1
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Junyent S, Meglicki M, Vetter R, Mandelbaum R, King C, Patel EM, Iwamoto-Stohl L, Reynell C, Chen DY, Rubino P, Arrach N, Paulson RJ, Iber D, Zernicka-Goetz M. The first two blastomeres contribute unequally to the human embryo. Cell 2024; 187:2838-2854.e17. [PMID: 38744282 DOI: 10.1016/j.cell.2024.04.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 12/06/2023] [Accepted: 04/22/2024] [Indexed: 05/16/2024]
Abstract
Retrospective lineage reconstruction of humans predicts that dramatic clonal imbalances in the body can be traced to the 2-cell stage embryo. However, whether and how such clonal asymmetries arise in the embryo is unclear. Here, we performed prospective lineage tracing of human embryos using live imaging, non-invasive cell labeling, and computational predictions to determine the contribution of each 2-cell stage blastomere to the epiblast (body), hypoblast (yolk sac), and trophectoderm (placenta). We show that the majority of epiblast cells originate from only one blastomere of the 2-cell stage embryo. We observe that only one to three cells become internalized at the 8-to-16-cell stage transition. Moreover, these internalized cells are more frequently derived from the first cell to divide at the 2-cell stage. We propose that cell division dynamics and a cell internalization bottleneck in the early embryo establish asymmetry in the clonal composition of the future human body.
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Affiliation(s)
- Sergi Junyent
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Maciej Meglicki
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Roman Vetter
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel 4058, Switzerland; Swiss Institute of Bioinformatics (SIB), Mattenstrasse 26, 4058 Basel, Switzerland
| | - Rachel Mandelbaum
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California, Los Angeles, CA 90033, USA
| | - Catherine King
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Ekta M Patel
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Lisa Iwamoto-Stohl
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Clare Reynell
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Dong-Yuan Chen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Patrizia Rubino
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California, Los Angeles, CA 90033, USA
| | | | - Richard J Paulson
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Southern California, Los Angeles, CA 90033, USA
| | - Dagmar Iber
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel 4058, Switzerland; Swiss Institute of Bioinformatics (SIB), Mattenstrasse 26, 4058 Basel, Switzerland
| | - Magdalena Zernicka-Goetz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.
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2
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Zernicki-Glover S, Stanislawska N, Patel EM, Kavanagh YH, Meglicki M. Blastomere size in the human 2-cell embryo predicts the division order that leads to imbalanced lineage contribution to the future body. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001181. [PMID: 38841597 PMCID: PMC11151110 DOI: 10.17912/micropub.biology.001181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/09/2024] [Accepted: 04/19/2024] [Indexed: 06/07/2024]
Abstract
Retrospective tracing of somatic mutations predicted that most cells in the human body could be traced back to a single cell of the 2-cell stage embryo. Accordingly, a recent prospective study of the developmental trajectory of blastomeres in human embryos confirmed that progeny of the first 2-cell stage blastomere to divide generates more epiblast cells (future body). How the 2-cell blastomeres differ is unknown. Here, we show that 2-cell stage blastomeres in human embryos are asymmetric; they differ in size and the bigger blastomere divides first to 4-cell stage. We propose that this asymmetry might originate differences in cell fate.
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Affiliation(s)
| | | | - Ekta M. Patel
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States
| | - Yu Hua Kavanagh
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, United Kingdom
| | - Maciej Meglicki
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, United Kingdom
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3
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Reardon S. Human embryos embrace asymmetry to form the body. Nature 2024:10.1038/d41586-024-01403-y. [PMID: 38740917 DOI: 10.1038/d41586-024-01403-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
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4
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Guo Y, Li TD, Modzelewski AJ, Siomi H. Retrotransposon renaissance in early embryos. Trends Genet 2024; 40:39-51. [PMID: 37949723 DOI: 10.1016/j.tig.2023.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 10/13/2023] [Accepted: 10/16/2023] [Indexed: 11/12/2023]
Abstract
Despite being the predominant genetic elements in mammalian genomes, retrotransposons were often dismissed as genomic parasites with ambiguous biological significance. However, recent studies reveal their functional involvement in early embryogenesis, encompassing crucial processes such as zygotic genome activation (ZGA) and cell fate decision. This review underscores the paradigm shift in our understanding of retrotransposon roles during early preimplantation development, as well as their rich functional reservoir that is exploited by the host to provide cis-regulatory elements, noncoding RNAs, and functional proteins. The rapid advancement in long-read sequencing, low input multiomics profiling, advanced in vitro systems, and precise gene editing techniques encourages further dissection of retrotransposon functions that were once obscured by the intricacies of their genomic footprints.
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Affiliation(s)
- Youjia Guo
- Department of Molecular Biology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan
| | - Ten D Li
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA
| | - Andrew J Modzelewski
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA.
| | - Haruhiko Siomi
- Department of Molecular Biology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan; Human Biology Microbiome Quantum Research Center (WPI-Bio2Q), Keio University, Tokyo 160-8582, Japan.
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5
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Lamba A, Zernicka-Goetz M. The role of polarization and early heterogeneities in the mammalian first cell fate decision. Curr Top Dev Biol 2023; 154:169-196. [PMID: 37100517 DOI: 10.1016/bs.ctdb.2023.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The first cell fate decision is the process by which cells of an embryo take on distinct lineage identities for the first time, representing the beginning of patterning during development. In mammals, this process separates an embryonic inner cell mass lineage (future new organism) from an extra-embryonic trophectoderm lineage (future placenta), and in the mouse, this is classically attributed to the consequences of apical-basal polarity. The mouse embryo acquires this polarity at the 8-cell stage, indicated by cap-like protein domains on the apical surface of each cell; those cells which retain polarity over subsequent divisions are specified as trophectoderm, and the rest as inner cell mass. Recent research has advanced our knowledge of this process - this review will discuss mechanisms behind the establishment of polarity and distribution of the apical domain, different factors affecting the first cell fate decision including heterogeneities between cells of the very early embryo, and the conservation of developmental mechanisms across species, including human.
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Affiliation(s)
- Adiyant Lamba
- Mammalian Embryo and Stem Cell Group, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Magdalena Zernicka-Goetz
- Mammalian Embryo and Stem Cell Group, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom; Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
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6
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Silvestri G, Turner KJ, Silcock JL, Sinclair KD, Griffin DK. Effects of single or serial embryo splitting on the development and morphokinetics of in vitro produced bovine embryos. THE EUROPEAN ZOOLOGICAL JOURNAL 2022. [DOI: 10.1080/24750263.2022.2077994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- G. Silvestri
- School of Biosciences, University of Kent, Canterbury, UK
| | - K. J. Turner
- School of Biosciences, University of Kent, Canterbury, UK
| | - J. L. Silcock
- School of Biosciences, University of Kent, Canterbury, UK
| | - K. D. Sinclair
- Schools of Biosciences and Veterinary Medicine and Sciences, University of Nottingham, Sutton Bonington, UK
| | - D. K. Griffin
- School of Biosciences, University of Kent, Canterbury, UK
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7
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Ramalho JJ, Jones VAS, Mutte S, Weijers D. Pole position: How plant cells polarize along the axes. THE PLANT CELL 2022; 34:174-192. [PMID: 34338785 PMCID: PMC8774072 DOI: 10.1093/plcell/koab203] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/30/2021] [Indexed: 05/10/2023]
Abstract
Having a sense of direction is a fundamental cellular trait that can determine cell shape, division orientation, or function, and ultimately the formation of a functional, multicellular body. Cells acquire and integrate directional information by establishing discrete subcellular domains along an axis with distinct molecular profiles, a process known as cell polarization. Insight into the principles and mechanisms underlying cell polarity has been propelled by decades of extensive research mostly in yeast and animal models. Our understanding of cell polarity establishment in plants, which lack most of the regulatory molecules identified in other eukaryotes, is more limited, but significant progress has been made in recent years. In this review, we explore how plant cells coordinately establish stable polarity axes aligned with the organ axes, highlighting similarities in the molecular logic used to polarize both plant and animal cells. We propose a classification system for plant cell polarity events and nomenclature guidelines. Finally, we provide a deep phylogenetic analysis of polar proteins and discuss the evolution of polarity machineries in plants.
