1
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Horo U, Clarke DN, Martin AC. Drosophila Fog/Cta and T48 pathways have overlapping and distinct contributions to mesoderm invagination. Mol Biol Cell 2024; 35:ar69. [PMID: 38536475 PMCID: PMC11151099 DOI: 10.1091/mbc.e24-02-0050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 04/13/2024] Open
Abstract
The regulation of the cytoskeleton by multiple signaling pathways, sometimes in parallel, is a common principle of morphogenesis. A classic example of regulation by parallel pathways is Drosophila gastrulation, where the inputs from the Folded gastrulation (Fog)/Concertina (Cta) and the T48 pathways induce apical constriction and mesoderm invagination. Whether there are distinct roles for these separate pathways in regulating the complex spatial and temporal patterns of cytoskeletal activity that accompany early embryo development is still poorly understood. We investigated the roles of the Fog/Cta and T48 pathways and found that, by themselves, the Cta and T48 pathways both promote timely mesoderm invagination and apical myosin II accumulation, with Cta being required for timely cell shape change ahead of mitotic cell division. We also identified distinct functions of T48 and Cta in regulating cellularization and the uniformity of the apical myosin II network, respectively. Our results demonstrate that both redundant and distinct functions for the Fog/Cta and T48 pathways exist.
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Affiliation(s)
- Uzuki Horo
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139
| | - D. Nathaniel Clarke
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139
| | - Adam C. Martin
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139
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2
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Paci G, Mao Y. Forced into shape: Mechanical forces in Drosophila development and homeostasis. Semin Cell Dev Biol 2021; 120:160-170. [PMID: 34092509 PMCID: PMC8681862 DOI: 10.1016/j.semcdb.2021.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 12/03/2022]
Abstract
Mechanical forces play a central role in shaping tissues during development and maintaining epithelial integrity in homeostasis. In this review, we discuss the roles of mechanical forces in Drosophila development and homeostasis, starting from the interplay of mechanics with cell growth and division. We then discuss several examples of morphogenetic processes where complex 3D structures are shaped by mechanical forces, followed by a closer look at patterning processes. We also review the role of forces in homeostatic processes, including cell elimination and wound healing. Finally, we look at the interplay of mechanics and developmental robustness and discuss open questions in the field, as well as novel approaches that will help tackle them in the future.
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Affiliation(s)
- Giulia Paci
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; Institute for the Physics of Living Systems, University College London, Gower Street, London WC1E 6BT, UK
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; Institute for the Physics of Living Systems, University College London, Gower Street, London WC1E 6BT, UK.
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3
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Zhu Y, Deng S, Zhao X, Xia G, Zhao R, Chan HF. Deciphering and engineering tissue folding: A mechanical perspective. Acta Biomater 2021; 134:32-42. [PMID: 34325076 DOI: 10.1016/j.actbio.2021.07.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 07/16/2021] [Accepted: 07/21/2021] [Indexed: 12/19/2022]
Abstract
The folding of tissues/organs into complex shapes is a common phenomenon that occurs in organisms such as animals and plants, and is both structurally and functionally important. Deciphering the process of tissue folding and applying this knowledge to engineer folded systems would significantly advance the field of tissue engineering. Although early studies focused on investigating the biochemical signaling events that occur during the folding process, the physical or mechanical aspects of the process have received increasing attention in recent years. In this review, we will summarize recent findings on the mechanical aspects of folding and introduce strategies by which folding can be controlled in vitro. Emphasis will be placed on the folding events triggered by mechanical effects at the cellular and tissue levels and on the different cell- and biomaterial-based approaches used to recapitulate folding. Finally, we will provide a perspective on the development of engineering tissue folding toward preclinical and clinical translation. STATEMENT OF SIGNIFICANCE: Tissue folding is a common phenomenon in a variety of organisms including human, and has been shown to serve important structural and functional roles. Understanding how folding forms and applying the concept in tissue engineering would represent an advance of the research field. Recently, the physical or mechanical aspect of tissue folding has gained increasing attention. In this review, we will cover recent findings of the mechanical aspect of folding mechanisms, and introduce strategies to control the folding process in vitro. We will also provide a perspective on the future development of the field towards preclinical and clinical translation of various bio fabrication technologies.
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Affiliation(s)
- Yanlun Zhu
- Institute for Tissue Engineering and Regenerative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Key Laboratory for Regenerative Medicine of the Ministry of Education of China, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Shuai Deng
- Institute for Tissue Engineering and Regenerative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Key Laboratory for Regenerative Medicine of the Ministry of Education of China, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Xiaoyu Zhao
- Institute for Tissue Engineering and Regenerative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Key Laboratory for Regenerative Medicine of the Ministry of Education of China, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Guanggai Xia
- Department of General Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Rd, Shanghai 200233, China
| | - Ruike Zhao
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH, 43210, USA
| | - Hon Fai Chan
- Institute for Tissue Engineering and Regenerative Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Key Laboratory for Regenerative Medicine of the Ministry of Education of China, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China; Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China; Hong Kong Branch of CAS Center for Excellence in Animal Evolution and Genetics, Hong Kong SAR, China.
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4
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Kögler AC, Kherdjemil Y, Bender K, Rabinowitz A, Marco-Ferreres R, Furlong EEM. Extremely rapid and reversible optogenetic perturbation of nuclear proteins in living embryos. Dev Cell 2021; 56:2348-2363.e8. [PMID: 34363757 PMCID: PMC8387026 DOI: 10.1016/j.devcel.2021.07.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 04/18/2021] [Accepted: 07/15/2021] [Indexed: 11/27/2022]
Abstract
Many developmental regulators have complex and context-specific roles in different tissues and stages, making the dissection of their function extremely challenging. As regulatory processes often occur within minutes, perturbation methods that match these dynamics are needed. Here, we present the improved light-inducible nuclear export system (iLEXY), an optogenetic loss-of-function approach that triggers translocation of proteins from the nucleus to the cytoplasm. By introducing a series of mutations, we substantially increased LEXY's efficiency and generated variants with different recovery times. iLEXY enables rapid (t1/2 < 30 s), efficient, and reversible nuclear protein depletion in embryos, and is generalizable to proteins of diverse sizes and functions. Applying iLEXY to the Drosophila master regulator Twist, we phenocopy loss-of-function mutants, precisely map the Twist-sensitive embryonic stages, and investigate the effects of timed Twist depletions. Our results demonstrate the power of iLEXY to dissect the function of pleiotropic factors during embryogenesis with unprecedented temporal precision.
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Affiliation(s)
- Anna C Kögler
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Yacine Kherdjemil
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Katharina Bender
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Adam Rabinowitz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Raquel Marco-Ferreres
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Eileen E M Furlong
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany.
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5
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Holcomb MC, Gao GJJ, Servati M, Schneider D, McNeely PK, Thomas JH, Blawzdziewicz J. Mechanical feedback and robustness of apical constrictions in Drosophila embryo ventral furrow formation. PLoS Comput Biol 2021; 17:e1009173. [PMID: 34228708 PMCID: PMC8284804 DOI: 10.1371/journal.pcbi.1009173] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 07/16/2021] [Accepted: 06/10/2021] [Indexed: 11/19/2022] Open
Abstract
Formation of the ventral furrow in the Drosophila embryo relies on the apical constriction of cells in the ventral region to produce bending forces that drive tissue invagination. In our recent paper we observed that apical constrictions during the initial phase of ventral furrow formation produce elongated patterns of cellular constriction chains prior to invagination and argued that these are indicative of tensile stress feedback. Here, we quantitatively analyze the constriction patterns preceding ventral furrow formation and find that they are consistent with the predictions of our active-granular-fluid model of a monolayer of mechanically coupled stress-sensitive constricting particles. Our model shows that tensile feedback causes constriction chains to develop along underlying precursor tensile stress chains that gradually strengthen with subsequent cellular constrictions. As seen in both our model and available optogenetic experiments, this mechanism allows constriction chains to penetrate or circumvent zones of reduced cell contractility, thus increasing the robustness of ventral furrow formation to spatial variation of cell contractility by rescuing cellular constrictions in the disrupted regions.
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Affiliation(s)
- Michael C. Holcomb
- Department of Physics and Astronomy, Texas Tech University, Lubbock, Texas, United States of America
| | - Guo-Jie Jason Gao
- Department of Mathematical and Systems Engineering, Shizuoka University, Hamamatsu, Japan
| | - Mahsa Servati
- Department of Physics and Astronomy, Texas Tech University, Lubbock, Texas, United States of America
| | - Dylan Schneider
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas, United States of America
| | - Presley K. McNeely
- Department of Physics and Astronomy, Texas Tech University, Lubbock, Texas, United States of America
| | - Jeffrey H. Thomas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America
| | - Jerzy Blawzdziewicz
- Department of Physics and Astronomy, Texas Tech University, Lubbock, Texas, United States of America
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas, United States of America
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6
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Tozluoǧlu M, Mao Y. On folding morphogenesis, a mechanical problem. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190564. [PMID: 32829686 DOI: 10.1098/rstb.2019.0564] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Tissue folding is a fundamental process that sculpts a simple flat epithelium into a complex three-dimensional organ structure. Whether it is the folding of the brain, or the looping of the gut, it has become clear that to generate an invagination or a fold of any form, mechanical asymmetries must exist in the epithelium. These mechanical asymmetries can be generated locally, involving just the invaginating cells and their immediate neighbours, or on a more global tissue-wide scale. Here, we review the different mechanical mechanisms that epithelia have adopted to generate folds, and how the use of precisely defined mathematical models has helped decipher which mechanisms are the key driving forces in different epithelia. This article is part of a discussion meeting issue 'Contemporary morphogenesis'.
