Pharmacological modulation of voltage-gated ion channels by small molecules

Abstract

Voltage-Gated Ion Channels (VGIC) are transmembrane proteins that form pathways for ions to cross the plasma membrane controlled by the cellular membrane potential. They are at the core of many physiological, pathophysiological and pharmacological processes involved in electrical signaling such as neurotransmission, muscle contraction and hormone secretion. Malfunctioning or changes in the expression levels of these proteins results in a variety of disorders named channelopathies. Thus, VGICs serve as targets for a broad array of pharmacological interventions, including small molecules, gene therapies and antisense oligonucleotides. In my research, I worked with small molecules targeting voltage-gated ion channels, developed by our pharmaceutical chemist collaborators at the University of Ljubljana in Slovenia. We aimed for their in-depth biophysical characterization and to unveil their mechanisms of action for research applications and potentially for future therapeutic use. We first searched for a novel inhibitor targeting specifically the voltage-gated proton channel, HV1. By using the open structure of the channel, our collaborators performed virtual screening and identified hit molecules that we tested experimentally in our system. The most potent compound was fully characterized in detail to understand its biophysical parameters and mechanism of action by using standard patch clamp methods. We further found that the compound also inhibited other off-target channels at higher concentrations. However, when tested at lower concentrations, the compound unveiled an interesting mechanism of action that was further characterized on NaV1.5 KV1.3 channels, which have some similar but also some distinct gating properties. By using a variety of voltage protocols and patch clamping configurations, the molecule named NZ-58 was biophysically characterized and its interaction mechanism with the VSDs of the voltage gated ion channel was unveiled.