Institute for Research in Immunology and Cancer - University of Montreal 

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Host:  Jorgen Johansen

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"Cell cycle regulation by the Greatwall-PP2A axis in Drosophila"

Cell division in eukaryotes is driven largely by cyclical phosphorylation events. In mitosis, phosphorylation of several proteins by kinases induces chromosome condensation, nuclear envelope breakdown and microtubule spindle assembly. Dephosphorylation of these proteins by phosphatases allows the return to interphase after mitosis. While several kinases are activated for mitotic entry and inhibited for mitotic exit, competing phosphatases are inhibited at mitotic entry and reactivated during mitotic exit.

In the last 15 years, work in Drosophila and Xenopus has uncovered a crucial mechanism that ensures coordination between the mitotic kinase CDK1 and its main competing phosphatase PP2A-B55/Twins. I will present our work aimed at understanding the spatiotemporal regulation of this mechanism, which involves Greatwall and Endosulfine, in the dividing cell. I will also present the role of PP2A-Twins in the reformation of the nuclear envelope after mitosis in Drosophila.