scholarly journals Mutations in orbit/mast reveal that the central spindle is comprised of two microtubule populations, those that initiate cleavage and those that propagate furrow ingression

2004 ◽  
Vol 166 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Yoshihiro H. Inoue ◽  
Matthew S. Savoian ◽  
Takao Suzuki ◽  
Endre Máthé ◽  
Masa-Toshi Yamamoto ◽  
...  

We address the relative roles of astral and central spindle microtubules (MTs) in cytokinesis of Drosophila melanogaster primary spermatocytes. Time-lapse imaging studies reveal that the central spindle is comprised of two MT populations, “interior” central spindle MTs found within the spindle envelope and “peripheral” astral MTs that probe the cytoplasm and initiate cleavage furrows where they contact the cortex and form overlapping bundles. The MT-associated protein Orbit/Mast/CLASP concentrates on interior rather than peripheral central spindle MTs. Interior MTs are preferentially affected in hypomorphic orbit mutants, and consequently the interior central spindle fails to form or is unstable. In contrast, peripheral MTs still probe the cortex and form regions of overlap that recruit the Pav-KLP motor and Aurora B kinase. orbit mutants have disorganized or incomplete anillin and actin rings, and although cleavage furrows initiate, they ultimately regress. Our work identifies a new function for Orbit/Mast/CLASP and identifies a novel MT population involved in cleavage furrow initiation.

2021 ◽  
Vol 220 (6) ◽  
Author(s):  
Lin-Ing Wang ◽  
Tyler DeFosse ◽  
Janet K. Jang ◽  
Rachel A. Battaglia ◽  
Victoria F. Wagner ◽  
...  

The chromosomes in the oocytes of many animals appear to promote bipolar spindle assembly. In Drosophila oocytes, spindle assembly requires the chromosome passenger complex (CPC), which consists of INCENP, Borealin, Survivin, and Aurora B. To determine what recruits the CPC to the chromosomes and its role in spindle assembly, we developed a strategy to manipulate the function and localization of INCENP, which is critical for recruiting the Aurora B kinase. We found that an interaction between Borealin and the chromatin is crucial for the recruitment of the CPC to the chromosomes and is sufficient to build kinetochores and recruit spindle microtubules. HP1 colocalizes with the CPC on the chromosomes and together they move to the spindle microtubules. We propose that the Borealin interaction with HP1 promotes the movement of the CPC from the chromosomes to the microtubules. In addition, within the central spindle, rather than at the centromeres, the CPC and HP1 are required for homologous chromosome bi-orientation.


2020 ◽  
Author(s):  
Lin-Ing Wang ◽  
Tyler DeFosse ◽  
Rachel A. Battaglia ◽  
Victoria F. Wagner ◽  
Kim S. McKim

AbstractThe chromosomes in the oocytes of many animals appear to promote bipolar spindle assembly. In Drosophila oocytes, spindle assembly requires the chromosomal passenger complex (CPC), which consists of INCENP, Borealin, Survivin and Aurora B. To determine what recruits the CPC to the chromosomes and its role in spindle assembly, we developed a strategy to manipulate the function and localization of INCENP, which is critical for recruiting the Aurora B kinase. We found that an interaction between Borealin and HP1 is crucial for the initial recruitment of the CPC to the chromosomes and is sufficient to build kinetochores and recruit spindle microtubules. We also found that HP1 moves from the chromosomes to the spindle microtubules along with the CPC, and based on this, propose a mechanism for how the CPC moves from the chromosomes to the microtubules. Within the central spindle, rather than at the centromeres, the CPC and HP1 are required for homologous chromosome bi-orientation.


2020 ◽  
Vol 64 (2) ◽  
pp. 299-311 ◽  
Author(s):  
Amanda J. Broad ◽  
Jennifer G. DeLuca

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.


Open Biology ◽  
2013 ◽  
Vol 3 (8) ◽  
pp. 130081 ◽  
Author(s):  
Tetsuya Takeda ◽  
Iain M. Robinson ◽  
Matthew M. Savoian ◽  
John R. Griffiths ◽  
Anthony D. Whetton ◽  
...  

