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Allais A, FitzHarris G. Absence of a robust mitotic timer mechanism in early preimplantation mouse embryos leads to chromosome instability. Development 2022; 149:275859. [DOI: 10.1242/dev.200391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 05/12/2022] [Indexed: 01/07/2023]
Abstract
ABSTRACT
Preimplantation embryos often consist of a combination of euploid and aneuploid cells, suggesting that safeguards preventing the generation and propagation of aneuploid cells in somatic cells might be deficient in embryos. In somatic cells, a mitotic timer mechanism has been described, in which even a small increase in the duration of M phase can cause a cell cycle arrest in the subsequent interphase, preventing further propagation of cells that have undergone a potentially hazardously long M phase. Here, we report that cell divisions in the mouse embryo and embryonic development continue even after a mitotic prolongation of several hours. However, similar M-phase extensions caused cohesion fatigue, resulting in prematurely separated sister chromatids and the production of micronuclei. Only extreme prolongation of M phase caused a subsequent interphase arrest, through a mechanism involving DNA damage. Our data suggest that the simultaneous absence of a robust mitotic timer and susceptibility of the embryo to cohesion fatigue could contribute to chromosome instability in mammalian embryos.
This article has an associated ‘The people behind the papers’ interview.
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Affiliation(s)
- Adélaïde Allais
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) 1 , H2X 0A9 Montréal, Québec , Canada
| | - Greg FitzHarris
- Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) 1 , H2X 0A9 Montréal, Québec , Canada
- Université de Montréal 2 Department of OBGYN, and Department of Pathology and Cell Biology , , H3T 1C5 Montréal, Québec , Canada
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2
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Cell size and polarization determine cytokinesis furrow ingression dynamics in mouse embryos. Proc Natl Acad Sci U S A 2022; 119:e2119381119. [PMID: 35294282 PMCID: PMC8944651 DOI: 10.1073/pnas.2119381119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The final step of cell division, termed cytokinesis, comprises the constriction of a furrow that divides the cytoplasm to form two daughter cells. Although cytokinesis is well studied in traditional cell systems, how cytokinesis is regulated in complex multicellular settings and during cell-fate decisions is less well understood. Here, using live imaging and physical and molecular interventions, we find that the emergence of cell polarity during mouse embryo morphogenesis dramatically impacts cytokinesis mechanisms. Specifically, the assembly of the apical domain in outer cells locally inhibits the cytokinetic machinery, leading to an unexpected laterally biased cytokinesis. Cytokinesis is the final step of cell division during which a contractile ring forms a furrow that partitions the cytoplasm in two. How furrow ingression is spatiotemporally regulated and how it is adapted to complex cellular environments and developmental transitions remain poorly understood. Here, we examine furrow ingression dynamics in the context of the early mouse embryo and find that cell size is a powerful determinant of furrow ingression speed during reductive cell divisions. In addition, the emergence of cell polarity and the assembly of the apical domain in outer cells locally inhibits the recruitment of cytokinesis components and thereby negatively regulates furrow ingression specifically on one side of the furrow. We show that this biasing of cytokinesis is not dependent upon cell–cell adhesion or shape but rather is cell intrinsic and is caused by a paucity of cytokinetic machinery in the apical domain. The results thus reveal that in the mouse embryo cell polarity directly regulates the recruitment of cytokinetic machinery in a cell-autonomous manner and that subcellular organization can instigate differential force generation and constriction speed in different zones of the cytokinetic furrow.
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3
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So C, Menelaou K, Uraji J, Harasimov K, Steyer AM, Seres KB, Bucevičius J, Lukinavičius G, Möbius W, Sibold C, Tandler-Schneider A, Eckel H, Moltrecht R, Blayney M, Elder K, Schuh M. Mechanism of spindle pole organization and instability in human oocytes. Science 2022; 375:eabj3944. [PMID: 35143306 DOI: 10.1126/science.abj3944] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Human oocytes are prone to assembling meiotic spindles with unstable poles, which can favor aneuploidy in human eggs. The underlying causes of spindle instability are unknown. We found that NUMA (nuclear mitotic apparatus protein)-mediated clustering of microtubule minus ends focused the spindle poles in human, bovine, and porcine oocytes and in mouse oocytes depleted of acentriolar microtubule-organizing centers (aMTOCs). However, unlike human oocytes, bovine, porcine, and aMTOC-free mouse oocytes have stable spindles. We identified the molecular motor KIFC1 (kinesin superfamily protein C1) as a spindle-stabilizing protein that is deficient in human oocytes. Depletion of KIFC1 recapitulated spindle instability in bovine and aMTOC-free mouse oocytes, and the introduction of exogenous KIFC1 rescued spindle instability in human oocytes. Thus, the deficiency of KIFC1 contributes to spindle instability in human oocytes.
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Affiliation(s)
- Chun So
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Katerina Menelaou
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Bourn Hall Clinic, Cambridge, UK
| | - Julia Uraji
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Bourn Hall Clinic, Cambridge, UK
| | - Katarina Harasimov
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Anna M Steyer
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - K Bianka Seres
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Bourn Hall Clinic, Cambridge, UK
| | - Jonas Bucevičius
- Chromatin Labeling and Imaging Group, Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Gražvydas Lukinavičius
- Chromatin Labeling and Imaging Group, Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Wiebke Möbius
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | | | | | - Heike Eckel
- Kinderwunschzentrum Göttingen, Göttingen, Germany
| | | | | | | | - Melina Schuh
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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4
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Blengini CS, Schindler K. Acentriolar spindle assembly in mammalian female meiosis and the consequences of its perturbations on human reproduction. Biol Reprod 2021; 106:253-263. [PMID: 34791041 DOI: 10.1093/biolre/ioab210] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/26/2021] [Accepted: 11/11/2021] [Indexed: 12/18/2022] Open
Abstract
The purpose of meiosis is to generate developmentally competent, haploid gametes with the correct number of chromosomes. For reasons not completely understood, female meiosis is more prone to chromosome segregation errors than meiosis in males, leading to an abnormal number of chromosomes, or aneuploidy, in gametes. Meiotic spindles are the cellular machinery essential for the proper segregation of chromosomes. One unique feature of spindle structures in female meiosis is spindles poles that lack centrioles. The process of building a meiotic spindle without centrioles is complex and requires precise coordination of different structural components, assembly factors, motor proteins, and signaling molecules at specific times and locations to regulate each step. In this review, we discuss the basics of spindle formation during oocyte meiotic maturation focusing on mouse and human studies. Finally, we review different factors that could alter the process of spindle formation and its stability. We conclude with a discussion of how different assisted reproductive technologies (ART) could affect spindles and the consequences these perturbations may have for subsequent embryo development.
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Affiliation(s)
- Cecilia S Blengini
- Rutgers University, Human Genetics Institute of New Jersey, Piscataway, NJ 08854 USA
| | - Karen Schindler
- Rutgers University, Human Genetics Institute of New Jersey, Piscataway, NJ 08854 USA
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Distinct classes of lagging chromosome underpin age-related oocyte aneuploidy in mouse. Dev Cell 2021; 56:2273-2283.e3. [PMID: 34428397 DOI: 10.1016/j.devcel.2021.07.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/07/2021] [Accepted: 07/29/2021] [Indexed: 12/18/2022]
Abstract
Chromosome segregation errors that cause oocyte aneuploidy increase in frequency with maternal age and are considered a major contributing factor of age-related fertility decline in females. Lagging anaphase chromosomes are a common age-associated phenomenon in oocytes, but whether anaphase laggards actually missegregate and cause aneuploidy is unclear. Here, we show that lagging chromosomes in mouse oocytes comprise two mechanistically distinct classes of chromosome motion that we refer to as "class-I" and "class-II" laggards. We use imaging approaches and mechanistic interventions to dissociate the two classes and find that whereas class-II laggards are largely benign, class-I laggards frequently directly lead to aneuploidy. Most notably, a controlled prolongation of meiosis I specifically lessens class-I lagging to prevent aneuploidy. Our data thus reveal lagging chromosomes to be a cause of age-related aneuploidy in mouse oocytes and suggest that manipulating the cell cycle could increase the yield of useful oocytes in some contexts.
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Pandey H, Popov M, Goldstein-Levitin A, Gheber L. Mechanisms by Which Kinesin-5 Motors Perform Their Multiple Intracellular Functions. Int J Mol Sci 2021; 22:6420. [PMID: 34203964 PMCID: PMC8232732 DOI: 10.3390/ijms22126420] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Bipolar kinesin-5 motor proteins perform multiple intracellular functions, mainly during mitotic cell division. Their specialized structural characteristics enable these motors to perform their essential functions by crosslinking and sliding apart antiparallel microtubules (MTs). In this review, we discuss the specialized structural features of kinesin-5 motors, and the mechanisms by which these features relate to kinesin-5 functions and motile properties. In addition, we discuss the multiple roles of the kinesin-5 motors in dividing as well as in non-dividing cells, and examine their roles in pathogenetic conditions. We describe the recently discovered bidirectional motility in fungi kinesin-5 motors, and discuss its possible physiological relevance. Finally, we also focus on the multiple mechanisms of regulation of these unique motor proteins.
