Elucidating the role of AAA-ATPase VPS4 in cytokinetic abscission

The ESCRT machinery (composed of 5 subfamilies: ESCRT-0, I, II, III and VPS4) drives membrane constriction and remodeling among variety of biological processes including viral budding, multivesicular body (MVB) formation and cytokinetic abscission. Each process has a specific membrane geometry and scale (~ 50nm - 1µm) indicating that the ESCRT machinery is an adaptable machine that can modulate itself to fit specific process demands. Among the ESCRT subfamilies, ESCRT-III and VPS4 are thought to be the driving force for membrane fission. According to the current model, ESCRT-III self-polymerizes into helical filaments on the membrane, while VPS4 remodels or/and disassemble these filaments in an ATP dependent manner. Mammalian VPS4 possess two isoforms: VPS4A and VPS4B. Currently, it is unknown whether these isoforms functions independently from each other or cooperate to facilitated membrane scission. To study the role of the VPS4 isoforms in cytokinetic abscission we generated VPS4A and VPS4B knockout cell lines and characterized abscission in these cells using a toolbox of high-resolution microscopy tools, previously used to characterized abscission in naïve cells. By comparing the similarities and differences of the spatiotemporal characteristics of abscission and of ESCRTs in abscission we aim to elucidate the role of these isoforms. As VPS4, is the only energy source in the ESCRT pathway, understanding its way of action is crucial for unlocking the mechanism by which the ESCRT machine remodels and cut membrane.