14-3-3 Proteins regulate K2P5.1 surface expression on T lymphocytes

K(2P)5.1 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 K(2P)5.1 channels in vitro provokes enhanced T-cell effector functions. However, the molecular mechanisms regulating intracellular K(2P)5.1 channel trafficking are unknown so far. Thus, the aim of the study is to elucidate the trafficking of K(2P)5.1 channels on T lymphocytes. Using mass spectrometry analysis, we have identified 14-3-3 proteins as novel binding partners of K(2P)5.1 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 K(2P)5.1 and 14-3-3. The mutant K(2P)5.1/S266A diminishes the proteinprotein interaction and reduces the amplitude of membrane currents. Application of a nonpeptidic 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 K(2P)5.1 and plays an important role in channel trafficking.