1
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Gannavarapu A, Arzash S, Muntz I, Shivers JL, Klianeva AM, Koenderink GH, MacKintosh FC. Effects of local incompressibility on the rheology of composite biopolymer networks. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:36. [PMID: 38802588 DOI: 10.1140/epje/s10189-024-00422-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 04/08/2024] [Indexed: 05/29/2024]
Abstract
Fibrous networks such as collagen are common in biological systems. Recent theoretical and experimental efforts have shed light on the mechanics of single component networks. Most real biopolymer networks, however, are composites made of elements with different rigidity. For instance, the extracellular matrix in mammalian tissues consists of stiff collagen fibers in a background matrix of flexible polymers such as hyaluronic acid (HA). The interplay between different biopolymer components in such composite networks remains unclear. In this work, we use 2D coarse-grained models to study the nonlinear strain-stiffening behavior of composites. We introduce a local volume constraint to model the incompressibility of HA. We also perform rheology experiments on composites of collagen with HA. Theoretically and experimentally, we demonstrate that the linear shear modulus of composite networks can be increased by approximately an order of magnitude above the corresponding moduli of the pure components. Our model shows that this synergistic effect can be understood in terms of the local incompressibility of HA, which acts to suppress density fluctuations of the collagen matrix with which it is entangled.
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Affiliation(s)
- Anupama Gannavarapu
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, 77005, TX, USA.
- Center for Theoretical Biological Physics, Rice University, Houston, 77005, TX, USA.
| | - Sadjad Arzash
- Department of Physics, Syracuse University, Syracuse, 13244, NY, USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, 16802, PA, USA
| | - Iain Muntz
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Jordan L Shivers
- Department of Chemistry, University of Chicago, Chicago, 60637, IL, USA
- James Franck Institute, University of Chicago, Chicago, 60637, IL, USA
| | - Anna-Maria Klianeva
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
| | - Fred C MacKintosh
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, 77005, TX, USA.
- Center for Theoretical Biological Physics, Rice University, Houston, 77005, TX, USA.
- Department of Chemistry, Rice University, Houston, 77005, TX, USA.
- Department of Physics and Astronomy, Rice University, Houston, 77005, TX, USA.
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2
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Boutillon A, Banavar SP, Campàs O. Conserved physical mechanisms of cell and tissue elongation. Development 2024; 151:dev202687. [PMID: 38767601 PMCID: PMC11190436 DOI: 10.1242/dev.202687] [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] [Indexed: 05/22/2024]
Abstract
Living organisms have the ability to self-shape into complex structures appropriate for their function. The genetic and molecular mechanisms that enable cells to do this have been extensively studied in several model and non-model organisms. In contrast, the physical mechanisms that shape cells and tissues have only recently started to emerge, in part thanks to new quantitative in vivo measurements of the physical quantities guiding morphogenesis. These data, combined with indirect inferences of physical characteristics, are starting to reveal similarities in the physical mechanisms underlying morphogenesis across different organisms. Here, we review how physics contributes to shape cells and tissues in a simple, yet ubiquitous, morphogenetic transformation: elongation. Drawing from observed similarities across species, we propose the existence of conserved physical mechanisms of morphogenesis.
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Affiliation(s)
- Arthur Boutillon
- Cluster of Excellence Physics of Life, TU Dresden, 01062 Dresden, Germany
| | - Samhita P. Banavar
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08540, USA
| | - Otger Campàs
- Cluster of Excellence Physics of Life, TU Dresden, 01062 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
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3
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Coraggio F, Bhushan M, Roumeliotis S, Caroti F, Bevilacqua C, Prevedel R, Rapti G. Age-progressive interplay of HSP-proteostasis, ECM-cell junctions and biomechanics ensures C. elegans astroglial architecture. Nat Commun 2024; 15:2861. [PMID: 38570505 PMCID: PMC10991496 DOI: 10.1038/s41467-024-46827-2] [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: 01/08/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024] Open
Abstract
Tissue integrity is sensitive to temperature, tension, age, and is sustained throughout life by adaptive cell-autonomous or extrinsic mechanisms. Safeguarding the remarkably-complex architectures of neurons and glia ensures age-dependent integrity of functional circuits. Here, we report mechanisms sustaining the integrity of C. elegans CEPsh astrocyte-like glia. We combine large-scale genetics with manipulation of genes, cells, and their environment, quantitative imaging of cellular/ subcellular features, tissue material properties and extracellular matrix (ECM). We identify mutants with age-progressive, environment-dependent defects in glial architecture, consequent disruption of neuronal architecture, and abnormal aging. Functional loss of epithelial Hsp70/Hsc70-cochaperone BAG2 causes ECM disruption, altered tissue biomechanics, and hypersensitivity of glia to environmental temperature and mechanics. Glial-cell junctions ensure epithelia-ECM-CEPsh glia association. Modifying glial junctions or ECM mechanics safeguards glial integrity against disrupted BAG2-proteostasis. Overall, we present a finely-regulated interplay of proteostasis-ECM and cell junctions with conserved components that ensures age-progressive robustness of glial architecture.
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Affiliation(s)
- Francesca Coraggio
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Mahak Bhushan
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Spyridon Roumeliotis
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Francesca Caroti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carlo Bevilacqua
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Robert Prevedel
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany
- German Center for Lung Research (DZL), Heidelberg, Germany
| | - Georgia Rapti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy.
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany.
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4
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Manicka S, Pai VP, Levin M. Information integration during bioelectric regulation of morphogenesis of the embryonic frog brain. iScience 2023; 26:108398. [PMID: 38034358 PMCID: PMC10687303 DOI: 10.1016/j.isci.2023.108398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 07/18/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023] Open
Abstract
Spatiotemporal patterns of cellular resting potential regulate several aspects of development. One key aspect of the bioelectric code is that transcriptional and morphogenetic states are determined not by local, single-cell, voltage levels but by specific distributions of voltage across cell sheets. We constructed and analyzed a minimal dynamical model of collective gene expression in cells based on inputs of multicellular voltage patterns. Causal integration analysis revealed a higher-order mechanism by which information about the voltage pattern was spatiotemporally integrated into gene activity, as well as a division of labor among and between the bioelectric and genetic components. We tested and confirmed predictions of this model in a system in which bioelectric control of morphogenesis regulates gene expression and organogenesis: the embryonic brain of the frog Xenopus laevis. This study demonstrates that machine learning and computational integration approaches can advance our understanding of the information-processing underlying morphogenetic decision-making, with a potential for other applications in developmental biology and regenerative medicine.
