EphA2 Phosphorylates the Cytoplasmic Tail of Claudin-4 and Mediates Paracellular Permeability

Masamitsu Tanaka,Reiko Kamata,Ryuichi Sakai

doi:10.1074/jbc.m503786200

Abstract

Eph receptors and ephrin ligands are widely expressed in epithelial cells and mediate cell-cell interaction. EphA2 is expressed in various cancer tissues and cell lines. Although the mechanism of action of EphA2 is unknown, its expression correlates with progression of the malignant phenotype of cancerous tissues. Here, we have shown that EphA2 modulates the localization and function of claudin-4, a constituent of tight junctions. EphA2 associates with claudin-4 via their extracellular domains. This association, in turn, leads to phosphorylation of the cytoplasmic carboxyl terminus of claudin-4 at Tyr-208. The tyrosine phosphorylation of claudin-4 attenuates association of claudin-4 with ZO-1, decreasing integration of claudin-4 into sites of cell-cell contact and enhancing paracellular permeability. These results indicate that EphA2 moderates the function of tight junctions via phosphorylation of claudin-4.

Highlights

In this study, we have described the biological interaction of EphA2 with claudin-4
Analysis of paracellular flux indicated that activation of EphA2 delayed assembly of tight junctions in Madin-Darby canine kidney (MDCK)2 cells, and this depended on EphA2 kinase activity
The studies of Eph receptors and ephrins have focused on their neuronal targeting and neural plasticity [5,6,7,8,9], they are widely expressed in epithelial cells, and overexpression of Eph receptors and ephrins has been reported in various tumors

Summary

Introduction

Upon cell-cell contact, a tyrosine residue located in the carboxyl-terminal region of claudin-4 was phosphorylated by activated EphA2. EphA2 coprecipitated with claudin-4 immunoprecipitated with claudin-4-specific antibodies (Fig. 1a, left panel). Claudin-4 binds to EphA2-(⌬207–540), which contains the core region necessary for the interaction with its cognate ligand, ephrin-A1 (Fig. 2b, right panel).

Results

Conclusion