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Affiliation(s)
| | | | | | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel; (H.P.); (M.P.); (A.G.-L.)
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Rémillard-Labrosse G, Dean NL, Allais A, Mihajlović AI, Jin SG, Son WY, Chung JT, Pansera M, Henderson S, Mahfoudh A, Steiner N, Agapitou K, Marangos P, Buckett W, Ligeti-Ruiter J, FitzHarris G. Human oocytes harboring damaged DNA can complete meiosis I. Fertil Steril 2020; 113:1080-1089.e2. [PMID: 32276763 DOI: 10.1016/j.fertnstert.2019.12.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To determine whether human oocytes possess a checkpoint to prevent completion of meiosis I when DNA is damaged. DESIGN DNA damage is considered a major threat to the establishment of healthy eggs and embryos. Recent studies found that mouse oocytes with damaged DNA can resume meiosis and undergo germinal vesicle breakdown (GVBD), but then arrest in metaphase of meiosis I in a process involving spindle assembly checkpoint (SAC) signaling. Such a mechanism could help prevent the generation of metaphase II (MII) eggs with damaged DNA. Here, we compared the impact of DNA-damaging agents with nondamaged control samples in mouse and human oocytes. SETTING University-affiliated clinic and research center. PATIENT(S) Patients undergoing ICSI cycles donated GV-stage oocytes after informed consent; 149 human oocytes were collected over 2 years (from 50 patients aged 27-44 years). INTERVENTIONS(S) Mice and human oocytes were treated with DNA-damaging drugs. MAIN OUTCOME MEASURE(S) Oocytes were monitored to evaluate GVBD and polar body extrusion (PBE), in addition to DNA damage assessment with the use of γH2AX antibodies and confocal microscopy. RESULT(S) Whereas DNA damage in mouse oocytes delays or prevents oocyte maturation, most human oocytes harboring experimentally induced DNA damage progress through meiosis I and subsequently form an MII egg, revealing the absence of a DNA damage-induced SAC response. Analysis of the resulting MII eggs revealed damaged DNA and chaotic spindle apparatus, despite the oocyte appearing morphologically normal. CONCLUSION(S) Our data indicate that experimentally induced DNA damage does not prevent PBE in human oocytes and can persist in morphologically normal looking MII eggs.
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Affiliation(s)
| | - Nicola L Dean
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Adélaïde Allais
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada
| | - Aleksandar I Mihajlović
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada; Département d'Obstétrique-Gynécologie, Université de Montréal, Montreal, Quebec, Canada
| | - Shao Guang Jin
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Weon-Young Son
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Jin-Tae Chung
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Melissa Pansera
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Sara Henderson
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Alina Mahfoudh
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Naama Steiner
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Kristy Agapitou
- Department of Applications and Technology, University of Ioannina, Ioannina, Greece; Institute of Life Fertility Unit, IASO Maternity Hospital, Athens, Greece
| | - Petros Marangos
- Department of Applications and Technology, University of Ioannina, Ioannina, Greece; Department of Biomedical Research, Institute of Molecular Biology and Biotechnology-Foundation for Research and Technology, Ioannina, Greece
| | - William Buckett
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Jacob Ligeti-Ruiter
- Reproductive Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | - Greg FitzHarris
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada; Département d'Obstétrique-Gynécologie, Université de Montréal, Montreal, Quebec, Canada.
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8
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She ZY, Zhong N, Yu KW, Xiao Y, Wei YL, Lin Y, Li YL, Lu MH. Kinesin-5 Eg5 is essential for spindle assembly and chromosome alignment of mouse spermatocytes. Cell Div 2020; 15:6. [PMID: 32165913 PMCID: PMC7060529 DOI: 10.1186/s13008-020-00063-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/29/2020] [Indexed: 11/10/2022] Open
Abstract
Background Microtubule organization is essential for bipolar spindle assembly and chromosome segregation, which contribute to genome stability. Kinesin-5 Eg5 is known to be a crucial regulator in centrosome separation and spindle assembly in mammalian somatic cells, however, the functions and mechanisms of Eg5 in male meiotic cell division remain largely unknown. Results In this study, we have found that Eg5 proteins are expressed in mouse spermatogonia, spermatocytes and spermatids. After Eg5 inhibition by specific inhibitors Monastrol, STLC and Dimethylenastron, the meiotic spindles of dividing spermatocytes show spindle collapse and the defects in bipolar spindle formation. We demonstrate that Eg5 regulates spindle bipolarity and the maintenance of meiotic spindles in meiosis. Eg5 inhibition leads to monopolar spindles, spindle abnormalities and chromosome misalignment in cultured GC-2 spd cells. Furthermore, Eg5 inhibition results in the decrease of the spermatids and the abnormalities in mature sperms. Conclusions Our results have revealed an important role of kinesin-5 Eg5 in male meiosis and the maintenance of male fertility. We demonstrate that Eg5 is crucial for bipolar spindle assembly and chromosome alignment in dividing spermatocytes. Our data provide insights into the functions of Eg5 in meiotic spindle assembly of dividing spermatocytes.
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Affiliation(s)
- Zhen-Yu She
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122 Fujian China
| | - Ning Zhong
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Kai-Wei Yu
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Yu Xiao
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350001 Fujian China.,4Fujian Provincial Children's Hospital, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001 Fujian China
| | - Yang Lin
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Yue-Ling Li
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Ming-Hui Lu
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
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Paim LMG, FitzHarris G. Tetraploidy causes chromosomal instability in acentriolar mouse embryos. Nat Commun 2019; 10:4834. [PMID: 31645568 PMCID: PMC6811537 DOI: 10.1038/s41467-019-12772-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 09/20/2019] [Indexed: 11/16/2022] Open
Abstract
Tetraploidisation is considered a common event in the evolution of chromosomal instability (CIN) in cancer cells. The current model for how tetraploidy drives CIN in mammalian cells is that a doubling of the number of centrioles that accompany the genome doubling event leads to multipolar spindle formation and chromosome segregation errors. By exploiting the unusual scenario of mouse blastomeres, which lack centrioles until the ~64-cell stage, we show that tetraploidy can drive CIN by an entirely distinct mechanism. Tetraploid blastomeres assemble bipolar spindles dictated by microtubule organising centres, and multipolar spindles are rare. Rather, kinetochore-microtubule turnover is altered, leading to microtubule attachment defects and anaphase chromosome segregation errors. The resulting blastomeres become chromosomally unstable and exhibit a dramatic increase in whole chromosome aneuploidies. Our results thus reveal an unexpected mechanism by which tetraploidy drives CIN, in which the acquisition of chromosomally-unstable microtubule dynamics contributes to chromosome segregation errors following tetraploidisation.
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Affiliation(s)
- Lia Mara Gomes Paim
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, H2X 0A9, Montreal, QC, Canada
| | - Greg FitzHarris
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, H2X 0A9, Montreal, QC, Canada.
- Département d'Obstétrique-Gynécologie, Université de Montréal, H3T 1C5, Montreal, QC, Canada.
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10
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Abstract
Chromosome segregation errors in human oocytes lead to aneuploid embryos that cause infertility and birth defects. Here we provide an overview of the chromosome-segregation process in the mammalian oocyte, highlighting mechanistic differences between oocytes and somatic cells that render oocytes so prone to segregation error. These differences include the extremely large size of the oocyte cytoplasm, the unique geometry of meiosis-I chromosomes, idiosyncratic function of the spindle assembly checkpoint, and dramatically altered oocyte cell-cycle control and spindle assembly, as compared to typical somatic cells. We summarise recent work suggesting that aging leads to a further deterioration in fidelity of chromosome segregation by impacting multiple components of the chromosome-segregation machinery. In addition, we compare and contrast recent results from mouse and human oocytes, which exhibit overlapping defects to differing extents. We conclude that the striking propensity of the oocyte to mis-segregate chromosomes reflects the unique challenges faced by the spindle in a highly unusual cellular environment.
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Affiliation(s)
- Aleksandar I Mihajlović
- Centre Recherche CHUM and Department OBGYN, Université de Montreal, Montreal, Quebec, Canada
| | - Greg FitzHarris
- Centre Recherche CHUM and Department OBGYN, Université de Montreal, Montreal, Quebec, Canada.
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Hara-Yokoyama M, Kurihara H, Ichinose S, Matsuda H, Ichinose S, Kurosawa M, Tada N, Iwahara C, Terasawa K, Podyma-Inoue KA, Furukawa K, Iwabuchi K. KIF11 as a Potential Marker of Spermatogenesis Within Mouse Seminiferous Tubule Cross-sections. J Histochem Cytochem 2019; 67:813-824. [PMID: 31424977 DOI: 10.1369/0022155419871027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The arrangement of immature germ cells changes regularly and periodically along the axis of the seminiferous tubule, and is used to describe the progression of spermatogenesis. This description is based primarily on the changes in the acrosome and the nuclear morphology of haploid spermatids. However, such criteria cannot be applied under pathological conditions with arrested spermatid differentiation. In such settings, the changes associated with the differentiation of premeiotic germ cells must be analyzed. Here, we found that the unique bipolar motor protein, KIF11 (kinesin-5/Eg5), which functions in spindle formation during mitosis and meiosis in oocytes and early embryos, is expressed in premeiotic germ cells (spermatogonia and spermatocytes). Thus, we aimed to investigate whether KIF11 could be used to describe the progression of incomplete spermatogenesis. Interestingly, KIF11 expression was barely observed in haploid spermatids and Sertoli cells. The KIF11 staining allowed us to evaluate the progression of meiotic processes, by providing the time axis of spindle formation in both normal and spermatogenesis-arrested mutant mice. Accordingly, KIF11 has the potential to serve as an excellent marker to describe spermatogenesis, even in the absence of spermatid development.
