Folliculin Controls Lung Alveolar Enlargement and Epithelial Cell Survival through E-Cadherin, LKB1, and AMPK

Abstract Background Disruption of the gut barrier is an essential mechanism of inflammatory bowel diseases (IBDs) contributing to the development of mucosal inflammation. A hallmark of barrier disruption is the disassembly of epithelial adherens junctions (AJs) driven by decreased expression of a major AJ protein, E-cadherin. A group of isoxazole compounds, such as E-cadherin-upregulator (ECU) and ML327, were previously shown to stimulate E-cadherin expression in poorly differentiated human cancer cells. This study was designed to examine whether these isoxazole compounds can enhance and protect model intestinal epithelial barriers in vitro. Methods The study was conducted using T84, SK-CO15, and HT-29 human colonic epithelial cell monolayers. Disruption of the epithelial barrier was induced by pro-inflammatory cytokines, tumor necrosis factor-α, and interferon-γ. Barrier integrity and epithelial junction assembly was examined using different permeability assays, immunofluorescence labeling, and confocal microscopy. Epithelial restitution was analyzed using a scratch wound healing assay. Results E-cadherin-upregulator and ML327 treatment of intestinal epithelial cell monolayers resulted in several barrier-protective effects, including reduced steady-state epithelial permeability, inhibition of cytokine-induced barrier disruption and junction disassembly, and acceleration of epithelial wound healing. Surprisingly, these effects were not due to upregulation of E-cadherin expression but were mediated by multiple mechanisms including inhibition of junction protein endocytosis, attenuation of cytokine-induced apoptosis, and activation of promigratory Src and AKT signaling. Conclusions Our data highlight ECU and ML327 as promising compounds for developing new therapeutic strategies to protect the integrity and accelerate the restitution of the intestinal epithelial barrier in IBD and other inflammatory disorders.

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Remodeling the cell surface distribution of membrane proteins during the development of epithelial cell polarity.

The Journal of Cell Biology ◽

10.1083/jcb.116.4.889 ◽

1992 ◽

Vol 116 (4) ◽

pp. 889-899 ◽

Cited By ~ 60

Author(s):

D A Wollner ◽

K A Krzeminski ◽

W J Nelson

Keyword(s):

Epithelial Cell ◽

Membrane Proteins ◽

Cell Surface ◽

Mdck Cells ◽

Apical Cell ◽

Cell Contact ◽

Surface Polarity ◽

Lateral Membrane ◽

E Cadherin ◽

Cell Cell

The development of polarized epithelial cells from unpolarized precursor cells follows induction of cell-cell contacts and requires resorting of proteins into different membrane domains. We show that in MDCK cells the distributions of two membrane proteins, Dg-1 and E-cadherin, become restricted to the basal-lateral membrane domain within 8 h of cell-cell contact. During this time, however, 60-80% of newly synthesized Dg-1 and E-cadherin is delivered directly to the forming apical membrane and then rapidly removed, while the remainder is delivered to the basal-lateral membrane and has a longer residence time. Direct delivery of greater than 95% of these proteins from the Golgi complex to the basal-lateral membrane occurs greater than 48 h later. In contrast, we show that two apical proteins are efficiently delivered and restricted to the apical cell surface within 2 h after cell-cell contact. These results provide insight into mechanisms involved in the development of epithelial cell surface polarity, and the establishment of protein sorting pathways in polarized cells.

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Digestion of epithelial tight junction proteins by the commensal Clostridium perfringens

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00316.2012 ◽

2013 ◽

Vol 305 (10) ◽

pp. G740-G748 ◽

Cited By ~ 14

Author(s):

Mihaela Pruteanu ◽

Fergus Shanahan

Keyword(s):

Epithelial Cell ◽

Tight Junction ◽

Clostridium Perfringens ◽

Culture Supernatant ◽

Dependent Manner ◽

Intestinal Epithelial ◽

Tight Junction Proteins ◽

Epithelial Tight Junction ◽

Junction Proteins ◽

E Cadherin

The enteric microbiota contributes to the pathogenesis of inflammatory bowel disease, but the pathways involved and bacterial participants may vary in different hosts. We previously reported that some components of the human commensal microbiota, particularly Clostridium perfringens ( C. perfringens), have the proteolytic capacity for host matrix degradation and reduce transepithelial resistance. Here, we examined the C. perfringens-derived proteolytic activity against epithelial tight junction proteins using human intestinal epithelial cell lines. We showed that the protein levels of E-cadherin, occludin, and junctional adhesion molecule 1 decrease in colonic cells treated with C. perfringens culture supernatant. E-cadherin ectodomain shedding in C. perfringens-stimulated intestinal epithelial cells was detected with antibodies against the extracellular domain of E-cadherin, and we demonstrate that this process occurs in a time- and dose-dependent manner. In addition, we showed that the filtered sterile culture supernatant of C. perfringens has no cytotoxic activity on the human intestinal cells at the concentrations used in this study. The direct cleavage of E-cadherin by the proteases from the C. perfringens culture supernatant was confirmed by C. perfringens supernatant-induced in vitro degradation of the human recombinant E-cadherin. We conclude that C. perfringens culture supernatant mediates digestion of epithelial cell junctional proteins, which is likely to enable access to the extracellular matrix components by the paracellular pathway.

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