Molecular dynamics of PLK1 during mitosis.
Ontology highlight
ABSTRACT:
SUBMITTER: Schmucker S
PROVIDER: S-EPMC4905186 | biostudies-other | 2014 Apr-Jun
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Several kinases phosphorylate vimentin, the most common intermediate filament protein, in mitosis. Aurora-B and Rho-kinase regulate vimentin filament separation through the cleavage furrow-specific vimentin phosphorylation. Cdk1 also phosphorylates vimentin from prometaphase to metaphase, but its significance has remained unknown. Here we demonstrated a direct interaction between Plk1 and vimentin-Ser55 phosphorylated by Cdk1, an event that led to Plk1 activation and further vimentin phosphorylation. Plk1 phosphorylated vimentin at approximately 1 mol phosphate/mol substrate, which partly inhibited its filament forming ability, in vitro. Plk1 induced the phosphorylation of vimentin-Ser82, which was elevated from metaphase and maintained until the end of mitosis. This elevation followed the Cdk1-induced vimentin-Ser55 phosphorylation, and was impaired by Plk1 depletion. Mutational analyses revealed that Plk1-induced vimentin-Ser82 phosphorylation plays an important role in vimentin filaments segregation, coordinately with Rho-kinase and Aurora-B. Taken together, these results indicated a novel mechanism that Cdk1 regulated mitotic vimentin phosphorylation via not only a direct enzyme reaction but also Plk1 recruitment to vimentin.
| S-EPMC2171270 | biostudies-literature
Project description:PLK1 is an important regulator of mitosis whose protein levels and activity fluctuate during the cell cycle. PLK1 dynamically localizes to various mitotic structures to regulate chromosome segregation. However, the signaling pathways linking localized PLK1 activity to its protein stability remain elusive. Here, we identify the Ubiquitin-Binding Protein 2-Like (UBAP2L) that controls both the localization and the protein stability of PLK1. We demonstrate that UBAP2L is a spindle-associated protein whose depletion leads to severe mitotic defects. UBAP2L-depleted cells are characterized by increased PLK1 protein levels and abnormal PLK1 accumulation in several mitotic structures such as kinetochores, centrosomes and mitotic spindle. UBAP2L-deficient cells exit mitosis and enter the next interphase in the presence of aberrant PLK1 kinase activity. The C-terminal domain of UBAP2L mediates its function on PLK1 independently of its role in stress response signaling. Importantly, the mitotic defects of UBAP2L-depleted cells are largely rescued by chemical inhibition of PLK1. Overall, our data suggest that UBAP2L is required to fine-tune the ubiquitin-mediated PLK1 turnover during mitosis as a means to maintain genome fidelity.
| S-EPMC10240199 | biostudies-literature
Project description:For faithful chromosome segregation, the formation of stable kinetochore-microtubule attachment and its monitoring by the spindle assembly checkpoint (SAC) are coordinately regulated by mechanisms that are currently ill-defined. Here, we show that polo-like kinase 1 (Plk1), which is instrumental in forming stable kinetochore-microtubule attachments, is also involved in the maintenance of SAC activity by binding to Bub1, but not by binding to CLASP2 or CLIP-170. The effect of Plk1 on the SAC was found to be mediated through phosphorylation of Mps1, an essential kinase for the SAC, as well as through phosphorylation of the MELT repeats in Knl1. Bub1 acts as a platform for assembling other SAC components on the phosphorylated MELT repeats. We propose that Bub1-bound Plk1 is important for the maintenance of SAC activity by supporting Bub1 localization to kinetochores in prometaphase, a time when the kinetochore Mps1 level is reduced, until the formation of stable kinetochore-microtubule attachment is completed. Our study reveals an intricate mechanism for coordinating the formation of stable kinetochore-microtubule attachment and SAC activity.
| S-EPMC5562746 | biostudies-literature
Project description:Endocytic vesicle fusion is inhibited during mitosis, but the molecular pathways that mediate the inhibition remain unclear. Here we uncovered an essential role of Polo-like kinase 1 (Plk1) in this mechanism. Phosphoproteomic analysis revealed that Plk1 phosphorylates the intermediate filament protein vimentin on Ser459, which is dispensable for its filament formation but is necessary for the inhibition of endocytic vesicle fusion in mitosis. Furthermore, this mechanism is required for integrin trafficking toward the cleavage furrow during cytokinesis. Our results thus identify a novel mechanism for fusion inhibition in mitosis and implicate its role in vesicle trafficking after anaphase onset.
| S-EPMC3925722 | biostudies-literature
Project description: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.
| S-EPMC7116173 | biostudies-literature
Project description:Kv10.1 (potassium voltage-gated channel subfamily H member 1, known as EAG1 or Ether-à-go-go 1), is a voltage-gated potassium channel, prevailingly expressed in the central nervous system. The aberrant expression of Kv10.1 is detected in over 70% of all human tumor tissues and correlates with poorer prognosis. In peripheral tissues, Kv10.1 is expressed almost exclusively during the G2/M phase of the cell cycle and regulates its progression-downregulation of Kv10.1 extends the duration of the G2/M phase both in cancer and healthy cells. Here, using biochemical and imaging techniques, such as live-cell measurements of microtubule growth and of cytosolic calcium, we elucidate the mechanisms of Kv10.1-mediated regulation at the G2/M phase. We show that Kv10.1 has a dual effect on mitotic microtubule dynamics. Through the functional interaction with ORAI1 (calcium release-activated calcium channel protein 1), it modulates cytosolic calcium oscillations, thereby changing microtubule behavior. The inhibition of either Kv10.1 or ORAI1 stabilizes the microtubules. In contrast, the knockdown of Kv10.1 increases the dynamicity of mitotic microtubules, resulting in a stronger spindle assembly checkpoint, greater mitotic spindle angle, and a decrease in lagging chromosomes. Understanding of Kv10.1-mediated modulation of the microtubule architecture will help to comprehend how cancer tissue benefits from the presence of Kv10.1, and thereby increase the efficacy and safety of Kv10.1-directed therapeutic strategies.
