Male meiotic spindle features that efficiently segregate paired and lagging chromosomes

AbstractChromosome segregation during male meiosis is tailored to rapidly generate multitudes of sperm. Little, however, is known about the mechanisms that efficiently segregate chromosomes to produce sperm. Using live imaging in Caenorhabditis elegans, we find that spermatocytes exhibit simultaneous pole-to-chromosome shortening (anaphase A) and pole-to-pole elongation (anaphase B). Electron tomography unexpectedly revealed that spermatocyte anaphase A does not stem from kinetochore microtubule shortening. Instead, movement is driven by changes in distance between chromosomes, microtubules, and centrosomes upon tension release at anaphase onset. We also find that the lagging X chromosome, a distinctive feature of anaphase I in C. elegans males, is due to lack of chromosome pairing. The unpaired chromosome remains tethered to centrosomes by continuously lengthening kinetochore microtubules which are under tension, suggesting a ‘tug of war’ that can reliably resolve chromosome lagging. Overall, we define features that partition both paired and lagging chromosomes for optimal sperm production.

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Male meiotic spindle features that efficiently segregate paired and lagging chromosomes

eLife ◽

10.7554/elife.50988 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 4

Author(s):

Gunar Fabig ◽

Robert Kiewisz ◽

Norbert Lindow ◽

James A Powers ◽

Vanessa Cota ◽

...

Keyword(s):

Chromosome Segregation ◽

Electron Tomography ◽

Male Meiosis ◽

Meiotic Spindle ◽

Sperm Production ◽

C Elegans ◽

Unpaired Chromosome ◽

Meiotic Spindles ◽

Anaphase B ◽

Distance Change

Chromosome segregation during male meiosis is tailored to rapidly generate multitudes of sperm. Little is known about mechanisms that efficiently partition chromosomes to produce sperm. Using live imaging and tomographic reconstructions of spermatocyte meiotic spindles in Caenorhabditis elegans, we find the lagging X chromosome, a distinctive feature of anaphase I in C. elegans males, is due to lack of chromosome pairing. The unpaired chromosome remains tethered to centrosomes by lengthening kinetochore microtubules, which are under tension, suggesting that a ‘tug of war’ reliably resolves lagging. We find spermatocytes exhibit simultaneous pole-to-chromosome shortening (anaphase A) and pole-to-pole elongation (anaphase B). Electron tomography unexpectedly revealed spermatocyte anaphase A does not stem solely from kinetochore microtubule shortening. Instead, movement of autosomes is largely driven by distance change between chromosomes, microtubules, and centrosomes upon tension release during anaphase. Overall, we define novel features that segregate both lagging and paired chromosomes for optimal sperm production.

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The Drosophila Kinesin-like Protein KLP67A Is Essential for Mitotic and Male Meiotic Spindle Assembly

Molecular Biology of the Cell ◽

10.1091/mbc.e03-05-0342 ◽

2004 ◽

Vol 15 (1) ◽

pp. 121-131 ◽

Cited By ~ 58

Author(s):

Rita Gandhi ◽

Silvia Bonaccorsi ◽

Diana Wentworth ◽

Stephen Doxsey ◽

Maurizio Gatti ◽

...

Keyword(s):

Cell Division ◽

Chromosome Segregation ◽

Mutational Analysis ◽

Spindle Assembly ◽

Male Meiosis ◽

Meiotic Spindle ◽

Drosophila Cell ◽

Centrosome Separation ◽

Mutant Cells

We have performed a mutational analysis together with RNA interference to determine the role of the kinesin-like protein KLP67A in Drosophila cell division. During both mitosis and male meiosis, Klp67A mutations cause an increase in MT length and disrupt discrete aspects of spindle assembly, as well as cytokinesis. Mutant cells exhibit greatly enlarged metaphase spindle as a result of excessive MT polymerization. The analysis of both living and fixed cells also shows perturbations in centrosome separation, chromosome segregation, and central spindle assembly. These data demonstrate that the MT plus end-directed motor KLP67A is essential for spindle assembly during mitosis and male meiosis and suggest that the regulation of MT plus-end polymerization is a key determinant of spindle architecture throughout cell division.