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Affiliation(s)
| | | | - Sumanth Mutte
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6703WE Wageningen, The Netherlands
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8
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Jin H, Han Y, Wang H, Li JXH, Shen W, Zhang L, Chen L, Jia S, Yuan P, Chen H, Meng A. The second polar body contributes to the fate asymmetry in the mouse embryo. Natl Sci Rev 2022; 9:nwac003. [PMID: 35919785 PMCID: PMC9337984 DOI: 10.1093/nsr/nwac003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 12/02/2022] Open
Abstract
The polar bodies (PBs) are extruded microcells during oocyte meiosis and generally regarded as inessentials for embryonic development. Therefore, PBs have been widely used as important materials for pre-implantation genetic diagnosis in human. Here we report that the second PB (PB2) in the mouse zygote may play roles in cell-fate specification and post-implantation development. A subset of mRNAs encoding pluripotency-related factors are enriched in PB2. Nascent proteins may be synthesized in PB2 after fertilization and transport from PB2 to the zygote before the two-cell stage. The PB2-attached blastomere (pbB) at the two-cell stage, compared to the other blastomere (npbB), likely contributes more descendants to the inner cell mass (ICM) lineage in the blastocyst. Removal of PB2 from the zygote or transient blockage of material exchange between PB2 and the zygote by nocodazole treatment appears to cause a loss of the ICM fate bias of pbB. PB2 removal or nocodazole treatment also results in abnormal post-implantation development. Injection of PB2 lysate into pbB of PB2-removed two-cell-stage embryos may reset the cell-fate preference and rescue post-implantation development. Our data collectively suggest that PB2 would demarcate the earliest cell-fate asymmetry of the mouse zygote and be required for post-implantation development.
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Affiliation(s)
- Hongbin Jin
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Yang Han
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Huasong Wang
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - J Xiao He Li
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Weimin Shen
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Lin Zhang
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Luxi Chen
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Shunji Jia
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
| | - Ping Yuan
- Center for Reproductive Genetics and Reproductive Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou510120, China
| | - Hui Chen
- Center for Reproductive Genetics and Reproductive Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou510120, China
| | - Anming Meng
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing100084, China
- Center for Reproductive Genetics and Reproductive Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou510120, China
- Guangzhou Laboratory, Guangzhou510320, China
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9
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Mori M, Yao T, Mishina T, Endoh H, Tanaka M, Yonezawa N, Shimamoto Y, Yonemura S, Yamagata K, Kitajima TS, Ikawa M. RanGTP and the actin cytoskeleton keep paternal and maternal chromosomes apart during fertilization. J Cell Biol 2021; 220:e202012001. [PMID: 34424312 PMCID: PMC8404465 DOI: 10.1083/jcb.202012001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 06/18/2021] [Accepted: 08/06/2021] [Indexed: 11/22/2022] Open
Abstract
Zygotes require two accurate sets of parental chromosomes, one each from the mother and the father, to undergo normal embryogenesis. However, upon egg-sperm fusion in vertebrates, the zygote has three sets of chromosomes, one from the sperm and two from the egg. The zygote therefore eliminates one set of maternal chromosomes (but not the paternal chromosomes) into the polar body through meiosis, but how the paternal chromosomes are protected from maternal meiosis has been unclear. Here we report that RanGTP and F-actin dynamics prevent egg-sperm fusion in proximity to maternal chromosomes. RanGTP prevents the localization of Juno and CD9, egg membrane proteins that mediate sperm fusion, at the cell surface in proximity to maternal chromosomes. Following egg-sperm fusion, F-actin keeps paternal chromosomes away from maternal chromosomes. Disruption of these mechanisms causes the elimination of paternal chromosomes during maternal meiosis. This study reveals a novel critical mechanism that prevents aneuploidy in zygotes.
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Affiliation(s)
- Masashi Mori
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Tatsuma Yao
- Research and Development Center, Fuso Pharmaceutical Industries, Ltd., Osaka, Japan
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Tappei Mishina
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Hiromi Endoh
- Laboratory for Ultrastructural Research, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Masahito Tanaka
- Physics and Cell Biology Laboratory, National Institute of Genetics & Department of Genetics, SOKENDAI University, Kanagawa, Japan
| | - Nao Yonezawa
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Yuta Shimamoto
- Physics and Cell Biology Laboratory, National Institute of Genetics & Department of Genetics, SOKENDAI University, Kanagawa, Japan
| | - Shigenobu Yonemura
- Laboratory for Ultrastructural Research, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
- Department of Cell Biology, Tokushima University Graduate School of Medical Science, Tokushima, Japan
| | - Kazuo Yamagata
- Graduate School of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Tomoya S. Kitajima
- Laboratory for Chromosome Segregation, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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10
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Bizzotto S, Dou Y, Ganz J, Doan RN, Kwon M, Bohrson CL, Kim SN, Bae T, Abyzov A, Park PJ, Walsh CA. Landmarks of human embryonic development inscribed in somatic mutations. Science 2021; 371:1249-1253. [PMID: 33737485 DOI: 10.1126/science.abe1544] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
Although cell lineage information is fundamental to understanding organismal development, very little direct information is available for humans. We performed high-depth (250×) whole-genome sequencing of multiple tissues from three individuals to identify hundreds of somatic single-nucleotide variants (sSNVs). Using these variants as "endogenous barcodes" in single cells, we reconstructed early embryonic cell divisions. Targeted sequencing of clonal sSNVs in different organs (about 25,000×) and in more than 1000 cortical single cells, as well as single-nucleus RNA sequencing and single-nucleus assay for transposase-accessible chromatin sequencing of ~100,000 cortical single cells, demonstrated asymmetric contributions of early progenitors to extraembryonic tissues, distinct germ layers, and organs. Our data suggest onset of gastrulation at an effective progenitor pool of about 170 cells and about 50 to 100 founders for the forebrain. Thus, mosaic mutations provide a permanent record of human embryonic development at very high resolution.
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Affiliation(s)
- Sara Bizzotto
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Yanmei Dou
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Javier Ganz
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Ryan N Doan
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA
| | - Minseok Kwon
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Craig L Bohrson
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA
| | - Sonia N Kim
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,PhD Program in Biological and Biomedical Sciences, Harvard University, Boston, MA 02115, USA
| | - Taejeong Bae
- Department of Health Sciences Research, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Alexej Abyzov
- Department of Health Sciences Research, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA. .,Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA. .,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
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11
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Fasching L, Jang Y, Tomasi S, Schreiner J, Tomasini L, Brady MV, Bae T, Sarangi V, Vasmatzis N, Wang Y, Szekely A, Fernandez TV, Leckman JF, Abyzov A, Vaccarino FM. Early developmental asymmetries in cell lineage trees in living individuals. Science 2021; 371:1245-1248. [PMID: 33737484 DOI: 10.1126/science.abe0981] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
Mosaic mutations can be used to track cell lineages in humans. We used cell cloning to analyze embryonic cell lineages in two living individuals and a postmortem human specimen. Of 10 reconstructed postzygotic divisions, none resulted in balanced contributions of daughter lineages to tissues. In both living individuals, one of two lineages from the first cleavage was dominant across tissues, with 90% frequency in blood. We propose that the efficiency of DNA repair contributes to lineage imbalance. Allocation of lineages in postmortem brain correlated with anterior-posterior axis, associating lineage history with cell fate choices in embryos. We establish a minimally invasive framework for defining cell lineages in any living individual, which paves the way for studying their relevance in health and disease.
