1
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Sonnen KF. Setting the stage for embryo segmentation. Cell Stem Cell 2024; 31:1097-1098. [PMID: 39094539 DOI: 10.1016/j.stem.2024.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 08/04/2024]
Abstract
Morphogen gradients are critical regulators of embryonic development. In this issue, Liu et al.1 introduce a microfluidic system that externally applies morphogen gradients to an in vitro model of human embryo segmentation. It enables the investigation of signaling gradients during this developmental process at unprecedented levels of precision.
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Affiliation(s)
- Katharina F Sonnen
- Hubrecht Institute-KNAW, University Medical Center Utrecht, Uppsalalaan 8 3584 CT Utrecht, the Netherlands.
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2
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Miao Y, Pourquié O. Cellular and molecular control of vertebrate somitogenesis. Nat Rev Mol Cell Biol 2024; 25:517-533. [PMID: 38418851 DOI: 10.1038/s41580-024-00709-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 03/02/2024]
Abstract
Segmentation is a fundamental feature of the vertebrate body plan. This metameric organization is first implemented by somitogenesis in the early embryo, when paired epithelial blocks called somites are rhythmically formed to flank the neural tube. Recent advances in in vitro models have offered new opportunities to elucidate the mechanisms that underlie somitogenesis. Notably, models derived from human pluripotent stem cells introduced an efficient proxy for studying this process during human development. In this Review, we summarize the current understanding of somitogenesis gained from both in vivo studies and in vitro studies. We deconstruct the spatiotemporal dynamics of somitogenesis into four distinct modules: dynamic events in the presomitic mesoderm, segmental determination, somite anteroposterior polarity patterning, and epithelial morphogenesis. We first focus on the segmentation clock, as well as signalling and metabolic gradients along the tissue, before discussing the clock and wavefront and other models that account for segmental determination. We then detail the molecular and cellular mechanisms of anteroposterior polarity patterning and somite epithelialization.
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Affiliation(s)
- Yuchuan Miao
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
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3
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Maia-Fernandes AC, Martins-Jesus A, Borralho-Martins N, Pais-de-Azevedo T, Magno R, Duarte I, Andrade RP. Spatio-temporal dynamics of early somite segmentation in the chicken embryo. PLoS One 2024; 19:e0297853. [PMID: 38635504 PMCID: PMC11025740 DOI: 10.1371/journal.pone.0297853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/10/2024] [Indexed: 04/20/2024] Open
Abstract
During vertebrate embryo development, the body is progressively segmented along the anterior-posterior (A-P) axis early in development. The rate of somite formation is controlled by the somitogenesis embryo clock (EC), which was first described as gene expression oscillations of hairy1 (hes4) in the presomitic mesoderm of chick embryos with 15-20 somites. Here, the EC displays the same periodicity as somite formation, 90 min, whereas the posterior-most somites (44-52) only arise every 150 minutes, matched by a corresponding slower pace of the EC. Evidence suggests that the rostral-most somites are formed faster, however, their periodicity and the EC expression dynamics in these early stages are unknown. In this study, we used time-lapse imaging of chicken embryos from primitive streak to somitogenesis stages with high temporal resolution (3-minute intervals). We measured the length between the anterior-most and the last formed somitic clefts in each captured frame and developed a simple algorithm to automatically infer both the length and time of formation of each somite. We found that the occipital somites (up to somite 5) form at an average rate of 75 minutes, while somites 6 onwards are formed approximately every 90 minutes. We also assessed the expression dynamics of hairy1 using half-embryo explants cultured for different periods of time. This showed that EC hairy1 expression is highly dynamic prior to somitogenesis and assumes a clear oscillatory behaviour as the first somites are formed. Importantly, using ex ovo culture and live-imaging techniques, we showed that the hairy1 expression pattern recapitulates with the formation of each new pair of somites, indicating that somite segmentation is coupled with EC oscillations since the onset of somitogenesis.
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Affiliation(s)
- Ana Cristina Maia-Fernandes
- ABC-RI, Algarve Biomedical Center Research Institute, Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Faro, Portugal
| | - Ana Martins-Jesus
- ABC-RI, Algarve Biomedical Center Research Institute, Faro, Portugal
| | - Nísia Borralho-Martins
- ABC-RI, Algarve Biomedical Center Research Institute, Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Faro, Portugal
| | - Tomás Pais-de-Azevedo
- ABC-RI, Algarve Biomedical Center Research Institute, Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Faro, Portugal
| | | | - Isabel Duarte
- Pattern Institute, Faro, Portugal
- CINTESIS@RISE, Universidade do Algarve, Faro, Portugal
| | - Raquel P. Andrade
- ABC-RI, Algarve Biomedical Center Research Institute, Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas (FMCB), Universidade do Algarve, Faro, Portugal
- Champalimaud Research Program, Champalimaud Center for the Unknown, Lisbon, Portugal
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4
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Abstract
In avian and mammalian embryos the "organizer" property associated with neural induction of competent ectoderm into a neural plate and its subsequent patterning into rostro-caudal domains resides at the tip of the primitive streak before neurulation begins, and before a morphological Hensen's node is discernible. The same region and its later derivatives (like the notochord) also have the ability to "dorsalize" the adjacent mesoderm, for example by converting lateral plate mesoderm into paraxial (pre-somitic) mesoderm. Both neural induction and dorsalization of the mesoderm involve inhibition of BMP, and the former also requires other signals. This review surveys the key experiments done to elucidate the functions of the organizer and the mechanisms of neural induction in amniotes. We conclude that the mechanisms of neural induction in amniotes and anamniotes are likely to be largely the same; apparent differences are likely to be due to differences in experimental approaches dictated by embryo topology and other practical constraints. We also discuss the relationships between "neural induction" assessed by grafts of the organizer and normal neural plate development, as well as how neural induction relates to the generation of neuronal cells from embryonic and other stem cells in vitro.
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Affiliation(s)
- Claudio D Stern
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.
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5
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McDaniel C, Simsek MF, Chandel AS, Özbudak EM. Spatiotemporal control of pattern formation during somitogenesis. SCIENCE ADVANCES 2024; 10:eadk8937. [PMID: 38277458 PMCID: PMC10816718 DOI: 10.1126/sciadv.adk8937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 12/27/2023] [Indexed: 01/28/2024]
Abstract
Spatiotemporal patterns widely occur in biological, chemical, and physical systems. Particularly, embryonic development displays a diverse gamut of repetitive patterns established in many tissues and organs. Branching treelike structures in lungs, kidneys, livers, pancreases, and mammary glands as well as digits and bones in appendages, teeth, and palates are just a few examples. A fascinating instance of repetitive patterning is the sequential segmentation of the primary body axis, which is conserved in all vertebrates and many arthropods and annelids. In these species, the body axis elongates at the posterior end of the embryo containing an unsegmented tissue. Meanwhile, segments sequentially bud off from the anterior end of the unsegmented tissue, laying down an exquisite repetitive pattern and creating a segmented body plan. In vertebrates, the paraxial mesoderm is sequentially divided into somites. In this review, we will discuss the most prominent models, the most puzzling experimental data, and outstanding questions in vertebrate somite segmentation.
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Affiliation(s)
- Cassandra McDaniel
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Systems Biology and Physiology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - M. Fethullah Simsek
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Angad Singh Chandel
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Systems Biology and Physiology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Ertuğrul M. Özbudak
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
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6
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Busby L, Serrano Nájera G, Steventon BJ. Intrinsic and extrinsic cues time somite progenitor contribution to the vertebrate primary body axis. eLife 2024; 13:e90499. [PMID: 38193440 PMCID: PMC10834026 DOI: 10.7554/elife.90499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 01/08/2024] [Indexed: 01/10/2024] Open
Abstract
During embryonic development, the timing of events at the cellular level must be coordinated across multiple length scales to ensure the formation of a well-proportioned body plan. This is clear during somitogenesis, where progenitors must be allocated to the axis over time whilst maintaining a progenitor population for continued elaboration of the body plan. However, the relative importance of intrinsic and extrinsic signals in timing progenitor addition at the single-cell level is not yet understood. Heterochronic grafts from older to younger embryos have suggested a level of intrinsic timing whereby later staged cells contribute to more posterior portions of the axis. To determine the precise step at which cells are delayed, we performed single-cell transcriptomic analysis on heterochronic grafts of somite progenitors in the chicken embryo. This revealed a previously undescribed cell state within which heterochronic grafted cells are stalled. The delayed exit of older cells from this state correlates with expression of posterior Hox genes. Using grafting and explant culture, we find that both Hox gene expression and the migratory capabilities of progenitor populations are intrinsically regulated at the population level. However, by grafting varied sizes of tissue, we find that small heterochronic grafts disperse more readily and contribute to more anterior portions of the body axis while still maintaining Hox gene expression. This enhanced dispersion is not replicated in explant culture, suggesting that it is a consequence of interaction between host and donor tissue and thus extrinsic to the donor tissue. Therefore, we demonstrate that the timing of cell dispersion and resulting axis contribution is impacted by a combination of both intrinsic and extrinsic cues.
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Affiliation(s)
- Lara Busby
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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7
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Lozovska A, Korovesi AG, Duarte P, Casaca A, Assunção T, Mallo M. The control of transitions along the main body axis. Curr Top Dev Biol 2023; 159:272-308. [PMID: 38729678 DOI: 10.1016/bs.ctdb.2023.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Although vertebrates display a large variety of forms and sizes, the mechanisms controlling the layout of the basic body plan are substantially conserved throughout the clade. Following gastrulation, head, trunk, and tail are sequentially generated through the continuous addition of tissue at the caudal embryonic end. Development of each of these major embryonic regions is regulated by a distinct genetic network. The transitions from head-to-trunk and from trunk-to-tail development thus involve major changes in regulatory mechanisms, requiring proper coordination to guarantee smooth progression of embryonic development. In this review, we will discuss the key cellular and embryological events associated with those transitions giving particular attention to their regulation, aiming to provide a cohesive outlook of this important component of vertebrate development.
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Affiliation(s)
| | | | - Patricia Duarte
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, Oeiras, Portugal
| | - Ana Casaca
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, Oeiras, Portugal
| | - Tereza Assunção
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, Oeiras, Portugal
| | - Moises Mallo
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, Oeiras, Portugal.
