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Presser A, Freund O, Hassapelis T, Hunter G. Scabrous is distributed via signaling filopodia to modulate Notch response during bristle patterning in Drosophila. PLoS One 2023; 18:e0291409. [PMID: 37729137 PMCID: PMC10511103 DOI: 10.1371/journal.pone.0291409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/29/2023] [Indexed: 09/22/2023] Open
Abstract
During development, cells in tissues must be patterned correctly in order to support tissue function and shape. The sensory bristles of the peripheral nervous system on the thorax of Drosophila melanogaster self-organizes from a unpatterned epithelial tissue to a regular spot pattern during pupal stages. Wild type patterning requires Notch-mediated lateral inhibition. Scabrous is a protein that can bind to and modify Notch receptor activity. Scabrous can be secreted, but it is also known to be localized to basal signaling filopodia, or cytonemes, that play a role in long-range Notch signaling. Here we show that Scabrous is primarily distributed basally, within the range of signaling filopodia extension. We show that filamentous actin dynamics are required for the distribution of Scabrous protein during sensory bristle patterning stages. We show that the Notch response of epithelial cells is sensitive to the level of Scabrous protein being expressed by the sensory bristle precursor cell. Our findings at the cell-level suggest a model for how epithelial cells engaged in lateral inhibition at a distance are sensitive local levels of Scabrous protein.
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Affiliation(s)
- Adam Presser
- Department of Biology, Clarkson University, Potsdam, New York, United States of America
| | - Olivia Freund
- Department of Biology, Clarkson University, Potsdam, New York, United States of America
| | - Theodora Hassapelis
- Department of Biology, Clarkson University, Potsdam, New York, United States of America
| | - Ginger Hunter
- Department of Biology, Clarkson University, Potsdam, New York, United States of America
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2
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Koca Y, Vuong LT, Singh J, Giniger E, Mlodzik M. Notch-dependent Abl signaling regulates cell motility during ommatidial rotation in Drosophila. Cell Rep 2022; 41:111788. [PMID: 36476875 DOI: 10.1016/j.celrep.2022.111788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Lacoste J, Soula H, Burg A, Audibert A, Darnat P, Gho M, Louvet-Vallée S. A neural progenitor mitotic wave is required for asynchronous axon outgrowth and morphology. eLife 2022; 11:75746. [PMID: 35254258 PMCID: PMC8933001 DOI: 10.7554/elife.75746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/06/2022] [Indexed: 11/16/2022] Open
Abstract
Spatiotemporal mechanisms generating neural diversity are fundamental for understanding neural processes. Here, we investigated how neural diversity arises from neurons coming from identical progenitors. In the dorsal thorax of Drosophila, rows of mechanosensory organs originate from the division of sensory organ progenitor (SOPs). We show that in each row of the notum, an anteromedial located central SOP divides first, then neighbouring SOPs divide, and so on. This centrifugal wave of mitoses depends on cell-cell inhibitory interactions mediated by SOP cytoplasmic protrusions and Scabrous, a secreted protein interacting with the Delta/Notch complex. Furthermore, when this mitotic wave was reduced, axonal growth was more synchronous, axonal terminals had a complex branching pattern and fly behaviour was impaired. We show that the temporal order of progenitor divisions influences the birth order of sensory neurons, axon branching and impact on grooming behaviour. These data support the idea that developmental timing controls axon wiring neural diversity.
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Affiliation(s)
- Jérôme Lacoste
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
| | - Hédi Soula
- NutriOmics Research Unit, Sorbonne Université, INSERM, Paris, France
| | - Angélique Burg
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
| | - Agnès Audibert
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
| | - Pénélope Darnat
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
| | - Michel Gho
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
| | - Sophie Louvet-Vallée
- UMR 7622 laboratory of Developmental Biology, CNRS Sorbonne-Université, Paris, France
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4
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Gallagher KD, Mani M, Carthew RW. Emergence of a geometric pattern of cell fates from tissue-scale mechanics in the Drosophila eye. eLife 2022; 11:72806. [PMID: 35037852 PMCID: PMC8863370 DOI: 10.7554/elife.72806] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 01/15/2022] [Indexed: 12/02/2022] Open
Abstract
Pattern formation of biological structures involves the arrangement of different types of cells in an ordered spatial configuration. In this study, we investigate the mechanism of patterning the Drosophila eye epithelium into a precise triangular grid of photoreceptor clusters called ommatidia. Previous studies had led to a long-standing biochemical model whereby a reaction-diffusion process is templated by recently formed ommatidia to propagate a molecular prepattern across the eye. Here, we find that the templating mechanism is instead, mechanochemical in origin; newly born columns of differentiating ommatidia serve as a template to spatially pattern flows that move epithelial cells into position to form each new column of ommatidia. Cell flow is generated by a source and sink, corresponding to narrow zones of cell dilation and contraction respectively, that straddle the growing wavefront of ommatidia. The newly formed lattice grid of ommatidia cells are immobile, deflecting, and focusing the flow of other cells. Thus, the self-organization of a regular pattern of cell fates in an epithelium is mechanically driven.