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Affiliation(s)
- Liana Fasching
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Yeongjun Jang
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Simone Tomasi
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | | | - Livia Tomasini
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Melanie V Brady
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Taejeong Bae
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Vivekananda Sarangi
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Nikolaos Vasmatzis
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Yifan Wang
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Anna Szekely
- Department of Neurology, Yale University, New Haven, CT 06520, USA
| | - Thomas V Fernandez
- Child Study Center, Yale University, New Haven, CT 06520, USA.,Department of Psychiatry, Yale University, New Haven, CT 06520, USA
| | - James F Leckman
- Child Study Center, Yale University, New Haven, CT 06520, USA.,Department of Psychiatry, Yale University, New Haven, CT 06520, USA
| | - Alexej Abyzov
- Department of Quantitative Health Sciences, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA.
| | - Flora M Vaccarino
- Child Study Center, Yale University, New Haven, CT 06520, USA. .,Department of Neuroscience, Yale University, New Haven, CT 06520, USA.,Yale Kavli Institute for Neuroscience, New Haven, CT 06520, USA
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12
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Casser E, Wdowik S, Israel S, Witten A, Schlatt S, Nordhoff V, Boiani M. Differences in blastomere totipotency in 2-cell mouse embryos are a maternal trait mediated by asymmetric mRNA distribution. Mol Hum Reprod 2020; 25:729-744. [PMID: 31504820 PMCID: PMC6884417 DOI: 10.1093/molehr/gaz051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 07/05/2019] [Accepted: 08/14/2019] [Indexed: 12/13/2022] Open
Abstract
It is widely held that the first two blastomeres of mammalian embryos are equally totipotent and that this totipotency belongs to the group of regulative properties. However, this interpretation neglects an important aspect: evidence only came from successful monozygotic twins which can speak only for those pairs of half-embryos that are able to regulate in the first place. Are the frequently occurring incomplete pairs simply an artefact, or do they represent a real difference, be it in the imperfect blastomere's ability to regulate growth or in the distribution of any compound X that constrains regulation? Using the model system of mouse embryos bisected at the 2-cell stage after fertilization, we present evidence that the interblastomere differences evade regulation by external factors and are already latent in oocytes. Specifically, an interblastomere imbalance of epiblast production persists under the most diverse culture conditions and applies to the same extent in parthenogenetic counterparts. As a result, cases in which twin blastocysts continued to develop in only one member account for 65 and 57% of zygotic and parthenogenetic pairs, respectively. The interblastomere imbalance is related to the subcellular distribution of gene products, as documented for the epiblast-related gene Cops3, using mRNA FISH in super-resolution mode confocal microscopy. Blastomere patterns of Cops3 mRNA distribution are α-amanitin-resistant. Thus, the imbalance originates not from de novo transcription, but from influences which are effective before fertilisation. These data expose previously unrecognized limits of regulative capacities of 2-cell stage blastomeres and point to aspects of cytoplasmic organization of the mouse oocyte that segregate unequally to blastomeres during cleavage.
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Affiliation(s)
- E Casser
- Max Planck Institute for Molecular Biomedicine, Muenster, Germany
| | - S Wdowik
- Max Planck Institute for Molecular Biomedicine, Muenster, Germany
| | - S Israel
- Max Planck Institute for Molecular Biomedicine, Muenster, Germany
| | - A Witten
- Core Genomic Facility, University Hospital Muenster, Muenster, Germany
| | - S Schlatt
- Centre for Reproductive Medicine and Andrology, University Hospital Muenster, Muenster, Germany
| | - V Nordhoff
- Centre for Reproductive Medicine and Andrology, University Hospital Muenster, Muenster, Germany
| | - M Boiani
- Max Planck Institute for Molecular Biomedicine, Muenster, Germany
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13
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Wang K, Chen H, Miao Y, Bayer M. Square one: zygote polarity and early embryogenesis in flowering plants. CURRENT OPINION IN PLANT BIOLOGY 2020; 53:128-133. [PMID: 31727540 DOI: 10.1016/j.pbi.2019.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/27/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
In the last two decades, work on auxin signaling has helped to understand many aspects of the fundamental process underlying the specification of tissue types in the plant embryo. However, the immediate steps after fertilization including the polarization of the zygote and the initial body axis formation remained poorly understood. Valuable insight into these enigmatic processes has been gained by studying fertilization in grasses. Recent technical advances in transcriptomics of developing embryos with high spatial and temporal resolution give an emerging picture of the rapid changes of the zygotic developmental program. Together with the use of live imaging of novel fluorescent marker lines, these data are now the basis of unraveling the very first steps of the embryonic patterning process.
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Affiliation(s)
- Kai Wang
- Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Houming Chen
- Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Yingjing Miao
- Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Martin Bayer
- Max Planck Institute for Developmental Biology, Department of Cell Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany.
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14
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Molè MA, Weberling A, Zernicka-Goetz M. Comparative analysis of human and mouse development: From zygote to pre-gastrulation. Curr Top Dev Biol 2019; 136:113-138. [PMID: 31959285 DOI: 10.1016/bs.ctdb.2019.10.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Development of the mammalian embryo begins with formation of the totipotent zygote during fertilization. This initial cell is able to give rise to every embryonic tissue of the developing organism as well as all extra-embryonic lineages, such as the placenta and the yolk sac, which are essential for the initial patterning and support growth of the fetus until birth. As the embryo transits from pre- to post-implantation, major structural and transcriptional changes occur within the embryonic lineage to set up the basis for the subsequent phase of gastrulation. Fine-tuned coordination of cell division, morphogenesis and differentiation is essential to ultimately promote assembly of the future fetus. Here, we review the current knowledge of mammalian development of both mouse and human focusing on morphogenetic processes leading to the onset of gastrulation, when the embryonic anterior-posterior axis becomes established and the three germ layers start to be specified.
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15
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Simerly CR, Takahashi D, Jacoby E, Castro C, Hartnett C, Hewitson L, Navara C, Schatten G. Fertilization and Cleavage Axes Differ In Primates Conceived By Conventional (IVF) Versus Intracytoplasmic Sperm Injection (ICSI). Sci Rep 2019; 9:15282. [PMID: 31653971 PMCID: PMC6814755 DOI: 10.1038/s41598-019-51815-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/03/2019] [Indexed: 12/14/2022] Open
Abstract
With nearly ten million babies conceived globally, using assisted reproductive technologies, fundamental questions remain; e.g., How do the sperm and egg DNA unite? Does ICSI have consequences that IVF does not? Here, pronuclear and mitotic events in nonhuman primate zygotes leading to the establishment of polarity are investigated by multidimensional time-lapse video microscopy and immunocytochemistry. Multiplane videos after ICSI show atypical sperm head displacement beneath the oocyte cortex and eccentric para-tangential pronuclear alignment compared to IVF zygotes. Neither fertilization procedure generates incorporation cones. At first interphase, apposed pronuclei align obliquely to the animal-vegetal axis after ICSI, with asymmetric furrows assembling from the male pronucleus. Furrows form within 30° of the animal pole, but typically, not through the ICSI injection site. Membrane flow drives polar bodies and the ICSI site into the furrow. Mitotic spindle imaging suggests para-tangential pronuclear orientation, which initiates random spindle axes and minimal spindle:cortex interactions. Parthenogenetic pronuclei drift centripetally and assemble astral spindles lacking cortical interactions, leading to random furrows through the animal pole. Conversely, androgenotes display cortex-only pronuclear interactions mimicking ICSI. First cleavage axis determination in primates involves dynamic cortex-microtubule interactions among male pronuclei, centrosomal microtubules, and the animal pole, but not the ICSI site.