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Affiliation(s)
- Miki Hara-Yokoyama
- Department of Biochemistry, Graduate School of Medical and Dental Sciences,Tokyo Medical and Dental University, Tokyo, Japan
| | - Hidetake Kurihara
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Faculty of Health Science, Aino University, Osaka, Japan
| | - Shozo Ichinose
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, Japan
| | - Hironori Matsuda
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, Japan
| | - Shizuko Ichinose
- Plastic Reconstructive & Regenerative Surgery, Nippon Medical School, Tokyo, Japan
| | - Masaru Kurosawa
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, Japan
| | - Norihiro Tada
- Atopy Research Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Chihiro Iwahara
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, Japan
| | - Kazue Terasawa
- Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Katarzyna A Podyma-Inoue
- Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Koichi Furukawa
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Department of Biomedical Sciences, Chubu University, Aichi, Japan
| | - Kazuhisa Iwabuchi
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, Japan
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12
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Namgoong S, Kim NH. Meiotic spindle formation in mammalian oocytes: implications for human infertility. Biol Reprod 2019; 98:153-161. [PMID: 29342242 DOI: 10.1093/biolre/iox145] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 12/27/2017] [Indexed: 12/12/2022] Open
Abstract
In the final stage of oogenesis, mammalian oocytes generate a meiotic spindle and undergo chromosome segregation to yield an egg that is ready for fertilization. Herein, we describe the recent advances in understanding the mechanisms controlling formation of the meiotic spindle in metaphase I (MI) and metaphase II (MII) in mammalian oocytes, and focus on the differences between mouse and human oocytes. Unlike mitotic cells, mammalian oocytes lack typical centrosomes that consist of two centrioles and the surrounding pericentriolar matrix proteins, which serve as microtubule-organizing centers (MTOCs) in most somatic cells. Instead, oocytes rely on different mechanisms for the formation of microtubules in MI spindles. Two different mechanisms have been described for MI spindle formation in mammalian oocytes. Chromosome-mediated microtubule formation, including RAN-mediated spindle formation and chromosomal passenger complex-mediated spindle elongation, controls the growth of microtubules from chromatin, while acentriolar MTOC-mediated microtubule formation contributes to spindle formation. Mouse oocytes utilize both chromatin- and MTOC-mediated pathways for microtubule formation. The existence of both pathways may provide a fail-safe mechanism to ensure high fidelity of chromosome segregation during meiosis. Unlike mouse oocytes, human oocytes considered unsuitable for clinical in vitro fertilization procedures, lack MTOCs; this may explain why meiosis in human oocytes is often error-prone. Understanding the mechanisms of MI/MII spindle formation, spindle assembly checkpoint, and chromosome segregation, in mammalian oocytes, will provide valuable insights into the molecular mechanisms of human infertility.
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Affiliation(s)
| | - Nam-Hyung Kim
- Department of Animal Science, Chungbuk National University, Cheong-Ju, Chungbuk, Republic of Korea
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13
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Letort G, Bennabi I, Dmitrieff S, Nedelec F, Verlhac MH, Terret ME. A computational model of the early stages of acentriolar meiotic spindle assembly. Mol Biol Cell 2019; 30:863-875. [PMID: 30650011 PMCID: PMC6589792 DOI: 10.1091/mbc.e18-10-0644] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/18/2018] [Accepted: 01/09/2019] [Indexed: 11/11/2022] Open
Abstract
The mitotic spindle is an ensemble of microtubules responsible for the repartition of the chromosomal content between the two daughter cells during division. In metazoans, spindle assembly is a gradual process involving dynamic microtubules and recruitment of numerous associated proteins and motors. During mitosis, centrosomes organize and nucleate the majority of spindle microtubules. In contrast, oocytes lack canonical centrosomes but are still able to form bipolar spindles, starting from an initial ball that self-organizes in several hours. Interfering with early steps of meiotic spindle assembly can lead to erroneous chromosome segregation. Although not fully elucidated, this process is known to rely on antagonistic activities of plus end- and minus end-directed motors. We developed a model of early meiotic spindle assembly in mouse oocytes, including key factors such as microtubule dynamics and chromosome movement. We explored how the balance between plus end- and minus end-directed motors, as well as the influence of microtubule nucleation, impacts spindle morphology. In a refined model, we added spatial regulation of microtubule stability and minus-end clustering. We could reproduce the features of early stages of spindle assembly from 12 different experimental perturbations and predict eight additional perturbations. With its ability to characterize and predict chromosome individualization, this model can help deepen our understanding of spindle assembly.
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Affiliation(s)
- Gaelle Letort
- CIRB, Collège de France, UMR7241/U1050, F-75005 Paris, France
| | - Isma Bennabi
- CIRB, Collège de France, UMR7241/U1050, F-75005 Paris, France
| | - Serge Dmitrieff
- Institut Jacques Monod, UMR7592 and Université Paris-Diderot, F-75205 Paris, France
| | - François Nedelec
- Centre de Recherche Interdisciplinaire, F-75004 Paris, France
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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14
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Schneider I, Ellenberg J. Mysteries in embryonic development: How can errors arise so frequently at the beginning of mammalian life? PLoS Biol 2019; 17:e3000173. [PMID: 30840627 PMCID: PMC6422315 DOI: 10.1371/journal.pbio.3000173] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/18/2019] [Indexed: 12/21/2022] Open
Abstract
Chromosome segregation errors occur frequently during female meiosis but also in the first mitoses of mammalian preimplantation development. Such errors can lead to aneuploidy, spontaneous abortions, and birth defects. Some of the mechanisms underlying these errors in meiosis have been deciphered but which mechanisms could cause chromosome missegregation in the first embryonic cleavage divisions is mostly a “mystery”. In this article, we describe the starting conditions and challenges of these preimplantation divisions, which might impair faithful chromosome segregation. We also highlight the pending research to provide detailed insight into the mechanisms and regulation of preimplantation mitoses. Starting a new life is a challenging business. This Essay explores the changes at the oocyte-to-embryo transition to highlight the circumstances under which the very first and decisive — but ‘mysteriously’ error-prone — mitotic divisions occur.
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Affiliation(s)
- Isabell Schneider
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Candidate for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- * E-mail:
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15
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Cell-Size-Independent Spindle Checkpoint Failure Underlies Chromosome Segregation Error in Mouse Embryos. Curr Biol 2019; 29:865-873.e3. [PMID: 30773364 DOI: 10.1016/j.cub.2018.12.042] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/23/2018] [Accepted: 12/21/2018] [Indexed: 12/31/2022]
Abstract
Chromosome segregation errors during mammalian preimplantation development cause "mosaic" embryos comprising a mixture of euploid and aneuploid cells, which reduce the potential for a successful pregnancy [1-5], but why these errors are common is unknown. In most cells, chromosome segregation error is averted by the spindle assembly checkpoint (SAC), which prevents anaphase-promoting complex (APC/C) activation and anaphase onset until chromosomes are aligned with kinetochores attached to spindle microtubules [6, 7], but little is known about the SAC's role in the early mammalian embryo. In C. elegans, the SAC is weak in early embryos, and it strengthens during early embryogenesis as a result of progressively lessening cell size [8, 9]. Here, using live imaging, micromanipulation, gene knockdown, and pharmacological approaches, we show that this is not the case in mammalian embryos. Misaligned chromosomes in the early mouse embryo can recruit SAC components to mount a checkpoint signal, but this signal fails to prevent anaphase onset, leading to high levels of chromosome segregation error. We find that failure of the SAC to prolong mitosis is not attributable to cell size. We show that mild chemical inhibition of APC/C can extend mitosis, thereby allowing more time for correct chromosome alignment and reducing segregation errors. SAC-APC/C disconnect thus presents a mechanistic explanation for frequent chromosome segregation errors in early mammalian embryos. Moreover, our data provide proof of principle that modulation of the SAC-APC/C axis can increase the likelihood of error-free chromosome segregation in cultured mammalian embryos.
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16
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Reichmann J, Nijmeijer B, Hossain MJ, Eguren M, Schneider I, Politi AZ, Roberti MJ, Hufnagel L, Hiiragi T, Ellenberg J. Dual-spindle formation in zygotes keeps parental genomes apart in early mammalian embryos. Science 2018; 361:189-193. [PMID: 30002254 DOI: 10.1126/science.aar7462] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 06/08/2018] [Indexed: 12/24/2022]
Abstract
At the beginning of mammalian life, the genetic material from each parent meets when the fertilized egg divides. It was previously thought that a single microtubule spindle is responsible for spatially combining the two genomes and then segregating them to create the two-cell embryo. We used light-sheet microscopy to show that two bipolar spindles form in the zygote and then independently congress the maternal and paternal genomes. These two spindles aligned their poles before anaphase but kept the parental genomes apart during the first cleavage. This spindle assembly mechanism provides a potential rationale for erroneous divisions into more than two blastomeric nuclei observed in mammalian zygotes and reveals the mechanism behind the observation that parental genomes occupy separate nuclear compartments in the two-cell embryo.