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Affiliation(s)
- Kevin D Gallagher
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States,NSF Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
| | - Madhav Mani
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States,NSF Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States,Department of Engineering Sciences and Applied Mathematics, Northwestern UniversityEvanstonUnited States
| | - Richard W Carthew
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States,NSF Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
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5
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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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6
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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7
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Petruccelli E, Feyder M, Ledru N, Jaques Y, Anderson E, Kaun KR. Alcohol Activates Scabrous-Notch to Influence Associated Memories. Neuron 2018; 100:1209-1223.e4. [PMID: 30482693 DOI: 10.1016/j.neuron.2018.10.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/17/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
Drugs of abuse, like alcohol, modulate gene expression in reward circuits and consequently alter behavior. However, the in vivo cellular mechanisms through which alcohol induces lasting transcriptional changes are unclear. We show that Drosophila Notch/Su(H) signaling and the secreted fibrinogen-related protein Scabrous in mushroom body (MB) memory circuitry are important for the enduring preference of cues associated with alcohol's rewarding properties. Alcohol exposure affects Notch responsivity in the adult MB and alters Su(H) targeting at the dopamine-2-like receptor (Dop2R). Alcohol cue training also caused lasting changes to the MB nuclear transcriptome, including changes in the alternative splicing of Dop2R and newly implicated transcripts like Stat92E. Together, our data suggest that alcohol-induced activation of the highly conserved Notch pathway and accompanying transcriptional responses in memory circuitry contribute to addiction. Ultimately, this provides mechanistic insight into the etiology and pathophysiology of alcohol use disorder.
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Affiliation(s)
- Emily Petruccelli
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Michael Feyder
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Nicolas Ledru
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Yanabah Jaques
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Edward Anderson
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Karla R Kaun
- Department of Neuroscience, Brown University, Providence, RI 02912, USA.
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8
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Sarkar S, Khatun S, Dutta M, Roy S. Trans-generational transmission of altered phenotype resulting from flubendiamide-induced changes in apoptosis in larval imaginal discs of Drosophila melanogaster. Environ Toxicol Pharmacol 2017; 56:350-360. [PMID: 29121551 DOI: 10.1016/j.etap.2017.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/30/2017] [Accepted: 11/02/2017] [Indexed: 06/07/2023]
Abstract
The eye and wing morphology of Drosophila melanogaster maintain unique, stable pattern of genesis from larval eye and wing imaginal discs. Increased apoptosis in cells of eye and wing discs was found to be associated with flubendiamide (fluoride containing insecticide) exposure (at the range 0.25-10μg/mL) in D. melanogaster larvae. The chemical fed larvae on attaining adulthood revealed alterations in morphology and symmetry of their compound eyes and wings through scanning electron microscopy. Nearly 40% and 30% of flies (P generation) demonstrated alterations in eyes and wings respectively. Transmission electron microscopic study (at the range 1-20μg/mL) also established variation in the rhabdomere and pigment cell orientation as well as in the shape of the ommatidium. Subsequent SEM study with F1 and F2 generation flies also revealed structural variation in eye and wing. Decrease in percentage of altered eye and wing phenotype was noted in subsequent generations (P> F1>F2). Thus, the diamide insecticide, flubendiamide, expected to be environmentally safe at sub-lethal concentrations was found to increase apoptosis in larvae and thereby cause morphological alteration in the adult D. melanogaster. This study further demonstrated trans-generational transmission of altered phenotype in three subsequent generations of a non-target insect model, D. melanogaster.