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Affiliation(s)
- Calvin R Simerly
- Pittsburgh Development Center, Division of Developmental & Regenerative Medicine, and Obstetrics-Gynecology-Reproductive Sciences, Cell Biology, and Bioengineering, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 204 Craft Avenue Pittsburgh, Pennsylvania, 15213, USA
| | - Diana Takahashi
- Division of Cardiometabolic Health, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, 97006, USA
| | - Ethan Jacoby
- CCRM Houston Main Center Memorial City, 929 Gessner Rd, Suite 2300, Houston, Texas, 77024, USA
| | - Carlos Castro
- Pittsburgh Development Center, Division of Developmental & Regenerative Medicine, and Obstetrics-Gynecology-Reproductive Sciences, Cell Biology, and Bioengineering, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 204 Craft Avenue Pittsburgh, Pennsylvania, 15213, USA
| | - Carrie Hartnett
- Pittsburgh Development Center, Division of Developmental & Regenerative Medicine, and Obstetrics-Gynecology-Reproductive Sciences, Cell Biology, and Bioengineering, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 204 Craft Avenue Pittsburgh, Pennsylvania, 15213, USA
| | - Laura Hewitson
- The Johnson Center for Child Health and Development, Austin, Texas, 78701, USA
| | - Christopher Navara
- Department of Biology, South Texas Center for Emerging Infectious Disease, University of Texas at San Antonio, San Antonio, Texas, 78249, USA
| | - Gerald Schatten
- Pittsburgh Development Center, Division of Developmental & Regenerative Medicine, and Obstetrics-Gynecology-Reproductive Sciences, Cell Biology, and Bioengineering, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 204 Craft Avenue Pittsburgh, Pennsylvania, 15213, USA.
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16
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Cofre J, Saalfeld K, Abdelhay E. Cancer as an Embryological Phenomenon and Its Developmental Pathways: A Hypothesis regarding the Contribution of the Noncanonical Wnt Pathway. ScientificWorldJournal 2019; 2019:4714781. [PMID: 30940992 PMCID: PMC6421044 DOI: 10.1155/2019/4714781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 12/18/2018] [Accepted: 01/29/2019] [Indexed: 02/07/2023] Open
Abstract
For gastrulation to occur in human embryos, a mechanism that simultaneously regulates many different processes, such as cell differentiation, proliferation, migration, and invasion, is required to consistently and effectively create a human being during embryonic morphogenesis. The striking similarities in the processes of cancer and gastrulation have prompted speculation regarding the developmental pathways involved in their regulation. One of the fundamental requirements for the developmental pathways in gastrulation and cancer is the ability to respond to environmental stimuli, and it has been proposed that the Kaiso and noncanonical Wnt pathways participate in the mechanisms regulating these developmental pathways. In particular, these pathways might also explain the notable differences in invasive capacity between cancers of endodermal and mesodermal origins and cancers of ectodermal origin. Nevertheless, the available information indicates that cancer is an abnormal state of adult human cells in which developmental pathways are reactivated in inappropriate temporal and spatial contexts.
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Affiliation(s)
- Jaime Cofre
- Laboratório de Embriologia Molecular e Câncer, Universidade Federal de Santa Catarina, Sala 313b, 88040-900 Florianópolis, SC, Brazil
| | - Kay Saalfeld
- Laboratório de Filogenia Animal, Universidade Federal de Santa Catarina, Brazil
| | - Eliana Abdelhay
- Divisão de Laboratórios do CEMO, Instituto Nacional do Câncer, Rio de Janeiro, Brazil
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17
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Abstract
We present an overview of symmetry breaking in early mammalian development as a continuous process from compaction to specification of the body axes. While earlier studies have focused on individual symmetry-breaking events, recent advances enable us to explore progressive symmetry breaking during early mammalian development. Although we primarily discuss embryonic development of the mouse, as it is the best-studied mammalian model system to date, we also highlight the shared and distinct aspects between different mammalian species. Finally, we discuss how insights gained from studying mammalian development can be generalized in light of self-organization principles. With this review, we hope to highlight new perspectives in studying symmetry breaking and self-organization in multicellular systems.
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Affiliation(s)
- Hui Ting Zhang
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany;
| | - Takashi Hiiragi
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany;
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18
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Chen Q, Shi J, Tao Y, Zernicka-Goetz M. Tracing the origin of heterogeneity and symmetry breaking in the early mammalian embryo. Nat Commun 2018; 9:1819. [PMID: 29739935 PMCID: PMC5940674 DOI: 10.1038/s41467-018-04155-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 04/06/2018] [Indexed: 01/02/2023] Open
Abstract
A fundamental question in developmental and stem cell biology concerns the origin and nature of signals that initiate asymmetry leading to pattern formation and self-organization. Instead of having prominent pre-patterning determinants as present in model organisms (worms, sea urchin, frog), we propose that the mammalian embryo takes advantage of more subtle cues such as compartmentalized intracellular reactions that generate micro-scale inhomogeneity, which is gradually amplified over several cellular generations to drive pattern formation while keeping developmental plasticity. It is therefore possible that by making use of compartmentalized information followed by its amplification, mammalian embryos would follow general principle of development found in other organisms in which the spatial cue is more robustly presented.
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Affiliation(s)
- Qi Chen
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Junchao Shi
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, 89557, USA
| | - Yi Tao
- Center for Computational and Evolutionary Biology, Institute of Zoology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Magdalena Zernicka-Goetz
- Mammalian Development and Stem Cell Group, Department of Physiology, Development & Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
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19
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Southern HM, Berger MA, Young PG, Snook RR. Sperm morphology and the evolution of intracellular sperm-egg interactions. Ecol Evol 2018; 8:5047-5058. [PMID: 29876080 PMCID: PMC5980432 DOI: 10.1002/ece3.4027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/16/2018] [Accepted: 02/26/2018] [Indexed: 01/06/2023] Open
Abstract
Sperm morphology is incredibly diverse, even among closely related species, yet the coevolution between males and females of fertilization recognition systems is necessary for successful karyogamy (male and female pronuclear fusion). In most species, the entire sperm enters the egg during fertilization so sperm morphological diversity may impact the intracellular sperm-egg interactions necessary for karyogamy. We quantified morphological variation of sperm inside eggs prior to and following karyogamy in several species of Drosophila to understand whether evolution of sperm morphology could influence intracellular sperm-egg interactions (ISEIs). We measured seven parameters that describe ISEIs among species to determine whether these parameters varied both within a species across development and across species at the same developmental stage. We used heterospecific crosses to test the relative role of male origin, female origin, and interaction between the male and female in determining ISEIs. We found that sperm shape changed within a species as development proceeded and, at particular development stages, species varied in some ISEIs. Parental origin had an effect on some ISEIs, with a general trend for a stronger female effect. Overall, our findings identify conserved and variable ISEIs among species and demonstrate the potential to contribute understanding to gamete evolution and development.
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Affiliation(s)
- Helen M. Southern
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | | | - Philippe G. Young
- College of Engineering, Mathematics, and Physical SciencesUniversity of ExeterExeterUK
| | - Rhonda R. Snook
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
- Department of ZoologyStockholm UniversityStockholmSweden
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20
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Pijuan-Sala B, Guibentif C, Göttgens B. Single-cell transcriptional profiling: a window into embryonic cell-type specification. Nat Rev Mol Cell Biol 2018; 19:399-412. [DOI: 10.1038/s41580-018-0002-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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21
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Abstract
Marsupials and monotremes differ from eutherian mammals in many features of their reproduction and development. Some features appear to be representative of transitional stages in evolution from therapsid reptiles to humans and mice, particularly with respect to the extraembryonic tissues that have undergone remarkable modifications to accommodate reduced egg size and quantity of yolk/deutoplasm, and increasing emphasis on viviparity and placentation. Trophoblast and hypoblast contribute the epithelial layers in most of the extraembryonic membranes and are the first two lineages to differentiate from the embryonic lineage. How they are specified varies greatly among mammals, perhaps largely due to heterochrony in the stage at which they must function. Differences probably also exist in the stage at which lineages are specified relative to the stage at which they fully commit to differentiation. The dogma of sequential commitment to trophoblast and hypoblast with progressive loss of potency may not be a fundamental feature of early mammalian development, but merely a recently acquired developmental pattern in eutherians, or at least mice.
