1
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Pinot M, Le Borgne R. Spatio-Temporal Regulation of Notch Activation in Asymmetrically Dividing Sensory Organ Precursor Cells in Drosophila melanogaster Epithelium. Cells 2024; 13:1133. [PMID: 38994985 PMCID: PMC11240559 DOI: 10.3390/cells13131133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/13/2024] Open
Abstract
The Notch communication pathway, discovered in Drosophila over 100 years ago, regulates a wide range of intra-lineage decisions in metazoans. The division of the Drosophila mechanosensory organ precursor is the archetype of asymmetric cell division in which differential Notch activation takes place at cytokinesis. Here, we review the molecular mechanisms by which epithelial cell polarity, cell cycle and intracellular trafficking participate in controlling the directionality, subcellular localization and temporality of mechanosensitive Notch receptor activation in cytokinesis.
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Affiliation(s)
| | - Roland Le Borgne
- Univ Rennes, Centre National de la Recherche Scientifique UMR 6290, IGDR (Institut de Génétique et Développement de Rennes), F-35000 Rennes, France
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2
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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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3
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Popkova A, Andrenšek U, Pagnotta S, Ziherl P, Krajnc M, Rauzi M. A mechanical wave travels along a genetic guide to drive the formation of an epithelial furrow during Drosophila gastrulation. Dev Cell 2024; 59:400-414.e5. [PMID: 38228140 DOI: 10.1016/j.devcel.2023.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/08/2023] [Accepted: 12/21/2023] [Indexed: 01/18/2024]
Abstract
Epithelial furrowing is a fundamental morphogenetic process during gastrulation, neurulation, and body shaping. A furrow often results from a fold that propagates along a line. How fold formation and propagation are controlled and driven is poorly understood. To shed light on this, we study the formation of the cephalic furrow, a fold that runs along the embryo dorsal-ventral axis during Drosophila gastrulation and the developmental role of which is still unknown. We provide evidence of its function and show that epithelial furrowing is initiated by a group of cells. This cellular cluster works as a pacemaker, triggering a bidirectional morphogenetic wave powered by actomyosin contractions and sustained by de novo medial apex-to-apex cell adhesion. The pacemaker's Cartesian position is under the crossed control of the anterior-posterior and dorsal-ventral gene patterning systems. Thus, furrow formation is driven by a mechanical trigger wave that travels under the control of a multidimensional genetic guide.
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Affiliation(s)
- Anna Popkova
- Université Côte d'Azur, CNRS, Inserm, iBV, Nice, France.
| | - Urška Andrenšek
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia; Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Sophie Pagnotta
- Université Côte d'Azur, Centre Commun de Microscopie Appliquée, Nice, France
| | - Primož Ziherl
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia; Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Matej Krajnc
- Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Matteo Rauzi
- Université Côte d'Azur, CNRS, Inserm, iBV, Nice, France.
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4
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Clarke DN, Martin AC. EGFR-dependent actomyosin patterning coordinates morphogenetic movements between tissues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.22.573057. [PMID: 38187543 PMCID: PMC10769333 DOI: 10.1101/2023.12.22.573057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The movements that give rise to the body's structure are powered by cell shape changes and rearrangements that are coordinated at supracellular scales. How such cellular coordination arises and integrates different morphogenetic programs is unclear. Using quantitative imaging, we found a complex pattern of adherens junction (AJ) levels in the ectoderm prior to gastrulation onset in Drosophila. AJ intensity exhibited a double-sided gradient, with peaks at the dorsal midline and ventral neuroectoderm. We show that this dorsal-ventral AJ pattern is regulated by epidermal growth factor (EGF) signaling and that this signal is required for ectoderm cell movement during mesoderm invagination and axis extension. We identify AJ levels and junctional actomyosin as downstream effectors of EGFR signaling. Overall, our study demonstrates a mechanism of coordination between tissue folding and convergent extension that facilitates embryo-wide gastrulation movements.
