1
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Lago-Baldaia I, Cooper M, Seroka A, Trivedi C, Powell GT, Wilson SW, Ackerman SD, Fernandes VM. A Drosophila glial cell atlas reveals a mismatch between transcriptional and morphological diversity. PLoS Biol 2023; 21:e3002328. [PMID: 37862379 PMCID: PMC10619882 DOI: 10.1371/journal.pbio.3002328] [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: 08/13/2023] [Revised: 11/01/2023] [Accepted: 09/08/2023] [Indexed: 10/22/2023] Open
Abstract
Morphology is a defining feature of neuronal identity. Like neurons, glia display diverse morphologies, both across and within glial classes, but are also known to be morphologically plastic. Here, we explored the relationship between glial morphology and transcriptional signature using the Drosophila central nervous system (CNS), where glia are categorised into 5 main classes (outer and inner surface glia, cortex glia, ensheathing glia, and astrocytes), which show within-class morphological diversity. We analysed and validated single-cell RNA sequencing data of Drosophila glia in 2 well-characterised tissues from distinct developmental stages, containing distinct circuit types: the embryonic ventral nerve cord (VNC) (motor) and the adult optic lobes (sensory). Our analysis identified a new morphologically and transcriptionally distinct surface glial population in the VNC. However, many glial morphological categories could not be distinguished transcriptionally, and indeed, embryonic and adult astrocytes were transcriptionally analogous despite differences in developmental stage and circuit type. While we did detect extensive within-class transcriptomic diversity for optic lobe glia, this could be explained entirely by glial residence in the most superficial neuropil (lamina) and an associated enrichment for immune-related gene expression. In summary, we generated a single-cell transcriptomic atlas of glia in Drosophila, and our extensive in vivo validation revealed that glia exhibit more diversity at the morphological level than was detectable at the transcriptional level. This atlas will serve as a resource for the community to probe glial diversity and function.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Maia Cooper
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Austin Seroka
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Chintan Trivedi
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Gareth T. Powell
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Stephen W. Wilson
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Department of Pathology and Immunology, Brain Immunology and Glia Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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2
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Kozlov EN, Tokmatcheva EV, Khrustaleva AM, Grebenshchikov ES, Deev RV, Gilmutdinov RA, Lebedeva LA, Zhukova M, Savvateeva-Popova EV, Schedl P, Shidlovskii YV. Long-Term Memory Formation in Drosophila Depends on the 3'UTR of CPEB Gene orb2. Cells 2023; 12:cells12020318. [PMID: 36672258 PMCID: PMC9856895 DOI: 10.3390/cells12020318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/30/2022] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
Activation of local translation in neurites in response to stimulation is an important step in the formation of long-term memory (LTM). CPEB proteins are a family of translation factors involved in LTM formation. The Drosophila CPEB protein Orb2 plays an important role in the development and function of the nervous system. Mutations of the coding region of the orb2 gene have previously been shown to impair LTM formation. We found that a deletion of the 3'UTR of the orb2 gene similarly results in loss of LTM in Drosophila. As a result of the deletion, the content of the Orb2 protein remained the same in the neuron soma, but significantly decreased in synapses. Using RNA immunoprecipitation followed by high-throughput sequencing, we detected more than 6000 potential Orb2 mRNA targets expressed in the Drosophila brain. Importantly, deletion of the 3'UTR of orb2 mRNA also affected the localization of the Csp, Pyd, and Eya proteins, which are encoded by putative mRNA targets of Orb2. Therefore, the 3'UTR of the orb2 mRNA is important for the proper localization of Orb2 and other proteins in synapses of neurons and the brain as a whole, providing a molecular basis for LTM formation.
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Affiliation(s)
- Eugene N. Kozlov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Elena V. Tokmatcheva
- Institute of Physiology, Russian Academy of Sciences, 188680 St. Petersburg, Russia
| | - Anastasia M. Khrustaleva
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Eugene S. Grebenshchikov
- Department of Biology and General Genetics, Sechenov First Moscow State Medical University (Sechenov University), 119992 Moscow, Russia
| | - Roman V. Deev
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Rudolf A. Gilmutdinov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Lyubov A. Lebedeva
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Mariya Zhukova
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | | | - Paul Schedl
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Department of Molecular Biology, Princeton University, Princeton University, Princeton, NJ 08544-1014, USA
| | - Yulii V. Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Department of Biology and General Genetics, Sechenov First Moscow State Medical University (Sechenov University), 119992 Moscow, Russia
- Correspondence:
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3
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Wang YW, Wreden CC, Levy M, Meng JL, Marshall ZD, MacLean J, Heckscher E. Sequential addition of neuronal stem cell temporal cohorts generates a feed-forward circuit in the Drosophila larval nerve cord. eLife 2022; 11:79276. [PMID: 35723253 PMCID: PMC9333992 DOI: 10.7554/elife.79276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
How circuits self-assemble starting from neuronal stem cells is a fundamental question in developmental neurobiology. Here, we addressed how neurons from different stem cell lineages wire with each other to form a specific circuit motif. In Drosophila larvae, we combined developmental genetics (twin-spot mosaic analysis with a repressible cell marker, multi-color flip out, permanent labeling) with circuit analysis (calcium imaging, connectomics, network science). For many lineages, neuronal progeny are organized into subunits called temporal cohorts. Temporal cohorts are subsets of neurons born within a tight time window that have shared circuit-level function. We find sharp transitions in patterns of input connectivity at temporal cohort boundaries. In addition, we identify a feed-forward circuit that encodes the onset of vibration stimuli. This feed-forward circuit is assembled by preferential connectivity between temporal cohorts from different lineages. Connectivity does not follow the often-cited early-to-early, late-to-late model. Instead, the circuit is formed by sequential addition of temporal cohorts from different lineages, with circuit output neurons born before circuit input neurons. Further, we generate new tools for the fly community. Our data raise the possibility that sequential addition of neurons (with outputs oldest and inputs youngest) could be one fundamental strategy for assembling feed-forward circuits.
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Affiliation(s)
- Yi-wen Wang
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Chris C Wreden
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Maayan Levy
- Committee on Computational Neuroscience, University of ChicagoChicagoUnited States
| | - Julia L Meng
- Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States
| | - Zarion D Marshall
- Committee on Neurobiology, University of ChicagoChicagoUnited States
| | - Jason MacLean
- Committee on Computational Neuroscience, University of ChicagoChicagoUnited States,Committee on Neurobiology, University of ChicagoChicagoUnited States,Department of Neurobiology, University of ChicagoChicagoUnited States,University of Chicago Neuroscience InstituteChicagoUnited States
| | - Ellie Heckscher
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States,Committee on Computational Neuroscience, University of ChicagoChicagoUnited States,Program in Cell and Molecular Biology, University of ChicagoChicagoUnited States,Department of Neurobiology, University of ChicagoChicagoUnited States,University of Chicago Neuroscience InstituteChicagoUnited States
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4
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Kellermeyer R, Heydman LM, Gillis T, Mastick GS, Song M, Kidd T. Proteolytic cleavage of Slit by the Tolkin protease converts an axon repulsion cue to an axon growth cue in vivo. Development 2020; 147:dev.196055. [PMID: 32994163 PMCID: PMC7648596 DOI: 10.1242/dev.196055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022]
Abstract
Slit is a secreted protein that has a canonical function of repelling growing axons from the CNS midline. The full-length Slit (Slit-FL) is cleaved into Slit-N and Slit-C fragments, which have potentially distinct functions via different receptors. Here, we report that the BMP-1/Tolloid family metalloprotease Tolkin (Tok) is responsible for Slit proteolysis in vivo and in vitro. In Drosophilatok mutants lacking Slit cleavage, midline repulsion of axons occurs normally, confirming that Slit-FL is sufficient to repel axons. However, longitudinal axon guidance is highly disrupted in tok mutants and can be rescued by midline expression of Slit-N, suggesting that Slit is the primary substrate for Tok in the embryonic CNS. Transgenic restoration of Slit-N or Slit-C does not repel axons in Slit-null flies. Slit-FL and Slit-N are both biologically active cues with distinct axon guidance functions in vivo Slit signaling is used in diverse biological processes; therefore, differentiating between Slit-FL and Slit fragments will be essential for evaluating Slit function in broader contexts.
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Affiliation(s)
| | | | | | | | | | - Thomas Kidd
- Department of Biology/MS 314, University of Nevada, 1664 North Virginia Street, Reno, NV 89557, USA
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5
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Plazaola-Sasieta H, Zhu Q, Gaitán-Peñas H, Rios M, Estévez R, Morey M. Drosophila ClC-a is required in glia of the stem cell niche for proper neurogenesis and wiring of neural circuits. Glia 2019; 67:2374-2398. [PMID: 31479171 PMCID: PMC6851788 DOI: 10.1002/glia.23691] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 01/01/2023]
Abstract
Glial cells form part of the neural stem cell niche and express a wide variety of ion channels; however, the contribution of these channels to nervous system development is poorly understood. We explored the function of the Drosophila ClC‐a chloride channel, since its mammalian ortholog CLCN2 is expressed in glial cells, and defective channel function results in leukodystrophies, which in humans are accompanied by cognitive impairment. We found that ClC‐a was expressed in the niche in cortex glia, which are closely associated with neurogenic tissues. Characterization of loss‐of‐function ClC‐a mutants revealed that these animals had smaller brains and widespread wiring defects. We showed that ClC‐a is required in cortex glia for neurogenesis in neuroepithelia and neuroblasts, and identified defects in a neuroblast lineage that generates guidepost glial cells essential for photoreceptor axon guidance. We propose that glia‐mediated ionic homeostasis could nonautonomously affect neurogenesis, and consequently, the correct assembly of neural circuits.
