Parathyroid hormone increases CFTR expression and function in Caco-2 intestinal epithelial cells

• Main Authors: Walailak Jantarajit, Kannikar Wongdee, Kornkamon Lertsuwan, Jarinthorn Teerapornpuntakit, Ratchaneevan Aeimlapa, Jirawan Thongbunchoo, Bartholomew S.J. Harvey, David N. Sheppard, Narattaphol Charoenphandhu
• Other Authors: Naresuan University
• Format: Article
• Published: 2020
• Subjects: Biochemistry, Genetics and Molecular Biology
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/49555
• Institution: Mahidol University

© 2020 Elsevier Inc. Parathyroid hormone (PTH) enhances cystic fibrosis transmembrane conductance regulator (CFTR)-mediated anion secretion by the human intestinal epithelial cell line Caco-2. With the patch-clamp and Ussing chamber techniques, we investigated how PTH stimulates CFTR activity in Caco-2 cells. Cell-attached recordings revealed that PTH stimulated the opening of CFTR-like channels, while impedance analysis demonstrated that PTH increased apical membrane capacitance, a measure of membrane surface area. Using ion substitution experiments, the PTH-stimulated increase in short-circuit current (Isc), a measure of transepithelial ion transport, was demonstrated to be Cl−- and HCO3−-dependent. However, the PTH-stimulated increase in Isc was unaffected by the carbonic anhydrase inhibitor acetazolamide, but partially blocked by the intermediate-conductance Ca2+-activated K+ channel (IKCa) inhibitor clotrimazole. TRAM-34, a related IKCa inhibitor, failed to directly inhibit CFTR Cl− channels in cell-free membrane patches, excluding its action on CFTR. In conclusion, PTH enhances CFTR-mediated anion secretion by Caco-2 monolayers by increasing the expression and function of CFTR in the apical membrane and IKCa activity in the basolateral membrane.