title: β1- and β3- voltage-gated sodium channel subunits modulate cell surface expression and glycosylation of Nav1.7 in HEK293 cells.
abstract: Voltage-gated sodium channels (Navs) are glycoproteins composed of a pore-forming α-subunit and associated β-subunits that regulate Nav α-subunit plasma membrane density and biophysical properties. Glycosylation of the Nav α-subunit also directly affects Navs gating. β-subunits and glycosylation thus comodulate Nav α-subunit gating. We hypothesized that β-subunits could directly influence α-subunit glycosylation. Whole-cell patch clamp of HEK293 cells revealed that both β1- and β3-subunits coexpression shifted V ½ of steady-state activation and inactivation and increased Nav1.7-mediated I Na density. Biotinylation of cell surface proteins, combined with the use of deglycosydases, confirmed that Nav1.7 α-subunits exist in multiple glycosylated states. The α-subunit intracellular fraction was found in a core-glycosylated state, migrating at ~250 kDa. At the plasma membrane, in addition to the core-glycosylated form, a fully glycosylated form of Nav1.7 (~280 kDa) was observed. This higher band shifted to an intermediate band (~260 kDa) when β1-subunits were coexpressed, suggesting that the β1-subunit promotes an alternative glycosylated form of Nav1.7. Furthermore, the β1-subunit increased the expression of this alternative glycosylated form and the β3-subunit increased the expression of the core-glycosylated form of Nav1.7. This study describes a novel role for β1- and β3-subunits in the modulation of Nav1.7 α-subunit glycosylation and cell surface expression.
authors.affiliation: Pain Center, Department of Anesthesiology, University Hospital Center and University of Lausanne Lausanne, Switzerland ; Department of Clinical Research, University of Bern Bern, Switzerland.
authors.forename: Cédric J
authors.initials: CJ
authors.lastname: Laedermann
authors.forename: Ninda
authors.initials: N
authors.lastname: Syam
authors.forename: Marie
authors.initials: M
authors.lastname: Pertin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Decosterd
authors.forename: Hugues
authors.initials: H
authors.lastname: Abriel
keywords: Navs β-subunits; biophysical properties; glycosylation; trafficking; voltage-gated sodium channels (Navs)