TRF1 Ensures the Centromeric Function of Aurora-B and Proper Chromosome Segregation

Abstract The nucleolus is a membrane-less nuclear structure that disassembles when cells undergo mitosis. During mitosis, nucleolar factors are thus released from the nucleolus and dynamically change their subcellular localization; however, their functions remain largely uncharacterised. Here, we found that a nucleolar factor called nucleolar protein 11 (NOL11) forms a protein complex with two tryptophan-aspartic acid (WD) repeat proteins named WD-repeat protein 43 (WDR43) and Cirhin in mitotic cells. This complex, referred to here as the NWC (NOL11-WDR43-Cirhin) complex, exists in nucleoli during interphase and translocates to the periphery of mitotic chromosomes, i.e., perichromosomal regions. During mitotic progression, both the congression of chromosomes to the metaphase plate and sister chromatid cohesion are impaired in the absence of the NWC complex, as it is required for the centromeric enrichment of Aurora B and the associating phosphorylation of histone H3 at threonine 3. These results reveal the characteristics of a novel protein complex consisting of nucleolar proteins, which is required for regulating kinetochores and centromeres to ensure faithful chromosome segregation.

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Mechanism of Aurora-B Degradation and Its Dependency on Intact KEN and A-Boxes: Identification of an Aneuploidy-Promoting Property

Molecular and Cellular Biology ◽

10.1128/mcb.25.12.4977-4992.2005 ◽

2005 ◽

Vol 25 (12) ◽

pp. 4977-4992 ◽

Cited By ~ 100

Author(s):

Hao G. Nguyen ◽

Dharmaraj Chinnappan ◽

Takeshi Urano ◽

Katya Ravid

Keyword(s):

Chromosome Segregation ◽

Fluorescent Protein ◽

Point Mutations ◽

Degradation Pathway ◽

Aurora B ◽

Stable Form ◽

Wild Type ◽

Green Fluorescent ◽

Critical Regions

ABSTRACT The kinase Aurora-B, a regulator of chromosome segregation and cytokinesis, is highly expressed in a variety of tumors. During the cell cycle, the level of this protein is tightly controlled, and its deregulated abundance is suspected to contribute to aneuploidy. Here, we provide evidence that Aurora-B is a short-lived protein degraded by the proteasome via the anaphase-promoting cyclosome complex (APC/c) pathway. Aurora-B interacts with the APC/c through the Cdc27 subunit, Aurora-B is ubiquitinated, and its level is increased upon treatment with inhibitors of the proteasome. Aurora-B binds in vivo to the degradation-targeting proteins Cdh1 and Cdc20, the overexpression of which accelerates Aurora-B degradation. Using deletions or point mutations of the five putative degradation signals in Aurora-B, we show that degradation of this protein does not depend on its D-boxes (RXXL), but it does require intact KEN boxes and A-boxes (QRVL) located within the first 65 amino acids. Cells transfected with wild-type or A-box-mutated or KEN box-mutated Aurora-B fused to green fluorescent protein display the protein localized to the chromosomes and then to the midzone during mitosis, but the mutated forms are detected at greater intensities. Hence, we identified the degradation pathway for Aurora-B as well as critical regions for its clearance. Intriguingly, overexpression of a stable form of Aurora-B alone induces aneuploidy and anchorage-independent growth.

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Survivin regulates chromosome segregation by modulating the phosphorylation of Aurora B during porcine oocyte meiosis

Cell Cycle ◽

10.1080/15384101.2018.1542894 ◽

2018 ◽

Vol 17 (21-22) ◽

pp. 2436-2446 ◽

Cited By ~ 2

Author(s):

Li Chen ◽

Tailang Yin ◽

Zheng-Wen Nie ◽

Tao Wang ◽

Ying-Ying Gao ◽

...

