Disruption of asparagine-linked glycosylation to rescue and alter gating of the Na V 1.5-Na + channel

AbstractSCN5A gene encodes the voltage-gated sodium channel NaV1.5 which is composed of a pore-forming α subunit of the channel. Asparagine (N)-linked glycosylation is one of the common post-translational modifications in proteins. The aim of this study was to investigate impact of N-linked glycosylation disruption on the Na+ channel, and the mechanism by which glycosylation regulates the current density and gating properties of the Na+ channel. The NaV1.5-Na+ channel isoform ( α submit) derived from human was stably expressed in human embryonic kidney (HEK)-293 cells (Nav1.5-HEK cell). We applied the whole-cell patch-clamp technique to study the impact of N-linked glycosylation disruption in Nav1.5-HEK cell. Inhibition of the N-glycosylation with tunicamycin caused a sig nificant increase of NaV1.5 channel current (INa) when applied for 24  h. Tunicamycin shifted the steady-state inactivation curve to the hyperpolarization direction, whereas the activation curve was unaffected. Recovery from inactivation was prolonged, while the fast phase (τfast) and the slow phase ( τslow) of the current decay was unaffected by tunicamycin.INa was unaffected by tunicamycin in the present of a proteasome inhibitor MG132 [N-[(phenylmethoxy)carbonyl]-l-leucy-N-[(1S)-1-formyl-3-methylbutyl]-l-leucinamide], while it was significantly increased by tunicamycin in the presence of a lysosome inhibitor butyl methacrylate (BMA). These findings suggest that N-glycosylation disruption rescues the ...
Source: Heart and Vessels - Category: Cardiology Source Type: research