science:

• Cardiology
• Molecular Biology
• Structural Biology

Background:

• Cardiac calcium handling is vital for excitation-contraction coupling (ECC).
• Ryanodine receptor type 2 (RyR2) is the primary sarcoplasmic reticulum Ca2+ release channel in cardiomyocytes.
• RyR2 dysfunction is implicated in cardiac arrhythmias like heart failure (HF) and catecholaminergic polymorphic ventricular tachycardia (CPVT).

Purpose of the Study:

• To review the structural basis of RyR2.
• To elucidate RyR2's role in cardiac ECC and Ca2+ homeostasis.
• To detail the regulatory mechanisms of RyR2 activity by key modulators and disease-associated mutations.

Main Methods:

• Integration of high-resolution cryo-electron microscopy (cryo-EM) data.
• Analysis of molecular and cellular studies on RyR2 regulation.
• Review of clinical evidence linking RyR2 mutations to arrhythmogenic heart diseases.

Main Results:

• Cryo-EM has revealed RyR2's gating mechanisms, ligand-binding sites, and structural features.
• RyR2 mediates calcium-induced calcium release (CICR) and maintains Ca2+ homeostasis with SERCA2a and NCX.
• Modulators and mutations affect RyR2 activity, leading to store-overload-induced Ca2+ release (SOICR) and arrhythmias; ROS can exacerbate this through oxidation.

Conclusions:

• RyR2 is a critical sensor of myocardial function, with its structure and regulation now better understood.
• Further research into the effects of RyR2 mutations is needed.
• Deeper mechanistic insights into RyR2 are essential for developing novel therapies for RyR2-related cardiac diseases.