Meiotic Spindle Assembly and Chromosome Segregation in Oocytes

Dumont, Julien; Brunet, Stéphane

doi:10.1002/9780470687970.ch10

Cited by 8 publications

(7 citation statements)

References 122 publications

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“…218 This foundational biochemical approach has complemented a series of more recent live cell imaging studies that have focused directly on processes such as spindle dynamics and chromosome segregation. 220 The biological relevance of studies of this kind bear directly on the problem of age-related aneuploidy and the mechanistic origins of chromosome imbalance propagated during meiotic maturation (see Chapters 1 and 37) 219 By introducing reporter constructs for the cytoskeleton, and tracking individual mouse oocytes over the course of meiotic maturation, novel insights have been obtained that provide a workable hypothesis for how, in the absence of classical centrosomes, MTOCs orchestrate the morphogenesis of the meiotic spindle through self-assembly intervals coinciding with important cell cycle transitions.…”

Section: The Meiotic Spindle: a Microtubule-based Scaffoldmentioning

confidence: 99%

The Mammalian Oocyte

Albertini

2015

Knobil and Neill's Physiology of Reproduction

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Section: The Meiotic Spindle: a Microtubule-based Scaffoldmentioning

confidence: 99%

The Mammalian Oocyte

Albertini

2015

Knobil and Neill's Physiology of Reproduction

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“…Electron microscopy indicates that oocyte meiotic spindles lack conventional centriole-containing centrosomes in Drosophila , Caenorhabditis elegans , Xenopus , chicken, rodents, humans and all other mammals analyzed [4, 5]. In contrast, male gametes typically retain their centrosomes (although there are exceptions; [3]) enabling reconstitution of correct centrosome number after fertilization.…”

Section: Oocyte Meiosis Is Acentrosomalmentioning

confidence: 99%

“…The exact composition and structure of these non-centrosomal MTOCs is unclear [5]. In Xenopus oocytes, a single lamellar MTOC assembles a transient microtubule array (TMA) at the base of the nucleus, which is subsequently remodeled into a bipolar spindle [11, 12].…”

Section: Generation Of Spindle Microtubules In the Absence Of Centrosmentioning

confidence: 99%

Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis

Dumont

Desai

2012

Trends in Cell Biology

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154

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The ability to reproduce relies in most eukaryotes on specialized cells called gametes. Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. Fusion of gametes at fertilization reconstitutes diploidy. In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. In mammals, oocyte meiosis is error-prone and underlies the majority of birth aneuploidies. Here, we review recent work on acentrosomal spindle formation and chromosome alignment/separation during oocyte meiosis in different animal models.

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“… The self-organized assembly of acentrosomal meiotic spindles has been extensively studied1 but little is known about how chromosomes segregate on these spindles. Here, we investigate two chromosome-microtubule interaction mechanisms—kinetochores and chromokinesins—during meiosis in fertilized C. elegans oocytes.…”

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A kinetochore-independent mechanism drives anaphase chromosome separation during acentrosomal meiosis

2010

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The self-organized assembly of acentrosomal meiotic spindles has been extensively studied 1 but little is known about how chromosomes segregate on these spindles. Here, we investigate two chromosome-microtubule interaction mechanisms-kinetochores and chromokinesins-during meiosis in fertilized C. elegans oocytes. We show that the conserved kinetochore protein KNL-1 directs assembly of meiotic kinetochores that orient chromosomes on the acentrosomal spindles. However, in contrast to mitosis, chromosome separation during meiotic anaphase was kinetochore-independent. The chromokinesin KLP-19 did not contribute to chromosome orientation or anaphase, but stabilized late anaphase spindles. Prior to anaphase separation, meiotic kinetochores and spindle poles disassembled along with microtubules on the poleward side of the chromosomes; during anaphase, microtubules were formed between the separating chromosomes. Functional analysis implicated a set of proteins that localize to a ring-shaped domain between the kinetochores in pre-anaphase spindle assembly and anaphase separation. Ring domain proteins are localized by the chromosomal passenger complex (CPC), whose local enrichment is patterned by recombination to control step-wise loss of meiotic cohesion [2][3][4] . Thus, meiotic segregation in C. elegans is a two-stage process where kinetochores orient chromosomes but are dispensable for their separation. We suggest that separation is instead controlled by a meiosis-specific chromosomal domain to coordinate step-wise dissolution of cohesion with chromosome segregation. KeywordsMeiosis; Chromosome segregation; Kinetochore; Centromere; Bub1; Clasp; Microtubule; Spindle To study chromosome segregation on acentrosomal meiotic spindles, we used fertilized C. elegans oocytes because both female meiotic divisions and the first embryonic division can be monitored ex-utero. Assembly on a chromatin base containing the histone H3 variant CENP-A (CENtromeric Protein-A) is a universal feature of mitotic kinetochores that is conserved in C. elegans, despite the fact that it has holocentric chromosomes with kinetochores that run along along the length of each chromatid 5 . In contrast to CENP-Adirected mitotic assembly, a CENP-A-independent mechanism recruits kinetochore @ Corresponding author abdesai@ucsd.edu Phone: (858)-534-9698 Fax: (858)-534-7750 Address: CMM-E Rm 3052, 9500 Gilman Dr, La Jolla, CA 92093-0653. AUTHOR CONTRIBUTIONS All experimental data were generated by J.D., who also had primary responsibility for experimental design and data analysis. A.D. and K.O. contributed to experimental design and data analysis. J.D., A.D. and K.O. wrote the manuscript. COMPETING FINANCIAL INTERESTSThe authors declare no competing financial interests. In C. elegans, fertilization is followed by two rounds of meiotic chromosome segregation. During both meiotic divisions, the 6 chromosomes adopt a compact oval shape and kinetochore components accumulate on their surface in two opposing cup-like structures (Fig. 1a) separated by a ga...

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Meiotic Spindle Assembly and Chromosome Segregation in Oocytes

Cited by 8 publications

References 122 publications

The Mammalian Oocyte

The Mammalian Oocyte

Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis

A kinetochore-independent mechanism drives anaphase chromosome separation during acentrosomal meiosis

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