| S-EPMC7564071 | biostudies-literature
Project description:Caspase-8 is crucial for cell death induction, especially via the death receptor pathway. The dysregulated expression or function of caspase-8 can promote tumor formation, progression and treatment resistance in different human cancers. Here, we show procaspase-8 is regulated during the cell cycle through the concerted inhibitory action of Cdk1/cyclin B1 and polo-like kinase 1 (Plk1). By phosphorylating S387 in procaspase-8 Cdk1/cyclin B1 generates a phospho-epitope for the binding of the PBD of Plk1. Subsequently, S305 in procaspase-8 is phosphorylated by Plk1 during mitosis. Using an RNAi-based strategy we could demonstrate that the extrinsic cell death is increased upon Fas-stimulation when endogenous caspase-8 is replaced by a mutant (S305A) mimicking the non-phosphorylated form. Together, our data show that sequential phosphorylation by Cdk1/cyclin B1 and Plk1 decreases the sensitivity of cells toward stimuli of the extrinsic pathway during mitosis. Thus, the clinical Plk1 inhibitor BI 2536 decreases the threshold of different cancer cell types toward Fas-induced cell death.
| S-EPMC5528627 | biostudies-literature
Project description:Features of higher-order chromatin organization-such as A/B compartments, topologically associating domains and chromatin loops-are temporarily disrupted during mitosis1,2. Because these structures are thought to influence gene regulation, it is important to understand how they are re-established after mitosis. Here we examine the dynamics of chromosome reorganization by Hi-C after mitosis in highly purified, synchronous mouse erythroid cell populations. We observed rapid establishment of A/B compartments, followed by their gradual intensification and expansion. Contact domains form from the 'bottom up'-smaller subTADs are formed initially, followed by convergence into multi-domain TAD structures. CTCF is partially retained on mitotic chromosomes and immediately resumes full binding in ana/telophase. By contrast, cohesin is completely evicted from mitotic chromosomes and regains focal binding at a slower rate. The formation of CTCF/cohesin co-anchored structural loops follows the kinetics of cohesin positioning. Stripe-shaped contact patterns-anchored by CTCF-grow in length, which is consistent with a loop-extrusion process after mitosis. Interactions between cis-regulatory elements can form rapidly, with rates exceeding those of CTCF/cohesin-anchored contacts. Notably, we identified a group of rapidly emerging transient contacts between cis-regulatory elements in ana/telophase that are dissolved upon G1 entry, co-incident with the establishment of inner boundaries or nearby interfering chromatin loops. We also describe the relationship between transcription reactivation and architectural features. Our findings indicate that distinct but mutually influential forces drive post-mitotic chromatin reconfiguration.
| S-EPMC6895436 | biostudies-literature
Project description:Microtubule-based motor proteins play key roles during mitosis to assemble the bipolar spindle, define the cell division axis, and align and segregate the chromosomes. The majority of mitotic motors are members of the kinesin superfamily. Despite sharing a conserved catalytic core, each kinesin has distinct functions and localization, and is uniquely regulated in time and space. These distinct behaviors and functional specificity are generated by variations in the enzymatic domain as well as the non-conserved regions outside of the kinesin motor domain and the stalk. These flanking regions can directly modulate the properties of the kinesin motor through dimerization or self-interactions, and can associate with extrinsic factors, such as microtubule or DNA binding proteins, to provide additional functional properties. This review discusses the recently identified molecular mechanisms that explain how the control and functional specification of mitotic kinesins is achieved.
| S-EPMC4065354 | biostudies-literature
Project description:DNA double-strand breaks (DSBs) are deleterious lesions that challenge genome integrity. To mitigate this threat, human cells rely on the activity of multiple DNA repair machineries that are tightly regulated throughout the cell cycle1. In interphase, DSBs are mainly repaired by non-homologous end joining and homologous recombination2. However, these pathways are completely inhibited in mitosis3-5, leaving the fate of mitotic DSBs unknown. Here we show that DNA polymerase theta6 (Polθ) repairs mitotic DSBs and thereby maintains genome integrity. In contrast to other DSB repair factors, Polθ function is activated in mitosis upon phosphorylation by Polo-like kinase 1 (PLK1). Phosphorylated Polθ is recruited by a direct interaction with the BRCA1 C-terminal domains of TOPBP1 to mitotic DSBs, where it mediates joining of broken DNA ends. Loss of Polθ leads to defective repair of mitotic DSBs, resulting in a loss of genome integrity. This is further exacerbated in cells that are deficient in homologous recombination, where loss of mitotic DSB repair by Polθ results in cell death. Our results identify mitotic DSB repair as the underlying cause of synthetic lethality between Polθ and homologous recombination. Together, our findings reveal the critical importance of mitotic DSB repair in the maintenance of genome integrity.
| S-EPMC10499603 | biostudies-literature