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Affiliation(s)
- Melda Tozluoǧlu
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.,Institute for the Physics of Living Systems, University College London, Gower Street, London WC1E 6BT, UK
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7
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Gheisari E, Aakhte M, Müller HAJ. Gastrulation in Drosophila melanogaster: Genetic control, cellular basis and biomechanics. Mech Dev 2020; 163:103629. [PMID: 32615151 DOI: 10.1016/j.mod.2020.103629] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 06/08/2020] [Accepted: 06/24/2020] [Indexed: 01/31/2023]
Abstract
Gastrulation is generally understood as the morphogenetic processes that result in the spatial organization of the blastomere into the three germ layers, ectoderm, mesoderm and endoderm. This review summarizes our current knowledge of the morphogenetic mechanisms in Drosophila gastrulation. In addition to the events that drive mesoderm invagination and germband elongation, we pay particular attention to other, less well-known mechanisms including midgut invagination, cephalic furrow formation, dorsal fold formation, and mesoderm layer formation. This review covers topics ranging from the identification and functional characterization of developmental and morphogenetic control genes to the analysis of the physical properties of cells and tissues and the control of cell and tissue mechanics of the morphogenetic movements in the gastrula.
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Affiliation(s)
- Elham Gheisari
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany
| | - Mostafa Aakhte
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany
| | - H-Arno J Müller
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany.
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8
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Martin AC. The Physical Mechanisms of Drosophila Gastrulation: Mesoderm and Endoderm Invagination. Genetics 2020; 214:543-560. [PMID: 32132154 PMCID: PMC7054018 DOI: 10.1534/genetics.119.301292] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/21/2019] [Indexed: 12/14/2022] Open
Abstract
A critical juncture in early development is the partitioning of cells that will adopt different fates into three germ layers: the ectoderm, the mesoderm, and the endoderm. This step is achieved through the internalization of specified cells from the outermost surface layer, through a process called gastrulation. In Drosophila, gastrulation is achieved through cell shape changes (i.e., apical constriction) that change tissue curvature and lead to the folding of a surface epithelium. Folding of embryonic tissue results in mesoderm and endoderm invagination, not as individual cells, but as collective tissue units. The tractability of Drosophila as a model system is best exemplified by how much we know about Drosophila gastrulation, from the signals that pattern the embryo to the molecular components that generate force, and how these components are organized to promote cell and tissue shape changes. For mesoderm invagination, graded signaling by the morphogen, Spätzle, sets up a gradient in transcriptional activity that leads to the expression of a secreted ligand (Folded gastrulation) and a transmembrane protein (T48). Together with the GPCR Mist, which is expressed in the mesoderm, and the GPCR Smog, which is expressed uniformly, these signals activate heterotrimeric G-protein and small Rho-family G-protein signaling to promote apical contractility and changes in cell and tissue shape. A notable feature of this signaling pathway is its intricate organization in both space and time. At the cellular level, signaling components and the cytoskeleton exhibit striking polarity, not only along the apical-basal cell axis, but also within the apical domain. Furthermore, gene expression controls a highly choreographed chain of events, the dynamics of which are critical for primordium invagination; it does not simply throw the cytoskeletal "on" switch. Finally, studies of Drosophila gastrulation have provided insight into how global tissue mechanics and movements are intertwined as multiple tissues simultaneously change shape. Overall, these studies have contributed to the view that cells respond to forces that propagate over great distances, demonstrating that cellular decisions, and, ultimately, tissue shape changes, proceed by integrating cues across an entire embryo.
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Affiliation(s)
- Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
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9
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The cellular and molecular mechanisms that establish the mechanics of Drosophila gastrulation. Curr Top Dev Biol 2020; 136:141-165. [DOI: 10.1016/bs.ctdb.2019.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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10
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Francou A, Anderson KV. The Epithelial-to-Mesenchymal Transition (EMT) in Development and Cancer. ANNUAL REVIEW OF CANCER BIOLOGY-SERIES 2019; 4:197-220. [PMID: 34113749 DOI: 10.1146/annurev-cancerbio-030518-055425] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Epithelial-to-mesenchymal transitions (EMTs) are complex cellular processes where cells undergo dramatic changes in signaling, transcriptional programming, and cell shape, while directing the exit of cells from the epithelium and promoting migratory properties of the resulting mesenchyme. EMTs are essential for morphogenesis during development and are also a critical step in cancer progression and metastasis formation. Here we provide an overview of the molecular regulation of the EMT process during embryo development, focusing on chick and mouse gastrulation and neural crest development. We go on to describe how EMT regulators participate in the progression of pancreatic and breast cancer in mouse models, and discuss the parallels with developmental EMTs and how these help to understand cancer EMTs. We also highlight the differences between EMTs in tumor and in development to arrive at a broader view of cancer EMT. We conclude by discussing how further advances in the field will rely on in vivo dynamic imaging of the cellular events of EMT.
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Affiliation(s)
- Alexandre Francou
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York NY 10065 USA
| | - Kathryn V Anderson
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York NY 10065 USA
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11
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Benton MA, Frey N, Nunes da Fonseca R, von Levetzow C, Stappert D, Hakeemi MS, Conrads KH, Pechmann M, Panfilio KA, Lynch JA, Roth S. Fog signaling has diverse roles in epithelial morphogenesis in insects. eLife 2019; 8:47346. [PMID: 31573513 PMCID: PMC6794076 DOI: 10.7554/elife.47346] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/30/2019] [Indexed: 12/14/2022] Open
Abstract
The Drosophila Fog pathway represents one of the best-understood signaling cascades controlling epithelial morphogenesis. During gastrulation, Fog induces apical cell constrictions that drive the invagination of mesoderm and posterior gut primordia. The cellular mechanisms underlying primordia internalization vary greatly among insects and recent work has suggested that Fog signaling is specific to the fast mode of gastrulation found in some flies. On the contrary, here we show in the beetle Tribolium, whose development is broadly representative for insects, that Fog has multiple morphogenetic functions. It modulates mesoderm internalization and controls a massive posterior infolding involved in gut and extraembryonic development. In addition, Fog signaling affects blastoderm cellularization, primordial germ cell positioning, and cuboidal-to-squamous cell shape transitions in the extraembryonic serosa. Comparative analyses with two other distantly related insect species reveals that Fog's role during cellularization is widely conserved and therefore might represent the ancestral function of the pathway.
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Affiliation(s)
- Matthew Alan Benton
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany.,Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Nadine Frey
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | | | - Cornelia von Levetzow
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Dominik Stappert
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Muhammad Salim Hakeemi
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Kai H Conrads
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Matthias Pechmann
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
| | - Kristen A Panfilio
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Jeremy A Lynch
- Department of Biological Sciences, University of Illinois, Chicago, United States
| | - Siegfried Roth
- Institute for Zoology/Developmental Biology, Biocenter, University of Cologne, Köln, Germany
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12
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Bailles A, Collinet C, Philippe JM, Lenne PF, Munro E, Lecuit T. Genetic induction and mechanochemical propagation of a morphogenetic wave. Nature 2019; 572:467-473. [PMID: 31413363 DOI: 10.1038/s41586-019-1492-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 07/10/2019] [Indexed: 02/06/2023]
Abstract
Tissue morphogenesis arises from coordinated changes in cell shape driven by actomyosin contractions. Patterns of gene expression regionalize cell behaviours by controlling actomyosin contractility. Here we report two modes of control over Rho1 and myosin II (MyoII) activation in the Drosophila endoderm. First, Rho1-MyoII are induced in a spatially restricted primordium via localized transcription of the G-protein-coupled receptor ligand Fog. Second, a tissue-scale wave of Rho1-MyoII activation and cell invagination progresses anteriorly away from the primordium. The wave does not require sustained gene transcription, and is not governed by regulated Fog delivery. Instead, MyoII inhibition blocks Rho1 activation and propagation, revealing a mechanical feedback driven by MyoII. We find that MyoII activation and invagination in each row of cells drives adhesion to the vitelline membrane mediated by integrins, apical spreading, MyoII activation and invagination in the next row. Endoderm morphogenesis thus emerges from local transcriptional initiation and a mechanically driven cycle of cell deformation.
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Affiliation(s)
- Anaïs Bailles
- IBDM-UMR7288, Aix Marseille Université and CNRS, Marseille, France.,Turing Centre for Living Systems, Marseille, France
| | - Claudio Collinet
- IBDM-UMR7288, Aix Marseille Université and CNRS, Marseille, France. .,Turing Centre for Living Systems, Marseille, France.
| | - Jean-Marc Philippe
- IBDM-UMR7288, Aix Marseille Université and CNRS, Marseille, France.,Turing Centre for Living Systems, Marseille, France
| | - Pierre-François Lenne
- IBDM-UMR7288, Aix Marseille Université and CNRS, Marseille, France.,Turing Centre for Living Systems, Marseille, France
| | - Edwin Munro
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Thomas Lecuit
- IBDM-UMR7288, Aix Marseille Université and CNRS, Marseille, France. .,Turing Centre for Living Systems, Marseille, France. .,Collège de France, Paris, France.