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Affiliation(s)
- Santosh Manicka
- Allen Discovery Center at Tufts University, Medford, MA 02155, USA
| | - Vaibhav P. Pai
- Allen Discovery Center at Tufts University, Medford, MA 02155, USA
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA 02155, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
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5
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Anjum S, Turner L, Atieh Y, Eisenhoffer GT, Davidson L. Assessing mechanical agency during apical apoptotic cell extrusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564227. [PMID: 37961593 PMCID: PMC10634859 DOI: 10.1101/2023.10.26.564227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Epithelial tissues maintain homeostasis through the continual addition and removal of cells. Homeostasis is necessary for epithelia to maintain barrier function and prevent the accumulation of defective cells. Unfit, excess, and dying cells can be removed from epithelia by the process of extrusion. Controlled cell death and extrusion in the epithelium of the larval zebrafish tail fin coincides with oscillation of cell area, both in the extruding cell and its neighbors. Both cell-autonomous and non-autonomous factors have been proposed to contribute to extrusion but have been challenging to test by experimental approaches. Here we develop a dynamic cell-based biophysical model that recapitulates the process of oscillatory cell extrusion to test and compare the relative contributions of these factors. Our model incorporates the mechanical properties of individual epithelial cells in a two-dimensional simulation as repelling active particles. The area of cells destined to extrude oscillates with varying durations or amplitudes, decreasing their mechanical contribution to the epithelium and surrendering their space to surrounding cells. Quantitative variations in cell shape and size during extrusion are visualized by a hybrid weighted Voronoi tessellation technique that renders individual cell mechanical properties directly into an epithelial sheet. To explore the role of autonomous and non-autonomous mechanics, we vary the biophysical properties and behaviors of extruding cells and neighbors such as the period and amplitude of repulsive forces, cell density, and tissue viscosity. Our data suggest that cell autonomous processes are major contributors to the dynamics of extrusion, with the mechanical microenvironment providing a less pronounced contribution. Our computational model based on in vivo data serves as a tool to provide insights into the cellular dynamics and localized changes in mechanics that promote elimination of unwanted cells from epithelia during homeostatic tissue maintenance.
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Affiliation(s)
- Sommer Anjum
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Llaran Turner
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Genetics and Epigenetics Graduate Program, University of Texas MD Anderson Cancer Center, UTHealth Houston Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Youmna Atieh
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - George T. Eisenhoffer
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Genetics and Epigenetics Graduate Program, University of Texas MD Anderson Cancer Center, UTHealth Houston Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Lance Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
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6
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Handler C, Scarcelli G, Zhang J. Time-lapse mechanical imaging of neural tube closure in live embryo using Brillouin microscopy. Sci Rep 2023; 13:263. [PMID: 36609620 PMCID: PMC9823106 DOI: 10.1038/s41598-023-27456-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 01/02/2023] [Indexed: 01/09/2023] Open
Abstract
Neural tube closure (NTC) is a complex process of embryonic development involving molecular, cellular, and biomechanical mechanisms. While the genetic factors and biochemical signaling have been extensively investigated, the role of tissue biomechanics remains mostly unexplored due to the lack of tools. Here, we developed an optical modality that can conduct time-lapse mechanical imaging of neural plate tissue as the embryo is experiencing neurulation. This technique is based on the combination of a confocal Brillouin microscope and a modified ex ovo culturing of chick embryo with an on-stage incubator. With this technique, for the first time, we captured the mechanical evolution of the neural plate tissue with live embryos. Specifically, we observed the continuous increase in tissue modulus of the neural plate during NTC for ex ovo cultured embryos, which is consistent with the data of in ovo culture as well as previous studies. Beyond that, we found that the increase in tissue modulus was highly correlated with the tissue thickening and bending. We foresee this non-contact and label-free technique opening new opportunities to understand the biomechanical mechanisms in embryonic development.
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Affiliation(s)
- Chenchen Handler
- grid.164295.d0000 0001 0941 7177Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742 USA
| | - Giuliano Scarcelli
- grid.164295.d0000 0001 0941 7177Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742 USA
| | - Jitao Zhang
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, 48201, USA.
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7
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Hazan H, Levin M. Exploring the Behavior of Bioelectric Circuits Using Evolution Heuristic Search. Bioelectricity 2022. [DOI: 10.1089/bioe.2022.0033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Hananel Hazan
- Allen Discovery Center at Tufts University, Medford, Massachusetts, USA
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA
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8
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Moss JJ, Wirth M, Tooze SA, Lane JD, Hammond CL. Autophagy coordinates chondrocyte development and early joint formation in zebrafish. FASEB J 2021; 35:e22002. [PMID: 34708458 DOI: 10.1096/fj.202101167r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 12/16/2022]
Abstract
Autophagy is a catabolic process responsible for the removal of waste and damaged cellular components by lysosomal degradation. It plays a key role in fundamental cell processes, including ER stress mitigation, control of cell metabolism, and cell differentiation and proliferation, all of which are essential for cartilage cell (chondrocyte) development and survival, and for the formation of cartilage. Correspondingly, autophagy dysregulation has been implicated in several skeletal disorders such as osteoarthritis and osteoporosis. To test the requirement for autophagy during skeletal development in zebrafish, we generated an atg13 CRISPR knockout zebrafish line. This line showed a complete loss of atg13 expression, and restricted autophagic activity in vivo. In the absence of autophagy, chondrocyte maturation was accelerated, with chondrocytes exhibiting signs of premature hypertrophy. Focussing on the jaw element, autophagy disruption affected joint articulation causing restricted mouth opening. This gross behavioural phenotype corresponded with a failure to thrive, and death in homozygote atg13 nulls within 17 days. Taken together, our results are consistent with autophagy contributing to the timely regulation of chondrocyte maturation and for extracellular matrix formation.
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Affiliation(s)
- Joanna J Moss
- School of Biochemistry, University of Bristol, Bristol, UK.,School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Martina Wirth
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, UK
| | - Sharon A Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, UK
| | - Jon D Lane
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Chrissy L Hammond
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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9
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Marconi M, Wabnik K. Shaping the Organ: A Biologist Guide to Quantitative Models of Plant Morphogenesis. FRONTIERS IN PLANT SCIENCE 2021; 12:746183. [PMID: 34675952 PMCID: PMC8523991 DOI: 10.3389/fpls.2021.746183] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/09/2021] [Indexed: 06/13/2023]
Abstract
Organ morphogenesis is the process of shape acquisition initiated with a small reservoir of undifferentiated cells. In plants, morphogenesis is a complex endeavor that comprises a large number of interacting elements, including mechanical stimuli, biochemical signaling, and genetic prerequisites. Because of the large body of data being produced by modern laboratories, solving this complexity requires the application of computational techniques and analyses. In the last two decades, computational models combined with wet-lab experiments have advanced our understanding of plant organ morphogenesis. Here, we provide a comprehensive review of the most important achievements in the field of computational plant morphodynamics. We present a brief history from the earliest attempts to describe plant forms using algorithmic pattern generation to the evolution of quantitative cell-based models fueled by increasing computational power. We then provide an overview of the most common types of "digital plant" paradigms, and demonstrate how models benefit from diverse techniques used to describe cell growth mechanics. Finally, we highlight the development of computational frameworks designed to resolve organ shape complexity through integration of mechanical, biochemical, and genetic cues into a quantitative standardized and user-friendly environment.
