Caenorhabditis elegans oocytes detect meiotic errors in the absence of canonical end-on kinetochore attachments

Mitotically dividing cells use a surveillance mechanism, the spindle assembly checkpoint, that monitors the attachment of spindle microtubules to kinetochores as a means of detecting errors. However, end-on kinetochore attachments have not been observed in Caenorhabditis elegans oocytes and chromosomes instead associate with lateral microtubule bundles; whether errors can be sensed in this context is not known. Here, we show that C. elegans oocytes delay key events in anaphase, including AIR-2/Aurora B relocalization to the microtubules, in response to a variety of meiotic defects, demonstrating that errors can be detected in these cells and revealing a mechanism that regulates anaphase progression. This mechanism does not appear to rely on several components of the spindle assembly checkpoint but does require the kinetochore, as depleting kinetochore components prevents the error-induced anaphase delays. These findings therefore suggest that in this system, kinetochores could be involved in sensing meiotic errors using an unconventional mechanism that does not use canonical end-on attachments.

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Novel roles for BicD in pronuclear fusion and meiosis II progression via localization of the CHC/TACC/Msps complex to MII spindles

10.1101/2020.12.22.423980 ◽

2020 ◽

Author(s):

Paula Vazquez-Pianzola ◽

Dirk Beuchle ◽

Gabriela Saro ◽

Greco Hernández ◽

Giovanna Maldonado ◽

...

Keyword(s):

Heavy Chain ◽

Spindle Assembly Checkpoint ◽

Coiled Coil ◽

Spindle Assembly ◽

Meiotic Spindle ◽

C Elegans ◽

Spindle Apparatus ◽

Spindle Microtubules ◽

Mitosis And Meiosis ◽

Overexpressed Gene

ABSTRACTVertebrate Clathrin heavy chain (Chc) plays a moonlighting function during mitosis. Chc forms a complex with TACC3 (Transforming Acidic Coiled Coil 3) and ch-TOG (colonic hepatic tumor overexpressed gene) at the spindle microtubules, forming inter microtubule bridges that stabilize the K-fibers. Since Drosophila Chc is a cargo of the dynein adaptor Bicaudal-D (BicD), we investigated whether BicD regulates Clathrin function at the spindle. We found that BicD localizes, like Chc, to centrosomes and spindles during mitosis and meiosis II, and that Chc interacts with Drosophila TACC (D-TACC). Using deGradFP to reduce the activity of BicD in mature eggs and very young embryos, we uncovered a novel function of BicD in meiosis II. The affected meiosis II products underwent abnormal rounds of additional replications and failed to carry out pronuclear fusion. Pointing to a mechanism, we found that the localization of Clathrin/D-TACC/Minispindles (Msps, homolog of ch-TOG) to the meiosis II spindles was impaired upon BicD knockdown. Furthermore, the meiotic products showed abnormal staining for PH3 and reduced recruitment of spindle assembly checkpoint (SAC) components. Altogether, our results support the notion that BicD performs a key activity in assembling the meiotic spindle apparatus. This function of BicD seems conserved in evolution because C. elegans embryos with reduced activities of these genes developed comparable phenotypes.

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Xenopus oocyte meiosis lacks spindle assembly checkpoint control

The Journal of Cell Biology ◽

10.1083/jcb.201211041 ◽

2013 ◽

Vol 201 (2) ◽

pp. 191-200 ◽

Cited By ~ 30

Author(s):

Hua Shao ◽

Ruizhen Li ◽

Chunqi Ma ◽

Eric Chen ◽

X. Johné Liu

Keyword(s):

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Xenopus Laevis Oocytes ◽

Checkpoint Control ◽

Oocyte Meiosis ◽

Complete Disruption ◽

Spindle Microtubules ◽

Surveillance Mechanism ◽

Mammalian Eggs ◽

Mitosis And Meiosis

The spindle assembly checkpoint (SAC) functions as a surveillance mechanism to detect chromosome misalignment and to delay anaphase until the errors are corrected. The SAC is thought to control mitosis and meiosis, including meiosis in mammalian eggs. However, it remains unknown if meiosis in the eggs of nonmammalian vertebrate species is also regulated by SAC. Using a novel karyotyping technique, we demonstrate that complete disruption of spindle microtubules in Xenopus laevis oocytes did not affect the bivalent-to-dyad transition at the time oocytes are undergoing anaphase I. These oocytes also acquired the ability to respond to parthenogenetic activation, which indicates proper metaphase II arrest. Similarly, oocytes exhibiting monopolar spindles, via inhibition of aurora B or Eg5 kinesin, underwent monopolar anaphase on time and without additional intervention. Therefore, the metaphase-to-anaphase transition in frog oocytes is not regulated by SAC.

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Spindle assembly checkpoint genes reveal distinct as well as overlapping expression that implicates MDF-2/Mad2 in postembryonic seam cell proliferation in Caenorhabditis elegans

BMC Cell Biology ◽

10.1186/1471-2121-11-71 ◽

2010 ◽

Vol 11 (1) ◽

pp. 71 ◽

Cited By ~ 3

Author(s):

Maja Tarailo-Graovac ◽

Jun Wang ◽

Jeffrey SC Chu ◽

Domena Tu ◽

David L Baillie ◽

...