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13
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Ermakov AS. Professor Lev Beloussov and the birth of morphomechanics. Biosystems 2018; 173:26-35. [PMID: 30315822 DOI: 10.1016/j.biosystems.2018.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 10/06/2018] [Accepted: 10/08/2018] [Indexed: 12/14/2022]
Abstract
The first explanations of the mechanisms of development of living organisms were proposed in antiquity. At that time two competing ideas existed, about the strict determination of embryonic structures (we call it the "Hippocrates line") and about the possible formation of structures from the unstructured condition ("Aristotle line"). We can trace the opposition between the "Hippocrates line" and "Aristotle line" from antiquity till the present time. At the end of the XIX century, experimental investigation of the mechanisms of integrity of development had started. In the XX century, the "Aristotle line" finds its expression in the Morphogenetic Field Theory of A.G. Gurwitsch, according to which cells of the organism are integrated in an organic whole. Since the 1970s, mechanical forces and tensions have been considered as integral factors of ontogenesis. One of the most productive scientific teams which worked in this area was the laboratory of Professor L.V. Beloussov from the Lomonossov Moscow State University, Russia. In the 1970s, Lev Beloussov and his colleagues discovered the presence of "passive" and "active" (i.e. metabolically-dependent) mechanical stresses in the tissues of developing organisms, their organization and stage-specific patterns. In 1980-1990 s, a lot of experimental data about the role of the patterns of mechanical stresses in morphogenesis and cell differentiation was accumulated. Based on the experimental data, Professor Beloussov and his colleagues developed a theory of the regulation of the development of living organisms on the basis of the interaction of passive and active mechanical stresses (Belousov-Mittenthal Theory), which forms the basis of a new science - morphomechanics.
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Affiliation(s)
- Alexander S Ermakov
- Lomonossov Moscow State University, Faculty of Biology, Department of Embryology, 119991, Moscow, Leninskie Gory, 1-12, Russia; Federal State Budgetary Research Institution "Institute of Experimental Medicine", Department of Experimental Physiology, 197376, St Petersburg, Akad. Pavlova Str 12, Russia.
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14
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Bredov D, Volodyaev I. Increasing complexity: Mechanical guidance and feedback loops as a basis for self-organization in morphogenesis. Biosystems 2018; 173:133-156. [PMID: 30292533 DOI: 10.1016/j.biosystems.2018.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/26/2018] [Accepted: 10/01/2018] [Indexed: 10/28/2022]
Abstract
The article is devoted to physical views on embryo development as a combination of structurally stable dynamics and symmetry-breaking events in the general process of self-organization. The first corresponds to the deterministic aspect of embryo development. The second type of processes is associated with sudden increase of variability in the periods of symmetry-breaking, which manifests unstable dynamics. The biological basis under these considerations includes chemokinetics (a system of inductors, repressors, and interaction with their next surrounding) and morphomechanics (i.e. mechanotransduction, mechanosensing, and related feedback loops). Although the latter research area is evolving rapidly, up to this time the role of mechanical properties of embryonic tissues and mechano-dependent processes in them are integrated in the general picture of embryo development to a lesser extent than biochemical signaling. For this reason, the present article is mostly devoted to experimental data on morphomechanics in the process of embryo development, also including analysis of its limitations and possible contradictions. The general system of feedback-loops and system dynamics delineated in this review is in large part a repetition of the views of Lev Beloussov, who was one of the founders of the whole areas of morphomechanics and morphodynamics, and to whose memory this article is dedicated.
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Affiliation(s)
- Denis Bredov
- Laboratory of Developmental biophysics, Department of Embryology, Faculty of Biology, Moscow State University, Moscow, 119234, Russia
| | - Ilya Volodyaev
- Laboratory of Developmental biophysics, Department of Embryology, Faculty of Biology, Moscow State University, Moscow, 119234, Russia.
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15
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Pasiliao CC, Hopyan S. Cell ingression: Relevance to limb development and for adaptive evolution. Genesis 2017; 56. [PMID: 29280270 DOI: 10.1002/dvg.23086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 11/16/2017] [Accepted: 12/05/2017] [Indexed: 12/11/2022]
Abstract
Cell ingression is an out-of-plane type of cell intercalation that is essential for the formation of multiple embryonic structures including the limbs. In particular, cell ingression underlies epithelial-to-mesenchymal transition of lateral plate cells to initiate limb bud growth, delamination of neural crest cells to generate peripheral nerve sheaths, and emigration of myoblasts from somites to assemble muscles. Individual cells that ingress undergo apical constriction to generate bottle shaped cells, diminish adhesion to their epithelial cell neighbors, and generate protrusive blebs that likely facilitate their ingression into a subepithelial tissue layer. How signaling pathways regulate the progression of delamination is important for understanding numerous developmental events. In this review, we focus on cellular and molecular mechanisms that drive cell ingression and draw comparisons between different morphogenetic contexts in various model organisms. We speculate that cell behaviors that facilitated tissue invagination among diploblasts subsequently drove individual cell ingression and epithelial-to-mesenchymal transition. Future insights that link signalling pathways to biophysical mechanisms will likely advance our comprehension of this phenomenon.
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Affiliation(s)
- Clarissa C Pasiliao
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada
| | - Sevan Hopyan
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada.,Division of Orthopaedic Surgery, Hospital for Sick Children and University of, Toronto, M5G 1X8, Canada
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16
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Chung S, Kim S, Andrew DJ. Uncoupling apical constriction from tissue invagination. eLife 2017; 6. [PMID: 28263180 PMCID: PMC5338918 DOI: 10.7554/elife.22235] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 02/07/2017] [Indexed: 12/03/2022] Open
Abstract
Apical constriction is a widely utilized cell shape change linked to folding, bending and invagination of polarized epithelia. It remains unclear how apical constriction is regulated spatiotemporally during tissue invagination and how this cellular process contributes to tube formation in different developmental contexts. Using Drosophila salivary gland (SG) invagination as a model, we show that regulation of folded gastrulation expression by the Fork head transcription factor is required for apicomedial accumulation of Rho kinase and non-muscle myosin II, which coordinate apical constriction. We demonstrate that neither loss of spatially coordinated apical constriction nor its complete blockage prevent internalization and tube formation, although such manipulations affect the geometry of invagination. When apical constriction is disrupted, compressing force generated by a tissue-level myosin cable contributes to SG invagination. We demonstrate that fully elongated polarized SGs can form outside the embryo, suggesting that tube formation and elongation are intrinsic properties of the SG. DOI:http://dx.doi.org/10.7554/eLife.22235.001 Many organs in the human body – like the kidneys, lungs, and salivary glands – are organized as a single layer of cells that surround a hollow tube. There are a number of ways that cells can achieve this particular arrangement. In one mechanism, a small group of cells bud out of a single cell layer to become the end of a new tube or a new branch of an existing tube. Since all the cells are still connected, the first cells bring their neighbouring cells along behind them, rearranging these cells to form the walls of a tube. In addition to changing position, the cells must change their shape to form a tube. One crucial change in cell shape is called apical constriction, and involves the side of the cell facing the inside of the tube becoming smaller than the other sides. This creates cells with a wedge-like shape that can fit together to form the curved wall of the tube, similar to shaped bricks in an archway. Apical constriction has been widely studied and is controlled by proteins that act like motors moving along protein-based filaments; however the roles of apical constriction in tube formation have not been fully explained. Using the developing salivary glands of the fruit fly Drosophila melanogaster, Chung et al. confirmed that the motor protein known as myosin II controls apical constriction during tissue invagination. Further examination showed that proteins (called Fork Head and Fog) activate and localize an enzyme (Rho kinase) to control the localized accumulation of myosin II and thereby control apical constriction. Chung et al. then showed that salivary glands could still form tubes if apical constriction was blocked, indicating that it is not an essential part of tissue invagination in this organ. However, blocking apical constriction led the tube to develop unusual shapes at intermediate stages. More work is now needed to better understand the links between apical constriction, cell rearrangement and tissue invagination. These processes are fundamental for organs to form correctly in many organisms and understanding their control could have wide-ranging impacts. A better understanding of these processes may provide insight into how the tubes can form while keeping all the cells adequately supplied with oxygen and nutrients, and into diseases that result if there are defects in the invagination process. DOI:http://dx.doi.org/10.7554/eLife.22235.002
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Affiliation(s)
- SeYeon Chung
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Sangjoon Kim
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Deborah J Andrew
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, United States
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17
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Mechanotransductive cascade of Myo-II-dependent mesoderm and endoderm invaginations in embryo gastrulation. Nat Commun 2017; 8:13883. [PMID: 28112149 PMCID: PMC5264015 DOI: 10.1038/ncomms13883] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/08/2016] [Indexed: 12/31/2022] Open
Abstract
Animal development consists of a cascade of tissue differentiation and shape change. Associated mechanical signals regulate tissue differentiation. Here we demonstrate that endogenous mechanical cues also trigger biochemical pathways, generating the active morphogenetic movements shaping animal development through a mechanotransductive cascade of Myo-II medio-apical stabilization. To mimic physiological tissue deformation with a cell scale resolution, liposomes containing magnetic nanoparticles are injected into embryonic epithelia and submitted to time-variable forces generated by a linear array of micrometric soft magnets. Periodic magnetically induced deformations quantitatively phenocopy the soft mechanical endogenous snail-dependent apex pulsations, rescue the medio-apical accumulation of Rok, Myo-II and subsequent mesoderm invagination lacking in sna mutants, in a Fog-dependent mechanotransductive process. Mesoderm invagination then activates Myo-II apical accumulation, in a similar Fog-dependent mechanotransductive process, which in turn initiates endoderm invagination. This reveals the existence of a highly dynamic self-inductive cascade of mesoderm and endoderm invaginations, regulated by mechano-induced medio-apical stabilization of Myo-II. Mechanical signals regulate tissue differentiation but how this triggers downstream biochemical signals is unclear. Here, the authors place micro-magnets in the Drosophila embryonic epithelia and show this triggers apical pulsations, in turn stabilizing Myosin-II, resulting in mesoderm invagination.