Keyword(s):

Chromosome Segregation ◽

Aurora B ◽

Oocyte Meiosis ◽

Porcine Oocyte

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Differential requirement for Bub1 and Bub3 in regulation of meiotic versus mitotic chromosome segregation

The Journal of Cell Biology ◽

10.1083/jcb.201909136 ◽

2020 ◽

Vol 219 (4) ◽

Cited By ~ 2

Author(s):

Gisela Cairo ◽

Anne M. MacKenzie ◽

Soni Lacefield

Keyword(s):

Chromosome Segregation ◽

Protein Phosphatase ◽

Mitotic Chromosome ◽

Budding Yeast ◽

Meiotic Chromosome ◽

Protein Phosphatase 1 ◽

Aurora B ◽

Chromosome Missegregation ◽

Anaphase Onset ◽

Spindle Microtubules

Accurate chromosome segregation depends on the proper attachment of kinetochores to spindle microtubules before anaphase onset. The Ipl1/Aurora B kinase corrects improper attachments by phosphorylating kinetochore components and so releasing aberrant kinetochore–microtubule interactions. The localization of Ipl1 to kinetochores in budding yeast depends upon multiple pathways, including the Bub1–Bub3 pathway. We show here that in meiosis, Bub3 is crucial for correction of attachment errors. Depletion of Bub3 results in reduced levels of kinetochore-localized Ipl1 and concomitant massive chromosome missegregation caused by incorrect chromosome–spindle attachments. Depletion of Bub3 also results in shorter metaphase I and metaphase II due to premature localization of protein phosphatase 1 (PP1) to kinetochores, which antagonizes Ipl1-mediated phosphorylation. We propose a new role for the Bub1–Bub3 pathway in maintaining the balance between kinetochore localization of Ipl1 and PP1, a balance that is essential for accurate meiotic chromosome segregation and timely anaphase onset.

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Aurora B kinase activity is regulated by SET/TAF1 on Sgo2 at the inner centromere

The Journal of Cell Biology ◽

10.1083/jcb.201811060 ◽

2019 ◽

Vol 218 (10) ◽

pp. 3223-3236 ◽

Cited By ~ 4

Author(s):

Yuichiro Asai ◽

Koh Fukuchi ◽

Yuji Tanno ◽

Saki Koitabashi-Kiyozuka ◽

Tatsuyuki Kiyozuka ◽

...

Keyword(s):

Chromosome Segregation ◽

Chromosomal Instability ◽

Kinase Activity ◽

Fine Tuning ◽

Aurora B ◽

The Novel ◽

Aurora B Kinase ◽

Microtubule Attachment ◽

Molecular Events

The accurate regulation of phosphorylation at the kinetochore is essential for establishing chromosome bi-orientation. Phosphorylation of kinetochore proteins by the Aurora B kinase destabilizes improper kinetochore–microtubule attachments, whereas the phosphatase PP2A has a counteracting role. Imbalanced phosphoregulation leads to error-prone chromosome segregation and aneuploidy, a hallmark of cancer cells. However, little is known about the molecular events that control the balance of phosphorylation at the kinetochore. Here, we show that localization of SET/TAF1, an oncogene product, to centromeres maintains Aurora B kinase activity by inhibiting PP2A, thereby correcting erroneous kinetochore–microtubule attachment. SET localizes at the inner centromere by interacting directly with shugoshin 2, with SET levels declining at increased distances between kinetochore pairs, leading to establishment of chromosome bi-orientation. Moreover, SET overexpression induces chromosomal instability by disrupting kinetochore–microtubule attachment. Thus, our findings reveal the novel role of SET in fine-tuning the phosphorylation level at the kinetochore by balancing the activities of Aurora B and PP2A.

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Centromere-localized Aurora B kinase is required for the fidelity of chromosome segregation

The Journal of Cell Biology ◽

10.1083/jcb.201907092 ◽

2019 ◽

Vol 219 (2) ◽

Cited By ~ 9

Author(s):

Cai Liang ◽

Zhenlei Zhang ◽

Qinfu Chen ◽

Haiyan Yan ◽

Miao Zhang ◽

...

Keyword(s):

