Identification of ezrin as a target of gastrin in immature mouse gastric parietal cells.
The gastric acid-secreting parietal cell exhibits profound morphological changes on stimulation. Studies in gastrin null (Gas-KO) mice indicate that maturation of parietal cell function depends on the hormone gastrin acting at the G-protein-coupled cholecystokinin 2 receptor. The relevant cellular mechanisms are unknown. The application of differential mRNA display to samples of the gastric corpus of wild-type (C57BL/6) and Gas-KO mice identified the cytoskeletal linker protein, ezrin, as a previously unsuspected target of gastrin. Gastrin administered in vivo or added to gastric glands in vitro increased ezrin abundance in Gas-KO parietal cells. In parietal cells of cultured gastric glands from wild-type mice treated with gastrin, histamine or carbachol, ezrin was localized to vesicular structures resembling secretory canaliculi. In contrast, in cultured parietal cells from Gas-KO mice, ezrin was typically distributed in the cytosol, and this did not change after incubation with gastrin, histamine or carbachol. However, priming with gastrin for approximately 24 h, either in vivo prior to cell culture or by addition to cultured gastric glands, induced the capacity for secretagogue-stimulated localization of ezrin to large vesicular structures in Gas-KO mice. Similarly, in a functional assay based on measurement of intracellular pH, cultured parietal cells from Gas-KO mice were refractory to gastrin unless primed. The priming effect of gastrin was not attributable to the paracrine mediator histamine, but was prevented by inhibitors of protein kinase C and transactivation of the epidermal growth factor receptor. We conclude that in gastrin null mice there is reduced ezrin expression and a defect in ezrin subcellular distribution in gastric parietal cells, and that both can be reversed by priming with gastrin.
Pagliocca
Adelina
A
Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
Hegyi
Peter
P
Venglovecz
Viktoria
V
Rackstraw
Stephen A
SA
Khan
Zara
Z
Burdyga
Galina
G
Wang
Timothy C
TC
Dimaline
Rod
R
Varro
Andrea
A
Dockray
Graham J
GJ
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D005744:Gastric Acid / Q000378:metabolism; D005755:Gastrins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006632:Histamine / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010295:Parietal Cells, Gastric / Q000201:enzymology / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013997:Time Factors; D000099149:Ezrin
D003598:Cytoskeletal Proteins; D066246:ErbB Receptors; D005755:Gastrins; D006632:Histamine; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D000099149:Ezrin