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Affiliation(s)
- Judith Reichmann
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Bianca Nijmeijer
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - M Julius Hossain
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Manuel Eguren
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Isabell Schneider
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Antonio Z Politi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - M Julia Roberti
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Lars Hufnagel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Takashi Hiiragi
- Developmental Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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17
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Al Jord A, Verlhac MH. Spindle Assembly: Two Spindles for Two Genomes in a Mammalian Zygote. Curr Biol 2018; 28:R948-R951. [PMID: 30205069 DOI: 10.1016/j.cub.2018.07.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A single bipolar spindle was thought to form around both parental genomes in zygotes initiating the first division. A recent study challenges this predominant view by showing that two independent spindles assemble to prevent parental genome mixing in mouse zygotes.
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Affiliation(s)
- Adel Al Jord
- CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée FRM, Paris F-75005, France.
| | - Marie-Hélène Verlhac
- CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée FRM, Paris F-75005, France
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18
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Intrinsically Defective Microtubule Dynamics Contribute to Age-Related Chromosome Segregation Errors in Mouse Oocyte Meiosis-I. Curr Biol 2018; 27:1040-1047. [PMID: 28376326 DOI: 10.1016/j.cub.2017.02.025] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/07/2017] [Accepted: 02/10/2017] [Indexed: 12/16/2022]
Abstract
Chromosome segregation errors in mammalian oocytes compromise development and are particularly prevalent in older females, but the aging-related cellular changes that promote segregation errors remain unclear [1, 2]. Aging causes a loss of meiotic chromosome cohesion, which can explain premature disjunction of sister chromatids [3-7], but why intact sister pairs should missegregate in meiosis-I (termed non-disjunction) remains unknown. Here, we show that oocytes from naturally aged mice exhibit substantially altered spindle microtubule dynamics, resulting in transiently multipolar spindles that predispose the oocytes to kinetochore-microtubule attachment defects and missegregation of intact sister chromatid pairs. Using classical micromanipulation approaches, including reciprocally transferring nuclei between young and aged oocytes, we show that altered microtubule dynamics are not attributable to age-related chromatin changes. We therefore report that altered microtubule dynamics is a novel primary lesion contributing to age-related oocyte segregation errors. We propose that, whereas cohesion loss can explain premature sister separation, classical non-disjunction is instead explained by altered microtubule dynamics, leading to aberrant spindle assembly.
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19
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Haverfield J, Dean NL, Nöel D, Rémillard-Labrosse G, Paradis V, Kadoch IJ, FitzHarris G. Tri-directional anaphases as a novel chromosome segregation defect in human oocytes. Hum Reprod 2018; 32:1293-1303. [PMID: 28449121 DOI: 10.1093/humrep/dex083] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/07/2017] [Indexed: 12/17/2022] Open
Abstract
STUDY QUESTION What are the chromosome segregation errors in human oocyte meiosis-I that may underlie oocyte aneuploidy? SUMMARY ANSWER Multiple modes of chromosome segregation error were observed, including tri-directional anaphases, which we attribute to loss of bipolar spindle structure at anaphase-I. WHAT IS KNOWN ALREADY Oocyte aneuploidy is common and associated with infertility, but mechanistic information on the chromosome segregation errors underlying these defects is scarce. Lagging chromosomes were recently reported as a possible mechanism by which segregation errors occur. STUDY DESIGN, SIZE, DURATION Long-term confocal imaging of chromosome dynamics in 50 human oocytes collected between January 2015 and May 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS Germinal vesicle (GV) stage oocytes were collected from women undergoing intracytoplasmic sperm injection cycles and also CD1 mice. Oocytes were microinjected with complementary RNAs to label chromosomes, and in a subset of oocytes, the meiotic spindle. Oocytes were imaged live through meiosis-I using confocal microscopy. 3D image reconstruction was used to classify chromosome segregation phenotypes at anaphase-I. Segregation phenotypes were related to spindle dynamics and cell cycle timings. MAIN RESULTS AND THE ROLE OF CHANCE Most (87%) mouse oocytes segregated chromosomes with no obvious defects. We found that 20% of human oocytes segregated chromosomes bi-directionally with no lagging chromosomes. The rest were categorised as bi-directional anaphase with lagging chromosomes (20%), bi-directional anaphase with chromatin mass separation (34%) or tri-directional anaphase (26%). Segregation errors correlated with chromosome misalignment prior to anaphase. Spindles were tripolar when tri-directional anaphases occurred. Anaphase phenotypes did not correlate with meiosis-I duration (P = 0.73). LARGE SCALE DATA Not applicable. LIMITATIONS, REASONS FOR CAUTION Oocytes were recovered at GV stage after gonadotrophin-stimulation, and the usual oocyte quality caveats apply. Whilst the possibility that imaging may affect oocyte physiology cannot be formally excluded, detailed controls and justifications are presented. WIDER IMPLICATIONS OF THE FINDINGS This is one of the first reports of live imaging of chromosome dynamics in human oocytes, introducing tri-directional anaphases as a novel potential mechanism for oocyte aneuploidy. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by grants from Fondation Jean-Louis Lévesque (Canada), CIHR (MOP142334) and CFI (32711) to GF. JH is supported by Postdoctoral Fellowships from The Lalor Foundation and CIHR (146703). The authors have no conflict of interest.
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Affiliation(s)
- Jenna Haverfield
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), University of Montréal, 900 Rue St Denis, Montréal, Québec, Canada H2X 0A9.,Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada H3T 1J4
| | - Nicola L Dean
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), University of Montréal, 900 Rue St Denis, Montréal, Québec, Canada H2X 0A9.,Clinique de Procréation Assistée (CPA) du CHUM, Montréal, Québec, Canada H2L 4S8
| | - Diana Nöel
- Clinique de Procréation Assistée (CPA) du CHUM, Montréal, Québec, Canada H2L 4S8
| | - Gaudeline Rémillard-Labrosse
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), University of Montréal, 900 Rue St Denis, Montréal, Québec, Canada H2X 0A9
| | - Veronique Paradis
- Clinique de Procréation Assistée (CPA) du CHUM, Montréal, Québec, Canada H2L 4S8
| | - Isaac-Jacques Kadoch
- Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada H3T 1J4.,Clinique de Procréation Assistée (CPA) du CHUM, Montréal, Québec, Canada H2L 4S8
| | - Greg FitzHarris
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), University of Montréal, 900 Rue St Denis, Montréal, Québec, Canada H2X 0A9.,Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada H3T 1J4
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20
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Bennabi I, Quéguiner I, Kolano A, Boudier T, Mailly P, Verlhac MH, Terret ME. Shifting meiotic to mitotic spindle assembly in oocytes disrupts chromosome alignment. EMBO Rep 2018; 19:368-381. [PMID: 29330318 PMCID: PMC5797964 DOI: 10.15252/embr.201745225] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Revised: 12/11/2017] [Accepted: 12/13/2017] [Indexed: 11/10/2022] Open
Abstract
Mitotic spindles assemble from two centrosomes, which are major microtubule-organizing centers (MTOCs) that contain centrioles. Meiotic spindles in oocytes, however, lack centrioles. In mouse oocytes, spindle microtubules are nucleated from multiple acentriolar MTOCs that are sorted and clustered prior to completion of spindle assembly in an "inside-out" mechanism, ending with establishment of the poles. We used HSET (kinesin-14) as a tool to shift meiotic spindle assembly toward a mitotic "outside-in" mode and analyzed the consequences on the fidelity of the division. We show that HSET levels must be tightly gated in meiosis I and that even slight overexpression of HSET forces spindle morphogenesis to become more mitotic-like: rapid spindle bipolarization and pole assembly coupled with focused poles. The unusual length of meiosis I is not sufficient to correct these early spindle morphogenesis defects, resulting in severe chromosome alignment abnormalities. Thus, the unique "inside-out" mechanism of meiotic spindle assembly is essential to prevent chromosomal misalignment and production of aneuploidy gametes.
