Acid stimulates E-cadherin surface expression on gastric epithelial cells to stabilize barrier functions via influx of calcium.
OBJECTIVE
E-cadherin, which is a [Ca2+]-dependent, homotypic cell-cell adhesion molecule, is expressed in gastrointestinal epithelial cells. Much has been learned about the down-regulation of E-cadherin expression in gastrointestinal tumours, Barrett's oesophageal dysplasia, and Crohn's disease, but the functions of this molecule in normal gastrointestinal mucosa are less known.


METHODS
In this study, we investigated the relationship between E-cadherin expression and permeability using rat cultured gastric and intestinal epithelial cells following a 30-min exposure to various pH solutions. We also investigated the participation of [Ca2+] in these events.


RESULTS
E-cadherin expression increased under acid (pH 4) but not alkali (pH 10 or 11) exposure only for gastric epithelial cells. Gastric epithelial permeability was maintained only against acid exposure while intestinal permeability increased under both conditions. Transient influx of [Ca2+] was only observed for gastric epithelial cells just after acid exposure.


CONCLUSIONS
These findings suggest that E-cadherin expression on gastric epithelium stabilizes the epithelial barrier against acid, probably through influx of [Ca2+]. This event is thought to be one of the protective mechanisms in gastric mucosa against acid back-diffusion, which is one of the causes of peptic ulcer formation.
Second Department of Internal Medicine, Aichi Medical University, Japan. mari@med.nagoya-cu.ac.jp
M
M
Mizuno
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N
Okayama
K
K
Kasugai
T
T
Yoshida
M
M
Miyata
M
M
Nitta
H
H
Kataoka
S
S
Akita
T
T
Joh
M
M
Itoh
K
K
Asai
T
T
Kato
D000143:Acids; D000468:Alkalies; D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000032:analysis / Q000096:biosynthesis*; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002470:Cell Survival; D002478:Cells, Cultured; D004847:Epithelial Cells; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000143:Acids; D000468:Alkalies; D015820:Cadherins; D002118:Calcium