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8
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Masak G, Davidson LA. Constructing the pharyngula: Connecting the primary axial tissues of the head with the posterior axial tissues of the tail. Cells Dev 2023; 176:203866. [PMID: 37394035 PMCID: PMC10756936 DOI: 10.1016/j.cdev.2023.203866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/04/2023] [Accepted: 06/29/2023] [Indexed: 07/04/2023]
Abstract
The pharyngula stage of vertebrate development is characterized by stereotypical arrangement of ectoderm, mesoderm, and neural tissues from the anterior spinal cord to the posterior, yet unformed tail. While early embryologists over-emphasized the similarity between vertebrate embryos at the pharyngula stage, there is clearly a common architecture upon which subsequent developmental programs generate diverse cranial structures and epithelial appendages such as fins, limbs, gills, and tails. The pharyngula stage is preceded by two morphogenetic events: gastrulation and neurulation, which establish common shared structures despite the occurrence of cellular processes that are distinct to each of the species. Even along the body axis of a singular organism, structures with seemingly uniform phenotypic characteristics at the pharyngula stage have been established by different processes. We focus our review on the processes underlying integration of posterior axial tissue formation with the primary axial tissues that creates the structures laid out in the pharyngula. Single cell sequencing and novel gene targeting technologies have provided us with new insights into the differences between the processes that form the anterior and posterior axis, but it is still unclear how these processes are integrated to create a seamless body. We suggest that the primary and posterior axial tissues in vertebrates form through distinct mechanisms and that the transition between these mechanisms occur at different locations along the anterior-posterior axis. Filling gaps that remain in our understanding of this transition could resolve ongoing problems in organoid culture and regeneration.
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Affiliation(s)
- Geneva Masak
- Integrative Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Lance A Davidson
- Integrative Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Developmental Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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9
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Zhu K, Spaink HP, Durston AJ. Patterning of the Vertebrate Head in Time and Space by BMP Signaling. J Dev Biol 2023; 11:31. [PMID: 37489332 PMCID: PMC10366882 DOI: 10.3390/jdb11030031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/26/2023] Open
Abstract
How head patterning is regulated in vertebrates is yet to be understood. In this study, we show that frog embryos injected with Noggin at different blastula and gastrula stages had their head development sequentially arrested at different positions. When timed BMP inhibition was applied to BMP-overexpressing embryos, the expression of five genes: xcg-1 (a marker of the cement gland, which is the front-most structure in the frog embryo), six3 (a forebrain marker), otx2 (a forebrain and mid-brain marker), gbx2 (an anterior hindbrain marker), and hoxd1 (a posterior hindbrain marker) were sequentially fixed. These results suggest that the vertebrate head is patterned from anterior to posterior in a progressive fashion and may involve timed actions of the BMP signaling.
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Affiliation(s)
- Kongju Zhu
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
- Department of Pathology, Brigham and Women's Hospital, 60 Fenwood Road, Boston, MA 02115, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Division of Genetics and Genomics, Boston Children's Hospital, Center for Life Sciences, Blackfan Circle, Boston, MA 02115, USA
| | - Herman P Spaink
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
| | - Antony J Durston
- Institute of Biology, Leiden University, Sylviusweg 72, 2333BE Leiden, The Netherlands
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10
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Miao Y, Djeffal Y, De Simone A, Zhu K, Lee JG, Lu Z, Silberfeld A, Rao J, Tarazona OA, Mongera A, Rigoni P, Diaz-Cuadros M, Song LMS, Di Talia S, Pourquié O. Reconstruction and deconstruction of human somitogenesis in vitro. Nature 2023; 614:500-508. [PMID: 36543321 PMCID: PMC10018515 DOI: 10.1038/s41586-022-05655-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
The vertebrate body displays a segmental organization that is most conspicuous in the periodic organization of the vertebral column and peripheral nerves. This metameric organization is first implemented when somites, which contain the precursors of skeletal muscles and vertebrae, are rhythmically generated from the presomitic mesoderm. Somites then become subdivided into anterior and posterior compartments that are essential for vertebral formation and segmental patterning of the peripheral nervous system1-4. How this key somitic subdivision is established remains poorly understood. Here we introduce three-dimensional culture systems of human pluripotent stem cells called somitoids and segmentoids, which recapitulate the formation of somite-like structures with anteroposterior identity. We identify a key function of the segmentation clock in converting temporal rhythmicity into the spatial regularity of anterior and posterior somitic compartments. We show that an initial 'salt and pepper' expression of the segmentation gene MESP2 in the newly formed segment is transformed into compartments of anterior and posterior identity through an active cell-sorting mechanism. Our research demonstrates that the major patterning modules that are involved in somitogenesis, including the clock and wavefront, anteroposterior polarity patterning and somite epithelialization, can be dissociated and operate independently in our in vitro systems. Together, we define a framework for the symmetry-breaking process that initiates somite polarity patterning. Our work provides a platform for decoding general principles of somitogenesis and advancing knowledge of human development.
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Affiliation(s)
- Yuchuan Miao
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Yannis Djeffal
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | | | - Kongju Zhu
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Jong Gwan Lee
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Ziqi Lu
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA
| | - Andrew Silberfeld
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Jyoti Rao
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Oscar A Tarazona
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Alessandro Mongera
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Pietro Rigoni
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Margarete Diaz-Cuadros
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Laura Min Sook Song
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
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11
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Periodic inhibition of Erk activity drives sequential somite segmentation. Nature 2023; 613:153-159. [PMID: 36517597 PMCID: PMC9846577 DOI: 10.1038/s41586-022-05527-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/04/2022] [Indexed: 12/23/2022]
Abstract
Sequential segmentation creates modular body plans of diverse metazoan embryos1-4. Somitogenesis establishes the segmental pattern of the vertebrate body axis. A molecular segmentation clock in the presomitic mesoderm sets the pace of somite formation4. However, how cells are primed to form a segment boundary at a specific location remains unclear. Here we developed precise reporters for the clock and double-phosphorylated Erk (ppErk) gradient in zebrafish. We show that the Her1-Her7 oscillator drives segmental commitment by periodically lowering ppErk, therefore projecting its oscillation onto the ppErk gradient. Pulsatile inhibition of the ppErk gradient can fully substitute for the role of the clock, and kinematic clock waves are dispensable for sequential segmentation. The clock functions upstream of ppErk, which in turn enables neighbouring cells to discretely establish somite boundaries in zebrafish5. Molecularly divergent clocks and morphogen gradients were identified in sequentially segmenting species3,4,6-8. Our findings imply that versatile clocks may establish sequential segmentation in diverse species provided that they inhibit gradients.
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12
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Piatkowska AM, Adhikari K, Moverley AA, Turmaine M, Glazier JA, Plachta N, Evans SE, Stern CD. Sequential changes in cellular properties accompanying amniote somite formation. J Anat 2022; 242:417-435. [PMID: 36423208 PMCID: PMC9919497 DOI: 10.1111/joa.13791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/30/2022] [Accepted: 10/28/2022] [Indexed: 11/26/2022] Open
Abstract
Somites are transient structures derived from the pre-somitic mesoderm (PSM), involving mesenchyme-to-epithelial transition (MET) where the cells change their shape and polarize. Using Scanning electron microscopy (SEM), immunocytochemistry and confocal microscopy, we study the progression of these events along the tail-to-head axis of the embryo, which mirrors the progression of somitogenesis (younger cells located more caudally). SEM revealed that PSM epithelialization is a gradual process, which begins much earlier than previously thought, starting with the dorsalmost cells, then the medial ones, and then, simultaneously, the ventral and lateral cells, before a somite fully separates from the PSM. The core (internal) cells of the PSM and somites never epithelialize, which suggests that the core cells could be 'trapped' within the somitocoele after cells at the surfaces of the PSM undergo MET. Three-dimensional imaging of the distribution of the cell polarity markers PKCζ, PAR3, ZO1, the Golgi marker GM130 and the apical marker N-cadherin reveal that the pattern of polarization is distinctive for each marker and for each surface of the PSM, but the order of these events is not the same as the progression of cell elongation. These observations challenge some assumptions underlying existing models of somite formation.
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Affiliation(s)
- Agnieszka M. Piatkowska
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK
| | - Kaustubh Adhikari
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK,Present address:
The Open UniversityMilton KeynesUK
| | - Adam A. Moverley
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK
| | - Mark Turmaine
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK
| | - James A. Glazier
- Department of Intelligent Systems EngineeringBiocomplexity InstituteBloomingtonIndianaUSA
| | - Nicolas Plachta
- Department of Cell and Developmental Biology, 9‐123 Smilow Center for Translational Research, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Susan E. Evans
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK
| | - Claudio D. Stern
- Department of Cell & Developmental BiologyUniversity College London, Gower Street (Anatomy Building)LondonUK
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13
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Naznin RA, Haq MA, Sumi SA, Ahmad R, Haque M. A Semi-quantitative Evaluation of Out-to-Out Agenesis of Posterior Wall in a Dry Human Sacrum in Bangladesh. Cureus 2022; 14:e31163. [DOI: 10.7759/cureus.31163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2022] [Indexed: 11/07/2022] Open
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14
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Bao M, Cornwall-Scoones J, Zernicka-Goetz M. Stem-cell-based human and mouse embryo models. Curr Opin Genet Dev 2022; 76:101970. [PMID: 35988317 PMCID: PMC10309046 DOI: 10.1016/j.gde.2022.101970] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/17/2022] [Accepted: 07/19/2022] [Indexed: 11/26/2022]
Abstract
Synthetic embryology aims to develop embryo-like structures from stem cells to provide new insight into early stages of mammalian development. Recent advances in synthetic embryology have highlighted the remarkable capacity of stem cells to self-organize under certain biochemical or biophysical stimulations, generating structures that recapitulate the fate and form of early mouse/human embryos, in which symmetry breaking, pattern formation, or proper morphogenesis can be observed spontaneously. Here we review recent progress on the design principles for different types of embryoids and discuss the impact of different biochemical and biophysical factors on the process of stem-cell self-organization. We also offer our thoughts about the principal future challenges.