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18
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Jason Gao GJ, Holcomb MC, Thomas JH, Blawzdziewicz J. Embryo as an active granular fluid: stress-coordinated cellular constriction chains. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:414021. [PMID: 27545101 DOI: 10.1088/0953-8984/28/41/414021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. However, systematic methods of studying how mechanical stress and feedback help to harmonize cellular activities within a tissue have yet to be developed. Motivated by our observation of the cellular constriction chains (CCCs) during the initial phase of ventral furrow formation in the Drosophila melanogaster embryo, we propose an active granular fluid (AGF) model that provides valuable insights into cellular coordination in the apical constriction process. In our model, cells are treated as circular particles connected by a predefined force network, and they undergo a random constriction process in which the particle constriction probability P is a function of the stress exerted on the particle by its neighbors. We find that when P favors tensile stress, constricted particles tend to form chain-like structures. In contrast, constricted particles tend to form compact clusters when P favors compression. A remarkable similarity of constricted-particle chains and CCCs observed in vivo provides indirect evidence that tensile-stress feedback coordinates the apical constriction activity. Our particle-based AGF model will be useful in analyzing mechanical feedback effects in a wide variety of morphogenesis and organogenesis phenomena.
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Affiliation(s)
- Guo-Jie Jason Gao
- Department of Mechanical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
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19
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Urbansky S, González Avalos P, Wosch M, Lemke S. Folded gastrulation and T48 drive the evolution of coordinated mesoderm internalization in flies. eLife 2016; 5. [PMID: 27685537 PMCID: PMC5042651 DOI: 10.7554/elife.18318] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 08/30/2016] [Indexed: 12/17/2022] Open
Abstract
Gastrulation constitutes a fundamental yet diverse morphogenetic process of metazoan development. Modes of gastrulation range from stochastic translocation of individual cells to coordinated infolding of an epithelial sheet. How such morphogenetic differences are genetically encoded and whether they have provided specific developmental advantages is unclear. Here we identify two genes, folded gastrulation and t48, which in the evolution of fly gastrulation acted as a likely switch from an ingression of individual cells to the invagination of the blastoderm epithelium. Both genes are expressed and required for mesoderm invagination in the fruit fly Drosophila melanogaster but do not appear during mesoderm ingression of the midge Chironomus riparius. We demonstrate that early expression of either or both of these genes in C.riparius is sufficient to invoke mesoderm invagination similar to D.melanogaster. The possible genetic simplicity and a measurable increase in developmental robustness might explain repeated evolution of similar transitions in animal gastrulation. DOI:http://dx.doi.org/10.7554/eLife.18318.001 In animals, gastrulation is a period of time in early development during which a sphere of cells is reorganized into an embryo with cells arranged into three distinct layers (called germ layers). The process has changed substantially during the course of evolution and thus provides a great experimental system to investigate the genetic basis for differences in animal form and shape. As an example, true flies use at least two different mechanisms to make the middle germ layer (the mesoderm). In both cases, the mesoderm is made up of cells that move inwards from the boundary of the outer germ layer. In midges and some other flies, these cells migrate individually, while in others including fruit flies, the cells move together as a sheet. Fruit flies and midges shared their last common ancestor 250 million years ago and although the genes that make the mesoderm in fruit flies are well understood, little is known about how the mesoderm forms in midges. Urbansky, González Avalos et al. investigated which genes were responsible for the evolutionary transition between the different types of cell migration seen in flies. The experiments identified two genes – called folded gastrulation and t48 – that seem to operate as a simple switch between the two ways that mesoderm cells migrate. Both of these genes are active in fruit fly embryos and are required for the group migration of mesoderm cells. However, the genes do not appear to play a major role in the movement of individual mesoderm cells in midges. Further experiments demonstrate that switching on these genes in midge embryos is sufficient to invoke group mesoderm cell migrations similar to those seen in fruit flies. These findings show that it is possible to identify genetic changes that underlie substantial differences in animal form and shape over hundred million of years. The ease by which Urbansky, González Avalos et al. were able to switch between the two types of mesoderm migration might explain why similar transitions in gastrulation have evolved repeatedly in animals. The next step is to test this hypothesis in other animals. DOI:http://dx.doi.org/10.7554/eLife.18318.002
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Affiliation(s)
- Silvia Urbansky
- Centre for Organismal Studies Heidelberg, Heidelberg University, Heidelberg, Germany
| | - Paula González Avalos
- Centre for Organismal Studies Heidelberg, Heidelberg University, Heidelberg, Germany
| | - Maike Wosch
- Centre for Organismal Studies Heidelberg, Heidelberg University, Heidelberg, Germany
| | - Steffen Lemke
- Centre for Organismal Studies Heidelberg, Heidelberg University, Heidelberg, Germany
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20
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Sandler JE, Stathopoulos A. Stepwise Progression of Embryonic Patterning. Trends Genet 2016; 32:432-443. [PMID: 27230753 DOI: 10.1016/j.tig.2016.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 01/23/2023]
Abstract
It is long established that the graded distribution of Dorsal transcription factor influences spatial domains of gene expression along the dorsoventral (DV) axis of Drosophila melanogaster embryos. However, the more recent realization that Dorsal levels also change with time raises the question of whether these dynamics are instructive. An overview of DV axis patterning is provided, focusing on new insights identified through quantitative analysis of temporal changes in Dorsal target gene expression from one nuclear cycle to the next ('steps'). Possible roles for the stepwise progression of this patterning program are discussed including (i) tight temporal regulation of signaling pathway activation, (ii) control of gene expression cohorts, and (iii) ensuring the irreversibility of the patterning and cell fate specification process.
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Affiliation(s)
- Jeremy E Sandler
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Angelike Stathopoulos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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21
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Fernandez-Sanchez ME, Brunet T, Röper JC, Farge E. Mechanotransduction's Impact on Animal Development, Evolution, and Tumorigenesis. Annu Rev Cell Dev Biol 2015; 31:373-97. [DOI: 10.1146/annurev-cellbio-102314-112441] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Maria-Elena Fernandez-Sanchez
- Mechanics and Genetics of Embryonic and Tumor Development Team, CNRS UMR 168 Physicochimie Curie, Institut Curie Centre de Recherche, PSL Research University; Fondation Pierre-Gilles de Gennes; and INSERM, F-75005 Paris, France;
| | - Thibaut Brunet
- Mechanics and Genetics of Embryonic and Tumor Development Team, CNRS UMR 168 Physicochimie Curie, Institut Curie Centre de Recherche, PSL Research University; Fondation Pierre-Gilles de Gennes; and INSERM, F-75005 Paris, France;
- Evolution of the Nervous System in Bilateria Group, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
| | - Jens-Christian Röper
- Mechanics and Genetics of Embryonic and Tumor Development Team, CNRS UMR 168 Physicochimie Curie, Institut Curie Centre de Recherche, PSL Research University; Fondation Pierre-Gilles de Gennes; and INSERM, F-75005 Paris, France;
| | - Emmanuel Farge
- Mechanics and Genetics of Embryonic and Tumor Development Team, CNRS UMR 168 Physicochimie Curie, Institut Curie Centre de Recherche, PSL Research University; Fondation Pierre-Gilles de Gennes; and INSERM, F-75005 Paris, France;
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22
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Pocha SM, Montell DJ. Cellular and molecular mechanisms of single and collective cell migrations in Drosophila: themes and variations. Annu Rev Genet 2015; 48:295-318. [PMID: 25421599 DOI: 10.1146/annurev-genet-120213-092218] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The process of cell migration is essential throughout life, driving embryonic morphogenesis and ensuring homeostasis in adults. Defects in cell migration are a major cause of human disease, with excessive migration causing autoimmune diseases and cancer metastasis, whereas reduced capacity for migration leads to birth defects and immunodeficiencies. Myriad studies in vitro have established a consensus view that cell migrations require cell polarization, Rho GTPase-mediated cytoskeletal rearrangements, and myosin-mediated contractility. However, in vivo studies later revealed a more complex picture, including the discovery that cells migrate not only as single units but also as clusters, strands, and sheets. In particular, the role of E-Cadherin in cell motility appears to be more complex than previously appreciated. Here, we discuss recent advances achieved by combining the plethora of genetic tools available to the Drosophila geneticist with live imaging and biophysical techniques. Finally, we discuss the emerging themes such studies have revealed and ponder the puzzles that remain to be solved.
