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Zhu F, Yang M, Wang D, Jiang Y, Jia C, Fu Y, Yu A, Liu H, Wang M, Wang T, Liu H, Li J. Spatial distribution of maternal factors in pig mature oocytes. Anim Biotechnol 2024; 35:2394692. [PMID: 39185998 DOI: 10.1080/10495398.2024.2394692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 08/15/2024] [Indexed: 08/27/2024]
Abstract
It is known that asymmetrical maternal transcripts play an important role in the cell fate of the early embryo, but few studies are available in mammal oocytes especially in pig. To investigate the spatial factors in pig oocytes, the oriented bisection was established for collecting karyoplasts (NSOs) and cytoplasts (SSOs) with more than 95% efficiency. Subsequently, RNA-Seq and LC-MS/MS analysis were performed on NSOs and SSOs. Although no differentially expressed genes (DEGs) could be detected between NSOs and SSOs, 89 of the differentially expressed proteins (DEPs) were detected, that 58 proteins higher expressed but 31 proteins lower expressed in NSOs compared with SSOs. These DEPs mainly participated in the 'cell cycle' and 'ribosome' pathway, while the up-regulated DEPs were mainly GO in 'spindle' and 'positive regulation of translation', and the down-regulated DEPs were in 'cytosolic small ribosomal subunit' and 'mRNA binding'. The up-regulated DEP SIRT5 which are related to the regulation of gene expression, epigenetic were further detected and revealed. A spatial asymmetry of maternal factors at the protein level was firstly detected in pig mature oocytes.
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Affiliation(s)
- Fuquan Zhu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Meng Yang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Dayu Wang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Yuan Jiang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Chao Jia
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Yanfeng Fu
- Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Aochen Yu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Huijun Liu
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Zhejiang Institute of Microbiology, Hangzhou, Zhejiang Province, China
| | - Meixia Wang
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Zhejiang Institute of Microbiology, Hangzhou, Zhejiang Province, China
| | - Tingzhang Wang
- Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Zhejiang Institute of Microbiology, Hangzhou, Zhejiang Province, China
| | - Honglin Liu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Juan Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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2
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Gahurova L, Tomankova J, Cerna P, Bora P, Kubickova M, Virnicchi G, Kovacovicova K, Potesil D, Hruska P, Zdrahal Z, Anger M, Susor A, Bruce AW. Spatial positioning of preimplantation mouse embryo cells is regulated by mTORC1 and m 7G-cap-dependent translation at the 8- to 16-cell transition. Open Biol 2023; 13:230081. [PMID: 37553074 PMCID: PMC10409569 DOI: 10.1098/rsob.230081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 07/18/2023] [Indexed: 08/10/2023] Open
Abstract
Preimplantation mouse embryo development involves temporal-spatial specification and segregation of three blastocyst cell lineages: trophectoderm, primitive endoderm and epiblast. Spatial separation of the outer-trophectoderm lineage from the two other inner-cell-mass (ICM) lineages starts with the 8- to 16-cell transition and concludes at the 32-cell stages. Accordingly, the ICM is derived from primary and secondary contributed cells; with debated relative EPI versus PrE potencies. We report generation of primary but not secondary ICM populations is highly dependent on temporal activation of mammalian target of Rapamycin (mTOR) during 8-cell stage M-phase entry, mediated via regulation of the 7-methylguanosine-cap (m7G-cap)-binding initiation complex (EIF4F) and linked to translation of mRNAs containing 5' UTR terminal oligopyrimidine (TOP-) sequence motifs, as knockdown of identified TOP-like motif transcripts impairs generation of primary ICM founders. However, mTOR inhibition-induced ICM cell number deficits in early blastocysts can be compensated by the late blastocyst stage, after inhibitor withdrawal; compensation likely initiated at the 32-cell stage when supernumerary outer cells exhibit molecular characteristics of inner cells. These data identify a novel mechanism specifically governing initial spatial segregation of mouse embryo blastomeres, that is distinct from those directing subsequent inner cell formation, contributing to germane segregation of late blastocyst lineages.
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Affiliation(s)
- Lenka Gahurova
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 27721 Liběchov, Czech Republic
| | - Jana Tomankova
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Pavlina Cerna
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Pablo Bora
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Michaela Kubickova
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Giorgio Virnicchi
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Kristina Kovacovicova
- Laboratory of Cell Division Control, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 27721 Liběchov, Czech Republic
- Department of Genetics and Reproduction, Central European Institute of Technology, Veterinary Research Institute, Hudcova 296/70, 621 00 Brno, Czech Republic
| | - David Potesil
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic
| | - Pavel Hruska
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic
| | - Zbynek Zdrahal
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, 62500 Brno, Czech Republic
| | - Martin Anger
- Laboratory of Cell Division Control, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 27721 Liběchov, Czech Republic
- Department of Genetics and Reproduction, Central European Institute of Technology, Veterinary Research Institute, Hudcova 296/70, 621 00 Brno, Czech Republic
| | - Andrej Susor
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 27721 Liběchov, Czech Republic
| | - Alexander W. Bruce
- Laboratory of Early Mammalian Developmental Biology (LEMDB), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
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3
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Jiang Y, Adhikari D, Li C, Zhou X. Spatiotemporal regulation of maternal mRNAs during vertebrate oocyte meiotic maturation. Biol Rev Camb Philos Soc 2023; 98:900-930. [PMID: 36718948 DOI: 10.1111/brv.12937] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 01/15/2023] [Accepted: 01/17/2023] [Indexed: 02/01/2023]
Abstract
Vertebrate oocytes face a particular challenge concerning the regulation of gene expression during meiotic maturation. Global transcription becomes quiescent in fully grown oocytes, remains halted throughout maturation and fertilization, and only resumes upon embryonic genome activation. Hence, the oocyte meiotic maturation process is largely regulated by protein synthesis from pre-existing maternal messenger RNAs (mRNAs) that are transcribed and stored during oocyte growth. Rapidly developing genome-wide techniques have greatly expanded our insights into the global translation changes and possible regulatory mechanisms during oocyte maturation. The storage, translation, and processing of maternal mRNAs are thought to be regulated by factors interacting with elements in the mRNA molecules. Additionally, posttranscriptional modifications of mRNAs, such as methylation and uridylation, have recently been demonstrated to play crucial roles in maternal mRNA destabilization. However, a comprehensive understanding of the machineries that regulate maternal mRNA fate during oocyte maturation is still lacking. In particular, how the transcripts of important cell cycle components are stabilized, recruited at the appropriate time for translation, and eliminated to modulate oocyte meiotic progression remains unclear. A better understanding of these mechanisms will provide invaluable insights for the preconditions of developmental competence acquisition, with important implications for the treatment of infertility. This review discusses how the storage, localization, translation, and processing of oocyte mRNAs are regulated, and how these contribute to oocyte maturation progression.
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Affiliation(s)
- Yanwen Jiang
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Deepak Adhikari
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, 19 Innovation Walk, Melbourne, VIC, 3800, Australia
| | - Chunjin Li
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Xu Zhou
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
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Salinas-Saavedra M, Martindale MQ. Par protein localization during the early development of Mnemiopsis leidyi suggests different modes of epithelial organization in the metazoa. eLife 2020; 9:54927. [PMID: 32716297 PMCID: PMC7441587 DOI: 10.7554/elife.54927] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/23/2020] [Indexed: 02/07/2023] Open
Abstract
In bilaterians and cnidarians, epithelial cell-polarity is regulated by the interactions between Par proteins, Wnt/PCP signaling pathway, and cell-cell adhesion. Par proteins are highly conserved across Metazoa, including ctenophores. But strikingly, ctenophore genomes lack components of the Wnt/PCP pathway and cell-cell adhesion complexes raising the question if ctenophore cells are polarized by mechanisms involving Par proteins. Here, by using immunohistochemistry and live-cell imaging of specific mRNAs, we describe for the first time the subcellular localization of selected Par proteins in blastomeres and epithelial cells during the embryogenesis of the ctenophore Mnemiopsis leidyi. We show that these proteins distribute differently compared to what has been described for other animals, even though they segregate in a host-specific fashion when expressed in cnidarian embryos. This differential localization might be related to the emergence of different junctional complexes during metazoan evolution.
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Affiliation(s)
- Miguel Salinas-Saavedra
- The Whitney Laboratory for Marine Bioscience, and the Department of Biology, University of Florida, St. Augustine, United States
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, and the Department of Biology, University of Florida, St. Augustine, United States
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Wang JC, Lv H, Wu KL, Zhang YS, Luo HN, Chen ZJ. Discs large homologue 1 (Dlg1) coordinates mouse oocyte polarisation during maturation. Reprod Fertil Dev 2018; 29:1699-1707. [PMID: 27651179 DOI: 10.1071/rd15486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 08/19/2016] [Indexed: 11/23/2022] Open
Abstract
Mouse oocyte meiotic division requires the establishment of asymmetries in the oocyte before division, indicating the presence of polarity-establishing molecules. During mouse oocyte maturation proper orientation and positioning of the meiotic spindle at the oocyte cortex, as well as polarity in the oocyte cytoplasm and its oolemma, are necessary for the formation of functional haploid oocytes. Discs large homologue 1 (Dlg1) protein is a conserved protein that regulates cell polarity. In the present study, we found that Dlg1 was expressed at different stages of oocyte development. The localisation of Dlg1 during mouse oocyte maturation and its relationship with the cytoskeleton were analysed. Our data show that at the germinal vesicle stage, Dlg1 was present in the cytoplasm, prominently surrounding the germinal vesicle membrane. During maturation, Dlg1 became highly polarised by associating with the spindle and formed characteristic crescent-shaped accumulations under the cortex. Addition of nocodazole or cytochalasin B into the culture medium at different stages changed the localisation of Dlg1, indicating that the organisation of Dlg1 is a complex multi-step process and is dependent on microtubules and microfilaments. More importantly, we found that silencing of Dlg1 compromised the G2-M transition.
