Nerve growth factor-induced endocytosis of TWIK-related acid-sensitive K+ 1 channels in adrenal medullary cells and PC12 cells

Abstract

TWIK-related acid-sensitive K(+) (TASK) channels belong to a family of two-pore domain K(+) channels which produce background K(+) currents and are involved in important physiological functions, such as acidosis detection. We have recently elucidated that TASK1-like channels function as a sensor of acidosis in rat adrenal medullary (AM) cells and thus are indispensable for the endocrine function of AM cells. Here, using pharmacological, electrophysiological and biochemical methods, we studied how the expression and localisation of TASK1 channels are regulated in rat AM cells and PC12 cells. PC12 cells were found to express not only TASK1 but also TASK3 channels, and they did not constitute a heterodimer. The exposure of AM cells and PC12 cells to nerve growth factor (NGF) induced endocytosis of TASK1, but not TASK3 channels, in a clathrin-dependent manner. Mutation analysis of the TASK1 channel revealed that the dileucine motif (LL263/264) was involved in at least part of the endocytosis. Plating GFP-TASK1-expressing PC12 cells onto a sheet of fibroblasts, which produced NGF, resulted in the endocytosis of GFP-TASK1 channels. Additionally, the expression of TASK1 channels at the protein and mRNA levels was suppressed in PC12 cells treated with NGF for 2 weeks. These results indicate that NGF suppresses the expression of TASK1 channels in the plasma membrane via not only endocytosis but also the inhibition of gene transcription. Thus, no access to NGF may play a major role for the maintenance of TASK1 channels in the cell membrane in AM cells.

Lack of p11 expression facilitates acidity‐sensing function of TASK1 channels in mouse adrenal medullary cells

“…Cell culture and transfection were performed, as described by Matsuoka et al (23). Briefly, PC12 cells were cultured in DMEM (Thermo Fisher Scientific) supplemented with 10% fetal bovine serum (Nichirei Biosciences, Tokyo, Japan) at 37°C in an atmosphere of humidified air (95%) and CO 2 (5%).…”

Acid sensitive background potassium channels K2P3.1 and K2P9.1 undergo rapid dynamin-dependent endocytosis

“…Following 5 min of unstimulated endocytosis, comparable numbers of double-positive vesicles were observed for both channels (K 2P 3.1 37 ± 4.8 SEM; K 2P 9.1 53 ± 7.5 SEM; numbers Clearly, retrieval from the cell surface, degradation or recycling of K 2P channels will have an equally important role in regulating cell surface expression of these channels. Indeed, Gabriel et al 25 suggest that phosphorylation of K 2P 3.1 and recruitment of 14-3-3 may have a regulatory role in channel endocytosis, while Matsuoka et al 26 propose that nerve growth factor induces endocytosis of K 2P 3.1 in adrenal medullary cells. While these reports focus on regulators of stimulated endocytosis of TASK channels, to date, the molecular mechanism of K 2P channel retrieval from the cell surface has not been characterized.…”

Molecular mechanism for muscarinic M1 receptor‐mediated endocytosis of TWIK‐related acid‐sensitive K+ 1 channels in rat adrenal medullary cells

“…PC12 cells were seeded in 100 mm dishes and cultured to 70–80% confluence in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, as described previously (Matsuoka et al . ). The cells were transfected with GFP‐TASK1 plasmid and then serum‐starved for 12 h before the experiment (Matsuoka et al .…”

“…We have recently elucidated that TASK1 channels in the rat AM cell and its immortalized cell line, PC12 cells, are internalized in response to activation of tropomyosin receptor kinase A (TrkA) by nerve growth factor (NGF) (Matsuoka et al . ) and phosphorylation of tyrosine at 370 (Y370) in the C‐terminus of TASK1 by Src, a non‐receptor tyrosine kinase, is indispensable for TrkA‐mediated endocytosis (Matsuoka & Inoue, ). The aim of the present study is to determine whether or not mAChR stimulation induces the endocytosis of TASK1 channels in rat AM cells.…”