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Affiliation(s)
- Shirin M Pocha
- Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California; 93106-9625; ,
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23
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Dobi KC, Schulman VK, Baylies MK. Specification of the somatic musculature in Drosophila. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2015; 4:357-75. [PMID: 25728002 PMCID: PMC4456285 DOI: 10.1002/wdev.182] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/16/2015] [Accepted: 02/04/2015] [Indexed: 11/09/2022]
Abstract
The somatic muscle system formed during Drosophila embryogenesis is required for larvae to hatch, feed, and crawl. This system is replaced in the pupa by a new adult muscle set, responsible for activities such as feeding, walking, and flight. Both the larval and adult muscle systems are comprised of distinct muscle fibers to serve these specific motor functions. In this way, the Drosophila musculature is a valuable model for patterning within a single tissue: while all muscle cells share properties such as the contractile apparatus, properties such as size, position, and number of nuclei are unique for a particular muscle. In the embryo, diversification of muscle fibers relies first on signaling cascades that pattern the mesoderm. Subsequently, the combinatorial expression of specific transcription factors leads muscle fibers to adopt particular sizes, shapes, and orientations. Adult muscle precursors (AMPs), set aside during embryonic development, proliferate during the larval phases and seed the formation of the abdominal, leg, and flight muscles in the adult fly. Adult muscle fibers may either be formed de novo from the fusion of the AMPs, or are created by the binding of AMPs to an existing larval muscle. While less is known about adult muscle specification compared to the larva, expression of specific transcription factors is also important for its diversification. Increasingly, the mechanisms required for the diversification of fly muscle have found parallels in vertebrate systems and mark Drosophila as a robust model system to examine questions about how diverse cell types are generated within an organism.
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Affiliation(s)
- Krista C. Dobi
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
| | - Victoria K. Schulman
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA
| | - Mary K. Baylies
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA
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24
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Manning AJ, Rogers SL. The Fog signaling pathway: insights into signaling in morphogenesis. Dev Biol 2014; 394:6-14. [PMID: 25127992 PMCID: PMC4182926 DOI: 10.1016/j.ydbio.2014.08.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/28/2014] [Accepted: 08/04/2014] [Indexed: 12/28/2022]
Abstract
Epithelia form the building blocks of many tissue and organ types. Epithelial cells often form a contiguous 2-dimensional sheet that is held together by strong adhesions. The mechanical properties conferred by these adhesions allow the cells to undergo dramatic three-dimensional morphogenetic movements while maintaining cell–cell contacts during embryogenesis and post-embryonic development. The Drosophila Folded gastrulation pathway triggers epithelial cell shape changes that drive gastrulation and tissue folding and is one of the most extensively studied examples of epithelial morphogenesis. This pathway has yielded key insights into the signaling mechanisms and cellular machinery involved in epithelial remodeling. In this review, we discuss principles of morphogenesis and signaling that have been discovered through genetic and cell biological examination of this pathway. We also consider various regulatory mechanisms and the system's relevance to mammalian development. We propose future directions that will continue to broaden our knowledge of morphogenesis across taxa.
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Affiliation(s)
- Alyssa J Manning
- Department of Biochemistry, Box 357350, The University of Washington, Seattle, WA 98195-7350, USA
| | - Stephen L Rogers
- Department of Biology, The University of North Carolina at Chapel Hill, CB ♯3280, Fordham Hall, South Road, Chapel Hill, NC 27599-3280, USA; Lineberger Comprehensive Cancer Center, USA; Carolina Center for Genome Sciences, USA.
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25
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Wong MC, Dobi KC, Baylies MK. Discrete levels of Twist activity are required to direct distinct cell functions during gastrulation and somatic myogenesis. PLoS One 2014; 9:e99553. [PMID: 24915423 PMCID: PMC4051702 DOI: 10.1371/journal.pone.0099553] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 05/16/2014] [Indexed: 01/27/2023] Open
Abstract
Twist (Twi), a conserved basic helix-loop-helix transcriptional regulator, directs the epithelial-to-mesenchymal transition (EMT), and regulates changes in cell fate, cell polarity, cell division and cell migration in organisms from flies to humans. Analogous to its role in EMT, Twist has been implicated in metastasis in numerous cancer types, including breast, pancreatic and prostate. In the Drosophila embryo, Twist is essential for discrete events in gastrulation and mesodermal patterning. In this study, we derive a twi allelic series by examining the various cellular events required for gastrulation in Drosophila. By genetically manipulating the levels of Twi activity during gastrulation, we find that coordination of cell division is the most sensitive cellular event, whereas changes in cell shape are the least sensitive. Strikingly, we show that by increasing levels of Snail expression in a severe twi hypomorphic allelic background, but not a twi null background, we can reconstitute gastrulation and produce viable adult flies. Our results demonstrate that the level of Twi activity determines whether the cellular events of ventral furrow formation, EMT, cell division and mesodermal migration occur.
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Affiliation(s)
- Ming-Ching Wong
- Program in Developmental Biology, Sloan-Kettering Institute, New York, New York, United States of America
- Weill Graduate School at Cornell Medical School, New York, New York, United States of America
| | - Krista C. Dobi
- Program in Developmental Biology, Sloan-Kettering Institute, New York, New York, United States of America
| | - Mary K. Baylies
- Program in Developmental Biology, Sloan-Kettering Institute, New York, New York, United States of America
- Weill Graduate School at Cornell Medical School, New York, New York, United States of America
- * E-mail:
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26
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Abstract
Differential adhesion provides a mechanical force to drive cells into stable configurations during the assembly of tissues and organs. This is well illustrated in the Drosophila eye where differential adhesion plays a role in sequential recruitment of all support cells. Cell adhesion, on the other hand, is linked to the cytoskeleton and subject to regulation by cell signaling. The integration of cell adhesion with the cytoskeleton and cell signaling may provide a more thorough explanation for the diversity of forms and shapes seen in tissues and organs.
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Affiliation(s)
- Sujin Bao
- Saint James School of Medicine , Bonaire , Caribbean Netherlands
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27
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Schäfer G, Narasimha M, Vogelsang E, Leptin M. Cadherin switching during the formation and differentiation of the Drosophila mesoderm - implications for epithelial-to-mesenchymal transitions. J Cell Sci 2014; 127:1511-22. [PMID: 24496448 DOI: 10.1242/jcs.139485] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Epithelial-to-mesenchymal transition (EMT) is typically accompanied by downregulation of epithelial (E-) cadherin, and is often additionally accompanied by upregulation of a mesenchymal or neuronal (N-) cadherin. Snail represses transcription of the E-cadherin gene both during normal development and during tumour spreading. The formation of the mesodermal germ layer in Drosophila, considered a paradigm of a developmental EMT, is associated with Snail-mediated repression of E-cadherin and the upregulation of N-cadherin. By using genetic manipulation to remove or overexpress the cadherins, we show here that the complementarity of cadherin expression is not necessary for the segregation or the dispersal of the mesodermal germ layer in Drosophila. However, we discover different effects of E- and N-cadherin on the differentiation of subsets of mesodermal derivatives, which depend on Wingless signalling from the ectoderm, indicating differing abilities of E- and N-cadherin to bind to and sequester the common junctional and signalling effector β-catenin. These results suggest that the downregulation of E-cadherin in the mesoderm might be required to facilitate optimal levels of Wingless signalling.
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Affiliation(s)
- Gritt Schäfer
- Institute of Genetics, University of Cologne, Zülpicher Strasse 47a, 50674 Cologne, Germany
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28
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Rembold M, Ciglar L, Yáñez-Cuna JO, Zinzen RP, Girardot C, Jain A, Welte MA, Stark A, Leptin M, Furlong EEM. A conserved role for Snail as a potentiator of active transcription. Genes Dev 2014; 28:167-81. [PMID: 24402316 PMCID: PMC3909790 DOI: 10.1101/gad.230953.113] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The transcription factors of the Snail family are key regulators of epithelial-mesenchymal transitions, cell morphogenesis, and tumor metastasis. Since its discovery in Drosophila ∼25 years ago, Snail has been extensively studied for its role as a transcriptional repressor. Here we demonstrate that Drosophila Snail can positively modulate transcriptional activation. By combining information on in vivo occupancy with expression profiling of hand-selected, staged snail mutant embryos, we identified 106 genes that are potentially directly regulated by Snail during mesoderm development. In addition to the expected Snail-repressed genes, almost 50% of Snail targets showed an unanticipated activation. The majority of "Snail-activated" genes have enhancer elements cobound by Twist and are expressed in the mesoderm at the stages of Snail occupancy. Snail can potentiate Twist-mediated enhancer activation in vitro and is essential for enhancer activity in vivo. Using a machine learning approach, we show that differentially enriched motifs are sufficient to predict Snail's regulatory response. In silico mutagenesis revealed a likely causative motif, which we demonstrate is essential for enhancer activation. Taken together, these data indicate that Snail can potentiate enhancer activation by collaborating with different activators, providing a new mechanism by which Snail regulates development.
