151
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Aliee M, Röper JC, Landsberg KP, Pentzold C, Widmann TJ, Jülicher F, Dahmann C. Physical mechanisms shaping the Drosophila dorsoventral compartment boundary. Curr Biol 2012; 22:967-76. [PMID: 22560616 DOI: 10.1016/j.cub.2012.03.070] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/28/2012] [Accepted: 03/27/2012] [Indexed: 11/27/2022]
Abstract
BACKGROUND Separating cells with distinct identities and fates by straight and sharp compartment boundaries is important for growth and pattern formation during animal development. The physical mechanisms shaping compartment boundaries, however, are not fully understood. RESULTS We combine theory and quantitative experiments to investigate the roles of different mechanisms to shape compartment boundaries. Our theoretical work shows that cell elongation created by anisotropic stress, cell proliferation rate, orientation of cell division, and cell bond tension all have distinct effects on the morphology of compartment boundaries during tissue growth. Our experiments using the developing Drosophila wing reveal that the roughness of the dorsoventral compartment boundary is dynamic and that it decreases during development. By measuring tissue relaxation in response to laser ablation of cell bonds at different developmental times, we demonstrate that decreased boundary roughness correlates with increased cell bond tension along the compartment boundary. Finally, by using experimentally determined values for cell bond tension, cell elongation and bias in orientation of cell division in simulations of tissue growth, we can reproduce the main features of the time evolution of the dorsoventral compartment boundary shape. CONCLUSIONS Local increase of cell bond tension along the boundary as well as global anisotropies in the tissue contribute to shaping boundaries in cell networks. We propose a simple scenario that combines time-dependent cell bond tension at the boundary, oriented cell division, and cell elongation in the tissue that can account for the main features of the dynamics of the shape of the dorsoventral compartment boundary.
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Affiliation(s)
- Maryam Aliee
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Strasse 38, 01187 Dresden, Germany
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152
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Abstract
The ramified architectures of organs such as the mammary gland and lung are generated via branching morphogenesis, a developmental process through which individual cells bud and pinch off of pre-existing epithelial sheets. Although specified by signaling programs, organ development requires integration of all aspects of the microenvironment. We describe the essential role of endogenous cellular contractility in the formation of branching tubes. We also highlight the role of exogenous forces in normal and aberrant branching.
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Affiliation(s)
- Celeste M Nelson
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA.
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153
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Batlle E, Wilkinson DG. Molecular mechanisms of cell segregation and boundary formation in development and tumorigenesis. Cold Spring Harb Perspect Biol 2012; 4:a008227. [PMID: 22214769 PMCID: PMC3249626 DOI: 10.1101/cshperspect.a008227] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The establishment and maintenance of precisely organized tissues requires the formation of sharp borders between distinct cell populations. The maintenance of segregated cell populations is also required for tissue homeostasis in the adult, and deficiencies in segregation underlie the metastatic spreading of tumor cells. Three classes of mechanisms that underlie cell segregation and border formation have been uncovered. The first involves differences in cadherin-mediated cell-cell adhesion that establishes interfacial tension at the border between distinct cell populations. A second mechanism involves the induction of actomyosin-mediated contraction by intercellular signaling, such that cortical tension is generated at the border. Third, activation of Eph receptors and ephrins can lead to both decreased adhesion by triggering cleavage of E-cadherin, and to repulsion of cells by regulation of the actin cytoskeleton, thus preventing intermingling between cell populations. These mechanisms play crucial roles at distinct boundaries during development, and alterations in cadherin or Eph/ephrin expression have been implicated in tumor metastasis.
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Affiliation(s)
- Eduard Batlle
- Oncology Program and ICREA, Institute for Research in Biomedicine, Josep Samitier 1-5, 08028 Barcelona, Spain
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154
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Harris TJ. Adherens Junction Assembly and Function in the Drosophila Embryo. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 293:45-83. [DOI: 10.1016/b978-0-12-394304-0.00007-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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155
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Cytokinesis remnants define first neuronal asymmetry in vivo. Nat Neurosci 2011; 14:1525-33. [DOI: 10.1038/nn.2976] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/08/2011] [Indexed: 01/22/2023]
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156
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Li X, Kapoor TM. An optical switch for a motor protein. Chembiochem 2011; 12:2265-6. [PMID: 23106075 DOI: 10.1002/cbic.201100439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Light-triggered motor: Incorporation of a photocleavable group onto a phosphoserine residue of the regulator of a motor protein allows light-induced activation with spatial and temporal precision inside a living cell.
