Cytokinesis and the evolution of Metazoa [EXTRAORDINARY IRB Research Nodes Seminar]

Animal cells use the anaphase spindle as a spatial cue to position the division plane. The centralspindlin complex, accumulates at the spindle midzone and promotes Rho1 activation, which is both necessary and sufficient for division plane positioning. Centralspindlin/Ect2 sustains Rho1 activity throughout the furrowing process. The linkage of the division plane to the spindle midzone not only prevents aneuploidy, but it also enables regulated spindle displacements to result in asymmetric cell division and enables the division of cells of vastly different sizes, as the mitotic spindle scales with cell size. Following ingression, centralspindlin nucleates an intercellular bridge that physically connects daughter cells. Many, but not all, cells eventually sever this bridge and undergo abscission, generating separate daughter cells. Phylogenetic analysis reveals that Centralspindlin/Ect2 emerged coincident with the emergence of Metazoa. In my talk I will discuss our current understanding of the function and regulation of centralspindlin/Ect2 and the evidence that it played a direct role in the evolution of animal multicellularity.