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Huang Y, Yu G, Yang Y. MIGGRI: A multi-instance graph neural network model for inferring gene regulatory networks for Drosophila from spatial expression images. PLoS Comput Biol 2023; 19:e1011623. [PMID: 37939200 PMCID: PMC10659162 DOI: 10.1371/journal.pcbi.1011623] [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: 04/02/2023] [Revised: 11/20/2023] [Accepted: 10/22/2023] [Indexed: 11/10/2023] Open
Abstract
Recent breakthrough in spatial transcriptomics has brought great opportunities for exploring gene regulatory networks (GRNs) from a brand-new perspective. Especially, the local expression patterns and spatio-temporal regulation mechanisms captured by spatial expression images allow more delicate delineation of the interplay between transcript factors and their target genes. However, the complexity and size of spatial image collections pose significant challenges to GRN inference using image-based methods. Extracting regulatory information from expression images is difficult due to the lack of supervision and the multi-instance nature of the problem, where a gene often corresponds to multiple images captured from different views. While graph models, particularly graph neural networks, have emerged as a promising method for leveraging underlying structure information from known GRNs, incorporating expression images into graphs is not straightforward. To address these challenges, we propose a two-stage approach, MIGGRI, for capturing comprehensive regulatory patterns from image collections for each gene and known interactions. Our approach involves a multi-instance graph neural network (GNN) model for GRN inference, which first extracts gene regulatory features from spatial expression images via contrastive learning, and then feeds them to a multi-instance GNN for semi-supervised learning. We apply our approach to a large set of Drosophila embryonic spatial gene expression images. MIGGRI achieves outstanding performance in the inference of GRNs for early eye development and mesoderm development of Drosophila, and shows robustness in the scenarios of missing image information. Additionally, we perform interpretable analysis on image reconstruction and functional subgraphs that may reveal potential pathways or coordinate regulations. By leveraging the power of graph neural networks and the information contained in spatial expression images, our approach has the potential to advance our understanding of gene regulation in complex biological systems.
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Affiliation(s)
- Yuyang Huang
- Department of Computer Science and Engineering, Shanghai Jiao Tong University, and Key Laboratory of Shanghai Education Commission for Intelligent Interaction and Cognitive Engineering, Shanghai, China
| | - Gufeng Yu
- Department of Computer Science and Engineering, Shanghai Jiao Tong University, and Key Laboratory of Shanghai Education Commission for Intelligent Interaction and Cognitive Engineering, Shanghai, China
| | - Yang Yang
- Department of Computer Science and Engineering, Shanghai Jiao Tong University, and Key Laboratory of Shanghai Education Commission for Intelligent Interaction and Cognitive Engineering, Shanghai, China
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2
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Notch-dependent Abl signaling regulates cell motility during ommatidial rotation in Drosophila. Cell Rep 2022; 41:111788. [PMID: 36476875 PMCID: PMC9887719 DOI: 10.1016/j.celrep.2022.111788] [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: 06/23/2022] [Revised: 09/19/2022] [Accepted: 11/15/2022] [Indexed: 12/12/2022] Open
Abstract
A collective cell motility event that occurs during Drosophila eye development, ommatidial rotation (OR), serves as a paradigm for signaling-pathway-regulated directed movement of cell clusters. OR is instructed by the EGFR and Notch pathways and Frizzled/planar cell polarity (Fz/PCP) signaling, all of which are associated with photoreceptor R3 and R4 specification. Here, we show that Abl kinase negatively regulates OR through its activity in the R3/R4 pair. Abl is localized to apical junctional regions in R4, but not in R3, during OR, and this apical localization requires Notch signaling. We demonstrate that Abl and Notch interact genetically during OR, and Abl co-immunoprecipitates in complexes with Notch in eye discs. Perturbations of Abl interfere with adherens junctional organization of ommatidial preclusters, which mediate the OR process. Together, our data suggest that Abl kinase acts directly downstream of Notch in R4 to fine-tune OR via its effect on adherens junctions.
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3
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Abstract
The molecular complexes underlying planar cell polarity (PCP) were first identified in Drosophila through analysis of mutant phenotypes in the adult cuticle and the orientation of associated polarized protrusions such as wing hairs and sensory bristles. The same molecules are conserved in vertebrates and are required for the localization of polarized protrusions such as primary or sensory cilia and the orientation of hair follicles. Not only is PCP signaling required to align cellular structures across a tissue, it is also required to coordinate movement during embryonic development and adult homeostasis. PCP signaling allows cells to interpret positional cues within a tissue to move in the appropriate direction and to coordinate this movement with their neighbors. In this review we outline the molecular basis of the core Wnt-Frizzled/PCP pathway, and describe how this signaling orchestrates collective motility in Drosophila and vertebrates. Here we cover the paradigms of ommatidial rotation and border cell migration in Drosophila, and convergent extension in vertebrates. The downstream cell biological processes that underlie polarized motility include cytoskeletal reorganization, and adherens junctional and extracellular matrix remodeling. We discuss the contributions of these processes in the respective cell motility contexts. Finally, we address examples of individual cell motility guided by PCP factors during nervous system development and in cancer disease contexts.
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4
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Founounou N, Farhadifar R, Collu GM, Weber U, Shelley MJ, Mlodzik M. Tissue fluidity mediated by adherens junction dynamics promotes planar cell polarity-driven ommatidial rotation. Nat Commun 2021; 12:6974. [PMID: 34848713 PMCID: PMC8632910 DOI: 10.1038/s41467-021-27253-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 11/08/2021] [Indexed: 12/02/2022] Open
Abstract
The phenomenon of tissue fluidity-cells' ability to rearrange relative to each other in confluent tissues-has been linked to several morphogenetic processes and diseases, yet few molecular regulators of tissue fluidity are known. Ommatidial rotation (OR), directed by planar cell polarity signaling, occurs during Drosophila eye morphogenesis and shares many features with polarized cellular migration in vertebrates. We utilize in vivo live imaging analysis tools to quantify dynamic cellular morphologies during OR, revealing that OR is driven autonomously by ommatidial cell clusters rotating in successive pulses within a permissive substrate. Through analysis of a rotation-specific nemo mutant, we demonstrate that precise regulation of junctional E-cadherin levels is critical for modulating the mechanical properties of the tissue to allow rotation to progress. Our study defines Nemo as a molecular tool to induce a transition from solid-like tissues to more viscoelastic tissues broadening our molecular understanding of tissue fluidity.
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Affiliation(s)
- Nabila Founounou
- grid.59734.3c0000 0001 0670 2351Dept. of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029 USA
| | - Reza Farhadifar
- grid.430264.7Center for Computational Biology, Flatiron Institute, Simons Foundation, 162 5th Ave, New York, NY 10010 USA ,grid.38142.3c000000041936754XDepartment of Molecular and Cellular Biology, Harvard University, 52 Oxford St, Cambridge, MA 02138 USA
| | - Giovanna M. Collu
- grid.59734.3c0000 0001 0670 2351Dept. of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029 USA
| | - Ursula Weber
- grid.59734.3c0000 0001 0670 2351Dept. of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029 USA
| | - Michael J. Shelley
- grid.430264.7Center for Computational Biology, Flatiron Institute, Simons Foundation, 162 5th Ave, New York, NY 10010 USA ,grid.137628.90000 0004 1936 8753Courant Institute, New York University, 251 Mercer St, New York, NY 10012 USA
| | - Marek Mlodzik
- Dept. of Cell, Developmental, & Regenerative Biology, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY, 10029, USA.
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5
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Strutt H, Strutt D. How do the Fat-Dachsous and core planar polarity pathways act together and independently to coordinate polarized cell behaviours? Open Biol 2021; 11:200356. [PMID: 33561385 PMCID: PMC8061702 DOI: 10.1098/rsob.200356] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Planar polarity describes the coordinated polarization of cells within the plane of a tissue. This is controlled by two main pathways in Drosophila: the Frizzled-dependent core planar polarity pathway and the Fat–Dachsous pathway. Components of both of these pathways become asymmetrically localized within cells in response to long-range upstream cues, and form intercellular complexes that link polarity between neighbouring cells. This review examines if and when the two pathways are coupled, focusing on the Drosophila wing, eye and abdomen. There is strong evidence that the pathways are molecularly coupled in tissues that express a specific isoform of the core protein Prickle, namely Spiny-legs. However, in other contexts, the linkages between the pathways are indirect. We discuss how the two pathways act together and independently to mediate a diverse range of effects on polarization of cell structures and behaviours.
