LAUSR

Apoptotic extrusion is a process, where junctional contractility is spatially regulated at a supracellular scale to expel a dying cell from the epithelial sheet. During apoptotic extrusion, E-cadherin based cell coupling transduces forces from the constricting actomyosin cable through the apoptotic cell interface. Since epithelial turnover is very prevalent in intestine and other simple epithelia, we wanted to address the consequence of apoptotic extrusion on the other intercellular adhesion, the desmosome. In this study, the dynamics of the neighboring tissue during extrusion is studied by subjecting cells to an ultraviolet laser based apoptotic stimulus. We show that desmosome exhibits dynamics and retains its junctional presence during extrusion. The intensity of the junctional desmoglein-2 increased during the constriction phase of extrusion. Depletion of desmoplakin by RNA interference resulted in constriction defects, indicating its importance in facilitating extrusion. A concomitant recruitment of cytokeratin-18 filaments to the apoptotic cell interface was observed during constriction. The recruited keratin filaments were proximate to the actomyosin cable at the interface. We further show evidence that cytokeratin-18 and desmosome influence junctional contractility in steady state and extruding junctions.