Multiple roles of the furrow deepening Ca2+ transient during cytokinesis in zebrafish embryos

The generation of a required series of localized Ca2+ transients during cytokinesis in zebrafish embryos suggests that Ca2+ plays a necessary role in regulating this process. Here, we report that cortical actin remodeling, characterized by the reorganization of the contractile band and the formation during furrow deepening of pericleavage F-actin enrichments (PAEs), requires a localized increase in intracellular Ca2+, which is released from IP3-sensitive stores. We demonstrate that VAMP-2 vesicle fusion at the deepening furrow also requires Ca2+ released via IP3 receptors, as well as the presence of PAEs and the action of calpains. Finally, by expressing a dominant-negative form of the kinesin-like protein, kif23, we demonstrate that its recruitment to the furrow region is required for VAMP-2 vesicle transport; and via FRAP analysis, that kif23 localization is also Ca2+-dependent. Collectively, our data demonstrate that a localized increase in intracellular Ca2+ is involved in regulating several key events during furrow deepening and subsequent apposition.