Defining the Polycystin Pharmacophore Through HTS & Computational Biophysics

Area of Science:

• Ion channel pharmacology
• Molecular neuropharmacology
• Drug discovery

Background:

• Polycystins (PKD2, PKD2L1) are TRP channels crucial for brain and kidney function, implicated in diseases like polycystic kidney disease and autism spectrum disorder.
• Despite their importance, the polycystin pharmacophore remains undefined due to challenges in drug screening and unique subcellular localization.
• PKD2L1 forms constitutively active plasma membrane channels when overexpressed, making it a target for pharmacological modulation.

Purpose of the Study:

• To identify potent modulators of PKD2L1 ion channels.
• To define the molecular interactions and binding sites of identified modulators.
• To establish a framework for expanding chemical knowledge of polycystins.

Main Methods:

• High-throughput electrophysiology screening of HEK293 cells expressing PKD2L1 F514A.
• In-silico docking analysis and site-directed mutagenesis to identify receptor sites.
• Assessment of binding site accessibility using membrane-impermeable QX-314.

Main Results:

• Identification of potent PKD2L1 antagonists with diverse chemical structures.
• Discovery of similarities between PKD2L1 and voltage-gated sodium channel pharmacology.
• Localization of a novel, open-state accessible lateral fenestration receptor within the PKD2L1 pore.

Conclusions:

• The developed screening approach is effective for polycystin drug discovery.
• A mechanism of inhibition stabilizing the PKD2L1 inactivated state was elucidated.
• Novel receptor moieties were identified for developing specific TRP channel antagonists.