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Affiliation(s)
- Haritz Plazaola-Sasieta
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Qi Zhu
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Héctor Gaitán-Peñas
- Departament de Ciencies Fisiològiques, Genes, Disease and Therapy Program IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Martín Rios
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Raúl Estévez
- Departament de Ciencies Fisiològiques, Genes, Disease and Therapy Program IDIBELL-Institute of Neurosciences, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Morey
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,Institut de Biomedicina de la Universitat de Barcelona (IBUB), Programa de Biologia Integrativa, Barcelona, Spain
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6
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Mineo A, Furriols M, Casanova J. The trigger (and the restriction) of Torso RTK activation. Open Biol 2018; 8:180180. [PMID: 30977718 PMCID: PMC6303783 DOI: 10.1098/rsob.180180] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/08/2018] [Indexed: 01/09/2023] Open
Abstract
The Torso pathway is an ideal model of receptor tyrosine kinase systems, in particular when addressing questions such as how receptor activity is turned on and, equally important, how it is restricted, how different outcomes can be generated from a single signal, and the extent to which gene regulation by signalling pathways relies on the relief of transcriptional repression. In this regard, we considered it pertinent to single out the fundamental notions learned from the Torso pathway beyond the specificities of this system (Furriols and Casanova 2003 EMBO J. 22, 1947-1952. ( doi:10.1093/emboj/cdg224 )). Since then, the Torso system has gained relevance and its implications beyond its original involvement in morphogenesis and into many disciplines such as oncogenesis, hormone control and neurobiology are now acknowledged. Thus, we believe that it is timely to highlight additional notions supported by new findings and to draw attention to future prospects. Given the late development of research in the field, we wish to devote this review to the events leading to the activation of the Torso receptor, the main focus of our most recent work.
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Affiliation(s)
- Alessandro Mineo
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
| | - Marc Furriols
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
| | - Jordi Casanova
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
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7
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Insight into Notch Signaling Steps That Involve pecanex from Dominant-Modifier Screens in Drosophila. Genetics 2018; 209:1099-1119. [PMID: 29853475 DOI: 10.1534/genetics.118.300935] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/22/2018] [Indexed: 12/14/2022] Open
Abstract
Notch signaling plays crucial roles in intercellular communications. In Drosophila, the pecanex (pcx) gene, which encodes an evolutionarily conserved multi-pass transmembrane protein, appears to be required to activate Notch signaling in some contexts, especially during neuroblast segregation in the neuroectoderm. Although Pcx has been suggested to contribute to endoplasmic reticulum homeostasis, its functions remain unknown. Here, to elucidate these roles, we performed genetic modifier screens of pcx We found that pcx heterozygotes lacking its maternal contribution exhibit cold-sensitive lethality, which is attributed to a reduction in Notch signaling at decreased temperatures. Using sets of deletions that uncover most of the second and third chromosomes, we identified four enhancers and two suppressors of the pcx cold-sensitive lethality. Among these, five genes encode known Notch-signaling components: big brain, Delta (Dl), neuralized (neur), Brother of Bearded A (BobA), a member of the Bearded (Brd) family, and N-ethylmaleimide-sensitive factor 2 (Nsf2). We showed that BobA suppresses Dl endocytosis during neuroblast segregation in the neuroectoderm, as Brd family genes reportedly do in the mesoderm for mesectoderm specification. Analyses of Nsf2, a key regulator of vesicular fusion, suggested a novel role in neuroblast segregation, which is distinct from Nsf2's previously reported role in imaginal tissues. Finally, jim lovell, which encodes a potential transcription factor, may play a role in Notch signaling during neuroblast segregation. These results reveal new research avenues for Pcx functions and Notch signaling.
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8
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Haines JE, Eisen MB. Patterns of chromatin accessibility along the anterior-posterior axis in the early Drosophila embryo. PLoS Genet 2018; 14:e1007367. [PMID: 29727464 PMCID: PMC5955596 DOI: 10.1371/journal.pgen.1007367] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 05/16/2018] [Accepted: 04/17/2018] [Indexed: 12/20/2022] Open
Abstract
As the Drosophila embryo transitions from the use of maternal RNAs to zygotic transcription, domains of open chromatin, with relatively low nucleosome density and specific histone marks, are established at promoters and enhancers involved in patterned embryonic transcription. However it remains unclear how regions of activity are established during early embryogenesis, and if they are the product of spatially restricted or ubiquitous processes. To shed light on this question, we probed chromatin accessibility across the anterior-posterior axis (A-P) of early Drosophila melanogaster embryos by applying a transposon based assay for chromatin accessibility (ATAC-seq) to anterior and posterior halves of hand-dissected, cellular blastoderm embryos. We find that genome-wide chromatin accessibility is highly similar between the two halves, with regions that manifest significant accessibility in one half of the embryo almost always accessible in the other half, even for promoters that are active in exclusively one half of the embryo. These data support previous studies that show that chromatin accessibility is not a direct result of activity, and point to a role for ubiquitous factors or processes in establishing chromatin accessibility at promoters in the early embryo. However, in concordance with similar works, we find that at enhancers active exclusively in one half of the embryo, we observe a significant skew towards greater accessibility in the region of their activity, highlighting the role of patterning factors such as Bicoid in this process.
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Affiliation(s)
- Jenna E. Haines
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States of America
| | - Michael B. Eisen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States of America
- Department of Integrative Biology, University of California, Berkeley, Berkeley, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States of America
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9
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Johnson TK, Henstridge MA, Warr CG. MACPF/CDC proteins in development: Insights from Drosophila torso-like. Semin Cell Dev Biol 2017; 72:163-170. [DOI: 10.1016/j.semcdb.2017.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 05/01/2017] [Accepted: 05/11/2017] [Indexed: 01/08/2023]
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10
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Pearson JC, McKay DJ, Lieb JD, Crews ST. Chromatin profiling of Drosophila CNS subpopulations identifies active transcriptional enhancers. Development 2017; 143:3723-3732. [PMID: 27802137 DOI: 10.1242/dev.136895] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 08/30/2016] [Indexed: 12/25/2022]
Abstract
One of the key issues in studying transcriptional regulation during development is how to employ genome-wide assays that reveals sites of open chromatin and transcription factor binding to efficiently identify biologically relevant genes and enhancers. Analysis of Drosophila CNS midline cell development provides a useful system for studying transcriptional regulation at the genomic level due to a large, well-characterized set of midline-expressed genes and in vivo validated enhancers. In this study, FAIRE-seq on FACS-purified midline cells was performed and the midline FAIRE data were compared with whole-embryo FAIRE data. We find that regions of the genome with a strong midline FAIRE peak and weak whole-embryo FAIRE peak overlap with known midline enhancers and provide a useful predictive tool for enhancer identification. In a complementary analysis, we compared a large dataset of fragments that drive midline expression in vivo with the FAIRE data. Midline enhancer fragments with a midline FAIRE peak tend to be near midline-expressed genes, whereas midline enhancers without a midline FAIRE peak were often distant from midline-expressed genes and unlikely to drive midline transcription in vivo.
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Affiliation(s)
- Joseph C Pearson
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.,Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - Daniel J McKay
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA .,Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.,Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - Jason D Lieb
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - Stephen T Crews
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA .,Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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11
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Rogers WA, Goyal Y, Yamaya K, Shvartsman SY, Levine MS. Uncoupling neurogenic gene networks in the Drosophila embryo. Genes Dev 2017; 31:634-638. [PMID: 28428262 PMCID: PMC5411704 DOI: 10.1101/gad.297150.117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 03/20/2017] [Indexed: 12/22/2022]
Abstract
The EGF signaling pathway specifies neuronal identities in the Drosophila embryo by regulating developmental patterning genes such as intermediate neuroblasts defective (ind). EGFR is activated in the ventral midline and neurogenic ectoderm by the Spitz ligand, which is processed by the Rhomboid protease. CRISPR/Cas9 was used to delete defined rhomboid enhancers mediating expression at each site of Spitz processing. Surprisingly, the neurogenic ectoderm, not the ventral midline, was found to be the dominant source of EGF patterning activity. We suggest that Drosophila is undergoing an evolutionary transition in central nervous system (CNS)-organizing activity from the ventral midline to the neurogenic ectoderm.
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Affiliation(s)
- William A Rogers
- Department of Molecular Biology, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yogesh Goyal
- Department of Chemical and Biological Engineering, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Kei Yamaya
- Department of Molecular Biology, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Stanislav Y Shvartsman
- Department of Chemical and Biological Engineering, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Michael S Levine
- Department of Molecular Biology, Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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12
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Mino RE, Rogers SL, Risinger AL, Rohena C, Banerjee S, Bhat MA. Drosophila Ringmaker regulates microtubule stabilization and axonal extension during embryonic development. J Cell Sci 2016; 129:3282-94. [PMID: 27422099 DOI: 10.1242/jcs.187294] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/13/2016] [Indexed: 11/20/2022] Open
Abstract
Axonal growth and targeting are fundamental to the organization of the nervous system, and require active engagement of the cytoskeleton. Polymerization and stabilization of axonal microtubules is central to axonal growth and maturation of neuronal connectivity. Studies have suggested that members of the tubulin polymerization promoting protein (TPPP, also known as P25α) family are involved in cellular process extension. However, no in vivo knockout data exists regarding its role in axonal growth during development. Here, we report the characterization of Ringmaker (Ringer; CG45057), the only Drosophila homolog of long p25α proteins. Immunohistochemical analyses indicate that Ringer expression is dynamically regulated in the embryonic central nervous system (CNS). ringer-null mutants show cell misplacement, and errors in axonal extension and targeting. Ultrastructural examination of ringer mutants revealed defective microtubule morphology and organization. Primary neuronal cultures of ringer mutants exhibit defective axonal extension, and Ringer expression in cells induced microtubule stabilization and bundling into rings. In vitro assays showed that Ringer directly affects tubulin, and promotes microtubule bundling and polymerization. Together, our studies uncover an essential function of Ringer in axonal extension and targeting through proper microtubule organization.