Chromosome Segregation ◽

Essential Role ◽

Spindle Assembly Checkpoint ◽

Histone H3 ◽

Spindle Assembly ◽

Aurora B ◽

Aurora B Kinase ◽

Chromosome Missegregation ◽

Proper Timing ◽

Segregation Of Chromosomes

Aurora B kinase plays an essential role in chromosome bi-orientation, which is a prerequisite for equal segregation of chromosomes during mitosis. However, it remains largely unclear whether centromere-localized Aurora B is required for faithful chromosome segregation. Here we show that histone H3 Thr-3 phosphorylation (H3pT3) and H2A Thr-120 phosphorylation (H2ApT120) can independently recruit Aurora B. Disrupting H3pT3-mediated localization of Aurora B at the inner centromere impedes the decline in H2ApT120 during metaphase and causes H2ApT120-dependent accumulation of Aurora B at the kinetochore-proximal centromere. Consequently, silencing of the spindle assembly checkpoint (SAC) is delayed, whereas the fidelity of chromosome segregation is negligibly affected. Further eliminating an H2ApT120-dependent pool of Aurora B restores proper timing for SAC silencing but increases chromosome missegregation. Our data indicate that H2ApT120-mediated localization of Aurora B compensates for the loss of an H3pT3-dependent pool of Aurora B to correct improper kinetochore–microtubule attachments. This study provides important insights into how centromeric Aurora B regulates SAC and kinetochore attachment to microtubules to ensure error-free chromosome segregation.

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Bub1, Sgo1, and Mps1 mediate a distinct pathway for chromosome biorientation in budding yeast

Molecular Biology of the Cell ◽

10.1091/mbc.e10-08-0673 ◽

2011 ◽

Vol 22 (9) ◽

pp. 1473-1485 ◽

Cited By ~ 29

Author(s):

Zuzana Storchová ◽

Justin S. Becker ◽

Nicolas Talarek ◽

Sandra Kögelsberger ◽

David Pellman

Keyword(s):

Chromosome Segregation ◽

Spindle Assembly Checkpoint ◽

Budding Yeast ◽

Spindle Pole ◽

Growth Defect ◽

Aurora B ◽

Mitotic Kinase ◽

Sister Chromatids ◽

Chromosome Alignment ◽

Chromosomal Passenger

The conserved mitotic kinase Bub1 performs multiple functions that are only partially characterized. Besides its role in the spindle assembly checkpoint and chromosome alignment, Bub1 is crucial for the kinetochore recruitment of multiple proteins, among them Sgo1. Both Bub1 and Sgo1 are dispensable for growth of haploid and diploid budding yeast, but they become essential in cells with higher ploidy. We find that overexpression of SGO1 partially corrects the chromosome segregation defect of bub1Δ haploid cells and restores viability to bub1Δ tetraploid cells. Using an unbiased high-copy suppressor screen, we identified two members of the chromosomal passenger complex (CPC), BIR1 (survivin) and SLI15 (INCENP, inner centromere protein), as suppressors of the growth defect of both bub1Δ and sgo1Δ tetraploids, suggesting that these mutants die due to defects in chromosome biorientation. Overexpression of BIR1 or SLI15 also complements the benomyl sensitivity of haploid bub1Δ and sgo1Δ cells. Mutants lacking SGO1 fail to biorient sister chromatids attached to the same spindle pole (syntelic attachment) after nocodazole treatment. Moreover, the sgo1Δ cells accumulate syntelic attachments in unperturbed mitoses, a defect that is partially corrected by BIR1 or SLI15 overexpression. We show that in budding yeast neither Bub1 nor Sgo1 is required for CPC localization or affects Aurora B activity. Instead we identify Sgo1 as a possible partner of Mps1, a mitotic kinase suggested to have an Aurora B–independent function in establishment of biorientation. We found that Sgo1 overexpression rescues defects caused by metaphase inactivation of Mps1 and that Mps1 is required for Sgo1 localization to the kinetochore. We propose that Bub1, Sgo1, and Mps1 facilitate chromosome biorientation independently of the Aurora B–mediated pathway at the budding yeast kinetochore and that both pathways are required for the efficient turnover of syntelic attachments.

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PP2A-B56 opposes Mps1 phosphorylation of Knl1 and thereby promotes spindle assembly checkpoint silencing

The Journal of Cell Biology ◽

10.1083/jcb.201406109 ◽

2014 ◽

Vol 206 (7) ◽

pp. 833-842 ◽

Cited By ~ 96

Author(s):

Antonio Espert ◽

Pelin Uluocak ◽

Ricardo Nunes Bastos ◽

Davinderpreet Mangat ◽

Philipp Graab ◽

...