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Affiliation(s)
- Isma Bennabi
- Center for Interdisciplinary Research in Biology (CIRB) College de France, CNRS, INSERM, PSL Research University, Equipe labellisée FRM, Paris, France
| | - Isabelle Quéguiner
- Center for Interdisciplinary Research in Biology (CIRB) College de France, CNRS, INSERM, PSL Research University, Equipe labellisée FRM, Paris, France
| | - Agnieszka Kolano
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Thomas Boudier
- Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Philippe Mailly
- Center for Interdisciplinary Research in Biology (CIRB) College de France, CNRS, INSERM, PSL Research University, Equipe labellisée FRM, Paris, France
| | - Marie-Hélène Verlhac
- Center for Interdisciplinary Research in Biology (CIRB) College de France, CNRS, INSERM, PSL Research University, Equipe labellisée FRM, Paris, France
| | - Marie-Emilie Terret
- Center for Interdisciplinary Research in Biology (CIRB) College de France, CNRS, INSERM, PSL Research University, Equipe labellisée FRM, Paris, France
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21
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Nakagawa S, FitzHarris G. Quantitative Microinjection of Morpholino Antisense Oligonucleotides into Mouse Oocytes to Examine Gene Function in Meiosis-I. Methods Mol Biol 2018; 1457:217-30. [PMID: 27557584 DOI: 10.1007/978-1-4939-3795-0_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Specific protein depletion is a powerful approach for assessing individual gene function in cellular processes, and has been extensively employed in recent years in mammalian oocyte meiosis-I. Conditional knockout mice and RNA interference (RNAi) methods such as siRNA or dsRNA microinjection are among several approaches to have been applied in this system over the past decade. RNAi by microinjection of Morpholino antisense Oligonucleotides (MO), in particular, has proven highly popular and tractable in many studies, since MOs have high specificity of interaction, low cell toxicity, and are more stable than other microinjected RNAi molecules. Here, we describe a method of MO microinjection into the mouse germinal vesicle-stage (GV) oocyte followed by a simple immunofluorescence approach for examination of gene function in meiosis-I.
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Affiliation(s)
- Shoma Nakagawa
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, 900 Rue St. Denis, Montreal, QC, Canada, H2X 0A9
| | - Greg FitzHarris
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, 900 Rue St. Denis, Montreal, QC, Canada, H2X 0A9. .,Department of Obstetrics and Gynecology, Université de Montréal, 3175, Ch. Côte-Sainte-Catherine, Montréal, QC, Canada, H3T 1C5.
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22
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Vázquez-Diez C, FitzHarris G. Causes and consequences of chromosome segregation error in preimplantation embryos. Reproduction 2018; 155:R63-R76. [DOI: 10.1530/rep-17-0569] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/19/2017] [Accepted: 11/06/2017] [Indexed: 01/04/2023]
Abstract
Errors in chromosome segregation are common during the mitotic divisions of preimplantation development in mammalian embryos, giving rise to so-called ‘mosaic’ embryos possessing a mixture of euploid and aneuploid cells. Mosaicism is widely considered to be detrimental to embryo quality and is frequently used as criteria to select embryos for transfer in human fertility clinics. However, despite the clear clinical importance, the underlying defects in cell division that result in mosaic aneuploidy remain elusive. In this review, we summarise recent findings from clinical and animal model studies that provide new insights into the fundamental mechanisms of chromosome segregation in the highly unusual cellular environment of early preimplantation development and consider recent clues as to why errors should commonly occur in this setting. We furthermore discuss recent evidence suggesting that mosaicism is not an irrevocable barrier to a healthy pregnancy. Understanding the causes and biological impacts of mosaic aneuploidy will be pivotal in the development and fine-tuning of clinical embryo selection methods.
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23
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Zhang QH, Yuen WS, Adhikari D, Flegg JA, FitzHarris G, Conti M, Sicinski P, Nabti I, Marangos P, Carroll J. Cyclin A2 modulates kinetochore-microtubule attachment in meiosis II. J Cell Biol 2017; 216:3133-3143. [PMID: 28819014 PMCID: PMC5626527 DOI: 10.1083/jcb.201607111] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 07/04/2017] [Accepted: 07/28/2017] [Indexed: 12/17/2022] Open
Abstract
Cyclin A2 is a crucial mitotic Cdk regulatory partner that coordinates entry into mitosis and is then destroyed in prometaphase within minutes of nuclear envelope breakdown. The role of cyclin A2 in female meiosis and its dynamics during the transition from meiosis I (MI) to meiosis II (MII) remain unclear. We found that cyclin A2 decreases in prometaphase I but recovers after the first meiotic division and persists, uniquely for metaphase, in MII-arrested oocytes. Conditional deletion of cyclin A2 from mouse oocytes has no discernible effect on MI but leads to disrupted MII spindles and increased merotelic attachments. On stimulation of exit from MII, there is a dramatic increase in lagging chromosomes and an inhibition of cytokinesis. These defects are associated with an increase in microtubule stability in MII spindles, suggesting that cyclin A2 mediates the fidelity of MII by maintaining microtubule dynamics during the rapid formation of the MII spindle.
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Affiliation(s)
- Qing-Hua Zhang
- Development and Stem Cell Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia .,Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Wai Shan Yuen
- Development and Stem Cell Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Deepak Adhikari
- Development and Stem Cell Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Jennifer A Flegg
- Monash Academy for Cross and Interdisciplinary Mathematical Applications, Monash University, Melbourne, Victoria, Australia
| | - Greg FitzHarris
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada.,Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada
| | - Marco Conti
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, CA
| | - Piotr Sicinski
- Dana-Farber Cancer Institute, Boston, MA.,Department of Genetics, Harvard Medical School, Boston, MA
| | - Ibtissem Nabti
- Department of Cell and Developmental Biology, University College London, London, England, UK.,Division of Science, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Petros Marangos
- Department of Cell and Developmental Biology, University College London, London, England, UK.,Department of Biological Applications and Technology, University of Ioannina, Ioannina, Greece.,Department of Biomedical Research, Institute of Molecular Biology and Biotechnology-Foundation for Research and Technology, Ioannina, Greece
| | - John Carroll
- Development and Stem Cell Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia .,Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia.,Department of Cell and Developmental Biology, University College London, London, England, UK
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24
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Chaigne A, Terret ME, Verlhac MH. Asymmetries and Symmetries in the Mouse Oocyte and Zygote. Results Probl Cell Differ 2017; 61:285-299. [PMID: 28409310 DOI: 10.1007/978-3-319-53150-2_13] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mammalian oocytes grow periodically after puberty thanks to the dialogue with their niche in the follicle. This communication between somatic and germ cells promotes the accumulation, inside the oocyte, of maternal RNAs, proteins and other molecules that will sustain the two gamete divisions and early embryo development up to its implantation. In order to preserve their stock of maternal products, oocytes from all species divide twice minimizing the volume of their daughter cells to their own benefit. For this, they undergo asymmetric divisions in size where one main objective is to locate the division spindle with its chromosomes off-centred. In this chapter, we will review how this main objective is reached with an emphasis on the role of actin microfilaments in this process in mouse oocytes, the most studied example in mammals. This chapter is subdivided into three parts: I-General features of asymmetric divisions in mouse oocytes, II-Mechanism of chromosome positioning by actin in mouse oocytes and III-Switch from asymmetric to symmetric division at the oocyte-to-embryo transition.
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Affiliation(s)
- Agathe Chaigne
- MRC Laboratory for Molecular Cell Biology, UCL, London, WC1E 6BT, UK.,Institute for the Physics of Living Systems, UCL, London, WC1E 6BT, UK
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25
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Bennabi I, Terret ME, Verlhac MH. Meiotic spindle assembly and chromosome segregation in oocytes. J Cell Biol 2016; 215:611-619. [PMID: 27879467 PMCID: PMC5147004 DOI: 10.1083/jcb.201607062] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/10/2016] [Accepted: 11/02/2016] [Indexed: 11/22/2022] Open
Abstract
Centrosomes play a key role in organizing the microtubule spindle that separates chromosomes during mitosis. Bennabi et al. review how microtubule spindle formation and chromosomal segregation also occur in oocytes during cell division by meiosis despite the absence of centrosomes. Oocytes accumulate maternal stores (proteins, mRNAs, metabolites, etc.) during their growth in the ovary to support development after fertilization. To preserve this cytoplasmic maternal inheritance, they accomplish the difficult task of partitioning their cytoplasm unequally while dividing their chromosomes equally. Added to this complexity, most oocytes, for reasons still speculative, lack the major microtubule organizing centers that most cells use to assemble and position their spindles, namely canonical centrosomes. In this review, we will address recent work on the mechanisms of meiotic spindle assembly and chromosome alignment/segregation in female gametes to try to understand the origin of errors of oocyte meiotic divisions. The challenge of oocyte divisions appears indeed not trivial because in both mice and humans oocyte meiotic divisions are prone to chromosome segregation errors, a leading cause of frequent miscarriages and congenital defects.