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Affiliation(s)
- Saurabh Sarkar
- Toxicology Research Unit, Cytogenetics Laboratory, Department of Zoology, The University of Burdwan, Burdwan, West Bengal, 713104, India
| | - Salma Khatun
- Toxicology Research Unit, Cytogenetics Laboratory, Department of Zoology, The University of Burdwan, Burdwan, West Bengal, 713104, India
| | - Moumita Dutta
- Toxicology Research Unit, Cytogenetics Laboratory, Department of Zoology, The University of Burdwan, Burdwan, West Bengal, 713104, India
| | - Sumedha Roy
- Toxicology Research Unit, Cytogenetics Laboratory, Department of Zoology, The University of Burdwan, Burdwan, West Bengal, 713104, India.
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9
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Gavish A, Barkai N. A two-step patterning process increases the robustness of periodic patterning in the fly eye. J Biol Phys 2016; 42:317-38. [PMID: 26884095 DOI: 10.1007/s10867-016-9409-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 01/06/2016] [Indexed: 12/31/2022] Open
Abstract
Complex periodic patterns can self-organize through dynamic interactions between diffusible activators and inhibitors. In the biological context, self-organized patterning is challenged by spatial heterogeneities ('noise') inherent to biological systems. How spatial variability impacts the periodic patterning mechanism and how it can be buffered to ensure precise patterning is not well understood. We examine the effect of spatial heterogeneity on the periodic patterning of the fruit fly eye, an organ composed of ∼800 miniature eye units (ommatidia) whose periodic arrangement along a hexagonal lattice self-organizes during early stages of fly development. The patterning follows a two-step process, with an initial formation of evenly spaced clusters of ∼10 cells followed by a subsequent refinement of each cluster into a single selected cell. Using a probabilistic approach, we calculate the rate of patterning errors resulting from spatial heterogeneities in cell size, position and biosynthetic capacity. Notably, error rates were largely independent of the desired cluster size but followed the distributions of signaling speeds. Pre-formation of large clusters therefore greatly increases the reproducibility of the overall periodic arrangement, suggesting that the two-stage patterning process functions to guard the pattern against errors caused by spatial heterogeneities. Our results emphasize the constraints imposed on self-organized patterning mechanisms by the need to buffer stochastic effects. Author summary Complex periodic patterns are common in nature and are observed in physical, chemical and biological systems. Understanding how these patterns are generated in a precise manner is a key challenge. Biological patterns are especially intriguing, as they are generated in a noisy environment; cell position and cell size, for example, are subject to stochastic variations, as are the strengths of the chemical signals mediating cell-to-cell communication. The need to generate a precise and robust pattern in this 'noisy' environment restricts the space of patterning mechanisms that can function in the biological setting. Mathematical modeling is useful in comparing the sensitivity of different mechanisms to such variations, thereby highlighting key aspects of their design.We use mathematical modeling to study the periodic patterning of the fruit fly eye. In this system, a highly ordered lattice of differentiated cells is generated in a two-dimensional cell epithelium. The pattern is first observed by the appearance of evenly spaced clusters of ∼10 cells that express specific genes. Each cluster is subsequently refined into a single cell, which initiates the formation and differentiation of a miniature eye unit, the ommatidium. We formulate a mathematical model based on the known molecular properties of the patterning mechanism, and use a probabilistic approach to calculate the errors in cluster formation and refinement resulting from stochastic cell-to-cell variations ('noise') in different quantitative parameters. This enables us to define the parameters most influencing noise sensitivity. Notably, we find that this error is roughly independent of the desired cluster size, suggesting that large clusters are beneficial for ensuring the overall reproducibility of the periodic cluster arrangement. For the stage of cluster refinement, we find that rapid communication between cells is critical for reducing error. Our work provides new insights into the constraints imposed on mechanisms generating periodic patterning in a realistic, noisy environment, and in particular, discusses the different considerations in achieving optimal design of the patterning network.
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Affiliation(s)
- Avishai Gavish
- Department of Molecular Genetics, Weizmann institute of Science, Rehovot, 76100, Israel.
