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

Authors:

Mikhail Tarasov, Madison Ammon, Jan Otto Wirth, Christopher Hampton, Zoja Selimi, Rengasayee Veeraraghavan, Przemysław B. Radwański

Keywords:

Ion channel; voltage-gated Na+ channels; channel clustering

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 (NaVs), 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 (INa) amplitudes from multi-channel clusters. Computational modeling suggested that these observations could reflect interactions between adjacent channels, such as those recently reported between NaVs, and identified specific biophysical consequences thereof. This updated model not only accurately predicted behaviors observed from NaV clusters and consequent cellular physiology, but also suggested the possibility that clustered NaVs 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 NaV 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.

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