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Affiliation(s)
- Min Bao
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 E. California Boulevard, Pasadena, CA 91125, USA; Mammalian Embryo and Stem Cell Group, Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK. https://twitter.com/@Min_Bao_
| | - Jake Cornwall-Scoones
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 E. California Boulevard, Pasadena, CA 91125, USA; The Francis Crick Institute, London NW1 1AT, UK. https://twitter.com/@jake_cs_
| | - Magdalena Zernicka-Goetz
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 E. California Boulevard, Pasadena, CA 91125, USA; Mammalian Embryo and Stem Cell Group, Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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15
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Solovieva T, Wilson V, Stern CD. A niche for axial stem cells - A cellular perspective in amniotes. Dev Biol 2022; 490:13-21. [PMID: 35779606 PMCID: PMC10497457 DOI: 10.1016/j.ydbio.2022.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 05/19/2022] [Accepted: 06/25/2022] [Indexed: 11/24/2022]
Abstract
The head-tail axis in birds and mammals develops from a growth zone in the tail-end, which contains the node. This growth zone then forms the tailbud. Labelling experiments have shown that while many cells leave the node and tailbud to contribute to axial (notochord, floorplate) and paraxial (somite) structures, some cells remain resident in the node and tailbud. Could these cells be resident axial stem cells? If so, do the node and tailbud represent an instructive stem cell niche that specifies and maintains these stem cells? Serial transplantation and single cell labelling studies support the existence of self-renewing stem cells and heterotopic transplantations suggest that the node can instruct such self-renewing behaviour. However, only single cell manipulations can reveal whether self-renewing behaviour occurs at the level of a cell population (asymmetric or symmetric cell divisions) or at the level of single cells (asymmetric divisions only). We combine data on resident cells in the node and tailbud and review it in the context of axial development in chick and mouse, summarising our current understanding of axial stem cells and their niche and highlighting future directions of interest.
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Affiliation(s)
- Tatiana Solovieva
- Department of Cell and Developmental Biology, University College London, UK
| | - Valerie Wilson
- Centre for Regenerative Medicine, The University of Edinburgh, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, UK.
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16
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Malaguti M, Portero Migueles R, Annoh J, Sadurska D, Blin G, Lowell S. SyNPL: Synthetic Notch pluripotent cell lines to monitor and manipulate cell interactions in vitro and in vivo. Development 2022; 149:275525. [PMID: 35616331 PMCID: PMC9270970 DOI: 10.1242/dev.200226] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 05/13/2022] [Indexed: 12/11/2022]
Abstract
Cell-cell interactions govern differentiation and cell competition in pluripotent cells during early development, but the investigation of such processes is hindered by a lack of efficient analysis tools. Here, we introduce SyNPL: clonal pluripotent stem cell lines that employ optimised Synthetic Notch (SynNotch) technology to report cell-cell interactions between engineered ‘sender’ and ‘receiver’ cells in cultured pluripotent cells and chimaeric mouse embryos. A modular design makes it straightforward to adapt the system for programming differentiation decisions non-cell-autonomously in receiver cells in response to direct contact with sender cells. We demonstrate the utility of this system by enforcing neuronal differentiation at the boundary between two cell populations. In summary, we provide a new adaptation of SynNotch technology that could be used to identify cell interactions and to profile changes in gene or protein expression that result from direct cell-cell contact with defined cell populations in culture and in early embryos, and that can be customised to generate synthetic patterning of cell fate decisions. Summary: Optimised Synthetic Notch circuitry in mouse pluripotent stem cells provides a modular tool with which to monitor cell-cell interactions and program synthetic patterning of cell fates in culture and in embryos.
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Affiliation(s)
- Mattias Malaguti
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Rosa Portero Migueles
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Jennifer Annoh
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Daina Sadurska
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Guillaume Blin
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Sally Lowell
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
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17
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Naganathan SR, Popović M, Oates AC. Left-right symmetry of zebrafish embryos requires somite surface tension. Nature 2022; 605:516-521. [PMID: 35477753 DOI: 10.1038/s41586-022-04646-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/15/2022] [Indexed: 02/06/2023]
Abstract
The body axis of vertebrate embryos is periodically segmented into bilaterally symmetric pairs of somites1,2. The anteroposterior length of somites, their position and left-right symmetry are thought to be molecularly determined before somite morphogenesis3,4. Here we show that, in zebrafish embryos, initial somite anteroposterior lengths and positions are imprecise and, consequently, many somite pairs form left-right asymmetrically. Notably, these imprecisions are not left unchecked and we find that anteroposterior lengths adjust within an hour after somite formation, thereby increasing morphological symmetry. We find that anteroposterior length adjustments result entirely from changes in somite shape without change in somite volume, with changes in anteroposterior length being compensated by corresponding changes in mediolateral length. The anteroposterior adjustment mechanism is facilitated by somite surface tension, which we show by comparing in vivo experiments and in vitro single-somite explant cultures using a mechanical model. Length adjustment is inhibited by perturbation of molecules involved in surface tension, such as integrin and fibronectin. By contrast, the adjustment mechanism is unaffected by perturbations to the segmentation clock, therefore revealing a distinct process that influences morphological segment lengths. We propose that tissue surface tension provides a general mechanism to adjust shapes and ensure precision and symmetry of tissues in developing embryos.
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Affiliation(s)
- Sundar R Naganathan
- Institute of Bioengineering, École polytechnique fédérale de Lausanne, Lausanne, Switzerland.
| | - Marko Popović
- Institute of Physics, École polytechnique fédérale de Lausanne, Lausanne, Switzerland. .,Max Planck Institute for Physics of Complex Systems, Dresden, Germany. .,Center for Systems Biology Dresden, Dresden, Germany.
| | - Andrew C Oates
- Institute of Bioengineering, École polytechnique fédérale de Lausanne, Lausanne, Switzerland.
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18
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Sanaki-Matsumiya M, Matsuda M, Gritti N, Nakaki F, Sharpe J, Trivedi V, Ebisuya M. Periodic formation of epithelial somites from human pluripotent stem cells. Nat Commun 2022; 13:2325. [PMID: 35484123 PMCID: PMC9050736 DOI: 10.1038/s41467-022-29967-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 04/11/2022] [Indexed: 12/19/2022] Open
Abstract
During embryonic development, epithelial cell blocks called somites are periodically formed according to the segmentation clock, becoming the foundation for the segmental pattern of the vertebral column. The process of somitogenesis has recently been recapitulated with murine and human pluripotent stem cells. However, an in vitro model for human somitogenesis coupled with the segmentation clock and epithelialization is still missing. Here, we report the generation of human somitoids, organoids that periodically form pairs of epithelial somite-like structures. Somitoids display clear oscillations of the segmentation clock that coincide with the segmentation of the presomitic mesoderm. The resulting somites show anterior-posterior and apical-basal polarities. Matrigel is essential for epithelialization but dispensable for the differentiation into somite cells. The size of somites is rather constant, irrespective of the initial cell number. The amount of WNT signaling instructs the proportion of mesodermal lineages in somitoids. Somitoids provide a novel platform to study human somitogenesis. Somitogenesis has been well characterized in model organisms, resulting in detailed description of the somite segmentation clock. Here they generate somitogenic organoids from human pluripotent stem cells that recapitulate somitogenesis, periodic segmentation, and proper polarity.
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Affiliation(s)
| | - Mitsuhiro Matsuda
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain
| | - Nicola Gritti
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain
| | - Fumio Nakaki
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain
| | - James Sharpe
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain
| | - Vikas Trivedi
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain.,EMBL Heidelberg, Developmental Biology Unit, Heidelberg, Germany
| | - Miki Ebisuya
- European Molecular Biology Laboratory (EMBL) Barcelona, Barcelona, Spain.
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19
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Veenvliet JV, Lenne PF, Turner DA, Nachman I, Trivedi V. Sculpting with stem cells: how models of embryo development take shape. Development 2021; 148:dev192914. [PMID: 34908102 PMCID: PMC8722391 DOI: 10.1242/dev.192914] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During embryogenesis, organisms acquire their shape given boundary conditions that impose geometrical, mechanical and biochemical constraints. A detailed integrative understanding how these morphogenetic information modules pattern and shape the mammalian embryo is still lacking, mostly owing to the inaccessibility of the embryo in vivo for direct observation and manipulation. These impediments are circumvented by the developmental engineering of embryo-like structures (stembryos) from pluripotent stem cells that are easy to access, track, manipulate and scale. Here, we explain how unlocking distinct levels of embryo-like architecture through controlled modulations of the cellular environment enables the identification of minimal sets of mechanical and biochemical inputs necessary to pattern and shape the mammalian embryo. We detail how this can be complemented with precise measurements and manipulations of tissue biochemistry, mechanics and geometry across spatial and temporal scales to provide insights into the mechanochemical feedback loops governing embryo morphogenesis. Finally, we discuss how, even in the absence of active manipulations, stembryos display intrinsic phenotypic variability that can be leveraged to define the constraints that ensure reproducible morphogenesis in vivo.
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Affiliation(s)
- Jesse V. Veenvliet
- Stembryogenesis Lab, Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01307 Dresden, Germany
| | - Pierre-François Lenne
- Aix Marseille University, CNRS, IBDM, Turing Center for Living Systems, 13288, Marseille, France
| | - David A. Turner
- Institute of Life Course and Medical Sciences, William Henry Duncan Building, University of Liverpool, Liverpool, L7 8TX, UK
| | - Iftach Nachman
- School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Vikas Trivedi
- European Molecular Biology Laboratories (EMBL), Barcelona, 08003, Spain
- EMBL Heidelberg, Developmental Biology Unit, 69117, Heidelberg, Germany
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20
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Linde-Medina M, Smit TH. Molecular and Mechanical Cues for Somite Periodicity. Front Cell Dev Biol 2021; 9:753446. [PMID: 34901002 PMCID: PMC8663771 DOI: 10.3389/fcell.2021.753446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/14/2021] [Indexed: 11/13/2022] Open
Abstract
Somitogenesis refers to the segmentation of the paraxial mesoderm, a tissue located on the back of the embryo, into regularly spaced and sized pieces, i.e., the somites. This periodicity is important to assure, for example, the formation of a functional vertebral column. Prevailing models of somitogenesis are based on the existence of a gene regulatory network capable of generating a striped pattern of gene expression, which is subsequently translated into periodic tissue boundaries. An alternative view is that the pre-pattern that guides somitogenesis is not chemical, but of a mechanical origin. A striped pattern of mechanical strain can be formed in physically connected tissues expanding at different rates, as it occurs in the embryo. Here we argue that both molecular and mechanical cues could drive somite periodicity and suggest how they could be integrated.