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Affiliation(s)
- Helen Strutt
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - David Strutt
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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6
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DeAngelis MW, Coolon JD, Johnson RI. Comparative transcriptome analyses of the Drosophila pupal eye. G3-GENES GENOMES GENETICS 2021; 11:5995320. [PMID: 33561221 PMCID: PMC8043229 DOI: 10.1093/g3journal/jkaa003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/08/2020] [Indexed: 12/04/2022]
Abstract
Tissue function is dependent on correct cellular organization and behavior. As a result, the identification and study of genes that contribute to tissue morphogenesis is of paramount importance to the fields of cell and developmental biology. Many of the genes required for tissue patterning and organization are highly conserved between phyla. This has led to the emergence of several model organisms and developmental systems that are used to study tissue morphogenesis. One such model is the Drosophila melanogaster pupal eye that has a highly stereotyped arrangement of cells. In addition, the pupal eye is postmitotic that allows for the study of tissue morphogenesis independent from any effects of proliferation. While the changes in cell morphology and organization that occur throughout pupal eye development are well documented, less is known about the corresponding transcriptional changes that choreograph these processes. To identify these transcriptional changes, we dissected wild-type Canton S pupal eyes and performed RNA-sequencing. Our analyses identified differential expression of many loci that are documented regulators of pupal eye morphogenesis and contribute to multiple biological processes including signaling, axon projection, adhesion, and cell survival. We also identified differential expression of genes not previously implicated in pupal eye morphogenesis such as components of the Toll pathway, several non-classical cadherins, and components of the muscle sarcomere, which could suggest these loci function as novel patterning factors.
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Affiliation(s)
- Miles W DeAngelis
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Joseph D Coolon
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Ruth I Johnson
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
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7
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Koca Y, Housden BE, Gault WJ, Bray SJ, Mlodzik M. Notch signaling coordinates ommatidial rotation in the Drosophila eye via transcriptional regulation of the EGF-Receptor ligand Argos. Sci Rep 2019; 9:18628. [PMID: 31819141 PMCID: PMC6901570 DOI: 10.1038/s41598-019-55203-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 11/24/2019] [Indexed: 02/02/2023] Open
Abstract
In all metazoans, a small number of evolutionarily conserved signaling pathways are reiteratively used during development to orchestrate critical patterning and morphogenetic processes. Among these, Notch (N) signaling is essential for most aspects of tissue patterning where it mediates the communication between adjacent cells to control cell fate specification. In Drosophila, Notch signaling is required for several features of eye development, including the R3/R4 cell fate choice and R7 specification. Here we show that hypomorphic alleles of Notch, belonging to the Nfacet class, reveal a novel phenotype: while photoreceptor specification in the mutant ommatidia is largely normal, defects are observed in ommatidial rotation (OR), a planar cell polarity (PCP)-mediated cell motility process. We demonstrate that during OR Notch signaling is specifically required in the R4 photoreceptor to upregulate the transcription of argos (aos), an inhibitory ligand to the epidermal growth factor receptor (EGFR), to fine-tune the activity of EGFR signaling. Consistently, the loss-of-function defects of Nfacet alleles and EGFR-signaling pathway mutants are largely indistinguishable. A Notch-regulated aos enhancer confers R4 specific expression arguing that aos is directly regulated by Notch signaling in this context via Su(H)-Mam-dependent transcription.
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Affiliation(s)
- Yildiz Koca
- 0000 0001 0670 2351grid.59734.3cDept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,0000 0001 0670 2351grid.59734.3cGraduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA
| | - Benjamin E. Housden
- 0000000121885934grid.5335.0Dept. of Physiology, Development and Neuroscience, University of Cambridge Downing Street, Cambridge, CB2 3DY UK ,0000 0004 1936 8024grid.8391.3Present Address: Living Systems Institute, University of Exeter, Exeter, EX4 4QD UK
| | - William J. Gault
- 0000 0001 0670 2351grid.59734.3cDept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,0000 0001 0670 2351grid.59734.3cGraduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,0000 0001 2264 7145grid.254250.4Present Address: City College of New York, 160 Convert Ave, New York, NY USA
| | - Sarah J. Bray
- 0000000121885934grid.5335.0Dept. of Physiology, Development and Neuroscience, University of Cambridge Downing Street, Cambridge, CB2 3DY UK
| | - Marek Mlodzik
- 0000 0001 0670 2351grid.59734.3cDept. of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,0000 0001 0670 2351grid.59734.3cGraduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA
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8
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Thuveson M, Gaengel K, Collu GM, Chin ML, Singh J, Mlodzik M. Integrins are required for synchronous ommatidial rotation in the Drosophila eye linking planar cell polarity signalling to the extracellular matrix. Open Biol 2019; 9:190148. [PMID: 31409231 PMCID: PMC6731590 DOI: 10.1098/rsob.190148] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Integrins mediate the anchorage between cells and their environment, the extracellular matrix (ECM), and form transmembrane links between the ECM and the cytoskeleton, a conserved feature throughout development and morphogenesis of epithelial organs. Here, we demonstrate that integrins and components of the ECM are required during the planar cell polarity (PCP) signalling-regulated cell movement of ommatidial rotation in the Drosophila eye. The loss-of-function mutations of integrins or ECM components cause defects in rotation, with mutant clusters rotating asynchronously compared to wild-type clusters. Initially, mutant clusters tend to rotate faster, and at later stages they fail to be synchronous with their neighbours, leading to aberrant rotation angles and resulting in a disorganized ommatidial arrangement in adult eyes. We further demonstrate that integrin localization changes dynamically during the rotation process. Our data suggest that core Frizzled/PCP factors, acting through RhoA and Rho kinase, regulate the function/activity of integrins and that integrins thus contribute to the complex interaction network of PCP signalling, cell adhesion and cytoskeletal elements required for a precise and synchronous 90° rotation movement.
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Affiliation(s)
- Maria Thuveson
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Konstantin Gaengel
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA.,Department of Immunology, Genetics and Pathology, Uppsala University, Rudbeck Laboratory C11, Dag Hammarskjölds Väg 20, 751 85 Uppsala, Sweden
| | - Giovanna M Collu
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Mei-Ling Chin
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Jaskirat Singh
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Marek Mlodzik
- Department of Cell, Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, Annenberg Building 18-92, One Gustave L. Levy Place, New York, NY 10029, USA
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9
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Bigenzahn JW, Collu GM, Kartnig F, Pieraks M, Vladimer GI, Heinz LX, Sedlyarov V, Schischlik F, Fauster A, Rebsamen M, Parapatics K, Blomen VA, Müller AC, Winter GE, Kralovics R, Brummelkamp TR, Mlodzik M, Superti-Furga G. LZTR1 is a regulator of RAS ubiquitination and signaling. Science 2018; 362:1171-1177. [PMID: 30442766 DOI: 10.1126/science.aap8210] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 06/26/2018] [Accepted: 10/30/2018] [Indexed: 12/12/2022]
Abstract
In genetic screens aimed at understanding drug resistance mechanisms in chronic myeloid leukemia cells, inactivation of the cullin 3 adapter protein-encoding leucine zipper-like transcription regulator 1 (LZTR1) gene led to enhanced mitogen-activated protein kinase (MAPK) pathway activity and reduced sensitivity to tyrosine kinase inhibitors. Knockdown of the Drosophila LZTR1 ortholog CG3711 resulted in a Ras-dependent gain-of-function phenotype. Endogenous human LZTR1 associates with the main RAS isoforms. Inactivation of LZTR1 led to decreased ubiquitination and enhanced plasma membrane localization of endogenous KRAS (V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog). We propose that LZTR1 acts as a conserved regulator of RAS ubiquitination and MAPK pathway activation. Because LZTR1 disease mutations failed to revert loss-of-function phenotypes, our findings provide a molecular rationale for LZTR1 involvement in a variety of inherited and acquired human disorders.
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Affiliation(s)
- Johannes W Bigenzahn
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Giovanna M Collu
- Department of Cell, Developmental, and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY 10029, USA
| | - Felix Kartnig
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Melanie Pieraks
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Gregory I Vladimer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Leonhard X Heinz
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Vitaly Sedlyarov
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Fiorella Schischlik
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Astrid Fauster
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria.,Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands
| | - Manuele Rebsamen
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Katja Parapatics
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Vincent A Blomen
- Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands
| | - André C Müller
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Georg E Winter
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Robert Kralovics
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria.,Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Thijn R Brummelkamp
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria.,Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands.,Oncode Institute, Division of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands.,Cancer Genomics Center (CGC.nl), Plesmanlaan 121, 1066 CX, Amsterdam, Netherlands
| | - Marek Mlodzik
- Department of Cell, Developmental, and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY 10029, USA
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria. .,Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
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10
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Veeman MT, McDonald JA. Dynamics of cell polarity in tissue morphogenesis: a comparative view from Drosophila and Ciona. F1000Res 2016; 5. [PMID: 27303647 PMCID: PMC4892338 DOI: 10.12688/f1000research.8011.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/31/2016] [Indexed: 12/16/2022] Open
Abstract
Tissues in developing embryos exhibit complex and dynamic rearrangements that shape forming organs, limbs, and body axes. Directed migration, mediolateral intercalation, lumen formation, and other rearrangements influence the topology and topography of developing tissues. These collective cell behaviors are distinct phenomena but all involve the fine-grained control of cell polarity. Here we review recent findings in the dynamics of polarized cell behavior in both the
Drosophila ovarian border cells and the
Ciona notochord. These studies reveal the remarkable reorganization of cell polarity during organ formation and underscore conserved mechanisms of developmental cell polarity including the Par/atypical protein kinase C (aPKC) and planar cell polarity pathways. These two very different model systems demonstrate important commonalities but also key differences in how cell polarity is controlled in tissue morphogenesis. Together, these systems raise important, broader questions on how the developmental control of cell polarity contributes to morphogenesis of diverse tissues across the metazoa.
