The plakoglobin knock-out mouse: a paradigm for the molecular analysis of cardiac cell junction formation

Plakoglobin (γ-catenin), a member of the armadillo family of proteins, is a constituent of the cytoplasmic plaques of desmosomes and adherens junctions and is involved in anchorage of cytoskeletal filaments to specific cadherins. When the plakoglobin gene is ablated in mice, animals die between days 12 and 16 of embryogenesis owing to defects in heart function. Often, their heart ventricles burst, and pericardial tamponade appears to be the immediate cause of death. This tissue instability correlates with the absence of desmosomes and a redistribution of desmosomal proteins in heart, but not in epithelial organs. Plakoglobin is an essential component of cardiac desmosomes and plays a crucial role in the architecture and stabilization of heart tissue.