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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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Liu T, Zhang T, Nicolas M, Boussicault L, Rice H, Soldano A, Claeys A, Petrova I, Fradkin L, De Strooper B, Potier MC, Hassan BA. The amyloid precursor protein is a conserved Wnt receptor. eLife 2021; 10:69199. [PMID: 34515635 PMCID: PMC8437438 DOI: 10.7554/elife.69199] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/01/2021] [Indexed: 12/31/2022] Open
Abstract
The Amyloid Precursor Protein (APP) and its homologues are transmembrane proteins required for various aspects of neuronal development and activity, whose molecular function is unknown. Specifically, it is unclear whether APP acts as a receptor, and if so what its ligand(s) may be. We show that APP binds the Wnt ligands Wnt3a and Wnt5a and that this binding regulates APP protein levels. Wnt3a binding promotes full-length APP (flAPP) recycling and stability. In contrast, Wnt5a promotes APP targeting to lysosomal compartments and reduces flAPP levels. A conserved Cysteine-Rich Domain (CRD) in the extracellular portion of APP is required for Wnt binding, and deletion of the CRD abrogates the effects of Wnts on flAPP levels and trafficking. Finally, loss of APP results in increased axonal and reduced dendritic growth of mouse embryonic primary cortical neurons. This phenotype can be cell-autonomously rescued by full length, but not CRD-deleted, APP and regulated by Wnt ligands in a CRD-dependent manner.
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Affiliation(s)
- Tengyuan Liu
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France.,Doctoral School of Biomedical Sciences, Leuven, Belgium
| | - Tingting Zhang
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France.,Doctoral School of Biomedical Sciences, Leuven, Belgium
| | - Maya Nicolas
- Doctoral School of Biomedical Sciences, Leuven, Belgium.,Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Lydie Boussicault
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
| | - Heather Rice
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Alessia Soldano
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Annelies Claeys
- Center for Brain and Disease, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Iveta Petrova
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Lee Fradkin
- Laboratory of Developmental Neurobiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Bart De Strooper
- Center for Brain and Disease, Leuven, Belgium.,UK Dementia Research institute at University College London, London, United Kingdom
| | - Marie-Claude Potier
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
| | - Bassem A Hassan
- Paris Brain Institute - Institut du Cerveau, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, Paris, France
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3
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Hing H, Reger N, Snyder J, Fradkin LG. Interplay between axonal Wnt5-Vang and dendritic Wnt5-Drl/Ryk signaling controls glomerular patterning in the Drosophila antennal lobe. PLoS Genet 2020; 16:e1008767. [PMID: 32357156 PMCID: PMC7219789 DOI: 10.1371/journal.pgen.1008767] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 05/13/2020] [Accepted: 04/08/2020] [Indexed: 12/14/2022] Open
Abstract
Despite the importance of dendritic targeting in neural circuit assembly, the mechanisms by which it is controlled still remain incompletely understood. We previously showed that in the developing Drosophila antennal lobe, the Wnt5 protein forms a gradient that directs the ~45˚ rotation of a cluster of projection neuron (PN) dendrites, including the adjacent DA1 and VA1d dendrites. We report here that the Van Gogh (Vang) transmembrane planar cell polarity (PCP) protein is required for the rotation of the DA1/VA1d dendritic pair. Cell type-specific rescue and mosaic analyses showed that Vang functions in the olfactory receptor neurons (ORNs), suggesting a codependence of ORN axonal and PN dendritic targeting. Loss of Vang suppressed the repulsion of the VA1d dendrites by Wnt5, indicating that Wnt5 signals through Vang to direct the rotation of the DA1 and VA1d glomeruli. We observed that the Derailed (Drl)/Ryk atypical receptor tyrosine kinase is also required for the rotation of the DA1/VA1d dendritic pair. Antibody staining showed that Drl/Ryk is much more highly expressed by the DA1 dendrites than the adjacent VA1d dendrites. Mosaic and epistatic analyses showed that Drl/Ryk specifically functions in the