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Affiliation(s)
- Jun-Chao Wang
- Centre of Reproductive Medicine, Tianjin Central Hospital of Obstetrics and Gynaecology, 156 Nankai Sanma Road, Tianjin 300100, China
| | - Hong Lv
- Centre for Reproductive Medicine, Provincial Hospital Affiliated to Shandong University, Jinan 250001
| | - Ke-Liang Wu
- Centre for Reproductive Medicine, Provincial Hospital Affiliated to Shandong University, Jinan 250001
| | - Yun-Shan Zhang
- Centre of Reproductive Medicine, Tianjin Central Hospital of Obstetrics and Gynaecology, 156 Nankai Sanma Road, Tianjin 300100, China
| | - Hai-Ning Luo
- Centre of Reproductive Medicine, Tianjin Central Hospital of Obstetrics and Gynaecology, 156 Nankai Sanma Road, Tianjin 300100, China
| | - Zi-Jiang Chen
- Centre for Reproductive Medicine, Provincial Hospital Affiliated to Shandong University, Jinan 250001
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Abstract
During the very first days of mammalian development, the embryo forms a structure called the blastocyst. The blastocyst consists of two cell types: the trophectoderm (TE), which implants the embryo in the uterus and the inner cell mass (ICM), which gives rise to all cells of the mammalian body. Previous works identified how cells differentiate according to their position within the embryo: TE for surface cells and ICM for internal cells. It is therefore essential to understand how cells acquire their position in the first place. During the formation of the blastocyst, cells distort and relocate as a consequence of forces that are generated by the cells themselves. Recently, several important studies have identified the forces and cellular mechanisms leading to the shaping of the ICM. Here, I describe how these studies led us to understand how contractile forces shape the mammalian embryo to position and differentiate the ICM.
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Affiliation(s)
- Jean-Léon Maître
- Institut Curie, PSL Research University, CNRS UMR3215 Inserm U934, 26 rue d'Ulm, 75248 Paris, France - Équipe mécanique du développement mammifère, Unité Génétique et Biologie du Développement, Institut Curie, 26 rue d'Ulm, 75248 Paris cedex 05, France
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7
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Forceful patterning in mouse preimplantation embryos. Semin Cell Dev Biol 2017; 71:129-136. [PMID: 28577924 DOI: 10.1016/j.semcdb.2017.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/16/2017] [Accepted: 05/21/2017] [Indexed: 12/22/2022]
Abstract
The generation of a functional organism from a single, fertilized ovum requires the spatially coordinated regulation of diverse cell identities. The establishment and precise arrangement of differentiated cells in developing embryos has, historically, been extensively studied by geneticists and developmental biologists. While chemical gradients and genetic regulatory networks are widely acknowledged to play significant roles in embryo patterning, recent studies have highlighted that mechanical forces generated by, and exerted on, embryos are also crucial for the proper control of cell differentiation and morphogenesis. Here we review the most recent findings in murine preimplantation embryogenesis on the roles of cortical tension in the coupling of cell-fate determination and cell positioning in 8-16-cell-stage embryos. These basic principles of mechanochemical coupling in mouse embryos can be applied to other pattern formation phenomena that rely on localized modifications of cell polarity proteins and actin cytoskeletal components and activities.
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Tuccilli C, Baldini E, Arlot-Bonnemains Y, Chesnel F, Sorrenti S, De Vito C, D'Armiento E, Antonelli A, Fallahi P, Watutantrige S, Tartaglia F, Barollo S, Mian C, Arcieri S, Mascagni D, Pironi D, Bononi M, Vergine M, Monti M, Filippini A, Ulisse S. Expression and prognostic value of the cell polarity PAR complex members in thyroid cancer. Int J Oncol 2017; 50:1413-1422. [PMID: 28350047 DOI: 10.3892/ijo.2017.3907] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 01/11/2017] [Indexed: 11/05/2022] Open
Abstract
Establishment and maintenance of the apical-basal cell polarity, required for proper replication, migration, specialized functions and tissue morphogenesis, relies on three evolutionary conserved complexes: PAR, CRUMBS and SCRIBBLE. Loss of cell polarity/cohesiveness (LOP/C) is implicated in cancer progression, and members of the polarity complex have been described as either oncogenes or oncosuppressors. However, no information on their role in thyroid cancer (TC) progression is available. In the present study, we evaluated the gene expression of the PAR complex members aPKCι, PARD3α/β and PARD6α/β/γ in 95 papillary TC (PTC), compared to their normal matched tissues and in 12 anaplastic TC (ATC). The mRNA and protein levels of investigated genes were altered in the majority of PTC and ATC tissues. In PTC, univariate analysis showed that reduced expression of aPKCι, PARD3β and PARD6γ mRNAs is associated with increased tumor size, and the reduced expression of PARD3β mRNA is associated also with recurrences. Multivariate analysis demonstrated that the presence of lymph node metastasis at diagnosis and the reduced expression of PARD3β are independent risk factors for recurrences, with hazard ratio, respectively, of 8.21 (p=0.006) and 3.04 (p=0.029). The latter result was confirmed by the Kaplan-Meier analysis, which evidenced the association between decreased PARD3β mRNA levels and shorter disease-free interval. In conclusion, we demonstrated that the expression of PAR complex components is deregulated in the majority of PTC and there is a general trend towards their reduction in ATC tissues. Moreover, a prognostic value for the PARD3β gene in PTCs is suggested.
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Affiliation(s)
- Chiara Tuccilli
- Department of Experimental Medicine, 'Sapienza' University of Rome, Rome, Italy
| | - Enke Baldini
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | | | - Frank Chesnel
- CNRS-UMR 6290 (IGDR) Université Rennes 1, Rennes, France
| | - Salvatore Sorrenti
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Corrado De Vito
- Department of Public Health and Infectious Diseases, 'Sapienza' University of Rome, Rome, Italy
| | - Eleonora D'Armiento
- Department of Experimental Medicine, 'Sapienza' University of Rome, Rome, Italy
| | - Alessandro Antonelli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Poupak Fallahi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | | | | | - Susi Barollo
- Department of Medicine, University of Padua, Padua, Italy
| | - Caterina Mian
- Department of Medicine, University of Padua, Padua, Italy
| | - Stefano Arcieri
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Domenico Mascagni
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Daniele Pironi
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Marco Bononi
- Department of Surgery 'Pietro Valdoni', 'Sapienza' University of Rome, Rome, Italy
| | - Massimo Vergine
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Massimo Monti
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Angelo Filippini
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
| | - Salvatore Ulisse
- Department of Surgical Sciences, 'Sapienza' University of Rome, Rome, Italy
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Abstract
Fully grown oocytes arrest meiosis at prophase I and deposit maternal RNAs. A subset of maternal transcripts is stored in a dormant state in the oocyte, and the timely driven translation of specific mRNAs guides meiotic progression, the oocyte-embryo transition, and early embryo development. In the absence of transcription, the regulation of gene expression in oocytes is controlled almost exclusively at the level of transcriptome and proteome stabilization and at the level of protein synthesis.This chapter focuses on the recent findings on RNA distribution related to the temporal and spatial translational control of the meiotic cycle progression in mammalian oocytes. We discuss the most relevant mechanisms involved in the organization of the oocyte's maternal transcriptome storage and localization, and the regulation of translation, in correlation with the regulation of oocyte meiotic progression.
