Dual regulatory effects of PI(4,5)P₂ on TREK-2 K⁺ channel through antagonizing interaction between the alkaline residues (K³³⁰ and R^355-357) in the cytosolic C-terminal helix

Abstract

TWIK-related two-pore domain K + channel-2 (TREK-2) has voltage-independent activity and shows additional activation by acidic intracellular pH (pH i ) via neutralizing the E 332 in the cytoplasmic C terminal (Ct). We reported opposite regulations of TREK-2 by phosphatidylinositol 4,5-bisphosphate (PIP 2 ) via the alkaline K 330 and triple Arg residues (R 355-357 ); inhibition and activation, respectively. The G 334 between them appeared critical because its mutation (G 334 A) endowed hTREK-2 with tonic activity, similar to the mutation of the inhibitory K 330 (K 330 A). To further elucidate the role of putative bent conformation at G 334 , we compared the dual mutation forms, K 330 A/G 334 A and G 334 A/R 355-7 A, showing higher and lower basal activity, respectively. The results suggested that the tonic activity of G 334 A owes to a dominant influence from R 355-7 . Since there are additional triple Arg residues (R 377-9 ) distal to R 355-7 , we also examined the triple mutant (G 334 A/R 355-7 A/R 377-9 A) that showed tonic inhibition same with G 334 A/R 355-7 A. Despite the state of tonic inhibition, the activation by acidic pH i was preserved in both G 334 A/R 355-7 A and G 334 A/R 355-7 A/R 377-9 A, similar to the R 355-7 A. Also, the inhibitory effect of ATP could be commonly demonstrated under the activation by acidic pH i in R 355-7 A, G 334 A/R 355-7 A, and G 334 A/R 355-7 A/R 377-9 A. These results suggest that the putative bent conformation at G 334 is important to set the tug-of-war between K 330 and R 355-7 in the PIP 2 -dependent regulation of TREK-2.

Amelioration of obsessive-compulsive disorder by intracellular acidification of cortical neurons with a proton pump inhibitor

“…The exact mechanisms underlying acidification-induced activity modulation in neurons remain unclear, whereas numerous molecules alter their function in response to intracellular H + in the brain [ 55 ]. Some channels may be partly involved in modulating neural activity through both toxic acidosis and physiological pH reduction, including tandem pore domain weak inward rectifier K + channel-related K + channels (TREKs) [ 56 – 58 ] and high-voltage-activated voltage-dependent Ca 2+ channels [ 59 – 63 ]. These observations suggest that a slight decrease in intracellular pH modulates pyramidal neuron activity in the lateral OFC.…”

Activity of TREK-2-like Channels in the Pyramidal Neurons of Rat Medial Prefrontal Cortex Depends on Cytoplasmic Calcium

“…Exogenous PI(4,5)P2 inhibited the spontaneous increase in TREK currents induced by ATP depletion. ATP inhibition of TREK channels can be mediated by phosphatidylinositol kinase, which increases the amount of PI (4,5)P2 in the plasma membrane, and the increase in PI (4,5)P2 has an inhibitory effect on TREK currents [21,[39][40][41]. This inhibitory effect of PI (4,5)P2 can be relieved by anionic phospholipids, such as phosphatidic acid, which is a TREK agonist.…”