Altered expression, localization, and phosphorylation of epithelial junctional proteins in celiac disease.
We aimed to study the expression and localization of the molecular components of enterocyte junctions in celiac disease together with the level of tyrosine phosphorylation, a phenomenon known to affect their cellular distribution and function, and to explore the influence of proinflammatory cytokines. Duodenal biopsy specimens from patients with celiac disease and control subjects were used for immunoprecipitation, immunoblotting, and immunolocalization by using antioccludin, anti-zonula occludens (ZO)-1, anti-E-cadherin, anti-beta-catenin, and antiphosphotyrosine antibodies. The same procedures were carried out on filter-grown Caco-2 cells incubated in the absence or presence of interferon g and tumor necrosis factor a. In active celiac disease, the absence of a phosphorylated ZO-1 and the extensive phosphorylation of beta-catenin might be responsible for the absence of membranous localization of occludin and E-cadherin, respectively. The in vitro system showed an influence of the cytokines on the assembly of these complexes that proved the opposite to celiac samples as far as tight junctions were concerned because the presence of a phosphorylated ZO-1 enables occludin to localize in the membrane.
Ciccocioppo
Rachele
R
First Department of Medicine, IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy.
Finamore
Alberto
A
Ara
Carmen
C
Di Sabatino
Antonio
A
Mengheri
Elena
E
Corazza
Gino R
GR
D022005:Adherens Junctions / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002446:Celiac Disease / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D008875:Middle Aged; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism* / Q000473:pathology; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin / Q000378:metabolism
D015820:Cadherins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin; D019000:Phosphotyrosine