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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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11
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Hosseini SM, Moulavi F, Tanhaie-Vash N, Asgari V, Ghanaei HR, Abedi-Dorche M, Jafarzadeh N, Gourabi H, Shahverdi AH, Dizaj AV, Shirazi A, Nasr-Esfahani MH. The Principal Forces of Oocyte Polarity Are Evolutionary Conserved but May Not Affect the Contribution of the First Two Blastomeres to the Blastocyst Development in Mammals. PLoS One 2016; 11:e0148382. [PMID: 27030988 PMCID: PMC4816511 DOI: 10.1371/journal.pone.0148382] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/18/2016] [Indexed: 11/26/2022] Open
Abstract
Oocyte polarity and embryonic patterning are well-established features of development in lower species. Whether a similar form of pre-patterning exists in mammals is currently under hot debate in mice. This study investigated this issue for the first time in ovine as a large mammal model. Microsurgical trisection of unfertilized MII-oocytes revealed that cortical cytoplasm around spindle (S) contained significant amounts of total maternal mRNAs and proteins compared to matched cytoplast hemispheres that were located either near (NS) or far (FS) -to-spindle. RT-qPCR provided striking examples of maternal mRNA localized to subcellular substructures S (NPM2, GMNN, H19, PCAF, DNMT3A, DNMT1, and STELLA), NS (SOX2, NANOG, POU5F1, and TET1), and FS (GCN) of MII oocyte. Immunoblotting revealed that specific maternal proteins DNMT3A and NANOG were asymmetrically enriched in MII-spindle-half of the oocytes. Topological analysis of sperm entry point (SEP) revealed that sperm preferentially entered via the MII-spindle-half of the oocytes. Even though, the topological position of first cleavage plane with regard to SEP was quite stochastic. Spatial comparison of lipid content revealed symmetrical distribution of lipids between 2-cell blastomeres. Lineage tracing using Dil, a fluorescent dye, revealed that while the progeny of leading blastomere of 2-cell embryos contributed to more cells in the developed blastocysts compared to lagging counterpart, the contributions of leading and lagging blastomeres to the embryonic-abembryonic parts of the developed blastocysts were almost unbiased. And finally, separated sister blastomeres of 2-cell embryos had an overall similar probability to arrest at any stage before the blastocyst (2-cell, 4-cell, 8-cell, and morula) or to achieve the blastocyst stage. It was concluded that the localization of maternal mRNAs and proteins at the spindle are evolutionarily conserved between mammals unfertilized ovine oocyte could be considered polar with respect to the spatial regionalization of maternal transcripts and proteins. Even though, the principal forces of this definitive oocyte polarity may not persist during embryonic cleavages.
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Affiliation(s)
- Sayyed-Morteza Hosseini
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Fariba Moulavi
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Nima Tanhaie-Vash
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Vajihe Asgari
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Hamid-Reza Ghanaei
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Maryam Abedi-Dorche
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Naser Jafarzadeh
- Department of Medical Physics, Tarbiat Modares University, Tehran, Iran
| | - Hossein Gourabi
- Department of Genetics at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, P.O. Box: 19395–4644, Tehran, Iran
| | - Abdol-Hossein Shahverdi
- Department of Embryology at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Medicine, ACECR, Tehran, Iran
| | - Ahmad Vosough Dizaj
- Department of Reproductive Imaging at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Abolfazl Shirazi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
- Research Institute of Animal Embryo Technology, Shahrekord University, Shahrekord, Iran
- * E-mail: (AS); (MHNE)
| | - Mohammad-Hossein Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
- * E-mail: (AS); (MHNE)
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12
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Ajduk A, Zernicka-Goetz M. Polarity and cell division orientation in the cleavage embryo: from worm to human. Mol Hum Reprod 2015; 22:691-703. [PMID: 26660321 PMCID: PMC5062000 DOI: 10.1093/molehr/gav068] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/25/2015] [Indexed: 01/01/2023] Open
Abstract
Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism. Due to a series of mitotic divisions, the large volume of a fertilized egg is divided into numerous smaller, nucleated cells—blastomeres. Embryos of different phyla divide according to different patterns, but molecular mechanism of these early divisions remains surprisingly conserved. In the present paper, we describe how polarity cues, cytoskeleton and cell-to-cell communication interact with each other to regulate orientation of the early embryonic division planes in model animals such as Caenorhabditis elegans, Drosophila and mouse. We focus particularly on the Par pathway and the actin-driven cytoplasmic flows that accompany it. We also describe a unique interplay between Par proteins and the Hippo pathway in cleavage mammalian embryos. Moreover, we discuss the potential meaning of polarity, cytoplasmic dynamics and cell-to-cell communication as quality biomarkers of human embryos.
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Affiliation(s)
- Anna Ajduk
- Department of Embryology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Magdalena Zernicka-Goetz
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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13
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Translation in the mammalian oocyte in space and time. Cell Tissue Res 2015; 363:69-84. [PMID: 26340983 DOI: 10.1007/s00441-015-2269-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/03/2015] [Indexed: 02/07/2023]
Abstract
A hallmark of oocyte development in mammals is the dependence on the translation and utilization of stored RNA and proteins rather than the de novo transcription of genes in order to sustain meiotic progression and early embryo development. In the absence of transcription, the completion of meiosis and early embryo development in mammals relies significantly on maternally synthesized RNAs. Post-transcriptional control of gene expression at the translational level has emerged as an important cellular function in normal development. Therefore, the regulation of gene expression in oocytes is controlled almost exclusively at the level of mRNA and protein stabilization and protein synthesis. This current review is focused on the recently emerged findings on RNA distribution related to the temporal and spatial translational control of the meiotic progression of the mammalian oocyte.
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Salinas-Saavedra M, Stephenson TQ, Dunn CW, Martindale MQ. Par system components are asymmetrically localized in ectodermal epithelia, but not during early development in the sea anemone Nematostella vectensis. EvoDevo 2015; 6:20. [PMID: 26101582 PMCID: PMC4476184 DOI: 10.1186/s13227-015-0014-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/12/2015] [Indexed: 11/10/2022] Open
Abstract
Background The evolutionary origins of cell polarity in metazoan embryos are unclear. In most bilaterian animals, embryonic and cell polarity are set up during embryogenesis with the same molecules being utilized to regulate tissue polarity at different life stages. Atypical protein kinase C (aPKC), lethal giant larvae (Lgl), and Partitioning-defective (Par) proteins are conserved components of cellular polarization, and their role in establishing embryonic asymmetry and tissue polarity have been widely studied in model bilaterian groups. However, the deployment and role of these proteins in animals outside Bilateria has not been studied. We address this by characterizing the localization of different components of the Par system during early development of the sea anemone Nematostella vectensis, a member of the clade Cnidaria, the sister group to bilaterian animals. Results Immunostaining using specific N. vectensis antibodies and the overexpression of mRNA-reporter constructs show that components of the N. vectensis Par system (NvPar-1, NvPar-3, NvPar-6, NvaPKC, and NvLgl) distribute throughout the microtubule cytoskeleton of eggs and early embryos without clear polarization along any embryonic axis. However, they become asymmetrically distributed at later stages, when the embryo forms an ectodermal epithelial layer. NvLgl and NvPar-1 localize in the basolateral cortex, and NvaPKC, NvPar-6, and NvPar-3 at the apical zone of the cell in a manner seen in bilaterian animals. Conclusions The cnidarian N. vectensis exhibits clear polarity at all stages of early embryonic development, which appears to be established independent of the Par system reported in many bilaterian embryos. However, in N. vectensis, using multiple immunohistochemical and fluorescently labeled markers in vivo, components of this system are deployed to organize epithelial cell polarity at later stages of development. This suggests that Par system proteins were co-opted to organize early embryonic cell polarity at the base of the Bilateria and that, therefore, different molecular mechanisms operate in early cnidarian embryogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0014-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Miguel Salinas-Saavedra
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
| | - Thomas Q Stephenson
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
| | - Casey W Dunn
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
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15
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Sharif B, Fadero T, Maddox AS. Anillin localization suggests distinct mechanisms of division plane specification in mouse oogenic meiosis I and II. Gene Expr Patterns 2015; 17:98-106. [PMID: 25818309 DOI: 10.1016/j.gep.2015.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 03/05/2015] [Accepted: 03/13/2015] [Indexed: 01/22/2023]
Abstract
Anillin is a conserved cytokinetic ring protein implicated in actomyosin cytoskeletal organization and cytoskeletal-membrane linkage. Here we explored anillin localization in the highly asymmetric divisions of the mouse oocyte that lead to the extrusion of two polar bodies. The purposes of polar body extrusion are to reduce the chromosome complement within the egg to haploid, and to retain the majority of the egg cytoplasm for embryonic development. Anillin's proposed roles in cytokinetic ring organization suggest that it plays important roles in achieving this asymmetric division. We report that during meiotic maturation, anillin mRNA is expressed and protein levels steadily rise. In meiosis I, anillin localizes to a cortical cap overlying metaphase I spindles, and a broad ring over anaphase spindles that are perpendicular to the cortex. Anillin is excluded from the cortex of the prospective first polar body, and highly enriched in the cytokinetic ring that severs the polar body from the oocyte. In meiosis II, anillin is enriched in a cortical stripe precisely coincident with and overlying the meiotic spindle midzone. These results suggest a model in which this cortical structure contributes to spindle re-alignment in meiosis II. Thus, localization of anillin as a conserved cytokinetic ring marker illustrates that the geometry of the cytokinetic ring is distinct between the two oogenic meiotic cytokineses in mammals.