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Affiliation(s)
- Xiang Li
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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157
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Kanesaki T, Edwards CM, Schwarz US, Grosshans J. Dynamic ordering of nuclei in syncytial embryos: a quantitative analysis of the role of cytoskeletal networks. Integr Biol (Camb) 2011; 3:1112-9. [PMID: 22001900 DOI: 10.1039/c1ib00059d] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In syncytial embryos nuclei undergo cycles of division and rearrangement within a common cytoplasm. It is presently unclear to what degree and how the nuclear array maintains positional order in the face of rapid cell divisions. Here we establish a quantitative assay, based on image processing, for analysing the dynamics of the nuclear array. By tracking nuclear trajectories in Drosophila melanogaster embryos, we are able to define and evaluate local and time-dependent measures for the level of geometrical order in the array. We find that after division, order is re-established in a biphasic manner, indicating the competition of different ordering processes. Using mutants and drug injections, we show that the order of the nuclear array depends on cytoskeletal networks organised by centrosomes. While both f-actin and microtubules are required for re-establishing order after mitosis, only f-actin is required to maintain the stability of this arrangement. Furthermore, f-actin function relies on myosin-independent non-contractile filaments that suppress individual nuclear mobility, whereas microtubules promote mobility and attract adjacent nuclei. Actin caps are shown to act to prevent nuclear incorporation into adjacent microtubule baskets. Our data demonstrate that two principal ordering mechanisms thus simultaneously contribute: (1) a passive crowding mechanism in which nuclei and actin caps act as spacers and (2) an active self-organisation mechanism based on a microtubule network.
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Affiliation(s)
- Takuma Kanesaki
- Institute for Biochemistry, Medical School, University of Göttingen, 37077 Göttingen, Germany
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158
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St Johnston D, Sanson B. Epithelial polarity and morphogenesis. Curr Opin Cell Biol 2011; 23:540-6. [PMID: 21807488 DOI: 10.1016/j.ceb.2011.07.005] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 07/07/2011] [Accepted: 07/07/2011] [Indexed: 12/19/2022]
Affiliation(s)
- Daniel St Johnston
- The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Rd, Cambridge CB2 1QN, United Kingdom.
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159
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Vichas A, Zallen JA. Translating cell polarity into tissue elongation. Semin Cell Dev Biol 2011; 22:858-64. [PMID: 21983030 PMCID: PMC4752253 DOI: 10.1016/j.semcdb.2011.09.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 09/23/2011] [Accepted: 09/23/2011] [Indexed: 10/17/2022]
Abstract
Planar cell polarity, the orientation of single-cell asymmetries within the plane of a multicellular tissue, is essential to generating the shape and dimensions of organs and organisms. Planar polarity systems align cell behavior with the body axes and orient the cellular processes that lead to tissue elongation. Using Drosophila as a model system, significant progress has been made toward understanding how planar polarity is generated by biochemical and mechanical signals. Recent studies using time-lapse imaging reveal that cells engage in a number of active behaviors whose orientation and dynamics translate planar cell polarity into tissue elongation. Here we review recent progress in understanding the cellular mechanisms that link planar polarity to large-scale changes in tissue structure.
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Affiliation(s)
- Athea Vichas
- Howard Hughes Medical Institute, Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
| | - Jennifer A. Zallen
- Howard Hughes Medical Institute, Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
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160
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Canela-Xandri O, Sagués F, Casademunt J, Buceta J. Dynamics and mechanical stability of the developing dorsoventral organizer of the wing imaginal disc. PLoS Comput Biol 2011; 7:e1002153. [PMID: 21980267 PMCID: PMC3182857 DOI: 10.1371/journal.pcbi.1002153] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 06/20/2011] [Indexed: 01/26/2023] Open
Abstract
Shaping the primordia during development relies on forces and mechanisms able to control cell segregation. In the imaginal discs of Drosophila the cellular populations that will give rise to the dorsal and ventral parts on the wing blade are segregated and do not intermingle. A cellular population that becomes specified by the boundary of the dorsal and ventral cellular domains, the so-called organizer, controls this process. In this paper we study the dynamics and stability of the dorsal-ventral organizer of the wing imaginal disc of Drosophila as cell proliferation advances. Our approach is based on a vertex model to perform in silico experiments that are fully dynamical and take into account the available experimental data such as: cell packing properties, orientation of the cellular divisions, response upon membrane ablation, and robustness to mechanical perturbations induced by fast growing clones. Our results shed light on the complex interplay between the cytoskeleton mechanics, the cell cycle, the cell growth, and the cellular interactions in order to shape the dorsal-ventral organizer as a robust source of positional information and a lineage controller. Specifically, we elucidate the necessary and sufficient ingredients that enforce its functionality: distinctive mechanical properties, including increased tension, longer cell cycle duration, and a cleavage criterion that satisfies the Hertwig rule. Our results provide novel insights into the developmental mechanisms that drive the dynamics of the DV organizer and set a definition of the so-called Notch fence model in quantitative terms. During development, tissues are shaped in order to form organs with specific functionalities. This process relies on mechanisms that control cell segregation and migration. These concepts are beautifully illustrated by the morphogenetic events that the imaginal discs of Drosophila undergo during metamorphosis. In particular, the cellular populations that will give rise to the dorsal (D) and ventral (V) parts on the wing blade are segregated and do not intermingle. The so-called organizer, a cellular population that becomes specified by the boundary of the D and V cellular domains, is responsible for this. Yet, how does the DV organizer robustly deal with the cellular growth in order to prevent cell mixing? Moreover, how can the organizer be conveniently scaled as the tissue grows? Herein we address these questions using a computational approach that takes into account the available experimental data. Thus, our study unveils the elements that are necessary and sufficient for understanding in a quantitative and predictive manner the dynamics, structure, and stability of a robust growing DV organizer: distinctive mechanical properties of cells, differences in cell cycle duration, and a well-defined cleavage criterion.