Cytokinesis is a highly ordered cellular process driven by interactions between central spindle microtubules and the actomyosin contractile ring linked to the dynamic remodelling of the plasma membrane. The mechanisms responsible for reorganizing the plasma membrane at the cell equator and its coupling to the contractile ring in cytokinesis are poorly understood. We report here that Syndapin, a protein containing an F-BAR domain required for membrane curvature, contributes to the remodelling of the plasma membrane around the contractile ring for cytokinesis. Syndapin colocalizes with phosphatidylinositol 4,5-bisphosphate (PI(4,5)P 2 ) at the cleavage furrow, where it directly interacts with a contractile ring component, Anillin. Accordingly, Anillin is mislocalized during cytokinesis in Syndapin mutants. Elevated or diminished expression of Syndapin leads to cytokinesis defects with abnormal cortical dynamics. The minimal segment of Syndapin, which is able to localize to the cleavage furrow and induce cytokinesis defects, is the F-BAR domain and its immediate C-terminal sequences. Phosphorylation of this region prevents this functional interaction, resulting in reduced ability of Syndapin to bind to and deform membranes. Thus, the dephosphorylated form of Syndapin mediates both remodelling of the plasma membrane and its proper coupling to the cytokinetic machinery.


2017 ◽  
Vol 216 (10) ◽  
pp. 3029-3039 ◽  
Author(s):  
Robin Beaven ◽  
Ricardo Nunes Bastos ◽  
Christos Spanos ◽  
Pierre Romé ◽  
C. Fiona Cullen ◽  
...  

The meiotic spindle is formed without centrosomes in a large volume of oocytes. Local activation of crucial spindle proteins around chromosomes is important for formation and maintenance of a bipolar spindle in oocytes. We found that phosphodocking 14-3-3 proteins stabilize spindle bipolarity in Drosophila melanogaster oocytes. A critical 14-3-3 target is the minus end–directed motor Ncd (human HSET; kinesin-14), which has well-documented roles in stabilizing a bipolar spindle in oocytes. Phospho docking by 14-3-3 inhibits the microtubule binding activity of the nonmotor Ncd tail. Further phosphorylation by Aurora B kinase can release Ncd from this inhibitory effect of 14-3-3. As Aurora B localizes to chromosomes and spindles, 14-3-3 facilitates specific association of Ncd with spindle microtubules by preventing Ncd from binding to nonspindle microtubules in oocytes. Therefore, 14-3-3 translates a spatial cue provided by Aurora B to target Ncd selectively to the spindle within the large volume of oocytes.


2003 ◽  
Vol 14 (8) ◽  
pp. 3325-3341 ◽  
Author(s):  
Reiko Honda ◽  
Roman Körner ◽  
Erich A. Nigg

The function of the Aurora B kinase at centromeres and the central spindle is crucial for chromosome segregation and cytokinesis, respectively. Herein, we have investigated the regulation of human Aurora B by its complex partners inner centromere protein (INCENP) and survivin. We found that overexpression of a catalytically inactive, dominant-negative mutant of Aurora B impaired the localization of the entire Aurora B/INCENP/survivin complex to centromeres and the central spindle and severely disturbed mitotic progression. Similar results were also observed after depletion, by RNA interference, of either Aurora B, INCENP, or survivin. These data suggest that Aurora B kinase activity and the formation of the Aurora B/INCENP/survivin complex both contribute to its proper localization. Using recombinant proteins, we found that Aurora B kinase activity was stimulated by INCENP and that the C-terminal region of INCENP was sufficient for activation. Under identical assay conditions, survivin did not detectably influence kinase activity. Human INCENP was a substrate of Aurora B and mass spectrometry identified three consecutive residues (threonine 893, serine 894, and serine 895) containing at least two phosphorylation sites. A nonphosphorylatable mutant (TSS893–895AAA) was a poor activator of Aurora B, demonstrating that INCENP phosphorylation is important for kinase activation.


