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Anjum S, Vijayraghavan D, Fernandez-Gonzalez R, Sutherland A, Davidson L. Inferring active and passive mechanical drivers of epithelial convergent extension. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2025:2025.01.28.635314. [PMID: 39975291 PMCID: PMC11838355 DOI: 10.1101/2025.01.28.635314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/21/2025]
Abstract
What can we learn about the mechanical processes that shape tissues by simply watching? Several schemes suggest that static cell morphology or junctional connectivity can reveal where chains of cells transmit force or where force asymmetries drive cellular rearrangements. We hypothesize that dynamic cell shape changes from time lapse sequences can be used to distinguish specific mechanisms of tissue morphogenesis. Convergent extension (CE) is a crucial developmental motif wherein a planar tissue narrows in one direction and lengthens in the other. It is tempting to assume that forces driving CE reside within cells of the deforming tissue, as CE may reflect a variety of active processes or passive responses to forces generated by adjacent tissues. In this work, we first construct a simple model of epithelial cells capable of passive CE in response to external forces. We adapt this framework to simulate CE from active anisotropic processes in three different modes: crawling, contraction, and capture. We develop an image analysis pipeline for analysis of morphogenetic changes in both live cells and simulated cells using a panel of mechanical and statistical approaches. Our results allow us to identify how each simulated mechanism uniquely contributes to tissue morphology and provide insight into how force transmission is coordinated. We construct a MEchanism Index (MEI) to quantify how similar live cells are to simulated passive and active cells undergoing CE. Applying these analyses to live cell data of Xenopus neural CE reveals features of both passive motion and active forces. Furthermore, we find spatial variation across the neural plate. We compare the inferred mechanisms in the frog midline to tissues undergoing CE in both the mouse and fly. We find that distinct active modes may have different prevalences depending on the model system. Our modeling framework allows us to gain insight from tissue timelapse images and assess the relative contribution of specific cellular mechanisms to observed tissue phenotypes. This approach can be used to guide further experimental inquiry into how mechanics influences the shaping of tissues and organs during development.
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Affiliation(s)
- Sommer Anjum
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Computational Modeling and Simulation Graduate Program, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | | - Rodrigo Fernandez-Gonzalez
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
- Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON, M5G 1M1, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada
| | - Ann Sutherland
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Lance Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Brauns F, Claussen NH, Lefebvre MF, Wieschaus EF, Shraiman BI. The geometric basis of epithelial convergent extension. eLife 2024; 13:RP95521. [PMID: 39699945 DOI: 10.7554/elife.95521] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2024] Open
Abstract
Shape changes of epithelia during animal development, such as convergent extension, are achieved through the concerted mechanical activity of individual cells. While much is known about the corresponding large-scale tissue flow and its genetic drivers, fundamental questions regarding local control of contractile activity on the cellular scale and its embryo-scale coordination remain open. To address these questions, we develop a quantitative, model-based analysis framework to relate cell geometry to local tension in recently obtained time-lapse imaging data of gastrulating Drosophila embryos. This analysis systematically decomposes cell shape changes and T1 rearrangements into internally driven, active, and externally driven, passive, contributions. Our analysis provides evidence that germ band extension is driven by active T1 processes that self-organize through positive feedback acting on tensions. More generally, our findings suggest that epithelial convergent extension results from the controlled transformation of internal force balance geometry which combines the effects of bottom-up local self-organization with the top-down, embryo-scale regulation by gene expression.