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Affiliation(s)
- Oriol Canela-Xandri
- Computer Simulation and Modeling (Co.S.Mo.) Lab, Parc Científic de Barcelona, Barcelona, Spain
- Departament d'Estructura i Constituents de la Matèria, Universitat de Barcelona, Barcelona, Spain
| | - Francesc Sagués
- Departament de Química-Física, Universitat de Barcelona, Barcelona, Spain
| | - Jaume Casademunt
- Departament d'Estructura i Constituents de la Matèria, Universitat de Barcelona, Barcelona, Spain
| | - Javier Buceta
- Computer Simulation and Modeling (Co.S.Mo.) Lab, Parc Científic de Barcelona, Barcelona, Spain
- * E-mail:
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161
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Quantitative microscopy and imaging tools for the mechanical analysis of morphogenesis. Curr Opin Genet Dev 2011; 21:664-70. [PMID: 21893407 DOI: 10.1016/j.gde.2011.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 11/20/2022]
Abstract
The importance of mechanical signals during embryogenesis and development, through both intercellular and extracellular signals, is coming into focus. It is widely hypothesized that physical forces help to guide the shape, cellular differentiation and the patterning of tissues. To test these ideas many classical engineering principles and imaging technologies are being adapted. Recent advances in microscopy, mechanical testing and genetic and pharmacological techniques, alongside computational models are helping to dissect the activity of mechanical signals in development at the cellular and molecular level. These inroads are providing maps of mechanical changes in tissue structure and stiffness, and will permit deeper insights into the role of mechanics in both developmental biology and disease.
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162
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Mason FM, Martin AC. Tuning cell shape change with contractile ratchets. Curr Opin Genet Dev 2011; 21:671-9. [PMID: 21893409 DOI: 10.1016/j.gde.2011.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 08/03/2011] [Accepted: 08/10/2011] [Indexed: 11/15/2022]
Abstract
Throughout the lifespan of an organism, shape changes are necessary for cells to carry out their essential functions. Nowhere is this more dramatic than embryonic development and gastrulation, when cell shape changes drive large-scale rearrangements in tissue architecture to establish the body plan of the organism. A longstanding question for both cell and developmental biologists has been how are forces generated to change cell shape? Recent studies in both cell culture and developing embryos have combined live imaging, computational analysis, genetics, and biophysics to identify ratchet-like behaviors in actomyosin networks that operate to incrementally change cell shape, drive cell movement, and deform tissues. Our analysis of several cell shape changes leads us to propose four regulatory modules associated with ratchet-like deformations that are tuned to generate diverse cell behaviors, coordinating cell shape change across a tissue.
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Affiliation(s)
- Frank M Mason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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163
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Leckband DE, le Duc Q, Wang N, de Rooij J. Mechanotransduction at cadherin-mediated adhesions. Curr Opin Cell Biol 2011; 23:523-30. [PMID: 21890337 DOI: 10.1016/j.ceb.2011.08.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 07/21/2011] [Accepted: 08/08/2011] [Indexed: 01/30/2023]
Abstract
Cell-to-cell junctions are crucial mechanical and signaling hubs that connect cells within tissues and probe the mechanics of the surrounding environment. Although the capacity of cell-to-extracellular-matrix (ECM) adhesions to sense matrix mechanics and proportionally modify cell functions is well established, cell-cell adhesions only recently emerged as a new class of force sensors. This finding exposes new pathways through which force can instruct cell functions. This review highlights recent findings, which demonstrate that protein complexes associated with classical cadherins, the principal architectural proteins at cell-cell junctions in all soft tissues, are mechanosensors. We further discuss the current understanding of the rudiments of a cadherin-based mechanosensing and transduction pathway, which is distinct from the force sensing machinery of cell-ECM adhesions.
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Affiliation(s)
- Deborah E Leckband
- School of Chemical Sciences, University of Illinois, Urbana, IL 61822, USA.
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164
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Chang LH, Chen P, Lien MT, Ho YH, Lin CM, Pan YT, Wei SY, Hsu JC. Differential adhesion and actomyosin cable collaborate to drive Echinoid-mediated cell sorting. Development 2011; 138:3803-12. [DOI: 10.1242/dev.062257] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cell sorting involves the segregation of two cell populations into `immiscible' adjacent tissues with smooth borders. Echinoid (Ed), a nectin ortholog, is an adherens junction protein in Drosophila, and cells mutant for ed sort out from the surrounding wild-type cells. However, it remains unknown which factors trigger cell sorting. Here, we dissect the sequence of this process and find that cell sorting occurs when differential expression of Ed triggers the assembly of actomyosin cable. Conversely, Ed-mediated cell sorting can be rescued by recruitment of Ed, via homophilic or heterophilic interactions, to the wild-type cell side of the clonal interface, even when differential Ed expression persists. We found, unexpectedly, that when actomyosin cable was largely absent, differential adhesion was sufficient to cause limited cell segregation but with a jagged tissue border (imperfect sorting). We propose that Ed-mediated cell sorting is driven both by differential Ed adhesion that induces cell segregation with a jagged border and by actomyosin cable assembly at the interface that smoothens this border.