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Affiliation(s)
| | - Theodoor H. Smit
- Department of Orthopaedic Surgery, Amsterdam Movement Sciences, Amsterdam University Medical Centres, Amsterdam, Netherlands
- Department of Medical Biology, Amsterdam University Medical Centres, Amsterdam, Netherlands
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21
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Piatkowska AM, Evans SE, Stern CD. Cellular aspects of somite formation in vertebrates. Cells Dev 2021; 168:203732. [PMID: 34391979 DOI: 10.1016/j.cdev.2021.203732] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/04/2021] [Accepted: 08/04/2021] [Indexed: 10/20/2022]
Abstract
Vertebrate segmentation, the process that generates a regular arrangement of somites and thereby establishes the pattern of the adult body and of the musculoskeletal and peripheral nervous systems, was noticed many centuries ago. In the last few decades, there has been renewed interest in the process and especially in the molecular mechanisms that might account for its regularity and other spatial-temporal properties. Several models have been proposed but surprisingly, most of these do not provide clear links between the molecular mechanisms and the cell behaviours that generate the segmental pattern. Here we present a short survey of our current knowledge about the cellular aspects of vertebrate segmentation and the similarities and differences between different vertebrate groups in how they achieve their metameric pattern. Taking these variations into account should help to assess each of the models more appropriately.
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Affiliation(s)
- Agnieszka M Piatkowska
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK.
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22
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Wang JX, White MD. Mechanical forces in avian embryo development. Semin Cell Dev Biol 2021; 120:133-146. [PMID: 34147339 DOI: 10.1016/j.semcdb.2021.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
Research using avian embryos has led to major conceptual advances in developmental biology, virology, immunology, genetics and cell biology. The avian embryo has several significant advantages, including ready availability and ease of accessibility, rapid development with marked similarities to mammals and a high amenability to manipulation. As mechanical forces are increasingly recognised as key drivers of morphogenesis, this powerful model system is shedding new light on the mechanobiology of embryonic development. Here, we highlight progress in understanding how mechanical forces direct key morphogenetic processes in the early avian embryo. Recent advances in quantitative live imaging and modelling are elaborating upon traditional work using physical models and embryo manipulations to reveal cell dynamics and tissue forces in ever greater detail. The recent application of transgenic technologies further increases the strength of the avian model and is providing important insights about previously intractable developmental processes.
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Affiliation(s)
- Jian Xiong Wang
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia
| | - Melanie D White
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, QLD 4072, Australia.
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23
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Abstract
Arthropod segmentation and vertebrate somitogenesis are leading fields in the experimental and theoretical interrogation of developmental patterning. However, despite the sophistication of current research, basic conceptual issues remain unresolved. These include: (i) the mechanistic origins of spatial organization within the segment addition zone (SAZ); (ii) the mechanistic origins of segment polarization; (iii) the mechanistic origins of axial variation; and (iv) the evolutionary origins of simultaneous patterning. Here, I explore these problems using coarse-grained models of cross-regulating dynamical processes. In the morphogenetic framework of a row of cells undergoing axial elongation, I simulate interactions between an 'oscillator', a 'switch' and up to three 'timers', successfully reproducing essential patterning behaviours of segmenting systems. By comparing the output of these largely cell-autonomous models to variants that incorporate positional information, I find that scaling relationships, wave patterns and patterning dynamics all depend on whether the SAZ is regulated by temporal or spatial information. I also identify three mechanisms for polarizing oscillator output, all of which functionally implicate the oscillator frequency profile. Finally, I demonstrate significant dynamical and regulatory continuity between sequential and simultaneous modes of segmentation. I discuss these results in the context of the experimental literature.
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Affiliation(s)
- Erik Clark
- Department of Systems Biology, Harvard Medical School, 210 Longwood Ave, Boston, MA 02115, USA
- Trinity College Cambridge, University of Cambridge, Trinity Street, Cambridge CB2 1TQ, UK
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24
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Affiliation(s)
- Jake Cornwall-Scoones
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - Magdalena Zernicka-Goetz
- California Institute of Technology, Division of Biology and Biological Engineering, 1200 E. California Boulevard, Pasadena, CA, 91125, USA; Mammalian Embryo and Stem Cell Group, University of Cambridge, Department of Physiology, Development and Neuroscience, Cambridge, CB2 3EG, UK.
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25
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Pantoja-Hernández J, Breña-Medina VF, Santillán M. Hybrid reaction-diffusion and clock-and-wavefront model for the arrest of oscillations in the somitogenesis segmentation clock. CHAOS (WOODBURY, N.Y.) 2021; 31:063107. [PMID: 34241318 DOI: 10.1063/5.0045460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/12/2021] [Indexed: 06/13/2023]
Abstract
The clock and wavefront paradigm is arguably the most widely accepted model for explaining the embryonic process of somitogenesis. According to this model, somitogenesis is based upon the interaction between a genetic oscillator, known as segmentation clock, and a differentiation wavefront, which provides the positional information indicating where each pair of somites is formed. Shortly after the clock and wavefront paradigm was introduced, Meinhardt presented a conceptually different mathematical model for morphogenesis in general, and somitogenesis in particular. Recently, Cotterell et al. [A local, self-organizing reaction-diffusion model can explain somite patterning in embryos, Cell Syst. 1, 257-269 (2015)] rediscovered an equivalent model by systematically enumerating and studying small networks performing segmentation. Cotterell et al. called it a progressive oscillatory reaction-diffusion (PORD) model. In the Meinhardt-PORD model, somitogenesis is driven by short-range interactions and the posterior movement of the front is a local, emergent phenomenon, which is not controlled by global positional information. With this model, it is possible to explain some experimental observations that are incompatible with the clock and wavefront model. However, the Meinhardt-PORD model has some important disadvantages of its own. Namely, it is quite sensitive to fluctuations and depends on very specific initial conditions (which are not biologically realistic). In this work, we propose an equivalent Meinhardt-PORD model and then amend it to couple it with a wavefront consisting of a receding morphogen gradient. By doing so, we get a hybrid model between the Meinhardt-PORD and the clock-and-wavefront ones, which overcomes most of the deficiencies of the two originating models.
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Affiliation(s)
- Jesús Pantoja-Hernández
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Vía del Conocimiento 201, Parque PIIT, 66628 Apodaca, NL, Mexico
| | | | - Moisés Santillán
- Centro de Investigación y de Estudios Avanzados del IPN, Unidad Monterrey, Vía del Conocimiento 201, Parque PIIT, 66628 Apodaca, NL, Mexico
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26
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Knudsen TB, Fitzpatrick SC, De Abrew KN, Birnbaum LS, Chappelle A, Daston GP, Dolinoy DC, Elder A, Euling S, Faustman EM, Fedinick KP, Franzosa JA, Haggard DE, Haws L, Kleinstreuer NC, Buck Louis GM, Mendrick DL, Rudel R, Saili KS, Schug TT, Tanguay RL, Turley AE, Wetmore BA, White KW, Zurlinden TJ. FutureTox IV Workshop Summary: Predictive Toxicology for Healthy Children. Toxicol Sci 2021; 180:198-211. [PMID: 33555348 PMCID: PMC8041457 DOI: 10.1093/toxsci/kfab013] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
FutureTox IV, a Society of Toxicology Contemporary Concepts in Toxicology workshop, was held in November 2018. Building upon FutureTox I, II, and III, this conference focused on the latest science and technology for in vitro profiling and in silico modeling as it relates to predictive developmental and reproductive toxicity (DART). Publicly available high-throughput screening data sets are now available for broad in vitro profiling of bioactivities across large inventories of chemicals. Coupling this vast amount of mechanistic data with a deeper understanding of molecular embryology and post-natal development lays the groundwork for using new approach methodologies (NAMs) to evaluate chemical toxicity, drug efficacy, and safety assessment for embryo-fetal development. NAM is a term recently adopted in reference to any technology, methodology, approach, or combination thereof that can be used to provide information on chemical hazard and risk assessment to avoid the use of intact animals (U.S. Environmental Protection Agency [EPA], Strategic plan to promote the development and implementation of alternative test methods within the tsca program, 2018, https://www.epa.gov/sites/production/files/2018-06/documents/epa_alt_strat_plan_6-20-18_clean_final.pdf). There are challenges to implementing NAMs to evaluate chemicals for developmental toxicity compared with adult toxicity. This forum article reviews the 2018 workshop activities, highlighting challenges and opportunities for applying NAMs for adverse pregnancy outcomes (eg, preterm labor, malformations, low birth weight) as well as disorders manifesting postnatally (eg, neurodevelopmental impairment, breast cancer, cardiovascular disease, fertility). DART is an important concern for different regulatory statutes and test guidelines. Leveraging advancements in such approaches and the accompanying efficiencies to detecting potential hazards to human development are the unifying concepts toward implementing NAMs in DART testing. Although use of NAMs for higher level regulatory decision making is still on the horizon, the conference highlighted novel testing platforms and computational models that cover multiple levels of biological organization, with the unique temporal dynamics of embryonic development, and novel approaches for estimating toxicokinetic parameters essential in supporting in vitro to in vivo extrapolation.