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Affiliation(s)
| | - Krzysztof Wabnik
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Pozuelo de Alarcón (Madrid), Spain
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10
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Manicka S, Levin M. The Cognitive Lens: a primer on conceptual tools for analysing information processing in developmental and regenerative morphogenesis. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180369. [PMID: 31006373 PMCID: PMC6553590 DOI: 10.1098/rstb.2018.0369] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2018] [Indexed: 12/31/2022] Open
Abstract
Brains exhibit plasticity, multi-scale integration of information, computation and memory, having evolved by specialization of non-neural cells that already possessed many of the same molecular components and functions. The emerging field of basal cognition provides many examples of decision-making throughout a wide range of non-neural systems. How can biological information processing across scales of size and complexity be quantitatively characterized and exploited in biomedical settings? We use pattern regulation as a context in which to introduce the Cognitive Lens-a strategy using well-established concepts from cognitive and computer science to complement mechanistic investigation in biology. To facilitate the assimilation and application of these approaches across biology, we review tools from various quantitative disciplines, including dynamical systems, information theory and least-action principles. We propose that these tools can be extended beyond neural settings to predict and control systems-level outcomes, and to understand biological patterning as a form of primitive cognition. We hypothesize that a cognitive-level information-processing view of the functions of living systems can complement reductive perspectives, improving efficient top-down control of organism-level outcomes. Exploration of the deep parallels across diverse quantitative paradigms will drive integrative advances in evolutionary biology, regenerative medicine, synthetic bioengineering, cognitive neuroscience and artificial intelligence. This article is part of the theme issue 'Liquid brains, solid brains: How distributed cognitive architectures process information'.
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Affiliation(s)
| | - Michael Levin
- Allen Discovery Center, Tufts University, Medford, MA 02155, USA
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11
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Ben Amar M, Nassoy P, LeGoff L. Physics of growing biological tissues: the complex cross-talk between cell activity, growth and resistance. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180070. [PMID: 30879412 PMCID: PMC6452036 DOI: 10.1098/rsta.2018.0070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/06/2019] [Indexed: 05/04/2023]
Abstract
For many organisms, shapes emerge from growth, which generates stresses, which in turn can feedback on growth. In this review, theoretical methods to analyse various aspects of morphogenesis are discussed with the aim to determine the most adapted method for tissue mechanics. We discuss the need to work at scales intermediate between cells and tissues and emphasize the use of finite elasticity for this. We detail the application of these ideas to four systems: active cells embedded in tissues, brain cortical convolutions, the cortex of Caenorhabditis elegans during elongation and finally the proliferation of epithelia on extracellular matrix. Numerical models well adapted to inhomogeneities are also presented. This article is part of the theme issue 'Rivlin's legacy in continuum mechanics and applied mathematics'.
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Affiliation(s)
- Martine Ben Amar
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, 24 rue Lhomond, 75005 Paris, France
- Faculté de médecine, Institut Universitaire de Cancérologie, Sorbonne Université, 91 Bd de l'Hôpital, 75013 Paris, France
| | - Pierre Nassoy
- Laboratoire Photonique Numérique et Nanosciences, CNRS UMR 5298, Université de Bordeaux and Institut d'Optique F-33400 Talence, France
| | - Loic LeGoff
- CNRS, Centrale Marseille, Institut Fresnel, Aix Marseille Univ, Marseille, France
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12
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Love AM, Prince DJ, Jessen JR. Vangl2-dependent regulation of membrane protrusions and directed migration requires a fibronectin extracellular matrix. Development 2018; 145:dev.165472. [PMID: 30327324 DOI: 10.1242/dev.165472] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 10/08/2018] [Indexed: 01/30/2023]
Abstract
During zebrafish gastrulation the planar cell polarity (PCP) protein Vang-like 2 (Vangl2) regulates the polarization of cells that are engaged in directed migration. However, it is unclear whether Vangl2 influences membrane-protrusive activities in migrating gastrula cells and whether these processes require the fibronectin extracellular matrix. Here, we report that Vangl2 modulates the formation and polarization of actin-rich filopodia-like and large lamellipodia-like protrusions in ectodermal cells. By contrast, disrupted Glypican4/PCP signaling affects protrusion polarity but not protrusion number or directed migration. Analysis of fluorescent fusion protein expression suggests that there is widespread Vangl2 symmetry in migrating cells, but there is enrichment at membrane domains that are developing large protrusions compared with non-protrusive domains. We show that the fibronectin extracellular matrix is essential for cell-surface Vangl2 expression, membrane-protrusive activity and directed migration. Manipulation of fibronectin protein levels rescues protrusion and directed migration phenotypes in vangl2 mutant embryos, but it is not sufficient to restore either PCP, or convergence and extension movements. Together, our findings identify distinct roles for Vangl2 and Glypican4/PCP signaling during membrane protrusion formation and demonstrate that cell-matrix interactions underlie Vangl2-dependent regulation of protrusive activities in migrating gastrula cells.
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Affiliation(s)
- Anna M Love
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA
| | - Dianna J Prince
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA
| | - Jason R Jessen
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA
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13
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Zhang J, Raghunathan R, Rippy J, Wu C, Finnell RH, Larin KV, Scarcelli G. Tissue biomechanics during cranial neural tube closure measured by Brillouin microscopy and optical coherence tomography. Birth Defects Res 2018; 111:991-998. [PMID: 30239173 DOI: 10.1002/bdr2.1389] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/03/2018] [Accepted: 08/02/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Embryonic development involves the interplay of driving forces that shape the tissue and the mechanical resistance that the tissue offers in response. While increasing evidence has suggested the crucial role of physical mechanisms underlying embryo development, tissue biomechanics is not well understood because of the lack of techniques that can quantify the stiffness of tissue in situ with 3D high-resolution and in a noncontact manner. METHODS We used two all-optical techniques, optical coherence tomography (OCT) and Brillouin microscopy, to map the longitudinal modulus of the tissue from mouse embryos in situ. RESULTS We acquired 2D mechanical maps of the neural tube region of embryos at embryonic day (E) 8.5 (n = 2) and E9.5 (n = 2) with submicron spatial resolution. We found the modulus of tissue varied distinctly within the neural tube region of the same embryo and between embryos at different development stages, suggesting our technique has enough sensitivity and spatial resolution to monitor the tissue mechanics during embryonic development in a noncontact and noninvasive manner. CONCLUSIONS We demonstrated the capability of OCT-guided Brillouin microscopy to quantify tissue longitudinal modulus of mouse embryos in situ, and observed distinct change in the modulus during the closure of cranial neural tube. Although this preliminary work cannot provide definitive conclusions on biomechanics of neural tube closure yet as a result of the limited number of samples, it provides an approach of quantifying the tissue mechanics during embryo development in situ, thus could be helpful in investigating the role of tissue biomechanics in the regulation of embryonic development. Our next study involving more embryo samples will investigate systematic changes in tissue mechanics during embryonic development.
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Affiliation(s)
- Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland, Maryland
| | - Raksha Raghunathan
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Justin Rippy
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Chen Wu
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Richard H Finnell
- Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas.,Departments of Molecular and Cellular Biology and Medicine, Baylor College of Medicine, Houston, Texas.,Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia
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14
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Xie Y, Miao H, Blankenship JT. Membrane trafficking in morphogenesis and planar polarity. Traffic 2018; 19:10.1111/tra.12580. [PMID: 29756260 PMCID: PMC6235730 DOI: 10.1111/tra.12580] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/01/2018] [Accepted: 05/02/2018] [Indexed: 12/31/2022]
Abstract
Our understanding of how membrane trafficking pathways function to direct morphogenetic movements and the planar polarization of developing tissues is a new and emerging field. While a central focus of developmental biology has been on how protein asymmetries and cytoskeletal force generation direct cell shaping, the role of membrane trafficking in these processes has been less clear. Here, we review recent advances in Drosophila and vertebrate systems in our understanding of how trafficking events are coordinated with planar cytoskeletal function to drive lasting changes in cell and tissue topologies. We additionally explore the function of trafficking pathways in guiding the complex interactions that initiate and maintain core PCP (planar cell polarity) asymmetries and drive the generation of systematically oriented cellular projections during development.