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Affiliation(s)
- Isma Bennabi
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
| | - Marie-Emilie Terret
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
| | - Marie-Hélène Verlhac
- Centre for Interdisciplinary Research in Biology, Collège de France, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, PSL Research University, Paris 75006, France
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26
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Kong XW, Wang DH, Zhou CJ, Zhou HX, Liang CG. Loss of function of KIF1B impairs oocyte meiotic maturation and early embryonic development in mice. Mol Reprod Dev 2016; 83:1027-1040. [PMID: 27696585 DOI: 10.1002/mrd.22744] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 09/14/2016] [Indexed: 02/05/2023]
Abstract
Kinesin family member 1B (KIF1B) is an important microtubule-dependent monomeric motor in mammals, although little is known about its role in meiosis. We profiled KIF1B expression and localization during oocyte maturation and early embryonic development in mice, revealing a dynamic pattern throughout meiotic progression. Depletion or inhibition of KIF1B leads to abnormal polar body extrusion, disordered spindle dynamics, defects in chromosome congression, increased aneuploidy, and impaired embryonic development. Further, KIF1B depletion affects the distribution of mitochondria and abundance of ATP. Taken together, our study demonstrates that mouse KIF1B is important for spindle assembly, chromosome congression, and mitochondrial distribution during oocyte maturation and early embryonic development. Mol. Reprod. Dev. 83: 1027-1040, 2016 © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Xiang-Wei Kong
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Dong-Hui Wang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Cheng-Jie Zhou
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Hong-Xia Zhou
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
| | - Cheng-Guang Liang
- The Key Laboratory of National Education Ministry for Mammalian Reproductive Biology and Biotechnology, The Research Center for Laboratory Animal Science, College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia, People's Republic of China
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Ko CI, Fan Y, de Gannes M, Wang Q, Xia Y, Puga A. Repression of the Aryl Hydrocarbon Receptor Is Required to Maintain Mitotic Progression and Prevent Loss of Pluripotency of Embryonic Stem Cells. Stem Cells 2016; 34:2825-2839. [DOI: 10.1002/stem.2456] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Chia-I Ko
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
| | - Yunxia Fan
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
| | - Matthew de Gannes
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
| | - Qin Wang
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
| | - Ying Xia
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics; University of Cincinnati College of Medicine; Cincinnati Ohio USA
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28
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Bury L, Coelho PA, Glover DM. From Meiosis to Mitosis: The Astonishing Flexibility of Cell Division Mechanisms in Early Mammalian Development. Curr Top Dev Biol 2016; 120:125-71. [PMID: 27475851 DOI: 10.1016/bs.ctdb.2016.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The execution of female meiosis and the establishment of the zygote is arguably the most critical stage of mammalian development. The egg can be arrested in the prophase of meiosis I for decades, and when it is activated, the spindle is assembled de novo. This spindle must function with the highest of fidelity and yet its assembly is unusually achieved in the absence of conventional centrosomes and with minimal influence of chromatin. Moreover, its dramatic asymmetric positioning is achieved through remarkable properties of the actin cytoskeleton to ensure elimination of the polar bodies. The second meiotic arrest marks a uniquely prolonged metaphase eventually interrupted by egg activation at fertilization to complete meiosis and mark a period of preparation of the male and female pronuclear genomes not only for their entry into the mitotic cleavage divisions but also for the imminent prospect of their zygotic expression.
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Affiliation(s)
- L Bury
- University of Cambridge, Cambridge, United Kingdom.
| | - P A Coelho
- University of Cambridge, Cambridge, United Kingdom
| | - D M Glover
- University of Cambridge, Cambridge, United Kingdom
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29
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Nucleus downscaling in mouse embryos is regulated by cooperative developmental and geometric programs. Sci Rep 2016; 6:28040. [PMID: 27320842 PMCID: PMC4913252 DOI: 10.1038/srep28040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 05/24/2016] [Indexed: 11/27/2022] Open
Abstract
Maintaining appropriate nucleus size is important for cell health, but the mechanisms by which this is achieved are poorly understood. Controlling nucleus size is a particular challenge in early development, where the nucleus must downscale in size with progressive reductive cell divisions. Here we use live and fixed imaging, micromanipulation approaches, and small molecule analyses during preimplantation mouse development to probe the mechanisms by which nucleus size is determined. We find a close correlation between cell and nuclear size at any given developmental stage, and show that experimental cytoplasmic reduction can alter nuclear size, together indicating that cell size helps dictate nuclear proportions. Additionally, however, by creating embryos with over-sized blastomeres we present evidence of a developmental program that drives nuclear downscaling independently of cell size. We show that this developmental program does not correspond with nuclear import rates, but provide evidence that PKC activity may contribute to this mechanism. We propose a model in which nuclear size regulation during early development is a multi-mode process wherein nucleus size is set by cytoplasmic factors, and fine-tuned on a cell-by-cell basis according to cell size.
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30
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Haverfield J, Nakagawa S, Love D, Tsichlaki E, Nomikos M, Lai FA, Swann K, FitzHarris G. Ca(2+) dynamics in oocytes from naturally-aged mice. Sci Rep 2016; 6:19357. [PMID: 26785810 PMCID: PMC4726220 DOI: 10.1038/srep19357] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/11/2015] [Indexed: 12/18/2022] Open
Abstract
The ability of human metaphase-II arrested eggs to activate following fertilisation declines with advancing maternal age. Egg activation is triggered by repetitive increases in intracellular Ca2+ concentration ([Ca2+]i) in the ooplasm as a result of sperm-egg fusion. We therefore hypothesised that eggs from older females feature a reduced ability to mount appropriate Ca2+ responses at fertilisation. To test this hypothesis we performed the first examination of Ca2+ dynamics in eggs from young and naturally-aged mice. Strikingly, we find that Ca2+ stores and resting [Ca2+]i are unchanged with age. Although eggs from aged mice feature a reduced ability to replenish intracellular Ca2+ stores following depletion, this difference had no effect on the duration, number, or amplitude of Ca2+ oscillations following intracytoplasmic sperm injection or expression of phospholipase C zeta. In contrast, we describe a substantial reduction in the frequency and duration of oscillations in aged eggs upon parthenogenetic activation with SrCl2. We conclude that the ability to mount and respond to an appropriate Ca2+ signal at fertilisation is largely unchanged by advancing maternal age, but subtle changes in Ca2+ handling occur that may have more substantial impacts upon commonly used means of parthenogenetic activation.
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Affiliation(s)
- Jenna Haverfield
- Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9.,Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada, H3T 1J4
| | - Shoma Nakagawa
- Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9
| | - Daniel Love
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN
| | - Elina Tsichlaki
- Department of Cell and Developmental Biology, University College London, London, UK, WC1E 6BT
| | - Michail Nomikos
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN
| | - F Anthony Lai
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN
| | - Karl Swann
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, UK, CF14 4XN
| | - Greg FitzHarris
- Centre Recherche Centre Hospitalier Université de Montréal, Montreal, Québec, Canada, H2X 0A9.,Department of Obstetrics and Gynaecology, University of Montréal, Montréal, Québec, Canada, H3T 1J4.,Department of Cell and Developmental Biology, University College London, London, UK, WC1E 6BT
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31
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Micronucleus formation causes perpetual unilateral chromosome inheritance in mouse embryos. Proc Natl Acad Sci U S A 2016; 113:626-31. [PMID: 26729872 DOI: 10.1073/pnas.1517628112] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromosome segregation defects in cancer cells lead to encapsulation of chromosomes in micronuclei (MN), small nucleus-like structures within which dangerous DNA rearrangements termed chromothripsis can occur. Here we uncover a strikingly different consequence of MN formation in preimplantation development. We find that chromosomes from within MN become damaged and fail to support a functional kinetochore. MN are therefore not segregated, but are instead inherited by one of the two daughter cells. We find that the same MN can be inherited several times without rejoining the principal nucleus and without altering the kinetics of cell divisions. MN motion is passive, resulting in an even distribution of MN across the first two cell lineages. We propose that perpetual unilateral MN inheritance constitutes an unexpected mode of chromosome missegregation, which could contribute to the high frequency of aneuploid cells in mammalian embryos, but simultaneously may serve to insulate the early embryonic genome from chromothripsis.
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Abstract
A metaphase spindle is a complex structure consisting of microtubules and a myriad of different proteins that modulate microtubule dynamics together with chromatin and kinetochores. A decade ago, a full description of spindle formation and function seemed a lofty goal. Here, we describe how work in the last 10 years combining cataloging of spindle components, the characterization of their biochemical activities using single-molecule techniques, and theory have advanced our knowledge. Taken together, these advances suggest that a full understanding of spindle assembly and function may soon be possible.
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Affiliation(s)
- Simone Reber
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany Integrative Research Institute (IRI) for the Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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Helmke KJ, Heald R. TPX2 levels modulate meiotic spindle size and architecture in Xenopus egg extracts. ACTA ACUST UNITED AC 2014; 206:385-93. [PMID: 25070954 PMCID: PMC4121975 DOI: 10.1083/jcb.201401014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
TPX2 levels modulate spindle architecture through Eg5, partitioning microtubules between a tiled, antiparallel array that promotes spindle expansion and a cross-linked, parallel architecture that concentrates microtubules at spindle poles. The spindle segregates chromosomes in dividing eukaryotic cells, and its assembly pathway and morphology vary across organisms and cell types. We investigated mechanisms underlying differences between meiotic spindles formed in egg extracts of two frog species. Small Xenopus tropicalis spindles resisted inhibition of two factors essential for assembly of the larger Xenopus laevis spindles: RanGTP, which functions in chromatin-driven spindle assembly, and the kinesin-5 motor Eg5, which drives antiparallel microtubule (MT) sliding. This suggested a role for the MT-associated protein TPX2 (targeting factor for Xenopus kinesin-like protein 2), which is regulated by Ran and binds Eg5. Indeed, TPX2 was threefold more abundant in X. tropicalis extracts, and elevated TPX2 levels in X. laevis extracts reduced spindle length and sensitivity to Ran and Eg5 inhibition. Higher TPX2 levels recruited Eg5 to the poles, where MT density increased. We propose that TPX2 levels modulate spindle architecture through Eg5, partitioning MTs between a tiled, antiparallel array that promotes spindle expansion and a cross-linked, parallel architecture that concentrates MTs at spindle poles.