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Affiliation(s)
- Michael T Veeman
- Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA
| | - Jocelyn A McDonald
- Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA
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11
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Malartre M. Regulatory mechanisms of EGFR signalling during Drosophila eye development. Cell Mol Life Sci 2016; 73:1825-43. [PMID: 26935860 PMCID: PMC11108404 DOI: 10.1007/s00018-016-2153-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/20/2016] [Accepted: 02/01/2016] [Indexed: 01/14/2023]
Abstract
EGFR signalling is a well-conserved signalling pathway playing major roles during development and cancers. This review explores what studying the EGFR pathway during Drosophila eye development has taught us in terms of the diversity of its regulatory mechanisms. This model system has allowed the identification of numerous positive and negative regulators acting at specific time and place, thus participating to the tight control of signalling. EGFR signalling regulation is achieved by a variety of mechanisms, including the control of ligand processing, the availability of the receptor itself and the transduction of the cascade in the cytoplasm. Ultimately, the transcriptional responses contribute to the establishment of positive and negative feedback loops. The combination of these multiple mechanisms employed to regulate the EGFR pathway leads to specific cellular outcomes involved in functions as diverse as the acquisition of cell fate, proliferation, survival, adherens junction remodelling and morphogenesis.
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Affiliation(s)
- Marianne Malartre
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France.
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12
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Unique and Overlapping Functions of Formins Frl and DAAM During Ommatidial Rotation and Neuronal Development in Drosophila. Genetics 2016; 202:1135-51. [PMID: 26801180 DOI: 10.1534/genetics.115.181438] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 01/18/2016] [Indexed: 01/14/2023] Open
Abstract
The noncanonical Frizzled/planar cell polarity (PCP) pathway regulates establishment of polarity within the plane of an epithelium to generate diversity of cell fates, asymmetric, but highly aligned structures, or to orchestrate the directional migration of cells during convergent extension during vertebrate gastrulation. In Drosophila, PCP signaling is essential to orient actin wing hairs and to align ommatidia in the eye, in part by coordinating the movement of groups of photoreceptor cells during ommatidial rotation. Importantly, the coordination of PCP signaling with changes in the cytoskeleton is essential for proper epithelial polarity. Formins polymerize linear actin filaments and are key regulators of the actin cytoskeleton. Here, we show that the diaphanous-related formin, Frl, the single fly member of the FMNL (formin related in leukocytes/formin-like) formin subfamily affects ommatidial rotation in the Drosophila eye and is controlled by the Rho family GTPase Cdc42. Interestingly, we also found that frl mutants exhibit an axon growth phenotype in the mushroom body, a center for olfactory learning in the Drosophila brain, which is also affected in a subset of PCP genes. Significantly, Frl cooperates with Cdc42 and another formin, DAAM, during mushroom body formation. This study thus suggests that different formins can cooperate or act independently in distinct tissues, likely integrating various signaling inputs with the regulation of the cytoskeleton. It furthermore highlights the importance and complexity of formin-dependent cytoskeletal regulation in multiple organs and developmental contexts.
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13
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Muñoz-Soriano V, Santos D, Durupt FC, Casani S, Paricio N. Scabrous overexpression in the eye affects R3/R4 cell fate specification and inhibits notch signaling. Dev Dyn 2015; 245:166-74. [PMID: 26505171 DOI: 10.1002/dvdy.24362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 10/07/2015] [Accepted: 10/23/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Planar cell polarity (PCP) in the Drosophila eye is generated when immature ommatidial preclusters acquire opposite chirality in the dorsal and ventral halves of the eye imaginal disc and rotate 90 ° toward the equator. The scabrous (sca) gene is involved in R8 differentiation and in the correct spacing of ommatidial clusters in eye imaginal discs, but it was also suggested to be required during ommatidial rotation. However, no clear relationships between sca and other genes involved in the process were established. RESULTS To explore the role of Sca in PCP establishment, we performed an RNAi-based modifier genetic screen using the rough eye phenotype of sca-overexpressing flies. We found that sca overexpression mainly affects R3/R4 cell specification as it was reported in Notch mutants. Of the 86 modifiers identified in the screen, genes encoding components of Notch signaling and proteins involved in intracellular transport were of particular interest. CONCLUSIONS These and other results obtained with a reporter line of Notch activity indicate that sca overexpression antagonizes Notch signaling in the Drosophila eye, and are inconsistent with Sca being an ommatidial rotation-specific factor. We also found that microtubule motors and other proteins involved in intracellular transport are related with Sca function.
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Affiliation(s)
- Verónica Muñoz-Soriano
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain.,Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universidad de Valencia, Burjasot, Spain
| | - Diego Santos
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain
| | - Fabrice C Durupt
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universidad de Valencia, Burjasot, Spain
| | - Sandra Casani
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain
| | - Nuria Paricio
- Departamento de Genética, Facultad CC Biológicas, Universidad de Valencia, Burjasot, Spain.,Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universidad de Valencia, Burjasot, Spain
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14
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Singh J, Mlodzik M. Planar cell polarity signaling: coordination of cellular orientation across tissues. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 1:479-99. [PMID: 23066429 DOI: 10.1002/wdev.32] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Establishment of Planar Cell Polarity (PCP) in epithelia, in the plane of an epithelium, is an important feature of the development and homeostasis of most organs. Studies in different model organisms have contributed a wealth of information regarding the mechanisms that govern PCP regulation. Genetic studies in Drosophila have identified two signaling systems, the Fz/PCP and Fat/Dachsous system, which are both required for PCP establishment in many different tissues in a largely non-redundant manner. Recent advances in vertebrate PCP studies have added novel factors of PCP regulation and also new cellular features requiring PCP-signaling input, including the positioning and orientation of the primary cilium of many epithelial cells. This review focuses mostly on several recent advances made in the Drosophila and vertebrate PCP field and integrates these within the existing PCP-signaling framework.
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Affiliation(s)
- Jaskirat Singh
- Department of Developmental & Regenerative Biology, Mount Sinai School of Medicine, New York, NY, USA
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15
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Transcriptional regulation of tissue organization and cell morphogenesis: the fly retina as a case study. Dev Biol 2013; 385:168-78. [PMID: 24099926 DOI: 10.1016/j.ydbio.2013.09.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 09/27/2013] [Accepted: 09/29/2013] [Indexed: 12/11/2022]
Abstract
Understanding how a functional organ can be produced from a small group of cells remains an outstanding question in cell and developmental biology. The developing compound eye of Drosophila has long been a model of choice for addressing this question by dissecting the cellular, genetic and molecular pathways that govern cell specification, differentiation, and multicellular patterning during organogenesis. In this review, the author focussed on cell and tissue morphogenesis during fly retinal development, including the regulated changes in cell shape and cell packing that ultimately determine the shape and architecture of the compound eye. In particular, the author reviewed recent studies that highlight the prominent roles of transcriptional and hormonal controls that orchestrate the cell shape changes, cell-cell junction remodeling and polarized membrane growth that underlie photoreceptor morphogenesis and retinal patterning.
