Nanoscale organization in the cell membrane dynamically modulates the biophysics of voltage-gated sodium channels.

Abstract

Precise regulation of ion channel biophysics is an essential life process that governs electrical signaling in excitable tissues. Many ion channels, including voltage-gated Na⁺ channels (Na_Vs), exist in the membrane as clusters, which show distinct biophysical behavior not predicted by single-channel measurements. In both heterologous and native systems, we report that single-channel-based predictions significantly overestimated Na⁺ current (I_Na) amplitudes from multi-channel clusters. Computational modeling suggested that these observations could reflect interactions between adjacent channels, such as those recently reported between Na_Vs, and identified specific biophysical consequences thereof. This updated model not only accurately predicted behaviors observed from Na_V clusters and consequent cellular physiology, but also suggested the possibility that clustered Na_Vs may respond differently to use-dependent pharmacological agents. Experiments validated the latter prediction and further identified modulation of clustering as an approach to correcting macroscopic electrophysiological dysfunction resulting from Na_V defects linked to life-threatening arrhythmias and seizures. Thus, our study not only motivates a fundamental revision of how ion channels behave when clustered but also highlights resulting biophysical effects as important considerations for pharmacology and a potential therapeutic target to address human disease.