PKCα regulates TMEM16A-mediated Cl− secretion in human biliary cells
AK Dutta, AK Khimji, S Liu… - American Journal …, 2016 - journals.physiology.org
AK Dutta, AK Khimji, S Liu, Z Karamysheva, A Fujita, C Kresge, DC Rockey, AP Feranchak
American Journal of Physiology-Gastrointestinal and Liver …, 2016•journals.physiology.orgTMEM16A 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 …
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 …
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 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-Ca2+-PKCα signaling pathway may represent a therapeutic strategy to increase biliary secretion and promote bile formation.
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