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

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

The Journal of Cell Biology ◽

10.1083/jcb.201608042 ◽

2017 ◽

Vol 216 (5) ◽

pp. 1243-1253 ◽

Cited By ~ 12

Author(s):

Amanda C. Davis-Roca ◽

Christina C. Muscat ◽

Sarah M. Wignall

Keyword(s):

Caenorhabditis Elegans ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Aurora B ◽

C Elegans ◽

Dividing Cells ◽

Spindle Microtubules ◽

Surveillance Mechanism ◽

Key Events

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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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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Meiotic spindle assembly checkpoint and aneuploidy in males versus females

Cellular and Molecular Life Sciences ◽

10.1007/s00018-018-2986-6 ◽

2018 ◽

Vol 76 (6) ◽

pp. 1135-1150 ◽

Cited By ~ 10

Author(s):

Simon Lane ◽

Liisa Kauppi

Keyword(s):

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Meiotic Spindle

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The Des-1 protein, required for central spindle assembly and cytokinesis, is associated with mitochondria along the meiotic spindle apparatus and with the contractile ring during male meiosis in Drosophila melanogaster

MGG Molecular & General Genetics ◽

10.1007/s004380050861 ◽

1998 ◽

Vol 259 (6) ◽

pp. 664-673 ◽

Cited By ~ 12

Author(s):

J. Basu ◽

Z. Li

Keyword(s):

Drosophila Melanogaster ◽

Spindle Assembly ◽

Male Meiosis ◽

Meiotic Spindle ◽

Contractile Ring ◽

Central Spindle ◽

Spindle Apparatus

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Regulated lipid synthesis and LEM2/CHMP7 jointly control nuclear envelope closure

The Journal of Cell Biology ◽

10.1083/jcb.201908179 ◽

2020 ◽

Vol 219 (5) ◽

Cited By ~ 7

Author(s):

Lauren Penfield ◽

Raakhee Shankar ◽

Erik Szentgyörgyi ◽

Alyssa Laffitte ◽

Michael Sean Mauro ◽

...

Keyword(s):

Nuclear Envelope ◽

De Novo ◽

Lipid Synthesis ◽

Meiotic Spindle ◽

Permeability Barrier ◽

3D Analysis ◽

C Elegans ◽

Cytoplasmic Membranes ◽

Spindle Microtubules ◽

Glycerolipid Synthesis

The nuclear permeability barrier depends on closure of nuclear envelope (NE) holes. Here, we investigate closure of the NE opening surrounding the meiotic spindle in C. elegans oocytes. ESCRT-III components accumulate at the opening but are not required for nuclear closure on their own. 3D analysis revealed cytoplasmic membranes directly adjacent to NE holes containing meiotic spindle microtubules. We demonstrate that the NE protein phosphatase, CNEP-1/CTDNEP1, controls de novo glycerolipid synthesis through lipin to prevent invasion of excess ER membranes into NE holes and a defective NE permeability barrier. Loss of NE adaptors for ESCRT-III exacerbates ER invasion and nuclear permeability defects in cnep-1 mutants, suggesting that ESCRTs restrict excess ER membranes during NE closure. Restoring glycerolipid synthesis in embryos deleted for CNEP-1 and ESCRT components rescued NE permeability defects. Thus, regulating the production and feeding of ER membranes into NE holes together with ESCRT-mediated remodeling is required for nuclear closure.

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Acentrosomal spindle assembly and stability in C. elegans oocytes requires a kinesin-12 non-motor microtubule interaction domain

10.1101/2021.06.17.448874 ◽

2021 ◽

Author(s):

Ian Daniel Wolff ◽

Jeremy Alden Hollis ◽

Sarah Marie Wignall

Keyword(s):

Adaptor Protein ◽

Direct Interaction ◽

Spindle Assembly ◽

Meiotic Spindle ◽

Interaction Domain ◽

Microtubule Binding ◽

C Elegans ◽

Insight Into

During the meiotic divisions in oocytes, microtubules are sorted and organized by motor proteins to generate a bipolar spindle in the absence of centrosomes. In most organisms, kinesin-5 family members crosslink and slide microtubules to generate outward force that promotes acentrosomal spindle bipolarity. However, the mechanistic basis for how other kinesin families act on acentrosomal spindles has not been explored. We investigated this question in C. elegans oocytes, where kinesin-5 is not required to generate outward force. Instead, the kinesin-12 family motor KLP-18 performs this function. KLP-18 acts with adaptor protein MESP-1 (meiotic spindle 1) to sort microtubule minus ends to the periphery of a microtubule array, where they coalesce into spindle poles. If either of these proteins is depleted, outward sorting of microtubules is lost and minus ends converge to form a monoaster. Here we use a combination of in vitro biochemical assays and in vivo mutant analysis to provide insight into the mechanism by which these proteins collaborate to promote acentrosomal spindle assembly. We identify a microtubule binding site on the C-terminal stalk of KLP-18 and demonstrate that a direct interaction between the KLP-18 stalk and MESP-1 activates non-motor microtubule binding. We also provide evidence that this C-terminal domain is required for KLP-18 activity during spindle assembly and show that KLP-18 is continuously required to maintain spindle bipolarity. This study thus provides new insight into the construction and maintenance of the oocyte acentrosomal spindle as well as into kinesin-12 mechanism and regulation.

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The Spindle Assembly Checkpoint Functions during Early Development in Non-Chordate Embryos

Cells ◽

10.3390/cells9051087 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1087

Author(s):

Janet Chenevert ◽

Marianne Roca ◽

Lydia Besnardeau ◽

Antonella Ruggiero ◽

Dalileh Nabi ◽

...

Keyword(s):

Early Development ◽

Spindle Assembly Checkpoint ◽

Sea Urchins ◽

Volume Ratio ◽

Spindle Assembly ◽

Mitotic Progression ◽

Checkpoint Response ◽

Ascidian Embryos ◽

Spindle Microtubules ◽

Prolonged Delay

In eukaryotic cells, a spindle assembly checkpoint (SAC) ensures accurate chromosome segregation, by monitoring proper attachment of chromosomes to spindle microtubules and delaying mitotic progression if connections are erroneous or absent. The SAC is thought to be relaxed during early embryonic development. Here, we evaluate the checkpoint response to lack of kinetochore-spindle microtubule interactions in early embryos of diverse animal species. Our analysis shows that there are two classes of embryos, either proficient or deficient for SAC activation during cleavage. Sea urchins, mussels, and jellyfish embryos show a prolonged delay in mitotic progression in the absence of spindle microtubules from the first cleavage division, while ascidian and amphioxus embryos, like those of Xenopus and zebrafish, continue mitotic cycling without delay. SAC competence during early development shows no correlation with cell size, chromosome number, or kinetochore to cell volume ratio. We show that SAC proteins Mad1, Mad2, and Mps1 lack the ability to recognize unattached kinetochores in ascidian embryos, indicating that SAC signaling is not diluted but rather actively silenced during early chordate development.

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