Spatiotemporal control of mitotic exit during anaphase by an aurora B-Cdk1 crosstalk.

Afonso, Olga; Castellani, Colleen M; Cheeseman, Liam P; Ferreira, Jorge G; Orr, Bernardo; Ferreira, Luisa T; Chambers, James J; Morais-de-Sá, Eurico et al. · Elife · 2019

basic_science · Level V

Where this comes from

Abstract

According to the prevailing 'clock' model, chromosome decondensation and nuclear envelope reformation when cells exit mitosis are byproducts of Cdk1 inactivation at the metaphase-anaphase transition, controlled by the spindle assembly checkpoint. However, mitotic exit was recently shown to be a function of chromosome separation during anaphase, assisted by a midzone Aurora B phosphorylation gradient - the 'ruler' model. Here we found that Cdk1 remains active during anaphase due to ongoing APC/C<sup>Cdc20</sup>- and APC/C<sup>Cdh1</sup>-mediated degradation of B-type Cyclins in <i>Drosophila</i> and human cells. Failure to degrade B-type Cyclins during anaphase prevented mitotic exit in a Cdk1-dependent manner. Cyclin B1-Cdk1 localized at the spindle midzone in an Aurora B-dependent manner, with incompletely separated chromosomes showing the highest Cdk1 activity. Slowing down anaphase chromosome motion delayed Cyclin B1 degradation and mitotic exit in an Aurora B-dependent manner. Thus, a crosstalk between molecular 'rulers' and 'clocks' licenses mitotic exit only after proper chromosome separation.

Medical subject headings