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Affiliation(s)
- Rosa E Mino
- Department of Physiology, University of Texas School of Medicine, Health Science Center, San Antonio, TX 78229, USA
| | - Stephen L Rogers
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - April L Risinger
- Department of Pharmacology, University of Texas School of Medicine, Health Science Center, San Antonio, TX 78229, USA
| | - Cristina Rohena
- Department of Pharmacology, University of Texas School of Medicine, Health Science Center, San Antonio, TX 78229, USA Department of Medicine, University of California, San Diego, CA 92093, USA
| | - Swati Banerjee
- Department of Physiology, University of Texas School of Medicine, Health Science Center, San Antonio, TX 78229, USA
| | - Manzoor A Bhat
- Department of Physiology, University of Texas School of Medicine, Health Science Center, San Antonio, TX 78229, USA
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13
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Syed DS, Gowda SBM, Reddy OV, Reichert H, VijayRaghavan K. Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking. eLife 2016; 5:e11572. [PMID: 26926907 PMCID: PMC4805548 DOI: 10.7554/elife.11572] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 02/28/2016] [Indexed: 12/29/2022] Open
Abstract
Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map. DOI:http://dx.doi.org/10.7554/eLife.11572.001 Nerve cells enable us to both sense the world around us and to move about it. The nerves responsible for movement are called motor neurons. While one end of a motor neuron stimulates the muscle it is connected to, the other end receives signals from nerves in the spinal cord that relay messages about movement from the brain. Motor neuron connections in the spinal cord, or its equivalent in insects, the ventral nerve cord, are organized into an arrangement known as a myotopic map, which reflects the anatomical arrangement of the muscles in the body. Much remains to be learnt about how these maps form. Syed et al. have investigated how the myotopic map develops for motor neurons in the legs of fruit flies by reducing the function of chosen genes in the ventral nerve cord and asking how this affects the myotopic map. The experiments disrupted a signaling system called the Semaphorin signaling pathway that guides motor neurons to the right target muscle and consists of different receptor-signaling molecule pairs. By looking for flies with an abnormal walk and with disrupted motor neuron organization, Syed et al. identified receptor-signal pairs that guide motor neurons to different leg muscles. Specific receptor-signal pairs also guide the organisation of motor neurons in the ventral nerve cord. This guidance depends on when neurons are ‘born’. While a receptor-signal pair targets early born neurons to one leg muscle, the same receptor-signal pair regulates a different aspect of guidance in late-born neurons. Cells called glia, which are related to neurons, also help to position the connections of late-born motor neurons in the ventral nerve cord. Overall, the Semaphorin signaling system assists communication both within motor neurons and between glia cells and motor neurons during the formation of the myotopic map for leg motor neurons. These discoveries open new avenues of investigation into how else these cells communicate with each other to aid the development and organization of motor neurons. DOI:http://dx.doi.org/10.7554/eLife.11572.002
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Affiliation(s)
- Durafshan Sakeena Syed
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Swetha B M Gowda
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.,Manipal University, Manipal, India
| | - O Venkateswara Reddy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | | | - K VijayRaghavan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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14
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Schachtner LT, Sola IE, Forand D, Antonacci S, Postovit AJ, Mortimer NT, Killian DJ, Olesnicky EC. Drosophila Shep and C. elegans SUP-26 are RNA-binding proteins that play diverse roles in nervous system development. Dev Genes Evol 2015; 225:319-30. [PMID: 26271810 DOI: 10.1007/s00427-015-0514-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 08/03/2015] [Indexed: 12/14/2022]
Abstract
The Caenorhabditis elegans gene sup-26 encodes a well-conserved RNA-recognition motif-containing RNA-binding protein (RBP) that functions in dendrite morphogenesis of the PVD sensory neuron. The Drosophila ortholog of sup-26, alan shepard (shep), is expressed throughout the nervous system and has been shown to regulate neuronal remodeling during metamorphosis. Here, we extend these studies to show that sup-26 and shep are required for the development of diverse cell types within the nematode and fly nervous systems during embryonic and larval stages. We ascribe roles for sup-26 in regulating dendrite number and the expression of genes involved in mechanosensation within the nematode peripheral nervous system. We also find that in Drosophila, shep regulates dendrite length and branch order of nociceptive neurons, regulates the organization of neuronal clusters of the peripheral nervous system and the organization of axons within the ventral nerve cord. Taken together, our results suggest that shep/sup-26 orthologs play diverse roles in neural development across animal species. Moreover, we discuss potential roles for shep/sup-26 orthologs in the human nervous system.
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Affiliation(s)
- Logan T Schachtner
- Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918, USA
| | - Ismail E Sola
- Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918, USA
| | - Daniel Forand
- Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918, USA
| | - Simona Antonacci
- Department of Molecular Biology, Colorado College, 14 East Cache La Poudre Street, Colorado Springs, CO, 80903, USA
| | - Adam J Postovit
- Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918, USA
| | - Nathan T Mortimer
- Department of Biological Sciences, University of Denver, Denver, CO, 80208, USA.,School of Biological Sciences, Illinois State University, Normal, IL, 61790, USA
| | - Darrell J Killian
- Department of Molecular Biology, Colorado College, 14 East Cache La Poudre Street, Colorado Springs, CO, 80903, USA.
| | - Eugenia C Olesnicky
- Department of Biology, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO, 80918, USA.
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15
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Brunet T, Lauri A, Arendt D. Did the notochord evolve from an ancient axial muscle? The axochord hypothesis. Bioessays 2015; 37:836-50. [PMID: 26172338 PMCID: PMC5054868 DOI: 10.1002/bies.201500027] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 06/03/2015] [Accepted: 06/05/2015] [Indexed: 12/20/2022]
Abstract
The origin of the notochord is one of the key remaining mysteries of our evolutionary ancestry. Here, we present a multi‐level comparison of the chordate notochord to the axochord, a paired axial muscle spanning the ventral midline of annelid worms and other invertebrates. At the cellular level, comparative molecular profiling in the marine annelids P. dumerilii and C. teleta reveals expression of similar, specific gene sets in presumptive axochordal and notochordal cells. These cells also occupy corresponding positions in a conserved anatomical topology and undergo similar morphogenetic movements. At the organ level, a detailed comparison of bilaterian musculatures reveals that most phyla form axochord‐like muscles, suggesting that such a muscle was already present in urbilaterian ancestors. Integrating comparative evidence at the cell and organ level, we propose that the notochord evolved by modification of a ventromedian muscle followed by the assembly of an axial complex supporting swimming in vertebrate ancestors.
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Affiliation(s)
- Thibaut Brunet
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Antonella Lauri
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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16
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Specialized Cortex Glial Cells Accumulate Lipid Droplets in Drosophila melanogaster. PLoS One 2015; 10:e0131250. [PMID: 26148013 PMCID: PMC4493057 DOI: 10.1371/journal.pone.0131250] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/29/2015] [Indexed: 12/30/2022] Open
Abstract
Lipid droplets (LDs) are common organelles of the majority of eukaryotic cell types. Their biological significance has been extensively studied in mammalian liver cells and white adipose tissue. Although the central nervous system contains the highest relative amount and the largest number of different lipid species, neither the spatial nor the temporal distribution of LDs has been described. In this study, we used the brain of the fruitfly, Drosophila melanogaster, to investigate the neuroanatomy of LDs. We demonstrated that LDs are exclusively localised in glial cells but not in neurons in the larval nervous system. We showed that the brain’s LD pool, rather than being constant, changes dynamically during development and reaches its highest value at the beginning of metamorphosis. LDs are particularly enriched in cortex glial cells located close to the brain surface. These specialized superficial cortex glial cells contain the highest amount of LDs among glial cell types and encapsulate neuroblasts and their daughter cells. Superficial cortex glial cells, combined with subperineurial glial cells, express the Drosophila fatty acid binding protein (Dfabp), as we have demonstrated through light- and electron microscopic immunocytochemistry. To the best of our best knowledge this is the first study that describes LD neuroanatomy in the Drosophila larval brain.
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17
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Stratoulias V, Heino TI. MANF silencing, immunity induction or autophagy trigger an unusual cell type in metamorphosing Drosophila brain. Cell Mol Life Sci 2014; 72:1989-2004. [PMID: 25511196 PMCID: PMC4412683 DOI: 10.1007/s00018-014-1789-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 11/17/2014] [Accepted: 11/20/2014] [Indexed: 12/31/2022]
Abstract
Glia are abundant cells in the brain of animals ranging from flies to humans. They perform conserved functions not only in neural development and wiring, but also in brain homeostasis. Here we show that by manipulating gene expression in glia, a previously unidentified cell type appears in the Drosophila brain during metamorphosis. More specifically, this cell type appears in three contexts: (1) after the induction of either immunity, or (2) autophagy, or (3) by silencing of neurotrophic factor DmMANF in glial cells. We call these cells MANF immunoreactive Cells (MiCs). MiCs are migratory based on their shape, appearance in brain areas where no cell bodies exist and the nuclear localization of dSTAT. They are labeled with a unique set of molecular markers including the conserved neurotrophic factor DmMANF and the transcription factor Zfh1. They possess the nuclearly localized protein Relish, which is the hallmark of immune response activation. They also express the conserved engulfment receptor Draper, therefore indicating that they are potentially phagocytic. Surprisingly, they do not express any of the common glial and neuronal markers. In addition, ultrastructural studies show that MiCs are extremely rich in lysosomes. Our findings reveal critical molecular and functional components of an unusual cell type in the Drosophila brain. We suggest that MiCs resemble macrophages/hemocytes and vertebrate microglia based on their appearance in the brain upon genetically challenged conditions and the expression of molecular markers. Interestingly, macrophages/hemocytes or microglia-like cells have not been reported in the fly nervous system before.
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Affiliation(s)
- Vassilis Stratoulias
- Department of Biosciences, University of Helsinki, P.O. Box 56, Viikinkaari 5, 00014, Helsinki, Finland,
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18
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Heckscher ES, Long F, Layden MJ, Chuang CH, Manning L, Richart J, Pearson JC, Crews ST, Peng H, Myers E, Doe CQ. Atlas-builder software and the eNeuro atlas: resources for developmental biology and neuroscience. Development 2014; 141:2524-32. [PMID: 24917506 DOI: 10.1242/dev.108720] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A major limitation in understanding embryonic development is the lack of cell type-specific markers. Existing gene expression and marker atlases provide valuable tools, but they typically have one or more limitations: a lack of single-cell resolution; an inability to register multiple expression patterns to determine their precise relationship; an inability to be upgraded by users; an inability to compare novel patterns with the database patterns; and a lack of three-dimensional images. Here, we develop new 'atlas-builder' software that overcomes each of these limitations. A newly generated atlas is three-dimensional, allows the precise registration of an infinite number of cell type-specific markers, is searchable and is open-ended. Our software can be used to create an atlas of any tissue in any organism that contains stereotyped cell positions. We used the software to generate an 'eNeuro' atlas of the Drosophila embryonic CNS containing eight transcription factors that mark the major CNS cell types (motor neurons, glia, neurosecretory cells and interneurons). We found neuronal, but not glial, nuclei occupied stereotyped locations. We added 75 new Gal4 markers to the atlas to identify over 50% of all interneurons in the ventral CNS, and these lines allowed functional access to those interneurons for the first time. We expect the atlas-builder software to benefit a large proportion of the developmental biology community, and the eNeuro atlas to serve as a publicly accessible hub for integrating neuronal attributes - cell lineage, gene expression patterns, axon/dendrite projections, neurotransmitters--and linking them to individual neurons.
