Ubiquitylation-dependent localization of PLK1 in mitosis

Abstract

Polo-like kinase 1 (PLK1) critically regulates mitosis through its dynamic localization to kinetochores, centrosomes and the midzone. The polo-box domain (PBD) and activity of PLK1 mediate its recruitment to mitotic structures, but the mechanisms regulating PLK1 dynamics remain poorly understood. Here, we identify PLK1 as a target of the cullin 3 (CUL3)-based E3 ubiquitin ligase, containing the BTB adaptor KLHL22, which regulates chromosome alignment and PLK1 kinetochore localization but not PLK1 stability. In the absence of KLHL22, PLK1 accumulates on kinetochores, resulting in activation of the spindle assembly checkpoint (SAC). CUL3-KLHL22 ubiquitylates Lys 492, located within the PBD, leading to PLK1 dissociation from kinetochore phosphoreceptors. Expression of a non-ubiquitylatable PLK1-K492R mutant phenocopies inactivation of CUL3-KLHL22. KLHL22 associates with the mitotic spindle and its interaction with PLK1 increases on chromosome bi-orientation. Our data suggest that CUL3-KLHL22-mediated ubiquitylation signals degradation-independent removal of PLK1 from kinetochores and SAC satisfaction, which are required for faithful mitosis.

Using in Vivo Biotinylated Ubiquitin to Describe a Mitotic Exit Ubiquitome from Human Cells

“…Given these facts, it is perhaps surprising that the APC/C is almost the only known engineer of the protein landscape after anaphase onset, targeting mitotic regulators for destruction with high temporal specificity (2)(3)(4). Some roles for nondegradative ubiquitination in regulating the localization of mitotic kinases Aurora B and Plk1 have been described (5)(6)(7)(8)(9), and a growing list of reported ubiquitin interactors can modulate ubiquitin-dependent events during mitosis (10). However, the majority of ubiquitination events that have so far been described as occurring at the transition from mitosis to interphase are APC/C-dependent.…”

The condensin component NCAPG2 regulates microtubule–kinetochore attachment through recruitment of Polo-like kinase 1 to kinetochores

“…Other proteins may be involved in PLK1 localization and delocalization to the kinetochore; PBIP1, BUB1, NUDC, INCENP and CUL3-KLHL22 may contribute cooperatively with or independent of NCAPG2 (refs [40][41][42]46,47). However, considering the depletion phenotypes, NCAPG2 plays the most critical role in the kinetochore-microtubule interaction governed by PLK1 during prometaphase to metaphase 40,41,[46][47][48] .…”

“…However, considering the depletion phenotypes, NCAPG2 plays the most critical role in the kinetochore-microtubule interaction governed by PLK1 during prometaphase to metaphase 40,41,[46][47][48] . Taken together, NCAPG2 contributes to PLK1 kinetochore localization for the kinetochore-microtubule interaction, and CUL3-KLHL22 delocalizes PLK1 from the kinetochore after BubR1 phosphorylation 47 . These results suggest that PLK1 localization …”

“…to the kinetochore is governed by different proteins and depends on the timeline of mitosis progression 40,47 . NCAPG2-regulated PLK1 localization occurs during the initial stage of the microtubule-kinetochore interaction because the NCAPG2 and PLK1 interactions primarily occur during prometaphase, before chromosome alignment is completed.…”

Cdk1 plays matchmaker for the Polo-like kinase and its activator SPAT-1/Bora

“…16 Interaction of the PBD with its targets can also be regulated by ubiquitination of the PBD. 17 The PBD is thus a protein-protein interaction module capable of various types of interactions.…”