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Affiliation(s)
- Bedra Sharif
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada
| | - Tanner Fadero
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
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Wang ZB, Jiang ZZ, Zhang QH, Hu MW, Huang L, Ou XH, Guo L, Ouyang YC, Hou Y, Brakebusch C, Schatten H, Sun QY. Specific deletion of Cdc42 does not affect meiotic spindle organization/migration and homologous chromosome segregation but disrupts polarity establishment and cytokinesis in mouse oocytes. Mol Biol Cell 2013; 24:3832-41. [PMID: 24131996 PMCID: PMC3861080 DOI: 10.1091/mbc.e13-03-0123] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oocyte-specific deletion of Cdc42 has little effect on meiotic spindle organization and migration to the cortex but inhibits polar body emission, although homologous chromosome segregation occurs. The failure of cytokinesis is due to loss of polarized Arp2/3 accumulation and actin cap formation, and thus the defective contract ring. Mammalian oocyte maturation is distinguished by highly asymmetric meiotic divisions during which a haploid female gamete is produced and almost all the cytoplasm is maintained in the egg for embryo development. Actin-dependent meiosis I spindle positioning to the cortex induces the formation of a polarized actin cap and oocyte polarity, and it determines asymmetric divisions resulting in two polar bodies. Here we investigate the functions of Cdc42 in oocyte meiotic maturation by oocyte-specific deletion of Cdc42 through Cre-loxP conditional knockout technology. We find that Cdc42 deletion causes female infertility in mice. Cdc42 deletion has little effect on meiotic spindle organization and migration to the cortex but inhibits polar body emission, although homologous chromosome segregation occurs. The failure of cytokinesis is due to the loss of polarized Arp2/3 accumulation and actin cap formation; thus the defective contract ring. In addition, we correlate active Cdc42 dynamics with its function during polar body emission and find a relationship between Cdc42 and polarity, as well as polar body emission, in mouse oocytes.
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Affiliation(s)
- Zhen-Bo Wang
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China Molecular Pathology Section, Department of Biomedical Sciences, Biotech Research and Innovation Centre, University of Copenhagen, 2200 Copenhagen, Denmark Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211
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Sun SC, Kim NH. Molecular mechanisms of asymmetric division in oocytes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:883-897. [PMID: 23764118 DOI: 10.1017/s1431927613001566] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In contrast to symmetric division in mitosis, mammalian oocyte maturation is characterized by asymmetric cell division that produces a large egg and a small polar body. The asymmetry results from oocyte polarization, which includes spindle positioning, migration, and cortical reorganization, and this process is critical for fertilization and the retention of maternal components for early embryo development. Although actin dynamics are involved in this process, the molecular mechanism underlying this remained unclear until the use of confocal microscopy and live cell imaging became widespread in recent years. Information obtained through a PubMed database search of all articles published in English between 2000 and 2012 that included the phrases "oocyte, actin, spindle migration," "oocyte, actin, polar body," or "oocyte, actin, asymmetric division" was reviewed. The actin nucleation factor actin-related protein 2/3 complex and its nucleation-promoting factors, formins and Spire, and regulators such as small GTPases, partitioning-defective/protein kinase C, Fyn, microRNAs, cis-Golgi apparatus components, myosin/myosin light-chain kinase, spindle stability regulators, and spindle assembly checkpoint regulators, play critical roles in asymmetric cell division in oocytes. This review summarizes recent findings on these actin-related regulators in mammalian oocyte asymmetric division and outlines a complete signaling pathway.
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Affiliation(s)
- Shao-Chen Sun
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
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18
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Bruce AW. Generating different genetic expression patterns in the early embryo: insights from the mouse model. Reprod Biomed Online 2013; 27:586-92. [PMID: 23768616 DOI: 10.1016/j.rbmo.2013.03.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/02/2013] [Accepted: 03/19/2013] [Indexed: 11/26/2022]
Abstract
The divergence of two differentiating extraembryonic cell types (trophectoderm and primitive endoderm) from the pluripotent epiblast population (the source of fetal progenitor cells) by the blastocyst stage of mouse development relies upon the activation and execution of lineage-specific gene expression programmes. While our understanding of the central transcription factor 'effectors' directing these cell-fate choices has accumulated rapidly, what is less clear is how the differential expression of such genes within the diverging lineages is initially generated. This review summarizes and consolidates current understanding. I introduce the traditional concept and importance of a cell's spatial location within the embryo, referencing recent mechanistic and molecular insights relating to cell fate. Additionally, I address the growing body of evidence that suggests that heterogeneities among blastomeres precede, and possibly inform, their spatial segregation in the embryo. I also discuss whether the origins of such early heterogeneity are stochastic and/or indicative of intrinsic properties of the embryo. Lastly, I argue that the robustness and regulative capacity of preimplantation embryonic development may reflect the existence of multiple converging, if not wholly redundant, mechanisms that act together to generate the necessary diversity of inter-cell-lineage gene expression patterns.
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Affiliation(s)
- Alexander W Bruce
- Laboratory of Developmental Biology and Genetics, Department of Molecular Biology, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice (Budweis), Czech Republic; Institute of Entomology, Biology Centre of the Czech Academy of Sciences in České Budějovice, Branišovská 31, 37005 České Budějovice (Budweis), Czech Republic.
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Dehapiot B, Carrière V, Carroll J, Halet G. Polarized Cdc42 activation promotes polar body protrusion and asymmetric division in mouse oocytes. Dev Biol 2013; 377:202-12. [PMID: 23384564 PMCID: PMC3690527 DOI: 10.1016/j.ydbio.2013.01.029] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 12/22/2012] [Accepted: 01/25/2013] [Indexed: 11/28/2022]
Abstract
Asymmetric meiotic divisions in mammalian oocytes rely on the eccentric positioning of the spindle and the remodeling of the overlying cortex, resulting in the formation of small polar bodies. The mechanism of this cortical polarization, exemplified by the formation of a thick F-actin cap, is poorly understood. Cdc42 is a major player in cell polarization in many systems; however, the spatio-temporal dynamics of Cdc42 activation during oocyte meiosis, and its contribution to mammalian oocyte polarization, have remained elusive. In this study, we investigated Cdc42 activation (Cdc42–GTP), dynamics and role during mouse oocyte meiotic divisions. We show that Cdc42–GTP accumulates in restricted cortical regions overlying meiotic chromosomes or chromatids, in a Ran–GTP-dependent manner. This polarized activation of Cdc42 is required for the recruitment of N-WASP and the formation of F-actin-rich protrusions during polar body formation. Cdc42 inhibition in MII oocytes resulted in the release of N-WASP into the cytosol, a loss of the polarized F-actin cap, and a failure to protrude the second polar body. Cdc42 inhibition also resulted in central spindle defects in activated MII oocytes. In contrast, emission of the first polar body during oocyte maturation could occur in the absence of a functional Cdc42/N-WASP pathway. Therefore, Cdc42 is a new protagonist in chromatin-induced cortical polarization in mammalian oocytes, with an essential role in meiosis II completion, through the recruitment and activation of N-WASP, downstream of the chromatin-centered Ran–GTP gradient.
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Affiliation(s)
- Benoit Dehapiot
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, F-35043 Rennes, France
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20
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Regulation of cell polarity and RNA localization in vertebrate oocytes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 306:127-85. [PMID: 24016525 DOI: 10.1016/b978-0-12-407694-5.00004-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It has long been appreciated that the inheritance of maternal cytoplasmic determinants from different regions of the egg can lead to differential specification of blastomeres during cleavage. Localized RNAs are important determinants of cell fate in eggs and embryos but are also recognized as fundamental regulators of cell structure and function. This chapter summarizes recent molecular and genetic experiments regarding: (1) mechanisms that regulate polarity during different stages of vertebrate oogenesis, (2) pathways that localize presumptive protein and RNA determinants within the polarized oocyte and egg, and (3) how these determinants act in the embryo to determine the ultimate cell fates. Emphasis is placed on studies done in Xenopus, where extensive work has been done in these areas, and comparisons are drawn with fish and mammals. The prospects for future work using in vivo genome manipulation and other postgenomic approaches are also discussed.
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21
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Maddox AS, Azoury J, Dumont J. Polar body cytokinesis. Cytoskeleton (Hoboken) 2012; 69:855-68. [PMID: 22927361 DOI: 10.1002/cm.21064] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 08/20/2012] [Indexed: 02/04/2023]
Abstract
Polar body cytokinesis is the physical separation of a small polar body from a larger oocyte or ovum. This maternal meiotic division shares many similarities with mitotic and spermatogenic cytokinesis, but there are several distinctions, which will be discussed in this review. We synthesize results from many different model species, including those popular for their genetics and several that are more obscure in modern cell biology. The site of polar body division is determined before anaphase, by the eccentric, cortically associated meiotic spindle. Depending on the species, either the actin or microtubule cytoskeleton is required for spindle anchoring. Chromatin is necessary and sufficient to elicit differentiation of the associated cortex, via Ran-based signaling. The midzone of the anaphase spindle serves as a hub for regulatory complexes that elicit Rho activation, and ultimately actomyosin contractile ring assembly and contraction. Polar body cytokinesis uniquely requires another Rho family GTPase, Cdc42, for dynamic reorganization of the polar cortex. This is perhaps due to the considerable asymmetry of this division, wherein the polar body and the oocyte/ovum have distinct fates and very different sizes. Thus, maternal meiotic cytokinesis appears to occur via simultaneous polar relaxation and equatorial contraction, since the polar body is extruded from the spherical oocyte through the nascent contractile ring. As such, polar body cytokinesis is an interesting and important variation on the theme of cell division.