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Bipolar spindle attachments affect redistributions of ZW10, a Drosophila centromere/kinetochore component required for accurate chromosome segregation.

The Journal of Cell Biology ◽

10.1083/jcb.134.5.1127 ◽

1996 ◽

Vol 134 (5) ◽

pp. 1127-1140 ◽

Cited By ~ 67

Author(s):

B C Williams ◽

M Gatti ◽

M L Goldberg

Keyword(s):

Chromosome Segregation ◽

Male Meiosis ◽

Chromosome Behavior ◽

Bipolar Spindle ◽

Chromosome Missegregation ◽

Spindle Poles ◽

Anaphase Onset ◽

Sister Chromatids ◽

Chromosome Separation ◽

Meiosis I

Previous efforts have shown that mutations in the Drosophila ZW10 gene cause massive chromosome missegregation during mitotic divisions in several tissues. Here we demonstrate that mutations in ZW10 also disrupt chromosome behavior in male meiosis I and meiosis II, indicating that ZW10 function is common to both equational and reductional divisions. Divisions are apparently normal before anaphase onset, but ZW10 mutants exhibit lagging chromosomes and irregular chromosome segregation at anaphase. Chromosome missegregation during meiosis I of these mutants is not caused by precocious separation of sister chromatids, but rather the nondisjunction of homologs. ZW10 is first visible during prometaphase, where it localizes to the kinetochores of the bivalent chromosomes (during meiosis I) or to the sister kinetochores of dyads (during meiosis II). During metaphase of both divisions, ZW10 appears to move from the kinetochores and to spread toward the poles along what appear to be kinetochore microtubules. Redistributions of ZW10 at metaphase require bipolar attachments of individual chromosomes or paired bivalents to the spindle. At the onset of anaphase I or anaphase II, ZW10 rapidly relocalizes to the kinetochore regions of the separating chromosomes. In other mutant backgrounds in which chromosomes lag during anaphase, the presence or absence of ZW10 at a particular kinetochore predicts whether or not the chromosome moves appropriately to the spindle poles. We propose that ZW10 acts as part of, or immediately downstream of, a tension-sensing mechanism that regulates chromosome separation or movement at anaphase onset.

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Katanin controls mitotic and meiotic spindle length

The Journal of Cell Biology ◽

10.1083/jcb.200608117 ◽

2006 ◽

Vol 175 (6) ◽

pp. 881-891 ◽

Cited By ~ 198

Author(s):

Karen McNally ◽

Anjon Audhya ◽

Karen Oegema ◽

Francis J. McNally

Keyword(s):

Chromosome Segregation ◽

Eukaryotic Cell ◽

Meiotic Spindle ◽

Mitotic Spindles ◽

Wild Type ◽

Female Meiosis ◽

C Elegans ◽

Microtubule Severing ◽

Spindle Poles ◽

Type C

Accurate control of spindle length is a conserved feature of eukaryotic cell division. Lengthening of mitotic spindles contributes to chromosome segregation and cytokinesis during mitosis in animals and fungi. In contrast, spindle shortening may contribute to conservation of egg cytoplasm during female meiosis. Katanin is a microtubule-severing enzyme that is concentrated at mitotic and meiotic spindle poles in animals. We show that inhibition of katanin slows the rate of spindle shortening in nocodazole-treated mammalian fibroblasts and in untreated Caenorhabditis elegans meiotic embryos. Wild-type C. elegans meiotic spindle shortening proceeds through an early katanin-independent phase marked by increasing microtubule density and a second, katanin-dependent phase that occurs after microtubule density stops increasing. In addition, double-mutant analysis indicated that γ-tubulin–dependent nucleation and microtubule severing may provide redundant mechanisms for increasing microtubule number during the early stages of meiotic spindle assembly.

