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Cyclic Stretch Disrupts Apical Junctional Complexes in Caco-2 Cell Monolayers by a JNK-2, c-Src and MLCK-Dependent Mechanism

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AJP Gastrointestinal and Liver Physiology

Published online on

Abstract

The intestinal epithelium is subjected to various types of mechanical stress. In this study, we investigated the impact of cyclic stretch on tight junction and adherens junction integrity in Caco-2 cell monolayers. Stretch for 2 hours resulted in dramatic modulation of tight junction protein distribution from linear organization into wavy structure. Continuation of cyclic stretch for 6 hours led to redistribution of tight junction proteins from the intercellular junctions into intracellular compartment. Disruption of tight junctions was associated with redistribution of adherens junction proteins, E-cadherin and β-catenin, and dissociation of the actin cytoskeleton at the actomyosin belt. Stretch activates JNK2, c-Src and MLCK. Inhibition of JNK, Src kinase or MLCK activity and knockdown of JNK2 or c-Src attenuated stretch-induced disruption of tight junctions, adherens junctions and actin cytoskeleton. Stretch increased tyrosine phosphorylation of occludin, ZO-1, E-cadherin and β-catenin. Inhibition of JNK or Src kinase attenuated stretch-induced occludin phosphorylation. Immunofluorescence localization indicated that phospho-MLC co-localizes with the vesicle-like actin structure at the actomyosin belt in stretched cells. On the other hand, phospho-c-Src co-localizes with the actin at the apical region of cells. This study demonstrates that cyclic stretch disrupts tight junctions and adherens junctions by a JNK2, c-Src and MLCK-dependent mechanism.