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann institute of Science, Rehovot, 76100, Israel
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10
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Abstract
Development creates a vast array of forms and patterns with elegant economy, using a small vocabulary of pattern-generating proteins such as BMPs, FGFs and Hh in similar ways in many different contexts. Despite much theoretical and experimental work, the signaling mechanisms that disperse these morphogen signaling proteins remain controversial. Here, we review the conceptual background and evidence that establishes a fundamental and essential role for cytonemes as specialized filopodia that transport signaling proteins between signaling cells. This evidence suggests that cytoneme-mediated signaling is a dispersal mechanism that delivers signaling proteins directly at sites of cell-cell contact.
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Affiliation(s)
- Thomas B. Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, CA 94156, USA
| | - Sougata Roy
- Cardiovascular Research Institute, University of California, San Francisco, CA 94156, USA
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12
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Charng WL, Yamamoto S, Jaiswal M, Bayat V, Xiong B, Zhang K, Sandoval H, David G, Gibbs S, Lu HC, Chen K, Giagtzoglou N, Bellen HJ. Drosophila Tempura, a novel protein prenyltransferase α subunit, regulates notch signaling via Rab1 and Rab11. PLoS Biol 2014; 12:e1001777. [PMID: 24492843 PMCID: PMC3904817 DOI: 10.1371/journal.pbio.1001777] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 12/16/2013] [Indexed: 11/23/2022] Open
Abstract
A forward genetic screen in Drosophila looking for Notch signaling regulators identifies Tempura, a new and non-redundant protein prenyltransferase of Rab proteins. Vesicular trafficking plays a key role in tuning the activity of Notch signaling. Here, we describe a novel and conserved Rab geranylgeranyltransferase (RabGGT)-α–like subunit that is required for Notch signaling-mediated lateral inhibition and cell fate determination of external sensory organs. This protein is encoded by tempura, and its loss affects the secretion of Scabrous and Delta, two proteins required for proper Notch signaling. We show that Tempura forms a heretofore uncharacterized RabGGT complex that geranylgeranylates Rab1 and Rab11. This geranylgeranylation is required for their proper subcellular localization. A partial dysfunction of Rab1 affects Scabrous and Delta in the secretory pathway. In addition, a partial loss Rab11 affects trafficking of Delta. In summary, Tempura functions as a new geranylgeranyltransferase that regulates the subcellular localization of Rab1 and Rab11, which in turn regulate trafficking of Scabrous and Delta, thereby affecting Notch signaling. Notch signaling is an evolutionarily conserved signaling pathway that regulates many developmental processes. Abnormal Notch signaling activity can lead to numerous diseases and developmental defects. To better understand the regulation of this pathway, we performed a forward genetic screen for Notch signaling components that have not been previously identified in Drosophila. Here, we report the identification of an evolutionarily conserved protein, Tempura, which is required for Notch signaling-mediated lateral inhibition and cell fate determination of external sensory organs. We show that loss of tempura leads to mistrafficking of Delta and Scabrous, two important Notch signaling components. In addition, Rab1 and Rab11, two major coordinators of vesicular trafficking, are mislocalizaed in tempura mutants. We further show that Tempura functions as a subunit of a previously uncharacterized lipid modification complex to geranylgeranylate (a type of prenylation) Rab1 and Rab11. This post-translational modification is shown to be required for the proper subcellular localization and function of these Rabs. We find that dysfunction of Rab1 causes an accumulation of Delta and Scabrous in the secretory pathway and dysfunction of Rab11 further interferes with the trafficking of Delta. In addition to the known Rab geranylgeranyltransferse, our data indicate the presence of another functionally nonredundant Rab geranylgeranyltransferse, Tempura.