Keyword(s):

Cell Proliferation ◽

Caenorhabditis Elegans ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Seam Cell ◽

Checkpoint Genes

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The right place at the right time: Aurora B kinase localization to centromeres and kinetochores

Essays in Biochemistry ◽

10.1042/ebc20190081 ◽

2020 ◽

Vol 64 (2) ◽

pp. 299-311 ◽

Cited By ~ 2

Author(s):

Amanda J. Broad ◽

Jennifer G. DeLuca

Keyword(s):

Spindle Assembly Checkpoint ◽

Protein Complexes ◽

Centromeric Heterochromatin ◽

Aurora B ◽

Mitotic Chromosomes ◽

Large Protein ◽

Aurora B Kinase ◽

Centromeric Protein ◽

Spindle Microtubules ◽

The Right

Abstract The fidelity of chromosome segregation during mitosis is intimately linked to the function of kinetochores, which are large protein complexes assembled at sites of centromeric heterochromatin on mitotic chromosomes. These key “orchestrators” of mitosis physically connect chromosomes to spindle microtubules and transduce forces through these connections to congress chromosomes and silence the spindle assembly checkpoint. Kinetochore-microtubule attachments are highly regulated to ensure that incorrect attachments are not prematurely stabilized, but instead released and corrected. The kinase activity of the centromeric protein Aurora B is required for kinetochore-microtubule destabilization during mitosis, but how the kinase acts on outer kinetochore substrates to selectively destabilize immature and erroneous attachments remains debated. Here, we review recent literature that sheds light on how Aurora B kinase is recruited to both centromeres and kinetochores and discuss possible mechanisms for how kinase interactions with substrates at distinct regions of mitotic chromosomes are regulated.

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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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Interplay between mitotic kinesins and the Aurora kinase–PP1 (protein phosphatase 1) axis

Biochemical Society Transactions ◽

10.1042/bst20130191 ◽

2013 ◽

Vol 41 (6) ◽

pp. 1761-1765 ◽

Cited By ~ 11

Author(s):

John C. Meadows

Keyword(s):

Protein Phosphatase ◽

Spindle Assembly Checkpoint ◽

Spindle Checkpoint ◽

Aurora Kinase ◽

Protein Phosphatase 1 ◽

Aurora B ◽

Spatial Gradient ◽

Cell Cycle Regulators ◽

Aurora B Kinase ◽

Surveillance Mechanism

Correct transmission of genetic information from mother to daughter cells is necessary for development and survival. Accurate segregation is achieved by bipolar attachment of sister kinetochores in each chromatid pair to spindle microtubules emanating from opposite spindle poles, a process known as chromosome bi-orientation. Achieving this requires dynamic interplay between kinetochore proteins, kinesin motor proteins and cell cycle regulators. Chromosome bi-orientation is monitored by a surveillance mechanism known as the SAC (spindle assembly checkpoint). The Aurora B kinase, which is bound to the inner centromere during early mitosis, plays a central role in both chromosome bi-orientation and the spindle checkpoint. The application of tension across centromeres establishes a spatial gradient of high phosphorylation activity at the inner centromere and low phosphorylation activity at the outer kinetochore. This gradient is further refined by the association of PP1 (protein phosphatase 1) to the outer kinetochore, which stabilizes kinetochore–microtubule interactions and silences the spindle checkpoint by dephosphorylating Aurora B kinase targets when chromosome bi-orientation is achieved. In the present review, I discuss emerging evidence that bidirectional cross-talk between mitotic kinesins and the Aurora kinase–PP1 axis is crucial for co-ordinating chromosome bi-orientation and spindle checkpoint signalling in eukaryotes.

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Evidence that the spindle assembly checkpoint does not regulate APCFzy activity in Drosophila female meiosis

Genome ◽

10.1139/g11-079 ◽

2012 ◽

Vol 55 (1) ◽

pp. 63-67 ◽

Cited By ~ 6

Author(s):

Osamah Batiha ◽

Andrew Swan

Keyword(s):

Chromosome Segregation ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Cyclin B ◽

Meiotic Spindle ◽

Loss Of Function ◽

Female Meiosis ◽

Chromosome Attachment ◽

Spindle Microtubules ◽

Made In

The spindle assembly checkpoint (SAC) plays an important role in mitotic cells to sense improper chromosome attachment to spindle microtubules and to inhibit APCFzy-dependent destruction of cyclin B and Securin; consequent initiation of anaphase until correct attachments are made. In Drosophila , SAC genes have been found to play a role in ensuring proper chromosome segregation in meiosis, possibly reflecting a similar role for the SAC in APCFzy inhibition during meiosis. We found that loss of function mutations in SAC genes, Mad2, zwilch, and mps1, do not lead to the predicted rise in APCFzy-dependent degradation of cyclin B either globally throughout the egg or locally on the meiotic spindle. Further, the SAC is not responsible for the inability of APCFzy to target cyclin B and promote anaphase in metaphase II arrested eggs from cort mutant females. Our findings support the argument that SAC proteins play checkpoint independent roles in Drosophila female meiosis and that other mechanisms must function to control APC activity.

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Aurora-A promotes the establishment of spindle assembly checkpoint by priming the Haspin-Aurora-B feedback loop in late G2 phase

Cell Discovery ◽

10.1038/celldisc.2016.49 ◽

2017 ◽

Vol 3 (1) ◽

Cited By ~ 11

Author(s):

Fazhi Yu ◽

Ya Jiang ◽

Lucy Lu ◽

Mimi Cao ◽

Yulong Qiao ◽

...

Keyword(s):

Feedback Loop ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Aurora B ◽

Aurora A ◽

G2 Phase

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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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