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bioRxiv · 10.1101/2020.11.27.400903

PP2A-Cdc55 phosphatase coordinates actomyosin ring contraction and septum formation during cytokinesis

Moyano-Rodriguez, Y.·Vilalta-Castany, O.·Foltman, M.·Sanchez-Diaz, A.·Queralt, E.
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Abstract

Eukaryotic cells divide and separate all their components after chromosome segregation by a process called cytokinesis to complete cell division. Cytokinesis is highly regulated by recruitment of the components to the division site and through post-translational modifications such as phosphorylations. The budding yeast mitotic kinases Cdc28-Clb2, Cdc5, and Dbf2-Mob1 phosphorylate several cytokinetic proteins contributing to the regulation of cytokinesis. The PP2A-Cdc55 phosphatase regulates mitosis counteracting Cdk1- and Cdc5-dependent phosphorylation. This prompted us to propose that PP2A-Cdc55 could also be counteracting the mitotic kinases during cytokinesis. Here, we demonstrate that primary septum formation and actomyosin ring contraction are impaired in the absence of PP2A-Cdc55. In addition, by in vivo and in vitro assays, we show that PP2A-Cdc55 dephosphorylates the chitin synthase II (Chs2 in budding yeast) a component of the Ingression Progression Complexes (IPCs) involved in cytokinesis. Interestingly, the non-phosphorylable version of Chs2 rescues the asymmetric AMR contraction observed in cdc55{Delta} mutant cells. Therefore, timely dephosphorylation of the Chs2 by PP2A-Cdc55 is crucial for proper actomyosin ring contraction. These findings reveal a new mechanism of cytokinesis regulation by the PP2A-Cdc55 phosphatase and extend our knowledge in the involvement of multiple phosphatases during cytokinesis.

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Moyano-Rodriguez, Y., Vilalta-Castany, O., Foltman, M., Sanchez-Diaz, A., Queralt, E.. 2020-11-27. PP2A-Cdc55 phosphatase coordinates actomyosin ring contraction and septum formation during cytokinesis. https://doi.org/10.1101/2020.11.27.400903

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