Ordered proteolysis in anaphase inactivates Plk1 to contribute to proper mitotic exit in human cells

Abstract

We have found that key mitotic regulators show distinct patterns of degradation during exit from mitosis in human cells. Using a live-cell assay for proteolysis, we show that two of these regulators, polo-like kinase 1 (Plk1) and Aurora A, are degraded at different times after the anaphase-promoting complex/cyclosome (APC/C) switches from binding Cdc20 to Cdh1. Therefore, events in addition to the switch from Cdc20 to Cdh1 control the proteolysis of APC/CCdh1 substrates in vivo. We have identified a putative destruction box in Plk1 that is required for degradation of Plk1 in anaphase, and have examined the effect of nondegradable Plk1 on mitotic exit. Our results show that Plk1 proteolysis contributes to the inactivation of Plk1 in anaphase, and that this is required for the proper control of mitotic exit and cytokinesis. Our experiments reveal a role for APC/C-mediated proteolysis in exit from mitosis in human cells.

An ATM- and ATR-dependent checkpoint inactivates spindle assembly by targeting CEP63

“…In late anaphase, Plk1 localized to the centre of the spindle array phosphorylates a number of substrates, which function in cytokinesis (Golsteyn et al, 1995;van Yugt and Medema, 2005). Active APC/Cdh1 during anaphase promotes Plk1 degradation, which mediates cytokinesis execution (Lindon and Pines, 2004). Mitotic progression is reliant on secruin and Cyclin B destruction, however, activation of APC by Cdc20 or Cdh1 targets different mitotic factors in a timely and orderly fashion, which contributes to the progression of mitotic exit (Sullivan and Morgan, 2007;Pines, 2006).…”

“…The last APC/Cdh1 target is Aurora B at the anaphase to telophase transition, which continues into G1 of the next cell cycle (Lindon and Pines, 2004). It has been proposed that ubiquitylated Aurora B, which promotes chromosome decondensation and nuclear envelope re-assembly, is displaced from kinetochores (Ramadan et al, 2007).…”

Protein kinases controlling the onset of mitosis

“…Vol. 63,2006 Review Article Cdc5p and Plk1 localize at centrosomes in early mitosis, redistribute to the spindle and mitotic bridge at anaphase [77] and are rapidly degraded by the APC/C-Cdh1 during exit from mitosis [76,84,85]. Whereas the Cdc5p degradation motif is localized at the N-terminus, Plk1 destruction depends on a D-box that is located in the central part of the protein [86].…”

The Coordination between DNA Replication Initiation and Other Cell Cycle Events

“…It functions essentially in mitosis, regulating a variety of the mitosis events including bipolar spindle formation, chromosome segregation, centrosome maturation, CDK1 activation, APC regulation and cytokinesis execution. During mitotic exit, Plk1 is degraded by APC-cdh1 (Lindon and Pines 2004). Plk1 recognizes its substrates by consensus recognition sequences in the PBD domain and usually requires a phosphopriming by prime kinases such as CDKs and mitogen-activated protein kinase.…”