Histamine treatment induces rearrangements of orthogonal arrays of particles (OAPs) in human AQP4-expressing gastric cells
Monica Carmosino,Giuseppe Procino,Grazia Paola Nicchia,Roberta Mannucci,Jean-Marc Verbavatz,Renée Gobin,Maria Svelto,Giovanna Valenti +7 more
TLDR
Cell surface biotinylation experiments confirmed that AQP4 is internalized after 20 min of histamine exposure, which may account for the downregulation of water transport, the first evidence for short term rearrangement of OAPs in an established AQP 4-expressing cell line.Abstract:
To test the involvement of the water channel aquaporin (AQP)-4 in gastric acid physiology, the human gastric cell line (HGT)-1 was stably transfected with rat AQP4. AQP4 was immunolocalized to the basolateral membrane of transfected HGT-1 cells, like in native parietal cells. Expression of AQP4 in transfected cells increased the osmotic water permeability coefficient (Pf) from 2.02 +/- 0.3 x 10-4 to 16.37 +/- 0.5 x 10-4 cm/s at 20 degrees C. Freeze-fracture EM showed distinct orthogonal arrays of particles (OAPs), the morphological signature of AQP4, on the plasma membrane of AQP4-expressing cells. Quantitative morphometry showed that the density of OAPs was 2.5 +/- 0.3% under basal condition and decreased by 50% to 1.2 +/- 0.3% after 20 min of histamine stimulation, mainly due to a significant decrease of the OAPs number. Concomitantly, Pf decreased by approximately 35% in 20-min histamine-stimulated cells. Both Pf and OAPs density were not modified after 10 min of histamine exposure, time at which the maximal hormonal response is observed. Cell surface biotinylation experiments confirmed that AQP4 is internalized after 20 min of histamine exposure, which may account for the downregulation of water transport. This is the first evidence for short term rearrangement of OAPs in an established AQP4-expressing cell line.read more
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Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells *
Takuto Fujii,Yuji Takahashi,Akira Ikari,Magotoshi Morii,Yoshiaki Tabuchi,Kazuhiro Tsukada,Noriaki Takeguchi,Hideki Sakai +7 more
TL;DR: The results indicate that the K+-Cl- cotransport by KCC4 is tightly coupled with H+/K+ antiport by H+,K+-ATPase, resulting in HCl accumulation in SAV.
Journal ArticleDOI
Multi-parametric approach to identify coffee components that regulate mechanisms of gastric acid secretion.
Malte Rubach,Roman Lang,Elisabeth Seebach,Mark M. Somoza,Thomas Hofmann,Veronika Somoza,Veronika Somoza +6 more
TL;DR: By applying a multi-parametric approach, N-MP was shown to effectively down-regulate mechanisms of gastric acid secretion in human parietal gastric cells.
Journal ArticleDOI
AQP4 plasma membrane trafficking or channel gating is not significantly modulated by phosphorylation at COOH-terminal serine residues
TL;DR: Phosphorylation of six different serine residues in the COOH terminus of AQP4 appears not to be required for proper plasma membrane localization of AQp4 or to act as a molecular switch to gate the water channel.
Journal ArticleDOI
Activity-guided fractionation to characterize a coffee beverage that effectively down-regulates mechanisms of gastric acid secretion as compared to regular coffee
TL;DR: The work presented here aimed at the characterization of a coffee beverage that effectively down-regulates mechanisms of proton secretion in human gastric cells (HGT-1) and verified this antisecretory activity of N-MP in coffee beverages.
Journal ArticleDOI
AQP4 transfected into mouse cholangiocytes promotes water transport in biliary epithelia.
TL;DR: A novel AQP4‐transfected polarized mouse cholangiocyte cell line suitable for functional studies of transepithelial water transport is established and the importance of this AQP in water transport across biliary epithelia is defined.
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