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Affiliation(s)
- Martina Rembold
- Institute of Genetics, University of Cologne, 50674 Cologne, Germany
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29
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Manning AJ, Peters KA, Peifer M, Rogers SL. Regulation of epithelial morphogenesis by the G protein-coupled receptor mist and its ligand fog. Sci Signal 2013; 6:ra98. [PMID: 24222713 DOI: 10.1126/scisignal.2004427] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Epithelial morphogenesis is essential for shaping organs and tissues and for establishment of the three embryonic germ layers during gastrulation. Studies of gastrulation in Drosophila have provided insight into how epithelial morphogenesis is governed by developmental patterning mechanisms. We developed an assay to recapitulate morphogenetic shape changes in individual cultured cells and used RNA interference-based screening to identify Mist, a Drosophila G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) that transduces signals from the secreted ligand Folded gastrulation (Fog) in cultured cells. Mist functioned in Fog-dependent embryonic morphogenesis, and the transcription factor Snail regulated expression of mist in zygotes. Our data revealed how a cell fate transcriptional program acts through a ligand-GPCR pair to stimulate epithelial morphogenetic shape changes.
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Affiliation(s)
- Alyssa J Manning
- 1Department of Biology, University of North Carolina at Chapel Hill, CB# 3280, Fordham Hall, South Road, Chapel Hill, NC 27599-3280, USA
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30
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Krajcovic MM, Minden JS. Assessing the critical period for Rho kinase activity during Drosophila ventral furrow formation. Dev Dyn 2012; 241:1729-43. [PMID: 22972587 DOI: 10.1002/dvdy.23859] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2012] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Drosophila ventral furrow formation (VFF), which is the first morphogenetic event during embryo development, serves as a model for epithelial sheet folding. VFF can be subdivided into five cell shape changes: apical membrane flattening, apicobasal nuclear migration, apicobasal cell shortening, random apical constriction, and concerted apical constriction. These processes are generally believed to be driven by Rho kinase (Rok) activation of myosin II to stimulate the constriction of the apical actomyosin network. To test the role of Rok and its downstream target myosin II in VFF, timed injections of the Rok inhibitor, Y-27632, were performed. RESULTS Embryos injected with Y-27632 before the concerted apical constriction phase of VFF were able to execute apicobasal nuclear migration and random apical constriction, but were unable to enter the concerted apical constriction phase. Embryos injected with Y-27632 during concerted apical constriction reverted to the transition point between random apical constriction and concerted apical constriction. Finally, embryos injected with Y-27632 upon the initiation of furrow ingression were able to complete VFF. CONCLUSIONS Together these results suggest a critical period for Rok activity and presumably myosin II activation during the initiation of the concerted apical constriction phase of VFF.
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Affiliation(s)
- Melissa M Krajcovic
- Carnegie Mellon University, Department of Biological Sciences, Pittsburgh, PA 15213, USA
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Mammoto A, Mammoto T, Ingber DE. Mechanosensitive mechanisms in transcriptional regulation. J Cell Sci 2012; 125:3061-73. [PMID: 22797927 DOI: 10.1242/jcs.093005] [Citation(s) in RCA: 282] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Transcriptional regulation contributes to the maintenance of pluripotency, self-renewal and differentiation in embryonic cells and in stem cells. Therefore, control of gene expression at the level of transcription is crucial for embryonic development, as well as for organogenesis, functional adaptation, and regeneration in adult tissues and organs. In the past, most work has focused on how transcriptional regulation results from the complex interplay between chemical cues, adhesion signals, transcription factors and their co-regulators during development. However, chemical signaling alone is not sufficient to explain how three-dimensional (3D) tissues and organs are constructed and maintained through the spatiotemporal control of transcriptional activities. Accumulated evidence indicates that mechanical cues, which include physical forces (e.g. tension, compression or shear stress), alterations in extracellular matrix (ECM) mechanics and changes in cell shape, are transmitted to the nucleus directly or indirectly to orchestrate transcriptional activities that are crucial for embryogenesis and organogenesis. In this Commentary, we review how the mechanical control of gene transcription contributes to the maintenance of pluripotency, determination of cell fate, pattern formation and organogenesis, as well as how it is involved in the control of cell and tissue function throughout embryogenesis and adult life. A deeper understanding of these mechanosensitive transcriptional control mechanisms should lead to new approaches to tissue engineering and regenerative medicine.
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Affiliation(s)
- Akiko Mammoto
- Vascular Biology Program, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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32
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Spahn P, Ott A, Reuter R. The PDZ-GEF protein Dizzy regulates the establishment of adherens junctions required for ventral furrow formation in Drosophila. J Cell Sci 2012; 125:3801-12. [PMID: 22553205 DOI: 10.1242/jcs.101196] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The PDZ-GEF protein Dizzy (Dzy) and its downstream GTPase Rap1 have pleiotropic roles during development of the Drosophila embryo. Here, we show that maternally provided Dzy and Rap1 first function during ventral furrow formation (VFF) where they are critical to guarantee rapid apical cell constrictions. Contraction of the apical actomyosin filament system occurs independently of Dzy and Rap1, but loss of Dzy results in a delayed establishment of the apical adherens junction (AJ) belt, whereas in the absence of Rap1 only a fragmentary apical AJ belt is formed in the epithelium. The timely establishment of apical AJs appears to be essential for coupling actomyosin contractions to cell shape change and to assure completion of the ventral furrow. Immediately after VFF, the downregulation of Dzy and Rap1 is necessary to allow normal mesodermal development to continue after the epithelial-to-mesenchymal transition, as overexpression of Dzy or of constitutively active Rap1 compromises mesodermal migration and monolayer formation. We propose that Dzy and Rap1 are crucial factors regulating the dynamics of AJs during gastrulation.
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Affiliation(s)
- Philipp Spahn
- Interfakultäres Institut für Zellbiologie, Abteilung Genetik der Tiere, Fachbereich für Biologie, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
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33
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Driquez B, Bouclet A, Farge E. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation. Phys Biol 2011; 8:066007. [PMID: 22120059 DOI: 10.1088/1478-3975/8/6/066007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular mesoderm invagination.
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Affiliation(s)
- Benjamin Driquez
- Mechanics and Genetics of Embryonic and Tumoral Development Group, Institut Curie, Paris, France
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Role for Traf4 in polarizing adherens junctions as a prerequisite for efficient cell shape changes. Mol Cell Biol 2011; 31:4978-93. [PMID: 21986496 DOI: 10.1128/mcb.05542-11] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Apical constriction of epithelial cells is a widely used morphogenetic mechanism. In the Drosophila embryo, the apical constrictions that internalize the mesoderm are controlled by the transcription factor Twist and require intact adherens junctions and a contractile acto-myosin network. We find that adherens junctions in constricting mesodermal cells undergo extensive remodeling. A Twist target gene encoding a member of the tumor necrosis factor (TNF) receptor-associated factor (TRAF) family, Traf4, is involved in this process. While TRAFs are best known for their functions in inflammatory responses, Traf4 appears to have a different role, and its mechanism of action is poorly understood. We show that Traf4 is required for efficient apical constriction during ventral furrow formation and for proper localization of Armadillo to the apical position in constricting cells. Traf4 and Armadillo interact with each other physically and functionally. Traf4 acts in a TNF receptor- and Jun N-terminal protein kinase (JNK)-independent manner to fine-tune the assembly of adherens junctions in the invaginating mesodermal cells.
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35
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Lander R, Nordin K, LaBonne C. The F-box protein Ppa is a common regulator of core EMT factors Twist, Snail, Slug, and Sip1. ACTA ACUST UNITED AC 2011; 194:17-25. [PMID: 21727196 PMCID: PMC3135407 DOI: 10.1083/jcb.201012085] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The core EMT regulatory factors Twist, Snail, Slug, and Sip1, while structurally diverse, are coordinately regulated by a common E3 ubiquiting ligase, Ppa. A small group of core transcription factors, including Twist, Snail, Slug, and Sip1, control epithelial–mesenchymal transitions (EMTs) during both embryonic development and tumor metastasis. However, little is known about how these factors are coordinately regulated to mediate the requisite behavioral and fate changes. It was recently shown that a key mechanism for regulating Snail proteins is by modulating their stability. In this paper, we report that the stability of Twist is also regulated by the ubiquitin–proteasome system. We found that the same E3 ubiquitin ligase known to regulate Snail family proteins, Partner of paired (Ppa), also controlled Twist stability and did so in a manner dependent on the Twist WR-rich domain. Surprisingly, Ppa could also target the third core EMT regulatory factor Sip1 for proteasomal degradation. Together, these results indicate that despite the structural diversity of the core transcriptional regulatory factors implicated in EMT, a common mechanism has evolved for controlling their stability and therefore their function.
