Lipid regulation of hERG1 channel function

Area of Science:

• Biophysics
• Molecular Biology
• Cardiology

Background:

• Lipid regulation is crucial for ion channel function and electrical signaling.
• Understanding how specific lipids affect ion channel gating is essential for cell physiology.

Purpose of the Study:

• To investigate the mechanistic effects of lipophilic molecules, specifically a ceramide-sphingolipid probe, on the gating kinetics and potassium (K+) currents of the hERG1 channel.
• To elucidate the binding sites and allosteric modulation mechanisms of ceramide on hERG1.

Main Methods:

• Utilized microsecond-long molecular dynamics (MD) simulations.
• Performed experimental mutagenesis and electrophysiology.
• Combined simulation and experimental data for comprehensive analysis.

Main Results:

• The sphingolipid probe induced a left shift in activation voltage and faster deactivation rates.
• Ceramide binding was identified at the interface of the pore and voltage-sensing domains in a unique channel crevice.
• Observed current blockade comparable to traditional hERG1 blockers.

Conclusions:

• Ceramide allosterically modulates hERG1 channel activity through a conformational selection mechanism.
• The findings provide mechanistic insights into lipid regulation of ion channel function.
• This study highlights a novel interaction site for lipophilic modulation in mammalian channels.