A bifunctional actuator to correct loss-of-function deficits in cardiac voltage-gated sodium channels.

Despite their emerging prominence, ion channelopathies have remained challenging to correct, as ion channel dysfunction linked to disease is multifaceted, involving changes in activity and/or localization. Yet, current corrective strategies typically focus on restoring only one aspect leading to incomplete efficacy. Here, focusing on the voltage-gated sodium channel, NaV1.5, whose dysfunction is linked to life-threatening cardiac arrhythmias, we develop a genetically encoded bifunctional actuator as a proof-of-concept molecular strategy to reverse pathophysiological changes in channel function. Specifically, we engineer a high affinity nanobody targeting NaV1.5 with two moieties: (i) a peptide that restores proper inactivation and (ii) a linkage-specific deubiquitinase that promotes surface-membrane localization. Functional validation in heterologous systems and in human and mouse cardiomyocytes demonstrated restoration of NaV1.5 trafficking and/or gating. In all, this approach shows promise for reversing molecular deficits observed with NaV channelopathies and provides a framework to engineer multifunctional modulators targeting ion channelopathies.