Regulation of Kv1.2 Redox-Sensitive Gating by the Transmembrane Lectin LMAN2

Area of Science:

• Neuroscience
• Molecular Biology
• Biophysics

Background:

• Voltage-gated potassium (Kv)1.2 channels are crucial for neural excitability and action potential propagation.
• Kv1.2 channels display significant variability in voltage-dependent gating, unlike related Kv1 channels.
• Extracellular redox potential is a known modulator of Kv1.2 gating variability.

Purpose of the Study:

• To identify extrinsic factors regulating Kv1.2 channel gating.
• To investigate the role of candidate regulatory proteins in Kv1.2 channel function.
• To elucidate the mechanism underlying redox-dependent modulation of Kv1.2 channels.

Main Methods:

• Functional screening of 52 candidate genes using patch clamp electrophysiology.
• Co-expression and knockdown (shRNA) studies of LMAN2 with Kv1.2 channels in cell lines.
• Site-directed mutagenesis to identify critical residues for LMAN2 and redox sensitivity.

Main Results:

• Co-expression of LMAN2 with Kv1.2 channels caused a depolarized shift in activation and slowed kinetics.
• LMAN2 overexpression mimicked extracellular reducing conditions, promoting a slow gating mode.
• Knockdown of LMAN2 reduced Kv1.2 redox sensitivity and gating variability.
• Mutations at F251/T252 in the S2-S3 linker abolished LMAN2 and redox sensitivity.

Conclusions:

• LMAN2 is identified as a regulatory protein influencing the redox-dependent modulation of Kv1.2 channels.
• LMAN2 and extracellular redox potential likely act through a shared regulatory pathway.
• Specific residues (F251, T252) in the Kv1.2 S2-S3 linker are critical for LMAN2 and redox sensitivity.