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Affiliation(s)
- Li-Hsun Chang
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Peilong Chen
- Department of Physics, National Central University, Jhongli, Taiwan 32001, Republic of China
| | - Mong-Ting Lien
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Yu-Huei Ho
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Chiao-Ming Lin
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Yi-Ting Pan
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Shu-Yi Wei
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Jui-Chou Hsu
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan 30034, Republic of China
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165
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Becam I, Rafel N, Hong X, Cohen SM, Milán M. Notch-mediated repression of bantam miRNA contributes to boundary formation in the Drosophila wing. Development 2011; 138:3781-9. [DOI: 10.1242/dev.064774] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Subdivision of proliferating tissues into adjacent compartments that do not mix plays a key role in animal development. The Actin cytoskeleton has recently been shown to mediate cell sorting at compartment boundaries, and reduced cell proliferation in boundary cells has been proposed as a way of stabilizing compartment boundaries. Cell interactions mediated by the receptor Notch have been implicated in the specification of compartment boundaries in vertebrates and in Drosophila, but the molecular effectors remain largely unidentified. Here, we present evidence that Notch mediates boundary formation in the Drosophila wing in part through repression of bantam miRNA. bantam induces cell proliferation and we have identified the Actin regulator Enabled as a new target of bantam. Increased levels of Enabled and reduced proliferation rates contribute to the maintenance of the dorsal-ventral affinity boundary. The activity of Notch also defines, through the homeobox-containing gene cut, a distinct population of boundary cells at the dorsal-ventral (DV) interface that helps to segregate boundary from non-boundary cells and contributes to the maintenance of the DV affinity boundary.
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Affiliation(s)
- Isabelle Becam
- Institute for Research in Biomedicine (IRB Barcelona), Parc Científic de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Neus Rafel
- Institute for Research in Biomedicine (IRB Barcelona), Parc Científic de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Xin Hong
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Stephen M. Cohen
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Marco Milán
- Institute for Research in Biomedicine (IRB Barcelona), Parc Científic de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
- ICREA, Parc Científic de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
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166
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Multicomponent analysis of junctional movements regulated by myosin II isoforms at the epithelial zonula adherens. PLoS One 2011; 6:e22458. [PMID: 21799860 PMCID: PMC3142163 DOI: 10.1371/journal.pone.0022458] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 06/27/2011] [Indexed: 11/26/2022] Open
Abstract
The zonula adherens (ZA) of epithelial cells is a site of cell-cell adhesion where cellular forces are exerted and resisted. Increasing evidence indicates that E-cadherin adhesion molecules at the ZA serve to sense force applied on the junctions and coordinate cytoskeletal responses to those forces. Efforts to understand the role that cadherins play in mechanotransduction have been limited by the lack of assays to measure the impact of forces on the ZA. In this study we used 4D imaging of GFP-tagged E-cadherin to analyse the movement of the ZA. Junctions in confluent epithelial monolayers displayed prominent movements oriented orthogonal (perpendicular) to the ZA itself. Two components were identified in these movements: a relatively slow unidirectional (translational) component that could be readily fitted by least-squares regression analysis, upon which were superimposed more rapid oscillatory movements. Myosin IIB was a dominant factor responsible for driving the unilateral translational movements. In contrast, frequency spectrum analysis revealed that depletion of Myosin IIA increased the power of the oscillatory movements. This implies that Myosin IIA may serve to dampen oscillatory movements of the ZA. This extends our recent analysis of Myosin II at the ZA to demonstrate that Myosin IIA and Myosin IIB make distinct contributions to junctional movement at the ZA.
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167
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Fernandez-Gonzalez R, Zallen JA. Oscillatory behaviors and hierarchical assembly of contractile structures in intercalating cells. Phys Biol 2011; 8:045005. [PMID: 21750365 DOI: 10.1088/1478-3975/8/4/045005] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Fluctuations in the size of the apical cell surface have been associated with apical constriction and tissue invagination. However, it is currently not known if apical oscillatory behaviors are a unique property of constricting cells or if they constitute a universal feature of the force balance between cells in multicellular tissues. Here, we set out to determine whether oscillatory cell behaviors occur in parallel with cell intercalation during the morphogenetic process of axis elongation in the Drosophila embryo. We applied multi-color, time-lapse imaging of living embryos and SIESTA, an integrated tool for automated and semi-automated cell segmentation, tracking, and analysis of image sequences. Using SIESTA, we identified cycles of contraction and expansion of the apical surface in intercalating cells and characterized them at the molecular, cellular, and tissue scales. We demonstrate that apical oscillations are anisotropic, and this anisotropy depends on the presence of intact cell-cell junctions and spatial cues provided by the anterior-posterior patterning system. Oscillatory cell behaviors during axis elongation are associated with the hierarchical assembly and disassembly of contractile actomyosin structures at the medial cortex of the cell, with actin localization preceding myosin II and with the localization of both proteins preceding changes in cell shape. We discuss models to explain how the architecture of cytoskeletal networks regulates their contractile behavior and the mechanisms that give rise to oscillatory cell behaviors in intercalating cells.
