Defective ryanodine receptor N-terminus inter-subunit interaction is a common mechanism in neuromuscular and cardiac disorders

Abstract

The ryanodine receptor (RyR) is a homotetrameric channel mediating sarcoplasmic reticulum Ca2+ release required for skeletal and cardiac muscle contraction. Mutations in RyR1 and RyR2 lead to life-threatening malignant hyperthermia episodes and ventricular tachycardia, respectively. In this brief report, we use chemical cross-linking to demonstrate that pathogenic RyR1 R163C and RyR2 R169Q mutations reduce N-terminus domain (NTD) tetramerization. Introduction of positively-charged residues (Q168R, M399R) in the NTD-NTD inter-subunit interface normalizes RyR2-R169Q NTD tetramerization. These results indicate that perturbation of NTD-NTD inter-subunit interactions is an underlying molecular mechanism in both RyR1 and RyR2 pathophysiology. Importantly, our data provide proof of concept that stabilization of this critical RyR1/2 structure-function parameter offers clear therapeutic potential.

Cysteines 1078 and 2991 cross-linking plays a critical role in redox regulation of cardiac ryanodine receptor (RyR)

“…To identify hRyR2 cysteine oxidation which promotes cross-linking and ER Ca 2+ leak, we analyzed the channel’s N-terminal region (NTR) structure (residues 1-547), which includes three domains (A, B, and C) 32 . The NTR of RyR2 has been shown to play an important role in the channel’s tetramer formation and regulation of the channel’s function 33 – 36 . It has also been characterized as a “hotspot” for the hRyR2 mutations associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) 37 , 38 , suggesting its important role in channel gating.…”