Differential regulation of junctional complex assembly in renal epithelial cell lines

• Published in: American Journal of Physiology: Cell Physiology Vol. 285; no. 1; pp. C102 - C111
• Main Authors: Gopalakrishnan, Shobha, Hallett, Mark A, Atkinson, Simon J, Marrs, James. A
• Format: Journal Article
• Language: English
• Published: United States 01.07.2003
• Subjects: 3T3 Cells; Adherens Junctions - physiology; Animals; Cysteine Proteinase Inhibitors - pharmacology; Dipeptides - pharmacology; Down-Regulation - drug effects; Epithelial Cells - physiology; Kidney - cytology; LLC-PK1 Cells; Membrane Proteins - metabolism; Mice; Occludin; Phosphoproteins - metabolism; rho GTP-Binding Proteins - metabolism; Signal Transduction - physiology; Stress Fibers - drug effects; Stress Fibers - enzymology; Swine; Tight Junctions - physiology; Zonula Occludens-1 Protein
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00583.2002

Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana 46202-5181 Submitted 16 December 2002 ; accepted in final form 3 March 2003 Several signaling pathways that regulate tight junction and adherens junction assembly are being characterized. Calpeptin activates stress fiber assembly in fibroblasts by inhibiting SH2-containing phosphatase-2 (SHP-2), thereby activating Rho-GTPase signaling. Here, we have examined the effects of calpeptin on stress fiber and junctional complex assembly in Madin-Darby canine kidney (MDCK) and LLC-PK epithelial cells. Calpeptin induced disassembly of stress fibers and inhibition of Rho GTPase activity in MDCK cells. Interestingly, calpeptin augmented stress fiber formation in LLC-PK epithelial cells. Calpeptin treatment of MDCK cells resulted in a displacement of zonula occludens-1 (ZO-1) and occludin from cell-cell junctions and a loss of phosphotyrosine on ZO-1 and ZO-2, without any detectable effect on tight junction permeability. Surprisingly, calpeptin increased paracellular permeability in LLC-PK cells even though it did not affect tight junction assembly. Calpeptin also modulated adherens junction assembly in MDCK cells but not in LLC-PK cells. Calpeptin treatment of MDCK cells induced redistribution of E-cadherin and -catenin from intercellular junctions and reduced the association of p120ctn with the E-cadherin/catenin complex. Together, our studies demonstrate that calpeptin differentially regulates stress fiber and junctional complex assembly in MDCK and LLC-PK epithelial cells, indicating that these pathways may be regulated in a cell line-specific manner. calpeptin; tight junctions; adherens junctions; Rho; cadherin; p120ctn Address for reprint requests and other correspondence: J. A. Marrs, Dept. of Medicine, Div. of Nephrology, Indiana Univ. Medical Center, R2 223, 950 West Walnut St., Indianapolis, IN 46202-5181 (E-mail: jmarrs{at}iupui.edu ).