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Affiliation(s)
- Ellie S Heckscher
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Fuhui Long
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Michael J Layden
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Chein-Hui Chuang
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Laurina Manning
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Jourdain Richart
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
| | - Joseph C Pearson
- Program in Molecular Biology and Biophysics, Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 275995, USA
| | - Stephen T Crews
- Program in Molecular Biology and Biophysics, Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 275995, USA
| | - Hanchuan Peng
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eugene Myers
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403, USA
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19
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Enhancer diversity and the control of a simple pattern of Drosophila CNS midline cell expression. Dev Biol 2014; 392:466-82. [PMID: 24854999 DOI: 10.1016/j.ydbio.2014.05.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 05/06/2014] [Accepted: 05/13/2014] [Indexed: 01/13/2023]
Abstract
Transcriptional enhancers integrate information derived from transcription factor binding to control gene expression. One key question concerns the extent of trans- and cis-regulatory variation in how co-expressed genes are controlled. The Drosophila CNS midline cells constitute a group of neurons and glia in which expression changes can be readily characterized during specification and differentiation. Using a transgenic approach, we compare the cis-regulation of multiple genes expressed in the Drosophila CNS midline primordium cells, and show that while the expression patterns may appear alike, the target genes are not equivalent in how these common expression patterns are achieved. Some genes utilize a single enhancer that promotes expression in all midline cells, while others utilize multiple enhancers with distinct spatial, temporal, and quantitative contributions. Two regulators, Single-minded and Notch, play key roles in controlling early midline gene expression. While Single-minded is expected to control expression of most, if not all, midline primordium-expressed genes, the role of Notch in directly controlling midline transcription is unknown. Midline primordium expression of the rhomboid gene is dependent on cell signaling by the Notch signaling pathway. Mutational analysis of a rhomboid enhancer reveals at least 5 distinct types of functional cis-control elements, including a binding site for the Notch effector, Suppressor of Hairless. The results suggest a model in which Notch/Suppressor of Hairless levels are insufficient to activate rhomboid expression by itself, but does so in conjunction with additional factors, some of which, including Single-minded, provide midline specificity to Notch activation. Similarly, a midline glial enhancer from the argos gene, which is dependent on EGF/Spitz signaling, is directly regulated by contributions from both Pointed, the EGF transcriptional effector, and Single-minded. In contrast, midline primordium expression of other genes shows a strong dependence on Single-minded and varying combinations of additional transcription factors. Thus, Single-minded directly regulates midline primordium-expressed genes, but in some cases plays a primary role in directing target gene midline expression, and in others provides midline specificity to cell signaling inputs.
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20
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A comparison of midline and tracheal gene regulation during Drosophila development. PLoS One 2014; 9:e85518. [PMID: 24465586 PMCID: PMC3896416 DOI: 10.1371/journal.pone.0085518] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 11/28/2013] [Indexed: 11/19/2022] Open
Abstract
Within the Drosophila embryo, two related bHLH-PAS proteins, Single-minded and Trachealess, control development of the central nervous system midline and the trachea, respectively. These two proteins are bHLH-PAS transcription factors and independently form heterodimers with another bHLH-PAS protein, Tango. During early embryogenesis, expression of Single-minded is restricted to the midline and Trachealess to the trachea and salivary glands, whereas Tango is ubiquitously expressed. Both Single-minded/Tango and Trachealess/Tango heterodimers bind to the same DNA sequence, called the CNS midline element (CME) within cis-regulatory sequences of downstream target genes. While Single-minded/Tango and Trachealess/Tango activate some of the same genes in their respective tissues during embryogenesis, they also activate a number of different genes restricted to only certain tissues. The goal of this research is to understand how these two related heterodimers bind different enhancers to activate different genes, thereby regulating the development of functionally diverse tissues. Existing data indicates that Single-minded and Trachealess may bind to different co-factors restricted to various tissues, causing them to interact with the CME only within certain sequence contexts. This would lead to the activation of different target genes in different cell types. To understand how the context surrounding the CME is recognized by different bHLH-PAS heterodimers and their co-factors, we identified and analyzed novel enhancers that drive midline and/or tracheal expression and compared them to previously characterized enhancers. In addition, we tested expression of synthetic reporter genes containing the CME flanked by different sequences. Taken together, these experiments identify elements overrepresented within midline and tracheal enhancers and suggest that sequences immediately surrounding a CME help dictate whether a gene is expressed in the midline or trachea.
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21
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Manning AJ, Peters KA, Peifer M, Rogers SL. Regulation of epithelial morphogenesis by the G protein-coupled receptor mist and its ligand fog. Sci Signal 2013; 6:ra98. [PMID: 24222713 DOI: 10.1126/scisignal.2004427] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Epithelial morphogenesis is essential for shaping organs and tissues and for establishment of the three embryonic germ layers during gastrulation. Studies of gastrulation in Drosophila have provided insight into how epithelial morphogenesis is governed by developmental patterning mechanisms. We developed an assay to recapitulate morphogenetic shape changes in individual cultured cells and used RNA interference-based screening to identify Mist, a Drosophila G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) that transduces signals from the secreted ligand Folded gastrulation (Fog) in cultured cells. Mist functioned in Fog-dependent embryonic morphogenesis, and the transcription factor Snail regulated expression of mist in zygotes. Our data revealed how a cell fate transcriptional program acts through a ligand-GPCR pair to stimulate epithelial morphogenetic shape changes.
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Affiliation(s)
- Alyssa J Manning
- 1Department of Biology, University of North Carolina at Chapel Hill, CB# 3280, Fordham Hall, South Road, Chapel Hill, NC 27599-3280, USA
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22
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Perea D, Molohon K, Edwards K, Díaz-Benjumea FJ. Multiple roles of the gene zinc finger homeodomain-2 in the development of the Drosophila wing. Mech Dev 2013; 130:467-81. [PMID: 23811114 DOI: 10.1016/j.mod.2013.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/05/2013] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
The gene zfh2 and its human homolog Atbf1 encode huge molecules with several homeo- and zinc finger domains. It has been reported that they play important roles in neural differentiation and promotion of apoptosis in several tissues of both humans and flies. In the Drosophila wing imaginal disc, Zfh2 is expressed in a dynamic pattern and previous results suggest that it is involved is proximal-distal patterning. In this report we go further in the analysis of the function of this gene in wing development, performing ectopic expression experiments and studying its effects in genes involved in wing development. Our results suggest that Zfh2 plays an important role controlling the expression of several wing genes and in the specification of those cellular properties that define the differences in cell proliferation between proximal and distal domains of the wing disc.
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Affiliation(s)
- Daniel Perea
- Centro de Biología Molecular-Severo Ochoa, Universidad Autónoma-Cantoblanco, 28049 Madrid, Spain
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23
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Hong JW, Park KW, Levine MS. Temporal regulation of single-minded target genes in the ventral midline of the Drosophila central nervous system. Dev Biol 2013; 380:335-43. [PMID: 23701883 DOI: 10.1016/j.ydbio.2013.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/11/2013] [Accepted: 05/13/2013] [Indexed: 12/21/2022]
Abstract
Differentiation of a specific organ or tissue requires sequential activation of regulatory genes. However, little is known about how serial gene expression is temporally regulated. Here, we present evidence that differential expression of single-minded (sim) target genes can be attributed, in part, to the number of Sim and Tango (Tgo) heterodimer binding sites within their enhancer regions. The Sim, termed a master regulator, directs ventral midline differentiation of Drosophila central nervous system (CNS). According to data on the onset timing of ventral midline gene expression, sim target genes are classified into at least 2 groups (early and late). The sim and rhomboid (rho) genes are activated during early midline differentiation whereas orthodenticle (otd), CG10249, and slit (sli) genes undergo activation during later stages of midline differentiation. Germline transformation and in situ hybridization with transgenic embryos demonstrate that enhancers activating sim and rho expression contain 4 Sim-Tgo binding sites whereas only 1 Sim-Tgo binding site is found in an enhancer of sli. A mutagenized version of the rho enhancer lacking either 1, 2, or 3 Sim-Tgo binding sites mediated progressively more delayed expression of a lacZ reporter gene in the ventral midline. In contrast, a modified sli enhancer displayed progressively earlier onset of lacZ expression when 1, 2, or 3 more Sim-Tgo binding sites were added. Taken together, these results suggest that the number of Sim-Tgo-binding sites is decisive in determining the timing of gene expression in the developing ventral midline. We also discuss a combinatorial model accounting for the sequential expression of sim target genes.
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Affiliation(s)
- Joung-Woo Hong
- Graduate School of East-West Medical Science, Kyung Hee University, Yongin 446-701, South Korea.
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24
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Bjorum SM, Simonette RA, Alanis R, Wang JE, Lewis BM, Trejo MH, Hanson KA, Beckingham KM. The Drosophila BTB domain protein Jim Lovell has roles in multiple larval and adult behaviors. PLoS One 2013; 8:e61270. [PMID: 23620738 PMCID: PMC3631165 DOI: 10.1371/journal.pone.0061270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 03/06/2013] [Indexed: 02/06/2023] Open
Abstract
Innate behaviors have their origins in the specification of neural fates during development. Within Drosophila, BTB (Bric-a-brac,Tramtrack, Broad) domain proteins such as Fruitless are known to play key roles in the neural differentiation underlying such responses. We previously identified a gene, which we have termed jim lovell (lov), encoding a BTB protein with a role in gravity responses. To understand more fully the behavioral roles of this gene we have investigated its function through several approaches. Transcript and protein expression patterns have been examined and behavioral phenotypes of new lov mutations have been characterized. Lov is a nuclear protein, suggesting a role as a transcriptional regulator, as for other BTB proteins. In late embryogenesis, Lov is expressed in many CNS and PNS neurons. An examination of the PNS expression indicates that lov functions in the late specification of several classes of sensory neurons. In particular, only two of the five abdominal lateral chordotonal neurons express Lov, predicting functional variation within this highly similar group. Surprisingly, Lov is also expressed very early in embryogenesis in ways that suggests roles in morphogenetic movements, amnioserosa function and head neurogenesis. The phenotypes of two new lov mutations that delete adjacent non-coding DNA regions are strikingly different suggesting removal of different regulatory elements. In lov47, Lov expression is lost in many embryonic neurons including the two lateral chordotonal neurons. lov47 mutant larvae show feeding and locomotor defects including spontaneous backward movement. Adult lov47 males perform aberrant courtship behavior distinguished by courtship displays that are not directed at the female. lov47 adults also show more defective negative gravitaxis than the previously isolated lov91Y mutant. In contrast, lov66 produces largely normal behavior but severe female sterility associated with ectopic lov expression in the ovary. We propose a negative regulatory role for the DNA deleted in lov66.
