Functional expression of TREK-2 in insulin-secreting MIN6 cells.
Insulin secretion from pancreatic beta cells is partly regulated by cell membrane potential. Background K+ channels that stabilize the resting membrane potential would suppress excitability and insulin secretion. Recent studies show that members of the two-pore domain K+ (K2P) channel family behave as background K+ channels in many excitable cells. Therefore, the expression of K2P channels was studied in insulin-secreting MIN6 cells. Reverse transcriptase PCR showed that, among nine K2P channels tested, TASK-1, TASK-2, TASK-3, TREK-2, and TRESK-2 were expressed in MIN6 cells. Cell-attached recordings on MIN6 cells revealed five types of K+ channels that were open at rest. Two were ATP-sensitive and Ca2+-activated K+ channels, as judged by their sensitivity to ATP and Ca2+, respectively, and single-channel conductance. Among five K2P channels, only TREK-2 could be clearly identified in MIN6 cells. The molecular identity of two other K+ channels is not yet known. TREK-2 in MIN6 cells was activated by arachidonic acid, membrane stretch, and low pH solution (pH 5.8). Arachidonic acid increased Ba2+-sensitive whole-cell current in MIN6 cell. These results suggest that TREK-2 contributes to the background K+ conductance in MIN6 cells, and may regulate depolarization-induced secretion of insulin.
Kang
Dawon
D
Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science/The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA.
Choe
Changyong
C
Kim
Donghee
D
D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D016718:Arachidonic Acid / Q000737:chemistry / Q000378:metabolism; D001464:Barium / Q000737:chemistry; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000378:metabolism*; D008564:Membrane Potentials; D051379:Mice; D011188:Potassium / Q000737:chemistry; D015221:Potassium Channels / Q000096:biosynthesis*; D024683:Potassium Channels, Tandem Pore Domain; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D007328:Insulin; C503445:Kcnk10 protein, mouse; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D001464:Barium; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D011188:Potassium; D002118:Calcium