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Affiliation(s)
- Yi Xie
- Department of Biological Sciences, University of Denver, Denver, CO
80208, USA
| | - Hui Miao
- Department of Biological Sciences, University of Denver, Denver, CO
80208, USA
| | - J. Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO
80208, USA
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15
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Mosaffa P, Rodríguez-Ferran A, Muñoz JJ. Hybrid cell-centred/vertex model for multicellular systems with equilibrium-preserving remodelling. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2928. [PMID: 28898926 DOI: 10.1002/cnm.2928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
We present a hybrid cell-centred/vertex model for mechanically simulating planar cellular monolayers undergoing cell reorganisation. Cell centres are represented by a triangular nodal network, while the cell boundaries are formed by an associated vertex network. The two networks are coupled through a kinematic constraint which we allow to relax progressively. Special attention is paid to the change of cell-cell connectivity due to cell reorganisation or remodelling events. We handle these situations by using a variable resting length and applying an Equilibrium-Preserving Mapping on the new connectivity, which computes a new set of resting lengths that preserve nodal and vertex equilibrium. We illustrate the properties of the model by simulating monolayers subjected to imposed extension and during a wound healing process. The evolution of forces and the Equilibrium-Preserving Mapping are analysed during the remodelling events. As a by-product, the proposed technique enables to recover fully vertex or fully cell-centred models in a seamless manner by modifying a numerical parameter of the model.
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Affiliation(s)
- Payman Mosaffa
- Laboratori de Càlcul Numèric (LaCàN), Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona, Spain
| | - Antonio Rodríguez-Ferran
- Laboratori de Càlcul Numèric (LaCàN), Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona, Spain
| | - José J Muñoz
- Laboratori de Càlcul Numèric (LaCàN), Universitat Politècnica de Catalunya-Barcelona Tech, Barcelona, Spain
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16
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Logvenkov SA, Stein AA. A Mathematical Model of Spatial Self-Organization in a Mechanically Active Cellular Medium. Biophysics (Nagoya-shi) 2018. [DOI: 10.1134/s0006350917060136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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Levin M, Martyniuk CJ. The bioelectric code: An ancient computational medium for dynamic control of growth and form. Biosystems 2018; 164:76-93. [PMID: 28855098 PMCID: PMC10464596 DOI: 10.1016/j.biosystems.2017.08.009] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/20/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022]
Abstract
What determines large-scale anatomy? DNA does not directly specify geometrical arrangements of tissues and organs, and a process of encoding and decoding for morphogenesis is required. Moreover, many species can regenerate and remodel their structure despite drastic injury. The ability to obtain the correct target morphology from a diversity of initial conditions reveals that the morphogenetic code implements a rich system of pattern-homeostatic processes. Here, we describe an important mechanism by which cellular networks implement pattern regulation and plasticity: bioelectricity. All cells, not only nerves and muscles, produce and sense electrical signals; in vivo, these processes form bioelectric circuits that harness individual cell behaviors toward specific anatomical endpoints. We review emerging progress in reading and re-writing anatomical information encoded in bioelectrical states, and discuss the approaches to this problem from the perspectives of information theory, dynamical systems, and computational neuroscience. Cracking the bioelectric code will enable much-improved control over biological patterning, advancing basic evolutionary developmental biology as well as enabling numerous applications in regenerative medicine and synthetic bioengineering.
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Affiliation(s)
- Michael Levin
- Allen Discovery Center at Tufts University, Biology Department, Tufts University, 200 Boston Avenue, Suite 4600 Medford, MA 02155, USA.
| | - Christopher J Martyniuk
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida Genetics Institute, Interdisciplinary Program in Biomedical Sciences Neuroscience, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
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18
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Fletcher AG, Cooper F, Baker RE. Mechanocellular models of epithelial morphogenesis. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2015.0519. [PMID: 28348253 DOI: 10.1098/rstb.2015.0519] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2016] [Indexed: 01/13/2023] Open
Abstract
Embryonic epithelia achieve complex morphogenetic movements, including in-plane reshaping, bending and folding, through the coordinated action and rearrangement of individual cells. Technical advances in molecular and live-imaging studies of epithelial dynamics provide a very real opportunity to understand how cell-level processes facilitate these large-scale tissue rearrangements. However, the large datasets that we are now able to generate require careful interpretation. In combination with experimental approaches, computational modelling allows us to challenge and refine our current understanding of epithelial morphogenesis and to explore experimentally intractable questions. To this end, a variety of cell-based modelling approaches have been developed to describe cell-cell mechanical interactions, ranging from vertex and 'finite-element' models that approximate each cell geometrically by a polygon representing the cell's membrane, to immersed boundary and subcellular element models that allow for more arbitrary cell shapes. Here, we review how these models have been used to provide insights into epithelial morphogenesis and describe how such models could help future efforts to decipher the forces and mechanical and biochemical feedbacks that guide cell and tissue-level behaviour. In addition, we discuss current challenges associated with using computational models of morphogenetic processes in a quantitative and predictive way.This article is part of the themed issue 'Systems morphodynamics: understanding the development of tissue hardware'.
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Affiliation(s)
- Alexander G Fletcher
- School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK .,Bateson Centre, University of Sheffield, Sheffield S10 2TN, UK
| | - Fergus Cooper
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
| | - Ruth E Baker
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
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19
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Suzuki T, Morishita Y. A quantitative approach to understanding vertebrate limb morphogenesis at the macroscopic tissue level. Curr Opin Genet Dev 2017; 45:108-114. [PMID: 28502890 DOI: 10.1016/j.gde.2017.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/13/2017] [Accepted: 04/13/2017] [Indexed: 02/01/2023]
Abstract
To understand organ morphogenetic mechanisms, it is essential to clarify how spatiotemporally-regulated molecular/cellular dynamics causes physical tissue deformation. In the case of vertebrate limb development, while some of the genes and oriented cell behaviors underlying morphogenesis have been revealed, tissue deformation dynamics remains incompletely understood. We here introduce our recent work on the reconstruction of tissue deformation dynamics in chick limb development from cell lineage tracing data. This analysis has revealed globally-aligned anisotropic tissue deformation along the proximo-distal axis not only in the distal region but also in the whole limb bud. This result points to a need, as a future challenge, to find oriented molecular/cellular behaviors for realizing the observed anisotropic tissue deformation in both proximal and distal regions, which will lead to systems understanding of limb morphogenesis.
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Affiliation(s)
- Takayuki Suzuki
- Division of Biological Science, Graduate School of Science, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Yoshihiro Morishita
- Laboratory for Developmental Morphogeometry, RIKEN Quantitative Biology Center, Kobe 650-0047, Japan.
