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Activation of the Epithelial‐to‐Mesenchymal Transition Factor Snail Mediates Acetaldehyde‐Induced Intestinal Epithelial Barrier Disruption
Author(s) -
Elamin Elhaseen,
Masclee Ad,
Troost Freddy,
Dekker Jan,
Jonkers Daisy
Publication year - 2014
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/acer.12234
Subject(s) - occludin , paracellular transport , tight junction , claudin , snail , small interfering rna , adherens junction , microbiology and biotechnology , fluorescein isothiocyanate , epithelial–mesenchymal transition , chemistry , reactive oxygen species , biology , biochemistry , cadherin , downregulation and upregulation , permeability (electromagnetism) , transfection , cell , ecology , physics , quantum mechanics , membrane , gene , fluorescence
Background Acetaldehyde ( A c H ) is mutagenic and can reach high concentrations in colonic lumen after ethanol consumption and is associated with intestinal barrier dysfunction and an increased risk of progressive cancers, including colorectal carcinoma. Snail, the transcription factor of epithelial–mesenchymal transition, is known to down‐regulate expression of tight junction ( TJ ) and adherens junction ( AJ ) proteins, resulting in loss of epithelial integrity, cancer progression, and metastases. As A c H is mutagenic, the role of Snail in the A c H ‐induced disruption of intestinal epithelial TJ s deserves further investigation. Our aim was to investigate the role of oxidative stress and Snail activation in A c H ‐induced barrier disruption in C aco‐2 monolayers. Methods The monolayers were exposed from the apical side to A c H  ±  L ‐cysteine. Reactive oxygen species ( ROS ) generation and Snail activation were assessed by ELISA and immunofluorescence. Paracellular permeability, localization, and expression of ZO ‐1, occludin, E ‐cadherin, and β‐catenin were examined using transepithelial electrical resistance ( TEER ), fluorescein isothiocyanate–labeled dextran 4 kDa ( FITC ‐ D 4), immunofluorescence, and ELISA , respectively. Involvement of Snail was further addressed by inhibiting Snail using small interfering RNA (si RNA ). Results Exposure to 25 μM A c H increased ROS generation and ROS ‐dependently induced Snail phosphorylation. In addition, A c H increased paracellular permeability (decrease in TEER and increase in FITC ‐ D 4 permeation) in association with redistribution and decrease of TJ and AJ protein levels, which could be attenuated by L ‐cysteine. Knockdown of Snail by si RNA attenuated the A c H ‐induced redistribution and decrease in the TJ and AJ proteins, in association with improvement of the barrier function. Conclusions Our data demonstrate that oxidative stress‐mediated Snail phosphorylation is likely a novel mechanism contributing to the deleterious effects of A c H on the TJ and AJ , and intestinal barrier function.

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