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Affiliation(s)
- Fridtjof Brauns
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, United States
| | - Nikolas H Claussen
- Department of Physics, University of California, Santa Barbara, Santa Barbara, United States
| | - Matthew F Lefebvre
- Department of Physics, University of California, Santa Barbara, Santa Barbara, United States
| | - Eric F Wieschaus
- Department of Molecular Biology, Princeton University, Princeton, United States
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Boris I Shraiman
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, United States
- Department of Physics, University of California, Santa Barbara, Santa Barbara, United States
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Brauns F, Claussen NH, Lefebvre MF, Wieschaus EF, Shraiman BI. The Geometric Basis of Epithelial Convergent Extension. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.30.542935. [PMID: 37398061 PMCID: PMC10312603 DOI: 10.1101/2023.05.30.542935] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Shape changes of epithelia during animal development, such as convergent extension, are achieved through concerted mechanical activity of individual cells. While much is known about the corresponding large scale tissue flow and its genetic drivers, fundamental questions regarding local control of contractile activity on cellular scale and its embryo-scale coordination remain open. To address these questions, we develop a quantitative, model-based analysis framework to relate cell geometry to local tension in recently obtained timelapse imaging data of gastrulating Drosophila embryos. This analysis provides a systematic decomposition of cell shape changes and T1-rearrangements into internally driven, active, and externally driven, passive, contributions. Our analysis provides evidence that germ band extension is driven by active T1 processes that self-organize through positive feedback acting on tensions. More generally, our findings suggest that epithelial convergent extension results from controlled transformation of internal force balance geometry which combines the effects of bottom-up local self-organization with the top-down, embryo-scale regulation by gene expression.
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Affiliation(s)
- Fridtjof Brauns
- Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Nikolas H. Claussen
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Matthew F. Lefebvre
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Eric F. Wieschaus
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA; The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Boris I. Shraiman
- Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
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Kraus Y, Osadchenko B, Kosevich I. Embryonic development of the moon jellyfish Aurelia aurita (Cnidaria, Scyphozoa): another variant on the theme of invagination. PeerJ 2022; 10:e13361. [PMID: 35607447 PMCID: PMC9123889 DOI: 10.7717/peerj.13361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 04/08/2022] [Indexed: 01/13/2023] Open
Abstract
Background Aurelia aurita (Scyphozoa, Cnidaria) is an emblematic species of the jellyfish. Currently, it is an emerging model of Evo-Devo for studying evolution and molecular regulation of metazoans' complex life cycle, early development, and cell differentiation. For Aurelia, the genome was sequenced, the molecular cascades involved in the life cycle transitions were characterized, and embryogenesis was studied on the level of gross morphology. As a reliable representative of the class Scyphozoa, Aurelia can be used for comparative analysis of embryonic development within Cnidaria and between Cnidaria and Bilateria. One of the intriguing questions that can be posed is whether the invagination occurring during gastrulation of different cnidarians relies on the same cellular mechanisms. To answer this question, a detailed study of the cellular mechanisms underlying the early development of Aurelia is required. Methods We studied the embryogenesis of A. aurita using the modern methods of light microscopy, immunocytochemistry, confocal laser microscopy, scanning and transmission electron microscopy. Results In this article, we report a comprehensive study of the early development of A. aurita from the White Sea population. We described in detail the embryonic development of A. aurita from early cleavage up to the planula larva. We focused mainly on the cell morphogenetic movements underlying gastrulation. The dynamics of cell shape changes and cell behavior during invagination of the archenteron (future endoderm) were characterized. That allowed comparing the gastrulation by invagination in two cnidarian species-scyphozoan A. aurita and anthozoan Nematostella vectensis. We described the successive stages of blastopore closure and found that segregation of the germ layers in A. aurita is linked to the 'healing' of the blastopore lip. We followed the developmental origin of the planula body parts and characterized the planula cells' ultrastructure. We also found that the planula endoderm consists of three morphologically distinct compartments along the oral-aboral axis. Conclusions Epithelial invagination is a fundamental morphogenetic movement that is believed as highly conserved across metazoans. Our data on the cell shaping and behaviours driving invagination in A. aurita contribute to understanding of morphologically similar morphogenesis in different animals. By comparative analysis, we clearly show that invagination may differ at the cellular level between cnidarian species belonging to different classes (Anthozoa and Scyphozoa). The number of cells involved in invagination, the dynamics of the shape of the archenteron cells, the stage of epithelial-mesenchymal transition that these cells can reach, and the fate of blastopore lip cells may vary greatly between species. These results help to gain insight into the evolution of morphogenesis within the Cnidaria and within Metazoa in general.