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Affiliation(s)
| | - Adam C Martin
- Dept. of Biology, Massachusetts Institute of Technology
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5
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Burda I, Martin AC, Roeder AHK, Collins MA. The dynamics and biophysics of shape formation: Common themes in plant and animal morphogenesis. Dev Cell 2023; 58:2850-2866. [PMID: 38113851 PMCID: PMC10752614 DOI: 10.1016/j.devcel.2023.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 09/19/2023] [Accepted: 11/10/2023] [Indexed: 12/21/2023]
Abstract
The emergence of tissue form in multicellular organisms results from the complex interplay between genetics and physics. In both plants and animals, cells must act in concert to pattern their behaviors. Our understanding of the factors sculpting multicellular form has increased dramatically in the past few decades. From this work, common themes have emerged that connect plant and animal morphogenesis-an exciting connection that solidifies our understanding of the developmental basis of multicellular life. In this review, we will discuss the themes and the underlying principles that connect plant and animal morphogenesis, including the coordination of gene expression, signaling, growth, contraction, and mechanical and geometric feedback.
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Affiliation(s)
- Isabella Burda
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA; Genetic Genomics and Development Program, Cornell University, Ithaca, NY 14853, USA
| | - Adam C Martin
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Adrienne H K Roeder
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA; Genetic Genomics and Development Program, Cornell University, Ithaca, NY 14853, USA; School of Integrative Plant Sciences, Section of Plant Biology, Cornell University, Ithaca, NY 14850, USA.
| | - Mary Ann Collins
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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6
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Cheikh MI, Tchoufag J, Osterfield M, Dean K, Bhaduri S, Zhang C, Mandadapu KK, Doubrovinski K. A comprehensive model of Drosophila epithelium reveals the role of embryo geometry and cell topology in mechanical responses. eLife 2023; 12:e85569. [PMID: 37782009 PMCID: PMC10584372 DOI: 10.7554/elife.85569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 09/29/2023] [Indexed: 10/03/2023] Open
Abstract
In order to understand morphogenesis, it is necessary to know the material properties or forces shaping the living tissue. In spite of this need, very few in vivo measurements are currently available. Here, using the early Drosophila embryo as a model, we describe a novel cantilever-based technique which allows for the simultaneous quantification of applied force and tissue displacement in a living embryo. By analyzing data from a series of experiments in which embryonic epithelium is subjected to developmentally relevant perturbations, we conclude that the response to applied force is adiabatic and is dominated by elastic forces and geometric constraints, or system size effects. Crucially, computational modeling of the experimental data indicated that the apical surface of the epithelium must be softer than the basal surface, a result which we confirmed experimentally. Further, we used the combination of experimental data and comprehensive computational model to estimate the elastic modulus of the apical surface and set a lower bound on the elastic modulus of the basal surface. More generally, our investigations revealed important general features that we believe should be more widely addressed when quantitatively modeling tissue mechanics in any system. Specifically, different compartments of the same cell can have very different mechanical properties; when they do, they can contribute differently to different mechanical stimuli and cannot be merely averaged together. Additionally, tissue geometry can play a substantial role in mechanical response, and cannot be neglected.
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Affiliation(s)
- Mohamad Ibrahim Cheikh
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Joel Tchoufag
- Department of Chemical and Biomolecular Engineering, University of California, BerkeleyBerkeleyUnited States
- Chemical Sciences Division, Lawrence Berkeley National LaboratoryBerkeleyUnited States
| | - Miriam Osterfield
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Kevin Dean
- Department of Bioinformatics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Swayamdipta Bhaduri
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
| | - Chuzhong Zhang
- Department of Material Science and Engineering, University of Texas at ArlingtonArlingtonUnited States
| | - Kranthi Kiran Mandadapu
- Department of Chemical and Biomolecular Engineering, University of California, BerkeleyBerkeleyUnited States
- Chemical Sciences Division, Lawrence Berkeley National LaboratoryBerkeleyUnited States
| | - Konstantin Doubrovinski
- Department of Biophysics, University of Texas Southwestern Medical CenterDallasUnited States
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7
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Simões S, Lerchbaumer G, Pellikka M, Giannatou P, Lam T, Kim D, Yu J, ter Stal D, Al Kakouni K, Fernandez-Gonzalez R, Tepass U. Crumbs complex-directed apical membrane dynamics in epithelial cell ingression. J Cell Biol 2022; 221:213229. [PMID: 35588693 PMCID: PMC9123285 DOI: 10.1083/jcb.202108076] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 02/24/2022] [Accepted: 04/29/2022] [Indexed: 01/07/2023] Open
Abstract
Epithelial cells often leave their tissue context and ingress to form new cell types or acquire migratory ability to move to distant sites during development and tumor progression. Cells lose their apical membrane and epithelial adherens junctions during ingression. However, how factors that organize apical-basal polarity contribute to ingression is unknown. Here, we show that the dynamic regulation of the apical Crumbs polarity complex is crucial for normal neural stem cell ingression. Crumbs endocytosis and recycling allow ingression to occur in a normal timeframe. During early ingression, Crumbs and its complex partner the RhoGEF Cysts support myosin and apical constriction to ensure robust ingression dynamics. During late ingression, the E3-ubiquitin ligase Neuralized facilitates the disassembly of the Crumbs complex and the rapid endocytic removal of the apical cell domain. Our findings reveal a mechanism integrating cell fate, apical polarity, endocytosis, vesicle trafficking, and actomyosin contractility to promote cell ingression, a fundamental morphogenetic process observed in animal development and cancer.