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Affiliation(s)
- Wu-Lin Charng
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children′s Hospital, Houston, Texas, United States of America
| | - Manish Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Vafa Bayat
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Bo Xiong
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ke Zhang
- Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hector Sandoval
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Gabriela David
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Stephen Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hsiang-Chih Lu
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kuchuan Chen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Nikos Giagtzoglou
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neurology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children′s Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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13
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Danilchik M, Williams M, Brown E. Blastocoel-spanning filopodia in cleavage-stage Xenopus laevis: Potential roles in morphogen distribution and detection. Dev Biol 2013; 382:70-81. [PMID: 23916849 DOI: 10.1016/j.ydbio.2013.07.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 07/23/2013] [Accepted: 07/26/2013] [Indexed: 12/11/2022]
Abstract
In the frog Xenopus laevis, dorsal-ventral axis specification involves cytoskeleton-dependent transport of localized transcripts and proteins during the first cell cycle, and activation of the canonical Wnt pathway to locally stabilize translated beta-catenin which, by as early as the 32-cell stage, commits nuclei in prospective dorsal lineages to the subsequent expression of dorsal target genes. Maternal ligands important for activating this dorsal-specific signaling pathway are thought to interact with secreted glypicans and coreceptors in the blastocoel. While diffusion between cells is generally thought of as sufficient to accomplish the distribution of secreted maternal ligands to their appropriate targets, signaling may also involve other potential mechanisms, including direct transfer of morphogens via membrane-bounded entities, such as argosomes, exosomes, or even filopodia. In Xenopus, the blastocoel-facing, basolateral surfaces where signaling interactions ostensibly take place have not been previously examined in detail. Here, we report that the cleavage-stage blastocoel is traversed by hundreds of extremely long cellular protrusions that maintain long-term contacts between nonadjacent blastomeres during expansion of the interstitial space in early embryogenesis. The involvement of these protrusions in early embryonic patterning is suggested by the discoveries that (a) they fragment into microvesicles, whose resorption facilitates considerable exchange of cytoplasm and membrane between blastomeres; and (b) they are active in caveolar endocytosis, a prerequisite for ligand-receptor signaling.
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Affiliation(s)
- Michael Danilchik
- Department of Integrative Biosciences, SD-IB, Oregon Health & Sciences University, Portland, OR 97239-3097 USA.
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14
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Abstract
Notch signaling is an evolutionarily conserved pathway that plays a central role in numerous developmental and disease processes. The versatility of the Notch pathway relies on the activity of context-dependent regulators. These include rab11, sec15, arp3 and Drosophila EHBP1 (dEHBP1), which control Notch signaling and cell fate acquisition in asymmetrically dividing mechanosensory lineages by regulating the trafficking of the ligand Delta. Here, we show that dEHBP1 also controls the specification of R8 photoreceptors, as its loss results in the emergence of supernumerary R8 photoreceptors. Given the requirements for Notch signaling during lateral inhibition, we propose that dEHBP1 regulates distinct aspects of Notch signaling in different developmental contexts. We show that dEHBP1 regulates the exocytosis of Scabrous, a positive regulator of Notch signaling. In conclusion, dEHBP1 provides developmental versatility of intercellular signaling by regulating the trafficking of distinct Notch signaling components.
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Affiliation(s)
- Nikolaos Giagtzoglou
- Department of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
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15
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Mirkovic I, Gault WJ, Rahnama M, Jenny A, Gaengel K, Bessette D, Gottardi CJ, Verheyen EM, Mlodzik M. 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 DOI: 10.1038/nsmb.2049] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [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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17
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Wu JT, Lin WH, Chen WY, Huang YC, Tang CY, Ho MS, Pi H, Chien CT. CSN-mediated deneddylation differentially modulates Ci(155) proteolysis to promote Hedgehog signalling responses. Nat Commun 2011; 2:182. [PMID: 21304511 PMCID: PMC3105314 DOI: 10.1038/ncomms1185] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 01/11/2011] [Indexed: 01/15/2023] Open
Abstract
The Hedgehog (Hh) morphogen directs distinct cell responses according to its distinct signalling levels. Hh signalling stabilizes transcription factor cubitus interruptus (Ci) by prohibiting SCFSlimb-dependent ubiquitylation and proteolysis of Ci. How graded Hh signalling confers differential SCFSlimb-mediated Ci proteolysis in responding cells remains unclear. Here, we show that in COP9 signalosome (CSN) mutants, in which deneddylation of SCFSlimb is inactivated, Ci is destabilized in low-to-intermediate Hh signalling cells. As a consequence, expression of the low-threshold Hh target gene dpp is disrupted, highlighting the critical role of CSN deneddylation on low-to-intermediate Hh signalling response. The status of Ci phosphorylation and the level of E1 ubiquitin-activating enzyme are tightly coupled to this CSN regulation. We propose that the affinity of substrate–E3 interaction, ligase activity and E1 activity are three major determinants for substrate ubiquitylation and thereby substrate degradation in vivo. Hedgehog signalling gradients are required for proper wing formation in Drosophila, and Hedgehog is known to regulate the cubitus interruptus transcription factor. Here, the authors show that the COP9 signalosome has a critical role in translating a Hedgehog gradient into a cubitus interruptus gradient.
