TRESK (K2P18.1) Background Potassium Channel Is Activated by Novel-Type Protein Kinase C via Dephosphorylation

Abstract

TRESK (K2P18.1) background K 1 channel is a major determinant of the excitability of primary sensory neurons. It has been reported that human TRESK is activated by the protein kinase C (PKC) activator PMA (phorbol 12-myristate 13-acetate) in Xenopus oocytes. In the present study, we investigated the mechanism of this PKC-dependent TRESK regulation. We show that TRESK is activated by coexpression of the novel-type PKC isoforms h and «. The effect of PKC is not mediated by calcineurin phosphatase, which is known to evoke the calciumdependent TRESK activation. Mutations of the calcineurinbinding sites in the channel (PQAAAS-AQAP) did not influence the PMA-induced increase of potassium current. In sharp contrast, the mutations of the target residue of calcineurin in TRESK, S264A, and S264E prevented the effect of PMA. The enforced phosphorylation of S264 by coexpression of a microtubule-affinity regulating kinase construct (MARK2D) also abolished the PKC-dependent TRESK activation. These results suggest that, in addition to calcineurin, PKC regulates TRESK by changing the phosphorylation status of S264. Coexpression of PKC slowed recovery of the K 1 current to the resting state after the calcineurin-dependent dephosphorylation of TRESK. Therefore, the likely mechanism of action is the PKC-dependent inhibition of the kinase responsible for the (re)phosphorylation of the channel at S264. The PKC-dependent dephosphorylation of TRESK protein was also detected by the Phos-tag SDS-PAGE method. In summary, the activation of novel-type PKC results in the slow (indirect) dephosphorylation of TRESK at the regulatory residue S264 in a calcineurin-independent manner.

Altered functional properties of a missense variant in the TRESK K+ channel (KCNK18) associated with migraine and intellectual disability

“…TRESK channels are expressed in a number of neuronal populations in different regions of the central and peripheral nervous systems in addition to the spinal cord and dorsal root ganglia [16,17,19] and can be regulated by Gαq-signaling pathways [4,8,20]. This strongly suggests that TRESK may contribute broadly to the maintenance and regulation of the resting membrane potential in these cell types; channel dysfunction during development of the CNS may therefore also need to be considered because K + -dependent alterations of neuronal membrane potential and excitability are known to cause serious neurodevelopment disorders with intellectual disability (9).…”

TRESK channel contributes to depolarization-induced shunting inhibition and modulates epileptic seizures

“…To uncover the relevant channels responsible for the effects of sustained depolarization, we performed experiments in the presence of genistein (non-specific K + channel blocker) that is able to block some K2P channels other than TRESK (Gierten et al, 2008;Zhao et al, 2008), or PMA (protein kinase C [PKC] activator) that blocks TREK-1 and TREK-2 (Enyedi and Czirjá k, 2010) and modestly inhibits TASK channels (Mathie, 2007). Although PMA activates human TRESK, it has little effect on mouse TRESK (Pergel et al, 2019). We found that both genistein and PMA failed to block depolarization-induced suppression of GABAergic responses (Figures S2A-S2D), suggesting that TRESK is a putative channel candidate.…”

The Background K+ Channel TRESK in Sensory Physiology and Pain

“…In any case, the effect was independent of direct PKC-mediated phosphorilation of the channel since mutation of putative PKC phosphorilation sites did not abolish the PMA effect [ 53 ]. Confirmation of this effect was later reported and the likely mechanism of action involves the nPKC-dependent inhibition of the kinase responsible for the rephosphorylation of the channel at S264 [ 54 ].…”

“…In any case, the effect was independent of direct PKC-mediated phosphorilation of the channel since mutation of putative PKC phosphorilation sites did not abolish the PMA effect [53]. Confirmation of this effect was later reported and the likely mechanism of action involves the nPKC-dependent inhibition of the kinase responsible for the rephosphorylation of the channel at S264 [54]. It has been proposed that calcineurin-inhibitor pain syndrome (CIPS) that occurs as a result of the phosphatase activity inhibition by immunosuppressive drugs, such as tacrolimus (FK506) or cyclosporin A, could be due to impaired modulation of TRESK current.…”