Stress-Kinase Regulation of TASK-1 and TASK-3

Susanne Rinné, Aytug K. Kiper, Constanze Schmidt, Beatriz Ortiz-Bonnin, Simone Zwiener, Guiscard Seebohm, Niels Decher
2017 Cellular Physiology and Biochemistry  
Background/Aims: TASK channels belong to the two-pore-domain potassium (K 2P ) channel family. TASK-1 is discussed to contribute to chronic atrial fibrillation (AFib) and has been together with uncoupling protein 1 found as a marker protein of brown adipose tissue (BAT) fat. In addition, TASK-1 was linked in a genome-wide association study to an increased body mass index. A recent study showed that TASK-1 inhibition is causing obesity in mice by a BAT whitening and that these effects are linked
more » ... effects are linked to the mineralo corticoid receptor pathway, albeit the mechanism remained elusive. Therefore, we aimed to probe whether K 2P channels are regulated by serum-and glucocorticoid-inducible kinases (SGKs) which are known to modify many cellular functions by modulating ion channels. Methods: To this end we used functional co-expression studies and chemiluminescence-assays in Xenopus oocytes, together with fluorescence imaging and quantitative PCR experiments. Results: SGKs and proteinkinase B (PKB) induced a strong, dose-and time-dependent current reduction of TASK-1 and TASK-3. SGK co-expression reduced the surface expression of TASK-1/3, leading to a predominant localization of the channels into late endosomes. The down regulation of TASK-3 channels was abrogated by the dynamin inhibitor dynasore, confirming a role of SGKs in TASK-1/3 channel endocytosis. Conclusion: Stress-mediated changes in SGK expression pattern or activation is likely to alter TASK-1/3 expression at the surface membrane. The observed TASK-1 regulation might contribute to the pathogenesis of chronic AFib and provide a mechanistic link between increased mineralo corticoid levels and TASK-1 reduction, both linked to BAT whitening. Expression of TASK channels in oocytes Stage IV and V oocytes were injected with cRNA. For co-expression experiments 25 ng cRNA of the kinases (SGK1, SGK2, SGK3, PKB, PDK or AS160) were used. In Fig. 3 , 50 pg TASK-3 was co-injected with 50 pg (1:1), 500 pg (1:10), 5 ng (1:100) or 25 ng (1:500) SGK-2 cRNA. Standard two-microelectrode voltageclamp (TEVC) recordings were performed at room temperature (20-22°C) 1-3 days after cRNA injection with a TurboTEC 10CD (npi) amplifier and a Digidata 1200 Series (Axon Instruments) as A/D converter. Micropipettes were made from borosilicate glass capillaries GB 150TF-8P (Science Products) and pulled with a DMZ-Universal Puller (Zeitz). Recording pipettes had a resistance of 0.5-1.5 MΩ and were filled with 3 M KCl solution. ND96 was used as recording solution containing in mM: NaCl 96, KCl 2, CaCl 2 1.8, MgCl 2 1, HEPES 5 (pH 7.5). Chemiluminescence assay Surface expression of the HA-tagged TASK-1 channel construct was analyzed in Xenopus oocytes. Two days after cRNA injection oocytes were incubated for 30 min in ND96 solution containing 1% bovine serum
doi:10.1159/000485402 pmid:29179200 fatcat:ytuicjia6radfnemk7cwg55clu