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Affiliation(s)
- Kara J Helmke
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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34
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Howe K, FitzHarris G. Recent insights into spindle function in mammalian oocytes and early embryos. Biol Reprod 2013; 89:71. [PMID: 23966320 DOI: 10.1095/biolreprod.113.112151] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Errors in chromosome segregation in oocytes and early embryos lead to embryo aneuploidy, which contributes to early pregnancy loss. At the heart of chromosome segregation is the spindle, a dynamic biomechanical machine fashioned from microtubules, which is tasked with gathering and sorting chromosomes and dispatching them to the daughter cells at the time of cell division. Understanding the causes of segregation error in the oocyte and early embryo will undoubtedly hinge on a thorough understanding of the mechanism of spindle assembly and function in these highly specialized cellular environments. The recent advent of live imaging approaches to observe chromosome segregation in real-time in oocytes and embryos, paired with gene-silencing techniques and specific inhibition for assessing the function of a protein of interest, has led to a substantial advance in our understanding of chromosome segregation in early mammalian development. These studies have uncovered numerous mechanistic differences between oocytes, embryos, and traditional model systems. In addition, a flurry of recent studies using naturally aged mice as the model for human aging have begun to shed light on the increased levels of aneuploidy seen in embryos from older mothers. Here we review these recent developments and consider what has been learned about the causes of chromosome missegregation in early development.
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Affiliation(s)
- Katie Howe
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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35
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Clift D, Schuh M. Restarting life: fertilization and the transition from meiosis to mitosis. Nat Rev Mol Cell Biol 2013; 14:549-62. [PMID: 23942453 PMCID: PMC4021448 DOI: 10.1038/nrm3643] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Fertilization triggers a complex cellular programme that transforms two highly specialized meiotic germ cells, the oocyte and the sperm, into a totipotent mitotic embryo. Linkages between sister chromatids are remodelled to support the switch from reductional meiotic to equational mitotic divisions; the centrosome, which is absent from the egg, is reintroduced; cell division shifts from being extremely asymmetric to symmetric; genomic imprinting is selectively erased and re-established; and protein expression shifts from translational control to transcriptional control. Recent work has started to reveal how this remarkable transition from meiosis to mitosis is achieved.
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Affiliation(s)
- Dean Clift
- Medical Research Council Laboratory of Molecular Biology (MRC LMB), Cambridge CB2 0QH, UK
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36
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Howe K, FitzHarris G. A non-canonical mode of microtubule organization operates throughout pre-implantation development in mouse. Cell Cycle 2013; 12:1616-24. [PMID: 23624836 DOI: 10.4161/cc.24755] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In dividing animal cells, the centrosome, comprising centrioles and surrounding pericentriolar-material (PCM), is the major interphase microtubule-organizing center (MTOC), arranging a polarized array of microtubules (MTs) that controls cellular architecture. The mouse embryo is a unique setting for investigating the role of centrosomes in MT organization, since the early embryo is acentrosomal, and centrosomes emerge de novo during early cleavages. Here we use embryos from a GFP::CETN2 transgenic mouse to observe the emergence of centrosomes and centrioles in embryos, and show that unfocused acentriolar centrosomes first form in morulae (~16-32-cell stage) and become focused at the blastocyst stage (~64-128 cells) concomitant with the emergence of centrioles. We then used high-resolution microscopy and dynamic tracking of MT growth events in live embryos to examine the impact of centrosome emergence upon interphase MT dynamics. We report that pre-implantation mouse embryos of all stages employ a non-canonical mode of MT organization that generates a complex array of randomly oriented MTs that are preferentially nucleated adjacent to nuclear and plasmalemmal membranes and cell-cell interfaces. Surprisingly, however, cells of the early embryo continue to employ this mode of interphase MT organization even after the emergence of centrosomes. Centrosomes are found at MT-sparse sites and have no detectable impact upon interphase MT dynamics. To our knowledge, the early embryo is unique among proliferating cells in adopting an acentrosomal mode of MT organization despite the presence of centrosomes, revealing that the transition to a canonical mode of interphase MT organization remains incomplete prior to implantation.
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Affiliation(s)
- Katie Howe
- Department of Cell and Developmental Biology, University College London, London, UK
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37
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Goulet A, Moores C. New insights into the mechanism of force generation by kinesin-5 molecular motors. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:419-66. [PMID: 23809441 DOI: 10.1016/b978-0-12-407696-9.00008-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kinesin-5 motors are members of a superfamily of microtubule-dependent ATPases and are widely conserved among eukaryotes. Kinesin-5s typically form homotetramers with pairs of motor domains located at either end of a dumbbell-shaped molecule. This quaternary structure enables cross-linking and ATP-driven sliding of pairs of microtubules, although the exact molecular mechanism of this activity is still unclear. Kinesin-5 function has been characterized in greatest detail in cell division, although a number of interphase roles have also been defined. The kinesin-5 ATPase is tuned for slow microtubule sliding rather than cellular transport and-in vertebrates-can be inhibited specifically by allosteric small molecules currently in cancer clinical trials. The biophysical and structural basis of kinesin-5 mechanochemistry is being elucidated and has provided further insight into kinesin-5 activities. However, it is likely that the precise mechanism of these important motors has evolved according to functional context and regulation in individual organisms.
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Affiliation(s)
- Adeline Goulet
- Institute of Structural and Molecular Biology, Birkbeck College, London, United Kingdom
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38
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Yamagata K, FitzHarris G. 4D imaging reveals a shift in chromosome segregation dynamics during mouse pre-implantation development. Cell Cycle 2012; 12:157-65. [PMID: 23255117 DOI: 10.4161/cc.23052] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cells of the early developing mammalian embryo frequently mis-segregate chromosomes during cell division, causing daughter cells to inherit an erroneous numbers of chromosomes. Why the embryo is so susceptible to errors is unknown, and the mechanisms that embryos employ to accomplish chromosome segregation are poorly understood. Chromosome segregation is performed by the spindle, a fusiform-shaped microtubule-based transient organelle. Here we present a detailed analysis of 4D fluorescence-confocal data sets of live embryos progressing from the one-cell embryo stage through to blastocyst in vitro, providing some of the first mechanistic insights into chromosome segregation in the mammalian embryo. We show that chromosome segregation occurs as a combined result of poleward chromosome motion (anaphase-A) and spindle elongation (anaphase-B), which occur simultaneously at the time of cell division. Unexpectedly, however, regulation of the two anaphase mechanisms changes significantly between the first and second embryonic mitoses. In one-cell embryos, the velocity of anaphase-A chromosome motion and the velocity and overall extent of anaphase-B spindle elongation are significantly constrained compared with later stages. As a result chromosomes are delivered close to the center of the forming two-cell stage blastomeres at the end of the first mitosis. In subsequent divisions, anaphase-B spindle elongation is faster and more extensive, resulting in the delivery of chromosomes to the distal plasma membrane of the newly forming blastomeres. Metaphase spindle length scales with cell size from the two-cell stage onwards, but is substantially shorter in the first mitosis than in the second mitosis, and the duration of mitosis-1 is substantially greater than subsequent divisions. Thus, there is a striking and unexpected shift in the approach to cell division between the first and second mitotic divisions, which likely reflects adaptations to the unique environment within the developing embryo.
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Affiliation(s)
- Kazuo Yamagata
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
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39
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Holt JE, Lane SIR, Jennings P, García-Higuera I, Moreno S, Jones KT. APC(FZR1) prevents nondisjunction in mouse oocytes by controlling meiotic spindle assembly timing. Mol Biol Cell 2012; 23:3970-81. [PMID: 22918942 PMCID: PMC3469513 DOI: 10.1091/mbc.e12-05-0352] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The APC activator FZR1 has a role in controlling the timing of meiosis I spindle assembly. Oocytes lacking FZR1 undergo accelerated meiosis I, associated with earlier spindle assembly checkpoint satisfaction and APCCDC20 activity, resulting in high rates of aneuploidy. FZR1 is an anaphase-promoting complex (APC) activator best known for its role in the mitotic cell cycle at M-phase exit, in G1, and in maintaining genome integrity. Previous studies also established that it prevents meiotic resumption, equivalent to the G2/M transition. Here we report that mouse oocytes lacking FZR1 undergo passage through meiosis I that is accelerated by ∼1 h, and this is due to an earlier onset of spindle assembly checkpoint (SAC) satisfaction and APCCDC20 activity. However, loss of FZR1 did not compromise SAC functionality; instead, earlier SAC satisfaction was achieved because the bipolar meiotic spindle was assembled more quickly in the absence of FZR1. This novel regulation of spindle assembly by FZR1 led to premature bivalent attachment to microtubules and loss of kinetochore-bound MAD2. Bivalents, however, were observed to congress poorly, leading to nondisjunction rates of 25%. We conclude that in mouse oocytes FZR1 controls the timing of assembly of the bipolar spindle and in so doing the timing of SAC satisfaction and APCCDC20 activity. This study implicates FZR1 as a major regulator of prometaphase whose activity helps to prevent chromosome nondisjunction.
