14‐3‐3 Proteins regulate K_2P5.1 surface expression on T lymphocytes

Abstract

K2P5.1 channels (also called TASK‐2 or Kcnk5) have already been shown to be relevant in the pathophysiology of autoimmune disease because they are known to be upregulated on peripheral and central T lymphocytes of multiple sclerosis (MS) patients. Moreover, overexpression of K2P5.1 channels in vitro provokes enhanced T‐cell effector functions. However, the molecular mechanisms regulating intracellular K2P5.1 channel trafficking are unknown so far. Thus, the aim of the study is to elucidate the trafficking of K2P5.1 channels on T lymphocytes. Using mass spectrometry analysis, we have identified 14‐3‐3 proteins as novel binding partners of K2P5.1 channels. We show that a non‐classical 14‐3‐3 consensus motif (R‐X‐X‐pT/S‐x) at the channel's C‐terminus allows the binding between K2P5.1 and 14‐3‐3. The mutant K2P5.1/S266A diminishes the protein‐protein interaction and reduces the amplitude of membrane currents. Application of a non‐peptidic 14‐3‐3 inhibitor (BV02) significantly reduces the number of wild‐type channels in the plasma membrane, whereas the drug has no effect on the trafficking of the mutated channel. Furthermore, blocker application reduces T‐cell effector functions. Taken together, we demonstrate that 14‐3‐3 interacts with K2P5.1 and plays an important role in channel trafficking.

The Potassium Channel Odyssey: Mechanisms of Traffic and Membrane Arrangement

“…K 2P 5.1 associates with 14-3-3 at the early stages of biogenesis in the ER. This association facilitates the anterograde traffic of the channel to reach the plasma membrane [114].…”

Acetylcholine‐dependent upregulation of TASK‐1 channels in thalamic interneurons by a smooth muscle‐like signalling pathway

“…, ; Fernandez‐Orth et al . ). However the fast time course of minutes of the OxoM‐induced response may point to increased channel opening in the present study.…”

“…From our data it is not clear whether direct phosphorylation of the channel protein and/or additional interacting proteins like the adapter protein 14-3-3 contributes to TASK-1 modulation by TK. While mutations at the single TK phosphorylation site (Y323) within the TASK-1 protein were not found to be involved in genistein modulation of the channel (Gierten et al 2008), several members of the TASK channel family reveal 14-3-3-dependent surface expression which is sensitive to the phosphorylation/dephosphorylation status of the trafficking control region of the channels (Kilisch et al 2015(Kilisch et al , 2016Fernandez-Orth et al 2016). However the fast time course of minutes of the OxoM-induced response may point to increased channel opening in the present study.…”

The kinase activity of the channel-kinase protein TRPM7 regulates stability and localization of the TRPM7 channel in polarized epithelial cells

“…S8). 14-3-3 proteins have been shown to regulate the cellular localization of ion channels and transporters (55)(56)(57)(58). Because TRPM7 kinase-inactivation affected the channel's localization and TRPM7's interaction with 14-3-3 is autophosphorylation-dependent, we investigated whether mutations in the 14-3-3-binding sites could affect the cellular localization of the channel (Fig.…”