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16
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Muñoz-Soriano V, Ruiz C, Pérez-Alonso M, Mlodzik M, Paricio N. Nemo regulates cell dynamics and represses the expression of miple, a midkine/pleiotrophin cytokine, during ommatidial rotation. Dev Biol 2013; 377:113-25. [PMID: 23428616 DOI: 10.1016/j.ydbio.2013.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 02/07/2013] [Accepted: 02/11/2013] [Indexed: 01/18/2023]
Abstract
Ommatidial rotation is one of the most important events for correct patterning of the Drosophila eye. Although several signaling pathways are involved in this process, few genes have been shown to specifically affect it. One of them is nemo (nmo), which encodes a MAP-like protein kinase that regulates the rate of rotation throughout the entire process, and serves as a link between core planar cell polarity (PCP) factors and the E-cadherin-β-catenin complex. To determine more precisely the role of nmo in ommatidial rotation, live-imaging analyses in nmo mutant and wild-type early pupal eye discs were performed. We demonstrate that ommatidial rotation is not a continuous process, and that rotating and non-rotating interommatidial cells are very dynamic. Our in vivo analyses also show that nmo regulates the speed of rotation and is required in cone cells for correct ommatidial rotation, and that these cells as well as interommatidial cells are less dynamic in nmo mutants. Furthermore, microarray analyses of nmo and wild-type larval eye discs led us to identify new genes and signaling pathways related to nmo function during this process. One of them, miple, encodes the Drosophila ortholog of the midkine/pleiotrophin secreted cytokines that are involved in cell migration processes. miple is highly up-regulated in nmo mutant discs. Indeed, phenotypic analyses reveal that miple overexpression leads to ommatidial rotation defects. Genetic interaction assays suggest that miple is signaling through Ptp99A, the Drosophila ortholog of the vertebrate midkine/pleiotrophin PTPζ receptor. Accordingly, we propose that one of the roles of Nmo during ommatial rotation is to repress miple expression, which may in turn affect the dynamics in E-cadherin-β-catenin complexes.
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Affiliation(s)
- Verónica Muñoz-Soriano
- Departamento de Genética, Facultad de CC Biológicas, Universidad de Valencia, Doctor Moliner 50, E-46100 Burjassot, Valencia, Spain
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17
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Abstract
In all multicellular organisms, epithelial cells are not only polarized along the apical-basal axis, but also within the epithelial plane, giving cells a sense of direction. Planar cell polarity (PCP) signaling regulates establishment of polarity within the plane of an epithelium. The outcomes of PCP signaling are diverse and include the determination of cell fates, the generation of asymmetric but highly aligned structures, such as the stereocilia in the human inner ear or the hairs on a fly wing, or the directional migration of cells during convergence and extension during vertebrate gastrulation. In humans, aberrant PCP signaling can result in severe developmental defects, such as open neural tubes (spina bifida), and can cause cystic kidneys. In this review, we discuss the basic mechanism and more recent findings of PCP signaling focusing on Drosophila melanogaster, the model organism in which most key PCP components were initially identified.
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Affiliation(s)
- Saw Myat Thanda W Maung
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, New York, NY, USA
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18
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Nemo kinase phosphorylates β-catenin to promote ommatidial rotation and connects core PCP factors to E-cadherin-β-catenin. Nat Struct Mol Biol 2011; 18:665-72. [PMID: 21552260 PMCID: PMC3109122 DOI: 10.1038/nsmb.2049] [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: 05/03/2010] [Accepted: 02/17/2011] [Indexed: 01/13/2023]
Abstract
Frizzled planar cell polarity (PCP) signaling regulates cell motility in several tissues, including ommatidial rotation in Drosophila melanogaster. The Nemo kinase (Nlk in vertebrates) has also been linked to cell-motility regulation and ommatidial rotation but its mechanistic role(s) during rotation remain obscure. We show that nemo functions throughout the entire rotation movement, increasing the rotation rate. Genetic and molecular studies indicate that Nemo binds both the core PCP factor complex of Strabismus-Prickle, as well as the E-cadherin-β-catenin (E-cadherin-Armadillo in Drosophila) complex. These two complexes colocalize and, like Nemo, also promote rotation. Strabismus (also called Vang) binds and stabilizes Nemo asymmetrically within the ommatidial precluster; Nemo and β-catenin then act synergistically to promote rotation, which is mediated in vivo by Nemo's phosphorylation of β-catenin. Our data suggest that Nemo serves as a conserved molecular link between core PCP factors and E-cadherin-β-catenin complexes, promoting cell motility.
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19
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Yu L, Lee T, Lin N, Wolf MJ. Affecting Rhomboid-3 function causes a dilated heart in adult Drosophila. PLoS Genet 2010; 6:e1000969. [PMID: 20523889 PMCID: PMC2877733 DOI: 10.1371/journal.pgen.1000969] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 04/23/2010] [Indexed: 11/18/2022] Open
Abstract
Drosophila is a well recognized model of several human diseases, and recent investigations have demonstrated that Drosophila can be used as a model of human heart failure. Previously, we described that optical coherence tomography (OCT) can be used to rapidly examine the cardiac function in adult, awake flies. This technique provides images that are similar to echocardiography in humans, and therefore we postulated that this approach could be combined with the vast resources that are available in the fly community to identify new mutants that have abnormal heart function, a hallmark of certain cardiovascular diseases. Using OCT to examine the cardiac function in adult Drosophila from a set of molecularly-defined genomic deficiencies from the DrosDel and Exelixis collections, we identified an abnormally enlarged cardiac chamber in a series of deficiency mutants spanning the rhomboid 3 locus. Rhomboid 3 is a member of a highly conserved family of intramembrane serine proteases and processes Spitz, an epidermal growth factor (EGF)-like ligand. Using multiple approaches based on the examination of deficiency stocks, a series of mutants in the rhomboid-Spitz-EGF receptor pathway, and cardiac-specific transgenic rescue or dominant-negative repression of EGFR, we demonstrate that rhomboid 3 mediated activation of the EGF receptor pathway is necessary for proper adult cardiac function. The importance of EGF receptor signaling in the adult Drosophila heart underscores the concept that evolutionarily conserved signaling mechanisms are required to maintain normal myocardial function. Interestingly, prior work showing the inhibition of ErbB2, a member of the EGF receptor family, in transgenic knock-out mice or individuals that received herceptin chemotherapy is associated with the development of dilated cardiomyopathy. Our results, in conjunction with the demonstration that altered ErbB2 signaling underlies certain forms of mammalian cardiomyopathy, suggest that an evolutionarily conserved signaling mechanism may be necessary to maintain post-developmental cardiac function.
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Affiliation(s)
- Lin Yu
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Teresa Lee
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
| | - Na Lin
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Matthew J. Wolf
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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20
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Ho YH, Lien MT, Lin CM, Wei SY, Chang LH, Hsu JC. Echinoid regulates Flamingo endocytosis to control ommatidial rotation in the Drosophila eye. Development 2010; 137:745-54. [DOI: 10.1242/dev.040238] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Planar cell polarity (PCP) refers to a second polarity axis orthogonal to the apicobasal axis in the plane of the epithelium. The molecular link between apicobasal polarity and PCP is largely unknown. During Drosophila eye development, differentiated photoreceptors form clusters that rotate independently of the surrounding interommatidial cells (ICs). Here, we demonstrate that both Echinoid (Ed), an adherens junction-associated cell adhesion molecule, and Flamingo (Fmi), a PCP determinant, are endocytosed via a clathrin-mediated pathway in ICs. Interestingly, we found that Ed binds the AP-2 adaptor and is required for the internalization of Fmi into ICs. Loss of ed led to increased amounts of Fmi on the cell membrane of non-rotating ICs and also to the misrotation of photoreceptor clusters. Importantly, overexpression of fmi in ICs alone was sufficient to cause misrotation of the adjacent photoreceptor clusters. Together, we propose that Ed, when internalized by AP-2, undergoes co-endocytosis with, and thereby decreases, Fmi levels on non-rotating ICs to permit correct rotation of ommatidial clusters. Thus, co-endocytosis of Ed and Fmi provides a link between apicobasal polarity and PCP.
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Affiliation(s)
- Yu-Huei Ho
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Mong-Ting Lien
- 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
| | - Shu-Yi Wei
- Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China
| | - Li-Hsun Chang
- 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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21
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Abstract
Planar cell polarity (PCP) signaling regulates the establishment of polarity within the plane of an epithelium and allows cells to obtain directional information. Its results are as diverse as the determination of cell fates, the generation of asymmetric but highly aligned structures (e.g., stereocilia in the human ear or hairs on a fly wing), or the directional migration of cells during convergent extension during vertebrate gastrulation. Aberrant PCP establishment can lead to human birth defects or kidney disease. PCP signaling is governed by the noncanonical Wnt or Fz/PCP pathway. Traditionally, PCP establishment has been best studied in Drosophila, mainly due to the versatility of the fly as a genetic model system. In Drosophila, PCP is essential for the orientation of wing and abdominal hairs, the orientation of the division axis of sensory organ precursors, and the polarization of ommatidia in the eye, the latter requiring a highly coordinated movement of groups of photoreceptor cells during the process of ommatidial rotation. Here, I review our current understanding of PCP signaling in the Drosophila eye and allude to parallels in vertebrates.