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Affiliation(s)
- Amy Shaub Maddox
- Institut de recherche en immunology et en cancerologie (IRIC), Université de Montréal, Montréal, Quebec, Canada.
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22
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Martínez-Frías ML. Assessing pre-implantation embryo development in mice provides a rationale for understanding potential adverse effects of ART and PGD procedures. Am J Med Genet A 2012; 158A:2526-33. [PMID: 22903927 DOI: 10.1002/ajmg.a.35573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 07/02/2012] [Indexed: 11/07/2022]
Abstract
Although the molecular events controlling human pre-implantation development remain unclear, mechanisms have been identified by analyzing these stages in mice. Through this approach, considerable insight has been gained into the events that operate to determine the first two cell fate decisions, occurring from zygote formation to the blastocyst prior to implantation. These mechanisms are related to cell polarization, cell division, cell-cell contact, and cell spatial position. Two developmental stages are essential for these processes to proceed adequately. Firstly, the second polar body must anchor to the external membrane during the first mitotic divisions of the embryo as its position is strongly biased to determine the plane of polarity. This in turn has important influence on the fate of the early blastomeres. Secondly, in the transition from the 8- to 16-cell stage, the cells that will form the inner cell mass are determined. Moreover, analyses performed on human oocytes and embryos have identified similar processes to those reported in mice and thus are evolutionarily conserved. Therefore, the understanding of mice pre-implantation embryo development provides a rationale to interpret current results of potential long-term adverse outcomes of Assisted Reproductive Technologies and Pre-implantation Genetic Diagnosis (PGD).
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23
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Actin cytoskeleton in cell polarity and asymmetric division during mouse oocyte maturation. Cytoskeleton (Hoboken) 2012; 69:727-37. [DOI: 10.1002/cm.21048] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/18/2012] [Accepted: 06/21/2012] [Indexed: 12/22/2022]
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24
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Liu XJ. Polar body emission. Cytoskeleton (Hoboken) 2012; 69:670-85. [PMID: 22730245 DOI: 10.1002/cm.21041] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/15/2012] [Accepted: 05/21/2012] [Indexed: 12/13/2022]
Abstract
Generation of a haploid female germ cell, the egg, consists of two rounds of asymmetric cell division (meiosis I and meiosis II), yielding two diminutive and nonviable polar bodies and a large haploid egg. Animal eggs are also unique in the lack of centrioles and therefore form meiotic spindles without the pre-existence of the two dominant microtubule organizing centers (centrosomes) found in mitosis. Meiotic spindle assembly is further complicated by the unique requirement of sister chromatid mono-oriented in meiosis I. Nonetheless, the eggs appear to adopt many of the same proteins and mechanisms described in mitosis, with necessary modifications to accommodate their special needs. Unraveling these special modifications will not only help understanding animal reproduction, but should also enhance our understanding of cell division in general.
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Affiliation(s)
- X Johné Liu
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa Hospital Civic Campus, 1053 Carling Avenue, Ottawa, K1Y 4E9, Canada.
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25
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Spindle positioning in mammalian oocytes. Exp Cell Res 2012; 318:1442-7. [PMID: 22406266 DOI: 10.1016/j.yexcr.2012.02.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/21/2012] [Accepted: 02/22/2012] [Indexed: 11/22/2022]
Abstract
To preserve the maternal stores accumulated during oogenesis for further embryo development, oocytes divide asymmetrically which minimizes the volume of cytoplasm lost with each set of haploid genome. To ensure asymmetric division to occur, oocytes have to position their division spindle asymmetrically as well as tailor the size of daughter cells to the chromatin mass. In this review, we will discuss the recent advances in the field, with emphasis on the control mechanisms involved in meiotic spindle positioning in mammalian oocytes.
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Kloc M, Ghobrial RM, Borsuk E, Kubiak JZ. Polarity and asymmetry during mouse oogenesis and oocyte maturation. Results Probl Cell Differ 2012; 55:23-44. [PMID: 22918799 DOI: 10.1007/978-3-642-30406-4_2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell polarity and asymmetry play a fundamental role in embryo development. The unequal segregation of determinants, cues, and activities is the major event in the differentiation of cell fate and function in all multicellular organisms. In oocytes, polarity and asymmetry in the distribution of different molecules are prerequisites for the progression and proper outcome of embryonic development. The mouse oocyte, like the oocytes of other mammals, seems to apply a less stringent strategy of polarization than other vertebrates. The mouse embryo undergoes a regulative type of development, which permits the full rectification of development even if the embryo loses up to half of its cells or its size is experimentally doubled during the early stages of embryogenesis. Such pliability is strongly related to the proper oocyte polarization before fertilization. Thus, the molecular mechanisms leading to the development and maintenance of oocyte polarity must be included in any fundamental understanding of the principles of embryo development. In this chapter, we provide an overview of current knowledge regarding the development and maintenance of polarity and asymmetry in the distribution of organelles and molecules in the mouse oocyte. Curiously, the mouse oocyte becomes polarized at least twice during ontogenesis; the question of how this phenomenon is achieved and what role it might play is addressed in this chapter.
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Affiliation(s)
- Malgorzata Kloc
- The Methodist Hospital, Department of Surgery, Houston, TX, USA.
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27
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Prulière G, Cosson J, Chevalier S, Sardet C, Chenevert J. Atypical protein kinase C controls sea urchin ciliogenesis. Mol Biol Cell 2011; 22:2042-53. [PMID: 21508313 PMCID: PMC3113769 DOI: 10.1091/mbc.e10-10-0844] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The distribution and function of aPKC are examined during sea urchin ciliogenesis. The kinase concentrates in a ring at the transition zone between the basal body and the elongating axoneme. Inhibition of aPKC results in mislocalization of the kinase and defective ciliogenesis. Thus aPKC controls the growth of motile cilia in invertebrate embryos. The atypical protein kinase C (aPKC) is part of the conserved aPKC/PAR6/PAR3 protein complex, which regulates many cell polarity events, including the formation of a primary cilium at the apical surface of epithelial cells. Cilia are highly organized, conserved, microtubule-based structures involved in motility, sensory processes, signaling, and cell polarity. We examined the distribution and function of aPKC in the sea urchin embryo, which forms a swimming blastula covered with motile cilia. We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages. During the blastula and gastrula stages the kinase localizes at the base of cilia, forming a ring at the transition zone between the basal body and the elongating axoneme. A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming. Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos. We suggest that aPKC might function to phosphorylate kinesin and so activate the transport of intraflagellar vesicles.
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Affiliation(s)
- Gérard Prulière
- Observatoire Océanologique, Biologie du Développement, Université Pierre et Marie Curie and CNRS, Villefranche-sur-Mer, France.
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VerMilyea MD, Maneck M, Yoshida N, Blochberger I, Suzuki E, Suzuki T, Spang R, Klein CA, Perry ACF. Transcriptome asymmetry within mouse zygotes but not between early embryonic sister blastomeres. EMBO J 2011; 30:1841-51. [PMID: 21468028 DOI: 10.1038/emboj.2011.92] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 03/03/2011] [Indexed: 11/09/2022] Open
Abstract
Transcriptome regionalization is an essential polarity determinant among metazoans, directing embryonic axis formation during normal development. Although conservation of this principle in mammals is assumed, recent evidence is conflicting and it is not known whether transcriptome asymmetries exist within unfertilized mammalian eggs or between the respective cleavage products of early embryonic divisions. We here address this by comparing transcriptome profiles of paired single cells and sub-cellular structures obtained microsurgically from mouse oocytes and totipotent embryos. Paired microsurgical spindle and remnant samples from unfertilized metaphase II oocytes possessed distinguishable profiles. Fertilization produces a totipotent 1-cell embryo (zygote) and associated spindle-enriched second polar body whose paired profiles also differed, reflecting spindle transcript enrichment. However, there was no programmed transcriptome asymmetry between sister cells within 2- or 3-cell embryos. Accordingly, there is transcriptome asymmetry within mouse oocytes, but not between the sister blastomeres of early embryos. This work places constraints on pre-patterning in mammals and provides documentation correlating potency changes and transcriptome partitioning at the single-cell level.
