PKCα regulates TMEM16A-mediated Cl− secretion in human biliary cells

TMEM16A is a newly identified Ca2+-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 Ca2+ concentration ([Ca2+]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 Ca2+-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 Go6976) inhibition of PKCα. Intracellular dialysis with recombinant PKCα activated Cl− curren...