Vasoactive intestinal peptide and cystic fibrosis transmembrane conductance regulator contribute to the transepithelial calcium transport across intestinal epithelium-like Caco-2 monolayer

Abstract

Vasoactive intestinal peptide (VIP) as a neurocrine factor released by enteric neurons has been postulated to participate in the regulation of transcellular active calcium transport across intestinal epithelium, but the preceding evidence is scant and inconclusive. Herein, transepithelial calcium flux and epithelial electrical parameters were determined by Ussing chamber technique with radioactive tracer in the intestinal epithelium-like Caco-2 monolayer grown on Snapwell. After 3-day culture, Caco-2 cells expressed mRNA of calcium transporters, i.e., TRPV6, calbindin-D9k, PMCA1b and NCX1, and exhibited transepithelial resistance of ~200 Ω cm2, a characteristic of leaky epithelium similar to the small intestine. VIP receptor agonist was able to enhance transcellular calcium flux, whereas VIP receptor antagonist totally abolished calcium fluxes induced by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Since the intestinal cystic fibrosis transmembrane conductance regulator (CFTR) could be activated by VIP and calciotropic hormones, particularly parathyroid hormone, we sought to determine whether CFTR also contributed to the 1,25(OH)2D3-induced calcium transport. A selective CFTR inhibitor (20–200 μM CFTRinh-172) appeared to diminish calcium fluxes as well as transepithelial potential difference and short-circuit current, both of which indicated a decrease in electrogenic ion transport. On the other hand, 50 μM genistein—a molecule that could rapidly activate CFTR—was found to increase calcium transport. Our in silico molecular docking analysis confirmed direct binding of CFTRinh-172 and genistein to CFTR channels. In conclusion, VIP and CFTR apparently contributed to the intestinal calcium transport, especially in the presence of 1,25(OH)2D3, thereby supporting the existence of the neurocrine control of intestinal calcium absorption.

Multiple Regulatory Signals and Components in the Modulation of Bicarbonate Transporters

“…These results suggest that NHERF1 participates in the VIP-CFTR signaling cascade. Although VIP-mediated bicarbonate or chloride regulation is well-defined for CFTR function [ 66 , 67 , 68 , 69 ], the verification of regulatory interactions between VIP and other bicarbonate transporters should be investigated in the future.…”

Mechanism of Lactiplantibacillus plantarum regulating Ca2+ affecting the replication of PEDV in small intestinal epithelial cells

“…Ca 2+ is essential for the transmembrane transmission of biological signals, the regulation of glandular secretion, and the maintenance of acid-base homeostasis in the body ( Seo et al, 2015 ; Hussey et al, 2023 ). The maintenance of calcium homeostasis depends on various calcium channel proteins [e.g., transient receptor potential cation channel subfamily V member 6 (TRPV6) and stromal interaction molecule (STIM)] in the membranes of the endoplasmic reticulum, Golgi apparatus, mitochondria, and other cellular organelles ( Liou et al, 2005 ; Bibollet et al, 2023 ), transporters [sodium-calcium exchanger Na(+)/Ca(2+)-Exchange Protein 1 (NCX-1) ( Tarifa et al, 2022 )], and ion pumps [e.g., the cell membrane calcium pump, plasma membrane calcium-transporting ATPase 1 (PMCA1b)] ( Rodrat et al, 2022 ; Dai et al, 2023 ). Disruption of any of these components can affect calcium homeostasis.…”