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Affiliation(s)
- June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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18
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Hanington PC, Zhang SM. The primary role of fibrinogen-related proteins in invertebrates is defense, not coagulation. J Innate Immun 2010; 3:17-27. [PMID: 21063081 DOI: 10.1159/000321882] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/08/2010] [Indexed: 12/15/2022] Open
Abstract
In vertebrates, the conversion of fibrinogen into fibrin is an essential process that underlies the establishment of the supporting protein framework required for coagulation. In invertebrates, fibrinogen-domain-containing proteins play a role in the defense response generated against pathogens; however, they do not function in coagulation, suggesting that this role has been recently acquired. Molecules containing fibrinogen motifs have been identified in numerous invertebrate organisms, and most of these molecules known to date have been linked to defense. Moreover, recent genome projects of invertebrate animals have revealed surprisingly high numbers of fibrinogen-like loci in their genomes, suggesting important and perhaps diverse functions of fibrinogen-like proteins in invertebrates. The ancestral role of molecules containing fibrinogen-related domains (FReDs) with immunity is the focus of this review, with emphasis on specific FReDs called fibrinogen-related proteins (FREPs) identified from the schistosome-transmitting mollusc Biomphalaria glabrata. Herein, we outline the range of invertebrate organisms FREPs can be found in, and detail the roles these molecules play in defense and protection against infection.
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Affiliation(s)
- Patrick C Hanington
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
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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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20
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Yamada S, Hotta K, Yamamoto TS, Ueno N, Satoh N, Takahashi H. Interaction of notochord-derived fibrinogen-like protein with Notch regulates the patterning of the central nervous system of Ciona intestinalis embryos. Dev Biol 2009; 328:1-12. [PMID: 19171129 DOI: 10.1016/j.ydbio.2008.12.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 12/04/2008] [Accepted: 12/22/2008] [Indexed: 10/21/2022]
Abstract
The midline organ the notochord and its overlying dorsal neural tube are the most prominent features of the chordate body plan. Although the molecular mechanisms involved in the formation of the central nervous system (CNS) have been studied extensively in vertebrate embryos, none of the genes that are expressed exclusively in notochord cells has been shown to function in this process. Here, we report a gene in the urochordate Ciona intestinalis encoding a fibrinogen-like protein that plays a pivotal role in the notochord-dependent positioning of neuronal cells. While this gene (Ci-fibrn) is expressed exclusively in notochord cells, its protein product is not confined to these cells but is distributed underneath the CNS as fibril-like protrusions. We demonstrated that Ci-fibrn interacts physically and functionally with Ci-Notch that is expressed in the central nervous system, and that the correct distribution of Ci-fibrn protein is dependent on Notch signaling. Disturbance of the Ci-fibrn distribution caused an abnormal positioning of neuronal cells and an abnormal track of axon extension. Therefore, it is highly likely that the interaction between the notochord-based fibrinogen-like protein and the neural tube-based Notch signaling plays an essential role in the proper patterning of CNS.
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Affiliation(s)
- Shigehiro Yamada
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
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21
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Abstract
The Drosophila eye is one of nature's most beautiful structures and one of its most useful. It has emerged as a favored model for understanding the processes that direct cell fate specification, patterning, and morphogenesis. Though composed of thousands of cells, each fly eye is a simple repeating pattern of perhaps a dozen cell types arranged in a hexagonal array that optimizes coverage of the visual field. This simple structure combined with powerful genetic tools make the fly eye an ideal model to explore the relationships between local cell fate specification and global tissue patterning. In this chapter, I discuss the basic principles that have emerged from three decades of close study. We now understand at a useful level some of the basic principles of cell fate selection and the importance of local cell-cell communication. We understand less of the processes by which signaling combines with morphogenesis and basic cell biology to create a correctly patterned neuroepithelium. Progress is being made on these fundamental issues, and in this chapter I discuss some of the principles that are beginning to emerge.