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Affiliation(s)
- Andreas Jenny
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, New York, USA
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22
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Fetting JL, Spencer SA, Wolff T. The cell adhesion molecules Echinoid and Friend of Echinoid coordinate cell adhesion and cell signaling to regulate the fidelity of ommatidial rotation in the Drosophila eye. Development 2009; 136:3323-33. [PMID: 19736327 DOI: 10.1242/dev.038422] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Directed cellular movements are a universal feature of morphogenesis in multicellular organisms. Differential adhesion between the stationary and motile cells promotes these cellular movements to effect spatial patterning of cells. A prominent feature of Drosophila eye development is the 90 degrees rotational movement of the multicellular ommatidial precursors within a matrix of stationary cells. We demonstrate that the cell adhesion molecules Echinoid (Ed) and Friend of Echinoid (Fred) act throughout ommatidial rotation to modulate the degree of ommatidial precursor movement. We propose that differential levels of Ed and Fred between stationary and rotating cells at the initiation of rotation create a permissive environment for cell movement, and that uniform levels in these two populations later contribute to stopping the movement. Based on genetic data, we propose that ed and fred impart a second, independent, ;brake-like' contribution to this process via Egfr signaling. Ed and Fred are localized in largely distinct and dynamic patterns throughout rotation. However, ed and fred are required in only a subset of cells - photoreceptors R1, R7 and R6 - for normal rotation, cells that have only recently been linked to a role in planar cell polarity (PCP). This work also provides the first demonstration of a requirement for cone cells in the ommatidial rotation aspect of PCP. ed and fred also genetically interact with the PCP genes, but affect only the degree-of-rotation aspect of the PCP phenotype. Significantly, we demonstrate that at least one PCP protein, Stbm, is required in R7 to control the degree of ommatidial rotation.
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Affiliation(s)
- Jennifer L Fetting
- Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA
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23
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O'Keefe DD, Gonzalez-Niño E, Burnett M, Dylla L, Lambeth SM, Licon E, Amesoli C, Edgar BA, Curtiss J. Rap1 maintains adhesion between cells to affect Egfr signaling and planar cell polarity in Drosophila. Dev Biol 2009; 333:143-60. [PMID: 19576205 DOI: 10.1016/j.ydbio.2009.06.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 06/06/2009] [Accepted: 06/23/2009] [Indexed: 11/19/2022]
Abstract
The small GTPase Rap1 affects cell adhesion and cell motility in numerous developmental contexts. Loss of Rap1 in the Drosophila wing epithelium disrupts adherens junction localization, causing mutant cells to disperse, and dramatically alters epithelial cell shape. While the adhesive consequences of Rap1 inactivation have been well described in this system, the effects on cell signaling, cell fate specification, and tissue differentiation are not known. Here we demonstrate that Egfr-dependent cell types are lost from Rap1 mutant tissue as an indirect consequence of DE-cadherin mislocalization. Cells lacking Rap1 in the developing wing and eye are capable of responding to an Egfr signal, indicating that Rap1 is not required for Egfr/Ras/MAPK signal transduction. Instead, Rap1 regulates adhesive contacts necessary for maintenance of Egfr signaling between cells, and differentiation of wing veins and photoreceptors. Rap1 is also necessary for planar cell polarity in these tissues. Wing hair alignment and ommatidial rotation, functional readouts of planar cell polarity in the wing and eye respectively, are both affected in Rap1 mutant tissue. Finally, we show that Rap1 acts through the effector Canoe to regulate these developmental processes.
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Affiliation(s)
- David D O'Keefe
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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24
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Quintin S, Gally C, Labouesse M. Epithelial morphogenesis in embryos: asymmetries, motors and brakes. Trends Genet 2008; 24:221-30. [PMID: 18375008 DOI: 10.1016/j.tig.2008.02.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 01/30/2008] [Accepted: 02/01/2008] [Indexed: 10/22/2022]
Abstract
Epithelial cells play a central role in many embryonic morphogenetic processes, during which they undergo highly coordinated cell shape changes. Here, we review some common principles that have recently emerged through genetic and cellular analyses performed mainly with invertebrate genetic models, focusing on morphogenetic processes involving epithelial sheets. All available data argue that myosin II is the main motor that induces cell shape changes during morphogenesis. We discuss the control of myosin II activity during epithelial morphogenesis, as well as the recently described involvement of microtubules in this process. Finally, we examine how forces unleashed by myosin II can be measured, how embryos use specific brakes to control molecular motors and the potential input of mechano-sensation in morphogenesis.
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Affiliation(s)
- Sophie Quintin
- IGBMC, CNRS/INSERM/ULP, BP. 10142, 67404 Illkirch Cedex, France
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25
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Yogev S, Schejter ED, Shilo BZ. Drosophila EGFR signalling is modulated by differential compartmentalization of Rhomboid intramembrane proteases. EMBO J 2008; 27:1219-30. [PMID: 18369317 DOI: 10.1038/emboj.2008.58] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 02/29/2008] [Indexed: 11/09/2022] Open
Abstract
We explore the role of differential compartmentalization of Rhomboid (Rho) proteases that process the Drosophila EGF receptor ligands, in modulating the amount of secreted ligand and consequently the level of EGF receptor (EGFR) activation. The mSpitz ligand precursor is retained in the ER, and is trafficked by the chaperone Star to a late compartment of the secretory pathway, where Rho-1 resides. This work demonstrates that two other Rho proteins, Rho-2 and Rho-3, which are expressed in the germ line and in the developing eye, respectively, cleave the Spitz precursor and Star already in the ER, in addition to their activity in the late compartment. This property attenuates EGFR activation, primarily by compromising the amount of chaperone that can productively traffic the ligand precursor to the late compartment, where cleavage and subsequent secretion take place. These observations identify changes in intracellular compartment localization of Rho proteins as a basis for signal attenuation, in tissues where EGFR activation must be highly restricted in space and time.
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Affiliation(s)
- Shaul Yogev
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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26
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Montrasio S, Mlodzik M, Fanto M. A new allele uncovers the role of echinus in the control of ommatidial rotation in the Drosophila eye. Dev Dyn 2008; 236:2936-42. [PMID: 17879315 DOI: 10.1002/dvdy.21328] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The precise orientation of the ommatidia in the Drosophila eye is achieved through a specialized process of cell migration taking place in the third-instar eye imaginal disc when ommatidial clusters rotate by 90 degrees. This process is strictly coordinated with the establishment of planar cell polarity (PCP), but it relies on a specific set of genes that control its mechanism independently from PCP signaling. Recently, the epidermal growth factor receptor (EGFR) pathway has been implicated in determining ommatidial rotation. We have isolated a new allele of echinus, a gene known to control the patterning and number of interommatidial cells. We show that echinus displays defects in the rotation of ommatidia that are not evident until mid-pupal stages, and we propose that echinus action is that of opposing EGFR by an unknown mechanism and that this can explain both its influence in ommatidial rotation and lattice programmed cell death (PCD).
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Affiliation(s)
- Silvia Montrasio
- Dulbecco Telethon Institute, DIBIT, San Raffaele Scientific Institute, Milan, Italy
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27
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Fiehler RW, Wolff T. Nemo is required in a subset of photoreceptors to regulate the speed of ommatidial rotation. Dev Biol 2007; 313:533-44. [PMID: 18068152 DOI: 10.1016/j.ydbio.2007.10.034] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/12/2007] [Accepted: 10/13/2007] [Indexed: 11/18/2022]
Abstract
Both dramatic and subtle morphogenetic movements are of paramount importance in molding cells and tissues into functional form. Cells move either independently or as populations and the distance traversed by cells varies greatly, but in all cases, the output is common: to organize cells into or within organs and epithelia. In the developing Drosophila eye, a highly specialized, 90 degrees rotational movement of subsets of cells imposes order by polarizing the retinal epithelium across its dorsoventral axis. This process was proposed to take place in two 45 degrees steps, with the second under control of the gene nemo (nmo), a serine/threonine kinase. While our analysis confirms that these subsets of cells, the ommatidial precursors, do stall at 45 degrees , we demonstrate that nmo is also required through most of the first 45 degrees of rotation to regulate the speed at which the ommatidial precursors move. In addition, although the precursors reach only the halfway point by the end of larval life, this work demonstrates that patterning events that occur during pupal life move the ommatidial units an additional 15 degrees . A re-analysis of nmo mosaic clones indicates that nmo is required in photoreceptors R1, R6 and R7 for normal orientation. This work also demonstrates that two major isoforms of nmo rescue the nmo(P1) phenotype. Finally, a dominant modifier screen of a nmo misexpression background identified genomic regions that potentially regulate rotation. The results presented here suggest a model in which a motor for rotation is established in a nemo-dependent fashion in a subset of cells.