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The kinesin-like protein CENP-E is kinetochore-associated throughout poleward chromosome segregation during anaphase-A

Journal of Cell Science ◽

10.1242/jcs.109.5.961 ◽

1996 ◽

Vol 109 (5) ◽

pp. 961-969 ◽

Cited By ~ 1

Author(s):

K.D. Brown ◽

K.W. Wood ◽

D.W. Cleveland

Keyword(s):

Chromosome Segregation ◽

Chromosome Movement ◽

Initial Alignment ◽

Late Prophase ◽

Nuclear Envelope Breakdown ◽

Anaphase Onset ◽

Spindle Elongation ◽

Anaphase B

The kinesin-like protein CENP-E transiently associates with kinetochores following nuclear envelope breakdown in late prophase, remains bound throughout metaphase, but sometime after anaphase onset it releases and by telophase becomes bound to interzonal microtubules of the mitotic spindle. Inhibition of poleward chromosome movement in vitro by CENP-E antibodies and association of CENP-E with minus-end directed microtubule motility in vitro have combined to suggest a key role for CENP-E as an anaphase chromosome motor. For this to be plausible in vivo depends on whether CENP-E remains kinetochore associated during anaphase. Using Indian muntjac cells whose seven chromosomes have large, easily tracked kinetochores, we now show that CENP-E is kinetochore-associated throughout the entirety of anaphase-A (poleward chromosome movement), relocating gradually during spindle elongation (anaphase-B) to the interzonal microtubules. These observations support roles for CENP-E not only in the initial alignment of chromosomes at metaphase and in spindle elongation in anaphase-B, but also in poleward chromosome movement in anaphase-A.

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Conservation of the Centromere/Kinetochore Protein ZW10

The Journal of Cell Biology ◽

10.1083/jcb.138.6.1289 ◽

1997 ◽

Vol 138 (6) ◽

pp. 1289-1301 ◽

Cited By ~ 68

Author(s):

Daniel A. Starr ◽

Byron C. Williams ◽

Zexiao Li ◽

Bijan Etemad-Moghadam ◽

R. Kelly Dawe ◽

...

Keyword(s):

Cell Cycle ◽

Chromosome Segregation ◽

Metaphase Plate ◽

C Elegans ◽

Anaphase Onset ◽

A Cell ◽

Cycle Dependent ◽

Related Proteins ◽

Drosophila Cells

Mutations in the essential Drosophila melanogaster gene zw10 disrupt chromosome segregation, producing chromosomes that lag at the metaphase plate during anaphase of mitosis and both meiotic divisions. Recent evidence suggests that the product of this gene, DmZW10, acts at the kinetochore as part of a tension-sensing checkpoint at anaphase onset. DmZW10 displays an intriguing cell cycle–dependent intracellular distribution, apparently moving from the centromere/kinetochore at prometaphase to kinetochore microtubules at metaphase, and back to the centromere/kinetochore at anaphase (Williams, B.C., M. Gatti, and M.L. Goldberg. 1996. J. Cell Biol. 134:1127-1140). We have identified ZW10-related proteins from widely diverse species with divergent centromere structures, including several Drosophilids, Caenorhabditis elegans, Arabidopsis thaliana, Mus musculus, and humans. Antibodies against the human ZW10 protein display a cell cycle–dependent staining pattern in HeLa cells strikingly similar to that previously observed for DmZW10 in dividing Drosophila cells. Injections of C. elegans ZW10 antisense RNA phenocopies important aspects of the mutant phenotype in Drosophila: these include a strong decrease in brood size, suggesting defects in meiosis or germline mitosis, a high percentage of lethality among the embryos that are produced, and the appearance of chromatin bridges at anaphase. These results indicate that at least some aspects of the functional role of the ZW10 protein in ensuring proper chromosome segregation are conserved across large evolutionary distances.