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Affiliation(s)
- Sérgio Simões
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Gerald Lerchbaumer
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Milena Pellikka
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Paraskevi Giannatou
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Thomas Lam
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Dohyun Kim
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Jessica Yu
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada,Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - David ter Stal
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Kenana Al Kakouni
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada,Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada,Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada,Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ulrich Tepass
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada,Correspondence to Ulrich Tepass:
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8
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Guo H, Huang S, He B. Evidence for a Role of the Lateral Ectoderm in Drosophila Mesoderm Invagination. Front Cell Dev Biol 2022; 10:867438. [PMID: 35547820 PMCID: PMC9081377 DOI: 10.3389/fcell.2022.867438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/01/2022] [Indexed: 01/09/2023] Open
Abstract
The folding of two-dimensional epithelial sheets into specific three-dimensional structures is a fundamental tissue construction mechanism in animal development. A common mechanism that mediates epithelial folding is apical constriction, the active shrinking of cell apices driven by actomyosin contractions. It remains unclear whether cells outside of the constriction domain also contribute to folding. During Drosophila mesoderm invagination, ventrally localized mesoderm epithelium undergoes apical constriction and subsequently folds into a furrow. While the critical role of apical constriction in ventral furrow formation has been well demonstrated, it remains unclear whether, and if so, how the laterally localized ectodermal tissue adjacent to the mesoderm contributes to furrow invagination. In this study, we combine experimental and computational approaches to test the potential function of the ectoderm in mesoderm invagination. Through laser-mediated, targeted disruption of cell formation prior to gastrulation, we found that the presence of intact lateral ectoderm is important for the effective transition between apical constriction and furrow invagination in the mesoderm. In addition, using a laser-ablation approach widely used for probing tissue tension, we found that the lateral ectodermal tissues exhibit signatures of tissue compression when ablation was performed shortly before the onset of mesoderm invagination. These observations led to the hypothesis that in-plane compression from the surrounding ectoderm facilitates mesoderm invagination by triggering buckling of the mesoderm epithelium. In support of this notion, we show that the dynamics of tissue flow during mesoderm invagination displays characteristic of elastic buckling, and this tissue dynamics can be recapitulated by combining local apical constriction and global compression in a simulated elastic monolayer. We propose that Drosophila mesoderm invagination is achieved through epithelial buckling jointly mediated by apical constriction in the mesoderm and compression from the neighboring ectoderm.
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Affiliation(s)
| | | | - Bing He
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
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9
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Fuentes MA, He B. The cell polarity determinant Dlg1 facilitates epithelial invagination by promoting tissue-scale mechanical coordination. Development 2022; 149:274757. [PMID: 35302584 PMCID: PMC8977094 DOI: 10.1242/dev.200468] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 01/27/2022] [Indexed: 12/23/2022]
Abstract
Epithelial folding mediated by apical constriction serves as a fundamental mechanism to convert flat epithelial sheets into multilayered structures. It remains unknown whether additional mechanical inputs are required for apical constriction-mediated folding. Using Drosophila mesoderm invagination as a model, we identified an important role for the non-constricting, lateral mesodermal cells adjacent to the constriction domain ('flanking cells') in facilitating epithelial folding. We found that depletion of the basolateral determinant Dlg1 disrupts the transition between apical constriction and invagination without affecting the rate of apical constriction. Strikingly, the observed delay in invagination is associated with ineffective apical myosin contractions in the flanking cells that lead to overstretching of their apical domain. The defects in the flanking cells impede ventral-directed movement of the lateral ectoderm, suggesting reduced mechanical coupling between tissues. Specifically disrupting the flanking cells in wild-type embryos by laser ablation or optogenetic depletion of cortical actin is sufficient to delay the apical constriction-to-invagination transition. Our findings indicate that effective mesoderm invagination requires intact flanking cells and suggest a role for tissue-scale mechanical coupling during epithelial folding.