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Affiliation(s)
- Yulia Kraus
- Department of Evolutionary Biology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
- Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, Moscow, Russia
| | - Boris Osadchenko
- Department of Invertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Igor Kosevich
- Department of Invertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
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Composite morphogenesis during embryo development. Semin Cell Dev Biol 2021; 120:119-132. [PMID: 34172395 DOI: 10.1016/j.semcdb.2021.06.007] [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: 03/24/2021] [Revised: 05/23/2021] [Accepted: 06/13/2021] [Indexed: 11/21/2022]
Abstract
Morphogenesis drives the formation of functional living shapes. Gene expression patterns and signaling pathways define the body plans of the animal and control the morphogenetic processes shaping the embryonic tissues. During embryogenesis, a tissue can undergo composite morphogenesis resulting from multiple concomitant shape changes. While previous studies have unraveled the mechanisms that drive simple morphogenetic processes, how a tissue can undergo multiple and simultaneous changes in shape is still not known and not much explored. In this chapter, we focus on the process of concomitant tissue folding and extension that is vital for the animal since it is key for embryo gastrulation and neurulation. Recent pioneering studies focus on this problem highlighting the roles of different spatially coordinated cell mechanisms or of the synergy between different patterns of gene expression to drive composite morphogenesis.
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Mechanical induction and competence in epithelial morphogenesis. Curr Opin Genet Dev 2020; 63:36-44. [DOI: 10.1016/j.gde.2020.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 02/27/2020] [Accepted: 03/01/2020] [Indexed: 11/18/2022]
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Ettensohn CA. The gene regulatory control of sea urchin gastrulation. Mech Dev 2020; 162:103599. [PMID: 32119908 DOI: 10.1016/j.mod.2020.103599] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/21/2020] [Accepted: 02/24/2020] [Indexed: 02/07/2023]
Abstract
The cell behaviors associated with gastrulation in sea urchins have been well described. More recently, considerable progress has been made in elucidating gene regulatory networks (GRNs) that underlie the specification of early embryonic territories in this experimental model. This review integrates information from these two avenues of work. I discuss the principal cell movements that take place during sea urchin gastrulation, with an emphasis on molecular effectors of the movements, and summarize our current understanding of the gene regulatory circuitry upstream of those effectors. A case is made that GRN biology can provide a causal explanation of gastrulation, although additional analysis is needed at several levels of biological organization in order to provide a deeper understanding of this complex morphogenetic process.
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Affiliation(s)
- Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Ave., Pittsburgh, PA 15213, USA.
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Sutherland A, Keller R, Lesko A. Convergent extension in mammalian morphogenesis. Semin Cell Dev Biol 2019; 100:199-211. [PMID: 31734039 DOI: 10.1016/j.semcdb.2019.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/01/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022]
Abstract
Convergent extension is a fundamental morphogenetic process that underlies not only the generation of the elongated vertebrate body plan from the initially radially symmetrical embryo, but also the specific shape changes characteristic of many individual tissues. These tissue shape changes are the result of specific cell behaviors, coordinated in time and space, and affected by the physical properties of the tissue. While mediolateral cell intercalation is the classic cellular mechanism for producing tissue convergence and extension, other cell behaviors can also provide similar tissue-scale distortions or can modulate the effects of mediolateral cell intercalation to sculpt a specific shape. Regulation of regional tissue morphogenesis through planar polarization of the variety of underlying cell behaviors is well-recognized, but as yet is not well understood at the molecular level. Here, we review recent advances in understanding the cellular basis for convergence and extension and its regulation.
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Affiliation(s)
- Ann Sutherland
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA, 22908, USA.
| | - Raymond Keller
- Department of Biology, University of Virginia, Charlottesville, VA, 22903, USA.
| | - Alyssa Lesko
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA, 22908, USA.
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Affiliation(s)
- Dennis E. Discher
- Molecular & Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104,*Address correspondence to: Dennis E. Discher ()
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