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Affiliation(s)
- Sonia M. Bjorum
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Rebecca A. Simonette
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Raul Alanis
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Jennifer E. Wang
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Benjamin M. Lewis
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Michael H. Trejo
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Keith A. Hanson
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
| | - Kathleen M. Beckingham
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, United States of America
- * E-mail:
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25
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Drosophila neuroligin 2 is required presynaptically and postsynaptically for proper synaptic differentiation and synaptic transmission. J Neurosci 2013; 32:16018-30. [PMID: 23136438 DOI: 10.1523/jneurosci.1685-12.2012] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Trans-synaptic adhesion between Neurexins (Nrxs) and Neuroligins (Nlgs) is thought to be required for proper synapse organization and modulation, and mutations in several human Nlgs have shown association with autism spectrum disorders. Here we report the generation and phenotypic characterization of Drosophila neuroligin 2 (dnlg2) mutants. Loss of dnlg2 results in reduced bouton numbers, aberrant presynaptic and postsynaptic development at neuromuscular junctions (NMJs), and impaired synaptic transmission. In dnlg2 mutants, the evoked responses are decreased in amplitude, whereas the total active zone (AZ) numbers at the NMJ are comparable to wild type, suggesting a decrease in the release probability. Ultrastructurally, the presynaptic AZ number per bouton area and the postsynaptic density area are both increased in dnlg2 mutants, whereas the subsynaptic reticulum is reduced in volume. We show that both presynaptic and postsynaptic expression of Dnlg2 is required to restore synaptic growth and function in dnlg2 mutants. Postsynaptic expression of Dnlg2 in dnlg2 mutants and wild type leads to reduced bouton growth whereas presynaptic and postsynaptic overexpression in wild-type animals results in synaptic overgrowth. Since Nlgs have been shown to bind to Nrxs, we created double mutants. These mutants are viable and display phenotypes that closely resemble those of dnlg2 and dnrx single mutants. Our results provide compelling evidence that Dnlg2 functions both presynaptically and postsynaptically together with Neurexin to determine the proper number of boutons as well as the number of AZs and size of synaptic densities during the development of NMJs.
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Shen SP, Aleksic J, Russell S. Identifying targets of the Sox domain protein Dichaete in the Drosophila CNS via targeted expression of dominant negative proteins. BMC DEVELOPMENTAL BIOLOGY 2013; 13:1. [PMID: 23289785 PMCID: PMC3541953 DOI: 10.1186/1471-213x-13-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/03/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Group B Sox domain transcription factors play important roles in metazoan central nervous system development. They are, however, difficult to study as mutations often have pleiotropic effects and other Sox family members can mask phenotypes due to functional compensation. In Drosophila melanogaster, the Sox gene Dichaete is dynamically expressed in the embryonic CNS, where it is known to have functional roles in neuroblasts and the ventral midline. In this study, we use inducible dominant negative proteins in combination with ChIP, immunohistochemistry and genome-wide expression profiling to further dissect the role of Dichaete in these two tissues. RESULTS We generated two dominant negative Dichaete constructs, one lacking a DNA binding domain and the other fused to the Engrailed transcriptional repressor domain. We expressed these tissue-specifically in the midline and in neuroblasts using the UAS/GAL4 system, validating their use at the phenotypic level and with known target genes. Using ChIP and immunohistochemistry, we identified two new likely direct Dichaete target genes, commisureless in the midline and asense in the neuroectoderm. We performed genome-wide expression profiling in stage 8-9 embryos, identifying almost a thousand potential tissue-specific Dichaete targets, with half of these genes showing evidence of Dichaete binding in vivo. These include a number of genes with known roles in CNS development, including several components of the Notch, Wnt and EGFR signalling pathways. CONCLUSIONS As well as identifying commisureless as a target, our data indicate that Dichaete helps establish its expression during early midline development but has less effect on its established later expression, highlighting Dichaete action on tissue specific enhancers. An analysis of the broader range of candidate Dichaete targets indicates that Dichaete plays diverse roles in CNS development, with the 500 or so Dichaete-bound putative targets including a number of transcription factors, signalling pathway components and terminal differentiation genes. In the early neurectoderm we implicate Dichaete in the lateral inhibition pathway and show that Dichaete acts to repress the proneural gene asense. Our analysis also reveals that dominant negatives cause off-target effects, highlighting the need to use other experimental data for validating findings from dominant negative studies.
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Affiliation(s)
- Shih Pei Shen
- Department of Genetics, University of Cambridge, Cambridge, UK
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Manning L, Heckscher ES, Purice MD, Roberts J, Bennett AL, Kroll JR, Pollard JL, Strader ME, Lupton JR, Dyukareva AV, Doan PN, Bauer DM, Wilbur AN, Tanner S, Kelly JJ, Lai SL, Tran KD, Kohwi M, Laverty TR, Pearson JC, Crews ST, Rubin GM, Doe CQ. A resource for manipulating gene expression and analyzing cis-regulatory modules in the Drosophila CNS. Cell Rep 2012; 2:1002-13. [PMID: 23063363 PMCID: PMC3523218 DOI: 10.1016/j.celrep.2012.09.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 09/11/2012] [Accepted: 09/17/2012] [Indexed: 01/03/2023] Open
Abstract
Here, we describe the embryonic central nervous system expression of 5,000 GAL4 lines made using molecularly defined cis-regulatory DNA inserted into a single attP genomic location. We document and annotate the patterns in early embryos when neurogenesis is at its peak, and in older embryos where there is maximal neuronal diversity and the first neural circuits are established. We note expression in other tissues, such as the lateral body wall (muscle, sensory neurons, and trachea) and viscera. Companion papers report on the adult brain and larval imaginal discs, and the integrated data sets are available online (http://www.janelia.org/gal4-gen1). This collection of embryonically expressed GAL4 lines will be valuable for determining neuronal morphology and function. The 1,862 lines expressed in small subsets of neurons (<20/segment) will be especially valuable for characterizing interneuronal diversity and function, because although interneurons comprise the majority of all central nervous system neurons, their gene expression profile and function remain virtually unexplored.
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Affiliation(s)
- Laurina Manning
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Ellie S. Heckscher
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Maria D. Purice
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Jourdain Roberts
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Alysha L. Bennett
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Jason R. Kroll
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Jill L. Pollard
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Marie E. Strader
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Josh R. Lupton
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Anna V. Dyukareva
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Phuong Nam Doan
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - David M. Bauer
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Allison N. Wilbur
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Stephanie Tanner
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Jimmy J. Kelly
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Sen-Lin Lai
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Khoa D. Tran
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Minoree Kohwi
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
| | - Todd R. Laverty
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn VA 20147
| | - Joseph C. Pearson
- Program in Molecular Biology and Biophysics, Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Stephen T. Crews
- Program in Molecular Biology and Biophysics, Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Gerald M. Rubin
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn VA 20147
| | - Chris Q. Doe
- Institutes of Neuroscience and Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR 97403
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Fontana JR, Crews ST. Transcriptome analysis of Drosophila CNS midline cells reveals diverse peptidergic properties and a role for castor in neuronal differentiation. Dev Biol 2012; 372:131-42. [PMID: 23010511 DOI: 10.1016/j.ydbio.2012.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 08/28/2012] [Accepted: 09/13/2012] [Indexed: 11/17/2022]
Abstract
One of the key aspects of neuronal differentiation is the array of neurotransmitters and neurotransmitter receptors that each neuron possesses. One important goal of developmental neuroscience is to understand how these differentiated properties are established during development. In this paper, we use fluorescence activated cell sorting and RNA-seq to determine the transcriptome of the Drosophila CNS midline cells, which consist of a small number of well-characterized neurons and glia. These data revealed that midline cells express 9 neuropeptide precursor genes, 13 neuropeptide receptor genes, and 31 small-molecule neurotransmitter receptor genes. In situ hybridization and high-resolution confocal analyses were carried-out to determine the midline cell identity for these neuropeptides and the neuropeptide receptors. The results revealed a surprising level of diversity. Neuropeptide genes are expressed in a variety of midline cell types, including motoneurons, GABAergic interneurons, and midline glia. These data revealed previously unknown functional differences among the highly-related iVUM neurons. There also exist segmental differences in expression for the same neuronal sub-type. Similar experiments on midline-expressed neuropeptide receptor genes reveal considerable diversity in synaptic inputs. Multiple receptor types were expressed in midline interneurons and motoneurons, and, in one case, link feeding behavior to gut peristalsis and locomotion. There were also segmental differences, variations between the 3 iVUMs, and three hormone receptor genes were broadly expressed in most midline cells. The Drosophila Castor transcription factor is present at high levels in iVUM5, which is both GABAergic and expresses the short neuropeptide F precursor gene. Genetic and misexpression experiments indicated that castor specifically controls expression of the short neuropeptide F precursor gene, but does not affect iVUM cell fate or expression of Gad1. This indicates a novel function for castor in regulating neuropeptide gene expression.
