The S. pombe cytokinesis NDR kinase Sid2 activates Fin1 NIMA kinase to control mitotic commitment th

Abstract

In fission yeast, the septum initiation network (SIN) regulates septation at the end of mitosis. Hagan and colleagues now reveal a further role for the SIN kinase Sid2 that is independent of other known SIN components, in the control of entry into mitosis through phosphorylation of the NIMA kinase Fin1. Mitotic exit integrates the reversal of the phosphorylation events initiated by mitotic kinases with a controlled cytokinesis event that cleaves the cell in two. The mitotic exit network (MEN) of budding yeast regulates both processes, whereas the fission yeast equivalent, the septum initiation network (SIN), controls only the execution of cytokinesis. The components and architecture of the SIN and MEN are highly conserved1. At present, it is assumed that the functions of the core SIN–MEN components are restricted to their characterized roles at the end of mitosis. We now show that the NDR (nuclear Dbf2-related) kinase component of the fission yeast SIN, Sid2–Mob1, acts independently of the other known SIN components in G2 phase of the cell cycle to control the timing of mitotic commitment. Sid2–Mob1 promotes mitotic commitment by directly activating the NIMA (Never In Mitosis)-related kinase Fin1. Fin1’s activation promotes its own destruction, thereby making Fin1 activation a transient feature of G2 phase. This spike of Fin1 activation modulates the activity of the Pom1/Cdr1/Cdr2 geometry network towards Wee1.

Cite this article

Grallert, A., Connolly, Y., Smith, D. et al. The S. pombe cytokinesis NDR kinase Sid2 activates Fin1 NIMA kinase to control mitotic commitment through Pom1/Wee1. Nat Cell Biol 14, 738–745 (2012). https://doi.org/10.1038/ncb2514

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