Glycogen Synthase Kinase 3 (GSK-3) influences epithelial barrier function by regulating Occludin, Claudin-1 and E-cadherin expression

• Type of Material: Article
• Authors: Eric A. Severson, Emory University; Mike Kwon, Emory University; Roland S. Hilgarth, Emory University; Charles Parkos, Emory University; Asma Nusrat, Emory University
• Language: English
• Date: 2010-07-02
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2010 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bbrc.2010.05.164
• Title of Journal or Parent Work: Biochemical and Biophysical Research Communications
• ISSN: 0006-291X
• Volume: 397
• Issue: 3
• Start Page: 592
• End Page: 597
• Grant/Funding Information: This study was supported by National Institutes of Health grants DK55679 and DK59888 (to A.N.) as well as DK72564, DK61379, and DK79392 (to C.P.).
• Keywords: Occludin; Claudin-1; Glycogen Synthase Kinase 3 (GSK-3); Paracellular Permeability; Apical Junctional Complex (AJC); Epithelial-Mesenchymal Transition (EMT)
• Research Categories: Health Sciences, Pathology

Abstract

The apical junctional complex (AJC) encompassing the tight junction (TJ) and adherens junction (AJ) plays a pivotal role in regulating epithelial barrier function and epithelial cell proliferative processes through signaling events that remain poorly characterized. A potential regulator of AJC protein expression is Glycogen Synthase Kinase-3 (GSK-3). GSK-3 is a constitutively active kinase that is repressed during epithelial-mesenchymal transition (EMT). In the present study, we report that GSK-3 activity regulates the structure and function of the AJC in polarized model intestinal (SK-CO15) and kidney (Madin-Darby Canine Kidney (MDCK)) epithelial cells. Reduction of GSK-3 activity, either by small molecule inhibitors or siRNA targeting GSK-3 alpha and beta mRNA, resulted in increased permeability to both ions and bulk solutes. Immunofluorescence labeling and immunoblot analyses revealed that the barrier defects correlated with decreased protein expression of AJC transmembrane proteins Occludin, Claudin-1 and E-cadherin without influencing other TJ proteins, Zonula Occludens-1 (ZO-1) and Junctional Adhesion Molecule A (JAM-A). The decrease in Occludin and E-cadherin protein expression correlated with downregulation of the corresponding mRNA levels for these respective proteins following GSK-3 inhibition. These observations implicate an important role of GSK-3 in the regulation of the structure and function of the AJC that is mediated by differential modulation of mRNA transcription of key AJC proteins, Occludin, Claudin-1 and E-cadherin.