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Affiliation(s)
- Rodrigo Fernandez-Gonzalez
- Howard Hughes Medical Institute, Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
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168
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Lecuit T, Lenne PF, Munro E. Force generation, transmission, and integration during cell and tissue morphogenesis. Annu Rev Cell Dev Biol 2011; 27:157-84. [PMID: 21740231 DOI: 10.1146/annurev-cellbio-100109-104027] [Citation(s) in RCA: 386] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cell shape changes underlie a large set of biological processes ranging from cell division to cell motility. Stereotyped patterns of cell shape changes also determine tissue remodeling events such as extension or invagination. In vitro and cell culture systems have been essential to understanding the fundamental physical principles of subcellular mechanics. These are now complemented by studies in developing organisms that emphasize how cell and tissue morphogenesis emerge from the interplay between force-generating machines, such as actomyosin networks, and adhesive clusters that transmit tensile forces at the cell cortex and stabilize cell-cell and cell-substrate interfaces. Both force production and transmission are self-organizing phenomena whose adaptive features are essential during tissue morphogenesis. A new era is opening that emphasizes the similarities of and allows comparisons between distant dynamic biological phenomena because they rely on core machineries that control universal features of cytomechanics.
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Affiliation(s)
- Thomas Lecuit
- Developmental Biology Institute of Marseilles-Luminy, Centre National de la Recherche Scientifique, Université de la Méditerranée, 13288 Marseille Cedex 9, France.
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169
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Monier B, Pélissier-Monier A, Sanson B. Establishment and maintenance of compartmental boundaries: role of contractile actomyosin barriers. Cell Mol Life Sci 2011; 68:1897-910. [PMID: 21437644 PMCID: PMC11114499 DOI: 10.1007/s00018-011-0668-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 02/12/2011] [Accepted: 03/08/2011] [Indexed: 12/29/2022]
Abstract
During animal development, tissues and organs are partitioned into compartments that do not intermix. This organizing principle is essential for correct tissue morphogenesis. Given that cell sorting defects during compartmentalization in humans are thought to cause malignant invasion and congenital defects such as cranio-fronto-nasal syndrome, identifying the molecular and cellular mechanisms that keep cells apart at boundaries between compartments is important. In both vertebrates and invertebrates, transcription factors and short-range signalling pathways, such as EPH/Ephrin, Hedgehog, or Notch signalling, govern compartmental cell sorting. However, the mechanisms that mediate cell sorting downstream of these factors have remained elusive for decades. Here, we review recent data gathered in Drosophila that suggest that the generation of cortical tensile forces at compartmental boundaries by the actomyosin cytoskeleton could be a general mechanism that inhibits cell mixing between compartments.
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Affiliation(s)
- Bruno Monier
- Department of Physiology, Development and Neuroscience, Anatomy Building, Downing Street, Cambridge, CB2 3DY UK
- Present Address: Institut de Biologie du Développement de Marseille-Luminy, UMR6216, Campus de Luminy, Case 907, 13288 Marseille cedex 9, France
| | - Anne Pélissier-Monier
- Department of Physiology, Development and Neuroscience, Anatomy Building, Downing Street, Cambridge, CB2 3DY UK
- Wellcome Trust, Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN UK
- Present Address: Institut de Biologie du Développement de Marseille-Luminy, UMR6216, Campus de Luminy, Case 907, 13288 Marseille cedex 9, France
| | - Bénédicte Sanson
- Department of Physiology, Development and Neuroscience, Anatomy Building, Downing Street, Cambridge, CB2 3DY UK
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170
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Baum B, Georgiou M. Dynamics of adherens junctions in epithelial establishment, maintenance, and remodeling. ACTA ACUST UNITED AC 2011; 192:907-17. [PMID: 21422226 PMCID: PMC3063136 DOI: 10.1083/jcb.201009141] [Citation(s) in RCA: 370] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The epithelial cadherin (E-cadherin)–catenin complex binds to cytoskeletal components and regulatory and signaling molecules to form a mature adherens junction (AJ). This dynamic structure physically connects neighboring epithelial cells, couples intercellular adhesive contacts to the cytoskeleton, and helps define each cell’s apical–basal axis. Together these activities coordinate the form, polarity, and function of all cells in an epithelium. Several molecules regulate AJ formation and integrity, including Rho family GTPases and Par polarity proteins. However, only recently, with the development of live-cell imaging, has the extent to which E-cadherin is actively turned over at junctions begun to be appreciated. This turnover contributes to junction formation and to the maintenance of epithelial integrity during tissue homeostasis and remodeling.