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Affiliation(s)
- Melisa A Fuentes
- Dartmouth College, Department of Biological Sciences, Hanover, NH 03755, USA
| | - Bing He
- Dartmouth College, Department of Biological Sciences, Hanover, NH 03755, USA
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10
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Guo H, Swan M, He B. Optogenetic inhibition of actomyosin reveals mechanical bistability of the mesoderm epithelium during Drosophila mesoderm invagination. eLife 2022; 11:e69082. [PMID: 35195065 PMCID: PMC8896829 DOI: 10.7554/elife.69082] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 02/22/2022] [Indexed: 12/05/2022] Open
Abstract
Apical constriction driven by actin and non-muscle myosin II (actomyosin) provides a well-conserved mechanism to mediate epithelial folding. It remains unclear how contractile forces near the apical surface of a cell sheet drive out-of-the-plane bending of the sheet and whether myosin contractility is required throughout folding. By optogenetic-mediated acute inhibition of actomyosin, we find that during Drosophila mesoderm invagination, actomyosin contractility is critical to prevent tissue relaxation during the early, 'priming' stage of folding but is dispensable for the actual folding step after the tissue passes through a stereotyped transitional configuration. This binary response suggests that Drosophila mesoderm is mechanically bistable during gastrulation. Computer modeling analysis demonstrates that the binary tissue response to actomyosin inhibition can be recapitulated in the simulated epithelium that undergoes buckling-like deformation jointly mediated by apical constriction in the mesoderm and in-plane compression generated by apicobasal shrinkage of the surrounding ectoderm. Interestingly, comparison between wild-type and snail mutants that fail to specify the mesoderm demonstrates that the lateral ectoderm undergoes apicobasal shrinkage during gastrulation independently of mesoderm invagination. We propose that Drosophila mesoderm invagination is achieved through an interplay between local apical constriction and mechanical bistability of the epithelium that facilitates epithelial buckling.
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Affiliation(s)
- Hanqing Guo
- Department of Biological Sciences, Dartmouth CollegeHanoverUnited States
| | - Michael Swan
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Bing He
- Department of Biological Sciences, Dartmouth CollegeHanoverUnited States
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11
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Yamashita S, Guirao B, Graner F. From heterogeneous morphogenetic fields to homogeneous regions as a step towards understanding complex tissue dynamics. Development 2021; 148:273621. [PMID: 34861038 DOI: 10.1242/dev.199034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 10/25/2021] [Indexed: 11/20/2022]
Abstract
Within developing tissues, cell proliferation, cell motility and other cell behaviors vary spatially, and this variability gives a complexity to the morphogenesis. Recently, novel formalisms have been developed to quantify tissue deformation and underlying cellular processes. A major challenge for the study of morphogenesis now is to objectively define tissue sub-regions exhibiting different dynamics. Here, we propose a method to automatically divide a tissue into regions where the local deformation rate is homogeneous. This was achieved by several steps including image segmentation, clustering and region boundary smoothing. We illustrate the use of the pipeline using a large dataset obtained during the metamorphosis of the Drosophila pupal notum. We also adapt it to determine regions in which the time evolution of the local deformation rate is homogeneous. Finally, we generalize its use to find homogeneous regions for cellular processes such as cell division, cell rearrangement, or cell size and shape changes. We also illustrate it on wing blade morphogenesis. This pipeline will contribute substantially to the analysis of complex tissue shaping, and the biochemical and biomechanical regulations driving tissue morphogenesis.