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Affiliation(s)
- Thomas B Knudsen
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | | | | | - Linda S Birnbaum
- National Institute of Environmental Health Science, NIH, Research Triangle Park, North Carolina, USA
| | - Anne Chappelle
- Chappelle Toxicology Consulting, LLC, Chadds Ford, Pennsylvania, USA
| | | | | | - Alison Elder
- University of Rochester, Rochester, New York, USA
| | - Susan Euling
- U.S. Environmental Protection Agency, Office of Children’s Health Protection, Washington, District of Columbia, USA
| | | | | | - Jill A Franzosa
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Derik E Haggard
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
- Oak Ridge Institute for Science and Education (ORISE);, Texas, USA
| | | | | | | | - Donna L Mendrick
- U.S. Food and Drug Administration, NCTR, Silver Spring, Maryland, USA
| | | | - Katerine S Saili
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Thaddeus T Schug
- National Institute of Environmental Health Science, NIH, Research Triangle Park, North Carolina, USA
| | | | | | - Barbara A Wetmore
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
| | - Kimberly W White
- American Chemistry Council, Washington, District of Columbia, USA
| | - Todd J Zurlinden
- U.S. Environmental Protection Agency, ORD, Research Triangle Park, North Carolina, USA
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27
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A mechanical model of early somite segmentation. iScience 2021; 24:102317. [PMID: 33889816 PMCID: PMC8050378 DOI: 10.1016/j.isci.2021.102317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 01/15/2021] [Accepted: 03/12/2021] [Indexed: 11/21/2022] Open
Abstract
Somitogenesis is often described using the clock-and-wavefront (CW) model, which does not explain how molecular signaling rearranges the pre-somitic mesoderm (PSM) cells into somites. Our scanning electron microscopy analysis of chicken embryos reveals a caudally-progressing epithelialization front in the dorsal PSM that precedes somite formation. Signs of apical constriction and tissue segmentation appear in this layer 3-4 somite lengths caudal to the last-formed somite. We propose a mechanical instability model in which a steady increase of apical contractility leads to periodic failure of adhesion junctions within the dorsal PSM and positions the future inter-somite boundaries. This model produces spatially periodic segments whose size depends on the speed of the activation front of contraction (F), and the buildup rate of contractility (Λ). The Λ/F ratio determines whether this mechanism produces spatially and temporally regular or irregular segments, and whether segment size increases with the front speed. Dorsal pre-somitic mesoderm of chicken embryos epithelializes before somite formation Dorsal epithelium shows signs of apical constriction and early segmentation A mechanical instability model can reproduce sequential segmentation A single ratio describes spatial and temporal patterns of segmentation
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28
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Veenvliet JV, Bolondi A, Kretzmer H, Haut L, Scholze-Wittler M, Schifferl D, Koch F, Guignard L, Kumar AS, Pustet M, Heimann S, Buschow R, Wittler L, Timmermann B, Meissner A, Herrmann BG. Mouse embryonic stem cells self-organize into trunk-like structures with neural tube and somites. Science 2021; 370:370/6522/eaba4937. [PMID: 33303587 DOI: 10.1126/science.aba4937] [Citation(s) in RCA: 151] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 05/13/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022]
Abstract
Post-implantation embryogenesis is a highly dynamic process comprising multiple lineage decisions and morphogenetic changes that are inaccessible to deep analysis in vivo. We found that pluripotent mouse embryonic stem cells (mESCs) form aggregates that upon embedding in an extracellular matrix compound induce the formation of highly organized "trunk-like structures" (TLSs) comprising the neural tube and somites. Comparative single-cell RNA sequencing analysis confirmed that this process is highly analogous to mouse development and follows the same stepwise gene-regulatory program. Tbx6 knockout TLSs developed additional neural tubes mirroring the embryonic mutant phenotype, and chemical modulation could induce excess somite formation. TLSs thus reveal an advanced level of self-organization and provide a powerful platform for investigating post-implantation embryogenesis in a dish.
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Affiliation(s)
- Jesse V Veenvliet
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
| | - Adriano Bolondi
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Helene Kretzmer
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Leah Haut
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.,Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Manuela Scholze-Wittler
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Dennis Schifferl
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Frederic Koch
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Léo Guignard
- Max Delbrück Center for Molecular Medicine and Berlin Institute of Health, 10115 Berlin, Germany
| | - Abhishek Sampath Kumar
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Milena Pustet
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Simon Heimann
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - René Buschow
- Microscopy and Cryo-Electron Microscopy, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Lars Wittler
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Bernd Timmermann
- Sequencing Core Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Alexander Meissner
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany. .,Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Bernhard G Herrmann
- Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany. .,Institute for Medical Genetics, Charité-University Medicine Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany
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Yoshioka-Kobayashi K, Kageyama R. Imaging and manipulating the segmentation clock. Cell Mol Life Sci 2021; 78:1221-1231. [PMID: 33015720 PMCID: PMC11072046 DOI: 10.1007/s00018-020-03655-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/21/2020] [Accepted: 09/22/2020] [Indexed: 11/29/2022]
Abstract
During embryogenesis, the processes that control how cells differentiate and interact to form particular tissues and organs with precise timing and shape are of fundamental importance. One prominent example of such processes is vertebrate somitogenesis, which is governed by a molecular oscillator called the segmentation clock. The segmentation clock system is initiated in the presomitic mesoderm in which a set of genes and signaling pathways exhibit coordinated spatiotemporal dynamics to establish regularly spaced boundaries along the body axis; these boundaries provide a blueprint for the development of segment-like structures such as spines and skeletal muscles. The highly complex and dynamic nature of this in vivo event and the design principles and their regulation in both normal and abnormal embryogenesis are not fully understood. Recently, live-imaging has been used to quantitatively analyze the dynamics of selected components of the circuit, particularly in combination with well-designed experiments to perturb the system. Here, we review recent progress from studies using live imaging and manipulation, including attempts to recapitulate the segmentation clock in vitro. In combination with mathematical modeling, these techniques have become essential for disclosing novel aspects of the clock.
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Affiliation(s)
- Kumiko Yoshioka-Kobayashi
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan.
- Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Kyoto, 606-8501, Japan.
| | - Ryoichiro Kageyama
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan.
- Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan.
- Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, 606-8501, Japan.
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30
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Veenvliet JV, Herrmann BG. Modeling mammalian trunk development in a dish. Dev Biol 2020; 474:5-15. [PMID: 33347872 DOI: 10.1016/j.ydbio.2020.12.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/04/2020] [Accepted: 12/13/2020] [Indexed: 12/17/2022]
Abstract
Mammalian post-implantation development comprises the coordination of complex lineage decisions and morphogenetic processes shaping the embryo. Despite technological advances, a comprehensive understanding of the dynamics of these processes and of the self-organization capabilities of stem cells and their descendants remains elusive. Building synthetic embryo-like structures from pluripotent embryonic stem cells in vitro promises to fill these knowledge gaps and thereby may prove transformative for developmental biology. Initial efforts to model the post-implantation embryo resulted in structures with compromised morphology (gastruloids). Recent approaches employing modified culture media, an extracellular matrix surrogate or extra-embryonic stem cells, however, succeeded in establishing embryo-like architecture. For example, embedding of gastruloids in Matrigel unlocked self-organization into trunk-like structures with bilateral somites and a neural tube-like structure, together with gut tissue and primordial germ cell-like cells. In this review, we describe the currently available models, discuss how these can be employed to acquire novel biological insights, and detail the imminent challenges for improving current models by in vitro engineering.
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Affiliation(s)
- Jesse V Veenvliet
- Dept. of Developmental Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195, Berlin, Germany
| | - Bernhard G Herrmann
- Dept. of Developmental Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195, Berlin, Germany; Institute for Medical Genetics, Charité - University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
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31
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Naganathan S, Oates A. Patterning and mechanics of somite boundaries in zebrafish embryos. Semin Cell Dev Biol 2020; 107:170-178. [DOI: 10.1016/j.semcdb.2020.04.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/12/2020] [Accepted: 04/19/2020] [Indexed: 12/12/2022]
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32
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Oates AC. Waiting on the Fringe: cell autonomy and signaling delays in segmentation clocks. Curr Opin Genet Dev 2020; 63:61-70. [PMID: 32505051 DOI: 10.1016/j.gde.2020.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/19/2020] [Accepted: 04/23/2020] [Indexed: 12/16/2022]
Abstract
The rhythmic and sequential segmentation of the vertebrate body axis into somites during embryogenesis is governed by a multicellular, oscillatory patterning system called the segmentation clock. Despite many overt similarities between vertebrates, differences in genetic and dynamic regulation have been reported, raising intriguing questions about the evolution and conservation of this fundamental patterning process. Recent studies have brought insights into two important and related issues: (1) whether individual cells of segmentation clocks are autonomous oscillators or require cell-cell communication for their rhythm; and (2) the role of delays in the cell-cell communication that synchronizes the population of genetic oscillators. Although molecular details differ between species, conservation may exist at the level of the dynamics, hinting at rules for evolutionary trajectories in the system.
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Affiliation(s)
- Andrew C Oates
- Institute of Bioengineering, School of Life Sciences and School of Engineering, Ecole Polytechnique Fédéral de Lausanne (EPFL), CH-1015, Switzerland.
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33
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Fortuna I, Perrone GC, Krug MS, Susin E, Belmonte JM, Thomas GL, Glazier JA, de Almeida RMC. CompuCell3D Simulations Reproduce Mesenchymal Cell Migration on Flat Substrates. Biophys J 2020; 118:2801-2815. [PMID: 32407685 PMCID: PMC7264849 DOI: 10.1016/j.bpj.2020.04.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/20/2020] [Accepted: 04/20/2020] [Indexed: 11/16/2022] Open
Abstract
Mesenchymal cell crawling is a critical process in normal development, in tissue function, and in many diseases. Quantitatively predictive numerical simulations of cell crawling thus have multiple scientific, medical, and technological applications. However, we still lack a low-computational-cost approach to simulate mesenchymal three-dimensional (3D) cell crawling. Here, we develop a computationally tractable 3D model (implemented as a simulation in the CompuCell3D simulation environment) of mesenchymal cells crawling on a two-dimensional substrate. The Fürth equation, the usual characterization of mean-squared displacement (MSD) curves for migrating cells, describes a motion in which, for increasing time intervals, cell movement transitions from a ballistic to a diffusive regime. Recent experiments have shown that for very short time intervals, cells exhibit an additional fast diffusive regime. Our simulations' MSD curves reproduce the three experimentally observed temporal regimes, with fast diffusion for short time intervals, slow diffusion for long time intervals, and intermediate time -interval-ballistic motion. The resulting parameterization of the trajectories for both experiments and simulations allows the definition of time- and length scales that translate between computational and laboratory units. Rescaling by these scales allows direct quantitative comparisons among MSD curves and between velocity autocorrelation functions from experiments and simulations. Although our simulations replicate experimentally observed spontaneous symmetry breaking, short-timescale diffusive motion, and spontaneous cell-motion reorientation, their computational cost is low, allowing their use in multiscale virtual-tissue simulations. Comparisons between experimental and simulated cell motion support the hypothesis that short-time actomyosin dynamics affects longer-time cell motility. The success of the base cell-migration simulation model suggests its future application in more complex situations, including chemotaxis, migration through complex 3D matrices, and collective cell motion.