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20
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D. S. V, L. A. D. Mechanics of neurulation: From classical to current perspectives on the physical mechanics that shape, fold, and form the neural tube. Birth Defects Res 2017; 109:153-168. [PMID: 27620928 PMCID: PMC9972508 DOI: 10.1002/bdra.23557] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Neural tube defects arise from mechanical failures in the process of neurulation. At the most fundamental level, formation of the neural tube relies on coordinated, complex tissue movements that mechanically transform the flat neural epithelium into a lumenized epithelial tube (Davidson, 2012). The nature of this mechanical transformation has mystified embryologists, geneticists, and clinicians for more than 100 years. Early embryologists pondered the physical mechanisms that guide this transformation. Detailed observations of cell and tissue movements as well as experimental embryological manipulations allowed researchers to generate and test elementary hypotheses of the intrinsic and extrinsic forces acting on the neural tissue. Current research has turned toward understanding the molecular mechanisms underlying neurulation. Genetic and molecular perturbation have identified a multitude of subcellular components that correlate with cell behaviors and tissue movements during neural tube formation. In this review, we focus on methods and conceptual frameworks that have been applied to the study of amphibian neurulation that can be used to determine how molecular and physical mechanisms are integrated and responsible for neurulation. We will describe how qualitative descriptions and quantitative measurements of strain, force generation, and tissue material properties as well as simulations can be used to understand how embryos use morphogenetic programs to drive neurulation. Birth Defects Research 109:153-168, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Vijayraghavan D. S.
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15260
| | - Davidson L. A.
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15260,Department of Developmental Biology, School of Medicine, University of Pittsburgh Pittsburgh, PA 15213,Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260
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21
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Logvenkov SA, Stein AA. Mathematical modeling of the stretching-induced elongation of the embryonic epithelium layer in the absence of an external load. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350915060184] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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22
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Brodland GW. How computational models can help unlock biological systems. Semin Cell Dev Biol 2015; 47-48:62-73. [DOI: 10.1016/j.semcdb.2015.07.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 06/15/2015] [Accepted: 07/01/2015] [Indexed: 01/04/2023]
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23
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Emmons-Bell M, Durant F, Hammelman J, Bessonov N, Volpert V, Morokuma J, Pinet K, Adams DS, Pietak A, Lobo D, Levin M. Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms. Int J Mol Sci 2015; 16:27865-96. [PMID: 26610482 PMCID: PMC4661923 DOI: 10.3390/ijms161126065] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 12/13/2022] Open
Abstract
The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol) can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina). We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts), and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies. Taken together, these data and analyses shed light on important physiological modifiers of morphological information in dictating species-specific shape, and reveal them to be a novel instructive input into head patterning in regenerating planaria.
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Affiliation(s)
- Maya Emmons-Bell
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Fallon Durant
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Jennifer Hammelman
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Nicholas Bessonov
- Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, Saint Petersburg 199178, Russia;
| | - Vitaly Volpert
- Institut Camille Jordan, UMR 5208 CNRS, University Lyon 1, Villeurbanne 69622, France;
| | - Junji Morokuma
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Kaylinnette Pinet
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Dany S. Adams
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | | | - Daniel Lobo
- Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA;
| | - Michael Levin
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
- Correspondence: ; Tel.: +1-617-627-6161; Fax: +1-617-627-6121
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24
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Mechanical Coupling between Endoderm Invagination and Axis Extension in Drosophila. PLoS Biol 2015; 13:e1002292. [PMID: 26544693 PMCID: PMC4636290 DOI: 10.1371/journal.pbio.1002292] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/02/2015] [Indexed: 11/25/2022] Open
Abstract
How genetic programs generate cell-intrinsic forces to shape embryos is actively studied, but less so how tissue-scale physical forces impact morphogenesis. Here we address the role of the latter during axis extension, using Drosophila germband extension (GBE) as a model. We found previously that cells elongate in the anteroposterior (AP) axis in the extending germband, suggesting that an extrinsic tensile force contributed to body axis extension. Here we further characterized the AP cell elongation patterns during GBE, by tracking cells and quantifying their apical cell deformation over time. AP cell elongation forms a gradient culminating at the posterior of the embryo, consistent with an AP-oriented tensile force propagating from there. To identify the morphogenetic movements that could be the source of this extrinsic force, we mapped gastrulation movements temporally using light sheet microscopy to image whole Drosophila embryos. We found that both mesoderm and endoderm invaginations are synchronous with the onset of GBE. The AP cell elongation gradient remains when mesoderm invagination is blocked but is abolished in the absence of endoderm invagination. This suggested that endoderm invagination is the source of the tensile force. We next looked for evidence of this force in a simplified system without polarized cell intercalation, in acellular embryos. Using Particle Image Velocimetry, we identify posteriorwards Myosin II flows towards the presumptive posterior endoderm, which still undergoes apical constriction in acellular embryos as in wildtype. We probed this posterior region using laser ablation and showed that tension is increased in the AP orientation, compared to dorsoventral orientation or to either orientations more anteriorly in the embryo. We propose that apical constriction leading to endoderm invagination is the source of the extrinsic force contributing to germband extension. This highlights the importance of physical interactions between tissues during morphogenesis. A study of the mechanism of axis extension in developing Drosophila embryos reveals that apical constriction leading to invagination of the posterior endoderm produces a tensile force that pulls the extending germband. Embryos change shape dramatically during development. The genetic programs that drive the active behavior of cells underlying these changes are well understood, but little is known about how movements of neighboring tissues influence the shaping of a given tissue. We address this question for the anteroposterior elongation of the body axis (germband) of Drosophila embryos. We had previously shown that during elongation, the germband cells stretch along the anteroposterior axis, in addition to undergoing active rearrangements; this suggested that extrinsic tensile forces might be at play. In the current study we find that the start of main body elongation is synchronous with the invagination of both the mesoderm and the endoderm. We analyze mutants and find that cell stretching disappears in embryos lacking endoderm invagination but remains in those lacking mesoderm invagination. We then measure tension using laser ablation in acellular embryos that lack active cell rearrangements in the germband but undergo the initial stages of endoderm invagination. We find that tension is higher in the anteroposterior direction close to the invaginating endoderm. Our results indicate that endoderm invagination generates a tensile force that is transmitted to the germband, and contributes to its elongation. This study reveals how tissues interact during embryo morphogenesis.
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25
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Himmelreich N, Kaufmann LT, Steinbeisser H, Körner C, Thiel C. Lack of phosphomannomutase 2 affects Xenopus laevis morphogenesis and the non-canonical Wnt5a/Ror2 signalling. J Inherit Metab Dis 2015; 38:1137-46. [PMID: 26141167 DOI: 10.1007/s10545-015-9874-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 01/22/2023]
Abstract
Reduced phosphomannomutase 2 activity in man leads to hypoglycosylation of glycoconjugates causing PMM2-CDG, the most common type of congenital disorders of glycosylation. Here we show that an antisense morpholino-mediated knockdown of the Xenopus laevis phosphomannomutase 2 gene provoked a general underglycosylation in frog embryos, which led to an altered phenotype and reduced glycosylation of Wnt5a as member of the non-canonical Wnt signalling. Loss of function experiments in hemi-sectioned embryos proved that due to the phosphomannomutase 2 knockdown expression of the Wnt5a/Ror2 target gene paraxial protocadherin was significantly decreased. Regarding the expression of paraxial protocadherin, a gain of function could only be achieved by injections of wnt5a and ror2 in dorsal neighbouring blastomeres, while a parallel injection of phosphomannomutase 2 morpholino led to a significant reduced level of expression. Our data show for the first time that a knockdown of phosphomannomutase 2 influences in vivo the non-canonical Wnt signalling during early embryogenesis.