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Affiliation(s)
- Buzz Baum
- University College London, London WC1E 6BT, England, UK
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171
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Schilling S, Willecke M, Aegerter-Wilmsen T, Cirpka OA, Basler K, von Mering C. Cell-sorting at the A/P boundary in the Drosophila wing primordium: a computational model to consolidate observed non-local effects of Hh signaling. PLoS Comput Biol 2011; 7:e1002025. [PMID: 21490725 PMCID: PMC3072364 DOI: 10.1371/journal.pcbi.1002025] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 02/16/2011] [Indexed: 12/31/2022] Open
Abstract
Non-intermingling, adjacent populations of cells define compartment boundaries;
such boundaries are often essential for the positioning and the maintenance of
tissue-organizers during growth. In the developing wing primordium of
Drosophila melanogaster, signaling by the secreted protein
Hedgehog (Hh) is required for compartment boundary maintenance. However, the
precise mechanism of Hh input remains poorly understood. Here, we combine
experimental observations of perturbed Hh signaling with computer simulations of
cellular behavior, and connect physical properties of cells to their Hh
signaling status. We find that experimental disruption of Hh signaling has
observable effects on cell sorting surprisingly far from the compartment
boundary, which is in contrast to a previous model that confines Hh influence to
the compartment boundary itself. We have recapitulated our experimental
observations by simulations of Hh diffusion and transduction coupled to
mechanical tension along cell-to-cell contact surfaces. Intriguingly, the best
results were obtained under the assumption that Hh signaling cannot alter the
overall tension force of the cell, but will merely re-distribute it locally
inside the cell, relative to the signaling status of neighboring cells. Our
results suggest a scenario in which homotypic interactions of a putative Hh
target molecule at the cell surface are converted into a mechanical force. Such
a scenario could explain why the mechanical output of Hh signaling appears to be
confined to the compartment boundary, despite the longer range of the Hh
molecule itself. Our study is the first to couple a cellular vertex model
describing mechanical properties of cells in a growing tissue, to an explicit
model of an entire signaling pathway, including a freely diffusible component.
We discuss potential applications and challenges of such an approach. In developing animal tissues, cells can often re-arrange locally and mix
relatively freely. However, in some stereotypic and crucially important
instances during body development, cells will strictly not intermingle, and
instead form sharp boundaries along which they will sort out from each other.
This mechanism helps organisms to establish signaling centers and to maintain
distinct cellular identities. Often, cells at such boundaries will remain in
close physical contact and are morphologically alike. Thus, the boundary itself
can be difficult to observe unless the expression status of specific marker
genes is monitored experimentally. How are these ‘compartment
boundaries’ established? Here we devise a computational model that aims to
describe one such boundary in a well-studied animal tissue: the developing wing
primordium of Drosophila melanogaster. We model the production,
diffusion and local sensing of an essential signaling molecule, the
Hedgehog protein. We reveal one possible mechanism by which
Hedgehog sensing can influence the mechanical properties of cells, and compare
the simulated outcome to observations in experimentally perturbed, actual wing
discs. Our relatively simple model suffices to establish a straight and stable
compartment boundary.
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Affiliation(s)
- Sabine Schilling
- Institute of Molecular Life Sciences, University of Zurich, Zurich,
Switzerland
- Swiss Institute of Bioinformatics, University of Zurich, Zurich,
Switzerland
| | - Maria Willecke
- Institute of Molecular Life Sciences, University of Zurich, Zurich,
Switzerland
| | | | - Olaf A. Cirpka
- Center for Applied Geoscience, University of Tuebingen, Tuebingen,
Germany
| | - Konrad Basler
- Institute of Molecular Life Sciences, University of Zurich, Zurich,
Switzerland
| | - Christian von Mering
- Institute of Molecular Life Sciences, University of Zurich, Zurich,
Switzerland
- Swiss Institute of Bioinformatics, University of Zurich, Zurich,
Switzerland
- * E-mail:
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172
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Abstract
Cortical forces drive a variety of cell shape changes and cell movements during tissue morphogenesis. While the molecular components underlying these forces have been largely identified, how they assemble and spatially and temporally organize at cell surfaces to promote cell shape changes in developing tissues are open questions. We present here different key aspects of cortical forces: their physical nature, some rules governing their emergence, and how their deployment at cell surfaces drives important morphogenetic movements in epithelia. We review a wide range of literature combining genetic/molecular, biophysical and modeling approaches, which explore essential features of cortical force generation and transmission in tissues.