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Affiliation(s)
- Ismael Fortuna
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Gabriel C Perrone
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Monique S Krug
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Eduarda Susin
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Julio M Belmonte
- Biocomplexity Institute and Department of Intelligent Systems Engineering, Indiana University, Bloomington, Indiana; Department of Physics, North Carolina State University, Raleigh, North Carolina
| | - Gilberto L Thomas
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
| | - James A Glazier
- Biocomplexity Institute and Department of Intelligent Systems Engineering, Indiana University, Bloomington, Indiana
| | - Rita M C de Almeida
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Instituto Nacional de Ciência e Tecnologia, Sistemas Complexos, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Program de Pós Graduação em Bioinformática, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
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34
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Durston AJ. A Tribute to Lewis Wolpert and His Ideas on the 50th Anniversary of the Publication of His Paper 'Positional Information and the Spatial Pattern of Differentiation'. Evidence for a Timing Mechanism for Setting Up the Vertebrate Anterior-Posterior (A-P) Axis. Int J Mol Sci 2020; 21:E2552. [PMID: 32272563 PMCID: PMC7177403 DOI: 10.3390/ijms21072552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 11/16/2022] Open
Abstract
This article is a tribute to Lewis Wolpert and his ideas on the occasion of the recent 50th anniversary of the publication of his article 'Positional Information and the Spatial Pattern of Differentiation'. This tribute relates to another one of his ideas: his early 'Progress Zone' timing model for limb development. Recent evidence is reviewed showing a mechanism sharing features with this model patterning the main body axis in early vertebrate development. This tribute celebrates the golden era of Developmental Biology.
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Affiliation(s)
- Antony J Durston
- Institute of Biology, University of Leiden, Sylvius Laboratory, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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35
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Nelemans BKA, Schmitz M, Tahir H, Merks RMH, Smit TH. Somite Division and New Boundary Formation by Mechanical Strain. iScience 2020; 23:100976. [PMID: 32222696 PMCID: PMC7109633 DOI: 10.1016/j.isci.2020.100976] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/30/2020] [Accepted: 03/09/2020] [Indexed: 02/04/2023] Open
Abstract
Somitogenesis, the primary segmentation of the vertebrate embryo, is associated with oscillating genes that interact with a wave of cell differentiation. The necessity of cell-matrix adherence and embryonic tension, however, suggests that mechanical cues are also involved. To explicitly investigate this, we applied surplus axial strain to live chick embryos. Despite substantial deformations, the embryos developed normally and somite formation rate was unaffected. Surprisingly, however, we observed slow cellular reorganizations of the most elongated somites into two or more well-shaped daughter somites. In what appeared to be a regular process of boundary formation, somites divided and fibronectin was deposited in between. Cell counts and morphology indicated that cells from the somitocoel underwent mesenchymal-epithelial transition; this was supported by a Cellular Potts model of somite division. Thus, although somitogenesis appeared to be extremely robust, we observed new boundary formation in existing somites and conclude that mechanical strain can be morphologically instructive. Live chick embryos develop normally under substantial axial strain (>50%) Mature somites divide into daughter somites, and fibronectin is deposited in between Mesenchymal cells from the somitocoel transition into epithelial border cells Mechanical strain can induce border formation and thus affect morphogenesis
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Affiliation(s)
- Ben K A Nelemans
- Department of Orthopaedic Surgery, Amsterdam University Medical Centres, Amsterdam Movement Sciences, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands
| | - Manuel Schmitz
- Department of Orthopaedic Surgery, Amsterdam University Medical Centres, Amsterdam Movement Sciences, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands
| | - Hannan Tahir
- Department of Orthopaedic Surgery, Amsterdam University Medical Centres, Amsterdam Movement Sciences, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands; Centrum Wiskunde & Informatica, Science Park 123, 1098 XG Amsterdam, the Netherlands
| | - Roeland M H Merks
- Centrum Wiskunde & Informatica, Science Park 123, 1098 XG Amsterdam, the Netherlands; Mathematical Institute Leiden, Leiden University, Niels Bohrweg 1, 2333 CA Leiden, the Netherlands
| | - Theodoor H Smit
- Department of Orthopaedic Surgery, Amsterdam University Medical Centres, Amsterdam Movement Sciences, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands; Department of Medical Biology, Amsterdam University Medical Centres, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands.
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36
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Naoki H, Matsui T. Somite boundary determination in normal and clock-less vertebrate embryos. Dev Growth Differ 2020; 62:177-187. [PMID: 32108939 DOI: 10.1111/dgd.12655] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/31/2020] [Accepted: 02/01/2020] [Indexed: 12/21/2022]
Abstract
Vertebrate segments called somites are generated by periodic segmentation of the presomitic mesoderm (PSM). In the most accepted theoretical model for somite segmentation, the clock and wavefront (CW) model, a clock that ticks to determine particular timings and a wavefront that moves posteriorly are presented in the PSM, and somite positions are determined when the clock meets the posteriorly moving wavefront somewhere in the PSM. Over the last two decades, it has been revealed that the molecular mechanism of the clock and wavefront in vertebrates is based on clock genes including Hes family transcription factors and Notch effectors that oscillate within the PSM to determine particular timings and fibroblast growth factor (FGF) gradients, acting as the posteriorly moving wavefront to determine the position of somite segmentation. A clock-less condition in the CW model was predicted to form no somites; however, irregularly sized somites were still formed in mice and zebrafish, suggesting that this was one of the limitations of the CW model. Recently, we performed interdisciplinary research of experimental and theoretical biological studies and revealed the mechanisms of somite boundary determination in normal and clock-less conditions by characterization of the FGF/extracellular signal-regulated kinase (ERK) activity dynamics. Since features of the molecular clock have already been described in-depth in several reviews, we summarized recent findings regarding the role of FGF/ERK signaling in somite boundary formation and described our current understanding of how FGF/ERK signaling contributes to somitogenesis in normal and clock-less conditions in this review.
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Affiliation(s)
- Honda Naoki
- Laboratory of Theoretical Biology, Research Center for Dynamic Living Systems, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto, Japan
| | - Takaaki Matsui
- Gene Regulation Research, Division of Biological Science, Nara Institute of Science and Technology, Takayama, Nara, Japan
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37
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Schweisguth F, Corson F. Self-Organization in Pattern Formation. Dev Cell 2020; 49:659-677. [PMID: 31163171 DOI: 10.1016/j.devcel.2019.05.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 02/16/2019] [Accepted: 05/07/2019] [Indexed: 12/19/2022]
Abstract
Self-organization is pervasive in development, from symmetry breaking in the early embryo to tissue patterning and morphogenesis. For a few model systems, the underlying molecular and cellular processes are now sufficiently characterized that mathematical models can be confronted with experiments, to explore the dynamics of pattern formation. Here, we review selected systems, ranging from cyanobacteria to mammals, where different forms of cell-cell communication, acting alone or together with positional cues, drive the patterning of cell fates, highlighting the insights that even very simple models can provide as well as the challenges on the path to a predictive understanding of development.
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Affiliation(s)
- François Schweisguth
- Institut Pasteur, Department of Developmental and Stem Cell Biology F-75015 Paris, France; CNRS, UMR 3738 F-75015 Paris, France.
| | - Francis Corson
- Laboratoire de Physique de l'Ecole Normale Supérieure, CNRS, Sorbonne Université, Université Paris Diderot 75005 Paris, France.
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38
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Durston AJ. Some Questions and Answers About the Role of Hox Temporal Collinearity in Vertebrate Axial Patterning. Front Cell Dev Biol 2019; 7:257. [PMID: 31850338 PMCID: PMC6895010 DOI: 10.3389/fcell.2019.00257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 10/16/2019] [Indexed: 01/02/2023] Open
Abstract
The vertebrate anterior-posterior (A-P = craniocaudal) axis is evidently made by a timing mechanism. Evidence has accumulated that tentatively identifies the A-P timer as being or involving Hox temporal collinearity (TC). Here, I focus on the two current competing models based on this premise. Common features and points of dissent are examined and a common model is distilled from what remains. This is an attempt to make sense of the literature.
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Gene expression profiling of skeletal myogenesis in human embryonic stem cells reveals a potential cascade of transcription factors regulating stages of myogenesis, including quiescent/activated satellite cell-like gene expression. PLoS One 2019; 14:e0222946. [PMID: 31560727 PMCID: PMC6764674 DOI: 10.1371/journal.pone.0222946] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/10/2019] [Indexed: 01/05/2023] Open
Abstract
Human embryonic stem cell (hESC)-derived skeletal muscle progenitors (SMP)—defined as PAX7-expressing cells with myogenic potential—can provide an abundant source of donor material for muscle stem cell therapy. As in vitro myogenesis is decoupled from in vivo timing and 3D-embryo structure, it is important to characterize what stage or type of muscle is modeled in culture. Here, gene expression profiling is analyzed in hESCs over a 50 day skeletal myogenesis protocol and compared to datasets of other hESC-derived skeletal muscle and adult murine satellite cells. Furthermore, day 2 cultures differentiated with high or lower concentrations of CHIR99021, a GSK3A/GSK3B inhibitor, were contrasted. Expression profiling of the 50 day time course identified successively expressed gene subsets involved in mesoderm/paraxial mesoderm induction, somitogenesis, and skeletal muscle commitment/formation which could be regulated by a putative cascade of transcription factors. Initiating differentiation with higher CHIR99021 concentrations significantly increased expression of MSGN1 and TGFB-superfamily genes, notably NODAL, resulting in enhanced paraxial mesoderm and reduced ectoderm/neuronal gene expression. Comparison to adult satellite cells revealed that genes expressed in 50-day cultures correlated better with those expressed by quiescent or early activated satellite cells, which have the greatest therapeutic potential. Day 50 cultures were similar to other hESC-derived skeletal muscle and both expressed known and novel SMP surface proteins. Overall, a putative cascade of transcription factors has been identified which regulates four stages of myogenesis. Subsets of these factors were upregulated by high CHIR99021 or their binding sites were significantly over-represented during SMP activation, ranging from quiescent to late-activated stages. This analysis serves as a resource to further study the progression of in vitro skeletal myogenesis and could be mined to identify novel markers of pluripotent-derived SMPs or regulatory transcription/growth factors. Finally, 50-day hESC-derived SMPs appear similar to quiescent/early activated satellite cells, suggesting they possess therapeutic potential.