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22
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The Role of Maternal-Effect Genes in Mammalian Development: Are Mammalian Embryos Really an Exception? Stem Cell Rev Rep 2017; 12:276-84. [PMID: 26892267 DOI: 10.1007/s12015-016-9648-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The essential contribution of multiple maternal factors to early mammalian development is rapidly altering the view that mammals have a unique pattern of development compared to other species. Currently, over 60 maternal-effect mutations have been described in mammalian systems, including critical determinants of pluripotency. This data, combined with the evidence for lineage bias and differential gene expression in early blastomeres, strongly suggests that mammalian development is to some extent mosaic from the four-cell stage onward.
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23
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Sperm-borne miR-449b influences cleavage, epigenetic reprogramming and apoptosis of SCNT embryos in bovine. Sci Rep 2017; 7:13403. [PMID: 29042680 PMCID: PMC5645405 DOI: 10.1038/s41598-017-13899-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/02/2017] [Indexed: 01/23/2023] Open
Abstract
Accumulating evidence indicates the absence of paternally derived miRNAs, piwiRNAs, and proteins may be one important factor contributing to developmental failure in somatic cell cloned embryos. In the present study, we found microRNA-449b (miR-449b) was highly expressed in sperm. Target gene predictions and experimental verification indicate that several embryonic development-related genes, including CDK6, c-MYC, HDAC1 and BCL-2, are targets of miR-449b. We therefore investigated the role of miR-449b using somatic cell nuclear transfer (SCNT) embryo model. Bovine fetal fibroblasts, expressing miR-449b through a doxycycline (dox) induced expression system were used as nuclear donor cells for SCNT. The results showed that miR-449b expression in SCNT embryos significantly enhanced the cleavage rate at 48 h after activation and the levels of H3K9 acetylation at the 2-cell to 8-cell stages, meanwhile, significantly decreased the apoptosis index of blastocysts. In addition, we verified miR-449b could regulate the expression levels of CDK6, c-MYC, HDAC1 and BCL-2. In conclusion, the present study shows that miR-449b expression improves the first cleavage division, epigenetic reprogramming and apoptotic status of bovine preimplantation cloned embryos.
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24
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Hosseini SM, Moulavi F, TanhaieVash N, Shams-Esfandabadi N, Nasr-Esfahani MH, Shirazi A. Evidence of Oocyte Polarity in Bovine; Implications for Intracytoplasmic Sperm Injection and Somatic Cell Nuclear Transfer. CELL JOURNAL 2017; 19:482-491. [PMID: 28836411 PMCID: PMC5570413 DOI: 10.22074/cellj.2017.4887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 09/19/2016] [Indexed: 12/03/2022]
Abstract
Objective We recently demonstrated spatial regionalization of maternal transcripts and
proteins within unfertilized ovine oocyte. Here, we investigated the likelihood of oocyte
polarity for the first time in bovine. Materials and Methods In this experimental study, in vitro matured bovine oocytes were
used for manual bisection [into oocyte halve that were near-to (HNS) and far-from (FS)
spindle] or trisection [into MII-spindle (S), the spindle-side half (NS), and the distal half
unassociated with the spindle (FS)]. Prepared pools of oocyte substructures were used
for comparative quantitative real-time polymerase chain reaction (RT-qPCR). To map the
possible preferential sperm entry point (SEP), the spatial relationship between SEP and
MII-spindle was measured 5 hours post-fertilization. Results The proportional amount of maternal mRNA in S oocyte fragment was estimated
to be 6 to 11-fold higher than NS and FS counterparts. The relative abundances
of Nanog, Oct4, Fgf4 and Tead4 were significantly higher in HNS oocyte fragment
compared t0 FS. The relative abundances of Ctnb, Carm1, Rex1, Sox2 and Cdx2 were
comparable between HNS and NS oocyte fragments. FS oocyte fragment possessed significantly
higher transcripts of Gata4 compared to HNS. The distribution of certain transcripts
related to pluripotency and lineage commitment were different depending upon the
region of the oocyte; either enriched at S (Tead4, Nanog, Ctnb and Sox2), NS (Oct4), or
FS (Gata6). The SEP in almost (90%) fertilized oocytes was located in MII-hemisphere. Conclusion The observation of spatial restriction of mRNAs and SEP within MII-oocyte
may indicate that the principal forces of oocyte polarity are evolutionary conserved. This
may in turn highlight the need for refinements in the methodology of intracytoplasmic
sperm injection (where a sperm is injected far from the MII-spindle) and somatic cell nuclear
transfer (where a major amount of regulative mRNAs that are associated with MIIspindle
is removed during enucleation).
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Affiliation(s)
- Seyed Morteza Hosseini
- Research Institute of Animal Embryo Technology, Shahrekord University, Shahrekord, Iran.,Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Fariba Moulavi
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Nima TanhaieVash
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | | | - Mohammad Hossein Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.
| | - Abolfazl Shirazi
- Research Institute of Animal Embryo Technology, Shahrekord University, Shahrekord, Iran.,Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
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25
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Totipotency segregates between the sister blastomeres of two-cell stage mouse embryos. Sci Rep 2017; 7:8299. [PMID: 28811525 PMCID: PMC5557898 DOI: 10.1038/s41598-017-08266-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/06/2017] [Indexed: 11/09/2022] Open
Abstract
Following fertilization in mammals, it is generally accepted that totipotent cells are exclusive to the zygote and to each of the two blastomeres originating from the first mitotic division. This model of totipotency was inferred from a minority of cases in which blastomeres produced monozygotic twins in mice. Was this due to experimental limitation or biological constraint? Here we removed experimental obstacles and achieved reliable quantification of the prevalence of dual totipotency among mouse two-cell stage blastomeres. We separated the blastomeres of 1,252 two-cell embryos, preserving 1,210 of the pairs. Two classes of monozygotic twins became apparent at the blastocyst stage: 27% formed a functional epiblast in both members (concordant), and 73% did so in only one member of the pair (discordant) - a partition that proved insensitive to oocyte quality, sperm-entry point, culture environment and pattern of cleavage. In intact two-cell embryos, the ability of sister blastomeres to generate epiblast was also skewed. Class discovery clustering of the individual blastomeres' and blastocysts' transcriptomes points to an innate origin of concordance and discordance rather than developmental acquisition. Our data place constraints on the commonly accepted idea that totipotency is allocated equally between the two-cell stage blastomeres in mice.
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26
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Noli L, Ogilvie C, Khalaf Y, Ilic D. Potential of human twin embryos generated by embryo splitting in assisted reproduction and research. Hum Reprod Update 2017; 23:156-165. [PMID: 27852683 DOI: 10.1093/humupd/dmw041] [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: 05/25/2016] [Accepted: 11/02/2016] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Embryo splitting or twinning has been widely used in veterinary medicine over 20 years to generate monozygotic twins with desirable genetic characteristics. The first human embryo splitting, reported in 1993, triggered fierce ethical debate on human embryo cloning. Since Dolly the sheep was born in 1997, the international community has acknowledged the complexity of the moral arguments related to this research and has expressed concerns about the potential for reproductive cloning in humans. A number of countries have formulated bans either through laws, decrees or official statements. However, in general, these laws specifically define cloning as an embryo that is generated via nuclear transfer (NT) and do not mention embryo splitting. Only the UK includes under cloning both embryo splitting and NT in the same legislation. On the contrary, the Ethics Committee of the American Society for Reproductive Medicine does not have a major ethical objection to transferring two or more artificially created embryos with the same genome with the aim of producing a single pregnancy, stating that 'since embryo splitting has the potential to improve the efficacy of IVF treatments for infertility, research to investigate the technique is ethically acceptable'. OBJECTIVE AND RATIONALE Embryo splitting has been introduced successfully to the veterinary medicine several decades ago and today is a part of standard practice. We present here an overview of embryo splitting experiments in humans and non-human primates and discuss the potential of this technology in assisted reproduction and research. SEARCH METHODS A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies on embryo splitting in humans and non-human primates. 'Embryo splitting' and 'embryo twinning' were used as the keywords, alone or in combination with other search phrases relevant to the topics of biology of preimplantation embryos. OUTCOMES A very limited number of studies have been conducted in humans and non-human primates. The published material, especially the studies with human embryos, is controversial. Some reports suggest that twinning technology will find clinical use in reproductive medicine in the future, whereas others conclude the opposite that human twin embryos created in vitro are unsuitable not only for clinical, but also for research, purposes. WIDER IMPLICATIONS The blastomere biopsy technique of embryo splitting seems to be unsuitable for either clinical or research purposes; however, embryo bisection, a preferable method of cloning in veterinary medicine, has not yet been tested on human embryos.