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Affiliation(s)
- Matthew D VerMilyea
- Laboratory of Mammalian Molecular Embryology, RIKEN Center for Developmental Biology, Kobe, Japan
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29
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The polarity protein Par6 is coupled to the microtubule network during molluscan early embryogenesis. Biochem Biophys Res Commun 2011; 404:173-8. [DOI: 10.1016/j.bbrc.2010.11.087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 11/18/2010] [Indexed: 11/19/2022]
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Brunet S, Verlhac MH. Positioning to get out of meiosis: the asymmetry of division. Hum Reprod Update 2010; 17:68-75. [DOI: 10.1093/humupd/dmq044] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Lv H, Wang JC, Wu KL, Gao X, Wang LC, You L, Chen ZJ. Numb regulates meiotic spindle organisation in mouse oocytes. Reprod Fertil Dev 2010; 22:664-72. [PMID: 20353726 DOI: 10.1071/rd09236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 10/12/2009] [Indexed: 11/23/2022] Open
Abstract
Numb is an adaptor protein that controls the fate of cells in different species through asymmetrical inheritance by sibling cells during division. It has been investigated extensively in mitosis, mostly in neural progenitor cells, but its function in meiosis remains unknown. The present study was designed to investigate the expression, subcellular localisation and functional roles of Numb during mouse oocyte meiotic maturation. Using real-time polymerase chain reaction and western blotting, we found that the expression of Numb increased from the germinal vesicle (GV) to MII stages. Immunofluorescent staining revealed that Numb was mainly concentrated in the GV before meiosis resumption, aggregated in the vicinity of the chromosomes after GV breakdown and then localised to the spindle poles from prometaphase I to MII. Nocodazole treatment resulted in spindle destruction and Numb diffusion into the cytoplasm. However, Numb appeared at the spindle poles again once the spindles had formed when nocodazole-treated oocytes were washed and cultured for spindle recovery. Depletion of Numb by RNA interference resulted in chromosome misalignment, spindle deformation and even doubled spindle formation. Our results suggest that Numb is critical for spindle organisation during mouse oocytes meiosis. The present study provides evidence of a new function for Numb in addition to its action as a cell fate-determining factor.
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Affiliation(s)
- H Lv
- Center for Reproductive Medicine, Provincial Hospital Affiliated to Shandong University, Key Laboratory of Reproductive Medicine, Shandong Province, Jinan 250021, China
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Abstract
This review describes the three classical models (mosaic, positional, and polarization) proposed to explain blastocyst formation and summarizes the evidence concerning them. It concludes that the polarization model incorporates elements of the other two models and best explains most known information. I discuss key requirements of a molecular basis for the generation and stabilization of polarity and identify ezrin/E-cadherin, PAR proteins, and Cdx2 as plausible key molecular players. I also discuss the idea of a network process operating to build cell allocations progressively into committed differences. Finally, this review critically considers the possibility of developmental information being encoded within the oocyte and zygote. No final decision can be reached on a mechanism of action underlying any encoded information, but a cell interaction process model is preferred over one that relies solely on differential inheritance.
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Affiliation(s)
- Martin H Johnson
- Department of Physiology, Development, and Neuroscience and Center for Trophoblast Research, The Anatomy School, Cambridge CB2 3DY, United Kingdom.
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Wen J, Zhang H, Li G, Mao G, Chen X, Wang J, Guo M, Mu X, Ouyang H, Zhang M, Xia G. PAR6, a potential marker for the germ cells selected to form primordial follicles in mouse ovary. PLoS One 2009; 4:e7372. [PMID: 19809506 PMCID: PMC2753645 DOI: 10.1371/journal.pone.0007372] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 09/15/2009] [Indexed: 11/18/2022] Open
Abstract
Partitioning-defective proteins (PAR) are detected to express mainly in the cytoplast, and play an important role in cell polarity. However, we showed here that PAR6, one kind of PAR protein, was localized in the nuclei of mouse oocytes that formed primordial follicles during the perinatal period, suggesting a new role of PAR protein. It is the first time we found that, in mouse fetal ovaries, PAR6 appeared in somatic cell cytoplasm and fell weak when somatic cells invaded germ cell cysts at 17.5 days post coitus (dpc). Meanwhile, the expression of PAR6 was observed in cysts, and became strong in the nuclei of some germ cells at 19.5 dpc and all primordial follicular oocytes at 3 day post parturition (dpp), and then obviously declined when the primordial follicles entered the folliculogenic growth phase. During the primordial follicle pool foundation, the number of PAR6 positive germ cells remained steady and was consistent with that of formed follicles at 3 dpp. There were no TUNEL (apoptosis examination) positive germ cells stained with PAR6 at any time studied. The number of follicles significantly declined when 15.5 dpc ovaries were treated with the anti-PAR6 antibody and PAR6 RNA interference. Carbenoxolone (CBX, a known blocker of gap junctions) inhibited the expression of PAR6 in germ cells and the formation of follicles. Our results suggest that PAR6 could be used as a potential marker of germ cells for the primordial follicle formation, and the expression of PAR6 by a gap junction-dependent process may contribute to the formation of primordial follicles and the maintenance of oocytes at the diplotene stage.
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Affiliation(s)
- Jing Wen
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Hua Zhang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Ge Li
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Guanping Mao
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Xiufen Chen
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Jianwei Wang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Meng Guo
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Xinyi Mu
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Hong Ouyang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
| | - Meijia Zhang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
- * E-mail: (MZ); (GX)
| | - Guoliang Xia
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, Agricultural University, Beijing, People's Republic of China
- * E-mail: (MZ); (GX)
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Abstract
Mouse oocytes undergo polarization during meiotic maturation, and this polarization is essential for asymmetric cell divisions that maximize retention of maternal components required for early development. Without conventional centrosomes, the meiotic spindle has less focused poles and is barrel-shaped. The migration of meiotic spindles to the cortex is accompanied by a local reorganization and polarization of the cortex. LGN is a conserved protein involved in cell polarity and regulation of spindle organization. In the present study, we characterized the localization dynamics of LGN during mouse oocyte maturation and analyzed the effects of LGN upregulation and downregulation on meiotic spindle organization. At the germinal vesicle stage, LGN is distributed both cytoplasmically and at the cortex. During maturation, LGN localizes to the meiotic spindle apparatus and cortical LGN becomes less concentrated at the actin cap region. Excessive LGN induces meiotic spindle organization defects by elongating the spindle and enhancing pole focusing, whereas depletion of LGN by RNA interference results in meiotic spindle deformation and chromosome misalignment. Furthermore, the N-terminus of LGN has the ability of full-length LGN to regulate spindle organization, whereas the C-terminus of LGN controls cortical localization and polarization. Our results reveal that LGN is cortically polarized in mouse oocytes and is critical for meiotic spindle organization.
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Deng M, Li R. Sperm chromatin-induced ectopic polar body extrusion in mouse eggs after ICSI and delayed egg activation. PLoS One 2009; 4:e7171. [PMID: 19787051 PMCID: PMC2746308 DOI: 10.1371/journal.pone.0007171] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 08/26/2009] [Indexed: 12/05/2022] Open
Abstract
Meiotic chromosomes in an oocyte are not only a maternal genome carrier but also provide a positional signal to induce cortical polarization and define asymmetric meiotic division of the oocyte, resulting in polar body extrusion and haploidization of the maternal genome. The meiotic chromosomes play dual function in determination of meiosis: 1) organizing a bipolar spindle formation and 2) inducing cortical polarization and assembly of a distinct cortical cytoskeleton structure in the overlying cortex for polar body extrusion. At fertilization, a sperm brings exogenous paternal chromatin into the egg, which induces ectopic cortical polarization at the sperm entry site and leads to a cone formation, known as fertilization cone. Here we show that the sperm chromatin-induced fertilization cone formation is an abortive polar body extrusion due to lack of spindle induction by the sperm chromatin during fertilization. If experimentally manipulating the fertilization process to allow sperm chromatin to induce both cortical polarization and spindle formation, the fertilization cone can be converted into polar body extrusion. This suggests that sperm chromatin is also able to induce polar body extrusion, like its maternal counterpart. The usually observed cone formation instead of ectopic polar body extrusion induced by sperm chromatin during fertilization is due to special sperm chromatin compaction which restrains it from rapid spindle induction and therefore provides a protective mechanism to prevent a possible paternal genome loss during ectopic polar body extrusion.
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Affiliation(s)
- Manqi Deng
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- * E-mail: (MD); (RL)
| | - Rong Li
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- * E-mail: (MD); (RL)
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Actin filaments: key players in the control of asymmetric divisions in mouse oocytes. Biol Cell 2009; 101:69-76. [PMID: 19076067 DOI: 10.1042/bc20080003] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Meiotic maturation is characterized by the succession of two asymmetric divisions each giving rise to a small polar body and a large oocyte. These highly asymmetric divisions are characteristic of meiosis in higher organisms. They allow most of the maternal stores to be retained in the oocyte, a vital property for further embryo development. In mouse oocytes, the asymmetry is ensured by the migration and the anchoring of the division spindle to the cortex in meiosis I and by its anchoring to the cortex in meiosis II. In addition, and subsequent to this off-centre positioning of the spindle, a differentiation of the cortex overhanging the chromosomes takes place and is necessary for the extrusion of small polar bodies. In the present review, we will emphasize the role of the actin cytoskeleton in the control of spindle positioning, spindle anchoring to the cortex and cortical differentiation.