Keyword(s):

Chromosome Segregation ◽

Mammalian Cells ◽

Feedback Loop ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Eukaryotic Cells ◽

Aurora B ◽

Safeguard Mechanism

The spindle assembly checkpoint (SAC) monitors correct attachment of chromosomes to microtubules, an important safeguard mechanism ensuring faithful chromosome segregation in eukaryotic cells. How the SAC signal is turned off once all the chromosomes have successfully attached to the spindle remains an unresolved question. Mps1 phosphorylation of Knl1 results in recruitment of the SAC proteins Bub1, Bub3, and BubR1 to the kinetochore and production of the wait-anaphase signal. SAC silencing is therefore expected to involve a phosphatase opposing Mps1. Here we demonstrate in vivo and in vitro that BubR1-associated PP2A-B56 is a key phosphatase for the removal of the Mps1-mediated Knl1 phosphorylations necessary for Bub1/BubR1 recruitment in mammalian cells. SAC silencing is thus promoted by a negative feedback loop involving the Mps1-dependent recruitment of a phosphatase opposing Mps1. Our findings extend the previously reported role for BubR1-associated PP2A-B56 in opposing Aurora B and suggest that BubR1-bound PP2A-B56 integrates kinetochore surveillance and silencing of the SAC.

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Bub1 overexpression induces aneuploidy and tumor formation through Aurora B kinase hyperactivation

The Journal of Cell Biology ◽

10.1083/jcb.201012035 ◽

2011 ◽

Vol 193 (6) ◽

pp. 1049-1064 ◽

Cited By ~ 110

Author(s):

Robin M. Ricke ◽

Karthik B. Jeganathan ◽

Jan M. van Deursen

Keyword(s):

Protein Kinase ◽

Transgenic Mice ◽

Chromosome Segregation ◽

Kinase Activity ◽

Tumor Formation ◽

High Expression ◽

Aurora B ◽

Aurora B Kinase ◽

Clinical Prognosis ◽

Poor Clinical Prognosis

High expression of the protein kinase Bub1 has been observed in a variety of human tumors and often correlates with poor clinical prognosis, but its molecular and cellular consequences and role in tumorigenesis are unknown. Here, we demonstrate that overexpression of Bub1 in mice leads to near-diploid aneuploidies and tumor formation. We found that chromosome misalignment and lagging are the primary mitotic errors responsible for the observed aneuploidization. High Bub1 levels resulted in aberrant Bub1 kinase activity and hyperactivation of Aurora B kinase. When Aurora B activity is suppressed, pharmacologically or via BubR1 overexpression, chromosome segregation errors caused by Bub1 overexpression are largely corrected. Importantly, Bub1 transgenic mice overexpressing Bub1 developed various kinds of spontaneous tumors and showed accelerated Myc-induced lymphomagenesis. Our results establish that Bub1 has oncogenic properties and suggest that Aurora B is a critical target through which overexpressed Bub1 drives aneuploidization and tumorigenesis.

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Aurora A kinase phosphorylates Hec1 to regulate metaphase kinetochore–microtubule dynamics

The Journal of Cell Biology ◽

10.1083/jcb.201707160 ◽

2017 ◽

Vol 217 (1) ◽

pp. 163-177 ◽

Cited By ~ 41

Author(s):

Keith F. DeLuca ◽

Amanda Meppelink ◽

Amanda J. Broad ◽

Jeanne E. Mick ◽

Olve B. Peersen ◽

...

Keyword(s):

Chromosome Segregation ◽

Microtubule Dynamics ◽

Aurora B ◽

Aurora A Kinase ◽

Aurora A ◽

Tail Domain ◽

Mitotic Chromosomes ◽

Metaphase Chromosomes ◽

Mitotic Kinases ◽

Microtubule Attachment

Precise regulation of kinetochore–microtubule attachments is essential for successful chromosome segregation. Central to this regulation is Aurora B kinase, which phosphorylates kinetochore substrates to promote microtubule turnover. A critical target of Aurora B is the N-terminal “tail” domain of Hec1, which is a component of the NDC80 complex, a force-transducing link between kinetochores and microtubules. Although Aurora B is regarded as the “master regulator” of kinetochore–microtubule attachment, other mitotic kinases likely contribute to Hec1 phosphorylation. In this study, we demonstrate that Aurora A kinase regulates kinetochore–microtubule dynamics of metaphase chromosomes, and we identify Hec1 S69, a previously uncharacterized phosphorylation target site in the Hec1 tail, as a critical Aurora A substrate for this regulation. Additionally, we demonstrate that Aurora A kinase associates with inner centromere protein (INCENP) during mitosis and that INCENP is competent to drive accumulation of the kinase to the centromere region of mitotic chromosomes. These findings reveal that both Aurora A and B contribute to kinetochore–microtubule attachment dynamics, and they uncover an unexpected role for Aurora A in late mitosis.

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