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Affiliation(s)
- Ryan W Fiehler
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
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28
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Fiehler RW, Wolff T. Drosophila Myosin II, Zipper, is essential for ommatidial rotation. Dev Biol 2007; 310:348-62. [PMID: 17826761 PMCID: PMC2110880 DOI: 10.1016/j.ydbio.2007.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 06/20/2007] [Accepted: 08/01/2007] [Indexed: 01/17/2023]
Abstract
The adult Drosophila retina is a highly polarized epithelium derived from a precursor tissue that is initially symmetric across its dorsoventral axis. Specialized 90 degrees rotational movements of subsets of cells, the ommatidial precursors, establish mirror symmetry in the retinal epithelium. Myosin II, or Zipper (Zip), a motor protein, regulates the rate at which ommatidia rotate: in zip mutants, the rate of rotation is significantly slowed. Zip is concentrated in the cells that we show to be at the likely interface between rotating and non-rotating cells: the boundary between differentiated and undifferentiated cells. Zip is also robust in newly added ommatidial cells, consistent with our model that the machinery that drives rotation should shift to newly recruited cells as they are added to the growing ommatidium. Finally, cell death genes and canonical Wnt signaling pathway members genetically modify the zip phenotype.
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Affiliation(s)
- Ryan W Fiehler
- Department of Genetics, Washington University School of Medicine, St Louis, MO 63110, USA
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29
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Wolff T, Guinto JB, Rawls AS. Screen for genetic modifiers of stbm reveals that photoreceptor fate and rotation can be genetically uncoupled in the Drosophila eye. PLoS One 2007; 2:e453. [PMID: 17505545 PMCID: PMC1866179 DOI: 10.1371/journal.pone.0000453] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Accepted: 04/24/2007] [Indexed: 11/18/2022] Open
Abstract
Background Polarity of the Drosophila compound eye arises primarily as a consequence of two events that are tightly linked in time and space: fate specification of two photoreceptor cells, R3 and R4, and the subsequent directional movement of the unit eyes of the compound eye, or ommatidia. While it is thought that these fates dictate the direction of ommatidial rotation, the phenotype of mutants in the genes that set up this polarity led to the hypothesis that these two events could be uncoupled. Methodology/Principal Findings To definitively demonstrate these events are genetically separable, we conducted a dominant modifier screen to determine if genes, when misexpressed, could selectively enhance subclasses of mutant ommatidia in which the direction of rotation does not follow the R3/R4 cell fates, yet not affect the number of ommatidia in which rotation follows the R3/R4 cell fates. We identified a subset of P element lines that exhibit this selective enhancement. We also identified lines that behave in the opposite manner: They enhance the number of ommatidia that rotate in the right direction, but do not alter the number of ommatidia that rotate incorrectly with respect to the R3/R4 fates. Conclusions/Significance These results indicate that fate and direction of rotation can be genetically separated, and that there are genes that act between R3/R4 fate specification and direction of ommatidial rotation. These data affirm what has been a long-standing assumption about the genetic control of ommatidial polarity.
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Affiliation(s)
- Tanya Wolff
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America.
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30
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Brown KE, Kerr M, Freeman M. The EGFR ligands Spitz and Keren act cooperatively in the Drosophila eye. Dev Biol 2007; 307:105-13. [PMID: 17512517 DOI: 10.1016/j.ydbio.2007.04.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 04/19/2007] [Accepted: 04/20/2007] [Indexed: 01/24/2023]
Abstract
The EGFR signalling cascade is responsible for coordinating a wide variety of events during Drosophila eye development. It remains something of a mystery how it is that cells are able to interpret the signal so as to choose the appropriate response from the battery of possibilities: division, differentiation, cell shape change and so on. Since the cascade is essentially linear below the receptor, different cellular responses cannot be regulated by alternative signal transduction pathways. The main diversity lies upstream, in the multiple activating ligands. Spitz, Gurken and Vein have been long studied, but little is known about the physiological functions of the fourth ligand, Keren, although various roles have been predicted based on the differences between mutants in the known ligands and those of the receptor. Here, we have isolated a mutant in the keren gene, and demonstrate that Keren does indeed participate in EGFR signalling in the eye, where it acts redundantly with Spitz to control R8 spacing, cell clustering and survival. Thus, specificity cannot be determined by ligand choice, and must instead be a consequence of cell-intrinsic factors, although we speculate that there may be some quantitative differences in signalling elicited by the two ligands.
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Affiliation(s)
- Katherine E Brown
- MRC-Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK
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31
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Seifert JRK, Mlodzik M. Frizzled/PCP signalling: a conserved mechanism regulating cell polarity and directed motility. Nat Rev Genet 2007; 8:126-38. [PMID: 17230199 DOI: 10.1038/nrg2042] [Citation(s) in RCA: 377] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Signalling through Frizzled (Fz)/planar cell polarity (PCP) is a conserved mechanism that polarizes cells along specific axes in a tissue. Genetic screens in Drosophila melanogaster pioneered the discovery of core PCP factors, which regulate the orientation of hairs on wings and facets in eyes. Recent genetic evidence shows that the Fz/PCP pathway is conserved in vertebrates and is crucial for disparate processes as gastrulation and sensory cell orientation. Fz/PCP signalling depends on complex interactions between core components, leading to their asymmetric distribution and ultimately polarized activity in a cell. Whereas several mechanistic aspects of PCP have been uncovered, the global coordination of this polarization remains debated.
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Affiliation(s)
- Jessica R K Seifert
- Brookdale Department of Molecular, Cell and Developmental Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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32
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Tsruya R, Wojtalla A, Carmon S, Yogev S, Reich A, Bibi E, Merdes G, Schejter E, Shilo BZ. Rhomboid cleaves Star to regulate the levels of secreted Spitz. EMBO J 2007; 26:1211-20. [PMID: 17304216 PMCID: PMC1817629 DOI: 10.1038/sj.emboj.7601581] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 01/02/2007] [Indexed: 11/08/2022] Open
Abstract
Intracellular trafficking of the precursor of Spitz (Spi), the major Drosophila EGF receptor (EGFR) ligand, is facilitated by the chaperone Star, a type II transmembrane protein. This study identifies a novel mechanism for modulating the activity of Star, thereby influencing the levels of active Spi ligand produced. We demonstrate that Star can efficiently traffic Spi even when present at sub-stoichiometric levels, and that in Drosophila S(2)R(+) cells, Spi is trafficked from the endoplasmic reticulum to the late endosome compartment, also enriched for Rhomboid, an intramembrane protease. Rhomboid, which cleaves the Spi precursor, is now shown to also cleave Star within its transmembrane domain both in cell culture and in flies, expanding the repertoire of known Rhomboid substrates to include both type I and type II transmembrane proteins. Cleavage of Star restricts the amount of Spi that is trafficked, and may explain the exceptional dosage sensitivity of the Star locus in flies.
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Affiliation(s)
- Rachel Tsruya
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Shari Carmon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shaul Yogev
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Aderet Reich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Bibi
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Gunter Merdes
- ZMBH, INF282, Heidelberg, Germany
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Eyal Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel. Tel.: +972 8 9343169; Fax: +972 8 9344108; E-mail:
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33
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Doroquez DB, Rebay I. Signal integration during development: mechanisms of EGFR and Notch pathway function and cross-talk. Crit Rev Biochem Mol Biol 2007; 41:339-85. [PMID: 17092823 DOI: 10.1080/10409230600914344] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metazoan development relies on a highly regulated network of interactions between conserved signal transduction pathways to coordinate all aspects of cell fate specification, differentiation, and growth. In this review, we discuss the intricate interplay between the epidermal growth factor receptor (EGFR; Drosophila EGFR/DER) and the Notch signaling pathways as a paradigm for signal integration during development. First, we describe the current state of understanding of the molecular architecture of the EGFR and Notch signaling pathways that has resulted from synergistic studies in vertebrate, invertebrate, and cultured cell model systems. Then, focusing specifically on the Drosophila eye, we discuss how cooperative, sequential, and antagonistic relationships between these pathways mediate the spatially and temporally regulated processes that generate this sensory organ. The common themes underlying the coordination of the EGFR and Notch pathways appear to be broadly conserved and should, therefore, be directly applicable to elucidating mechanisms of information integration and signaling specificity in vertebrate systems.
