Metabolic regulation of the two-pore domain potassium channel TASK-1

Abstract

TASK-1 is a two-pore potassium ion channel and implicated in the maintenance of cell membrane potential. Little is known about the traffic regulation of TASK-1 under metabolic stress. The present study was designed to explore whether cell surface expression of TASK-1 is modulated by hypoxia. The trafficking of recombinant TASK-1 channels was studied in HEK293T cells under hypoxia induced by sodium cyanide (NaCN). Incubation of cells with NaCN significantly reduced TASK-1 fluorescence intensity at cell periphery, and this effect was inhibited by pretreatment with bisindolylmaleimide (BIM), a specific protein kinase C (PKC) inhibitor. Similar results were confirmed by quantifying extracellular HA-tagged TASK-1 on the cell surface using chemiluminescence assay. NaCN-induced reduction in TASK-1 at cell periphery was also prevented by co-expressing the dominant-negative dynamin 1 (K44E), or cholesterol depletion with MβCD, indicating a potential role of cholesterol and dynamin-dependent endocytosis in PKC-mediated reduction of cell surface TASK-1 by NaCN. Mutagenesis studies further showed that NaCN-induced reduction of TASK-1 at cell periphery was observed in cells expressing wild-type TASK-1 but not mutant TASK-1 with mutation of the dileucine motif (263-264 LL-AA) or the PKC phosphorylation consensus site (T400A). Moreover, Western blot analysis demonstrated that NaCN reduced the amount of wild-type TASK-1 but not the TASK-1 mutants (263-264 LL-AA and T400A) in the membrane fraction. In conclusion, our results demonstrate that cell surface TASK-1 channels are downregulated under metabolic inhibition, possibly through PKC-mediated endocytosis in a cholesterol and dynamin-dependent manner. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.