DA1 dendrites in which it antagonizes the Wnt5-Vang repulsion and mediates the migration of the DA1 glomerulus towards Wnt5. Thus, the nascent DA1 and VA1d glomeruli appear to exhibit Drl/Ryk-dependent biphasic responses to Wnt5. Our work shows that the final patterning of the fly olfactory map is the result of an interplay between ORN axons and PN dendrites, wherein converging pre- and postsynaptic processes contribute key Wnt5 signaling components, allowing Wnt5 to orient the rotation of nascent synapses through a PCP mechanism. During brain development, the processes of nerve cells, axons and dendrites, grow over long distances to find and connect with each other to form synapses in precise locations. Understanding the mechanisms that control the growth of these neurites is important for understanding normal brain functions like neuronal plasticity and neural diseases like autism. Although much progress has been made by studying the development of axons and dendrites separately, the mechanisms that guide neuronal processes to their final locations are still incompletely understood. In particular, careful observation of converging pre- and postsynaptic processes suggests that their targeting may be coordinated. Whether the final targeting of axons and dendrites are functionally linked and what molecular mechanisms may be involved are unknown. In this paper we show that, in the developing Drosophila olfactory circuit, coalescing axons and dendrites respond to the extracellular Wnt5 signal in a codependent manner. We demonstrate that the converging axons and dendrites contribute different signaling components to the Wnt5 pathway, the Vang Gogh and Derailed transmembrane receptors respectively, which allow Wnt5 to coordinately guide the targeting of the neurites. Our work thus reveals a novel mechanism of neural circuit patterning and the molecular mechanism that controls it.
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Affiliation(s)
- Huey Hing
- Department of Biology, State University of New York at Brockport, Brockport, NY, United States of America
- * E-mail:
| | - Noah Reger
- Department of Biology, State University of New York at Brockport, Brockport, NY, United States of America
| | - Jennifer Snyder
- Department of Biology, State University of New York at Brockport, Brockport, NY, United States of America
| | - Lee G. Fradkin
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, United States of America
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4
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Amourda C, Saunders TE. The mirtron miR-1010 functions in concert with its host gene SKIP to balance elevation of nAcRβ2. Sci Rep 2020; 10:1688. [PMID: 32015391 PMCID: PMC6997181 DOI: 10.1038/s41598-020-58655-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 01/19/2020] [Indexed: 02/02/2023] Open
Abstract
Mirtrons are non-canonical miRNAs arising by splicing and debranching from short introns. A plethora of introns have been inferred by computational analyses as potential mirtrons. Yet, few have been experimentally validated and their functions, particularly in relation to their host genes, remain poorly understood. Here, we found that Drosophila larvae lacking either the mirtron miR-1010 or its binding site in the nicotinic acetylcholine receptor β2 (nAcRβ2) 3′UTR fail to grow properly and pupariate. Increase of cortical nAcRβ2 mediated by neural activity elevates the level of intracellular Ca2+, which in turn activates CaMKII and, further downstream, the transcription factor Adf-1. We show that miR-1010 downregulates nAcRβ2. We reveal that Adf-1 initiates the expression of SKIP, the host gene of miR-1010. Preventing synaptic potentials from overshooting their optimal range requires both SKIP to temper synaptic potentials (incoherent feedforward loop) and miR-1010 to reduce nAcRβ2 mRNA levels (negative feedback loop). Our results demonstrate how a mirtron, in coordination with its host gene, contributes to maintaining appropriate receptor levels, which in turn may play a role in maintaining homeostasis.
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Affiliation(s)
- Christopher Amourda
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore. .,MRC London Institute of Medical Science, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
| | - Timothy E Saunders
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore. .,Department of Biological Sciences, National University of Singapore, Singapore, Singapore. .,Institute of Molecular and Cell Biology, A*Star, Proteos, Singapore.