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Multiple motors cooperate to establish and maintain acentrosomal spindle bipolarity in C. elegans oocyte meiosis

10.1101/2021.09.09.459640 ◽

2021 ◽

Author(s):

Gabriel Cavin-Meza ◽

Michelle M. Kwan ◽

Sarah M. Wignall

Keyword(s):

Chromosome Segregation ◽

Meiotic Spindle ◽

Complete Dissolution ◽

C Elegans ◽

Spindle Poles ◽

Oocyte Meiosis ◽

Monopolar Spindle ◽

Spindle Stability ◽

Bipolar Spindles ◽

Spindle Structure

ABSTRACTWhile centrosomes organize spindle poles during mitosis, oocyte meiosis can occur in their absence. Spindles in human oocytes frequently fail to maintain bipolarity and consequently undergo chromosome segregation errors, making it important to understand mechanisms that promote acentrosomal spindle stability. To this end, we have optimized the auxin-inducible degron system in C. elegans to remove factors from pre-formed oocyte spindles within minutes and assess effects on spindle structure. This approach revealed that dynein is required to maintain the integrity of acentrosomal poles; removal of dynein from bipolar spindles caused pole splaying, and when coupled with a monopolar spindle induced by depletion of kinesin-12 motor KLP-18, dynein depletion led to a complete dissolution of the monopole. Surprisingly, we went on to discover that following monopole disruption, individual chromosomes were able to reorganize local microtubules and re-establish a miniature bipolar spindle that mediated chromosome segregation. This revealed the existence of redundant microtubule sorting forces that are undetectable when KLP-18 and dynein are active. We found that the kinesin-5 family motor BMK-1 provides this force, uncovering the first evidence that kinesin-5 contributes to C. elegans meiotic spindle organization. Altogether, our studies have revealed how multiple motors are working synchronously to establish and maintain bipolarity in the absence of centrosomes.

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KLP-7 acts through the Ndc80 complex to limit pole number in C. elegans oocyte meiotic spindle assembly

The Journal of Cell Biology ◽

10.1083/jcb.201412010 ◽

2015 ◽

Vol 210 (6) ◽

pp. 917-932 ◽

Cited By ~ 25

Author(s):

Amy A. Connolly ◽

Kenji Sugioka ◽

Chien-Hui Chuang ◽

Joshua B. Lowry ◽

Bruce Bowerman

Keyword(s):

Chromosome Segregation ◽

Spindle Assembly ◽

Spindle Pole ◽

Meiotic Spindle ◽

Meiotic Cell ◽

Bipolar Structure ◽

C Elegans ◽

Spindle Poles ◽

Ndc80 Complex ◽

Bipolar Spindles

During oocyte meiotic cell division in many animals, bipolar spindles assemble in the absence of centrosomes, but the mechanisms that restrict pole assembly to a bipolar state are unknown. We show that KLP-7, the single mitotic centromere–associated kinesin (MCAK)/kinesin-13 in Caenorhabditis elegans, is required for bipolar oocyte meiotic spindle assembly. In klp-7(−) mutants, extra microtubules accumulated, extra functional spindle poles assembled, and chromosomes frequently segregated as three distinct masses during meiosis I anaphase. Moreover, reducing KLP-7 function in monopolar klp-18(−) mutants often restored spindle bipolarity and chromosome segregation. MCAKs act at kinetochores to correct improper kinetochore–microtubule (k–MT) attachments, and depletion of the Ndc-80 kinetochore complex, which binds microtubules to mediate kinetochore attachment, restored bipolarity in klp-7(−) mutant oocytes. We propose a model in which KLP-7/MCAK regulates k–MT attachment and spindle tension to promote the coalescence of early spindle pole foci that produces a bipolar structure during the acentrosomal process of oocyte meiotic spindle assembly.

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