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Affiliation(s)
- Laila Noli
- Division of Women's Health, Guy's Hospital, London SE1 9RT, UK.,Assisted Conception Unit, Guy's Hospital, London SE1 9RT, UK
| | - Caroline Ogilvie
- Genetics Laboratories, King's College London, Guy's Hospital, London SE1 9RT, UK
| | - Yacoub Khalaf
- Division of Women's Health, Guy's Hospital, London SE1 9RT, UK.,Assisted Conception Unit, Guy's Hospital, London SE1 9RT, UK
| | - Dusko Ilic
- Division of Women's Health, Guy's Hospital, London SE1 9RT, UK.,Assisted Conception Unit, Guy's Hospital, London SE1 9RT, UK
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27
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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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28
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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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Localization in Oogenesis of Maternal Regulators of Embryonic Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 953:173-207. [DOI: 10.1007/978-3-319-46095-6_5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Kimata Y, Higaki T, Kawashima T, Kurihara D, Sato Y, Yamada T, Hasezawa S, Berger F, Higashiyama T, Ueda M. Cytoskeleton dynamics control the first asymmetric cell division in Arabidopsis zygote. Proc Natl Acad Sci U S A 2016; 113:14157-14162. [PMID: 27911812 PMCID: PMC5150365 DOI: 10.1073/pnas.1613979113] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The asymmetric cell division of the zygote is the initial and crucial developmental step in most multicellular organisms. In flowering plants, whether zygote polarity is inherited from the preexisting organization in the egg cell or reestablished after fertilization has remained elusive. How dynamically the intracellular organization is generated during zygote polarization is also unknown. Here, we used a live-cell imaging system with Arabidopsis zygotes to visualize the dynamics of the major elements of the cytoskeleton, microtubules (MTs), and actin filaments (F-actins), during the entire process of zygote polarization. By combining image analysis and pharmacological experiments using specific inhibitors of the cytoskeleton, we found features related to zygote polarization. The preexisting alignment of MTs and F-actin in the egg cell is lost on fertilization. Then, MTs organize into a transverse ring defining the zygote subapical region and driving cell outgrowth in the apical direction. F-actin forms an apical cap and longitudinal arrays and is required to position the nucleus to the apical region of the zygote, setting the plane of the first asymmetrical division. Our findings show that, in flowering plants, the preexisting cytoskeletal patterns in the egg cell are lost on fertilization and that the zygote reorients the cytoskeletons to perform directional cell elongation and polar nuclear migration.
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Affiliation(s)
- Yusuke Kimata
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Takumi Higaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Tomokazu Kawashima
- Gregor Mendel Institute, Vienna Biocenter, Austrian Academy of Sciences, 1030 Vienna, Austria
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546
| | - Daisuke Kurihara
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
- Japan Science and Technology Agency, Exploratory Research for Advanced Technology Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Yoshikatsu Sato
- Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Tomomi Yamada
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
- Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Seiichiro Hasezawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Frederic Berger
- Gregor Mendel Institute, Vienna Biocenter, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Tetsuya Higashiyama
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
- Japan Science and Technology Agency, Exploratory Research for Advanced Technology Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
- Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Minako Ueda
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan;
- Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
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31
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Denker HW. Self-Organization of Stem Cell Colonies and of Early Mammalian Embryos: Recent Experiments Shed New Light on the Role of Autonomy vs. External Instructions in Basic Body Plan Development. Cells 2016; 5:E39. [PMID: 27792143 PMCID: PMC5187523 DOI: 10.3390/cells5040039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/08/2016] [Accepted: 10/12/2016] [Indexed: 12/23/2022] Open
Abstract
"Organoids", i.e., complex structures that can develop when pluripotent or multipotent stem cells are maintained in three-dimensional cultures, have become a new area of interest in stem cell research. Hopes have grown that when focussing experimentally on the mechanisms behind this type of in vitro morphogenesis, research aiming at tissue and organ replacements can be boosted. Processes leading to the formation of organoids in vitro are now often addressed as self-organization, a term referring to the formation of complex tissue architecture in groups of cells without depending on specific instruction provided by other cells or tissues. The present article focuses on recent reports using the term self-organization in the context of studies on embryogenesis, specifically addressing pattern formation processes in human blastocysts attaching in vitro, or in colonies of pluripotent stem cells ("gastruloids"). These morphogenetic processes are of particular interest because, during development in vivo, they lead to basic body plan formation and individuation. Since improved methodologies like those employed by the cited authors became available, early embryonic pattern formation/self-organization appears to evolve now as a research topic of its own. This review discusses concepts concerning the involved mechanisms, focussing on autonomy of basic body plan development vs. dependence on external signals, as possibly provided by implantation in the uterus, and it addresses biological differences between an early mammalian embryo, e.g., a morula, and a cluster of pluripotent stem cells. It is concluded that, apart from being of considerable biological interest, the described type of research needs to be contemplated carefully with regard to ethical implications when performed with human cells.
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Affiliation(s)
- Hans-Werner Denker
- Institut für Anatomie, Universität Duisburg-Essen, Universitätsklinikum, Hufelandstr. 55, 45122 Essen, Germany.
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32
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Chen Q, Yan W, Duan E. Epigenetic inheritance of acquired traits through sperm RNAs and sperm RNA modifications. Nat Rev Genet 2016; 17:733-743. [PMID: 27694809 DOI: 10.1038/nrg.2016.106] [Citation(s) in RCA: 306] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Once deemed heretical, emerging evidence now supports the notion that the inheritance of acquired characteristics can occur through ancestral exposures or experiences and that certain paternally acquired traits can be 'memorized' in the sperm as epigenetic information. The search for epigenetic factors in mammalian sperm that transmit acquired phenotypes has recently focused on RNAs and, more recently, RNA modifications. Here, we review insights that have been gained from studying sperm RNAs and RNA modifications, and their roles in influencing offspring phenotypes. We discuss the possible mechanisms by which sperm become acquisitive following environmental-somatic-germline interactions, and how they transmit paternally acquired phenotypes by shaping early embryonic development.
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Affiliation(s)
- Qi Chen
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada 89512, USA
| | - Wei Yan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, Nevada 89512, USA
| | - Enkui Duan
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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33
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34
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Lim CY, Knowles BB, Solter D, Messerschmidt DM. Epigenetic Control of Early Mouse Development. Curr Top Dev Biol 2016; 120:311-60. [PMID: 27475856 DOI: 10.1016/bs.ctdb.2016.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although the genes sequentially transcribed in the mammalian embryo prior to implantation have been identified, understanding of the molecular processes ensuring this transcription is still in development. The genomes of the sperm and egg are hypermethylated, hence transcriptionally silent. Their union, in the prepared environment of the egg, initiates their epigenetic genomic reprogramming into a totipotent zygote, in which the genome gradually becomes transcriptionally activated. During gametogenesis, sex-specific processes result in sperm and eggs with disparate epigenomes, both of which require drastic reprogramming to establish the totipotent genome of the zygote and the pluripotent inner cell mass of the blastocyst. Herein, we describe the factors, DNA and histone modifications, activation and repression of retrotransposons, and cytoplasmic localizations, known to influence the activation of the mammalian genome at the initiation of new life.
