Clathrin-mediated endocytic proteins are involved in regulating mitotic progression and completion.

A few proteins required for clathrin-mediated endocytosis (CME) are associated with successful completion of mitosis at distinct mitotic stages. Clathrin heavy chain (CHC) and epsin are required for chromosome segregation independent of their CME function and dynamin II (dynII) functions in the abscission stage of cytokinesis. In this study we screened for mitotic roles of eight CME proteins: CHC, α-adaptin, CALM, epsin, eps15, endophilin II (edpnII), syndapin II (sdpnII) and the GTPase dynII using a small interfering RNA targeting approach. All proteins, except for CALM, are associated with completion of the abscission stage of cytokinesis, suggesting that they function in this process in an endocytic-dependent manner. In support of this concept, overexpression of epsin(S357D), which blocks endocytosis, induced multinucleation. Moreover, six of them have a secondary role at earlier mitotic stages that is not dependent on their endocytic function: CHC, epsin and eps15 in chromosome segregation, and sdpnII, α-adaptin and CALM have a role in furrow ingression. Therefore, the role of endocytic proteins in mitosis is much broader than previously recognized.