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Affiliation(s)
- Satoshi Yamashita
- Laboratoire Matière et Systèmes Complexes (CNRS UMR7057), Université de Paris-Diderot, F-75205 Paris Cedex 13, France
| | - Boris Guirao
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, F-75248 Paris Cedex 05, France
| | - François Graner
- Laboratoire Matière et Systèmes Complexes (CNRS UMR7057), Université de Paris-Diderot, F-75205 Paris Cedex 13, France
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12
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Bhide S, Gombalova D, Mönke G, Stegmaier J, Zinchenko V, Kreshuk A, Belmonte JM, Leptin M. Mechanical competition alters the cellular interpretation of an endogenous genetic program. J Cell Biol 2021; 220:212605. [PMID: 34449835 PMCID: PMC8406609 DOI: 10.1083/jcb.202104107] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/26/2021] [Accepted: 07/30/2021] [Indexed: 12/16/2022] Open
Abstract
The intrinsic genetic program of a cell is not sufficient to explain all of the cell's activities. External mechanical stimuli are increasingly recognized as determinants of cell behavior. In the epithelial folding event that constitutes the beginning of gastrulation in Drosophila, the genetic program of the future mesoderm leads to the establishment of a contractile actomyosin network that triggers apical constriction of cells and thereby tissue folding. However, some cells do not constrict but instead stretch, even though they share the same genetic program as their constricting neighbors. We show here that tissue-wide interactions force these cells to expand even when an otherwise sufficient amount of apical, active actomyosin is present. Models based on contractile forces and linear stress-strain responses do not reproduce experimental observations, but simulations in which cells behave as ductile materials with nonlinear mechanical properties do. Our models show that this behavior is a general emergent property of actomyosin networks in a supracellular context, in accordance with our experimental observations of actin reorganization within stretching cells.
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Affiliation(s)
- Sourabh Bhide
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Denisa Gombalova
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Gregor Mönke
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Johannes Stegmaier
- Institute of Imaging and Computer Vision, Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen, Germany
| | - Valentyna Zinchenko
- Collaboration for Joint PhD Degree between European Molecular Biology Laboratory and Faculty of Biosciences, Heidelberg University, Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Anna Kreshuk
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Julio M Belmonte
- Department of Physics, North Carolina State University, Raleigh, NC.,Quantitative and Computational Developmental Biology Cluster, North Carolina State University, Raleigh, NC
| | - Maria Leptin
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,European Molecular Biology Organization, Heidelberg, Germany
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13
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Rich A, Glotzer M. Small GTPases modulate intrinsic and extrinsic forces that control epithelial folding in Drosophila embryos. Small GTPases 2021; 12:416-428. [PMID: 33985411 DOI: 10.1080/21541248.2021.1926879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Epithelial folding is a common means to execute morphogenetic movements. The gastrulating Drosophila embryo offers many examples of epithelial folding events, including the ventral, cephalic, and dorsal furrows. Each of these folding events is associated with changes in intracellular contractility and/or cytoskeleton structures that autonomously promote epithelial folding. Here, we review accumulating evidence that suggests the progression and final form of ventral, cephalic, and dorsal furrows are also influenced by the behaviour of cells neighbouring these folds. We further discuss the prevalence and importance of junctional rearrangements during epithelial folding events, suggesting adherens junction components are prime candidates to modulate the transmission of the intercellular forces that influence folding events. Finally, we discuss how recently developed methods that enable precise spatial and/or temporal control of protein activity allow direct testing of molecular models of morphogenesis in vivo.
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Affiliation(s)
- Ashley Rich
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA.,Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
| | - Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
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14
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Denk-Lobnig M, Totz JF, Heer NC, Dunkel J, Martin AC. Combinatorial patterns of graded RhoA activation and uniform F-actin depletion promote tissue curvature. Development 2021; 148:dev199232. [PMID: 34124762 PMCID: PMC8254875 DOI: 10.1242/dev.199232] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/04/2021] [Indexed: 01/03/2023]
Abstract
During development, gene expression regulates cell mechanics and shape to sculpt tissues. Epithelial folding proceeds through distinct cell shape changes that occur simultaneously in different regions of a tissue. Here, using quantitative imaging in Drosophila melanogaster, we investigate how patterned cell shape changes promote tissue bending during early embryogenesis. We find that the transcription factors Twist and Snail combinatorially regulate a multicellular pattern of lateral F-actin density that differs from the previously described Myosin-2 gradient. This F-actin pattern correlates with whether cells apically constrict, stretch or maintain their shape. We show that the Myosin-2 gradient and F-actin depletion do not depend on force transmission, suggesting that transcriptional activity is required to create these patterns. The Myosin-2 gradient width results from a gradient in RhoA activation that is refined through the balance between RhoGEF2 and the RhoGAP C-GAP. Our experimental results and simulations of a 3D elastic shell model show that tuning gradient width regulates tissue curvature.