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Affiliation(s)
- Nastassja Himmelreich
- Center for Child- and Adolescent Medicine and Center for Metabolic Diseases Heidelberg, Department I, Im Neuenheimer Feld 669, 69120, Heidelberg, Germany
| | - Lilian T Kaufmann
- Institute of Human Genetics, Division of Developmental Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120, Heidelberg, Germany
| | - Herbert Steinbeisser
- Institute of Human Genetics, Division of Developmental Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120, Heidelberg, Germany
| | - Christian Körner
- Center for Child- and Adolescent Medicine and Center for Metabolic Diseases Heidelberg, Department I, Im Neuenheimer Feld 669, 69120, Heidelberg, Germany
| | - Christian Thiel
- Center for Child- and Adolescent Medicine and Center for Metabolic Diseases Heidelberg, Department I, Im Neuenheimer Feld 669, 69120, Heidelberg, Germany.
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26
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Gredler ML, Seifert AW, Cohn MJ. Tissue-specific roles of Fgfr2 in development of the external genitalia. Development 2015; 142:2203-12. [PMID: 26081573 DOI: 10.1242/dev.119891] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Congenital anomalies frequently occur in organs that undergo tubulogenesis. Hypospadias is a urethral tube defect defined by mislocalized, oversized, or multiple openings of the penile urethra. Deletion of Fgfr2 or its ligand Fgf10 results in severe hypospadias in mice, in which the entire urethral plate is open along the ventral side of the penis. In the genital tubercle, the embryonic precursor of the penis and clitoris, Fgfr2 is expressed in two epithelial populations: the endodermally derived urethral epithelium and the ectodermally derived surface epithelium. Here, we investigate the tissue-specific roles of Fgfr2 in external genital development by generating conditional deletions of Fgfr2 in each of these cell types. Conditional deletion of Fgfr2 results in two distinct phenotypes: endodermal Fgfr2 deletion causes mild hypospadias and inhibits maturation of a complex urethral epithelium, whereas loss of ectodermal Fgfr2 results in severe hypospadias and absence of the ventral prepuce. Although these cell type-specific mutants exhibit distinctive genital anomalies, cellular analysis reveals that Fgfr2 regulates epithelial maturation and cell cycle progression in the urethral endoderm and in the surface ectoderm. The unexpected finding that ectodermal deletion of Fgfr2 results in the most severe hypospadias highlights a major role for Fgfr2 in the developing genital surface epithelium, where epithelial maturation is required for maintenance of a closed urethral tube. These results demonstrate that urethral tubulogenesis, prepuce morphogenesis, and sexually dimorphic patterning of the lower urethra are controlled by discrete regions of Fgfr2 activity.
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Affiliation(s)
- Marissa L Gredler
- Department of Biology, UF Genetics Institute, University of Florida, PO Box 103610, Gainesville, FL 32611, USA
| | - Ashley W Seifert
- Department of Biology, UF Genetics Institute, University of Florida, PO Box 103610, Gainesville, FL 32611, USA
| | - Martin J Cohn
- Department of Biology, UF Genetics Institute, University of Florida, PO Box 103610, Gainesville, FL 32611, USA Howard Hughes Medical Institute, Department of Molecular Genetics and Microbiology, University of Florida, PO Box 103610, Gainesville, FL 32611, USA
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27
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Perrone MC, Veldhuis JH, Brodland GW. Non-straight cell edges are important to invasion and engulfment as demonstrated by cell mechanics model. Biomech Model Mechanobiol 2015; 15:405-18. [PMID: 26148533 PMCID: PMC4792343 DOI: 10.1007/s10237-015-0697-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/23/2015] [Indexed: 11/28/2022]
Abstract
Computational models of cell–cell mechanical interactions typically simulate sorting and certain other motions well, but as demands on these models continue to grow, discrepancies between the cell shapes, contact angles and behaviours they predict and those that occur in real cells have come under increased scrutiny. To investigate whether these discrepancies are a direct result of the straight cell–cell edges generally assumed in these models, we developed a finite element model that approximates cell boundaries using polylines with an arbitrary number of segments. We then compared the predictions of otherwise identical polyline and monoline (straight-edge) models in a variety of scenarios, including annealing, single- and multi-cell engulfment, sorting, and two forms of mixing—invasion and checkerboard pattern formation. Keeping cell–cell edges straight influences cell motion, cell shape, contact angle, and boundary length, especially in cases where one cell type is pulled between or around cells of a different type, as in engulfment or invasion. These differences arise because monoline cells have restricted deformation modes. Polyline cells do not face these restrictions, and with as few as three segments per edge yielded realistic edge shapes and contact angle errors one-tenth of those produced by monoline models, making them considerably more suitable for situations where angles and shapes matter, such as validation of cellular force–inference techniques. The findings suggest that non-straight cell edges are important both in modelling and in nature.
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Affiliation(s)
- Matthew C Perrone
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Jim H Veldhuis
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - G Wayne Brodland
- Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
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28
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Gleghorn JP, Manivannan S, Nelson CM. Quantitative approaches to uncover physical mechanisms of tissue morphogenesis. Curr Opin Biotechnol 2013; 24:954-61. [PMID: 23647971 DOI: 10.1016/j.copbio.2013.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 04/12/2013] [Indexed: 12/30/2022]
Abstract
Morphogenesis, the creation of tissue and organ architecture, is a series of complex and dynamic processes driven by genetic programs, microenvironmental cues, and intercellular interactions. Elucidating the physical mechanisms that generate tissue form is key to understanding development, disease, and the strategies needed for regenerative therapies. Advancements in imaging technologies, genetic recombination techniques, laser ablation, and microfabricated tissue models have enabled quantitative descriptions of the cellular motions and tissue deformations and stresses with unprecedented temporal and spatial resolution. Using these data synergistically with increasingly more sophisticated physical, mathematical, and computational models will unveil the physical mechanisms that drive morphogenesis.