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Affiliation(s)
- C Y Lim
- Institute of Medical Biology, A*STAR, Singapore, Singapore
| | - B B Knowles
- Emerita, The Jackson Laboratory, Bar Harbor, ME, United States; Siriraj Center of Excellence for Stem Cell Research, Mahidol University, Bangkok, Thailand
| | - D Solter
- Siriraj Center of Excellence for Stem Cell Research, Mahidol University, Bangkok, Thailand; Emeritus, Max-Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
| | - D M Messerschmidt
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore.
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35
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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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36
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Zheng Z, Li H, Zhang Q, Yang L, Qi H. Unequal distribution of 16S mtrRNA at the 2-cell stage regulates cell lineage allocations in mouse embryos. Reproduction 2016; 151:351-67. [DOI: 10.1530/rep-15-0301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 01/13/2016] [Indexed: 12/30/2022]
Abstract
Cell lineage determination during early embryogenesis has profound effects on adult animal development. Pre-patterning of embryos, such as that of Drosophila and Caenorhabditis elegans, is driven by asymmetrically localized maternal or zygotic factors, including mRNA species and RNA binding proteins. However, it is not clear how mammalian early embryogenesis is regulated and what the early cell fate determinants are. Here we show that, in mouse, mitochondrial ribosomal RNAs (mtrRNAs) are differentially distributed between 2-cell sister blastomeres. This distribution pattern is not related to the overall quantity or activity of mitochondria which appears equal between 2-cell sister blastomeres. Like in lower species, 16S mtrRNA is found to localize in the cytoplasm outside of mitochondria in mouse 2-cell embryos. Alterations of 16S mtrRNA levels in one of the 2-cell sister blastomere via microinjection of either sense or anti-sense RNAs drive its progeny into different cell lineages in blastocyst. These results indicate that mtrRNAs are differentially distributed among embryonic cells at the beginning of embryogenesis in mouse and they are functionally involved in the regulation of cell lineage allocations in blastocyst, suggesting an underlying molecular mechanism that regulates pre-implantation embryogenesis in mouse.
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37
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Hosseini SM, Moulavi F, Tanhaie-Vash N, Asgari V, Ghanaei HR, Abedi-Dorche M, Jafarzadeh N, Gourabi H, Shahverdi AH, Dizaj AV, Shirazi A, Nasr-Esfahani MH. The Principal Forces of Oocyte Polarity Are Evolutionary Conserved but May Not Affect the Contribution of the First Two Blastomeres to the Blastocyst Development in Mammals. PLoS One 2016; 11:e0148382. [PMID: 27030988 PMCID: PMC4816511 DOI: 10.1371/journal.pone.0148382] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/18/2016] [Indexed: 11/26/2022] Open
Abstract
Oocyte polarity and embryonic patterning are well-established features of development in lower species. Whether a similar form of pre-patterning exists in mammals is currently under hot debate in mice. This study investigated this issue for the first time in ovine as a large mammal model. Microsurgical trisection of unfertilized MII-oocytes revealed that cortical cytoplasm around spindle (S) contained significant amounts of total maternal mRNAs and proteins compared to matched cytoplast hemispheres that were located either near (NS) or far (FS) -to-spindle. RT-qPCR provided striking examples of maternal mRNA localized to subcellular substructures S (NPM2, GMNN, H19, PCAF, DNMT3A, DNMT1, and STELLA), NS (SOX2, NANOG, POU5F1, and TET1), and FS (GCN) of MII oocyte. Immunoblotting revealed that specific maternal proteins DNMT3A and NANOG were asymmetrically enriched in MII-spindle-half of the oocytes. Topological analysis of sperm entry point (SEP) revealed that sperm preferentially entered via the MII-spindle-half of the oocytes. Even though, the topological position of first cleavage plane with regard to SEP was quite stochastic. Spatial comparison of lipid content revealed symmetrical distribution of lipids between 2-cell blastomeres. Lineage tracing using Dil, a fluorescent dye, revealed that while the progeny of leading blastomere of 2-cell embryos contributed to more cells in the developed blastocysts compared to lagging counterpart, the contributions of leading and lagging blastomeres to the embryonic-abembryonic parts of the developed blastocysts were almost unbiased. And finally, separated sister blastomeres of 2-cell embryos had an overall similar probability to arrest at any stage before the blastocyst (2-cell, 4-cell, 8-cell, and morula) or to achieve the blastocyst stage. It was concluded that the localization of maternal mRNAs and proteins at the spindle are evolutionarily conserved between mammals unfertilized ovine oocyte could be considered polar with respect to the spatial regionalization of maternal transcripts and proteins. Even though, the principal forces of this definitive oocyte polarity may not persist during embryonic cleavages.
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Affiliation(s)
- Sayyed-Morteza Hosseini
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Fariba Moulavi
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Nima Tanhaie-Vash
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Vajihe Asgari
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Hamid-Reza Ghanaei
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Maryam Abedi-Dorche
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Naser Jafarzadeh
- Department of Medical Physics, Tarbiat Modares University, Tehran, Iran
| | - Hossein Gourabi
- Department of Genetics at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, P.O. Box: 19395–4644, Tehran, Iran
| | - Abdol-Hossein Shahverdi
- Department of Embryology at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Medicine, ACECR, Tehran, Iran
| | - Ahmad Vosough Dizaj
- Department of Reproductive Imaging at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Abolfazl Shirazi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
- Research Institute of Animal Embryo Technology, Shahrekord University, Shahrekord, Iran
- * E-mail: (AS); (MHNE)
| | - Mohammad-Hossein Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
- * E-mail: (AS); (MHNE)
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38
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Boiani M, Cibelli JB. What we can learn from single-cell analysis in development. Mol Hum Reprod 2016; 22:160-71. [DOI: 10.1093/molehr/gaw014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Abstract
Whether or not early mammalian development results from preformation or epigenesis remains an unresolved issue. Evidence for or against either is weak, inconclusive, and often misinterpreted. Yet, one can parsimoniously conceptualize formation of the mouse blastocyst as a series of random, stochastic events stemming from initial and sequential small asymmetries in egg, zygote, and cleavage stages. Differential compartmentalized gene expression does not lead but follows the morphogenesis and cell fate allocation in the mammalian blastocyst.
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40
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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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41
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Noli L, Dajani Y, Capalbo A, Bvumbe J, Rienzi L, Ubaldi FM, Ogilvie C, Khalaf Y, Ilic D. Developmental clock compromises human twin model created by embryo splitting. Hum Reprod 2015; 30:2774-84. [PMID: 26489438 DOI: 10.1093/humrep/dev252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/15/2015] [Indexed: 12/26/2022] Open
Abstract
STUDY QUESTION Is the quality of the human embryos generated by twinning in vitro comparable to the quality of the embryos created by fertilization? SUMMARY ANSWER Our data suggest that the human twin embryos created in vitro are unsuitable not only for clinical use but also for research purposes. WHAT IS KNOWN ALREADY Pregnancy from in vitro generated monozygotic twins by embryo splitting or twinning leads to live birth of healthy animals. Similar strategies, however, have been less successful in primates. Recent reports suggest that the splitting of human embryos might result in viable, morphologically adequate blastocysts, although the qualitative analyses of the embryos created in such a way have been very limited. STUDY DESIGN, SIZE, DURATION This study was a comparative analysis of embryos generated by twinning in vitro and the embryos created by in vitro fertilization. PARTICIPANTS/MATERIALS, SETTING, METHODS We analysed morphokinetics and developmental competence of 176 twin embryos created by splitting of 88 human embryos from either early (2-5 blastomeres, n = 43) or late (6-10 blastomeres, n = 45) cleavage stages. We compared the data with morphometrics of embryos created by in vitro fertilization and resulting in pregnancy and live birth upon single blastocyst transfer (n = 42). MAIN RESULTS AND THE ROLE OF CHANCE The morphokinetic data suggested that the human preimplantation development is subjected to a strict temporal control. Due to a 'developmental clock', the size of twin embryos was proportionate to the number of cells used for their creation. Furthermore, the first fate decision was somewhat delayed; the inner cell mass (ICM) became distinguishable later in the twin than in the normal blastocysts obtained through fertilization. If an ICM was present at all, it was small and of poor quality. The majority of the cells in the twin embryos expressed ICM and trophectoderm markers simultaneously. LIMITATIONS, REASONS FOR CAUTION We created monozygotic twins by blastomere separation from cleavage stage embryos. Embryo twinning by blastocyst bisection may circumvent limitations set by the developmental clock. WIDER IMPLICATIONS OF THE FINDINGS Taken together, our data suggest that the human twin embryos created in vitro are unsuitable not only for clinical use but also for research purposes.
