PIP2 Mediated Inhibition of TREK Potassium Currents by Bradykinin in Mouse Sympathetic Neurons

Abstract

Bradykinin (BK), a hormone inducing pain and inflammation, is known to inhibit potassium M-currents (IM) and to increase the excitability of the superior cervical ganglion (SCG) neurons by activating the Ca2+-calmodulin pathway. M-current is also reduced by muscarinic agonists through the depletion of membrane phosphatidylinositol 4,5-biphosphate (PIP2). Similarly, the activation of muscarinic receptors inhibits the current through two-pore domain potassium channels (K2P) of the “Tandem of pore-domains in a Weakly Inward rectifying K+ channel (TWIK)-related channels” (TREK) subfamily by reducing PIP2 in mouse SCG neurons (mSCG). The aim of this work was to test and characterize the modulation of TREK channels by bradykinin. We used the perforated-patch technique to investigate riluzole (RIL) activated currents in voltage- and current-clamp experiments. RIL is a drug used in the palliative treatment of amyotrophic lateral sclerosis and, in addition to blocking voltage-dependent sodium channels, it also selectively activates the K2P channels of the TREK subfamily. A cell-attached patch-clamp was also used to investigate TREK-2 single channel currents. We report here that BK reduces spike frequency adaptation (SFA), inhibits the riluzole-activated current (IRIL), which flows mainly through TREK-2 channels, by about 45%, and reduces the open probability of identified single TREK-2 channels in cultured mSCG cells. The effect of BK on IRIL was precluded by the bradykinin receptor (B2R) antagonist HOE-140 (d-Arg-[Hyp3, Thi5, d-Tic7, Oic8]BK) but also by diC8PIP2 which prevents PIP2 depletion when phospholipase C (PLC) is activated. On the contrary, antagonizing inositol triphosphate receptors (IP3R) using 2-aminoethoxydiphenylborane (2-APB) or inhibiting protein kinase C (PKC) with bisindolylmaleimide did not affect the inhibition of IRIL by BK. In conclusion, bradykinin inhibits TREK-2 channels through the activation of B2Rs resulting in PIP2 depletion, much like we have demonstrated for muscarinic agonists. This mechanism implies that TREK channels must be relevant for the capture of information about pain and visceral inflammation.

Loss of Cervical Sympathetic Chain Input to the Superior Cervical Ganglia Affects the Ventilatory Responses to Hypoxic Challenge in Freely-Moving C57BL6 Mice

“…Wild-type and genetically-engineered mice are widely used to understand the mechanisms by which hypoxic challenges elicit carotid body-dependent and -independent ventilatory responses (He et al, 2000(He et al, , 2002(He et al, , 2003Kline and Prabhakar, 2000;Pérez-García et al, 2004;Kline et al, 2005;Pichard et al, 2015;Gao et al, 2017;Wang et al, 2017;Ortega-Sáenz et al, 2018;Peng et al, 2018;Prabhakar et al, 2018). The morphology, neurophysiology and neuropharmacology of the mouse CSC-SCG has received considerable investigation over the years (Black et al, 1972;Yokota and Yamauchi, 1974;Banks and Walter, 1975;Inoue, 1975;Lewis and Burton, 1977;Forehand, 1985;Kidd and Heath, 1988;Gibbins, 1991;Kasa et al, 1991;Little and Heath, 1994;Jobling and Gibbins, 1999;El-Fadaly and Kummer, 2003;David et al, 2010;Cadaveira-Mosquera et al, 2012;Pashai et al, 2012;Alberola-Die et al, 2013;Liu and Bean, 2014;Martinez-Pinna et al, 2018;Mitsuoka et al, 2018;Feldman-Goriachnik and Hanani, 2019;Simeone et al, 2019;Rivas-Ramírez et al, 2020). Mouse tissues that receive post-ganglionic projections from the SCG have also been heavily investigated (Krieger et al, 1976;García et al, 1988;…”

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

“…The PLC activator diminishes the PI(4,5)P2 pool [ 46 ] and increases the cytoplasmic Ca 2+ concentration, but the Ca 2+ increase was insufficient to maintain the channel activity. TREK-2 channels are dependent on PI(4,5)P2; we therefore focused on the mechanism of TREK-2-like channel activation based on its interaction with PI(4,5)P2 [ 29 , 32 , 33 , 40 ]. In particular, we considered possible mechanisms involving both Ca 2+ and PI(4,5)P2.…”

“…TREK channels are downregulated by the activation of G-coupled receptors activating phospholipase C, which hydrolyses PI (4,5)P2 to diacylglycerol (DAG) and inositol triphosphate (IP3), with the latter releasing Ca 2+ from internal stores. The depletion of PI(4,5)P2 caused by hydrolysis and the resulting loss of membrane interaction of the C-terminus inhibits TREK channels [30,32,33]. TREK channels are also inhibited by the phosphorylation of multiple residues on the cytoplasmic C-terminus domain by protein kinase A and C following the stimulation of G-coupled receptors [12,[34][35][36].…”

Contribution of KCNQ and TREK Channels to the Resting Membrane Potential in Sympathetic Neurons at Physiological Temperature

“…It is well known that RMP changes when I M is modulated through GPCRs by muscarinic, bradykinin, purinergic and angiotensin II agonists [10,32,33] or directly by blockers such as linopirdine and XE991 [10,29] in SCG neurons. In 1996, the first member of the K2P family was described [7] and this potassium channel family is also involved in the maintenance of the RMP and excitability [14,34]. Because TREK channels are very sensitive to temperature [35], the main objective of this work was to determine the contribution of each of these two currents (M and TREK) to the resting membrane potential at physiological temperatures.…”

“…Nevertheless, we have seen recently that TREK-2 channels in mouse SCG neurons are also inhibited by the muscarinic agonist oxo-M through G-proteins and a second messenger cascade [13]. Moreover, inhibition of TREK-2 current [14] and M-current [15] by bradykinin hormone depolarizes the RMP. On the other hand, the inhibition of TREK currents with fluoxetine [16] produced a depolarization of the membrane potential and reduced the latency to the first evoked action potential, without affecting adaptation [6] at room temperature.…”