Mechanisms Underlying Small Molecule Regulation of K2P Channel Activity for the Treatment of Pain

The selective up-regulation of K2P channel activity by small molecules represents an attractive strategy for the treatment of pain. The student will be part of a major study of how small molecules and other physiologically relevant ligands regulate K2P channel activity.

We have recently determined the crystal structures of two prototypical human K2P channels (TREK1 and TREK2) in different conformations and in complex with a state-dependent inhibitor. This has provided important insights into how K2P channels work, and now presents an exciting experimental framework to address more complex questions about the molecular mechanisms of K2P channel gating and regulation.

We are currently combining some of the most recent advances in membrane protein structural biology (LCP and X-Ray Free Electron Lasers) to identify novel conformations of TREK1 and TREK2 channels and also their structures in complex with a number of (brominated) small molecule binders (both inhibitors and activators).

Based upon this information, the student will be involved in a multidisciplinary approach to:

1) Validate these ligand binding sites via site-directed mutagenesis and functional analysis.
2) Dissect the structural and biophysical mechanisms underlying ligand action.
3) Improve/modulate ligand efficacy through the rational design/synthesis of novel ligands.
4) Examine the selectivity of novel ligands amongst different K2P channels, and test their efficacy in model cellular systems (e.g. cultured rat DRG and/or human stem cell-derived sensory neurons).

These aims will involve electrophysiological analysis of heterologously expressed WT and mutant channels. This will allow us to probe how ligand binding affects channel gating and regulation, and how different activators influence inhibition by state-dependent blockers. Current results have identified structurally distinct open states and the proposed studies will allow us to correlate these different states with mechanisms of drug action. We will also exploit our collaborations with industry to improve ligand efficacy through the rational design and synthesis of novel ligands and high throughput-screening of ligand libraries.

Ligand efficacy and selectivity will also be examined by studying their effects on different cloned K2P channels (e.g. TREK/TRAAK/TRESK), as well as on native K2P channel currents in model cell types e.g. DRG and hES neurons where the principal K2P channels are thought to be TREK2 and TRESK.

With regards to potential risks involved, we believe they are mitigated by the fact this project forms part of a larger established and successful research programme, and because we have extensive published and preliminary evidence demonstrating the feasibility of the proposed methods.