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Affiliation(s)
- Jason P Gleghorn
- Department of Chemical & Biological Engineering, Princeton University, Princeton, NJ 08544, United States
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29
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Shwartz Y, Farkas Z, Stern T, Aszódi A, Zelzer E. Muscle contraction controls skeletal morphogenesis through regulation of chondrocyte convergent extension. Dev Biol 2012; 370:154-63. [PMID: 22884393 DOI: 10.1016/j.ydbio.2012.07.026] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/23/2012] [Accepted: 07/25/2012] [Indexed: 02/01/2023]
Abstract
Convergent extension driven by mediolateral intercalation of chondrocytes is a key process that contributes to skeletal growth and morphogenesis. While progress has been made in deciphering the molecular mechanism that underlies this process, the involvement of mechanical load exerted by muscle contraction in its regulation has not been studied. Using the zebrafish as a model system, we found abnormal pharyngeal cartilage morphology in both chemically and genetically paralyzed embryos, demonstrating the importance of muscle contraction for zebrafish skeletal development. The shortening of skeletal elements was accompanied by prominent changes in cell morphology and organization. While in control the cells were elongated, chondrocytes in paralyzed zebrafish were smaller and exhibited a more rounded shape, confirmed by a reduction in their length-to-width ratio. The typical columnar organization of cells was affected too, as chondrocytes in various skeletal elements exhibited abnormal stacking patterns, indicating aberrant intercalation. Finally, we demonstrate impaired chondrocyte intercalation in growth plates of muscle-less Sp(d) mouse embryos, implying the evolutionary conservation of muscle force regulation of this essential morphogenetic process.Our findings provide a new perspective on the regulatory interaction between muscle contraction and skeletal morphogenesis by uncovering the role of muscle-induced mechanical loads in regulating chondrocyte intercalation in two different vertebrate models.
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Affiliation(s)
- Yulia Shwartz
- Department of Molecular Genetics, Weizmann Institute of Science, PO Box 26, Rehovot 76100, Israel
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Varner VD, Taber LA. On integrating experimental and theoretical models to determine physical mechanisms of morphogenesis. Biosystems 2012; 109:412-9. [PMID: 22612907 DOI: 10.1016/j.biosystems.2012.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/03/2012] [Accepted: 05/04/2012] [Indexed: 11/29/2022]
Abstract
Researchers in developmental biology are increasingly recognizing the value of theoretical models in studies of morphogenesis. However, creating and testing realistic quantitative models for morphogenetic processes can be an extremely challenging task. The focus of this paper is on models for the mechanics of morphogenesis. Models for these problems often must include large changes in geometry, leading to highly nonlinear problems with the possibility of multiple solutions that must be sorted out using experimental data. Here, we illustrate our approach to these problems using the specific example of head fold formation in the early chick embryo. The interplay between experimental and theoretical results is emphasized throughout, as the model is gradually refined. Some of the limitations inherent in theoretical/computational modeling of biological systems are also discussed.
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Affiliation(s)
- Victor D Varner
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA.
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31
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Active reinforcement of externally imposed folding in amphibians embryonic tissues. Mech Dev 2012; 129:51-60. [PMID: 22342666 DOI: 10.1016/j.mod.2012.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 11/20/2022]
Abstract
Although the folding of epithelial layers is one of the most common morphogenetic events, the underlying mechanisms of this process are still poorly understood. We aimed to determine whether an artificial bending of an embryonic cell sheet, which normally remains flat, is reinforced and stabilized by intrinsic cell transformations. We observed both reinforcement and stabilization in double explants of blastocoel roof tissue from Xenopus early gastrula embryos. The reinforcement of artificial bending occurred over the course of a few hours and was driven by the gradual apical constriction and radial elongation of previously compressed cells situated at the bending arch of the concave layer of explant. Apical constriction was associated with actomyosin contraction and endocytosis-mediated engulfing of the apical cell membranes. Cooperative apical constrictions of the concave layer of cells produced a tensile force that extended over the entire surface of the explant and correlated with apical contraction of the concave side cells. In the explants taken from the anterior regions of the embryo, this reinforcement was more stable and the bending better expressed than in those taken from suprablastoporal areas. The morphogenetic role of cell responses to the bending force is discussed.
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Miyajima H, Matsumoto T, Sakai T, Yamaguchi S, An SH, Abe M, Wakisaka S, Lee KY, Egusa H, Imazato S. Hydrogel-based biomimetic environment for in vitro modulation of branching morphogenesis. Biomaterials 2011; 32:6754-63. [PMID: 21683999 DOI: 10.1016/j.biomaterials.2011.05.072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 05/25/2011] [Indexed: 11/15/2022]
Abstract
The mechanical properties of the cellular microenvironment dramatically alter during tissue development and growth. Growing evidence suggests that physical microenvironments and mechanical stresses direct cell fate in developing tissue. However, how these physical cues affect the tissue morphogenesis remains a major unknown. We explain here that the physical properties of the cell and tissue microenvironment, biomimetically reproduced by using hydrogel, guide the tissue morphogenesis in the developmental submandibular gland (SMG). In particular, the softer gel enhances the bud expansion and cleft formation of SMG, whereas the stiffer gel attenuates them. These morphological changes in SMG tissue are led by soluble factors (FGF7/10) induction regulated by cell traction force derived from the tissue deformation. Our findings suggest that cells sense the mechanics of their surrounding environment and alter their properties for self-organization and the following tissue morphogenesis. Also, physically designed hydrogel material is a valuable tool for producing the biomimetic microenvironment to explore how physical cues affect tissue morphogenesis and to modulate tissue morphogenesis for in vitro tissue synthesis.
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Affiliation(s)
- Hiroyuki Miyajima
- Department of Biomaterials Science, Osaka University, 1-8 Yamada-Oka, Suita, Osaka 565-0871, Japan
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Schulte G. International Union of Basic and Clinical Pharmacology. LXXX. The class Frizzled receptors. Pharmacol Rev 2011; 62:632-67. [PMID: 21079039 DOI: 10.1124/pr.110.002931] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The receptor class Frizzled, which has recently been categorized as a separate group of G protein-coupled receptors by the International Union of Basic and Clinical Pharmacology, consists of 10 Frizzleds (FZD(1-10)) and Smoothened (SMO). The FZDs are activated by secreted lipoglycoproteins of the Wingless/Int-1 (WNT) family, whereas SMO is indirectly activated by the Hedgehog (HH) family of proteins acting on the transmembrane protein Patched (PTCH). Recent years have seen major advances in our knowledge about these seven-transmembrane-spanning proteins, including: receptor function, molecular mechanisms of signal transduction, and the receptor's role in embryonic patterning, physiology, cancer, and other diseases. Despite intense efforts, many question marks and challenges remain in mapping receptor-ligand interaction, signaling routes, mechanisms of specificity and how these molecular details underlie disease and also the receptor's important role in physiology. This review therefore focuses on the molecular aspects of WNT/FZD and HH/SMO signaling discussing receptor structure, mechanisms of signal transduction, accessory proteins, receptor dynamics, and the possibility of targeting these signaling pathways pharmacologically.