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Affiliation(s)
- Matteo Rauzi
- IBDML, UMR6216 CNRS-Université de Méditerraneé, Campus de Luminy, Case 907, 13288 Marseille Cedex 09, France
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173
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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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174
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Abstract
During the development of multicellular organisms, cell fate specification is followed by the sorting of different cell types into distinct domains from where the different tissues and organs are formed. Cell sorting involves both the segregation of a mixed population of cells with different fates and properties into distinct domains, and the active maintenance of their segregated state. Because of its biological importance and apparent resemblance to fluid segregation in physics, cell sorting was extensively studied by both biologists and physicists over the last decades. Different theories were developed that try to explain cell sorting on the basis of the physical properties of the constituent cells. However, only recently the molecular and cellular mechanisms that control the physical properties driving cell sorting, have begun to be unraveled. In this review, we will provide an overview of different cell-sorting processes in development and discuss how these processes can be explained by the different sorting theories, and how these theories in turn can be connected to the molecular and cellular mechanisms driving these processes.
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Affiliation(s)
- S F Gabby Krens
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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175
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176
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Kasza KE, Zallen JA. Dynamics and regulation of contractile actin-myosin networks in morphogenesis. Curr Opin Cell Biol 2010; 23:30-8. [PMID: 21130639 DOI: 10.1016/j.ceb.2010.10.014] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 10/25/2010] [Accepted: 10/30/2010] [Indexed: 11/18/2022]
Abstract
Contractile actin-myosin networks generate forces that drive cell shape changes and tissue remodeling during development. These forces can also actively regulate cell signaling and behavior. Novel features of actin-myosin network dynamics, such as pulsed contractile behaviors and the regulation of myosin localization by tension, have been uncovered in recent studies of Drosophila. In vitro studies of single molecules and reconstituted protein networks reveal intrinsic properties of motor proteins and actin-myosin networks, while in vivo studies have provided insight into the regulation of their dynamics and organization. Analysis of the complex behaviors of actin-myosin networks will be crucial for understanding force generation in actively remodeling cells and the coordination of cell shape and movement at the tissue level.
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Affiliation(s)
- Karen E Kasza
- Howard Hughes Medical Institute, Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
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177
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Rauzi M, Lenne PF, Lecuit T. Planar polarized actomyosin contractile flows control epithelial junction remodelling. Nature 2010; 468:1110-4. [PMID: 21068726 DOI: 10.1038/nature09566] [Citation(s) in RCA: 455] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 10/08/2010] [Indexed: 01/01/2023]
Abstract
Force generation by Myosin-II motors on actin filaments drives cell and tissue morphogenesis. In epithelia, contractile forces are resisted at apical junctions by adhesive forces dependent on E-cadherin, which also transmits tension. During Drosophila embryonic germband extension, tissue elongation is driven by cell intercalation, which requires an irreversible and planar polarized remodelling of epithelial cell junctions. We investigate how cell deformations emerge from the interplay between force generation and cortical force transmission during this remodelling in Drosophila melanogaster. The shrinkage of dorsal-ventral-oriented ('vertical') junctions during this process is known to require planar polarized junctional contractility by Myosin II (refs 4, 5, 7, 12). Here we show that this shrinkage is not produced by junctional Myosin II itself, but by the polarized flow of medial actomyosin pulses towards 'vertical' junctions. This anisotropic flow is oriented by the planar polarized distribution of E-cadherin complexes, in that medial Myosin II flows towards 'vertical' junctions, which have relatively less E-cadherin than transverse junctions. Our evidence suggests that the medial flow pattern reflects equilibrium properties of force transmission and coupling to E-cadherin by α-Catenin. Thus, epithelial morphogenesis is not properly reflected by Myosin II steady state distribution but by polarized contractile actomyosin flows that emerge from interactions between E-cadherin and actomyosin networks.
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Affiliation(s)
- Matteo Rauzi
- IBDML, UMR6216 CNRS-Université de la Méditerranée, Campus de Luminy, case 907, 13288 Marseille Cedex 09, France
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178
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Simões SDM, Blankenship JT, Weitz O, Farrell DL, Tamada M, Fernandez-Gonzalez R, Zallen JA. Rho-kinase directs Bazooka/Par-3 planar polarity during Drosophila axis elongation. Dev Cell 2010; 19:377-88. [PMID: 20833361 DOI: 10.1016/j.devcel.2010.08.011] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Revised: 07/07/2010] [Accepted: 08/17/2010] [Indexed: 12/01/2022]
Abstract
Cell rearrangements shape the Drosophila embryo via spatially regulated changes in cell shape and adhesion. We show that Bazooka/Par-3 (Baz) is required for the planar polarized distribution of myosin II and adherens junction proteins and polarized intercalary behavior is disrupted in baz mutants. The myosin II activator Rho-kinase is asymmetrically enriched at the anterior and posterior borders of intercalating cells in a pattern complementary to Baz. Loss of Rho-kinase results in expansion of the Baz domain, and activated Rho-kinase is sufficient to exclude Baz from the cortex. The planar polarized distribution of Baz requires its C-terminal domain. Rho-kinase can phosphorylate this domain and inhibit its interaction with phosphoinositide membrane lipids, suggesting a mechanism by which Rho-kinase could regulate Baz association with the cell cortex. These results demonstrate that Rho-kinase plays an instructive role in planar polarity by targeting Baz/Par-3 and myosin II to complementary cortical domains.