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Affiliation(s)
- David B Doroquez
- Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, USA
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34
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Luo X, Puig O, Hyun J, Bohmann D, Jasper H. Foxo and Fos regulate the decision between cell death and survival in response to UV irradiation. EMBO J 2006; 26:380-90. [PMID: 17183370 PMCID: PMC1783446 DOI: 10.1038/sj.emboj.7601484] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 11/08/2006] [Indexed: 01/23/2023] Open
Abstract
Cells damaged by environmental insults have to be repaired or eliminated to ensure tissue homeostasis in metazoans. Recent studies suggest that the balance between cell survival signals and pro-apoptotic stimuli controls the decision between cell repair and death. How these competing signals are integrated and interpreted to achieve accurate control over cell fate in vivo is incompletely understood. Here, we show that the Forkhead Box O transcription factor Foxo and the AP-1 transcription factor DFos are required downstream of Jun-N-terminal kinase signaling for the apoptotic response to UV-induced DNA damage in the developing Drosophila retina. Both transcription factors regulate the pro-apoptotic gene hid. Our results indicate that UV-induced apoptosis is repressed by receptor tyrosine kinase-mediated inactivation of Foxo. These data suggest that integrating stress and survival signals through Foxo drives the decision between cell death and repair of damaged cells in vivo.
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Affiliation(s)
- Xi Luo
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Oscar Puig
- Institute of Biotechnology, University of Helsinki, Viikinkaari, Finland
| | - Joogyung Hyun
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA
| | - Dirk Bohmann
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA
| | - Heinrich Jasper
- Department of Biology, University of Rochester, Rochester, NY, USA
- Department of Biology, University of Rochester, River Campus Box 270211, Rochester, NY 14627, USA. Tel.: +1 585 275 8973; Fax: +1 585 275 2070; E-mail:
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35
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Brown KE, Baonza A, Freeman M. Epithelial cell adhesion in the developing Drosophila retina is regulated by Atonal and the EGF receptor pathway. Dev Biol 2006; 300:710-21. [PMID: 16963016 DOI: 10.1016/j.ydbio.2006.08.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 07/31/2006] [Accepted: 08/01/2006] [Indexed: 11/27/2022]
Abstract
In the Drosophila retina, photoreceptor differentiation is preceded by significant cell shape rearrangements within and immediately behind the morphogenetic furrow. Groups of cells become clustered into arcs and rosettes in the plane of the epithelium, from which the neurons subsequently emerge. These cell clusters also have differential adhesive properties: adherens junction components are upregulated relative to surrounding cells. Little is known about how these morphological changes are orchestrated and what their relevance is for subsequent neuronal differentiation. Here, we report that the transcription factor Atonal and the canonical EGF receptor signalling cascade are both required for this clustering and for the accompanying changes in cellular adhesion. In the absence of either component, no arcs are formed behind the furrow, and all cells show low Armadillo and DE-cadherin levels, although in the case of EGFR pathway mutants, single, presumptive R8 cells with high levels of adherens junction components can be seen. Atonal regulates DE-cadherin transcriptionally, whereas the EGFR pathway, acting through the transcription factor Pointed, exerts its effects on adherens junctions indirectly, at a post-transcriptional level. These observations define a new function for EGFR signalling in eye development and illustrate a mechanism for the control of epithelial morphology by developmental signals.
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Affiliation(s)
- Katherine E Brown
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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36
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Adherens junctions in Drosophila retinal morphogenesis. Trends Cell Biol 2006; 17:26-35. [PMID: 17134901 DOI: 10.1016/j.tcb.2006.11.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 10/06/2006] [Accepted: 11/16/2006] [Indexed: 12/25/2022]
Abstract
Adherens junctions and their core molecular components, classic cadherins, make major contributions to animal morphogenesis. Although the significance of cadherins in development is generally accepted, the mechanisms regulating adherens junction function during morphogenesis remain a subject of intense research. Adherens junctions are involved in the organization of simple cellular patterns, and more complex cell shape changes and cell movements that depend on the dynamic modulation of adherens junctions.
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37
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Mirkovic I, Mlodzik M. Cooperative activities of drosophila DE-cadherin and DN-cadherin regulate the cell motility process of ommatidial rotation. Development 2006; 133:3283-93. [PMID: 16887833 DOI: 10.1242/dev.02468] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ommatidial rotation is a cell motility read-out of planar cell polarity (PCP) signaling in the Drosophila eye. Although the signaling aspects of PCP establishment are beginning to be unraveled, the mechanistic aspects of the associated ommatidial rotation process remain unknown. Here, we demonstrate that the Drosophila DE- and DN-cadherins have opposing effects on rotation. DE-cadherin promotes rotation, as DE-cad mutant ommatidia rotate less than wild type or not at all. By contrast, the two DN-cadherins act to restrict this movement, with ommatidia rotating too fast in the mutants. The opposing effects of DE- and DN-cadherins result in a coordinated cellular movement, enabling ommatidia of the same stage to rotate simultaneously. Genetic interactions, phenotypic analysis and localization studies indicate that EGF-receptor and Frizzled-PCP signaling feed into the regulation of cadherin activity and localization in this context. Thus, DE- and DN-cadherins integrate inputs from at least two signaling pathways, resulting in a coordinated cell movement. A similar input into mammalian E- and N-cadherins might function in the progression of diseases such as metastatic ovarian cancer.
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Affiliation(s)
- Ivana Mirkovic
- Brookdale Department of Molecular, Cell and Developmental Biology, Mount Sinai School of Medicine, New York, NY, USA
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38
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Cela C, Llimargas M. Egfr is essential for maintaining epithelial integrity during tracheal remodelling in Drosophila. Development 2006; 133:3115-25. [PMID: 16831830 DOI: 10.1242/dev.02482] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A fundamental requirement during organogenesis is to preserve tissue integrity to render a mature and functional structure. Many epithelial organs, such as the branched tubular structures, undergo a tremendous process of tissue remodelling to attain their final pattern. The cohesive properties of these tissues need to be finely regulated to promote adhesion yet allow flexibility during extensive tissue remodelling. Here, we report a new role for the Egfr pathway in maintaining epithelial integrity during tracheal development in Drosophila. We show that the integrity-promoting Egfr function is transduced by the ERK-type MAPK pathway, but does not require the downstream transcription factor Pointed. Compromising Egfr signalling, by downregulating different elements of the pathway or by overexpressing the Mkp3 negative regulator, leads to loss of tube integrity, whereas upregulation of the pathway results in increased tissue stiffness. We find that regulation of MAPK pathway activity by Breathless signalling does not impinge on tissue integrity. Egfr effects on tissue integrity correlate with differences in the accumulation of markers for cadherin-based cell-cell adhesion. Accordingly, downregulation of cadherin-based cell-cell adhesion gives rise to tracheal integrity defects. Our results suggest that the Egfr pathway regulates maintenance of tissue integrity, at least in part, through the modulation of cell adhesion. This finding establishes a link between a developmental pathway governing tracheal formation and cell adhesiveness.
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Affiliation(s)
- Carolina Cela
- Institut de Biologia Molecular de Barcelona (IBMB Samitier 1-5, 08028 Barcelona, Spain
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39
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Vrailas AD, Marenda DR, Cook SE, Powers MA, Lorenzen JA, Perkins LA, Moses K. smoothened and thickveins regulate Moleskin/Importin 7-mediated MAP kinase signaling in the developing Drosophila eye. Development 2006; 133:1485-94. [PMID: 16540506 PMCID: PMC1994332 DOI: 10.1242/dev.02334] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila Mitogen Activated Protein Kinase (MAPK) Rolled is a key regulator of developmental signaling, relaying information from the cytoplasm into the nucleus. Cytoplasmic MEK phosphorylates MAPK (pMAPK), which then dimerizes and translocates to the nucleus where it regulates transcription factors. In cell culture, MAPK nuclear translocation directly follows phosphorylation, but in developing tissues pMAPK can be held in the cytoplasm for extended periods (hours). Here, we show that Moleskin antigen (Drosophila Importin 7/Msk), a MAPK transport factor, is sequestered apically at a time when lateral inhibition is required for patterning in the developing eye. We suggest that this apical restriction of Msk limits MAPK nuclear translocation and blocks Ras pathway nuclear signaling. Ectopic expression of Msk overcomes this block and disrupts patterning. Additionally, the MAPK cytoplasmic hold is genetically dependent on the presence of Decapentaplegic (Dpp) and Hedgehog receptors.