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Affiliation(s)
- Rachel Lander
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
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36
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Abstract
During morphogenesis, tissues are shaped by cell behaviors such as apical cell constriction and cell intercalation, which are the result of cell intrinsic forces, but are also shaped passively by forces acting on the cells. The latter extrinsic forces can be produced either within the deforming tissue by the tissue-scale integration of intrinsic forces, or outside the tissue by other tissue movements or by fluid flows. Here we review the intrinsic and extrinsic forces that sculpt the epithelium of early Drosophila embryos, focusing on three conserved morphogenetic processes: tissue internalization, axis extension, and segment boundary formation. Finally, we look at how the actomyosin cytoskeleton forms force-generating structures that power these three morphogenetic events at the cell and the tissue scales.
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37
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Abstract
Biochemical patterning and morphogenetic movements coordinate the design of embryonic development. The molecular processes that pattern and closely control morphogenetic movements are today becoming well understood. Recent experimental evidence demonstrates that mechanical cues generated by morphogenesis activate mechanotransduction pathways, which in turn regulate cytoskeleton remodeling, cell proliferation, tissue differentiation. From Drosophila oocytes and embryos to Xenopus and mouse embryos and Arabidopsis meristem, here we review the developmental processes known to be activated in vivo by the mechanical strains associated to embryonic multicellular tissue morphogenesis. We describe the genetic, mechanical, and magnetic tools that have allowed the testing of mechanical induction in development by a step-by-step uncoupling of genetic inputs from mechanical inputs in embryogenesis. We discuss the known underlying molecular mechanisms involved in such mechanotransduction processes, including the Armadillo/β-catenin activation of Twist and the Fog-dependent stabilization of Myosin-II. These mechanotransduction processes are associated with a variety of physiological functions, such as mid-gut differentiation, mesoderm invagination and skeletal joint differentiation in embryogenesis, cell migration and internal pressure regulation during oogenesis, and meristem morphogenesis. We describe how the conservation of associated mechanosensitive pathways in embryonic and adult tissues opens new perspectives on mechanical involvement, potentially in evolution, and in cancer progression.
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Affiliation(s)
- Emmanuel Farge
- Mechanics and Genetics of Embryonic and Tumoral Development Group, UMR168 CNRS, Institut Curie, Paris, France
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38
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A new resource for characterizing X-linked genes in Drosophila melanogaster: systematic coverage and subdivision of the X chromosome with nested, Y-linked duplications. Genetics 2010; 186:1095-109. [PMID: 20876560 DOI: 10.1534/genetics.110.123265] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Interchromosomal duplications are especially important for the study of X-linked genes. Males inheriting a mutation in a vital X-linked gene cannot survive unless there is a wild-type copy of the gene duplicated elsewhere in the genome. Rescuing the lethality of an X-linked mutation with a duplication allows the mutation to be used experimentally in complementation tests and other genetic crosses and it maps the mutated gene to a defined chromosomal region. Duplications can also be used to screen for dosage-dependent enhancers and suppressors of mutant phenotypes as a way to identify genes involved in the same biological process. We describe an ongoing project in Drosophila melanogaster to generate comprehensive coverage and extensive breakpoint subdivision of the X chromosome with megabase-scale X segments borne on Y chromosomes. The in vivo method involves the creation of X inversions on attached-XY chromosomes by FLP-FRT site-specific recombination technology followed by irradiation to induce large internal X deletions. The resulting chromosomes consist of the X tip, a medial X segment placed near the tip by an inversion, and a full Y. A nested set of medial duplicated segments is derived from each inversion precursor. We have constructed a set of inversions on attached-XY chromosomes that enable us to isolate nested duplicated segments from all X regions. To date, our screens have provided a minimum of 78% X coverage with duplication breakpoints spaced a median of nine genes apart. These duplication chromosomes will be valuable resources for rescuing and mapping X-linked mutations and identifying dosage-dependent modifiers of mutant phenotypes.
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39
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McMahon A, Reeves GT, Supatto W, Stathopoulos A. Mesoderm migration in Drosophila is a multi-step process requiring FGF signaling and integrin activity. Development 2010; 137:2167-75. [PMID: 20530544 DOI: 10.1242/dev.051573] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Migration is a complex, dynamic process that has largely been studied using qualitative or static approaches. As technology has improved, we can now take quantitative approaches towards understanding cell migration using in vivo imaging and tracking analyses. In this manner, we have established a four-step model of mesoderm migration during Drosophila gastrulation: (I) mesodermal tube formation, (II) collapse of the mesoderm, (III) dorsal migration and spreading and (IV) monolayer formation. Our data provide evidence that these steps are temporally distinct and that each might require different chemical inputs. To support this, we analyzed the role of fibroblast growth factor (FGF) signaling, in particular the function of two Drosophila FGF ligands, Pyramus and Thisbe, during mesoderm migration. We determined that FGF signaling through both ligands controls movements in the radial direction. Thisbe is required for the initial collapse of the mesoderm onto the ectoderm, whereas both Pyramus and Thisbe are required for monolayer formation. In addition, we uncovered that the GTPase Rap1 regulates radial movement of cells and localization of the beta-integrin subunit, Myospheroid, which is also required for monolayer formation. Our analyses suggest that distinct signals influence particular movements, as we found that FGF signaling is involved in controlling collapse and monolayer formation but not dorsal movement, whereas integrins are required to support monolayer formation only and not earlier movements. Our work demonstrates that complex cell migration is not necessarily a fluid process, but suggests instead that different types of movements are directed by distinct inputs in a stepwise manner.
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Affiliation(s)
- Amy McMahon
- California Institute of Technology, Division of Biology MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
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40
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Abstract
Many genes and molecules that drive tissue patterning during organogenesis and tissue regeneration have been discovered. Yet, we still lack a full understanding of how these chemical cues induce the formation of living tissues with their unique shapes and material properties. Here, we review work based on the convergence of physics, engineering and biology that suggests that mechanical forces generated by living cells are as crucial as genes and chemical signals for the control of embryological development, morphogenesis and tissue patterning.
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Affiliation(s)
- Tadanori Mammoto
- Vascular Biology Program, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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41
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Zimmerman SG, Thorpe LM, Medrano VR, Mallozzi CA, McCartney BM. Apical constriction and invagination downstream of the canonical Wnt signaling pathway require Rho1 and Myosin II. Dev Biol 2010; 340:54-66. [PMID: 20102708 DOI: 10.1016/j.ydbio.2010.01.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/13/2010] [Accepted: 01/18/2010] [Indexed: 12/12/2022]
Abstract
The tumor suppressor Adenomatous polyposis coli (APC) is a negative regulator of Wnt signaling and functions in cytoskeletal organization. Disruption of human APC in colonic epithelia initiates benign polyps that progress to carcinoma following additional mutations. The early events of polyposis are poorly understood, as is the role of canonical Wnt signaling in normal epithelial architecture and morphogenesis. To determine the consequences of complete loss of APC in a model epithelium, we generated APC2 APC1 double null clones in the Drosophila wing imaginal disc. APC loss leads to segregation, apical constriction, and invagination that result from transcriptional activation of canonical Wnt signaling. Further, we show that Wnt-dependent changes in cell fate can be decoupled from Wnt-dependent changes in cell shape. Wnt activation is reported to upregulate DE-cadherin in wing discs, and elevated DE-cadherin is thought to promote apical constriction. We find that apical constriction and invagination of APC null tissue are independent of DE-cadherin elevation, but are dependent on Myosin II activity. Further, we show that disruption of Rho1 suppresses apical constriction and invagination in APC null cells. Our data suggest a novel link between canonical Wnt signaling and epithelial structure that requires activation of the Rho1 pathway and Myosin II.
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Affiliation(s)
- Sandra G Zimmerman
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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42
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Fernandez-Sanchez ME, Serman F, Ahmadi P, Farge E. Mechanical induction in embryonic development and tumor growth integrative cues through molecular to multicellular interplay and evolutionary perspectives. Methods Cell Biol 2010; 98:295-321. [PMID: 20816239 DOI: 10.1016/s0091-679x(10)98012-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Embryonic development is a coordination of multicellular biochemical patterning and morphogenetic movements. Last decades revealed the close control of myosin-II-dependent biomechanical morphogenesis by patterning gene expression, with constant progress in the understanding of the underlying molecular mechanisms. Reversed control of developmental gene expression and of myosin-II patterning by the mechanical strains developed by morphogenetic movements was recently revealed at Drosophila gastrulation, through mechanotransduction processes involving the Armadillo/beta-catenin and the downstream of Fog Rho pathways. Here, we present the theoretical (simulations integrating the accumulated knowledge in the genetics of early embryonic development and morphogenesis) and the experimental (genetic and biophysical control of morphogenetic movements) tools having allowed the uncoupling of pure genetic inputs from pure mechanical inputs in the regulation of gene expression and myosin-II patterning. Specifically, we describe the innovative magnetic tweezers tools we have set up to measure and apply physiological strains and forces in vivo, from the inside of the tissue, to modulate and mimic morphogenetic movements in living embryos. We discuss mechanical induction incidence in tumor development and perspective in evolution.
