The Nav1.2 channel is regulated by GSK3

Area of Science:

• Neuroscience
• Molecular Biology
• Channelopathies

Background:

• Phosphorylation is crucial for regulating voltage-gated sodium (Na(v)) channels and neuronal excitability.
• Glycogen synthase kinase 3 (GSK3) is implicated in various brain disorders.
• The direct regulation of Na(v) channels by GSK3 remains largely unexplored.

Purpose of the Study:

• To investigate whether glycogen synthase kinase 3 (GSK3) directly phosphorylates and regulates neuronal voltage-gated sodium (Na(v)) channels.
• To elucidate the mechanism by which GSK3 influences Na(v) channel function.

Main Methods:

• Patch-clamp electrophysiology to measure Na(v)1.2 channel currents in HEK-293 cells.
• Quantitative analysis of mRNA and protein expression using RT-PCR and Western blot.
• In vitro phosphorylation assays coupled with mass spectrometry to identify phosphorylation sites.
• Cell surface labeling and confocal microscopy to assess channel localization.

Main Results:

• GSK3 inhibition potentiated Na(v)1.2 peak current density, while GSK3 overexpression suppressed it.
• Neither mRNA nor total protein levels of Na(v)1.2 were affected by GSK3 modulation.
• GSK3 inhibition increased Na(v)1.2 channel surface expression at the plasma membrane.
• GSK3β was identified to directly phosphorylate Na(v)1.2 at threonine residue T(1966) within its C-terminal tail.

Conclusions:

• GSK3 directly modulates Na(v) channel function through phosphorylation of its C-terminal tail.
• This provides a novel mechanism for regulating neuronal excitability.
• Findings offer insights into signaling dysregulation in neuropsychiatric disorders.