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Affiliation(s)
- Alysia D Vrailas
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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40
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Charroux B, Freeman M, Kerridge S, Baonza A. Atrophin contributes to the negative regulation of epidermal growth factor receptor signaling in Drosophila. Dev Biol 2006; 291:278-90. [PMID: 16445904 DOI: 10.1016/j.ydbio.2005.12.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 11/21/2005] [Accepted: 12/06/2005] [Indexed: 11/18/2022]
Abstract
Dentato-rubral and pallido-luysian atrophy (DRPLA) is a dominant, progressive neurodegenerative disease caused by the expansion of polyglutamine repeats within the human Atrophin-1 protein. Drosophila Atrophin and its human orthologue are thought to function as transcriptional co-repressors. Here, we report that Drosophila Atrophin participates in the negative regulation of Epidermal Growth Factor Receptor (EGFR) signaling both in the wing and the eye imaginal discs. In the wing pouch, Atrophin loss of function clones induces cell autonomous expression of the EGFR target gene Delta, and the formation of extra vein tissue, while overexpression of Atrophin inhibits EGFR-dependent vein formation. In the eye, Atrophin cooperates with other negative regulators of the EGFR signaling to prevent the differentiation of surplus photoreceptor cells and to repress Delta expression. Overexpression of Atrophin in the eye reduces the EGFR-dependent recruitment of cone cells. In both the eye and wing, epistasis tests show that Atrophin acts downstream or in parallel to the MAP kinase rolled to modulate EGFR signaling outputs. We show that Atrophin genetically cooperates with the nuclear repressor Yan to inhibit the EGFR signaling activity. Finally, we have found that expression of pathogenic or normal forms of human Atrophin-1 in the wing promotes wing vein differentiation and acts as dominant negative proteins inhibiting endogenous fly Atrophin activity.
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Affiliation(s)
- Bernard Charroux
- Laboratoire de Génétique et Physiologie du Développement, UMR 6545 CNRS-Université, IBDM-CNRS-Université de la Méditerranée, Marseille Cedex 09 13288, France
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41
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Firth LC, Li W, Zhang H, Baker NE. Analyses of RAS regulation of eye development in Drosophila melanogaster. Methods Enzymol 2006; 407:711-21. [PMID: 16757364 DOI: 10.1016/s0076-6879(05)07056-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Many aspects of Drosophila eye development depend on receptor tyrosine kinases that signal through Ras. Genetic studies and genetic screens using eye morphology and development as assays have identified major components of receptor tyrosine kinase and Ras signaling and outlined specific contributions of these components to cell fate specification and differentiation, cell survival, cell cycle progression and arrest, and cellular movements and morphology. This chapter presents a brief compendium of methods and strains that may be used to obtain overexpression or loss of function for Ras pathway genes in the eye and methods and reagents permitting initial characterization of retinal cell differentiation, death, and cell cycle behavior.
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Affiliation(s)
- Lucy C Firth
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, New York, USA
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42
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Rodrigues AB, Werner E, Moses K. Genetic and biochemical analysis of the role of Egfr in the morphogenetic furrow of the developing Drosophila eye. Development 2005; 132:4697-707. [PMID: 16207755 DOI: 10.1242/dev.02058] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A key event in patterning the developing Drosophila compound eye is the progressive restriction of the transcription factor Atonal in the morphogenetic furrow. The Atonal pattern evolves from expression in all cells to an over-dispersed pattern of single founder cells (the future R8 photoreceptors). This restriction involves Notch-mediated lateral inhibition. However, there have been inconsistent data on a similar proposed role for the Egf receptor (Egfr). Experiments using a conditional Egfr mutation (Egfr(tsla)) suggested that Egfr does not regulate Atonal restriction, whereas experiments using Egfr-null mosaic Minute+ clones suggested that it does. Here, we have re-examined both approaches. We report that the lesion in Egfr(tsla) is a serine to phenylalanine change in a conserved extracellular ligand-binding domain. We show by biochemical and genetic approaches that the Egfr(tsla) protein is rapidly and completely inactivated upon shift to the non-permissive temperature. We also find that on temperature shift the protein moves from the cell surface into the cell. Finally, we report a flaw in the Egfr-null mosaic Minute+ clone approach. Thus, we demonstrate that Egfr does not play a role in the initial specification or spacing of ommatidial founder cells.
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Affiliation(s)
- Aloma B Rodrigues
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322-3030, USA
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43
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Schlesinger A, Kiger A, Perrimon N, Shilo BZ. Small Wing PLCγ Is Required for ER Retention of Cleaved Spitz during Eye Development in Drosophila. Dev Cell 2004; 7:535-45. [PMID: 15469842 DOI: 10.1016/j.devcel.2004.09.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 08/11/2004] [Accepted: 08/12/2004] [Indexed: 11/25/2022]
Abstract
The Drosophila EGF receptor ligand Spitz is cleaved by Rhomboid to generate an active secreted molecule. Surprisingly, when a cleaved variant of Spitz (cSpi) was expressed, it accumulated in the ER, both in embryos and in cell culture. A cell-based RNAi screen for loss-of-function phenotypes that alleviate ER accumulation of cSpi identified several genes, including the small wing (sl) gene encoding a PLCgamma. sl mutants compromised ER accumulation of cSpi in embryos, yet they exhibit EGFR hyperactivation phenotypes predominantly in the eye. Spi processing in the eye is carried out primarily by Rhomboid-3/Roughoid, which cleaves Spi in the ER, en route to the Golgi. The sl mutant phenotype is consistent with decreased cSpi retention in the R8 cells. Retention of cSpi in the ER provides a novel mechanism for restricting active ligand levels and hence the range of EGFR activation in the developing eye.
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Affiliation(s)
- Ayelet Schlesinger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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44
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Zeng YA, Verheyen EM. Nemo is an inducible antagonist of Wingless signaling during Drosophila wing development. Development 2004; 131:2911-20. [PMID: 15169756 DOI: 10.1242/dev.01177] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cellular events that govern patterning during animal development must be precisely regulated. This is achieved by extrinsic factors and through the action of both positive and negative feedback loops. Wnt/Wg signals are crucial across species in many developmental patterning events. We report that Drosophila nemo (nmo) acts as an intracellular feedback inhibitor of Wingless (Wg) and that it is a novel Wg target gene. Nemo antagonizes the activity of the Wg signal, as evidenced by the finding that reduction of nmo rescues the phenotypic defects induced by misexpression of various Wg pathway components. In addition, the activation of Wg-dependent gene expression is suppressed in wing discs ectopically expressing nmo and enhanced cell autonomously in nmo mutant clones. We find that nmo itself is a target of Wg signaling in the imaginal wing disc. nmo expression is induced upon high levels of Wg signaling and can be inhibited by interfering with Wg signaling. Finally, we observe alterations in Arm stabilization upon modulation of Nemo. These observations suggest that the patterning mechanism governed by Wg involves a negative feedback circuit in which Wg induces expression of its own antagonist Nemo.
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Affiliation(s)
- Yi A Zeng
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
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45
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Abstract
Planar cell polarity (PCP) has been demonstrated in the epithelium of organisms from flies to humans. Recent research has revealed that the planar organization of cells requires a conserved set of genes, known as the PCP genes. Tbe PCP proteins Frizzled (Fz) and Dishevelled (Dsh) function as key players in PCP signalling. Although Fz and Dsh are also involved in Wingless (Wg)/Wnt signalling, these proteins have independent functions in a non-canonical pathway dedicated to PCP. Reorganization of the cell surface and cytoskeleton is required, and recent work has focused on how cell adhesion molecules (such as Fat, Dachsous and Flamingo) function in this process.
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Affiliation(s)
- Manolis Fanto
- Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK
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46
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Gaengel K, Mlodzik M. Egfr signaling regulates ommatidial rotation and cell motility in theDrosophilaeye via MAPK/Pnt signaling and the Ras effector Canoe/AF6. Development 2003; 130:5413-23. [PMID: 14507782 DOI: 10.1242/dev.00759] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epidermal Growth Factor-receptor (Egfr) signaling is evolutionarily conserved and controls a variety of different cellular processes. In Drosophila these include proliferation, patterning, cell-fate determination, migration and survival. Here we provide evidence for a new role of Egfr signaling in controlling ommatidial rotation during planar cell polarity (PCP) establishment in the Drosophila eye. Although the signaling pathways involved in PCP establishment and photoreceptor cell-type specification are beginning to be unraveled, very little is known about the associated 90° rotation process. One of the few rotation-specific mutations known is roulette (rlt) in which ommatidia rotate to a random degree, often more than 90°. Here we show that rlt is a rotation-specific allele of the inhibitory Egfr ligand Argos and that modulation of Egfr activity shows defects in ommatidial rotation. Our data indicate that, beside the Raf/MAPK cascade, the Ras effector Canoe/AF6 acts downstream of Egfr/Ras and provides a link from Egfr to cytoskeletal elements in this developmentally regulated cell motility process. We provide further evidence for an involvement of cadherins and non-muscle myosin II as downstream components controlling rotation. In particular, the involvement of the cadherin Flamingo, a PCP gene, downstream of Egfr signaling provides the first link between PCP establishment and the Egfr pathway.
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Affiliation(s)
- Konstantin Gaengel
- Mount Sinai School of Medicine, Brookdale Department of Molecular, Cell and Developmental Biology, 1 Gustave L. Levy Place, New York, NY 10029, USA
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