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Affiliation(s)
- Marlis Denk-Lobnig
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
| | - Jan F. Totz
- Mathematics Department, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Natalie C. Heer
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
| | - Jörn Dunkel
- Mathematics Department, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
| | - Adam C. Martin
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
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15
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Abstract
The generation of organismal form - morphogenesis - arises from forces produced at the cellular level. In animal cells, much of this force is produced by the actin cytoskeleton. Here, we review how mechanisms of actin-based force generation are deployed during animal morphogenesis to sculpt organs and organisms. Furthermore, we consider how cytoskeletal forces are coupled through cell adhesions to propagate across tissues, and discuss cases where cytoskeletal force or adhesion is patterned across a tissue to direct shape changes. Together, our review provides a conceptual framework that reflects our current understanding of animal morphogenesis and gives perspectives on future opportunities for study.
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Affiliation(s)
- D Nathaniel Clarke
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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16
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Shard C, Luna-Escalante J, Schweisguth F. Tissue-wide coordination of epithelium-to-neural stem cell transition in the Drosophila optic lobe requires Neuralized. J Cell Biol 2021; 219:152101. [PMID: 32946560 PMCID: PMC7594497 DOI: 10.1083/jcb.202005035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/06/2020] [Accepted: 08/17/2020] [Indexed: 12/15/2022] Open
Abstract
Many tissues are produced by specialized progenitor cells emanating from epithelia via epithelial-to-mesenchymal transition (EMT). Most studies have so far focused on EMT involving single or isolated groups of cells. Here we describe an EMT-like process that requires tissue-level coordination. This EMT-like process occurs along a continuous front in the Drosophila optic lobe neuroepithelium to produce neural stem cells (NSCs). We find that emerging NSCs remain epithelial and apically constrict before dividing asymmetrically to produce neurons. Apical constriction is associated with contractile myosin pulses and involves RhoGEF3 and down-regulation of the Crumbs complex by the E3 ubiquitin ligase Neuralized. Anisotropy in Crumbs complex levels also results in accumulation of junctional myosin. Disrupting the regulation of Crumbs by Neuralized lowered junctional myosin and led to imprecision in the integration of emerging NSCs into the front. Thus, Neuralized promotes smooth progression of the differentiation front by coupling epithelium remodeling at the tissue level with NSC fate acquisition.
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Affiliation(s)
- Chloé Shard
- Institut Pasteur, Paris, France.,UMR3738, Centre National de la Recherche Scientifique, Paris, France
| | - Juan Luna-Escalante
- Institut Pasteur, Paris, France.,UMR3738, Centre National de la Recherche Scientifique, Paris, France.,Laboratoire de Physique, Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Sorbonne Université, Université Paris Diderot, Paris, France
| | - François Schweisguth
- Institut Pasteur, Paris, France.,UMR3738, Centre National de la Recherche Scientifique, Paris, France
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17
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Bhagavatula S, Knust E. A putative stem-loop structure in Drosophila crumbs is required for mRNA localisation in epithelia and germline cells. J Cell Sci 2021; 134:224086. [PMID: 33310910 DOI: 10.1242/jcs.236497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 11/30/2020] [Indexed: 01/02/2023] Open
Abstract
Crumbs (Crb) is an evolutionarily conserved transmembrane protein localised to the apical membrane of epithelial cells. Loss or mislocalisation of Crb is often associated with disruption of apicobasal cell polarity. crb mRNA is also apically enriched in epithelial cells, and, as shown here, accumulates in the oocyte of developing egg chambers. We narrowed down the localisation element (LE) of crb mRNA to 47 nucleotides, which form a putative stem-loop structure that may be recognised by Egalitarian (Egl). Mutations in conserved nucleotides abrogate apical transport. crb mRNA enrichment in the oocyte is affected in egl mutant egg chambers. A CRISPR-based genomic deletion of the crb locus that includes the LE disrupts asymmetric crb mRNA localisation in epithelia and prevents its accumulation in the oocyte during early stages of oogenesis, but does not affect Crb protein localisation in embryonic and follicular epithelia. However, flies lacking the LE show ectopic Crb protein expression in the nurse cells. These data suggest an additional role for the Drosophila 3'-UTR in regulating translation in a tissue-specific manner.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Srija Bhagavatula
