title: PKCα regulates TMEM16A-mediated Cl⁻ secretion in human biliary cells.
abstract: TMEM16A is a newly identified Ca(2+)-activated Cl(-) channel in biliary epithelial cells (BECs) that is important in biliary secretion. While extracellular ATP stimulates TMEM16A via binding P2 receptors and increasing intracellular Ca(2+) concentration ([Ca(2+)]i), the regulatory pathways have not been elucidated. Protein kinase C (PKC) contributes to ATP-mediated secretion in BECs, although its potential role in TMEM16A regulation is unknown. To determine whether PKCα regulates the TMEM16A-dependent membrane Cl(-) transport in BECs, studies were performed in human biliary Mz-cha-1 cells. Addition of extracellular ATP induced a rapid translocation of PKCα from the cytosol to the plasma membrane and activation of whole cell Ca(2+)-activated Cl(-) currents. Currents demonstrated outward rectification and reversal at 0 mV (properties consistent with TMEM16A) and were inhibited by either molecular (siRNA) or pharmacologic (PMA or Gö6976) inhibition of PKCα. Intracellular dialysis with recombinant PKCα activated Cl(-) currents with biophysical properties identical to TMEM16A in control cells but not in cells after transfection with TMEM16A siRNA. In conclusion, our studies demonstrate that PKCα is coupled to ATP-stimulated TMEM16A activation in BECs. Targeting this ATP-Ca(2+)-PKCα signaling pathway may represent a therapeutic strategy to increase biliary secretion and promote bile formation.
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Amal K
authors.initials: AK
authors.lastname: Dutta
authors.forename: Al-Karim
authors.initials: AK
authors.lastname: Khimji
authors.affiliation: Department of Internal Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Songling
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas; and.
authors.forename: Zemfira
authors.initials: Z
authors.lastname: Karamysheva
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Akiko
authors.initials: A
authors.lastname: Fujita
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas;
authors.forename: Charles
authors.initials: C
authors.lastname: Kresge
authors.affiliation: Department of Internal Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Don C
authors.initials: DC
authors.lastname: Rockey
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; drew.feranchak@utsouthwestern.edu.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Feranchak
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000075369:Anoctamin-1; D001652:Bile Ducts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D034622:RNA Interference; D015398:Signal Transduction; D014162:Transfection
chemical_list: C476213:ANO1 protein, human; D000075369:Anoctamin-1; D018118:Chloride Channels; D002712:Chlorides; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D000255:Adenosine Triphosphate; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha; D002118:Calcium
keywords: ATP; Cl− channel; PKCα; TMEM16A; cholangiocytes