Proteolytic processing of the adherens junctions components β-catenin and γ-catenin/plakoglobin during apoptosis

Abstract

Apoptotic cells undergo specific morphological changes that include loss of cell-cell interactions. Cellular adhesiveness is dependent on members of the cadherin family of adhesion receptors and on the cytoplasmic adaptor proteins α-catenin, β-catenin and γ-catenin/plakoglobin. The caspase family of cystein proteases play a key role during the execution phase of the apoptotic program. These proteolytic enzymes, once activated, cleave cellular proteins which are important for the maintenance of cell integrity. Here we report that γ-catenin is cleaved at different sites during apoptosis in various cell lines. The major apoptotic product of γ-catenin still retains the ability to bind α-catenin but loses the carboxy-terminal region. We also show that γ-catenin is cleaved by caspase-3 in vitro although with lower affinity when compared to PARP or β-catenin. These findings indicate that multiple proteolytic events regulate the dismantling of the cell-cell junctional complexes during apoptosis.