Distinct modulation of inactivation by a residue in the pore domain of voltage-gated Na+ channels: mechanistic insights from recent crystal structures

Abstract

Inactivation of voltage-gated Na+ channels (VGSC) is essential for the regulation of cellular excitability. The molecular rearrangement underlying inactivation is thought to involve the intracellular linker between domains III and IV serving as inactivation lid, the receptor for the lid (domain III S4-S5 linker) and the pore-lining S6 segements. To better understand the role of the domain IV S6 segment in inactivation we performed a cysteine scanning mutagenesis of this region in rNav 1.4 channels and screened the constructs for perturbations in the voltage-dependence of steady state inactivation. This screen was performed in the background of wild-type channels and in channels carrying the mutation K1237E, which profoundly alters both permeation and gating-properties. Of all tested constructs the mutation I1581C was unique in that the mutation-induced gating changes were strongly influenced by the mutational background. This suggests that I1581 is involved in specific short-range interactions during inactivation. In recently published crystal structures VGSCs the respective amino acids homologous to I1581 appear to control a bend of the S6 segment which is critical to the gating process. Furthermore, I1581 may be involved in the transmission of the movement of the DIII voltage-sensor to the domain IV S6 segment.

Pharmacological and nutritional targeting of voltage-gated sodium channels in the treatment of cancers

“…Therefore, early effort for the discovery of Na V a blockers mainly relied on strategies such as ligand-based drug design, natural-product-based drug design, in silico screening, and similarity searches. However, recent reports on the structures of human and bacterial Na V a and bound ligands shed light on their binding site (Cervenka et al, 2018;Nguyen et al, 2019;Pan et al, 2018;Payandeh et al, 2011;Shen et al, 2017Shen et al, , 2018Shen et al, , 2019. These reports will certainly aid in the structurebased design and discovery of Na V a blockers.…”

Inactivated voltage-gated sodium channels are preferentially targeted in cinacalcet block of mouse neocortical action potentials

“…Models that describe complex VGSC function indicate the channels can occupy multiple fast and slow inactivation states (Ulbricht, 2005; Milescu et al ., 2010; Goldfarb, 2012; Cervenka et al ., 2018). The indirect mechanism of block by cinacalcet adds further complexity.…”

“…The copyright holder for this preprint this version posted August 15, 2022. ; https://doi.org/10.1101/2022.08.15.504002 doi: bioRxiv preprint 2012; Cervenka et al, 2018).The indirect mechanism of block by cinacalcet adds further complexity. To reduce the number of parameters we described the action of cinacalcet using a simpler model with only single fast and slow inactivation states.…”

“…Models that describe complex VGSC function indicate the channels can occupy multiple fast and slow inactivation states (Ulbricht, 2005;Milescu et al, 2010;Goldfarb, 2012;Cervenka et al, 2018).The indirect mechanism of block by cinacalcet adds further complexity. To reduce the number of parameters we described the action of cinacalcet using a simpler model with only single fast and slow inactivation states.…”

Variable patterns of mutation density among NaV1.1, NaV1.2 and NaV1.6 point to channel-specific functional differences associated with childhood epilepsy

“…Mutations in this region have been shown to effect channel function in the muscle-expressed channel Na V 1.4 [33]. In DIII the S4-S5 linker is hypothesized to interact with amino acids in S6 DIV that transmit movement of S4 DIII to S6 DIV and plays a role in fast inactivation [34]. While the S4-S5 DIV linker was found to interact with the inactivation gate during fast inactivation and mutations in this region were found to disrupt fast inactivation [35].…”