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Affiliation(s)
- Joseph R Fontana
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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Watson JD, Crews ST. Formation and specification of a Drosophila dopaminergic precursor cell. Development 2012; 139:3316-25. [PMID: 22874915 DOI: 10.1242/dev.079525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dopaminergic neurons play important roles in animal behavior, including motivation, reward and locomotion. The Drosophila dopaminergic H-cell interneuron is an attractive system for studying the genetics of neural development because analysis is focused on a single neuronal cell type. Here we provide a mechanistic understanding of how MP3, the precursor to the H-cell, forms and acquires its identity. We show that the gooseberry/gooseberry-neuro (gsb/gsb-n) transcription factor genes act to specify MP3 cell fate. It is proposed that single-minded commits neuroectodermal cells to a midline fate, followed by a series of signaling events that result in the formation of a single gsb(+)/gsb-n(+) MP3 cell per segment. The wingless signaling pathway establishes a midline anterior domain by activating expression of the forkhead transcription factors sloppy paired 1 and sloppy paired 2. This is followed by hedgehog signaling that activates gsb/gsb-n expression in a subgroup of anterior cells. Finally, Notch signaling results in the selection of a single MP3, with the remaining cells becoming midline glia. In MP3, gsb/gsb-n direct H-cell development, in large part by activating expression of the lethal of scute and tailup H-cell regulatory genes. Thus, a series of signaling and transcriptional events result in the specification of a unique dopaminergic precursor cell. Additional genetic experiments indicate that the molecular mechanisms that govern MP3/H-cell development might also direct the development of non-midline dopaminergic neurons.
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Affiliation(s)
- Joseph D Watson
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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Kim MS, Kim JR, Kim D, Lander AD, Cho KH. Spatiotemporal network motif reveals the biological traits of developmental gene regulatory networks in Drosophila melanogaster. BMC SYSTEMS BIOLOGY 2012; 6:31. [PMID: 22548745 PMCID: PMC3434043 DOI: 10.1186/1752-0509-6-31] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 05/01/2012] [Indexed: 12/27/2022]
Abstract
Background Network motifs provided a “conceptual tool” for understanding the functional principles of biological networks, but such motifs have primarily been used to consider static network structures. Static networks, however, cannot be used to reveal time- and region-specific traits of biological systems. To overcome this limitation, we proposed the concept of a “spatiotemporal network motif,” a spatiotemporal sequence of network motifs of sub-networks which are active only at specific time points and body parts. Results On the basis of this concept, we analyzed the developmental gene regulatory network of the Drosophila melanogaster embryo. We identified spatiotemporal network motifs and investigated their distribution pattern in time and space. As a result, we found how key developmental processes are temporally and spatially regulated by the gene network. In particular, we found that nested feedback loops appeared frequently throughout the entire developmental process. From mathematical simulations, we found that mutual inhibition in the nested feedback loops contributes to the formation of spatial expression patterns. Conclusions Taken together, the proposed concept and the simulations can be used to unravel the design principle of developmental gene regulatory networks.
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Affiliation(s)
- Man-Sun Kim
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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Pearson JC, Watson JD, Crews ST. Drosophila melanogaster Zelda and Single-minded collaborate to regulate an evolutionarily dynamic CNS midline cell enhancer. Dev Biol 2012; 366:420-32. [PMID: 22537497 DOI: 10.1016/j.ydbio.2012.04.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/04/2012] [Accepted: 04/06/2012] [Indexed: 10/28/2022]
Abstract
The Drosophila Zelda transcription factor plays an important role in regulating transcription at the embryonic maternal-to-zygotic transition. However, expression of zelda continues throughout embryogenesis in cells including the developing CNS and trachea, but little is known about its post-blastoderm functions. In this paper, it is shown that zelda directly controls CNS midline and tracheal expression of the link (CG13333) gene, as well as link blastoderm expression. The link gene contains a 5' enhancer with multiple Zelda TAGteam binding sites that in vivo mutational studies show are required for link transcription. The link enhancer also has a binding site for the Single-minded:Tango and Trachealess:Tango bHLH-PAS proteins that also influences link midline and tracheal expression. These results provide an example of how a transcription factor (Single-minded or Trachealess) can interact with distinct co-regulatory proteins (Zelda or Sox/POU-homeodomain proteins) to control a similar pattern of expression of different target genes in a mechanistically different manner. While zelda and single-minded midline expression is well-conserved in Drosophila, midline expression of link is not well-conserved. Phylogenetic analysis of link expression suggests that ~60 million years ago, midline expression was nearly or completely absent, and first appeared in the melanogaster group (including D. melanogaster, D. yakuba, and D. erecta) >13 million years ago. The differences in expression are due, in part, to sequence polymorphisms in the link enhancer and likely due to altered binding of multiple transcription factors. Less than 6 million years ago, a second change occurred that resulted in high levels of expression in D. melanogaster. This change may be due to alterations in a putative Zelda binding site. Within the CNS, the zelda gene is alternatively spliced beginning at mid-embryogenesis into transcripts that encode a Zelda isoform missing three zinc fingers from the DNA binding domain. This may result in a protein with altered, possibly non-functional, DNA-binding properties. In summary, Zelda collaborates with bHLH-PAS proteins to directly regulate midline and tracheal expression of an evolutionary dynamic enhancer in the post-blastoderm embryo.
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Affiliation(s)
- Joseph C Pearson
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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Wheeler SR, Pearson JC, Crews ST. Time-lapse imaging reveals stereotypical patterns of Drosophila midline glial migration. Dev Biol 2012; 361:232-44. [PMID: 22061481 PMCID: PMC3246554 DOI: 10.1016/j.ydbio.2011.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 09/16/2011] [Accepted: 10/08/2011] [Indexed: 11/17/2022]
Abstract
The Drosophila CNS midline glia (MG) are multifunctional cells that ensheath and provide trophic support to commissural axons, and direct embryonic development by employing a variety of signaling molecules. These glia consist of two functionally distinct populations: the anterior MG (AMG) and posterior MG (PMG). Only the AMG ensheath axon commissures, whereas the function of the non-ensheathing PMG is unknown. The Drosophila MG have proven to be an excellent system for studying glial proliferation, cell fate, apoptosis, and axon-glial interactions. However, insight into how AMG migrate and acquire their specific positions within the axon-glial scaffold has been lacking. In this paper, we use time-lapse imaging, single-cell analysis, and embryo staining to comprehensively describe the proliferation, migration, and apoptosis of the Drosophila MG. We identified 3 groups of MG that differed in the trajectories of their initial inward migration: AMG that migrate inward and to the anterior before undergoing apoptosis, AMG that migrate inward and to the posterior to ensheath commissural axons, and PMG that migrate inward and to the anterior to contact the commissural axons before undergoing apoptosis. In a second phase of their migration, the surviving AMG stereotypically migrated posteriorly to specific positions surrounding the commissures, and their final position was correlated with their location prior to migration. Most noteworthy are AMG that migrated between the commissures from a ventral to a dorsal position. Single-cell analysis indicated that individual AMG possessed wide-ranging and elaborate membrane extensions that partially ensheathed both commissures. These results provide a strong foundation for future genetic experiments to identify mutants affecting MG development, particularly in guidance cues that may direct migration. Drosophila MG are homologous in structure and function to the glial-like cells that populate the vertebrate CNS floorplate, and study of Drosophila MG will provide useful insights into floorplate development and function.
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Affiliation(s)
- Scott R. Wheeler
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Joseph C. Pearson
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
| | - Stephen T. Crews
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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Zhang Y, Wheatley R, Fulkerson E, Tapp A, Estes PA. Mastermind mutations generate a unique constellation of midline cells within the Drosophila CNS. PLoS One 2011; 6:e26197. [PMID: 22046261 PMCID: PMC3203113 DOI: 10.1371/journal.pone.0026197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 09/22/2011] [Indexed: 02/05/2023] Open
Abstract
Background The Notch pathway functions repeatedly during the development of the central nervous system in metazoan organisms to control cell fate and regulate cell proliferation and asymmetric cell divisions. Within the Drosophila midline cell lineage, which bisects the two symmetrical halves of the central nervous system, Notch is required for initial cell specification and subsequent differentiation of many midline lineages. Methodology/Principal Findings Here, we provide the first description of the role of the Notch co-factor, mastermind, in the central nervous system midline of Drosophila. Overall, zygotic mastermind mutations cause an increase in midline cell number and decrease in midline cell diversity. Compared to mutations in other components of the Notch signaling pathway, such as Notch itself and Delta, zygotic mutations in mastermind cause the production of a unique constellation of midline cell types. The major difference is that midline glia form normally in zygotic mastermind mutants, but not in Notch and Delta mutants. Moreover, during late embryogenesis, extra anterior midline glia survive in zygotic mastermind mutants compared to wild type embryos. Conclusions/Significance This is an example of a mutation in a signaling pathway cofactor producing a distinct central nervous system phenotype compared to mutations in major components of the pathway.
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Affiliation(s)
- Yi Zhang
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Randi Wheatley
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Eric Fulkerson
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Amanda Tapp
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Patricia A. Estes
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
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Blenau W, Thamm M. Distribution of serotonin (5-HT) and its receptors in the insect brain with focus on the mushroom bodies: lessons from Drosophila melanogaster and Apis mellifera. ARTHROPOD STRUCTURE & DEVELOPMENT 2011; 40:381-394. [PMID: 21272662 DOI: 10.1016/j.asd.2011.01.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 01/05/2011] [Accepted: 01/14/2011] [Indexed: 05/30/2023]
Abstract
The biogenic amine serotonin (5-hydroxytryptamine, 5-HT) plays a key role in regulating and modulating various physiological and behavioral processes in both protostomes and deuterostomes. The specific functions of serotonin are mediated by its binding to and subsequent activation of membrane receptors. The vast majority of these receptors belong to the superfamily of G-protein-coupled receptors. We report here the in vivo expression pattern of a recently characterized 5-HT(1) receptor of the honeybee Apis mellifera (Am5-HT(1A)) in the mushroom bodies. In addition, we summarize current knowledge on the distribution of serotonin and serotonin receptor subtypes in the brain and specifically in the mushroom bodies of the fruit fly Drosophila melanogaster and the honeybee. Functional studies in these two species have shown that serotonergic signaling participates in various behaviors including aggression, sleep, circadian rhythms, responses to visual stimuli, and associative learning. The molecular, pharmacological, and functional properties of identified 5-HT receptor subtypes from A. mellifera and D. melanogaster will also be summarized in this review.
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Affiliation(s)
- Wolfgang Blenau
- Institute of Biochemistry and Biology, University of Potsdam, Germany.