2003 ◽  
Vol 160 (7) ◽  
pp. 993-999 ◽  
Author(s):  
Elisabetta Bucciarelli ◽  
Maria Grazia Giansanti ◽  
Silvia Bonaccorsi ◽  
Maurizio Gatti

Alarge body of work indicates that chromosomes play a key role in the assembly of both acentrosomal and centrosome-containing spindles. In animal systems, the absence of chromosomes either prevents spindle formation or allows the assembly of a metaphase-like spindle that fails to evolve into an ana-telophase spindle. Here, we show that Drosophila secondary spermatocytes can assemble morphologically normal spindles in the absence of chromosomes. The Drosophila mutants fusolo and solofuso are severely defective in chromosome segregation and produce secondary spermatocytes that are devoid of chromosomes. The centrosomes of these anucleated cells form robust asters that give rise to bipolar spindles that undergo the same ana-telophase morphological transformations that characterize normal spindles. The cells containing chromosome-free spindles are also able to assemble regular cytokinetic structures and cleave normally. In addition, chromosome-free spindles normally accumulate the Aurora B kinase at their midzones. This suggests that the association of Aurora B with chromosomes is not a prerequisite for its accumulation at the central spindle, or for its function during cytokinesis.


2002 ◽  
Vol 13 (9) ◽  
pp. 3064-3077 ◽  
Author(s):  
Margaret A. Bolton ◽  
Weijie Lan ◽  
Shannon E. Powers ◽  
Mark L. McCleland ◽  
Jian Kuang ◽  
...  

Aurora B regulates chromosome segregation and cytokinesis and is the first protein to be implicated as a regulator of bipolar attachment of spindle microtubules to kinetochores. Evidence from several systems suggests that Aurora B is physically associated with inner centromere protein (INCENP) in mitosis and has genetic interactions with Survivin. It is unclear whether the Aurora B and INCENP interaction is cell cycle regulated and if Survivin physically interacts in this complex. In this study, we cloned theXenopus Survivin gene, examined its association with Aurora B and INCENP, and determined the effect of its binding on Aurora B kinase activity. We demonstrate that in the Xenopusearly embryo, all of the detectable Survivin is in a complex with both Aurora B and INCENP throughout the cell cycle. Survivin and Aurora B bind different domains on INCENP. Aurora B activity is stimulated >10-fold in mitotic extracts; this activation is phosphatase sensitive, and the binding of Survivin is required for full Aurora B activity. We also find the hydrodynamic properties of the Aurora B/Survivin/INCENP complex are cell cycle regulated. Our data indicate that Aurora B kinase activity is regulated by both Survivin binding and cell cycle-dependent phosphorylation.


2008 ◽  
Vol 181 (5) ◽  
pp. 777-790 ◽  
Author(s):  
Roger Albertson ◽  
Jian Cao ◽  
Tao-shih Hsieh ◽  
William Sullivan

During cytokinesis, cleavage furrow invagination requires an actomyosin-based contractile ring and addition of new membrane. Little is known about how this actin and membrane traffic to the cleavage furrow. We address this through live analysis of fluorescently tagged vesicles in postcellularized Drosophila melanogaster embryos. We find that during cytokinesis, F-actin and membrane are targeted as a unit to invaginating furrows through formation of F-actin–associated vesicles. F-actin puncta strongly colocalize with endosomal, but not Golgi-derived, vesicles. These vesicles are recruited to the cleavage furrow along the central spindle and a distinct population of microtubules (MTs) in contact with the leading furrow edge (furrow MTs). We find that Rho-specific guanine nucleotide exchange factor mutants, pebble (pbl), severely disrupt this F-actin–associated vesicle transport. These transport defects are a consequence of the pbl mutants' inability to properly form furrow MTs and the central spindle. Transport of F-actin–associated vesicles on furrow MTs and the central spindle is thus an important mechanism by which actin and membrane are delivered to the cleavage furrow.


2014 ◽  
Vol 204 (6) ◽  
pp. 947-963 ◽  
Author(s):  
Budhaditya Banerjee ◽  
Cortney A. Kestner ◽  
P. Todd Stukenberg

The Aurora B kinase coordinates kinetochore–microtubule attachments with spindle checkpoint signaling on each mitotic chromosome. We find that EB1, a microtubule plus end–tracking protein, is required to enrich Aurora B at inner centromeres in a microtubule-dependent manner. This regulates phosphorylation of both kinetochore and chromatin substrates. EB1 regulates the histone phosphorylation marks (histone H2A phospho-Thr120 and histone H3 phospho-Thr3) that localize Aurora B. The chromosomal passenger complex containing Aurora B can be found on a subset of spindle microtubules that exist near prometaphase kinetochores, known as preformed K-fibers (kinetochore fibers). Our data suggest that EB1 enables the spindle microtubules to regulate the phosphorylation of kinetochores through recruitment of the Aurora B kinase.


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