Calcitonin receptor-mediated CFTR activation in human intestinal epithelial cells

Hongguang Liu, Amika Singla, Mei Ao, Ravinder K. Gill, Jayashree Venkatasubramanian, Mrinalini C. Rao, Waddah A. Alrefai, Pradeep K. Dudeja

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

High levels of calcitonin (CT) observed in medullary thyroid carcinoma and other CT-secreting tumours cause severe diarrhoea. Previous studies have suggested that CT induces active chloride secretion. However, the involvement of CT receptor (CTR) and the molecular mechanisms underlying the modulation of intestinal electrolyte secreting intestinal epithelial cells have not been investigated. Therefore, current studies were undertaken to investigate the direct effects of CT on ion transport in intestinal epithelial cells. Real time quantitative RT-PCR and Western blot analysis demonstrated the expression of CTR in intestinal epithelial T84 cells. Exposure of T84 cells to CT from the basolateral but not from apical side significantly increased short circuit current (I SC) in a dose-dependent manner that was blocked by 1 μM of CTR antagonist, CT8-32. CT-inducedI SC was blocked by replacing chloride in the bath solutions with equimolar gluconate and was significantly inhibited by the specific cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor, CFTR 127inh. Further, biotinylation studies showed that CT increased CFTR levels on the apical membrane. The presence of either the Ca 2+ chelator, bis(2-aminophenoxy)ethane tetraacetic acid-acetoxymethyl (BAPTA-AM) ester or the protein kinase A (PKA) inhibitor, H89, significantly inhibitedI SC induced by CT (∼32-58% reduction). Response to CT was retained after permeabilization of the basolateral or the apical membranes of T84 cells with nystatin. In conclusion, the activation of CTR by CT induced chloride secretion across T84 monolayersviaCFTR channel and the involvement of PKA- and Ca 2+-dependent signalling pathways. These data elucidate the molecular mechanisms underlying CT-induced diarrhoea.

Original languageEnglish (US)
Pages (from-to)2697-2705
Number of pages9
JournalJournal of Cellular and Molecular Medicine
Volume15
Issue number12
DOIs
StatePublished - Dec 1 2011

Keywords

  • CFTR
  • Calcitonin
  • Calcitonin receptor
  • Chloride secretion
  • Diarrhoea

ASJC Scopus subject areas

  • Molecular Medicine
  • Cell Biology

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    Liu, H., Singla, A., Ao, M., Gill, R. K., Venkatasubramanian, J., Rao, M. C., Alrefai, W. A., & Dudeja, P. K. (2011). Calcitonin receptor-mediated CFTR activation in human intestinal epithelial cells. Journal of Cellular and Molecular Medicine, 15(12), 2697-2705. https://doi.org/10.1111/j.1582-4934.2011.01264.x