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5
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Marmor-Kollet N, Gutman I, Issman-Zecharya N, Schuldiner O. Glial Derived TGF-β Instructs Axon Midline Stopping. Front Mol Neurosci 2019; 12:232. [PMID: 31611773 PMCID: PMC6776989 DOI: 10.3389/fnmol.2019.00232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 09/11/2019] [Indexed: 11/13/2022] Open
Abstract
A fundamental question that underlies the proper wiring and function of the nervous system is how axon extension stops during development. However, our mechanistic understanding of axon stopping is currently poor. The stereotypic development of the Drosophila mushroom body (MB) provides a unique system in which three types of anatomically distinct neurons (γ, α’/β’, and α/β) develop and interact to form a complex neuronal structure. All three neuronal types innervate the ipsi-lateral side and do not cross the midline. Here we find that Plum, an immunoglobulin (Ig) superfamily protein that we have previously shown to function as a TGF-β accessory receptor, is required within MB α/β neurons for their midline stopping. Overexpression of Plum within MB neurons is sufficient to induce retraction of α/β axons. As expected, rescue experiments revealed that Plum likely functions in α/β neurons and mediates midline stopping via the downstream effector RhoGEF2. Finally, we have identified glial-derived Myoglianin (Myo) as the major TGF-β ligand that instructs midline stopping of MB neurons. Taken together, our study strongly suggests that TGF-β signals originating from the midline facilitate midline stopping of α/β neuron in a Plum dependent manner.
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Affiliation(s)
- Neta Marmor-Kollet
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Itai Gutman
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Noa Issman-Zecharya
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Oren Schuldiner
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
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6
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Roy JP, Halford MM, Stacker SA. The biochemistry, signalling and disease relevance of RYK and other WNT-binding receptor tyrosine kinases. Growth Factors 2018; 36:15-40. [PMID: 29806777 DOI: 10.1080/08977194.2018.1472089] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The receptor tyrosine kinases (RTKs) are a well-characterized family of growth factor receptors that have central roles in human disease and are frequently therapeutically targeted. The RYK, ROR, PTK7 and MuSK subfamilies make up an understudied subset of WNT-binding RTKs. Numerous developmental, stem cell and pathological roles of WNTs, in particular WNT5A, involve signalling via these WNT receptors. The WNT-binding RTKs have highly context-dependent signalling outputs and stimulate the β-catenin-dependent, planar cell polarity and/or WNT/Ca2+ pathways. RYK, ROR and PTK7 members have a pseudokinase domain in their intracellular regions. Alternative signalling mechanisms, including proteolytic cleavage and protein scaffolding functions, have been identified for these receptors. This review explores the structure, signalling, physiological and pathological roles of RYK, with particular attention paid to cancer and the possibility of therapeutically targeting RYK. The other WNT-binding RTKs are compared with RYK throughout to highlight the similarities and differences within this subset of WNT receptors.
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Affiliation(s)
- James P Roy
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
- b Sir Peter MacCallum Department of Oncology , The University of Melbourne , Parkville , Australia
| | - Michael M Halford
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
| | - Steven A Stacker
- a Tumour Angiogenesis and Microenvironment Program , Peter MacCallum Cancer Centre , Melbourne , Australia
- b Sir Peter MacCallum Department of Oncology , The University of Melbourne , Parkville , Australia
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7
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Oliva C, Hassan BA. Receptor Tyrosine Kinases and Phosphatases in Neuronal Wiring: Insights From Drosophila. Curr Top Dev Biol 2016; 123:399-432. [PMID: 28236973 DOI: 10.1016/bs.ctdb.2016.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Tyrosine phosphorylation is at the crossroads of many signaling pathways. Brain wiring is not an exception, and several receptor tyrosine kinases (RTKs) and tyrosine receptor phosphates (RPTPs) have been involved in this process. Considerable work has been done on RTKs, and for many of them, detailed molecular mechanisms and functions in several systems have been characterized. In contrast, RPTPs have been studied considerably less and little is known about their ligands and substrates. In both families, we find redundancy between different members to accomplish particular wiring patterns. Strikingly, some RTKs and RPTPs have lost their catalytic activity during evolution, but not their importance in biological processes. In this regard, we have to keep in mind that these proteins have multiple domains and some of their functions are independent of tyrosine phosphorylation/dephosphorylation. Since RTKs and RPTPs are enzymes involved not only in early stages of axon and dendrite pathfinding but also in synapse formation and physiology, they have a potential as drug targets. Drosophila has been a key model organism in the search of a better understanding of brain wiring, and its sophisticated toolbox is very suitable for studying the function of genes with pleiotropic functions such as RTKs and RPTPs, from wiring to synaptic formation and function. In these review, we mainly cover findings from this model organism and complement them with discoveries in vertebrate systems.
