Block of TREK and TRESK K2P channels by lamotrigine and two derivatives sipatrigine and CEN-092

Yvonne Walsh,Michael Leach,Emma L Veale,Alistair Mathie

doi:10.1016/j.bbrep.2021.101021

Abstract

TREK and TRESK K2P channels are widely expressed in the nervous system, particularly in sensory neurons, where they regulate neuronal excitability. In this study, using whole-cell patch-clamp electrophysiology, we characterise the inhibitory effect of the anticonvulsant lamotrigine and two derivatives, sipatrigine and 3,5-diamino-6-(3,5-bistrifluoromethylphenyl)-1,2,4-triazine (CEN-092) on these channels.Sipatrigine was found to be a more effective inhibitor than lamotrigine of TREK-1, TREK-2 and TRESK channels. Sipatrigine was slightly more potent on TREK-1 channels (EC50 = 16 μM) than TRESK (EC50 = 34 μM) whereas lamotrigine was equally effective on TREK-1 and TRESK. Sipatrigine was less effective on a short isoform of TREK-2, suggesting the N terminus of the channel is important for both inhibition and subsequent over-recovery. Inhibition of TREK-1 and TREK-2 channels by sipatrigine was reduced by mutation of a leucine residue associated with the norfluoxetine binding site on these channels (L289A and L320A on TREK-1 and TREK-2, respectively) but these did not affect inhibition by lamotrigine. Inhibition of TRESK by sipatrigine and lamotrigine was attenuated by mutation of bulky phenylalanine residues (F145A and F352A) in the inner pore helix. However, phosphorylation mutations did not alter the effect of sipatrigine. CEN-092 was a more effective inhibitor of TRESK channels than TREK-1 channels.It is concluded that lamotrigine, sipatrigine and CEN-092 are all inhibitors of TREK and TRESK channels but do not greatly discriminate between them. The actions of these compounds may contribute to their current and potential use in the treatment of pain and depression.

Highlights

Pulmonary arterial hypertension (PAH) is a progressive vascular remodeling disease which eventually leads to right ventricular heart failure and premature death (Simonneau et al, 2019)
We first investigated whether TREK-1 and TREK-2 channel current was directly affected by PGI2 stable analogue, treprostinil
Where at a concentration of 1 μM, the averaged TREK-2 current of 39.9 pA pF−1 in control solution was reduced to 18.7 pA pF−1 in the presence of treprostinil (Figures 1E,F)

Summary

Introduction

Pulmonary arterial hypertension (PAH) is a progressive vascular remodeling disease which eventually leads to right ventricular heart failure and premature death (Simonneau et al, 2019). Given PGI2 is a key vasoactive regulator released by endothelial cells in the pulmonary arteries, initial, therapeutic management of PAH involved giving epoprostenol (synthetic PGI2), but due to its short chemical and biological half-life led to the development of PGI2 stable analogues, iloprost, beraprost and treprostinil or more recently the non-prostanoid PGI2 receptor agonist, selexipag. These therapies improve exercise capacity, breathing, hemodynamic circulation, and patient survival in various trials (Gomberg-Maitland and Olschewski, 2008; Sitbon and Vonk Noordegraaf, 2017)

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