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Affiliation(s)
- Sérgio de Matos Simões
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10065, USA
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179
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Ou G, Stuurman N, D'Ambrosio M, Vale RD. Polarized myosin produces unequal-size daughters during asymmetric cell division. Science 2010; 330:677-80. [PMID: 20929735 DOI: 10.1126/science.1196112] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Asymmetric positioning of the mitotic spindle before cytokinesis can produce different-sized daughter cells that have distinct fates. Here, we found an asymmetric division in the Caenorhabditis elegans Q neuroblast lineage that began with a centered spindle but generated different-sized daughters, the smaller (anterior) of which underwent apoptosis. During this division, more myosin II accumulated anteriorly, suggesting that asymmetric contractile forces might produce different-sized daughters. Indeed, partial inactivation of anterior myosin by chromophore-assisted laser inactivation created a more symmetric division and allowed the survival and differentiation of the anterior daughter. Thus, the balance of myosin activity on the two sides of a dividing cell can govern the size and fate of the daughters.
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Affiliation(s)
- Guangshuo Ou
- The Howard Hughes Medical Institute and the Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
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180
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Zhang H, Gally C, Labouesse M. Tissue morphogenesis: how multiple cells cooperate to generate a tissue. Curr Opin Cell Biol 2010; 22:575-82. [PMID: 20822890 DOI: 10.1016/j.ceb.2010.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 08/09/2010] [Accepted: 08/09/2010] [Indexed: 10/19/2022]
Abstract
Genetic analysis in model organisms has recently achieved a detailed molecular description of many key cellular processes controlling embryonic morphogenesis. To understand higher order tissue morphogenesis, we now need to define how these processes become integrated across different cell groups and cell layers. Here, we review progress in this fast moving area, which was to a large degree made possible by novel imaging methods and the increasingly frequent use of modeling. Discussing examples from Caenorhabditis elegans and Drosophila embryos, two powerful and simple models, we highlight novel principles relying in part on mechanical tension, and outline the role of junctions as signal integrators.
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Affiliation(s)
- Huimin Zhang
- IGBMC, CNRS/INSERM/Université de Strasbourg, 1 rue Laurent Fries, BP. 10142, 67404 Illkirch CEDEX, France
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181
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Umetsu D, Dahmann C. Compartment boundaries: sorting cells with tension. Fly (Austin) 2010; 4:241-5. [PMID: 20495386 PMCID: PMC3322502 DOI: 10.4161/fly.4.3.12173] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 04/26/2010] [Indexed: 11/19/2022] Open
Abstract
The subdivision of proliferating tissues into groups of non-intermingling sets of cells, termed compartments, is a common process of animal development. Signaling between adjacent compartments induces the local expression of morphogens that pattern the surrounding tissue. Sharp and straight boundaries between compartments stabilize the source of such morphogens during tissue growth and, thus, are of crucial importance for pattern formation. Signaling pathways required to maintain compartment boundaries have been identified, yet the physical mechanisms that maintain compartment boundaries remained elusive. Recent data now show that a local increase in actomyosin-based mechanical tension on cell bonds is vital for maintaining compartment boundaries in Drosophila.
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Affiliation(s)
- Daiki Umetsu
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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182
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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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183
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Kim JH, Dooling LJ, Asthagiri AR. Intercellular mechanotransduction during multicellular morphodynamics. J R Soc Interface 2010; 7 Suppl 3:S341-50. [PMID: 20356878 DOI: 10.1098/rsif.2010.0066.focus] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Multicellular structures are held together by cell adhesions. Forces that act upon these adhesions play an integral role in dynamically re-shaping multicellular structures during development and disease. Here, we describe different modes by which mechanical forces are transduced in a multicellular context: (i) indirect mechanosensing through compliant substratum, (ii) cytoskeletal 'tug-of-war' between cell-matrix and cell-cell adhesions, (iii) cortical contractility contributing to line tension, (iv) stresses associated with cell proliferation, and (v) forces mediating collective migration. These modes of mechanotransduction are recurring motifs as they play a key role in shaping multicellular structures in a wide range of biological contexts. Tissue morphodynamics may ultimately be understood as different spatio-temporal combinations of a select few multicellular transformations, which in turn are driven by these mechanotransduction motifs that operate at the bicellular to multicellular length scale.
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Affiliation(s)
- Jin-Hong Kim
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
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184
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Abstract
During development, proliferating cells are organized into compartments with boundaries across which cells fail to intermix. Compartment boundaries are often attributed to differential cell-cell adhesion between separate compartments. However, tension generated by actomyosin cables at boundaries can also function as a barrier that prevents cell mixing.
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185
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Development: Tension at the borders. Nat Rev Mol Cell Biol 2010; 11:4. [PMID: 20050306 DOI: 10.1038/nrm2827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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