Dystroglycan receptor is involved in integrin activation in intestinal epithelia

Abstract

The dystroglycans (α-DG and β-DG), which play important roles in the formation of basement membranes, have been well studied in skeletal muscle and nerve, but their expression and localization in intestinal epithelial cells has not been previously investigated. Here, we demonstrated that the DG complex, composed of α-DG, β-DG, and utrophin, is specifically expressed in the basolateral membrane of the Caco-2-BBE monolayer. The DG complex coprecipitated with β1-integrin, suggesting a possible interaction among these proteins. In addition, we observed that activation of DG receptors by laminin-1 enhanced the interaction between β1-integrin and laminin-1, whereas activation of DG receptors by laminin-2 reduced the interaction between β1-integrin and laminin-2. Finally, we demonstrated that the intracellular COOH-terminal tail of β-DG and its binding to the DG binding domain of utrophin are crucial for the interactions between laminin-1/-2 and β1-integrin. Collectively, these novel results indicate that dystroglycans play important roles in the regulation of interactions between intestinal epithelial cells and the extracellular matrix.