Epidermal growth factor receptor activation differentially regulates claudin expression and enhances transepithelial resistance in Madin-Darby canine kidney cells.
Tight junctions (TJs) are the most apical cell-cell junctions, and claudins, the recently identified TJ proteins, are critical for maintaining cell-cell adhesion in epithelial cell sheets. Based on their in vivo distribution and the results of overexpression studies, certain claudins, including claudin-1 and -4, are postulated to increase, whereas other claudins, especially claudin-2, are postulated to decrease the overall transcellular resistance. The overall ratio among claudins expressed in a cell/tissue has been hypothesized to define the complexity of TJs. Disruption of the TJs contributes to various human diseases, and a correlation between reduction of TJ function and tumor dedifferentiation has been postulated. The epidermal growth factor (EGF) receptor (EGFR) is overexpressed in a wide spectrum of epithelial cancers, and its expression correlates with a more metastatic cancer phenotype. However, normal functioning of EGFR is essential for normal epithelial cell proliferation and differentiation. The role of EGFR-dependent signaling in the development and maintenance of epithelial TJ integrity has not been studied in detail. This study demonstrates that, in polarized Madin-Darby canine kidney II cells, EGF-induced EGFR activation significantly inhibited claudin-2 expression while simultaneously inducing cellular redistribution and increased expression of claudin-1, -3, and -4. Accompanying these EGF-induced changes in claudin expression was a 3-fold increase in transepithelial resistance, a functional measure of TJs. In contrast, there were no alterations in protein expression and/or intracellular localization of other TJ-related proteins (ZO-1 and occludin) or adherens junction-associated proteins (E-cadherin and beta-catenin), suggesting that EGF regulates TJ function through selective and differential regulation of claudins.
Singh
Amar B
AB
Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232-4794, USA.
Harris
Raymond C
RC
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D022005:Adherens Junctions; D000818:Animals; D015152:Blotting, Northern; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002448:Cell Adhesion; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D062445:Claudin-1; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins; D003513:Cycloheximide / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004285:Dogs; D004848:Epithelium / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D005786:Gene Expression Regulation; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D015151:Immunoblotting; D007668:Kidney / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009369:Neoplasms / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D010641:Phenotype; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D019108:Tight Junctions; D013997:Time Factors
C568108:CLDN1 protein, human; C491875:CLDN2 protein, human; C568122:CLDN3 protein, human; C568157:CLDN4 protein, human; D062445:Claudin-1; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins; D003902:Detergents; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors; C067713:lactacystin; D017228:Hepatocyte Growth Factor; D017830:Octoxynol; D003513:Cycloheximide; D066246:ErbB Receptors; D001973:Bromodeoxyuridine; D000111:Acetylcysteine