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Affiliation(s)
- Gunnar Schulte
- Section of Receptor Biology & Signaling, Dept. of Physiology & Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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Kim HY, Davidson LA. Punctuated actin contractions during convergent extension and their permissive regulation by the non-canonical Wnt-signaling pathway. J Cell Sci 2011; 124:635-46. [PMID: 21266466 PMCID: PMC3031374 DOI: 10.1242/jcs.067579] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2010] [Indexed: 12/18/2022] Open
Abstract
Actomyosin networks linked to the micro-environment through the plasma membrane are thought to be key players in regulating cell behaviors within multicellular tissues, such as converging and extending mesoderm. Here, we observe the dynamics of actin contractions called 'punctuated actin contractions' in the mid-cell body of embryonic mesenchymal cells in the mesoderm. These contraction dynamics are a common feature of Xenopus embryonic tissues and are important for cell shape changes during morphogenesis. Quantitative morphological analysis of these F-actin dynamics indicates that frequent and aligned movements of multiple actin contractions accompany mesoderm cells as they intercalate and elongate. Using inhibitors combined with fluorescence recovery after photobleaching (FRAP) analysis, we find that the dynamics of actin contractions are regulated by both myosin contractility and F-actin polymerization. Furthermore, we find that the non-canonical Wnt-signaling pathway permissively regulates levels of punctuated actin contractions. Overexpression of Xfz7 (Fzd7) can induce early maturation of actin contractions in mesoderm and produce mesoderm-like actin contractions in ectoderm cells. By contrast, expression of the dominant-negative Xenopus disheveled construct Xdd1 blocks the progression of actin contractions into their late mesoderm dynamics but has no effect in ectoderm. Our study reveals punctuated actin contractions within converging and extending mesoderm and uncovers a permissive role for non-canonical Wnt-signaling, myosin contractility and F-actin polymerization in regulating these dynamics.
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Affiliation(s)
- Hye Young Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Lance A. Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Abstract
Morphogenesis requires the spatial and temporal control of embryo mechanics, including force production and mechanical resistance to those forces, to coordinate tissue deformation and large-scale movements. Thus, biomechanical processes play a key role in directly shaping the embryo. Additional roles for embryo mechanics during development may include the patterning of positional information and to provide feedback to ensure the success of morphogenetic movements in shaping the larval body and organs. To understand the multiple roles of mechanics during development requires familiarity with engineering principles of the mechanics of structures, the viscoelastic properties of biomaterials, and the integration of force and stress within embryonic structures as morphogenesis progresses. In this chapter, we review the basic engineering principles of biomechanics as they relate to morphogenesis, introduce methods for quantifying embryo mechanics and the limitations of these methods, and outline a formalism for investigating the role of embryo mechanics in birth defects. We encourage the nascent field of embryo mechanics to adopt standard engineering terms and test methods so that studies of diverse organisms can be compared and universal biomechanical principles can be revealed.
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Affiliation(s)
- Lance A Davidson
- Department of Bioengineering and Developmental Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Tamulonis C, Postma M, Marlow HQ, Magie CR, de Jong J, Kaandorp J. A cell-based model of Nematostella vectensis gastrulation including bottle cell formation, invagination and zippering. Dev Biol 2010; 351:217-28. [PMID: 20977902 DOI: 10.1016/j.ydbio.2010.10.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 08/30/2010] [Accepted: 10/09/2010] [Indexed: 11/28/2022]
Abstract
The gastrulation of Nematostella vectensis, the starlet sea anemone, is morphologically simple yet involves many conserved cell behaviors such as apical constriction, invagination, bottle cell formation, cell migration and zippering found during gastrulation in a wide range of more morphologically complex animals. In this article we study Nematostella gastrulation using a combination of morphometrics and computational modeling. Through this analysis we frame gastrulation as a non-trivial problem, in which two distinct cell domains must change shape to match each other geometrically, while maintaining the integrity of the embryo. Using a detailed cell-based model capable of representing arbitrary cell-shapes such as bottle cells, as well as filopodia, localized adhesion and constriction, we are able to simulate gastrulation and associate emergent macroscopic changes in embryo shape to individual cell behaviors. We have developed a number of testable hypotheses based on the model. First, we hypothesize that the blastomeres need to be stiffer at their apical ends, relative to the rest of the cell perimeter, in order to be able to hold their wedge shape and the dimensions of the blastula, regardless of whether the blastula is sealed or leaky. We also postulate that bottle cells are a consequence of cell strain and low cell-cell adhesion, and can be produced within an epithelium even without apical constriction. Finally, we postulate that apical constriction, filopodia and de-epithelialization are necessary and sufficient for gastrulation based on parameter variation studies.
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Affiliation(s)
- Carlos Tamulonis
- Section for Computational Science, Universiteit van Amsterdam, Science Park 107, 1098 XG Amsterdam, The Netherlands
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Varner VD, Voronov DA, Taber LA. Mechanics of head fold formation: investigating tissue-level forces during early development. Development 2010; 137:3801-11. [PMID: 20929950 DOI: 10.1242/dev.054387] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During its earliest stages, the avian embryo is approximately planar. Through a complex series of folds, this flat geometry is transformed into the intricate three-dimensional structure of the developing organism. Formation of the head fold (HF) is the first step in this cascading sequence of out-of-plane tissue folds. The HF establishes the anterior extent of the embryo and initiates heart, foregut and brain development. Here, we use a combination of computational modeling and experiments to determine the physical forces that drive HF formation. Using chick embryos cultured ex ovo, we measured: (1) changes in tissue morphology in living embryos using optical coherence tomography (OCT); (2) morphogenetic strains (deformations) through the tracking of tissue labels; and (3) regional tissue stresses using changes in the geometry of circular wounds punched through the blastoderm. To determine the physical mechanisms that generate the HF, we created a three-dimensional computational model of the early embryo, consisting of pseudoelastic plates representing the blastoderm and vitelline membrane. Based on previous experimental findings, we simulated the following morphogenetic mechanisms: (1) convergent extension in the neural plate (NP); (2) cell wedging along the anterior NP border; and (3) autonomous in-plane deformations outside the NP. Our numerical predictions agree relatively well with the observed morphology, as well as with our measured stress and strain distributions. The model also predicts the abnormal tissue geometries produced when development is mechanically perturbed. Taken together, the results suggest that the proposed morphogenetic mechanisms provide the main tissue-level forces that drive HF formation.
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Affiliation(s)
- Victor D Varner
- Department of Biomedical Engineering, Washington University, St Louis, MO 63130, USA
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Aller MA, Arias JI, Arias J. Pathological axes of wound repair: gastrulation revisited. Theor Biol Med Model 2010; 7:37. [PMID: 20840764 PMCID: PMC2945962 DOI: 10.1186/1742-4682-7-37] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 09/14/2010] [Indexed: 02/06/2023] Open
Abstract
Post-traumatic inflammation is formed by molecular and cellular complex mechanisms whose final goal seems to be injured tissue regeneration. In the skin -an exterior organ of the body- mechanical or thermal injury induces the expression of different inflammatory phenotypes that resemble similar phenotypes expressed during embryo development. Particularly, molecular and cellular mechanisms involved in gastrulation return. This is a developmental phase that delineates the three embryonic germ layers: ectoderm, endoderm and mesoderm. Consequently, in the post-natal wounded skin, primitive functions related with the embryonic mesoderm, i.e. amniotic and yolk sac-derived, are expressed. Neurogenesis and hematogenesis stand out among the primitive function mechanisms involved. Interestingly, in these phases of the inflammatory response, whose molecular and cellular mechanisms are considered as traces of the early phases of the embryonic development, the mast cell, a cell that is supposedly inflammatory, plays a key role. The correlation that can be established between the embryonic and the inflammatory events suggests that the results obtained from the research regarding both great fields of knowledge must be interchangeable to obtain the maximum advantage.
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Affiliation(s)
- Maria-Angeles Aller
- Surgery I Department, School of Medicine, Complutense University of Madrid, Madrid, Spain
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