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Affiliation(s)
- Carlos Oliva
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad of Chile, Santiago, Chile.
| | - Bassem A Hassan
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, AP-HP, Institut du Cerveau et la Moelle (ICM)-Hôpital Pitié-Salpêtrière, Boulevard de l'Hôpital, Paris, France.
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8
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The Formin DAAM Functions as Molecular Effector of the Planar Cell Polarity Pathway during Axonal Development in Drosophila. J Neurosci 2015; 35:10154-67. [PMID: 26180192 DOI: 10.1523/jneurosci.3708-14.2015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent studies established that the planar cell polarity (PCP) pathway is critical for various aspects of nervous system development and function, including axonal guidance. Although it seems clear that PCP signaling regulates actin dynamics, the mechanisms through which this occurs remain elusive. Here, we establish a functional link between the PCP system and one specific actin regulator, the formin DAAM, which has previously been shown to be required for embryonic axonal morphogenesis and filopodia formation in the growth cone. We show that dDAAM also plays a pivotal role during axonal growth and guidance in the adult Drosophila mushroom body, a brain center for learning and memory. By using a combination of genetic and biochemical assays, we demonstrate that Wnt5 and the PCP signaling proteins Frizzled, Strabismus, and Dishevelled act in concert with the small GTPase Rac1 to activate the actin assembly functions of dDAAM essential for correct targeting of mushroom body axons. Collectively, these data suggest that dDAAM is used as a major molecular effector of the PCP guidance pathway. By uncovering a signaling system from the Wnt5 guidance cue to an actin assembly factor, we propose that the Wnt5/PCP navigation system is linked by dDAAM to the regulation of the growth cone actin cytoskeleton, and thereby growth cone behavior, in a direct way.
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9
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Siegenthaler D, Enneking EM, Moreno E, Pielage J. L1CAM/Neuroglian controls the axon-axon interactions establishing layered and lobular mushroom body architecture. ACTA ACUST UNITED AC 2015; 208:1003-18. [PMID: 25825519 PMCID: PMC4384726 DOI: 10.1083/jcb.201407131] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The establishment of neuronal circuits depends on the guidance of axons both along and in between axonal populations of different identity; however, the molecular principles controlling axon-axon interactions in vivo remain largely elusive. We demonstrate that the Drosophila melanogaster L1CAM homologue Neuroglian mediates adhesion between functionally distinct mushroom body axon populations to enforce and control appropriate projections into distinct axonal layers and lobes essential for olfactory learning and memory. We addressed the regulatory mechanisms controlling homophilic Neuroglian-mediated cell adhesion by analyzing targeted mutations of extra- and intracellular Neuroglian domains in combination with cell type-specific rescue assays in vivo. We demonstrate independent and cooperative domain requirements: intercalating growth depends on homophilic adhesion mediated by extracellular Ig domains. For functional cluster formation, intracellular Ankyrin2 association is sufficient on one side of the trans-axonal complex whereas Moesin association is likely required simultaneously in both interacting axonal populations. Together, our results provide novel mechanistic insights into cell adhesion molecule-mediated axon-axon interactions that enable precise assembly of complex neuronal circuits.
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Affiliation(s)
- Dominique Siegenthaler
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland University of Basel, 4003 Basel, Switzerland
| | - Eva-Maria Enneking
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland University of Basel, 4003 Basel, Switzerland
| | - Eliza Moreno
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Jan Pielage
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
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10
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The E3 ligase ube3a is required for learning in Drosophila melanogaster. Biochem Biophys Res Commun 2015; 462:71-7. [DOI: 10.1016/j.bbrc.2015.04.110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 04/12/2015] [Indexed: 11/18/2022]
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11
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Kelly SM, Bienkowski R, Banerjee A, Melicharek DJ, Brewer ZA, Marenda DR, Corbett AH, Moberg KH. The Drosophila ortholog of the Zc3h14 RNA binding protein acts within neurons to pattern axon projection in the developing brain. Dev Neurobiol 2015; 76:93-106. [PMID: 25980665 DOI: 10.1002/dneu.22301] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 12/18/2022]
Abstract
The dNab2 polyadenosine RNA binding protein is the D. melanogaster ortholog of the vertebrate ZC3H14 protein, which is lost in a form of inherited intellectual disability (ID). Human ZC3H14 can rescue D. melanogaster dNab2 mutant phenotypes when expressed in all neurons of the developing nervous system, suggesting that dNab2/ZC3H14 performs well-conserved roles in neurons. However, the cellular and molecular requirements for dNab2/ZC3H14 in the developing nervous system have not been defined in any organism. Here we show that dNab2 is autonomously required within neurons to pattern axon projection from Kenyon neurons into the mushroom bodies, which are required for associative olfactory learning and memory in insects. Mushroom body axons lacking dNab2 project aberrantly across the brain midline and also show evidence of defective branching. Coupled with the prior finding that ZC3H14 is highly expressed in rodent hippocampal neurons, this requirement for dNab2 in mushroom body neurons suggests that dNab2/ZC3H14 has a conserved role in supporting axon projection and branching. Consistent with this idea, loss of dNab2 impairs short-term memory in a courtship conditioning assay. Taken together these results reveal a cell-autonomous requirement for the dNab2 RNA binding protein in mushroom body development and provide a window into potential neurodevelopmental functions of the human ZC3H14 protein.
