Histamine Treatment Induces Rearrangements of Orthogonal Arrays of Particles (OAPs) in Human AQP4-Expressing Gastric Cells

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 t...

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Bibliographic Details
Published in:The Journal of cell biology 2001-09, Vol.154 (6), p.1235-1243
Main Authors: Carmosino, Monica, Procino, Giuseppe, Nicchia, Grazia Paola, Mannucci, Roberta, Verbavatz, Jean-Marc, Gobin, Renèe, Svelto, Maria, Valenti, Giovanna
Format: Article
Language:English
Subjects:
Animals
Aquaporin 4
Aquaporins - metabolism
Cell Line
Cell lines
Cell membranes
Cells
Colforsin - pharmacology
Dimerization
Epithelial cells
Epithelial Cells - chemistry
Epithelial Cells - ultrastructure
Freeze Fracturing
Gastric parietal cells
Histamine
Histamine - pharmacology
Histamines
Humans
Membranes
Microscopy, Electron
Osmosis - drug effects
Particle Size
Plasma
Rats
Receptors
Secretion
Stomach
Stomach - cytology
Transfection
Water channels
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Summary: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× 10-4to 16.37 ± 0.5× 10-4cm/s at 20°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, Pfdecreased by ∼35% in 20-min histamine-stimulated cells. Both Pfand 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.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.200103010