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Kim E, Li J, Kang M, Kelly DL, Chen S, Napolitano A, Panzella L, Shi X, Yan K, Wu S, Shen J, Bentley WE, Payne GF. Redox Is a Global Biodevice Information Processing Modality. PROCEEDINGS OF THE IEEE. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS 2019; 107:1402-1424. [PMID: 32095023 PMCID: PMC7036710 DOI: 10.1109/jproc.2019.2908582] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Biology is well-known for its ability to communicate through (i) molecularly-specific signaling modalities and (ii) a globally-acting electrical modality associated with ion flow across biological membranes. Emerging research suggests that biology uses a third type of communication modality associated with a flow of electrons through reduction/oxidation (redox) reactions. This redox signaling modality appears to act globally and has features of both molecular and electrical modalities: since free electrons do not exist in aqueous solution, the electrons must flow through molecular intermediates that can be switched between two states - with electrons (reduced) or without electrons (oxidized). Importantly, this global redox modality is easily accessible through its electrical features using convenient electrochemical instrumentation. In this review, we explain this redox modality, describe our electrochemical measurements, and provide four examples demonstrating that redox enables communication between biology and electronics. The first two examples illustrate how redox probing can acquire biologically relevant information. The last two examples illustrate how redox inputs can transduce biologically-relevant transitions for patterning and the induction of a synbio transceiver for two-hop molecular communication. In summary, we believe redox provides a unique ability to bridge bio-device communication because simple electrochemical methods enable global access to biologically meaningful information. Further, we envision that redox may facilitate the application of information theory to the biological sciences.
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Affiliation(s)
- Eunkyoung Kim
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - Jinyang Li
- Institute for Bioscience & Biotechnology Research, Fischell Department of Bioengineering University of Maryland, College Park, MD 20742, USA
| | - Mijeong Kang
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - Deanna L Kelly
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21228, USA
| | - Shuo Chen
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21228, USA
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126 Naples, Italy
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126 Naples, Italy
| | - Xiaowen Shi
- School of Resource and Environmental Science, Hubei Biomass-Resource Chemistry, Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan 430079, China
| | - Kun Yan
- School of Resource and Environmental Science, Hubei Biomass-Resource Chemistry, Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan 430079, China
| | - Si Wu
- School of Resource and Environmental Science, Hubei Biomass-Resource Chemistry, Environmental Biotechnology Key Laboratory, Wuhan University, Wuhan 430079, China
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | - William E Bentley
- Institute for Bioscience & Biotechnology Research, Fischell Department of Bioengineering University of Maryland, College Park, MD 20742, USA
| | - Gregory F Payne
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
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41
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Durston AJ. What are the roles of retinoids, other morphogens, and Hox genes in setting up the vertebrate body axis? Genesis 2019; 57:e23296. [PMID: 31021058 PMCID: PMC6767176 DOI: 10.1002/dvg.23296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/24/2019] [Accepted: 03/29/2019] [Indexed: 01/09/2023]
Abstract
This article is concerned with the roles of retinoids and other known anterior-posterior morphogens in setting up the embryonic vertebrate anterior-posterior axis. The discussion is restricted to the very earliest events in setting up the anterior-posterior axis (from blastula to tailbud stages in Xenopus embryos). In these earliest developmental stages, morphogen concentration gradients are not relevant for setting up this axis. It emerges that at these stages, the core patterning mechanism is timing: BMP-anti BMP mediated time space translation that regulates Hox temporal and spatial collinearities and Hox-Hox auto- and cross- regulation. The known anterior-posterior morphogens and signaling pathways--retinoids, FGF's, Cdx, Wnts, Gdf11 and others--interact with this core mechanism at and after space-time defined "decision points," leading to the separation of distinct axial domains. There are also other roles for signaling pathways. Besides the Hox regulated hindbrain/trunk part of the axis, there is a rostral part (including the anterior part of the head and the extreme anterior domain [EAD]) that appears to be regulated by additional mechanisms. Key aspects of anterior-posterior axial patterning, including: the nature of different phases in early patterning and in the whole process; the specificities of Hox action and of intercellular signaling; and the mechanisms of Hox temporal and spatial collinearities, are discussed in relation to the facts and hypotheses proposed above.
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42
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Abstract
Hox temporal collinearity (TC) is a mysterious feature of embryogenesis. This article is opportune because of a recent challenge to TC’s existence This challenge is examined and the evidence that TC does exist is presented. Its function is discussed. Temporal collinearity is thought to be important because it lays the basis for Hox spatial collinearity and the vertebrate A-P axial pattern. The time-space translation mechanism whereby this occurs is examined.
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Affiliation(s)
- A J Durston
- a Institute of Biology , University of Leiden, Sylvius Laboratory , Leiden , Netherlands
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43
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Naoki H, Akiyama R, Sari DWK, Ishii S, Bessho Y, Matsui T. Noise-resistant developmental reproducibility in vertebrate somite formation. PLoS Comput Biol 2019; 15:e1006579. [PMID: 30716091 PMCID: PMC6361423 DOI: 10.1371/journal.pcbi.1006579] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 10/04/2018] [Indexed: 01/17/2023] Open
Abstract
The reproducibility of embryonic development is remarkable, although molecular processes are intrinsically stochastic at the single-cell level. How the multicellular system resists the inevitable noise to acquire developmental reproducibility constitutes a fundamental question in developmental biology. Toward this end, we focused on vertebrate somitogenesis as a representative system, because somites are repeatedly reproduced within a single embryo whereas such reproducibility is lost in segmentation clock gene-deficient embryos. However, the effect of noise on developmental reproducibility has not been fully investigated, because of the technical difficulty in manipulating the noise intensity in experiments. In this study, we developed a computational model of ERK-mediated somitogenesis, in which bistable ERK activity is regulated by an FGF gradient, cell-cell communication, and the segmentation clock, subject to the intrinsic noise. The model simulation generated our previous in vivo observation that the ERK activity was distributed in a step-like gradient in the presomitic mesoderm, and its boundary was posteriorly shifted by the clock in a stepwise manner, leading to regular somite formation. Here, we showed that this somite regularity was robustly maintained against the noise. Removing the clock from the model predicted that the stepwise shift of the ERK activity occurs at irregular timing with irregular distance owing to the noise, resulting in somite size variation. This model prediction was recently confirmed by live imaging of ERK activity in zebrafish embryos. Through theoretical analysis, we presented a mechanism by which the clock reduces the inherent somite irregularity observed in clock-deficient embryos. Therefore, this study indicates a novel role of the segmentation clock in noise-resistant developmental reproducibility. The segmentation clock has been widely considered vital for somite formation, because clock-deficient embryos display severe segmental defects. However, irregular somites are still formed, suggesting that the clock is not required for somite formation itself but rather endows it with developmental reproducibility. Thus, the following questions arose: How do irregular somites emerge in a clock-independent manner? How is the irregularity reduced in the presence of the clock? To address these questions, we developed a computational model of somitogenesis. We then clarified that the intrinsic noise induces spontaneous formation of irregular-sized somites in the absence of the clock, and that the clock plays an important role in suppressing the noise effect for reproducible somite formation.
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Affiliation(s)
- Honda Naoki
- Laboratory of Theoretical Biology, Research Center for Dynamic Living Systems, Graduate School of Biostudies, Kyoto University, Yoshidakonoecho, Sakyo, Kyoto, Japan
- * E-mail:
| | - Ryutaro Akiyama
- Gene Regulation Research, Division of Biological Science, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Dini Wahyu Kartika Sari
- Gene Regulation Research, Division of Biological Science, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Shin Ishii
- Graduate School of Informatics, Kyoto University, Yoshidahonmachi, Sakyo, Kyoto, Japan
| | - Yasumasa Bessho
- Gene Regulation Research, Division of Biological Science, Nara Institute of Science and Technology, Takayama, Nara, Japan
| | - Takaaki Matsui
- Gene Regulation Research, Division of Biological Science, Nara Institute of Science and Technology, Takayama, Nara, Japan
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44
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Durston AJ. Two Tier Hox Collinearity Mediates Vertebrate Axial Patterning. Front Cell Dev Biol 2018; 6:102. [PMID: 30234110 PMCID: PMC6131192 DOI: 10.3389/fcell.2018.00102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/10/2018] [Indexed: 12/04/2022] Open
Abstract
A two tier mechanism mediates Hox collinearity. Besides the familiar collinear chromatin modification within each Hox cluster (nanocollinearity), there is also a macrocollinearity tier. Individual Hox clusters and individual cells are coordinated and synchronized to generate multiscale (macro and nano) collinearity in the early vertebrate embryo. Macro-collinearity is mediated by three non-cell autonomous Hox–Hox interactions. These mediate temporal collinearity in early NOM (non-organizer mesoderm), time space translation where temporal collinearity is translated to spatial collinearity along the early embryo’s main body axis and neural transformation, where Hox expression is copied monospecifically from NOM mesoderm to overlying neurectoderm in the late gastrula. Unlike nanocollinearity, which is Hox cluster restricted, axial macrocollinearity extends into the head and EAD domains, thus covering the whole embryonic anterior-posterior (A-P) axis. EAD: extreme anterior domain, the only A-P axial domain anterior to the head. The whole time space translation mechanism interacts with A-P signaling pathways via “decision points,” separating different domains on the axis.