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Affiliation(s)
- Ross Cagan
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY, USA
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Abstract
The Notch signaling pathway regulates a diverse array of cell types and cellular processes and is tightly regulated by ligand binding. Both canonical and noncanonical Notch ligands have been identified that may account for some of the pleiotropic nature associated with Notch signaling. This review focuses on the molecular mechanisms by which Notch ligands function as signaling agonists and antagonists, and discusses different modes of activating ligands as well as findings that support intrinsic ligand signaling activity independent of Notch. Post-translational modification, proteolytic processing, endocytosis and membrane trafficking, as well as interactions with the actin cytoskeleton may contribute to the recently appreciated multifunctionality of Notch ligands. The regulation of Notch ligand expression by other signaling pathways provides a mechanism to coordinate Notch signaling with multiple cellular and developmental cues. The association of Notch ligands with inherited human disorders and cancer highlights the importance of understanding the molecular nature and activities intrinsic to Notch ligands. Oncogene (2008) 27, 5148-5167; doi:10.1038/onc.2008.229.
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Affiliation(s)
- B D'Souza
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1737, USA
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23
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Abstract
The ability of cells to receive, process, and respond to information is essential for a variety of biological processes. This is true for the simplest single cell entity as it is for the highly specialized cells of multicellular organisms. In the latter, most cells do not exist as independent units, but are organized into specialized tissues. Within these functional assemblies, cells communicate with each other in different ways to coordinate physiological processes. Recently, a new type of cell-to-cell communication was discovered, based on de novo formation of membranous nanotubes between cells. These F-actin-rich structures, referred to as tunneling nanotubes (TNT), were shown to mediate membrane continuity between connected cells and facilitate the intercellular transport of various cellular components. The subsequent identification of TNT-like structures in numerous cell types revealed some structural diversity. At the same time it emerged that the direct transfer of cargo between cells is a common functional property, suggesting a general role of TNT-like structures in selective, long-range cell-to-cell communication. Due to the growing number of documented thin and long cell protrusions in tissue implicated in cell-to-cell signaling, it is intriguing to speculate that TNT-like structures also exist in vivo and participate in important physiological processes.
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Affiliation(s)
- Steffen Gurke
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
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24
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Abstract
Communication among cells by means of the exchange of signaling cues is important for tissue and organ development. Recent reports indicate that one way that signaling cues can be delivered is by movement along cellular protrusions interconnecting cells. Here, by using confocal laser scanning microscopy and three-dimensional rendering, we describe in Drosophila melanogaster wing imaginal discs lateral protrusions interconnecting cells of the columnar epithelium. Moreover, we identified protrusions of the apical surface of columnar cells that reached and apparently contacted cells of the overlying squamous epithelium. Both apical and lateral protrusions could be visualized by expression of Tkv-GFP, a green fluorescent protein (GFP) -tagged version of a receptor of the Dpp/BMP4 signaling molecule, and the endosome marker GFP-Rab5. Our results demonstrate a previously unexpected richness of cellular protrusions within wing imaginal discs and support the view that cellular protrusions may provide a means for exchanging signaling cues between cells.
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Affiliation(s)
- Fabio Demontis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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25
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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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26
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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27
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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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28
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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29
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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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30
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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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31
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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32
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Vrailas AD, Moses K. Smoothened, thickveins and the genetic control of cell cycle and cell fate in the developing Drosophila eye. Mech Dev 2006; 123:151-65. [PMID: 16412615 DOI: 10.1016/j.mod.2005.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 11/04/2005] [Accepted: 11/07/2005] [Indexed: 11/18/2022]
Abstract
The Hedgehog and Decapentaplegic pathways have several well-characterized functions in the developing Drosophila compound eye, including initiation and progression of the morphogenetic furrow. Other functions involve control of cell cycle and cell survival as well as cell type specification. Here we have used the mosaic clone analysis of null mutations of the smoothened and thickveins genes (which encode the receptors for these two signals) both alone and in combination, to study cell cycle and cell fate in the developing eye. We conclude that both pathways have several, but differing roles in furrow induction and cell fate and survival, but that neither directly affects cell type specification.