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Affiliation(s)
- Laila Noli
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London and Assisted Conception Unit, Guys' Hospital, London SE1 9RT, UK
| | - Yaser Dajani
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London and Assisted Conception Unit, Guys' Hospital, London SE1 9RT, UK
| | - Antonio Capalbo
- GENERA, Centre for Reproductive Medicine, Clinica Valle Giulia, Rome 00197, Italy GENETYX, Molecular Genetics Laboratory, Via Fermi 1, Marostica 36063, Italy
| | - Jean Bvumbe
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London and Assisted Conception Unit, Guys' Hospital, London SE1 9RT, UK
| | - Laura Rienzi
- GENERA, Centre for Reproductive Medicine, Clinica Valle Giulia, Rome 00197, Italy GENETYX, Molecular Genetics Laboratory, Via Fermi 1, Marostica 36063, Italy
| | - Filippo Maria Ubaldi
- GENERA, Centre for Reproductive Medicine, Clinica Valle Giulia, Rome 00197, Italy GENETYX, Molecular Genetics Laboratory, Via Fermi 1, Marostica 36063, Italy
| | | | - Yacoub Khalaf
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London and Assisted Conception Unit, Guys' Hospital, London SE1 9RT, UK
| | - Dusko Ilic
- Division of Women's Health, Faculty of Life Sciences and Medicine, King's College London and Assisted Conception Unit, Guys' Hospital, London SE1 9RT, UK
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42
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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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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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44
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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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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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Stensen MH, Tanbo TG, Storeng R, Åbyholm T, Fedorcsak P. Fragmentation of human cleavage-stage embryos is related to the progression through meiotic and mitotic cell cycles. Fertil Steril 2014; 103:374-81.e4. [PMID: 25467039 DOI: 10.1016/j.fertnstert.2014.10.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/16/2014] [Accepted: 10/20/2014] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To study whether fragmentation of human embryos is related to the progression through meiotic and mitotic cell cycles. DESIGN This report consists of two observational studies. SETTING Not applicable. PATIENT(S) A total of 1,943 oocytes from 297 patients and 372 embryos from 100 patients were imaged in the Polscope instrument and monitored in the Embryoscope, respectively. INTERVENTION(S) Completion of the first meiotic division was determined by visualization of the meiotic metaphase II spindle in human oocytes, and the duration of the first three mitotic cell cycles was determined with time-lapse microscopy. The percentage of embryo fragmentation was recorded 42-45 hours after insemination. MAIN OUTCOME MEASURE(S) Appearance of the meiotic spindle; durations of the first, second, and third mitoses. RESULT(S) Human embryos with a low degree of fragmentation (<10%) at 42-45 hours after insemination originated from oocytes with an early appearance of the meiotic spindle (mean 35.5 hours after hCG injection), early first mitosis (28.2 hours after insemination), late start of the second mitosis (38.0 hours after insemination), and a shorter duration of the third mitosis (1.1 hours). Highly fragmented embryos (>50% fragmentation) originated from oocytes with a late-appearing meiotic spindle (36.5 hours after hCG injection), delayed initiation of the first mitosis (29.8 hours after insemination), early start of the second mitosis (36.4 hours after insemination), and a longer duration of the third mitotic cell cycle (4.1 hours). CONCLUSION(S) The observed associations suggest that the process of fragmentation of in vitro-derived embryos was related to the progress of the meiotic and the mitotic cell cycles.
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Affiliation(s)
- Mette Haug Stensen
- Norwegian National Advisory Unit on Women's Health, Women and Children's Division, Oslo University Hospital Rikshospitalet, Oslo, Norway.
| | - Tom Gunnar Tanbo
- Section of Reproductive Medicine, Department of Gynecology, Oslo University Hospital Rikshospitalet, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Ritsa Storeng
- Norwegian National Advisory Unit on Women's Health, Women and Children's Division, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Thomas Åbyholm
- Department of Obstetrics, Women and Children's Division, Oslo University Hospital Rikshospitalet, Oslo, Norway
| | - Peter Fedorcsak
- Section of Reproductive Medicine, Department of Gynecology, Oslo University Hospital Rikshospitalet, Oslo, Norway
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Bozorgmehr JEH. The role of self-organization in developmental evolution. Theory Biosci 2014; 133:145-63. [PMID: 24737046 DOI: 10.1007/s12064-014-0200-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 03/06/2014] [Indexed: 01/09/2023]
Abstract
In developmental and evolutionary biology, particular emphasis has been given to the relationship between transcription factors and the cognate cis-regulatory elements of their target genes. These constitute the gene regulatory networks that control expression and are assumed to causally determine the formation of structures and body plans. Comparative analysis has, however, established a broad sequence homology among species that nonetheless display quite different anatomies. Transgenic experiments have also confirmed that many developmentally important elements are, in fact, functionally interchangeable. Although dependent upon the appropriate degree of gene expression, the actual construction of specific structures appears not directly linked to the functions of gene products alone. Instead, the self-formation of complex patterns, due in large part to epigenetic and non-genetic determinants, remains a persisting theme in the study of ontogeny and regenerative medicine. Recent evidence indeed points to the existence of a self-organizing process, operating through a set of intrinsic rules and forces, which imposes coordination and a holistic order upon cells and tissue. This has been repeatedly demonstrated in experiments on regeneration as well as in the autonomous formation of structures in vitro. The process cannot be wholly attributed to the functional outcome of protein-protein interactions or to concentration gradients of diffusible chemicals. This phenomenon is examined here along with some of the methodological and theoretical approaches that are now used in understanding the causal basis for self-organization in development and its evolution.
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Ajduk A, Zernicka-Goetz M. Quality control of embryo development. Mol Aspects Med 2013; 34:903-18. [DOI: 10.1016/j.mam.2013.03.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 03/05/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
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Arias AM, Nichols J, Schröter C. A molecular basis for developmental plasticity in early mammalian embryos. Development 2013; 140:3499-510. [DOI: 10.1242/dev.091959] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Early mammalian embryos exhibit remarkable plasticity, as highlighted by the ability of separated early blastomeres to produce a whole organism. Recent work in the mouse implicates a network of transcription factors in governing the establishment of the primary embryonic lineages. A combination of genetics and embryology has uncovered the organisation and function of the components of this network, revealing a gradual resolution from ubiquitous to lineage-specific expression through a combination of defined regulatory relationships, spatially organised signalling, and biases from mechanical inputs. Here, we summarise this information, link it to classical embryology and propose a molecular framework for the establishment and regulation of developmental plasticity.
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Affiliation(s)
| | - Jennifer Nichols
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 3EH, UK
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Abstract
Cells of early mouse embryo were considered for a long time to acquire cell fate at random. Recent analyses argue against this simple model.
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