Parathyroid hormone (PTH) rapidly enhances CFTR-mediated HCO₃⁻ secretion in intestinal epithelium-like Caco-2 monolayer: a novel ion regulatory action of PTH

Abstract

Laohapitakworn S, Thongbunchoo J, Nakkrasae L, Krishnamra N, Charoenphandhu N. Parathyroid hormone (PTH) rapidly enhances CFTR-mediated HCO 3 Ϫ secretion in intestinal epithelium-like Caco-2 monolayer: a novel ion regulatory action of PTH.

Vitamin D-Enhanced Duodenal Calcium Transport

“…The presence of PTH, PTHrP, and their receptors in the same intestinal regions/cell lines, therefore, implicated the possibility of autocrine and paracrine actions of PTH and/or PTHrP (Li et al, 1995;Nemere & Larsson, 2002). Besides calciotropic action, PTH also plays an important role in regulating intestinal transport of other ions, such as phosphate and bicarbonate (Laohapitakworn, Thongbunchoo, Nakkrasae, Krishnamra, & Charoenphandhu, 2011;Nemere, 1996). By using perfused duodenal loop, PTH was found to stimulate phosphate absorption in the chick duodenum (Nemere, 1996), while an in vitro experiment in Caco-2 monolayer revealed that PTH rapidly and directly stimulated apical bicarbonate secretion through cystic fibrosis transmembrane conductance regulator in protein kinase A-and PI3K-dependent manner Laohapitakworn et al, 2011).…”

Emerging role of cystic fibrosis transmembrane conductance regulator as an epigenetic regulator: linking environmental cues to microRNAs

“…68 In addition, CFTR channel activity is known to be regulated by extracellular ion concentrations, including Cl À49 and HCO À 3 . 69 Recently, parathyroid hormone (PTH) has been shown to rapidly enhance CFTR-mediated HCO À 3 secretion, 70 while the thyroid hormones tri-iodothyronine and thyroxine have been reported to exert acute inhibition of CFTR channel gating. 71 Interestingly, CFTR has also been shown to be robustly activated by membrane stretch, indicating its mechnosensitive gating properties.…”

How Phosphorylation and ATPase Activity Regulate Anion Flux though the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)

“…Both were applied at a concentration (C i ϭ 20 M) previously proven to completely inhibit PKA activity in live cells (51)(52)(53). Cells were incubated with the inhibitors for 30 -40 min before stimulation with CPT-cAMP or forskolin.…”