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Affiliation(s)
- Antony J Durston
- Faculty of Science, Institute of Biology Leiden, Leiden University, Leiden, Netherlands
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Ward L, Pang ASW, Evans SE, Stern CD. The role of the notochord in amniote vertebral column segmentation. Dev Biol 2018; 439:3-18. [PMID: 29654746 PMCID: PMC5971204 DOI: 10.1016/j.ydbio.2018.04.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/05/2018] [Accepted: 04/09/2018] [Indexed: 11/22/2022]
Abstract
The vertebral column is segmented, comprising an alternating series of vertebrae and intervertebral discs along the head-tail axis. The vertebrae and outer portion (annulus fibrosus) of the disc are derived from the sclerotome part of the somites, whereas the inner nucleus pulposus of the disc is derived from the notochord. Here we investigate the role of the notochord in vertebral patterning through a series of microsurgical experiments in chick embryos. Ablation of the notochord causes loss of segmentation of vertebral bodies and discs. However, the notochord cannot segment in the absence of the surrounding sclerotome. To test whether the notochord dictates sclerotome segmentation, we grafted an ectopic notochord. We find that the intrinsic segmentation of the sclerotome is dominant over any segmental information the notochord may possess, and no evidence that the chick notochord is intrinsically segmented. We propose that the segmental pattern of vertebral bodies and discs in chick is dictated by the sclerotome, which first signals to the notochord to ensure that the nucleus pulposus develops in register with the somite-derived annulus fibrosus. Later, the notochord is required for maintenance of sclerotome segmentation as the mature vertebral bodies and intervertebral discs form. These results highlight differences in vertebral development between amniotes and teleosts including zebrafish, where the notochord dictates the segmental pattern. The relative importance of the sclerotome and notochord in vertebral patterning has changed significantly during evolution. The chick notochord has no intrinsic segmentation. Neither notochord or sclerotome can segment normally without the other. The notochord attracts sclerotome cells to the midline. Vertebral segmentation involves reciprocal signals between notochord and sclerotome.
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Affiliation(s)
- Lizzy Ward
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Angel S W Pang
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, U.K..
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Kohsokabe T, Kaneko K. Boundary-induced pattern formation from uniform temporal oscillation. CHAOS (WOODBURY, N.Y.) 2018; 28:045110. [PMID: 31906628 DOI: 10.1063/1.5013280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pattern dynamics triggered by fixing a boundary is investigated. By considering a reaction-diffusion equation that has a unique spatially uniform and limit cycle attractor under a periodic or Neumann boundary condition, and then by choosing a fixed boundary condition, we found three novel phases depending on the ratio of diffusion constants of activator to inhibitor: transformation of temporally periodic oscillation into a spatially periodic fixed pattern, travelling wave emitted from the boundary, and aperiodic spatiotemporal dynamics. The transformation into a fixed, periodic pattern is analyzed by crossing of local nullclines at each spatial point, shifted by diffusion terms, as is analyzed by using recursive equations, to obtain the spatial pattern as an attractor. The generality of the boundary-induced pattern formation as well as its relevance to biological morphogenesis is discussed.
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Affiliation(s)
- Takahiro Kohsokabe
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Kunihiko Kaneko
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
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47
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Scialli AR, Daston G, Chen C, Coder PS, Euling SY, Foreman J, Hoberman AM, Hui J, Knudsen T, Makris SL, Morford L, Piersma AH, Stanislaus D, Thompson KE. Rethinking developmental toxicity testing: Evolution or revolution? Birth Defects Res 2018; 110:840-850. [PMID: 29436169 DOI: 10.1002/bdr2.1212] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/18/2017] [Accepted: 01/29/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND Current developmental toxicity testing adheres largely to protocols suggested in 1966 involving the administration of test compound to pregnant laboratory animals. After more than 50 years of embryo-fetal development testing, are we ready to consider a different approach to human developmental toxicity testing? METHODS A workshop was held under the auspices of the Developmental and Reproductive Toxicology Technical Committee of the ILSI Health and Environmental Sciences Institute to consider how we might design developmental toxicity testing if we started over with 21st century knowledge and techniques (revolution). We first consider what changes to the current protocols might be recommended to make them more predictive for human risk (evolution). RESULTS The evolutionary approach includes modifications of existing protocols and can include humanized models, disease models, more accurate assessment and testing of metabolites, and informed approaches to dose selection. The revolution could start with hypothesis-driven testing where we take what we know about a compound or close analog and answer specific questions using targeted experimental techniques rather than a one-protocol-fits-all approach. Central to the idea of hypothesis-driven testing is the concept that testing can be done at the level of mode of action. It might be feasible to identify a small number of key events at a molecular or cellular level that predict an adverse outcome and for which testing could be performed in vitro or in silico or, rarely, using limited in vivo models. Techniques for evaluating these key events exist today or are in development. DISCUSSION Opportunities exist for refining and then replacing current developmental toxicity testing protocols using techniques that have already been developed or are within reach.
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Affiliation(s)
- Anthony R Scialli
- Reproductive Toxicology Center and Scialli Consulting LLC, Washington, DC
| | | | - Connie Chen
- ILSI Health and Environmental Sciences Institute, Washington, DC
| | | | - Susan Y Euling
- Office of Children's Health Protection, U.S. Environmental Protection Agency, Washington, DC
| | | | | | - Julia Hui
- Celgene Corporation, Summit, New Jersey
| | - Thomas Knudsen
- National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Susan L Makris
- National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, DC
| | | | - Aldert H Piersma
- Center for Health Protection, National Institute for Public Health and the Environment RIVM, Bilthoven and Institute for Risk Assessment Sciences, Utrecht University, Utrecht, Netherlands
| | | | - Kary E Thompson
- Drug Safety Evaluation, Bristol-Myers Squibb, New Brunswick, New Jersey
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Abstract
Segmentation is the partitioning of the body axis into a series of repeating units or segments. This widespread body plan is found in annelids, arthropods, and chordates, showing it to be a successful developmental strategy for growing and generating diverse morphology and anatomy. Segmentation has been extensively studied over the years. Forty years ago, Cooke and Zeeman published the Clock and Wavefront model, creating a theoretical framework of how developing cells could acquire and keep temporal and spatial information in order to generate a segmented pattern. Twenty years later, in 1997, Palmeirim and co-workers found the first clock gene whose oscillatory expression pattern fitted within Cooke and Zeeman's model. Currently, in 2017, new experimental techniques, such as new ex vivo experimental models, real-time imaging of gene expression, live single cell tracking, and simplified transgenics approaches, are revealing some of the fine details of the molecular processes underlying the inner workings of the segmentation mechanisms, bringing new insights into this fundamental process. Here we review and discuss new emerging views that further our understanding of the vertebrate segmentation clock, with a particular emphasis on recent publications that challenge and/or complement the currently accepted Clock and Wavefront model.
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Affiliation(s)
- Tomás Pais-de-Azevedo
- Algarve Biomedical Center, Faro, Portugal
- CBMR, Centre for Biomedical Research, University of Algarve, Faro, Portugal
| | - Ramiro Magno
- Algarve Biomedical Center, Faro, Portugal
- CBMR, Centre for Biomedical Research, University of Algarve, Faro, Portugal
- Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, Netherlands
| | - Isabel Duarte
- Algarve Biomedical Center, Faro, Portugal
- CBMR, Centre for Biomedical Research, University of Algarve, Faro, Portugal
| | - Isabel Palmeirim
- Algarve Biomedical Center, Faro, Portugal
- CBMR, Centre for Biomedical Research, University of Algarve, Faro, Portugal
- Department of Biomedical Sciences and Medicine, University of Algarve, Faro, Portugal
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49
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Yan K, Liu Y, Zhang J, Correa SO, Shang W, Tsai CC, Bentley WE, Shen J, Scarcelli G, Raub CB, Shi XW, Payne GF. Electrical Programming of Soft Matter: Using Temporally Varying Electrical Inputs To Spatially Control Self Assembly. Biomacromolecules 2017; 19:364-373. [PMID: 29244943 DOI: 10.1021/acs.biomac.7b01464] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The growing importance of hydrogels in translational medicine has stimulated the development of top-down fabrication methods, yet often these methods lack the capabilities to generate the complex matrix architectures observed in biology. Here we show that temporally varying electrical signals can cue a self-assembling polysaccharide to controllably form a hydrogel with complex internal patterns. Evidence from theory and experiment indicate that internal structure emerges through a subtle interplay between the electrical current that triggers self-assembly and the electrical potential (or electric field) that recruits and appears to orient the polysaccharide chains at the growing gel front. These studies demonstrate that short sequences (minutes) of low-power (∼1 V) electrical inputs can provide the program to guide self-assembly that yields hydrogels with stable, complex, and spatially varying structure and properties.
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Affiliation(s)
- Kun Yan
- School of Resource and Environmental Science, Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and Energy, Wuhan University , Wuhan 430079, China
| | - Yi Liu
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park , College Park, Maryland 20742, United States.,Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
| | - Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
| | - Santiago O Correa
- Department of Biomedical Engineering, The Catholic University of America , Washington, D.C. 20064, United States
| | - Wu Shang
- Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
| | - Cheng-Chieh Tsai
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy , Baltimore, Maryland 21201, United States
| | - William E Bentley
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park , College Park, Maryland 20742, United States.,Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy , Baltimore, Maryland 21201, United States
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
| | - Christopher B Raub
- Department of Biomedical Engineering, The Catholic University of America , Washington, D.C. 20064, United States
| | - Xiao-Wen Shi
- School of Resource and Environmental Science, Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and Energy, Wuhan University , Wuhan 430079, China
| | - Gregory F Payne
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park , College Park, Maryland 20742, United States.,Fischell Department of Bioengineering, University of Maryland College Park , College Park, Maryland 20742, United States
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50
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In Vivo Human Somitogenesis Guides Somite Development from hPSCs. Cell Rep 2017; 18:1573-1585. [PMID: 28178531 DOI: 10.1016/j.celrep.2017.01.040] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 12/09/2016] [Accepted: 01/16/2017] [Indexed: 11/23/2022] Open
Abstract
Somites form during embryonic development and give rise to unique cell and tissue types, such as skeletal muscles and bones and cartilage of the vertebrae. Using somitogenesis-stage human embryos, we performed transcriptomic profiling of human presomitic mesoderm as well as nascent and developed somites. In addition to conserved pathways such as WNT-β-catenin, we also identified BMP and transforming growth factor β (TGF-β) signaling as major regulators unique to human somitogenesis. This information enabled us to develop an efficient protocol to derive somite cells in vitro from human pluripotent stem cells (hPSCs). Importantly, the in-vitro-differentiating cells progressively expressed markers of the distinct developmental stages that are known to occur during in vivo somitogenesis. Furthermore, when subjected to lineage-specific differentiation conditions, the hPSC-derived somite cells were multipotent in generating somite derivatives, including skeletal myocytes, osteocytes, and chondrocytes. This work improves our understanding of human somitogenesis and may enhance our ability to treat diseases affecting somite derivatives.
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