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Stagg SB, Guardiola AR, Crews ST. Dual role for Drosophila lethal of scute in CNS midline precursor formation and dopaminergic neuron and motoneuron cell fate. Development 2011; 138:2171-83. [PMID: 21558367 DOI: 10.1242/dev.056507] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Dopaminergic neurons play important behavioral roles in locomotion, reward and aggression. The Drosophila H-cell is a dopaminergic neuron that resides at the midline of the ventral nerve cord. Both the H-cell and the glutamatergic H-cell sib are the asymmetric progeny of the MP3 midline precursor cell. H-cell sib cell fate is dependent on Notch signaling, whereas H-cell fate is Notch independent. Genetic analysis of genes that could potentially regulate H-cell fate revealed that the lethal of scute [l(1)sc], tailup and SoxNeuro transcription factor genes act together to control H-cell gene expression. The l(1)sc bHLH gene is required for all H-cell-specific gene transcription, whereas tailup acts in parallel to l(1)sc and controls genes involved in dopamine metabolism. SoxNeuro functions downstream of l(1)sc and controls expression of a peptide neurotransmitter receptor gene. The role of l(1)sc may be more widespread, as a l(1)sc mutant shows reductions in gene expression in non-midline dopaminergic neurons. In addition, l(1)sc mutant embryos possess defects in the formation of MP4-6 midline precursor and the median neuroblast stem cell, revealing a proneural role for l(1)sc in midline cells. The Notch-dependent progeny of MP4-6 are the mVUM motoneurons, and these cells also require l(1)sc for mVUM-specific gene expression. Thus, l(1)sc plays an important regulatory role in both neurogenesis and specifying dopaminergic neuron and motoneuron identities.
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Affiliation(s)
- Stephanie B Stagg
- Curriculum in Neurobiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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Slováková J, Carmena A. Canoe functions at the CNS midline glia in a complex with Shotgun and Wrapper-Nrx-IV during neuron-glia interactions. Development 2011; 138:1563-71. [PMID: 21389054 DOI: 10.1242/dev.056192] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Vertebrates and insects alike use glial cells as intermediate targets to guide growing axons. Similar to vertebrate oligodendrocytes, Drosophila midline glia ensheath and separate axonal commissures. Neuron-glia interactions are crucial during these events, although the proteins involved remain largely unknown. Here, we show that Canoe (Cno), the Drosophila ortholog of AF-6, and the DE-cadherin Shotgun (Shg) are highly restricted to the interface between midline glia and commissural axons. cno mutant analysis, genetic interactions and co-immunoprecipitation assays unveil Cno function as a novel regulator of neuron-glia interactions, forming a complex with Shg, Wrapper and Neurexin IV, the homolog of vertebrate Caspr/paranodin. Our results also support additional functions of Cno, independent of adherens junctions, as a regulator of adhesion and signaling events in non-epithelial tissues.
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Affiliation(s)
- Jana Slováková
- Instituto de Neurociencias de Alicante, CSIC/UMH, Sant Joan d'Alacant, Alicante, Spain
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Yu YV, Li Z, Rizzo NP, Einstein J, Welte MA. Targeting the motor regulator Klar to lipid droplets. BMC Cell Biol 2011; 12:9. [PMID: 21349165 PMCID: PMC3051913 DOI: 10.1186/1471-2121-12-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 02/24/2011] [Indexed: 11/24/2022] Open
Abstract
Background In Drosophila, the transport regulator Klar displays tissue-specific localization: In photoreceptors, it is abundant on the nuclear envelope; in early embryos, it is absent from nuclei, but instead present on lipid droplets. Differential targeting of Klar appears to be due to isoform variation. Droplet targeting, in particular, has been suggested to occur via a variant C-terminal region, the LD domain. Although the LD domain is necessary and sufficient for droplet targeting in cultured cells, lack of specific reagents had made it previously impossible to analyze its role in vivo. Results Here we describe a new mutant allele of klar with a lesion specifically in the LD domain; this lesion abolishes both droplet localization of Klar and the ability of Klar to regulate droplet motion. It does not disrupt Klar's function for nuclear migration in photoreceptors. Using a GFP-LD fusion, we show that the LD domain is not only necessary but also sufficient for droplet targeting in vivo; it mediates droplet targeting in embryos, in ovaries, and in a number of somatic tissues. Conclusions Our analysis demonstrates that droplet targeting of Klar occurs via a cis-acting sequence and generates a new tool for monitoring lipid droplets in living tissues of Drosophila.
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Affiliation(s)
- Yanxun V Yu
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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38
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Watson JD, Wheeler SR, Stagg SB, Crews ST. Drosophila hedgehog signaling and engrailed-runt mutual repression direct midline glia to alternative ensheathing and non-ensheathing fates. Development 2011; 138:1285-95. [PMID: 21350018 DOI: 10.1242/dev.056895] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Drosophila CNS contains a variety of glia, including highly specialized glia that reside at the CNS midline and functionally resemble the midline floor plate glia of the vertebrate spinal cord. Both insect and vertebrate midline glia play important roles in ensheathing axons that cross the midline and secreting signals that control a variety of developmental processes. The Drosophila midline glia consist of two spatially and functionally distinct populations. The anterior midline glia (AMG) are ensheathing glia that migrate, surround and send processes into the axon commissures. By contrast, the posterior midline glia (PMG) are non-ensheathing glia. Together, the Notch and hedgehog signaling pathways generate AMG and PMG from midline neural precursors. Notch signaling is required for midline glial formation and for transcription of a core set of midline glial-expressed genes. The Hedgehog morphogen is secreted from ectodermal cells adjacent to the CNS midline and directs a subset of midline glia to become PMG. Two transcription factor genes, runt and engrailed, play important roles in AMG and PMG development. The runt gene is expressed in AMG, represses engrailed and maintains AMG gene expression. The engrailed gene is expressed in PMG, represses runt and maintains PMG gene expression. In addition, engrailed can direct midline glia to a PMG-like non-ensheathing fate. Thus, two signaling pathways and runt-engrailed mutual repression initiate and maintain two distinct populations of midline glia that differ functionally in gene expression, glial migration, axon ensheathment, process extension and patterns of apoptosis.
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Affiliation(s)
- Joseph D Watson
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
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Morozova T, Hackett J, Sedaghat Y, Sonnenfeld M. The Drosophila jing gene is a downstream target in the Trachealess/Tango tracheal pathway. Dev Genes Evol 2010; 220:191-206. [PMID: 21061019 DOI: 10.1007/s00427-010-0339-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 10/08/2010] [Indexed: 11/28/2022]
Abstract
Primary branching in the Drosophila trachea is regulated by the Trachealess (Trh) and Tango (Tgo) basic helix-loop-helix-PAS (bHLH-PAS) heterodimers, the POU protein Drifter (Dfr)/Ventral Veinless (Vvl), and the Pointed (Pnt) ETS transcription factor. The jing gene encodes a zinc finger protein also required for tracheal development. Three Trh/Tgo DNA-binding sites, known as CNS midline elements, in 1.5 kb of jing 5′ cis-regulatory sequence (jing1.5) previously suggested a downstream role for jing in the pathway. Here, we show that jing is a direct downstream target of Trh/Tgo and that Vvl and Pnt are also involved in jing tracheal activation. In vivo lacZ enhancer detection assays were used to identify cis-regulatory elements mediating embryonic expression patterns of jing. A 2.8-kb jing enhancer (jing2.8) drove lacZ expression in all tracheal cell lineages, the CNS midline and Engrailed-positive segmental stripes, mimicking endogenous jing expression. A 1.3-kb element within jing2.8 drove expression that was restricted to Engrailed-positive CNS midline cells and segmental ectodermal stripes. Surprisingly, jing1.5-lacZ expression was restricted to tracheal fusion cells despite the presence of consensus DNA-binding sites for bHLH-PAS, ETS, and POU domain transcription factors. Given the absence of Trh/Tgo DNA-binding sites in the jing1.3 enhancer, these results are consistent with previous observations suggesting a combinatorial basis to Trh-/Tgo-mediated transcriptional regulation in the trachea.
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Affiliation(s)
- Tatiana Morozova
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
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Fulkerson E, Estes PA. Common motifs shared by conserved enhancers of Drosophila midline glial genes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2010; 316:61-75. [PMID: 21154525 DOI: 10.1002/jez.b.21382] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 09/07/2010] [Accepted: 09/28/2010] [Indexed: 12/12/2022]
Abstract
Coding sequences are usually the most highly conserved sectors of DNA, but genomic regions controlling the expression pattern of certain genes can also be conserved across diverse species. In this study, we identify five enhancers capable of activating transcription in the midline glia of Drosophila melanogaster and each contains sequences conserved across at least 11 Drosophila species. In addition, the conserved sequences contain reiterated motifs for binding sites of the known midline transcriptional activators, Single-minded, Tango, Dichaete, and Pointed. To understand the molecular basis for the highly conserved genomic subregions within enhancers of the midline genes, we tested the ability of various motifs to affect midline expression, both individually and in combination, within synthetic reporter constructs. Multiple copies of the binding site for the midline regulators Single-minded and Tango can drive expression in midline cells; however, small changes to the sequences flanking this transcription factor binding site can inactivate expression in midline cells and activate expression in tracheal cells instead. For the midline genes described in this study, the highly conserved sequences appear to juxtapose positive and negative regulatory factors in a configuration that activates genes specifically in the midline glia, while maintaining them inactive in other tissues, including midline neurons and tracheal cells.
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Affiliation(s)
- Eric Fulkerson
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695, USA
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41
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Ruiz S, Rickert C, Berger C, Technau GM, Cantera R. Spatio-temporal pattern of cells expressing the clock genes period and timeless and the lineages of period expressing neurons in the embryonic CNS of Drosophila melanogaster. Gene Expr Patterns 2010; 10:274-82. [DOI: 10.1016/j.gep.2010.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 05/31/2010] [Accepted: 06/04/2010] [Indexed: 11/26/2022]
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Djiane A, Mlodzik M. The Drosophila GIPC homologue can modulate myosin based processes and planar cell polarity but is not essential for development. PLoS One 2010; 5:e11228. [PMID: 20574526 PMCID: PMC2888583 DOI: 10.1371/journal.pone.0011228] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 06/01/2010] [Indexed: 01/20/2023] Open
Abstract
Epithelia often show, in addition to the ubiquitous apico-basal (A/B) axis, a polarization within the plane of the epithelium, perpendicular to the A/B axis. Such planar cell polarity (PCP) is for example evident in the regular arrangement of the stereocilia in the cochlea of the mammalian inner ear or in (almost) all Drosophila adult external structures. GIPCs (GAIP interacting protein, C terminus) were first identified in mammals and bind to the Gαi GTPase activating protein RGS-GAIP. They have been proposed to act in a G-protein coupled complex controlling vesicular trafficking. Although GIPCs have been found to bind to numerous proteins including Frizzled receptors, which participate in PCP establishment, there is little in vivo evidence for the functional role(s) of GIPCs. We show here that overexpressed Drosophila dGIPC alters PCP generation in the wing. We were however unable to find any binding between dGIPC and the Drosophila receptors Fz1 and Fz2. The effect of overexpressed dGIPC is likely due to an effect on the actin cytoskeleton via myosins, since it is almost entirely suppressed by removing a genomic copy of the Myosin VI/jaguar gene. Surprisingly, although dGIPC can interfere with PCP generation and myosin based processes, the complete loss-of-function of dGIPC gives viable adults with no PCP or other detectable defects arguing for a non-essential role of dGIPC in viability and normal Drosophila development.
