PP2A-Tws dephosphorylates Map205, is required for Polo localization to microtubules and promotes cytokinesis in Drosophila.

Abstract

Background: Mitosis and cytokinesis are regulated by reversible phosphorylation events controlled by kinases and phosphatases. Drosophila Polo kinase, like its human ortholog PLK1, plays several roles in this process. Multiple mechanisms contribute to regulate Polo/PLK1 activity, localization and interactions. We previously showed that the microtubule-associated protein Map205 interacts with Polo during interphase and cytokinesis, inhibiting and sequestering Polo on microtubules. During mitosis, phosphorylation of Map205 at a Cyclin-Dependent Kinase site allows Polo to dissociate from Map205, when Polo must fulfill its mitotic functions. How the Polo/Map205 interaction is restored during mitotic exit remained unknown.

Results: Here we show that PP2A-Tws/B55 is required to dephosphorylate Map205, and enables the Map205-dependent localization of Polo to microtubules during cytokinesis. In addition, we show that PP2A-Tws is required for spindle function during cytokinesis, consistent with the essential role of Polo in this process.

Conclusions: These findings complement previous studies to provide an understanding of the full cycle of Polo regulation by Map205, kinases and phosphatases. Our findings have implications for the wider network of cell cycle regulatory circuitry.