Chlorpromazine inhibits EAG1 channels by altering the interdomain coupling

Area of Science:

• Molecular biology
• Biophysics
• Pharmacology

Background:

• EAG1 potassium channels are crucial drug targets for neurological disorders and cancer.
• These channels assemble as tetramers, with Per-Arnt-Sim (PAS) and cyclic nucleotide-binding homology (CNBH) domains regulating gating.
• Small molecules inhibiting EAG1 channels bind to PAS domains, but their allosteric mechanisms remain unclear.

Purpose of the Study:

• To investigate the allosteric pathways of EAG1 channel regulation by small molecule PAS domain binders.
• To elucidate how chlorpromazine binding to the PAS domain affects channel gating and inter-domain communication.

Main Methods:

• Molecular dynamics (MD) simulations and network analysis.
• Surface plasmon resonance (SPR) assays.
• Mutagenesis coupled electrophysiology.

Main Results:

• MD simulations and network analysis showed chlorpromazine alters PAS-CNBH domain interactions.
• SPR confirmed chlorpromazine's effect on isolated PAS and CNBH domain interactions.
• Network analysis indicated chlorpromazine alters coupling across EAG1 regulatory domains (PAS/CNBH ring, VSD, pore).
• Chlorpromazine binding minimally affected the Cole-Moore shift, suggesting effects on VSD movement occur at more depolarized potentials.

Conclusions:

• Chlorpromazine regulates EAG1 channels by modulating inter-domain communication, primarily affecting PAS-CNBH interactions.
• The study provides insights into the allosteric mechanisms of small molecule inhibitors targeting EAG1 channels.
• Findings contribute to understanding channelopathies and developing novel therapeutics for cancer and neurological conditions.