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Affiliation(s)
- Maria-Elena Fernandez-Sanchez
- Mechanics and Genetics of Embryonic and Tumoral Development group, UMR168 CNRS, Institut Curie, 11 rue Pierre et Marie Curie, F-75005, Paris, France
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43
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Mathew SJ, Kerridge S, Leptin M. A small genomic region containing several loci required for gastrulation in Drosophila. PLoS One 2009; 4:e7437. [PMID: 19823683 PMCID: PMC2758545 DOI: 10.1371/journal.pone.0007437] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 09/07/2009] [Indexed: 01/26/2023] Open
Abstract
Genetic screens in Drosophila designed to search for loci involved in gastrulation have identified four regions of the genome that are required zygotically for the formation of the ventral furrow. For three of these, the genes responsible for the mutant phenotypes have been found. We now describe a genetic characterization of the fourth region, which encompasses the cytogenetic interval 24C3-25B, and the mapping of genes involved in gastrulation in this region. We have determined the precise breakpoints of several existing deficiencies and have generated new deficiencies. Our results show that the region contains at least three different loci associated with gastrulation effects. One maternal effect gene involved in ventral furrow formation maps at 24F but could not be identified. For a second maternal effect gene which is required for germ band extension, we identify a candidate gene, CG31660, which encodes a G protein coupled receptor. Finally, one gene acts zygotically in ventral furrow formation and we identify it as Traf4.
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Affiliation(s)
- Sam J. Mathew
- Institute of Genetics, University of Cologne, Cologne, Germany
| | - Stephen Kerridge
- IBDML-UMR6216, Case 907 Parc Scientifique de Luminy, Marseille, France
| | - Maria Leptin
- Institute of Genetics, University of Cologne, Cologne, Germany
- * E-mail:
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44
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Zhang C, Klymkowsky MW. Unexpected functional redundancy between Twist and Slug (Snail2) and their feedback regulation of NF-kappaB via Nodal and Cerberus. Dev Biol 2009; 331:340-9. [PMID: 19389392 PMCID: PMC2747320 DOI: 10.1016/j.ydbio.2009.04.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 04/08/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
Abstract
A NF-kappaB-Twist-Snail network controls axis and mesoderm formation in Drosophila. Using translation-blocking morpholinos and hormone-regulated proteins, we demonstrate the presence of an analogous network in the early Xenopus embryo. Loss of twist (twist1) function leads to a reduction of mesoderm and neural crest markers, an increase in apoptosis, and a decrease in snail1 (snail) and snail2 (slug) mRNA levels. Injection of snail2 mRNA rescues twist's loss of function phenotypes and visa versa. In the early embryo NF-kappaB/RelA regulates twist, snail2, and snail1 mRNA levels; similarly Nodal/Smad2 regulate twist, snail2, snail1, and relA RNA levels. Both Twist and Snail2 negatively regulate levels of cerberus RNA, which encodes a Nodal, bone morphogenic protein (BMP), and Wnt inhibitor. Cerberus's anti-Nodal activity inhibits NF-kappaB activity and decreases relA RNA levels. These results reveal both conserved and unexpected regulatory interactions at the core of a vertebrate's mesodermal specification network.
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Affiliation(s)
| | - Michael W. Klymkowsky
- Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Boulder, CO 80309-0347, U.S.A
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45
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Butler LC, Blanchard GB, Kabla AJ, Lawrence NJ, Welchman DP, Mahadevan L, Adams RJ, Sanson B. Cell shape changes indicate a role for extrinsic tensile forces in Drosophila germ-band extension. Nat Cell Biol 2009; 11:859-64. [DOI: 10.1038/ncb1894] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 04/28/2009] [Indexed: 02/04/2023]
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46
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Pouille PA, Ahmadi P, Brunet AC, Farge E. Mechanical signals trigger Myosin II redistribution and mesoderm invagination in Drosophila embryos. Sci Signal 2009; 2:ra16. [PMID: 19366994 DOI: 10.1126/scisignal.2000098] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
During Drosophila gastrulation, two waves of constriction occur in the apical ventral cells, leading to mesoderm invagination. The first constriction wave is a stochastic process mediated by the constriction of 40% of randomly positioned mesodermal cells and is controlled by the transcription factor Snail. The second constriction wave immediately follows and involves the other 60% of the mesodermal cells. The second wave is controlled by the transcription factor Twist and requires the secreted protein Fog. Complete mesoderm invagination requires redistribution of the motor protein Myosin II to the apical side of the constricting cells. We show that apical redistribution of Myosin II and mesoderm invagination, both of which are impaired in snail homozygous mutants that are defective in both constriction waves, are rescued by local mechanical deformation of the mesoderm with a micromanipulated needle. Mechanical deformation appears to promote Fog-dependent signaling by inhibiting Fog endocytosis. We propose that the mechanical tissue deformation that occurs during the Snail-dependent stochastic phase is necessary for the Fog-dependent signaling that mediates the second collective constriction wave.
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Conte V, Muñoz JJ, Baum B, Miodownik M. Robust mechanisms of ventral furrow invagination require the combination of cellular shape changes. Phys Biol 2009; 6:016010. [PMID: 19342769 DOI: 10.1088/1478-3975/6/1/016010] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ventral furrow formation in Drosophila is the first large-scale morphogenetic movement during the life of the embryo, and is driven by co-ordinated changes in the shape of individual epithelial cells within the cellular blastoderm. Although many of the genes involved have been identified, the details of the mechanical processes that convert local changes in gene expression into whole-scale changes in embryonic form remain to be fully understood. Biologists have identified two main cell deformation modes responsible for ventral furrow invagination: constriction of the apical ends of the cells (apical wedging) and deformation along their apical-basal axes (radial lengthening/shortening). In this work, we used a computer 2D finite element model of ventral furrow formation to investigate the ability of different combinations of three plausible elementary active cell shape changes to bring about epithelial invagination: ectodermal apical-basal shortening, mesodermal apical-basal lengthening/shortening and mesodermal apical constriction. We undertook a systems analysis of the biomechanical system, which revealed many different combinations of active forces (invagination mechanisms) were able to generate a ventral furrow. Two important general features were revealed. First that combinations of shape changes are the most robust to environmental and mutational perturbation, in particular those combining ectodermal pushing and mesodermal wedging. Second, that ectodermal pushing plays a big part in all of the robust mechanisms (mesodermal forces alone do not close the furrow), and this provides evidence that it may be an important element in the mechanics of invagination in Drosophila.
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Affiliation(s)
- Vito Conte
- Materials Research Group, Division of Engineering, King's College London, UK
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48
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van Impel A, Schumacher S, Draga M, Herz HM, Grosshans J, Müller HAJ. Regulation of the Rac GTPase pathway by the multifunctional Rho GEF Pebble is essential for mesoderm migration in the Drosophila gastrula. Development 2009; 136:813-22. [PMID: 19176590 PMCID: PMC2685947 DOI: 10.1242/dev.026203] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2009] [Indexed: 01/09/2023]
Abstract
The Drosophila guanine nucleotide exchange factor Pebble (Pbl) is essential for cytokinesis and cell migration during gastrulation. In dividing cells, Pbl promotes Rho1 activation at the cell cortex, leading to formation of the contractile actin-myosin ring. The role of Pbl in fibroblast growth factor-triggered mesoderm spreading during gastrulation is less well understood and its targets and subcellular localization are unknown. To address these issues we performed a domain-function study in the embryo. We show that Pbl is localized to the nucleus and the cell cortex in migrating mesoderm cells and found that, in addition to the PH domain, the conserved C-terminal tail of the protein is crucial for cortical localization. Moreover, we show that the Rac pathway plays an essential role during mesoderm migration. Genetic and biochemical interactions indicate that during mesoderm migration, Pbl functions by activating a Rac-dependent pathway. Furthermore, gain-of-function and rescue experiments suggest an important regulatory role of the C-terminal tail of Pbl for the selective activation of Rho1-versus Rac-dependent pathways.
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Affiliation(s)
- Andreas van Impel
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, UK
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49
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Paluch E, Heisenberg CP. Chaos Begets Order: Asynchronous Cell Contractions Drive Epithelial Morphogenesis. Dev Cell 2009; 16:4-6. [DOI: 10.1016/j.devcel.2008.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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BARNES RALSTONM, FIRULLI ANTHONYB. A twist of insight - the role of Twist-family bHLH factors in development. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2009; 53:909-24. [PMID: 19378251 PMCID: PMC2737731 DOI: 10.1387/ijdb.082747rb] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Members of the Twist-family of bHLH proteins play a pivotal role in a number of essential developmental programs. Twist-family bHLH proteins function by dimerizing with other bHLH members and binding to cis- regulatory elements, called E-boxes. While Twist-family members may simply exhibit a preference in terms of high-affinity binding partners, a complex, multilevel cascade of regulation creates a dynamic role for these bHLH proteins. We summarize in this review information on each Twist-family member concerning expression pattern, function, regulation, downstream targets, and interactions with other bHLH proteins. Additionally, we focus on the phospho-regulatory mechanisms that tightly control posttranslational modification of Twist-family member bHLH proteins.
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Affiliation(s)
- RALSTON M. BARNES
- Riley Heart Research Center, Wells Center for Pediatric Research, Division of Pediatric Cardiology, Departments of Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN, USA
| | - ANTHONY B. FIRULLI
- Riley Heart Research Center, Wells Center for Pediatric Research, Division of Pediatric Cardiology, Departments of Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN, USA
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