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max-Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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18
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Perez-Vale KZ, Peifer M. Orchestrating morphogenesis: building the body plan by cell shape changes and movements. Development 2020; 147:dev191049. [PMID: 32917667 PMCID: PMC7502592 DOI: 10.1242/dev.191049] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During embryonic development, a simple ball of cells re-shapes itself into the elaborate body plan of an animal. This requires dramatic cell shape changes and cell movements, powered by the contractile force generated by actin and myosin linked to the plasma membrane at cell-cell and cell-matrix junctions. Here, we review three morphogenetic events common to most animals: apical constriction, convergent extension and collective cell migration. Using the fruit fly Drosophila as an example, we discuss recent work that has revealed exciting new insights into the molecular mechanisms that allow cells to change shape and move without tearing tissues apart. We also point out parallel events at work in other animals, which suggest that the mechanisms underlying these morphogenetic processes are conserved.
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Affiliation(s)
- Kia Z Perez-Vale
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Mark Peifer
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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19
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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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20
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Ko CS, Kalakuntla P, Martin AC. Apical Constriction Reversal upon Mitotic Entry Underlies Different Morphogenetic Outcomes of Cell Division. Mol Biol Cell 2020; 31:1663-1674. [PMID: 32129704 PMCID: PMC7521848 DOI: 10.1091/mbc.e19-12-0673] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
During development, coordinated cell shape changes and cell divisions sculpt tissues. While these individual cell behaviors have been extensively studied, how cell shape changes and cell divisions that occur concurrently in epithelia influence tissue shape is less understood. We addressed this question in two contexts of the early Drosophila embryo: premature cell division during mesoderm invagination, and native ectodermal cell divisions with ectopic activation of apical contractility. Using quantitative live-cell imaging, we demonstrated that mitotic entry reverses apical contractility by interfering with medioapical RhoA signaling. While premature mitotic entry inhibits mesoderm invagination, which relies on apical constriction, mitotic entry in an artificially contractile ectoderm induced ectopic tissue invaginations. Ectopic invaginations resulted from medioapical myosin loss in neighboring mitotic cells. This myosin loss enabled nonmitotic cells to apically constrict through mitotic cell stretching. Thus, the spatial pattern of mitotic entry can differentially regulate tissue shape through signal interference between apical contractility and mitosis.
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Affiliation(s)
- Clint S Ko
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Prateek Kalakuntla
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
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21
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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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22
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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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23
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Abstract
Drosophila melanogaster embryos develop initially as a syncytium of totipotent nuclei and subsequently, once cellularized, undergo morphogenetic movements associated with gastrulation to generate the three somatic germ layers of the embryo: mesoderm, ectoderm, and endoderm. In this chapter, we focus on the first phase of gastrulation in Drosophila involving patterning of early embryos when cells differentiate their gene expression programs. This patterning process requires coordination of multiple developmental processes including genome reprogramming at the maternal-to-zygotic transition, combinatorial action of transcription factors to support distinct gene expression, and dynamic feedback between this genetic patterning by transcription factors and changes in cell morphology. We discuss the gene regulatory programs acting during patterning to specify the three germ layers, which involve the regulation of spatiotemporal gene expression coupled to physical tissue morphogenesis.