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Azoury J, Lee KW, Georget V, Rassinier P, Leader B, Verlhac MH. Spindle positioning in mouse oocytes relies on a dynamic meshwork of actin filaments. Curr Biol 2008; 18:1514-9. [PMID: 18848445 DOI: 10.1016/j.cub.2008.08.044] [Citation(s) in RCA: 231] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 07/23/2008] [Accepted: 08/14/2008] [Indexed: 10/21/2022]
Abstract
Female meiosis in higher organisms consists of highly asymmetric divisions, which retain most maternal stores in the oocyte for embryo development. Asymmetric partitioning of the cytoplasm results from the spindle's "off-center" positioning, which, in mouse oocytes, depends mainly on actin filaments [1, 2]. This is a unique situation compared to most systems, in which spindle positioning requires interactions between astral microtubules and cortical actin filaments [3]. Formin 2, a straight-actin-filament nucleator, is required for the first meiotic spindle migration to the cortex and cytokinesis in mouse oocytes [4, 5]. Although the requirement for actin filaments in the control of spindle positioning is well established in this model, no one has been able to detect them in the cytoplasm [6]. Through the expression of an F-actin-specific probe and live confocal microscopy, we show the presence of a cytoplasmic actin meshwork, organized by Formin 2, that controls spindle migration. In late meiosis I, these filaments organize into a spindle-like F-actin structure, which is connected to the cortex. At anaphase, global reorganization of this meshwork allows polar-body extrusion. In addition, using actin-YFP, our FRAP analysis confirms the presence of a highly dynamic cytoplasmic actin meshwork that is tightly regulated in time and space.
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Affiliation(s)
- Jessica Azoury
- Unité Mixte de Recherche 7622, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, Paris, France
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39
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Simonova OB, Vorontsova JE. Source of asymmetry in ontogeny: Early polarization of the germline cyst and oocyte in Drosophila. RUSS J GENET+ 2008. [DOI: 10.1134/s1022795408090019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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Baluch DP, Capco DG. GSK3β mediates acentromeric spindle stabilization by activated PKCζ. Dev Biol 2008; 317:46-58. [DOI: 10.1016/j.ydbio.2008.01.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 01/25/2008] [Accepted: 01/30/2008] [Indexed: 11/28/2022]
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41
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Jones KT. Meiosis in oocytes: predisposition to aneuploidy and its increased incidence with age. Hum Reprod Update 2007; 14:143-58. [PMID: 18084010 DOI: 10.1093/humupd/dmm043] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mammalian oocytes begin meiosis in the fetal ovary, but only complete it when fertilized in the adult reproductive tract. This review examines the cell biology of this protracted process: from entry of primordial germ cells into meiosis to conception. The defining feature of meiosis is two consecutive cell divisions (meiosis I and II) and two cell cycle arrests: at the germinal vesicle (GV), dictyate stage of prophase I and at metaphase II. These arrests are spanned by three key events, the focus of this review: (i) passage from mitosis to GV arrest during fetal life, regulated by retinoic acid; (ii) passage through meiosis I and (iii) completion of meiosis II following fertilization, both meiotic divisions being regulated by cyclin-dependent kinase (CDK1) activity. Meiosis I in human oocytes is associated with an age-related high rate of chromosomal mis-segregation, such as trisomy 21 (Down's syndrome), resulting in aneuploid conceptuses. Although aneuploidy is likely to be multifactorial, oocytes from older women may be predisposed to be becoming aneuploid as a consequence of an age-long decline in the cohesive ties holding chromosomes together. Such loss goes undetected by the oocyte during meiosis I either because its ability to respond and block division also deteriorates with age, or as a consequence of being inherently unable to respond to the types of segregation defects induced by cohesion loss.
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Affiliation(s)
- Keith T Jones
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle, NE2 4HH, UK.
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Ninomiya Y, Ichinose S. Subcellular distribution of mitochondrial ribosomal RNA in the mouse oocyte and zygote. PLoS One 2007; 2:e1241. [PMID: 18043748 PMCID: PMC2082410 DOI: 10.1371/journal.pone.0001241] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 11/05/2007] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial ribosomal RNAs (mtrRNAs) have been reported to translocate extra-mitochondrially and localize to the germ cell determinant of oocytes and zygotes in some metazoa except mammals. To address whether the mtrRNAs also localize in the mammals, expression and distribution of mitochondrion-encoded RNAs in the mouse oocytes and zygotes was examined by whole-mount in situ hybridization (ISH). Both 12S and 16S rRNAs were predominantly distributed in the animal hemisphere of the mature oocyte. This distribution pattern was rearranged toward the second polar body in zygotes after fertilization. The amount of mtrRNAs decreased around first cleavage, remained low during second cleavage and increased after third cleavage. Staining intensity of the 12S rRNA was weaker than that of the 16S rRNA throughout the examined stages. Similar distribution dynamics of the 16S rRNA was observed in strontium-activated haploid parthenotes, suggesting the distribution rearrangement does not require a component from sperm. The distribution of 16S rRNAs did not coincide with that of mitochondrion-specific heat shock protein 70, suggesting that the mtrRNA is translocated from mitochondria. The ISH-scanning electron microscopy confirms the extra-mitochondrial mtrRNA in the mouse oocyte. Chloramphenicol (CP) treatment of late pronuclear stage zygotes perturbed first cleavage as judged by the greater than normal disparity in size of blastomeres of 2-cell conceptuses. Two-third of the CP-treated zygotes arrested at either 2-cell or 3-cell stage even after the CP was washed out. These findings indicate that the extra-mitochondrial mtrRNAs are localized in the mouse oocyte and implicated in correct cytoplasmic segregation into blastomeres through cleavages of the zygote.
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Affiliation(s)
- Youichirou Ninomiya
- Mammalian Development Laboratory, Department of Zoology, University of Oxford, Oxford, United Kingdom.
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43
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Lee PN, Kumburegama S, Marlow HQ, Martindale MQ, Wikramanayake AH. Asymmetric developmental potential along the animal–vegetal axis in the anthozoan cnidarian, Nematostella vectensis, is mediated by Dishevelled. Dev Biol 2007; 310:169-86. [PMID: 17716645 DOI: 10.1016/j.ydbio.2007.05.040] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 05/21/2007] [Accepted: 05/29/2007] [Indexed: 11/16/2022]
Abstract
The relationship between egg polarity and the adult body plan is well understood in many bilaterians. However, the evolutionary origins of embryonic polarity are not known. Insight into the evolution of polarity will come from understanding the ontogeny of polarity in non-bilaterian forms, such as cnidarians. We examined how the axial properties of the starlet sea anemone, Nematostella vectensis (Anthozoa, Cnidaria), are established during embryogenesis. Egg-cutting experiments and sperm localization show that Nematostella eggs are only fertilized at the animal pole. Vital marking experiments demonstrate that the egg animal pole corresponds to the sites of first cleavage and gastrulation, and the oral pole of the adult. Embryo separation experiments demonstrate an asymmetric segregation of developmental potential along the animal-vegetal axis prior to the 8-cell stage. We demonstrate that Dishevelled (Dsh) plays an important role in mediating this asymmetric segregation of developmental fate. Although NvDsh mRNA is ubiquitously expressed during embryogenesis, the protein is associated with the female pronucleus at the animal pole in the unfertilized egg, becomes associated with the unipolar first cleavage furrow, and remains enriched in animal pole blastomeres. Our results suggest that at least one mechanism for Dsh enrichment at the animal pole is through its degradation at the vegetal pole. Functional studies reveal that NvDsh is required for specifying embryonic polarity and endoderm by stabilizing beta-catenin in the canonical Wnt signaling pathway. The localization of Dsh to the animal pole in Nematostella and two other anthozoan cnidarians (scleractinian corals) provides a possible explanation for how the site of gastrulation has changed in bilaterian evolution while other axial components of development have remained the same and demonstrates that modifications of the Wnt signaling pathway have been used to pattern a wide variety of metazoan embryos.
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Affiliation(s)
- Patricia N Lee
- Kewalo Marine Lab, Pacific Biosciences Research Center/University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA
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44
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Assémat E, Bazellières E, Pallesi-Pocachard E, Le Bivic A, Massey-Harroche D. Polarity complex proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:614-30. [PMID: 18005931 DOI: 10.1016/j.bbamem.2007.08.029] [Citation(s) in RCA: 330] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Revised: 08/21/2007] [Accepted: 08/27/2007] [Indexed: 12/24/2022]
Abstract
The formation of functional epithelial tissues involves the coordinated action of several protein complexes, which together produce a cell polarity axis and develop cell-cell junctions. During the last decade, the notion of polarity complexes emerged as the result of genetic studies in which a set of genes was discovered first in Caenorhabditis elegans and then in Drosophila melanogaster. In epithelial cells, these complexes are responsible for the development of the apico-basal axis and for the construction and maintenance of apical junctions. In this review, we focus on apical polarity complexes, namely the PAR3/PAR6/aPKC complex and the CRUMBS/PALS1/PATJ complex, which are conserved between species and along with a lateral complex, the SCRIBBLE/DLG/LGL complex, are crucial to the formation of apical junctions such as tight junctions in mammalian epithelial cells. The exact mechanisms underlying their tight junction construction and maintenance activities are poorly understood, and it is proposed to focus in this review on establishing how these apical polarity complexes might regulate epithelial cell morphogenesis and functions. In particular, we will present the latest findings on how these complexes regulate epithelial homeostasis.
