Separase Regulates INCENP-Aurora B Anaphase Spindle Function Through Cdc14

Abstract

The inner centromere-like protein (INCENP) forms a complex with the evolutionarily conserved family of Aurora Bkinases. The INCENP-Aurora complex helps coordinate chromosome segregation, spindle behavior, and cytokinesis during mitosis. INCENP-Aurora associates with kinetochores in metaphase and with spindle microtubules in anaphase, yet the trigger for this abrupt transfer is unknown. Here we show that the conserved phosphatase Cdc14 regulated the yeast INCENP-Aurora complex, Sli15-Ipl1. Cdc14 dephosphorylated Sli15 and thereby directed the complex to spindles. Activation of Cdc14 by separase was sufficient for Sli15 dephosphorylation and relocalization. Cdc14 not only regulates mitotic exit but also modulates spindle midzone assembly through Sli15-Ipl1.

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and Cytokinesis

“…Our results agree with previous studies showing a role for the chromosomal passenger protein complex in the stability of the mitotic spindle in yeast (Buvelot et al, 2003;Pereira and Schiebel, 2003). In vertebrate systems, the chromosomal passenger protein complex regulates the localization and activity of MCAK, a microtubule-depolymerizing protein crucial for spindle assembly (Lan et al, 2004;Sampath et al, 2004).…”

Cell cycle control of spindle elongation

“…7,27,60,[79][80][81] Accordingly, several proteins involved in spindle assembly and regulation of MT dynamics have been uncovered as targets of this regulatory scheme. 60,69,[82][83][84] Whereas the majority of these substrates have only been identified in a subset of organisms, phosphorylation of the central midzone marker Ase1/PRC1 by Cdk1 in metaphase and reversal of these modifications in anaphase seems to be conserved among all model systems. 72,[85][86][87][88] …”

Centromere Targeting of the Chromosomal Passenger Complex Requires a Ternary Subcomplex of Borealin, Survivin, and the N-Terminal Domain of INCENP

“…For chicken INCENP, it has been demonstrated that amino acids 1-68 are sufficient to direct the protein to centromeres (Ainsztein et al, 1998). In budding yeast, the removal of cyclin-dependent kinase (Cdk)1 phosphorylation sites from INCENP seems to be important for the transfer of INCENP from the centromere to the central spindle, raising the possibility that Cdk1 phosphorylation might play a role in the centromere targeting of INCENP (Pereira and Schiebel, 2003). Sequence analysis of the first 68 amino acids of human INCENP indicated the presence of a conserved Cdk1-consensus site at position T59 and an in vitro kinase assay showed that T59 is the only Cdk phosphorylation site within INCENP 1-68 (our unpublished data).…”

“…In budding yeast, the dephosphorylation of INCENP by the Cdc14 phosphatase has been shown to be important for the transfer of INCENP from the centromere to the central spindle (Pereira and Schiebel, 2003), and this might be an additional form of regulation in human cells, too (Gruneberg et al, 2004). However, how the CPC proteins target to the centromere in the first place is unclear.…”