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Affiliation(s)
- Alexandre Djiane
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Marek Mlodzik
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
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Ivankova N, Tretyakova I, Lyozin GT, Avanesyan E, Zolotukhin A, Zatsepina OG, Evgen'ev MB, Mamon LA. Alternative transcripts expressed by small bristles, the Drosophila melanogaster nxf1 gene. Gene 2010; 458:11-9. [DOI: 10.1016/j.gene.2010.02.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 02/16/2010] [Accepted: 02/25/2010] [Indexed: 11/30/2022]
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DMob4/Phocein regulates synapse formation, axonal transport, and microtubule organization. J Neurosci 2010; 30:5189-203. [PMID: 20392941 DOI: 10.1523/jneurosci.5823-09.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The monopolar spindle-one-binder (Mob) family of kinase-interacting proteins regulate cell cycle and cell morphology, and their dysfunction has been linked to cancer. Models for Mob function are primarily based on studies of Mob1 and Mob2 family members in yeast. In contrast, the function of the highly conserved metazoan Phocein/Mob3 subfamily is unknown. We identified the Drosophila Phocein homolog (DMob4) as a regulator of neurite branching in a genome-wide RNA interference screen for neuronal morphology mutants. To further characterize DMob4, we generated null and hypomorphic alleles and performed in vivo cell biological and physiological analysis. We find that DMob4 plays a prominent role in neural function, regulating axonal transport, membrane excitability, and organization of microtubule networks. DMob4 mutant neuromuscular synapses also show a profound overgrowth of synaptic boutons, similar to known Drosophila endocytotic mutants. DMob4 and human Phocein are >80% identical, and the lethality of DMob4 mutants can be rescued by a human phocein transgene, indicating a conservation of function across evolution. These findings suggest a novel role for Phocein proteins in the regulation of axonal transport, neurite elongation, synapse formation, and microtubule organization.
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Abstract
The glia that reside at the midline of the Drosophila CNS are an important embryonic signaling center and also wrap the axons that cross the CNS. The development of the midline glia (MG) is characterized by migration, ensheathment, subdivision of axon commissures, apoptosis, and the extension of glial processes. All of these events are characterized by cell-cell contact between MG and adjacent neurons. Cell adhesion and signaling proteins that mediate different aspects of MG development and MG-neuron interactions have been identified. This provides a foundation for ultimately obtaining an integrated picture of how the MG assemble into a characteristic axonal support structure in the CNS.
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Affiliation(s)
- Stephen T Crews
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Wheeler SR, Stagg SB, Crews ST. MidExDB: a database of Drosophila CNS midline cell gene expression. BMC DEVELOPMENTAL BIOLOGY 2009; 9:56. [PMID: 19903351 PMCID: PMC2777870 DOI: 10.1186/1471-213x-9-56] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 11/10/2009] [Indexed: 05/25/2023]
Abstract
Background The Drosophila CNS midline cells are an excellent model system to study neuronal and glial development because of their diversity of cell types and the relative ease in identifying and studying the function of midline-expressed genes. In situ hybridization experiments generated a large dataset of midline gene expression patterns. To help synthesize these data and make them available to the scientific community, we developed a web-accessible database. Description MidExDB (Drosophila CNS Midline Gene Expression Database) is comprised of images and data from our in situ hybridization experiments that examined midline gene expression. Multiple search tools are available to allow each type of data to be viewed and compared. Descriptions of each midline cell type and their development are included as background information. Conclusion MidExDB integrates large-scale gene expression data with the ability to identify individual cell types providing the foundation for detailed genetic, molecular, and biochemical studies of CNS midline cell neuronal and glial development and function. This information has general relevance for the study of nervous system development in other organisms, and also provides insight into transcriptional regulation.
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Affiliation(s)
- Scott R Wheeler
- Program in Molecular Biology and Biophysics, Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.
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Lüer K, Technau GM. Single cell cultures of Drosophila neuroectodermal and mesectodermal central nervous system progenitors reveal different degrees of developmental autonomy. Neural Dev 2009; 4:30. [PMID: 19650920 PMCID: PMC2736940 DOI: 10.1186/1749-8104-4-30] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 08/03/2009] [Indexed: 11/10/2022] Open
Abstract
Background The Drosophila embryonic central nervous system (CNS) develops from two sets of progenitor cells, neuroblasts and ventral midline progenitors, which behave differently in many respects. Neuroblasts derive from the neurogenic region of the ectoderm and form the lateral parts of the CNS. Ventral midline precursors are formed by two rows of mesectodermal cells and build the CNS midline. There is plenty of evidence that individual identities are conferred to precursor cells by positional information in the ectoderm. It is unclear, however, how far the precursors can maintain their identities and developmental properties in the absence of normal external signals. Results To separate the respective contributions of autonomous properties versus extrinsic signals during their further development, we isolated individual midline precursors and neuroectodermal precursors at the pre-mitotic gastrula stage, traced their development in vitro, and analyzed the characteristics of their lineages in comparison with those described for the embryo. Although individually cultured mesectodermal cells exhibit basic characteristics of CNS midline progenitors, the clones produced by these progenitors differ from their in situ counterparts with regard to cell numbers, expression of molecular markers, and the separation of neuronal and glial fate. In contrast, clones derived from individually cultured precursors taken from specific dorsoventral zones of the neuroectoderm develop striking similarities to the lineages of neuroblasts that normally delaminate from these zones and develop in situ. Conclusion This in vitro analysis allows for the first time a comparison of the developmental capacities in situ and in vitro of individual neural precursors of defined spatial and temporal origin. The data reveal that cells isolated at the pre-mitotic and pre-delamination stage express characteristics of the progenitor type appropriate to their site of origin in the embryo. However, presumptive neuroblasts, once specified in the neuroectoderm, exhibit a higher degree of autonomy regarding generation of their lineages compared to mesectodermal midline progenitors.
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Affiliation(s)
- Karin Lüer
- Institute of Genetics, University of Mainz, Germany.
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Wheeler SR, Banerjee S, Blauth K, Rogers SL, Bhat MA, Crews ST. Neurexin IV and Wrapper interactions mediate Drosophila midline glial migration and axonal ensheathment. Development 2009; 136:1147-57. [PMID: 19270173 DOI: 10.1242/dev.030254] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glia play crucial roles in ensheathing axons, a process that requires an intricate series of glia-neuron interactions. The membrane-anchored protein Wrapper is present in Drosophila midline glia and is required for ensheathment of commissural axons. By contrast, Neurexin IV is present on the membranes of neurons and commissural axons, and is highly concentrated at their interfaces with midline glia. Analysis of Neurexin IV and wrapper mutant embryos revealed identical defects in glial migration, ensheathment and glial subdivision of the commissures. Mutant and misexpression experiments indicated that Neurexin IV membrane localization is dependent on interactions with Wrapper. Cell culture aggregation assays and biochemical experiments demonstrated the ability of Neurexin IV to promote cell adhesion by binding to Wrapper. These results show that neuronal-expressed Neurexin IV and midline glial-expressed Wrapper act as heterophilic adhesion molecules that mediate multiple cellular events involved in glia-neuron interactions.
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Affiliation(s)
- Scott R Wheeler
- Department of Biochemistry and Biophysics, The University of North Carolina, Chapel Hill, NC 27599, USA
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Hofmann A, Brünner M, Korge G. The winged-helix transcription factor JUMU is a haplo-suppressor/triplo-enhancer of PEV in various tissues but exhibits reverse PEV effects in the brain of Drosophila melanogaster. Chromosome Res 2009; 17:347-58. [DOI: 10.1007/s10577-009-9026-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 12/02/2008] [Accepted: 12/02/2008] [Indexed: 11/28/2022]
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Stork T, Thomas S, Rodrigues F, Silies M, Naffin E, Wenderdel S, Klämbt C. Drosophila Neurexin IV stabilizes neuron-glia interactions at the CNS midline by binding to Wrapper. Development 2009; 136:1251-61. [PMID: 19261699 DOI: 10.1242/dev.032847] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ensheathment of axons by glial membranes is a key feature of complex nervous systems ensuring the separation of single axons or axonal fascicles. Nevertheless, the molecules that mediate the recognition and specific adhesion of glial and axonal membranes are largely unknown. We use the Drosophila midline of the embryonic central nervous system as a model to investigate these neuron glia interactions. During development, the midline glial cells acquire close contact to commissural axons and eventually extend processes into the commissures to wrap individual axon fascicles. Here, we show that this wrapping of axons depends on the interaction of the neuronal transmembrane protein Neurexin IV with the glial Ig-domain protein Wrapper. Although Neurexin IV has been previously described to be an essential component of epithelial septate junctions (SJ), we show that its function in mediating glial wrapping at the CNS midline is independent of SJ formation. Moreover, differential splicing generates two different Neurexin IV isoforms. One mRNA is enriched in septate junction-forming tissues, whereas the other mRNA is expressed by neurons and recruited to the midline by Wrapper. Although both Neurexin IV isoforms are able to bind Wrapper, the neuronal isoform has a higher affinity for Wrapper. We conclude that Neurexin IV can mediate different adhesive cell-cell contacts depending on the isoforms expressed and the context of its interaction partners.
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Affiliation(s)
- Tobias Stork
- Institut für Neurobiologie, Universität Münster, Badestrasse 9, D-48149 Münster, Germany
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