ATP-activated chloride permeability in biliary epithelial cells is regulated by calmodulin-dependent protein kinase II.
Previous studies in freshly isolated rat biliary epithelial cells and in the human cholangiocarcinoma cell line Mz-ChA-1 have demonstrated that ATP activates a calcium-dependent chloride conductance. The coupling between the rise in intracellular calcium and activation of chloride channels has not previously been investigated. In the present study, we evaluated the potential role of calmodulin-dependent protein kinase II (CaMKII) in ATP-activated chloride permeability in Mz-ChA-1 cells. ATP stimulated [125I] efflux, a marker for Cl- movement. Peak efflux rates were inhibited by approximately 60% in cells pretreated with the calmodulin antagonist, W-7. In whole-cell patch clamp recordings, ATP and ionomycin activated calcium-dependent Cl- currents. Pretreatment of cells with the CaMKII inhibitor KN-62 blocked activation by either agent. It is concluded that calcium-dependent activation of chloride currents in Mz-ChA-1 cells is coupled to a CaMKII-dependent process.
McGill
J M
JM
Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-5121.
Yen
M S
MS
Basavappa
S
S
Mangel
A W
AW
Kwiatkowski
A P
AP
D000255:Adenosine Triphosphate / Q000378:metabolism; D001652:Bile Ducts / Q000166:cytology / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D008565:Membrane Proteins / Q000378:metabolism; D018408:Patch-Clamp Techniques; D013449:Sulfonamides / Q000494:pharmacology
C505032:CFTR protein, human; D002147:Calmodulin; D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D013449:Sulfonamides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C017967:W 7; D000255:Adenosine Triphosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases