51
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White MD, Zenker J, Bissiere S, Plachta N. Instructions for Assembling the Early Mammalian Embryo. Dev Cell 2018; 45:667-679. [DOI: 10.1016/j.devcel.2018.05.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 01/23/2018] [Accepted: 05/10/2018] [Indexed: 12/15/2022]
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52
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Mihajlović AI, Bruce AW. The first cell-fate decision of mouse preimplantation embryo development: integrating cell position and polarity. Open Biol 2018; 7:rsob.170210. [PMID: 29167310 PMCID: PMC5717349 DOI: 10.1098/rsob.170210] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 10/27/2017] [Indexed: 12/18/2022] Open
Abstract
During the first cell-fate decision of mouse preimplantation embryo development, a population of outer-residing polar cells is segregated from a second population of inner apolar cells to form two distinct cell lineages: the trophectoderm and the inner cell mass (ICM), respectively. Historically, two models have been proposed to explain how the initial differences between these two cell populations originate and ultimately define them as the two stated early blastocyst stage cell lineages. The 'positional' model proposes that cells acquire distinct fates based on differences in their relative position within the developing embryo, while the 'polarity' model proposes that the differences driving the lineage segregation arise as a consequence of the differential inheritance of factors, which exhibit polarized subcellular localizations, upon asymmetric cell divisions. Although these two models have traditionally been considered separately, a growing body of evidence, collected over recent years, suggests the existence of a large degree of compatibility. Accordingly, the main aim of this review is to summarize the major historical and more contemporarily identified events that define the first cell-fate decision and to place them in the context of both the originally proposed positional and polarity models, thus highlighting their functional complementarity in describing distinct aspects of the developmental programme underpinning the first cell-fate decision in mouse embryogenesis.
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Affiliation(s)
- Aleksandar I Mihajlović
- Laboratory of Developmental Biology and Genetics (LDB&G), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Alexander W Bruce
- Laboratory of Developmental Biology and Genetics (LDB&G), Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, Branišovská 31, 37005 České Budějovice, Czech Republic
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53
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Miller A, Hendrich B. Chromatin Remodelling Proteins and Cell Fate Decisions in Mammalian Preimplantation Development. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2018; 229:3-14. [PMID: 29177761 DOI: 10.1007/978-3-319-63187-5_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The very first cell divisions in mammalian embryogenesis produce a ball of cells, each with the potential to form any cell in the developing embryo or placenta. At some point, the embryo produces enough cells that some are located on the outside of the embryo, while others are completely surrounded by other cells. It is at this point that cells undergo the very first lineage commitment event: outer cells form the trophectoderm and lose the potential to form embryonic lineages, while inner cells form the Inner Cell Mass, which retain embryonic potential. Cell identity is defined by gene expression patterns, and gene expression is largely controlled by how the DNA is packaged into chromatin. A number of protein complexes exist which are able to use the energy of ATP to remodel chromatin: that is, to alter the nucleosome topology of chromatin. Here, we summarise the evidence that chromatin remodellers play essential roles in the successful completion of preimplantation development in mammals and describe recent efforts to understand the molecular mechanisms through which chromatin remodellers facilitate the successful completion of the first cell fate decisions in mammalian embryogenesis.
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Affiliation(s)
- Anzy Miller
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | - Brian Hendrich
- Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK. .,Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK.
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54
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Our First Choice: Cellular and Genetic Underpinnings of Trophectoderm Identity and Differentiation in the Mammalian Embryo. Curr Top Dev Biol 2018; 128:59-80. [DOI: 10.1016/bs.ctdb.2017.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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55
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Cell Polarity-Dependent Regulation of Cell Allocation and the First Lineage Specification in the Preimplantation Mouse Embryo. Curr Top Dev Biol 2018; 128:11-35. [DOI: 10.1016/bs.ctdb.2017.10.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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56
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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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57
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Bissiere S, Gasnier M, Alvarez YD, Plachta N. Cell Fate Decisions During Preimplantation Mammalian Development. Curr Top Dev Biol 2017; 128:37-58. [PMID: 29477170 DOI: 10.1016/bs.ctdb.2017.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The early mouse embryo offers a phenomenal system to dissect how changes in the mechanisms controlling cell fate are integrated with morphogenetic events at the single-cell level. New technologies based on live imaging have enabled the discovery of dynamic changes in the regulation of single genes, transcription factors, and epigenetic mechanisms directing early cell fate decision in the early embryo. Here, we review recent progress in linking molecular dynamic events occurring at the level of the single cell in vivo, to some of the key morphogenetic changes regulating early mouse development.
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Affiliation(s)
| | - Maxime Gasnier
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore
| | - Yanina D Alvarez
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore; Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Conicet, Buenos Aires, Argentina
| | - Nicolas Plachta
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore; National University of Singapore, Singapore, Singapore.
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58
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Actomyosin polarisation through PLC-PKC triggers symmetry breaking of the mouse embryo. Nat Commun 2017; 8:921. [PMID: 29030553 PMCID: PMC5640629 DOI: 10.1038/s41467-017-00977-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/09/2017] [Indexed: 11/21/2022] Open
Abstract
Establishment of cell polarity in the mammalian embryo is fundamental for the first cell fate decision that sets aside progenitor cells for both the new organism and the placenta. Yet the sequence of events and molecular mechanism that trigger this process remain unknown. Here, we show that de novo polarisation of the mouse embryo occurs in two distinct phases at the 8-cell stage. In the first phase, an apical actomyosin network is formed. This is a pre-requisite for the second phase, in which the Par complex localises to the apical domain, excluding actomyosin and forming a mature apical cap. Using a variety of approaches, we also show that phospholipase C-mediated PIP2 hydrolysis is necessary and sufficient to trigger the polarisation of actomyosin through the Rho-mediated recruitment of myosin II to the apical cortex. Together, these results reveal the molecular framework that triggers de novo polarisation of the mouse embryo. The molecular trigger that establishes cell polarity in the mammalian embryo is unclear. Here, the authors show that de novo polarisation of the mouse embryo at the 8-cell stage is directed by Phospholipase C and Protein kinase C and occurs in two phases: polarisation of actomyosin followed by the Par complex.
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59
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Boroviak T, Nichols J. Primate embryogenesis predicts the hallmarks of human naïve pluripotency. Development 2017; 144:175-186. [PMID: 28096211 PMCID: PMC5430762 DOI: 10.1242/dev.145177] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Naïve pluripotent mouse embryonic stem cells (ESCs) resemble the preimplantation epiblast and efficiently contribute to chimaeras. Primate ESCs correspond to the postimplantation embryo and fail to resume development in chimaeric assays. Recent data suggest that human ESCs can be ‘reset’ to an earlier developmental stage, but their functional capacity remains ill defined. Here, we discuss how the naïve state is inherently linked to preimplantation epiblast identity in the embryo. We hypothesise that distinctive features of primate development provide stringent criteria to evaluate naïve pluripotency in human and other primate cells. Based on our hypothesis, we define 12 key hallmarks of naïve pluripotency, five of which are specific to primates. These hallmarks may serve as a functional framework to assess human naïve ESCs. Summary: This Hypothesis article highlights several fundamental differences between rodent and primate early development and exploits these to predict key hallmarks of naïve pluripotency in primates.
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Affiliation(s)
- Thorsten Boroviak
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Jennifer Nichols
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.,Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 4BG, UK
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60
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Shi X, Yin Z, Ling B, Wang L, Liu C, Ruan X, Zhang W, Chen L. Rho differentially regulates the Hippo pathway by modulating the interaction between Amot and Nf2 in the blastocyst. Development 2017; 144:3957-3967. [PMID: 28947533 DOI: 10.1242/dev.157917] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 09/20/2017] [Indexed: 01/08/2023]
Abstract
The Hippo pathway modulates the transcriptional activity of Yap to regulate the differentiation of the inner cell mass (ICM) and the trophectoderm (TE) in blastocysts. Yet how Hippo signaling is differentially regulated in ICM and TE cells is poorly understood. Through an inhibitor/activator screen, we have identified Rho as a negative regulator of Hippo in TE cells, and PKA as a positive regulator of Hippo in ICM cells. We further elucidated a novel mechanism by which Rho suppresses Hippo, distinct from the prevailing view that Rho inhibits Hippo signaling through modulating cytoskeleton remodeling and/or cell polarity. Active Rho prevents the phosphorylation of Amot Ser176, thus stabilizing the interaction between Amot and F-actin, and restricting the binding between Amot and Nf2. Moreover, Rho attenuates the interaction between Amot and Nf2 by binding to the coiled-coil domain of Amot. By blocking the association of Nf2 and Amot, Rho suppresses Hippo in TE cells.
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Affiliation(s)
- Xianle Shi
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zixi Yin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Bin Ling
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lingling Wang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xianhui Ruan
- Department of Thyroid and Neck Tumor, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Huanhuxi Road, Ti-Yuan-Bei, Hexi District, Tianjin 300060, China
| | - Weiyu Zhang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lingyi Chen
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, Collaborative Innovation Center for Biotherapy, Tianjin Key Laboratory of Protein Sciences, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics and College of Life Sciences, Nankai University, Tianjin 300071, China
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61
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Maître JL. Mechanics of blastocyst morphogenesis. Biol Cell 2017; 109:323-338. [DOI: 10.1111/boc.201700029] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 06/28/2017] [Accepted: 06/28/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Jean-Léon Maître
- Institut Curie; PSL Research University; CNRS UMR3215, INSERM U934; Paris France
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62
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Campanale JP, Sun TY, Montell DJ. Development and dynamics of cell polarity at a glance. J Cell Sci 2017; 130:1201-1207. [PMID: 28365593 DOI: 10.1242/jcs.188599] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cells exhibit morphological and molecular asymmetries that are broadly categorized as cell polarity. The cell polarity established in early embryos prefigures the macroscopic anatomical asymmetries characteristic of adult animals. For example, eggs and early embryos have polarized distributions of RNAs and proteins that generate global anterior/posterior and dorsal/ventral axes. The molecular programs that polarize embryos are subsequently reused in multiple contexts. Epithelial cells require apical/basal polarity to establish their barrier function. Migrating cells polarize in the direction of movement, creating distinct leading and trailing structures. Asymmetrically dividing stem cells partition different molecules between themselves and their daughter cells. Cell polarity can develop de novo, be maintained through rounds of cell division and be dynamically remodeled. In this Cell Science at a Glance review and poster, we describe molecular asymmetries that underlie cell polarity in several cellular contexts. We highlight multiple developmental systems that first establish cell/developmental polarity, and then maintain it. Our poster showcases repeated use of the Par, Scribble and Crumbs polarity complexes, which drive the development of cell polarity in many cell types and organisms. We then briefly discuss the diverse and dynamic changes in cell polarity that occur during cell migration, asymmetric cell division and in planar polarized tissues.
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Affiliation(s)
- Joseph P Campanale
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Thomas Y Sun
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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63
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Nissen SB, Perera M, Gonzalez JM, Morgani SM, Jensen MH, Sneppen K, Brickman JM, Trusina A. Four simple rules that are sufficient to generate the mammalian blastocyst. PLoS Biol 2017; 15:e2000737. [PMID: 28700688 PMCID: PMC5507476 DOI: 10.1371/journal.pbio.2000737] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 06/09/2017] [Indexed: 11/18/2022] Open
Abstract
Early mammalian development is both highly regulative and self-organizing. It involves the interplay of cell position, predetermined gene regulatory networks, and environmental interactions to generate the physical arrangement of the blastocyst with precise timing. However, this process occurs in the absence of maternal information and in the presence of transcriptional stochasticity. How does the preimplantation embryo ensure robust, reproducible development in this context? It utilizes a versatile toolbox that includes complex intracellular networks coupled to cell-cell communication, segregation by differential adhesion, and apoptosis. Here, we ask whether a minimal set of developmental rules based on this toolbox is sufficient for successful blastocyst development, and to what extent these rules can explain mutant and experimental phenotypes. We implemented experimentally reported mechanisms for polarity, cell-cell signaling, adhesion, and apoptosis as a set of developmental rules in an agent-based in silico model of physically interacting cells. We find that this model quantitatively reproduces specific mutant phenotypes and provides an explanation for the emergence of heterogeneity without requiring any initial transcriptional variation. It also suggests that a fixed time point for the cells' competence of fibroblast growth factor (FGF)/extracellular signal-regulated kinase (ERK) sets an embryonic clock that enables certain scaling phenomena, a concept that we evaluate quantitatively by manipulating embryos in vitro. Based on these observations, we conclude that the minimal set of rules enables the embryo to experiment with stochastic gene expression and could provide the robustness necessary for the evolutionary diversification of the preimplantation gene regulatory network.
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Affiliation(s)
- Silas Boye Nissen
- StemPhys, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Marta Perera
- The Danish Stem Cell Centre, DanStem, University of Copenhagen, Copenhagen, Denmark
| | | | - Sophie M. Morgani
- The Danish Stem Cell Centre, DanStem, University of Copenhagen, Copenhagen, Denmark
| | - Mogens H. Jensen
- StemPhys, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Kim Sneppen
- CMOL, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Joshua M. Brickman
- StemPhys, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- The Danish Stem Cell Centre, DanStem, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (JMB); (AT)
| | - Ala Trusina
- StemPhys, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (JMB); (AT)
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64
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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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65
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Cell-Cycle-Coupled Oscillations in Apical Polarity and Intercellular Contact Maintain Order in Embryonic Epithelia. Curr Biol 2017; 27:1381-1386. [DOI: 10.1016/j.cub.2017.03.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 02/18/2017] [Accepted: 03/27/2017] [Indexed: 11/22/2022]
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66
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Mouse blastomeres acquire ability to divide asymmetrically before compaction. PLoS One 2017; 12:e0175032. [PMID: 28362853 PMCID: PMC5376319 DOI: 10.1371/journal.pone.0175032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 03/20/2017] [Indexed: 11/23/2022] Open
Abstract
The mouse preimplantation embryo generates the precursors of trophectoderm (TE) and inner cell mass (ICM) during the 8- to 16-cell stage transition, when the apico-basal polarized blastomeres undergo divisions that give rise to cells with different fate. Asymmetric segregation of polar domain at 8–16 cell division generate two cell types, polar cells which adopt an outer position and develop in TE and apolar cells which are allocated to inner position as the precursors of ICM. It is still not know when the blastomeres of 8-cell stage start to be determined to undergo asymmetric division. Here, we analyze the frequency of symmetric and asymmetric divisions of blastomeres isolated from 8-cell stage embryo before and after compaction. Using p-Ezrin as the polarity marker we found that size of blastomeres in 2/16 pairs cannot be used as a criterion for distinguishing symmetric and asymmetric divisions. Our results showed that at early 8-cell stage, before any visible signs of cortical polarity, a subset of blastomeres had been already predestined to divide asymmetrically. We also showed that almost all of 8-cell stage blastomeres isolated from compacted embryo divide asymmetrically, whereas in intact embryos, the frequency of asymmetric divisions is significantly lower. Therefore we conclude that in intact embryo the frequency of symmetric and asymmetric division is regulated by cell-cell interactions.
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67
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Holmes WR, Reyes de Mochel NS, Wang Q, Du H, Peng T, Chiang M, Cinquin O, Cho K, Nie Q. Gene Expression Noise Enhances Robust Organization of the Early Mammalian Blastocyst. PLoS Comput Biol 2017; 13:e1005320. [PMID: 28114387 PMCID: PMC5293272 DOI: 10.1371/journal.pcbi.1005320] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 02/06/2017] [Accepted: 12/19/2016] [Indexed: 12/18/2022] Open
Abstract
A critical event in mammalian embryo development is construction of an inner cell mass surrounded by a trophoectoderm (a shell of cells that later form extraembryonic structures). We utilize multi-scale, stochastic modeling to investigate the design principles responsible for robust establishment of these structures. This investigation makes three predictions, each supported by our quantitative imaging. First, stochasticity in the expression of critical genes promotes cell plasticity and has a critical role in accurately organizing the developing mouse blastocyst. Second, asymmetry in the levels of noise variation (expression fluctuation) of Cdx2 and Oct4 provides a means to gain the benefits of noise-mediated plasticity while ameliorating the potentially detrimental effects of stochasticity. Finally, by controlling the timing and pace of cell fate specification, the embryo temporally modulates plasticity and creates a time window during which each cell can continually read its environment and adjusts its fate. These results suggest noise has a crucial role in maintaining cellular plasticity and organizing the blastocyst. A critical event in mammalian embryo development is construction of a mass of embryonic stem cells surrounded by a distinct shell that later forms the placenta along with other structures. Despite sustained investigation, multiple hypotheses for what is responsible for this organization persist and it remains unclear what is responsible for the robust organization (remarkable ability for embryos to pattern correctly) of these structures. Here, we utilize multi-scale, stochastic modeling along with fluorescence imaging to investigate the factors that contribute to the incredible robustness of this organizational process. Results point to two factors that contribute to this robustness: 1) the timing and pace of cell fate specification and 2) stochastic gene regulatory effects. The former creates a window of time during which each cell can continually read their environment and adjust their gene expressions (and consequently fate) in response to dynamic rearrangements of cells arising from cell divisions and motions. The latter improves cell plasticity, providing the capability for cells to adjust to changes in their local environment. Fluorescence imaging results demonstrate that the magnitude and structure of gene expression variations match those predicted to promote organizational robustness.
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Affiliation(s)
- William R. Holmes
- Department of Physics and Astronomy, Vanderbilt University, Nashville TN, United States of America
| | - Nabora Soledad Reyes de Mochel
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, United States of America
| | - Qixuan Wang
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Mathematics, University of California, Irvine, Irvine, CA, United States of America
| | - Huijing Du
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Mathematics, University of California, Irvine, Irvine, CA, United States of America
| | - Tao Peng
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Mathematics, University of California, Irvine, Irvine, CA, United States of America
| | - Michael Chiang
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, United States of America
| | - Olivier Cinquin
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, United States of America
| | - Ken Cho
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, United States of America
- * E-mail: (QN); (KC)
| | - Qing Nie
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA, United States of America
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, United States of America
- Department of Mathematics, University of California, Irvine, Irvine, CA, United States of America
- * E-mail: (QN); (KC)
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68
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Menchero S, Rayon T, Andreu MJ, Manzanares M. Signaling pathways in mammalian preimplantation development: Linking cellular phenotypes to lineage decisions. Dev Dyn 2016; 246:245-261. [DOI: 10.1002/dvdy.24471] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 11/16/2016] [Accepted: 11/16/2016] [Indexed: 12/20/2022] Open
Affiliation(s)
- Sergio Menchero
- Centro Nacional de Investigaciones Cardiovasculares (CNIC); Madrid Spain
| | - Teresa Rayon
- Centro Nacional de Investigaciones Cardiovasculares (CNIC); Madrid Spain
| | - Maria Jose Andreu
- Centro Nacional de Investigaciones Cardiovasculares (CNIC); Madrid Spain
| | - Miguel Manzanares
- Centro Nacional de Investigaciones Cardiovasculares (CNIC); Madrid Spain
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White MD, Zenker J, Bissiere S, Plachta N. How cells change shape and position in the early mammalian embryo. Curr Opin Cell Biol 2016; 44:7-13. [PMID: 28033492 DOI: 10.1016/j.ceb.2016.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/23/2016] [Accepted: 11/27/2016] [Indexed: 10/20/2022]
Abstract
During preimplantation development, cells of the mammalian embryo must resolve their shape and position to ensure the future viability of the fetus. These initial changes are established as the embryo expands from one to thirty-two cells, and a group of originally spherical cells is transformed into a more polarized structure with distinct cell geometries and lineages. Recent advances in the application of non-invasive imaging technologies have enabled the discovery of mechanisms regulating patterning of the early mammalian embryo. Here, we review recent findings revealing cell protrusions that trigger early changes in cell shape and embryo compaction, and how anisotropies in mechanical forces drive the first spatial segregation of cells in the embryo to form the pluripotent inner mass.
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Affiliation(s)
- Melanie D White
- Institute of Molecular and Cell Biology, A*STAR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Jennifer Zenker
- Institute of Molecular and Cell Biology, A*STAR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Stephanie Bissiere
- Institute of Molecular and Cell Biology, A*STAR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Nicolas Plachta
- Institute of Molecular and Cell Biology, A*STAR, 61 Biopolis Drive, Singapore 138673, Singapore.
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Hadjiantoniou SV, Sean D, Ignacio M, Godin M, Slater GW, Pelling AE. Physical confinement signals regulate the organization of stem cells in three dimensions. J R Soc Interface 2016; 13:20160613. [PMID: 27798278 PMCID: PMC5095220 DOI: 10.1098/rsif.2016.0613] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/05/2016] [Indexed: 01/25/2023] Open
Abstract
During embryogenesis, the spherical inner cell mass (ICM) proliferates in the confined environment of a blastocyst. Embryonic stem cells (ESCs) are derived from the ICM, and mimicking embryogenesis in vitro, mouse ESCs (mESCs) are often cultured in hanging droplets. This promotes the formation of a spheroid as the cells sediment and aggregate owing to increased physical confinement and cell-cell interactions. In contrast, mESCs form two-dimensional monolayers on flat substrates and it remains unclear if the difference in organization is owing to a lack of physical confinement or increased cell-substrate versus cell-cell interactions. Employing microfabricated substrates, we demonstrate that a single geometric degree of physical confinement on a surface can also initiate spherogenesis. Experiment and computation reveal that a balance between cell-cell and cell-substrate interactions finely controls the morphology and organization of mESC aggregates. Physical confinement is thus an important regulatory cue in the three-dimensional organization and morphogenesis of developing cells.
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Affiliation(s)
- Sebastian V Hadjiantoniou
- Department of Biology, University of Ottawa, Gendron Hall, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
| | - David Sean
- Department of Physics, University of Ottawa, MacDonald Hall, 150 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
| | - Maxime Ignacio
- Department of Physics, University of Ottawa, MacDonald Hall, 150 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
| | - Michel Godin
- Department of Physics, University of Ottawa, MacDonald Hall, 150 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
- Department of Mechanical Engineering, University of Ottawa, Site Building, 800 King Edward Avenue, Ottawa, Ontario, Canada K1N 6N5
- Ottawa-Carleton Institute for Biomedical Engineering, Ottawa, Ontario, Canada K1N 6N5
| | - Gary W Slater
- Department of Physics, University of Ottawa, MacDonald Hall, 150 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
| | - Andrew E Pelling
- Department of Biology, University of Ottawa, Gendron Hall, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
- Department of Physics, University of Ottawa, MacDonald Hall, 150 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5
- Institute for Science, University of Ottawa, Society and Policy, Desmarais Building, 55 Laurier Avenue East, Ottawa, Ontario, Canada K1N 6N5
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Rho-associated protein kinase regulates subcellular localisation of Angiomotin and Hippo-signalling during preimplantation mouse embryo development. Reprod Biomed Online 2016; 33:381-90. [PMID: 27430121 DOI: 10.1016/j.rbmo.2016.06.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 06/03/2016] [Accepted: 06/14/2016] [Indexed: 01/14/2023]
Abstract
The differential activity of the Hippo-signalling pathway between the outer- and inner-cell populations of the developing preimplantation mouse embryo directs appropriate formation of trophectoderm and inner cell mass (ICM) lineages. Such distinct signalling activity is under control of intracellular polarization, whereby Hippo-signalling is either supressed in polarized outer cells or activated in apolar inner cells. The central role of apical-basolateral polarization to such differential Hippo-signalling regulation prompted us to reinvestigate the role of potential upstream molecular regulators affecting apical-basolateral polarity. This study reports that the chemical inhibition of Rho-associated kinase (Rock) is associated with failure to form morphologically distinct blastocysts, indicative of compromised trophectoderm differentiation, and defects in the localization of both apical and basolateral polarity factors associated with malformation of tight junctions. Moreover, Rock-inhibition mediates mislocalization of the Hippo-signalling activator Angiomotin (Amot), to the basolateral regions of outer cells and is concomitant with aberrant activation of the pathway. The Rock-inhibition phenotype is mediated by Amot, as RNAi-based Amot knockdown totally rescues the normal suppression of Hippo-signalling in outer cells. In conclusion, Rock, via regulating appropriate apical-basolateral polarization in outer cells, regulates the appropriate activity of the Hippo-signalling pathway, by ensuring correct subcellular localization of Amot protein in outer cells.
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Abstract
The preimplantation development stage of mammalian embryogenesis consists of a series of highly conserved, regulated, and predictable cell divisions. This process is essential to allow the rapid expansion and differentiation of a single-cell zygote into a multicellular blastocyst containing cells of multiple developmental lineages. This period of development, also known as the germinal stage, encompasses several important developmental transitions, which are accompanied by dramatic changes in cell cycle profiles and dynamics. These changes are driven primarily by differences in the establishment and enforcement of cell cycle checkpoints, which must be bypassed to facilitate the completion of essential cell cycle events. Much of the current knowledge in this area has been amassed through the study of knockout models in mice. These mouse models are powerful experimental tools, which have allowed us to dissect the relative dependence of the early embryonic cell cycles on various aspects of the cell cycle machinery and highlight the extent of functional redundancy between members of the same gene family. This chapter will explore the ways in which the cell cycle machinery, their accessory proteins, and their stimuli operate during mammalian preimplantation using mouse models as a reference and how this allows for the usually well-defined stages of the cell cycle to be shaped and transformed during this unique and critical stage of development.
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74
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Leung CY, Zhu M, Zernicka-Goetz M. Polarity in Cell-Fate Acquisition in the Early Mouse Embryo. Curr Top Dev Biol 2016; 120:203-34. [PMID: 27475853 DOI: 10.1016/bs.ctdb.2016.04.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Establishing polarity is a fundamental part of embryogenesis and can be traced back to the earliest developmental stages. It can be achieved in one of two ways: through the preexisting polarization of germ cells before fertilization or via symmetry breaking after fertilization. In mammals, it seems to be the latter, and we will discuss the various cytological and molecular events that lead up to this event, its mechanisms and the consequences. In mammals, the first polarization event occurs in the preimplantation period, when the embryo is but a cluster of cells, free-floating in the oviduct. This provides a unique, autonomous system to study the de novo polarization that is essential to life. In this review, we will cover modern and past studies on the polarization of the early embryo, using the mouse as a model system, as well as hypothesizing the potential implications and functions of the biological events involved.
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Affiliation(s)
- C Y Leung
- University of Cambridge, Cambridge, United Kingdom
| | - M Zhu
- University of Cambridge, Cambridge, United Kingdom
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75
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Lokken AA, Ralston A. The Genetic Regulation of Cell Fate During Preimplantation Mouse Development. Curr Top Dev Biol 2016; 120:173-202. [PMID: 27475852 DOI: 10.1016/bs.ctdb.2016.04.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The adult body is estimated to contain several hundred distinct cell types, each with a specialized physiological function. Failure to maintain cell fate can lead to devastating diseases and cancer, but understanding how cell fates are assigned and maintained during animal development provides new opportunities for human health intervention. The mouse is a premier model for evaluating the genetic regulation of cell fate during development because of the wide variety of tools for measuring and manipulating gene expression levels, the ability to access embryos at desired developmental stages, and the similarities between mouse and human development, particularly during the early stages of development. During the first 3 days of mouse development, the preimplantation embryo sets aside cells that will contribute to the extraembryonic tissues. The extraembryonic tissues are essential for establishing pregnancy and ensuring normal fetal development in both mice and humans. Genetic analyses of mouse preimplantation development have permitted identification of genes that are essential for specification of the extraembryonic lineages. In this chapter, we review the tools and concepts of mouse preimplantation development. We describe genes that are essential for cell fate specification during preimplantation stages, and we describe diverse models proposed to account for the mechanisms of cell fate specification during early development.
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Affiliation(s)
- A A Lokken
- Michigan State University, East Lansing, MI, United States
| | - A Ralston
- Michigan State University, East Lansing, MI, United States.
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76
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Kim HY, Jackson TR, Davidson LA. On the role of mechanics in driving mesenchymal-to-epithelial transitions. Semin Cell Dev Biol 2016; 67:113-122. [PMID: 27208723 DOI: 10.1016/j.semcdb.2016.05.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/12/2016] [Accepted: 05/17/2016] [Indexed: 01/27/2023]
Abstract
The mesenchymal-to-epithelial transition (MET) is an intrinsically mechanical process describing a multi-step progression where autonomous mesenchymal cells gradually become tightly linked, polarized epithelial cells. METs are fundamental to a wide range of biological processes, including the evolution of multicellular organisms, generation of primary and secondary epithelia during development and organogenesis, and the progression of diseases including cancer. In these cases, there is an interplay between the establishment of cell polarity and the mechanics of neighboring cells and microenvironment. In this review, we highlight a spectrum of METs found in normal development as well as in pathological lesions, and provide insight into the critical role mechanics play at each step. We define MET as an independent process, distinct from a reverse-EMT, and propose questions to further explore the cellular and physical mechanisms of MET.
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Affiliation(s)
- Hye Young Kim
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Timothy R Jackson
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Lance A Davidson
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Developmental Biology, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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77
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Chazaud C, Yamanaka Y. Lineage specification in the mouse preimplantation embryo. Development 2016; 143:1063-74. [DOI: 10.1242/dev.128314] [Citation(s) in RCA: 199] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During mouse preimplantation embryo development, totipotent blastomeres generate the first three cell lineages of the embryo: trophectoderm, epiblast and primitive endoderm. In recent years, studies have shown that this process appears to be regulated by differences in cell-cell interactions, gene expression and the microenvironment of individual cells, rather than the active partitioning of maternal determinants. Precisely how these differences first emerge and how they dictate subsequent molecular and cellular behaviours are key questions in the field. As we review here, recent advances in live imaging, computational modelling and single-cell transcriptome analyses are providing new insights into these questions.
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Affiliation(s)
- Claire Chazaud
- Université Clermont Auvergne, Laboratoire GReD, Clermont-Ferrand F-63000, France
- Inserm, UMR1103, Clermont-Ferrand F-63001, France
- CNRS, UMR6293, Clermont-Ferrand F-63001, France
| | - Yojiro Yamanaka
- Goodman Cancer Research Centre, Department of Human Genetics, McGill University, 1160 Pine Avenue West, rm419, Montreal, Quebec, Canada H3A 1A3
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78
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Abstract
Vertebrate neural tube formation is a complex morphogenetic process, which involves hundreds of genes dynamically coordinating various behaviors in different cell populations of neural tissue. The challenge remains to determine the relative contributions of physical forces and biochemical signaling events to neural tube closure and accompanying cell fate specification. Planar cell polarity (PCP) molecules are prime candidate factors for the production of actomyosin-dependent mechanical signals necessary for morphogenesis. Conversely, physical forces may contribute to the polarized distribution of PCP proteins. Understanding mechanosensory and mechanotransducing properties of diverse molecules should help define the direction and amplitude of physical stresses that are critical for neurulation.
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Affiliation(s)
- Sergei Y Sokol
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, USA.
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79
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Toyooka Y, Oka S, Fujimori T. Early preimplantation cells expressing Cdx2 exhibit plasticity of specification to TE and ICM lineages through positional changes. Dev Biol 2016; 411:50-60. [PMID: 26806703 DOI: 10.1016/j.ydbio.2016.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/28/2015] [Accepted: 01/20/2016] [Indexed: 10/22/2022]
Abstract
The establishment of the trophectoderm (TE) and the inner cell mass (ICM) is the first cell lineage segregation to occur in mouse preimplantation development. These two cell lineages arise in a position-dependent manner at the blastocyst stage: the outer cells form TE, which will generate the future placenta, while the inner cells give rise to the ICM, from which the epiblast (EPI) and primitive endoderm (PrE) arise. Previous studies have shown that a portion of cells relocate from the outside position to the inside during this preimplantation stage, but few studies have investigated the correlation between cell relocation and the expression of key transcription factors critical for cell differentiation. To monitor cell movement and the status of the TE-specification pathway in living embryos, we established Cdx2-GFP reporter mice allowing us to visualize the expression of Caudal-type transcriptional factor (Cdx2), a key regulator of the initiation of TE differentiation. Observation of Cdx2-GFP preimplantation embryos by live cell imaging revealed that all cells localized in an initial outer position initiated the expression of Cdx2. Subsequently, cells that changed their position from an outer to an inner position downregulated Cdx2 expression and contributed to the ICM. Finally we showed that internalized cells likely contribute to both the EPI and PrE. Our datas indicate that cells expressing even high levels of Cdx2 can internalize, deactivate an activated TE-specification molecular pathway and integrate into the pluripotent cell population.
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Affiliation(s)
- Yayoi Toyooka
- Division of Embryology, National Institute for Basic Biology, Okazaki, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan.
| | - Sanae Oka
- Division of Embryology, National Institute for Basic Biology, Okazaki, Japan
| | - Toshihiko Fujimori
- Division of Embryology, National Institute for Basic Biology, Okazaki, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan.
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80
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Frankenberg SR, de Barros FR, Rossant J, Renfree MB. The mammalian blastocyst. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 5:210-32. [DOI: 10.1002/wdev.220] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/22/2015] [Accepted: 10/29/2015] [Indexed: 11/10/2022]
Affiliation(s)
| | - Flavia R.O. de Barros
- Program in Developmental and Stem Cell Biology; Peter Gilgan Centre for Research and Learning, Hospital for Sick Children; Toronto Canada
- Department of Molecular Genetics; University of Toronto; Toronto Canada
| | - Janet Rossant
- Program in Developmental and Stem Cell Biology; Peter Gilgan Centre for Research and Learning, Hospital for Sick Children; Toronto Canada
- Department of Molecular Genetics; University of Toronto; Toronto Canada
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81
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Abstract
After a spermatozoon enters an oocyte, maternal factors accumulated in the oocyte reprogram the genomes of the terminally differentiated oocyte and spermatozoon epigenetically and turn the zygote into a totipotent cell, with the capacity to differentiate into all types of somatic cells in a highly organized manner and generate the entire organism, a feature referred to as totipotency. Differentiation of the first lineage begins after three cleavages, when the early embryo compacts and becomes polarized, followed by segregation of the first lineages--the inner cell mass (ICM) and the trophectoderm (TE). To date, a full understanding of the molecular mechanisms that underlie the establishment of totipotency and the ICM/TE lineage segregation remains unclear. In this review, we discuss recent findings in the mechanism of transcriptional regulation networks and signaling pathways in the first lineage separation in the totipotent mouse embryo.
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Affiliation(s)
- Guangming Wu
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Hans R Schöler
- Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.
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82
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Piliszek A, Grabarek JB, Frankenberg SR, Plusa B. Cell fate in animal and human blastocysts and the determination of viability. Mol Hum Reprod 2016; 22:681-690. [DOI: 10.1093/molehr/gaw002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/08/2016] [Indexed: 12/25/2022] Open
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83
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Graham SJ, Zernicka-Goetz M. The Acquisition of Cell Fate in Mouse Development. Curr Top Dev Biol 2016; 117:671-95. [DOI: 10.1016/bs.ctdb.2015.11.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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84
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Bessonnard S, Mesnard D, Constam DB. PC7 and the related proteases Furin and Pace4 regulate E-cadherin function during blastocyst formation. J Cell Biol 2015; 210:1185-97. [PMID: 26416966 PMCID: PMC4586756 DOI: 10.1083/jcb.201503042] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Targeted deletion of PC7 and the related proprotein convertases Furin and Pace4, combined with live imaging of their activities, unmasks their overlapping and complementary functions in morula compaction and ICM formation in mouse blastocysts and in E-cadherin precursor processing. The first cell differentiation in mammalian embryos segregates polarized trophectoderm cells from an apolar inner cell mass (ICM). This lineage decision is specified in compacted morulae by cell polarization and adhesion acting on the Yes-associated protein in the Hippo signaling pathway, but the regulatory mechanisms are unclear. We show that morula compaction and ICM formation depend on PC7 and the related proprotein convertases (PCs) Furin and Pace4 and that these proteases jointly regulate cell–cell adhesion mediated by E-cadherin processing. We also mapped the spatiotemporal activity profiles of these proteases by live imaging of a transgenic reporter substrate in wild-type and PC mutant embryos. Differential inhibition by a common inhibitor revealed that all three PCs are active in inner and outer cells, but in partially nonoverlapping compartments. E-cadherin processing by multiple PCs emerges as a novel mechanism to modulate cell–cell adhesion and fate allocation.
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Affiliation(s)
- Sylvain Bessonnard
- Swiss Federal Institute of Technology in Lausanne, School of Life Sciences, Swiss Institute for Experimental Cancer Research, 1015 Lausanne, Switzerland
| | - Daniel Mesnard
- Swiss Federal Institute of Technology in Lausanne, School of Life Sciences, Swiss Institute for Experimental Cancer Research, 1015 Lausanne, Switzerland
| | - Daniel B Constam
- Swiss Federal Institute of Technology in Lausanne, School of Life Sciences, Swiss Institute for Experimental Cancer Research, 1015 Lausanne, Switzerland
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85
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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: 34] [Impact Index Per Article: 3.8] [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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86
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Moorhouse KS, Gudejko HF, McDougall A, Burgess DR. Influence of cell polarity on early development of the sea urchin embryo. Dev Dyn 2015; 244:1469-84. [PMID: 26293695 PMCID: PMC4715636 DOI: 10.1002/dvdy.24337] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 08/11/2015] [Accepted: 08/13/2015] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Establishment and maintenance of cell polarity is critical for normal embryonic development. Previously, it was thought that the echinoderm embryo remained relatively unpolarized until the first asymmetric division at the 16-cell stage. Here, we analyzed roles of the cell polarity regulators, the PAR complex proteins, and how their disruption in early development affects later developmental milestones. RESULTS We found that PAR6, aPKC, and CDC42 localize to the apical cortex as early as the 2-cell stage and that this localization is retained through the gastrula stage. Of interest, PAR1 also colocalizes with these apical markers through the gastrula stage. Additionally, PAR1 was found to be in complex with aPKC, but not PAR6. PAR6, aPKC, and CDC42 are anchored in the cortical actin cytoskeleton by assembled myosin. Furthermore, assembled myosin was found to be necessary to maintain proper PAR6 localization through subsequent cleavage divisions. Interference with myosin assembly prevented the embryos from reaching the blastula stage, while transient disruptions of either actin or microtubules did not have this effect. CONCLUSIONS These observations suggest that disruptions of the polarity in the early embryo can have a significant impact on the ability of the embryo to reach later critical stages in development.
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Affiliation(s)
- Kathleen S. Moorhouse
- Department of Biology, Boston College, Chestnut Hill, Massachusetts
- Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Heather F.M. Gudejko
- Department of Biology, Boston College, Chestnut Hill, Massachusetts
- Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Alex McDougall
- UMR 7009, UPMC Sorbonne Universités, Centre National de la Recherche (CNRS), Observatoire Océanologique, 181 Chemin du Lazaret, 06230 Villefranche-sur-Mer, France
| | - David R. Burgess
- Department of Biology, Boston College, Chestnut Hill, Massachusetts
- Marine Biological Laboratory, Woods Hole, Massachusetts
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87
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The first two cell-fate decisions of preimplantation mouse embryo development are not functionally independent. Sci Rep 2015; 5:15034. [PMID: 26461180 PMCID: PMC4602213 DOI: 10.1038/srep15034] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 09/02/2015] [Indexed: 11/10/2022] Open
Abstract
During mouse preimplantation embryo development, three distinct cell lineages are formed, represented by the differentiating trophectoderm (TE), primitive endoderm (PrE) and the pluripotent epiblast (EPI). Classically, lineage derivation has been presented as a two-step process whereby outer TE cells are first segregated from inner-cell mass (ICM), followed by ICM refinement into either the PrE or EPI. As ICM founders can be produced following the fourth or fifth cleavage divisions, their potential to equally contribute to EPI and PrE is contested. Thus, modelling the early sequestration of ICM founders from TE-differentiation after the fourth cleavage division, we examined ICM lineage contribution of varying sized cell clones unable to initiate TE-differentiation. Such TE-inhibited ICM cells do not equally contribute to EPI and PrE and are significantly biased to form EPI. This bias is not caused by enhanced expression of the EPI marker Nanog, nor correlated with reduced apical polarity but associated with reduced expression of PrE-related gene transcripts (Dab2 and Lrp2) and down-regulation of plasma membrane associated Fgfr2. Our results favour a unifying model were the three cell lineages are guided in an integrated, yet flexible, fate decision centred on relative exposure of founder cells to TE-differentiative cues.
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88
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Eckert JJ, Velazquez MA, Fleming TP. Cell signalling during blastocyst morphogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 843:1-21. [PMID: 25956293 DOI: 10.1007/978-1-4939-2480-6_1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Blastocyst morphogenesis is prepared for even before fertilisation. Information stored within parental gametes can influence both maternal and embryonic gene expression programmes after egg activation at fertilisation. A complex network of intrinsic, cell-cell mediated and extrinsic, embryo-environment signalling mechanisms operates throughout cleavage, compaction and cavitation. These signalling events not only ensure developmental progression, cell differentiation and lineage allocation to inner cell mass (embryo proper) and trophectoderm (future extraembryonic lineages) but also provide a degree of developmental plasticity ensuring survival in prevailing conditions by adaptive responses. Indeed, many cellular functions including differentiation, metabolism, gene expression and gene expression regulation are subject to plasticity with short- or long-term consequences even into adult life. The interplay between intrinsic and extrinsic signals impacting on blastocyst morphogenesis is becoming clearer. This has been best studied in the mouse which will be the focus of this chapter but translational significance to human and domestic animal embryology will be a focus in future years.
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Affiliation(s)
- Judith J Eckert
- Human Development and Health, Faculty of Medicine, University of Southampton, SO16 6YD, Southampton, UK
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89
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Jedrusik A. Making the first decision: lessons from the mouse. Reprod Med Biol 2015; 14:135-150. [PMID: 29259411 PMCID: PMC5715835 DOI: 10.1007/s12522-015-0206-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 03/31/2015] [Indexed: 01/06/2023] Open
Abstract
Pre-implantation development encompasses a period of 3-4 days over which the mammalian embryo has to make its first decision: to separate the pluripotent inner cell mass (ICM) from the extra-embryonic epithelial tissue, the trophectoderm (TE). The ICM gives rise to tissues mainly building the body of the future organism, while the TE contributes to the extra-embryonic tissues that support embryo development after implantation. This review provides an overview of the cellular and molecular mechanisms that control the critical aspects of this first decision, and highlights the role of critical events, namely zytotic genome activation, compaction, polarization, asymmetric cell divisions, formation of the blastocyst cavity and expression of key transcription factors.
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Affiliation(s)
- Agnieszka Jedrusik
- Wellcome Trust/CR UK Gurdon InstituteTennis Court RoadCB2 1QNCambridgeUK
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeDowning StreetCB2 3DYCambridgeUK
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90
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Biggins JS, Royer C, Watanabe T, Srinivas S. Towards understanding the roles of position and geometry on cell fate decisions during preimplantation development. Semin Cell Dev Biol 2015; 47-48:74-9. [PMID: 26349030 PMCID: PMC4683091 DOI: 10.1016/j.semcdb.2015.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 01/15/2023]
Abstract
The first lineage segregation event in mouse embryos produces two separate cell populations: inner cell mass and trophectoderm. This is understood to be brought about by cells sensing their position within the embryo and differentiating accordingly. The cellular and molecular underpinnings of this process remain under investigation and have variously been considered to be completely stochastic or alternately, subject to some predisposition set up at fertilisation or before. Here, we consider these views in light of recent publications, discuss the possible role of cell geometry and mechanical forces in this process and describe how modelling could contribute in addressing this issue.
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Affiliation(s)
- John S Biggins
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Christophe Royer
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Tomoko Watanabe
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Shankar Srinivas
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, UK.
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91
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Leung CY, Zernicka-Goetz M. Mapping the journey from totipotency to lineage specification in the mouse embryo. Curr Opin Genet Dev 2015; 34:71-6. [PMID: 26343010 DOI: 10.1016/j.gde.2015.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 08/03/2015] [Accepted: 08/11/2015] [Indexed: 10/23/2022]
Abstract
Understanding the past is to understand the present. Mammalian life, with all its complexity comes from a humble beginning of a single fertilized egg cell. Achieving this requires an enormous diversification of cellular function, the majority of which is generated through a series of cellular decisions during embryogenesis. The first decisions are made as the embryo prepares for implantation, a process that will require specialization of extra-embryonic lineages while preserving an embryonic one. In this mini-review, we will focus on the mouse as a mammalian model and discuss recent advances in the decision making process of the early embryo.
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Affiliation(s)
- Chuen Yan Leung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge CB2 3DY, United Kingdom
| | - Magdalena Zernicka-Goetz
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge CB2 3DY, United Kingdom.
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92
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Samarage C, White M, Álvarez Y, Fierro-González J, Henon Y, Jesudason E, Bissiere S, Fouras A, Plachta N. Cortical Tension Allocates the First Inner Cells of the Mammalian Embryo. Dev Cell 2015; 34:435-47. [DOI: 10.1016/j.devcel.2015.07.004] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 05/18/2015] [Accepted: 07/13/2015] [Indexed: 01/08/2023]
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93
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Single cells get together: High-resolution approaches to study the dynamics of early mouse development. Semin Cell Dev Biol 2015; 47-48:92-100. [PMID: 26183190 DOI: 10.1016/j.semcdb.2015.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 06/17/2015] [Accepted: 06/19/2015] [Indexed: 11/22/2022]
Abstract
Embryonic development is a complex and highly dynamic process during which individual cells interact with one another, adopt different identities and organize themselves in three-dimensional space to generate an entire organism. Recent technical developments in genomics and high-resolution quantitative imaging are making it possible to study cellular populations at single-cell resolution and begin to integrate different inputs, for example genetic, physical and chemical factors, that affect cell differentiation over spatial and temporal scales. The preimplantation mouse embryo allows the analysis of cell fate decisions in vivo with high spatiotemporal resolution. In this review we highlight how the application of live imaging and single-cell resolution analysis pipelines is providing an unprecedented level of insight on the processes that shape the earliest stages of mammalian development.
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94
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Abstract
Formation of a eutherian mammal requires concurrent establishment of embryonic and extraembryonic lineages. The functions of the trophectoderm and primitive endoderm are to enable implantation in the maternal uterus, axis specification and delivery of nutrients. The pluripotent epiblast represents the founding cell population of the embryo proper, which is protected from ectopic and premature differentiation until it is required to respond to inductive cues to form the fetus. While positional information plays a major role in specifying the trophoblast lineage, segregation of primitive endoderm from epiblast depends upon gradual acquisition of transcriptional identity, directed but not initiated by fibroblast growth factor (FGF) signalling. Following early cleavage divisions and formation of the blastocyst, cells of the inner cell mass lose totipotency. Developing epiblast cells transiently attain the state of naive pluripotency and competence to self-renew in vitro as embryonic stem cells and in vivo by means of diapause. This property is lost after implantation as the epiblast epithelializes and becomes primed in preparation for gastrulation and subsequent organogenesis.
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Affiliation(s)
- Thorsten Boroviak
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Jennifer Nichols
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
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95
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Bedzhov I, Graham SJL, Leung CY, Zernicka-Goetz M. Developmental plasticity, cell fate specification and morphogenesis in the early mouse embryo. Philos Trans R Soc Lond B Biol Sci 2015; 369:rstb.2013.0538. [PMID: 25349447 PMCID: PMC4216461 DOI: 10.1098/rstb.2013.0538] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A critical point in mammalian development is when the early embryo implants into its mother's uterus. This event has historically been difficult to study due to the fact that it occurs within the maternal tissue and therefore is hidden from view. In this review, we discuss how the mouse embryo is prepared for implantation and the molecular mechanisms involved in directing and coordinating this crucial event. Prior to implantation, the cells of the embryo are specified as precursors of future embryonic and extra-embryonic lineages. These preimplantation cell fate decisions rely on a combination of factors including cell polarity, position and cell–cell signalling and are influenced by the heterogeneity between early embryo cells. At the point of implantation, signalling events between the embryo and mother, and between the embryonic and extraembryonic compartments of the embryo itself, orchestrate a total reorganization of the embryo, coupled with a burst of cell proliferation. New developments in embryo culture and imaging techniques have recently revealed the growth and morphogenesis of the embryo at the time of implantation, leading to a new model for the blastocyst to egg cylinder transition. In this model, pluripotent cells that will give rise to the fetus self-organize into a polarized three-dimensional rosette-like structure that initiates egg cylinder formation.
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Affiliation(s)
- Ivan Bedzhov
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Sarah J L Graham
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Chuen Yan Leung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Magdalena Zernicka-Goetz
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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96
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Klompstra D, Anderson DC, Yeh JY, Zilberman Y, Nance J. An instructive role for C. elegans E-cadherin in translating cell contact cues into cortical polarity. Nat Cell Biol 2015; 17:726-35. [PMID: 25938815 PMCID: PMC4449804 DOI: 10.1038/ncb3168] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 03/25/2015] [Indexed: 12/15/2022]
Abstract
Cell contacts provide spatial cues that polarize early embryos and epithelial cells. The homophilic adhesion protein E-cadherin is required for contact-induced polarity in many cells. However, it is debated whether E-cadherin functions instructively as a spatial cue, or permissively by ensuring adequate adhesion so that cells can sense other contact signals. In Caenorhabditis elegans, contacts polarize early embryonic cells by recruiting the RhoGAP PAC-1 to the adjacent cortex, inducing PAR protein asymmetry. Here we show that the E-cadherin HMR-1, which is dispensable for adhesion, functions together with the α-catenin HMP-1, the p120 catenin JAC-1, and the previously uncharacterized linker PICC-1 (human CCDC85A-C) to bind PAC-1 and recruit it to contacts. Mislocalizing the HMR-1 intracellular domain to contact-free surfaces draws PAC-1 to these sites and depolarizes cells, demonstrating an instructive role for HMR-1 in polarization. Our findings identify an E-cadherin-mediated pathway that translates cell contacts into cortical polarity by directly recruiting a symmetry-breaking factor to the adjacent cortex.