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Affiliation(s)
- Janet E Holt
- School of Biomedical Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.
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40
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Courtois A, Schuh M, Ellenberg J, Hiiragi T. The transition from meiotic to mitotic spindle assembly is gradual during early mammalian development. ACTA ACUST UNITED AC 2012; 198:357-70. [PMID: 22851319 PMCID: PMC3413348 DOI: 10.1083/jcb.201202135] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The transition from a meiotic-like spindle formation characterized by lack of centrioles to a typical mitotic spindle occurs gradually in embryos during the preimplantation stage. The transition from meiosis to mitosis, classically defined by fertilization, is a fundamental process in development. However, its mechanism remains largely unexplored. In this paper, we report a surprising gradual transition from meiosis to mitosis over the first eight divisions of the mouse embryo. The first cleavages still largely share the mechanism of spindle formation with meiosis, during which the spindle is self-assembled from randomly distributed microtubule-organizing centers (MTOCs) without centrioles, because of the concerted activity of dynein and kinesin-5. During preimplantation development, the number of cellular MTOCs progressively decreased, the spindle pole gradually became more focused, and spindle length progressively scaled down with cell size. The typical mitotic spindle with centrin-, odf2-, kinesin-12–, and CP110-positive centrosomes was established only in the blastocyst. Overall, the transition from meiosis to mitosis progresses gradually throughout the preimplantation stage in the mouse embryo, thus providing a unique system to study the mechanism of centrosome biogenesis in vivo.
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Affiliation(s)
- Aurélien Courtois
- Mammalian Development Laboratory, Max Planck Institute for Molecular Biomedicine, 48149 Münster, Germany
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41
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Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis. Trends Cell Biol 2012; 22:241-9. [PMID: 22480579 DOI: 10.1016/j.tcb.2012.02.007] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 11/24/2022]
Abstract
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 most 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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42
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FitzHarris G. Anaphase B precedes anaphase A in the mouse egg. Curr Biol 2012; 22:437-44. [PMID: 22342753 DOI: 10.1016/j.cub.2012.01.041] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/14/2012] [Accepted: 01/20/2012] [Indexed: 11/29/2022]
Abstract
Segregation of chromosomes at the time of cell division is achieved by the microtubules and associated molecules of the spindle. Chromosomes attach to kinetochore microtubules (kMTs), which extend from the spindle pole region to kinetochores assembled upon centromeric DNA. In most animal cells studied, chromosome segregation occurs as a result of kMT shortening, which causes chromosomes to move toward the spindle poles (anaphase A). Anaphase A is typically followed by a spindle elongation that further separates the chromosomes (anaphase B). The experiments presented here provide the first detailed analysis of anaphase in a live vertebrate oocyte and show that chromosome segregation is initially driven by a significant spindle elongation (anaphase B), which is followed by a shortening of kMTs to fully segregate the chromosomes (anaphase A). Loss of tension across kMTs at anaphase onset produces a force imbalance, allowing the bipolar motor kinesin-5 to drive early anaphase B spindle elongation and chromosome segregation. Early anaphase B spindle elongation determines the extent of chromosome segregation and the size of the resulting cells. The vertebrate egg therefore employs a novel mode of anaphase wherein spindle elongation caused by loss of k-fiber tension is harnessed to kick-start chromosome segregation prior to anaphase A.
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Affiliation(s)
- Greg FitzHarris
- University College London Institute for Women's Health, 86-96 Chenies Mews, London WC1E 6HX, UK.
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43
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Courtois A, Hiiragi T. Gradual meiosis-to-mitosis transition in the early mouse embryo. Results Probl Cell Differ 2012; 55:107-14. [PMID: 22918803 DOI: 10.1007/978-3-642-30406-4_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The transition from meiosis to mitosis is a fundamental process to guarantee the successful development of the embryo. In the mouse, the transition includes extensive reorganisation of the division machinery, centrosome establishment and changes in spindle proprieties and characteristic. Recent findings indicate that this transition is gradual and lasts until the late blastocyst stage. In-depth knowledge of the mechanisms underlying the transition would provide new insight into de novo centrosome formation and regulation of spindle size and proprieties. Here, we review recent advances in the understanding of acentrosomal spindle formation, centriole establishment and the meiosis-to-mitosis transition in the mouse pre-implantation embryo.
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44
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Breuer M, Kolano A, Kwon M, Li CC, Tsai TF, Pellman D, Brunet S, Verlhac MH. HURP permits MTOC sorting for robust meiotic spindle bipolarity, similar to extra centrosome clustering in cancer cells. ACTA ACUST UNITED AC 2010; 191:1251-60. [PMID: 21173113 PMCID: PMC3010075 DOI: 10.1083/jcb.201005065] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In contrast to somatic cells, formation of acentriolar meiotic spindles relies on the organization of microtubules (MTs) and MT-organizing centers (MTOCs) into a stable bipolar structure. The underlying mechanisms are still unknown. We show that this process is impaired in hepatoma up-regulated protein (Hurp) knockout mice, which are viable but female sterile, showing defective oocyte divisions. HURP accumulates on interpolar MTs in the vicinity of chromosomes via Kinesin-5 activity. By promoting MT stability in the spindle central domain, HURP allows efficient MTOC sorting into distinct poles, providing bipolarity establishment and maintenance. Our results support a new model for meiotic spindle assembly in which HURP ensures assembly of a central MT array, which serves as a scaffold for the genesis of a robust bipolar structure supporting efficient chromosome congression. Furthermore, HURP is also required for the clustering of extra centrosomes before division, arguing for a shared molecular requirement of MTOC sorting in mammalian meiosis and cancer cell division.
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Affiliation(s)
- Manuel Breuer
- Unité Mixte de Recherche 7622, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, 75005 Paris, France
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Illingworth C, Pirmadjid N, Serhal P, Howe K, Fitzharris G. MCAK regulates chromosome alignment but is not necessary for preventing aneuploidy in mouse oocyte meiosis I. Development 2010. [PMID: 20504960 DOI: 10.1242/dev.048306%jdevelopment] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
Errors in chromosome segregation in mammalian oocytes lead to aneuploid eggs that are developmentally compromised. In mitotic cells, mitotic centromere associated kinesin (MCAK; KIF2C) prevents chromosome segregation errors by detaching incorrect microtubule-kinetochore interactions. Here, we examine whether MCAK is involved in spindle function in mouse oocyte meiosis I, and whether MCAK is necessary to prevent chromosome segregation errors. We find that MCAK is recruited to centromeres, kinetochores and chromosome arms in mid-meiosis I, and that MCAK depletion, or inhibition using a dominant-negative construct, causes chromosome misalignment. However, the majority of oocytes complete meiosis I and the resulting eggs retain the correct number of chromosomes. Moreover, MCAK-depleted oocytes can recover from mono-orientation of homologous kinetochores in mid-meiosis I to segregate chromosomes correctly. Thus, MCAK contributes to chromosome alignment in meiosis I, but is not necessary for preventing chromosome segregation errors. Although other correction mechanisms may function in mammalian meiosis I, we speculate that late establishment of kinetochore microtubules in oocytes reduces the likelihood of incorrect microtubule-kinetochore interactions, bypassing the requirement for error correction.
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Affiliation(s)
- Crista Illingworth
- University College London Institute for Women's Health, 86-96 Chenies Mews, London WC1E6HX, UK
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Illingworth C, Pirmadjid N, Serhal P, Howe K, Fitzharris G. MCAK regulates chromosome alignment but is not necessary for preventing aneuploidy in mouse oocyte meiosis I. Development 2010; 137:2133-8. [PMID: 20504960 DOI: 10.1242/dev.048306] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Errors in chromosome segregation in mammalian oocytes lead to aneuploid eggs that are developmentally compromised. In mitotic cells, mitotic centromere associated kinesin (MCAK; KIF2C) prevents chromosome segregation errors by detaching incorrect microtubule-kinetochore interactions. Here, we examine whether MCAK is involved in spindle function in mouse oocyte meiosis I, and whether MCAK is necessary to prevent chromosome segregation errors. We find that MCAK is recruited to centromeres, kinetochores and chromosome arms in mid-meiosis I, and that MCAK depletion, or inhibition using a dominant-negative construct, causes chromosome misalignment. However, the majority of oocytes complete meiosis I and the resulting eggs retain the correct number of chromosomes. Moreover, MCAK-depleted oocytes can recover from mono-orientation of homologous kinetochores in mid-meiosis I to segregate chromosomes correctly. Thus, MCAK contributes to chromosome alignment in meiosis I, but is not necessary for preventing chromosome segregation errors. Although other correction mechanisms may function in mammalian meiosis I, we speculate that late establishment of kinetochore microtubules in oocytes reduces the likelihood of incorrect microtubule-kinetochore interactions, bypassing the requirement for error correction.
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Affiliation(s)
- Crista Illingworth
- University College London Institute for Women's Health, 86-96 Chenies Mews, London WC1E6HX, UK
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