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Affiliation(s)
- Angelike Stathopoulos
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
| | - Susan Newcomb
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, United States
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24
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Aguilar G, Matsuda S, Vigano MA, Affolter M. Using Nanobodies to Study Protein Function in Developing Organisms. Antibodies (Basel) 2019; 8:E16. [PMID: 31544822 PMCID: PMC6640693 DOI: 10.3390/antib8010016] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 01/30/2019] [Accepted: 02/01/2019] [Indexed: 12/28/2022] Open
Abstract
Polyclonal and monoclonal antibodies have been invaluable tools to study proteins over the past decades. While indispensable for most biological studies including developmental biology, antibodies have been used mostly in fixed tissues or as binding reagents in the extracellular milieu. For functional studies and for clinical applications, antibodies have been functionalized by covalently fusing them to heterologous partners (i.e., chemicals, proteins or other moieties). Such functionalized antibodies have been less widely used in developmental biology studies. In the past few years, the discovery and application of small functional binding fragments derived from single-chain antibodies, so-called nanobodies, has resulted in novel approaches to study proteins during the development of multicellular animals in vivo. Expression of functionalized nanobody fusions from integrated transgenes allows manipulating proteins of interest in the extracellular and the intracellular milieu in a tissue- and time-dependent manner in an unprecedented manner. Here, we describe how nanobodies have been used in the field of developmental biology and look into the future to imagine how else nanobody-based reagents could be further developed to study the proteome in living organisms.
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Affiliation(s)
- Gustavo Aguilar
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
| | - Shinya Matsuda
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
| | - M Alessandra Vigano
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
| | - Markus Affolter
- Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
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25
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Mathematical Modeling of Tissue Folding and Asymmetric Tissue Flow during Epithelial Morphogenesis. Symmetry (Basel) 2019. [DOI: 10.3390/sym11010113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Recent studies have revealed that intrinsic, individual cell behavior can provide the driving force for deforming a two-dimensional cell sheet to a three-dimensional tissue without the need for external regulatory elements. However, whether intrinsic, individual cell behavior could actually generate the force to induce tissue deformation was unclear, because there was no experimental method with which to verify it in vivo. In such cases, mathematical modeling can be effective for verifying whether a locally generated force can propagate through an entire tissue and induce deformation. Moreover, the mathematical model sometimes provides potential mechanistic insight beyond the information obtained from biological experimental results. Here, we present two examples of modeling tissue morphogenesis driven by cell deformation or cell interaction. In the first example, a mathematical study on tissue-autonomous folding based on a two-dimensional vertex model revealed that active modulations of cell mechanics along the basal–lateral surface, in addition to the apical side, can induce tissue-fold formation. In the second example, by applying a two-dimensional vertex model in an apical plane, a novel mechanism of tissue flow caused by asymmetric cell interactions was discovered, which explained the mechanics behind the collective cellular movement observed during epithelial morphogenesis.
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26
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Quantitative Control of GPCR Organization and Signaling by Endocytosis in Epithelial Morphogenesis. Curr Biol 2018; 28:1570-1584.e6. [PMID: 29731302 DOI: 10.1016/j.cub.2018.03.068] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/16/2018] [Accepted: 03/29/2018] [Indexed: 02/06/2023]
Abstract
Tissue morphogenesis arises from controlled cell deformations in response to cellular contractility. During Drosophila gastrulation, apical activation of the actomyosin networks drives apical constriction in the invaginating mesoderm and cell-cell intercalation in the extending ectoderm. Myosin II (MyoII) is activated by cell-surface G protein-coupled receptors (GPCRs), such as Smog and Mist, that activate G proteins, the small GTPase Rho1, and the kinase Rok. Quantitative control over GPCR and Rho1 activation underlies differences in deformation of mesoderm and ectoderm cells. We show that GPCR Smog activity is concentrated on two different apical plasma membrane compartments, i.e., the surface and plasma membrane invaginations. Using fluorescence correlation spectroscopy, we probe the surface of the plasma membrane, and we show that Smog homo-clusters in response to its activating ligand Fog. Endocytosis of Smog is regulated by the kinase Gprk2 and β-arrestin-2 that clears active Smog from the plasma membrane. When Fog concentration is high or endocytosis is low, Smog rearranges in homo-clusters and accumulates in plasma membrane invaginations that are hubs for Rho1 activation. Lastly, we find higher Smog homo-cluster concentration and numerous apical plasma membrane invaginations in the mesoderm compared to the ectoderm, indicative of reduced endocytosis. We identify that dynamic partitioning of active Smog at the surface of the plasma membrane or plasma membrane invaginations has a direct impact on Rho1 signaling. Plasma membrane invaginations accumulate high Rho1-guanosine triphosphate (GTP) suggesting they form signaling centers. Thus, Fog concentration and Smog endocytosis form coupled regulatory processes that regulate differential Rho1 and MyoII activation in the Drosophila embryo.
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