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Affiliation(s)
- Diana Klompstra
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Dorian C. Anderson
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Justin Y. Yeh
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Yuliya Zilberman
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Jeremy Nance
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
- Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
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97
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Sasaki H. Position- and polarity-dependent Hippo signaling regulates cell fates in preimplantation mouse embryos. Semin Cell Dev Biol 2015; 47-48:80-7. [PMID: 25986053 DOI: 10.1016/j.semcdb.2015.05.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 11/25/2022]
Abstract
During the preimplantation stage, mouse embryos establish two cell lineages by the time of early blastocyst formation: the trophectoderm (TE) and the inner cell mass (ICM). Historical models have proposed that the establishment of these two lineages depends on the cell position within the embryo (e.g., the positional model) or cell polarization along the apicobasal axis (e.g., the polarity model). Recent findings have revealed that the Hippo signaling pathway plays a central role in the cell fate-specification process: active and inactive Hippo signaling in the inner and outer cells promote ICM and TE fates, respectively. Intercellular adhesion activates, while apicobasal polarization suppresses Hippo signaling, and a combination of these processes determines the spatially regulated activation of the Hippo pathway in 32-cell-stage embryos. Therefore, there is experimental evidence in favor of both positional and polarity models. At the molecular level, phosphorylation of the Hippo-pathway component angiomotin at adherens junctions (AJs) in the inner (apolar) cells activates the Lats protein kinase and triggers Hippo signaling. In the outer cells, however, cell polarization sequesters Amot from basolateral AJs and suppresses activation of the Hippo pathway. Other mechanisms, including asymmetric cell division and Notch signaling, also play important roles in the regulation of embryonic development. In this review, I discuss how these mechanisms cooperate with the Hippo signaling pathway during cell fate-specification processes.
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Affiliation(s)
- Hiroshi Sasaki
- Laboratory for Embryogenesis, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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98
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Lorthongpanich C, Issaragrisil S. Emerging Role of the Hippo Signaling Pathway in Position Sensing and Lineage Specification in Mammalian Preimplantation Embryos. Biol Reprod 2015; 92:143. [PMID: 25947059 DOI: 10.1095/biolreprod.114.127803] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 04/29/2015] [Indexed: 12/29/2022] Open
Abstract
In preimplantation mouse embryos, the first lineage differentiation takes place in the 8- to 16-cell-stage embryo and results in formation of the trophectoderm (TE) and inner cell mass (ICM), which will give rise to the trophoblast of the placenta and the embryo proper, respectively. Although, it is widely accepted that positioning of a cell within the embryo influences lineage differentiation, the mechanism underlying differential lineage differentiation and how it involves cell position are largely unknown. Interestingly, novel cues from the Hippo pathway have been recently demonstrated in the preimplantation mouse embryo. Unlike the mechanisms reported from epithelium-cultured cells, the Hippo pathway was found to be responsible for translating positional information to lineage specification through a position-sensing mechanism. Disruption of Hippo pathway-component genes in early embryos results in failure of lineage specification and failure of postimplantation development. In this review, we discuss the unique role of the Hippo signaling pathway in early embryo development and its role in lineage specification. Understanding the activity and regulation of the Hippo pathway may offer new insights into other areas of developmental biology that evolve from understanding of this cell-fate specification in the early embryonic cell.
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Affiliation(s)
- Chanchao Lorthongpanich
- Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Surapol Issaragrisil
- Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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99
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Cao Z, Carey TS, Ganguly A, Wilson CA, Paul S, Knott JG. Transcription factor AP-2γ induces early Cdx2 expression and represses HIPPO signaling to specify the trophectoderm lineage. Development 2015; 142:1606-15. [PMID: 25858457 DOI: 10.1242/dev.120238] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/06/2015] [Indexed: 01/31/2023]
Abstract
Cell fate decisions are fundamental to the development of multicellular organisms. In mammals the first cell fate decision involves segregation of the pluripotent inner cell mass and the trophectoderm, a process regulated by cell polarity proteins, HIPPO signaling and lineage-specific transcription factors such as CDX2. However, the regulatory mechanisms that operate upstream to specify the trophectoderm lineage have not been established. Here we report that transcription factor AP-2γ (TFAP2C) functions as a novel upstream regulator of Cdx2 expression and position-dependent HIPPO signaling in mice. Loss- and gain-of-function studies and promoter analysis revealed that TFAP2C binding to an intronic enhancer is required for activation of Cdx2 expression during early development. During the 8-cell to morula transition TFAP2C potentiates cell polarity to suppress HIPPO signaling in the outside blastomeres. TFAP2C depletion triggered downregulation of PARD6B, loss of apical cell polarity, disorganization of F-actin, and activation of HIPPO signaling in the outside blastomeres. Rescue experiments using Pard6b mRNA restored cell polarity but only partially corrected position-dependent HIPPO signaling, suggesting that TFAP2C negatively regulates HIPPO signaling via multiple pathways. Several genes involved in regulation of the actin cytoskeleton (including Rock1, Rock2) were downregulated in TFAP2C-depleted embryos. Inhibition of ROCK1 and ROCK2 activity during the 8-cell to morula transition phenocopied TFAP2C knockdown, triggering a loss of position-dependent HIPPO signaling and decrease in Cdx2 expression. Altogether, these results demonstrate that TFAP2C facilitates trophectoderm lineage specification by functioning as a key regulator of Cdx2 transcription, cell polarity and position-dependent HIPPO signaling.
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Affiliation(s)
- Zubing Cao
- Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Timothy S Carey
- Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Avishek Ganguly
- Department of Pathology and Laboratory Medicine, Institute of Reproductive Health and Regenerative Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Catherine A Wilson
- Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
| | - Soumen Paul
- Department of Pathology and Laboratory Medicine, Institute of Reproductive Health and Regenerative Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Jason G Knott
- Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA
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100
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Carneiro K, de Brito JM, Rossi MID. Development by three-dimensional approaches and four-dimensional imaging: to the knowledge frontier and beyond. ACTA ACUST UNITED AC 2015; 105:1-8. [PMID: 25789860 DOI: 10.1002/bdrc.21089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Many advances have been taken on elucidating embryonic development and tissue homeostasis and repair by the use of experimental strategies that preserve the three-dimensional (3D) organization and allow quantitative analysis of images over time (four-dimensional). Ranging from the understanding about the relationship between blastomeres and the events that take place during gastrulation by the use of time-lapse imaging through 3D cultures that mimic organogenesis, the advances in this area are of critical value. The studies on embryonic development without disrupting the original architecture and the development of 3D organoid cultures pave a new avenue for unprecedented experimental advances that will positively impact the emergence of new treatments applying regenerative principles for both tissue repair and organ transplant.
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Affiliation(s)
- Katia Carneiro
- Biomedical Institute of Sciences, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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