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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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Hsiung F, Ramirez-Weber FA, Iwaki DD, Kornberg TB. Dependence of Drosophila wing imaginal disc cytonemes on Decapentaplegic. Nature 2005; 437:560-3. [PMID: 16177792 DOI: 10.1038/nature03951] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 06/16/2005] [Indexed: 11/09/2022]
Abstract
The anterior/posterior (A/P) and dorsal/ventral (D/V) compartment borders that subdivide the wing imaginal discs of Drosophila third instar larvae are each associated with a developmental organizer. Decapentaplegic (Dpp), a member of the transforming growth factor-beta (TGF-beta) superfamily, embodies the activity of the A/P organizer. It is produced at the A/P organizer and distributes in a gradient of decreasing concentration to regulate target genes, functioning non-autonomously to regulate growth and patterning of both the anterior and posterior compartments. Wingless (Wg) is produced at the D/V organizer and embodies its activity. The mechanisms that distribute Dpp and Wg are not known, but proposed mechanisms include extracellular diffusion, successive transfers between neighbouring cells, vesicle-mediated movement, and direct transfer via cytonemes. Cytonemes are actin-based filopodial extensions that have been found to orient towards the A/P organizer from outlying cells. Here we show that in the wing disc, cytonemes orient towards both the A/P and D/V organizers, and that their presence and orientation correlates with Dpp signalling. We also show that the Dpp receptor, Thickveins (Tkv), is present in punctae that move along cytonemes. These observations are consistent with a role for cytonemes in signal transduction.
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Affiliation(s)
- Frank Hsiung
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
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Abstract
Tiny protrusions on the surface of cells might be a more common mechanism for cell communication than previously expected
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Affiliation(s)
- Fabio Demontis
- International Max Planck Research School working with Christian Dahmann at the Max Planck Institute for Cell Biology and Genetics in Dresden, Germany.
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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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
The coordinated polarization of cells within an epithelium is required for the development and function of some tissues. Recent work has shown that the EGF receptor signaling pathway plays a key role in establishing epithelial polarity in the compound eye of Drosophila.
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Affiliation(s)
- Tanya Wolff
- Washington University School of Medicine, Department of Genetics, Box 8232, St. Louis, Missouri 63110, USA
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Abstract
Ommatidial rotation in the Drosophila eye provides a striking example of the precision with which tissue patterning can be achieved. Ommatidia in the adult eye are aligned at right angles to the equator, with dorsal and ventral ommatidia pointing in opposite directions. This pattern is established during disc development, when clusters rotate through 90 degrees, a process dependent on planar cell polarity and rotation-specific factors such as Nemo and Scabrous. Here, we demonstrate a requirement for epidermal growth factor receptor (Egfr) signalling in rotation, further adding to the manifold actions of this pathway in eye development. Egfr is distinct from other rotation factors in that the initial process is unaffected, but orientation in the adult is greatly disrupted when signalling is abnormal. We propose that Egfr signalling acts in the third instar imaginal disc to 'lock' ommatidia in their final position, and that in its absence, ommatidial orientation becomes disrupted during the remodelling of the larval disc into an adult eye. This lock may be achieved by a change in the adhesive properties of the cells: cadherin-based adhesion is important for ommatidia to remain in their appropriate positions. In addition, we have evidence that there is an error-correction mechanism operating during pupal stages to reposition inappropriately orientated ommatidia. Our results suggest that initial patterning events are not sufficient to achieve the precise architecture of the fly eye, and highlight a novel requirement for error-correction, and for an Egfr-dependent protection function to prevent morphological disruption during tissue remodelling.
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Affiliation(s)
- Katherine E Brown
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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Abstract
Notch and Delta are required for lateral inhibition during eye development. They prevent a tenfold excess in R8 photoreceptor cell specification. Mutations in two other genes, Scabrous and Gp150, result in more modestly increased R8 specification. Their roles in Notch signaling have been unclear. Both sca and gp150 are required for ectopic Notch activity that occurs in the split mutant. Similar phenotypes showed that sca and gp150 genes act in a common pathway. Gp150 was required for all activities of Sca, including inhibition of Notch activity and association with Notch-expressing cells that occur when Sca is ectopically expressed. Mosaic analysis found that the gp150 and sca genes were required in different cells from one another. Gp150 concentrated Sca protein in late endosomes. A model is proposed in which endosomal Sca and Gp150 promote Notch activation in response to Delta, by regulating acquisition of insensitivity to Delta in a subset of cells.
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Affiliation(s)
- Yanxia Li
- Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Abstract
Neurons make networks of intercellular connections. Many other cells also send out long cellular extensions and "touch" other cells far away. The extensions are intriguing, but what do they do? Possible rationales for this cell behavior include: (1) forming precise binary connections with the possibility of forming more complex networks, and (2) coupling of signaling with physical force.
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Affiliation(s)
- Pernille Rørth
- Developmental Biology Programme, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117, Heidelberg, Germany.
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