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Affiliation(s)
- Emeline Assémat
- Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR 6216 et Université de la Méditerranée, Parc Scientifique et Technologique de Luminy, Case 907, 13288 Marseille Cedex 09, France
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Cui XS, Li XY, Kim NH. Cdc42 is implicated in polarity during meiotic resumption and blastocyst formation in the mouse. Mol Reprod Dev 2007; 74:785-94. [PMID: 17154294 DOI: 10.1002/mrd.20571] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cell division cycle 42 (Cdc42), a member of the Rho family of small guanosine triphosphatase (GTPase) proteins, regulates multiple cell functions, including: motility, proliferation, apoptosis, and cell morphology. In order to obtain insight into the role of Cdc42 in meiotic resumption and embryo development, we first evaluated its gene expression levels in mouse oocytes and embryos during in vitro development. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed high-expression levels in GV stage oocytes that steadily decreased up to the 2-cell (2C) stage embryo, and then expression increased during morulae and blastocyst formation. Indirect Immunocytochemistry also showed protein synthesis of CDC42 in the mouse oocytes and early embryos. Introducing small interference RNA (siRNA) of Cdc42 into germinal vesicle stage oocytes or zygotes specifically reduced both mRNA expression and protein synthesis of CDC42 in in vitro developed metaphase II oocytes and early embryos. Meiotic maturation and cytoskeleton assembly were significantly altered following siRNA injection into germinal vesicle stage oocytes. Injection of siRNA into the zygote did not affect cleavage or cell numbers in morulae, but significantly decreased in vitro development to the morula or blastocyst. These findings suggest that gene expression of Cdc42 is involved in meiotic resumption and blastocyst formation in the mouse, possibly through maintaining polarity.
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Affiliation(s)
- Xiang-Shun Cui
- National Research Laboratory of Molecular Embryology, Department of Animal Sciences, Chungbuk National University, Seoul, Korea
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46
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Halet G, Carroll J. Rac activity is polarized and regulates meiotic spindle stability and anchoring in mammalian oocytes. Dev Cell 2007; 12:309-17. [PMID: 17276347 DOI: 10.1016/j.devcel.2006.12.010] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 11/23/2006] [Accepted: 12/19/2006] [Indexed: 01/24/2023]
Abstract
Mammalian meiotic divisions are asymmetrical and generate a large oocyte and two small polar bodies. This asymmetry results from the anchoring of the meiotic spindle to the oocyte cortex and subsequent cortical reorganization, but the mechanisms involved are poorly understood. We investigated the role of Rac in oocyte meiosis by using a fluorescent reporter for Rac-GTP. We find that Rac-GTP is polarized in the cortex overlying the meiotic spindle. Polarization of Rac activation occurs during spindle migration and is promoted by the proximity of chromatin to the cortex. Inhibition of Rac during oocyte maturation caused a permanent block at prometaphase I and spindle elongation. In metaphase II-arrested oocytes, Rac inhibition caused the spindle to detach from the cortex and prevented polar body emission after activation. These results demonstrate that Rac-GTP plays a major role in oocyte meiosis, via the regulation of spindle stability and anchoring to the cortex.
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Affiliation(s)
- Guillaume Halet
- Department of Physiology, University College London, Gower Street, London WC1E 6BT, United Kingdom.
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47
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Park HO, Bi E. Central roles of small GTPases in the development of cell polarity in yeast and beyond. Microbiol Mol Biol Rev 2007; 71:48-96. [PMID: 17347519 PMCID: PMC1847380 DOI: 10.1128/mmbr.00028-06] [Citation(s) in RCA: 323] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
SUMMARY The establishment of cell polarity is critical for the development of many organisms and for the function of many cell types. A large number of studies of diverse organisms from yeast to humans indicate that the conserved, small-molecular-weight GTPases function as key signaling proteins involved in cell polarization. The budding yeast Saccharomyces cerevisiae is a particularly attractive model because it displays pronounced cell polarity in response to intracellular and extracellular cues. Cells of S. cerevisiae undergo polarized growth during various phases of their life cycle, such as during vegetative growth, mating between haploid cells of opposite mating types, and filamentous growth upon deprivation of nutrition such as nitrogen. Substantial progress has been made in deciphering the molecular basis of cell polarity in budding yeast. In particular, it becomes increasingly clear how small GTPases regulate polarized cytoskeletal organization, cell wall assembly, and exocytosis at the molecular level and how these GTPases are regulated. In this review, we discuss the key signaling pathways that regulate cell polarization during the mitotic cell cycle and during mating.
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Affiliation(s)
- Hay-Oak Park
- Department of Molecular Genetics, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA.
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48
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Cui XS, Li XY, Shen XH, Bae YJ, Kang JJ, Kim NH. Transcription profile in mouse four-cell, morula, and blastocyst: Genes implicated in compaction and blastocoel formation. Mol Reprod Dev 2007; 74:133-43. [PMID: 16998848 DOI: 10.1002/mrd.20483] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To gain insight into early embryo development, we utilized microarray technology to compare gene expression profiles in four-cell (4C), morula (MO), and blastocyst (BL) stage embryos. Differences in spot intensities were normalized, and grouped by using Avadis Prophetic software platform (version 3.3, Strand Genomics Ltd.) and categories were based on the PANTHER and gene ontology (GO) classification system. This technique identified 622 of 7,927 genes as being more highly expressed in MO when compared to 4C (P < 0.05); similarly, we identified 654 of 9,299 genes as being more highly expressed in BL than in MO (P < 0.05). Upregulation of genes for cytoskeletal, cell adhesion, and cell junction proteins were identified in the MO as compared to the 4C stage embryos, this means they could be involved in the cell compaction necessary for the development to the MO. Genes thought to be involved in ion channels, membrane traffic, transfer/carrier proteins, and lipid metabolism were also identified as being expressed at a higher level in the BL stage embryos than in the MO. Real-time RT-PCR was performed to confirm differential expression of selected genes. The identification of the genes being expressed in here will provide insight into the complex gene regulatory networks effecting compaction and blastocoel formation.
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Affiliation(s)
- Xiang-Shun Cui
- Department of Animal Science, Chungbuk National University, Cheongju, Chungbuk, South Korea
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49
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Fichelson P, Huynh JR. Asymmetric divisions of germline cells. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2007; 45:97-120. [PMID: 17585498 DOI: 10.1007/978-3-540-69161-7_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In most vertebrates and invertebrates, germ cells produce female and male gametes after one or several rounds of asymmetric cell division. Germline-specific features are used for the asymmetric segregation of fates, chromosomes and size during gametogenesis. In Drosophila females, for example, a germline-specific organelle called the fusome is used repeatedly to polarize the divisions of germline stem cells for their self-renewal, and during the divisions of cyst cells for the specification of the oocyte among a group of sister cells sharing a common cytoplasm. Later during oogenesis of most species, meiotic divisions produce a striking size asymmetry between a large oocyte and small polar bodies. The strategy used to create this asymmetry may involve the microtubules or the actin microfilaments or both, depending on the considered species. Despite this diversity and species-particularities, recent molecular data suggest that the PAR proteins, which control asymmetric cell division in a wide range of organisms and somatic cell types, could also play an important role at different steps of gametogenesis in many species. Here, we review the asymmetric features of germline cell division, from mitosis of germline stem cells to the extrusion of polar bodies after meiotic divisions.
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Affiliation(s)
- Pierre Fichelson
- Medical Research Council, LMCB, Cell biology unit, University College London, Gower street, WC1E 6BT London, UK
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Na J, Zernicka-Goetz M. Asymmetric positioning and organization of the meiotic spindle of mouse oocytes requires CDC42 function. Curr Biol 2006; 16:1249-54. [PMID: 16782018 DOI: 10.1016/j.cub.2006.05.023] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 05/03/2006] [Accepted: 05/03/2006] [Indexed: 11/24/2022]
Abstract
The mature mammalian oocyte is highly polarized because asymmetrical spindle migration to the oocyte cortex ensures extrusion of small polar bodies in the two meiotic divisions, essential for generation of the large egg. Actin filaments, myosin motors, and formin-2, but not microtubules, are required for spindle migration. Here, we show that Cdc42, a key regulator of cytoskeleton and cell polarity in other systems , is essential for meiotic maturation and oocyte asymmetry. Disrupting CDC42 function by ectopic expression of its GTPase-defective mutants causes both halves of the first meiotic spindle to extend symmetrically toward opposing cortical regions and prevents an asymmetrical division. The elongated spindle has numerous astral-like microtubules, and aPKCzeta, normally associated with the spindle poles, is distributed along its length. Dynactin is displaced from kinetochores, consistently homologous chromosomes do not segregate, and polar body extrusion is prevented. Perturbing the function of aPKCzeta also causes elongation of the meiotic spindle but still permits spindle migration and polar body extrusion. Thus, at least two pathways appear to be downstream of CDC42: one affecting the actin cytoskeleton and required for migration of the meiotic spindle, and a second affecting the spindle microtubules in which aPKCzeta plays a role.
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Affiliation(s)
- Jie Na
- The Wellcome Trust/Cancer Research UK Gurdon Institute of Cancer and Developmental Biology and Department of Genetics, University of Cambridge, Cambridge CB2 1QR, United Kingdom
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