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Affiliation(s)
- Seth M Kelly
- Department of Biology, College of Wooster, Wooster, Ohio, 44691
| | - Rick Bienkowski
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322.,Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322.,Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia, 30322
| | - Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - David J Melicharek
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | | | - Daniel R Marenda
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104.,Departments of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322
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12
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Reynaud E, Lahaye LL, Boulanger A, Petrova IM, Marquilly C, Flandre A, Martianez T, Privat M, Noordermeer JN, Fradkin LG, Dura JM. Guidance of Drosophila Mushroom Body Axons Depends upon DRL-Wnt Receptor Cleavage in the Brain Dorsomedial Lineage Precursors. Cell Rep 2015; 11:1293-304. [PMID: 25981040 DOI: 10.1016/j.celrep.2015.04.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 03/07/2015] [Accepted: 04/15/2015] [Indexed: 10/23/2022] Open
Abstract
In vivo axon pathfinding mechanisms in the neuron-dense brain remain relatively poorly characterized. We study the Drosophila mushroom body (MB) axons, whose α and β branches connect to different brain areas. We show that the Ryk family WNT5 receptor, DRL (derailed), which is expressed in the dorsomedial lineages, brain structure precursors adjacent to the MBs, is required for MB α branch axon guidance. DRL acts to capture and present WNT5 to MB axons rather than transduce a WNT5 signal. DRL's ectodomain must be cleaved and shed to guide α axons. DRL-2, another Ryk, is expressed within MB axons and functions as a repulsive WNT5 signaling receptor. Finally, our biochemical data support the existence of a ternary complex composed of the cleaved DRL ectodomain, WNT5, and DRL-2. Thus, the interaction of MB-extrinsic and -intrinsic Ryks via their common ligand acts to guide MB α axons.
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Affiliation(s)
- Elodie Reynaud
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Liza L Lahaye
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Ana Boulanger
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Iveta M Petrova
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Claire Marquilly
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Adrien Flandre
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Tania Martianez
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Martin Privat
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Jasprina N Noordermeer
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Lee G Fradkin
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands.
| | - Jean-Maurice Dura
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France.
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13
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unfulfilled interacting genes display branch-specific roles in the development of mushroom body axons in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2014; 4:693-706. [PMID: 24558265 PMCID: PMC4577660 DOI: 10.1534/g3.113.009829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The mushroom body (MB) of Drosophila melanogaster is an organized collection of interneurons that is required for learning and memory. Each of the three subtypes of MB neurons, γ, α´/β´, and α/β, branch at some point during their development, providing an excellent model in which to study the genetic regulation of axon branching. Given the sequential birth order and the unique patterning of MB neurons, it is likely that specific gene cascades are required for the different guidance events that form the characteristic lobes of the MB. The nuclear receptor UNFULFILLED (UNF), a transcription factor, is required for the differentiation of all MB neurons. We have developed and used a classical genetic suppressor screen that takes advantage of the fact that ectopic expression of unf causes lethality to identify candidate genes that act downstream of UNF. We hypothesized that reducing the copy number of unf-interacting genes will suppress the unf-induced lethality. We have identified 19 candidate genes that when mutated suppress the unf-induced lethality. To test whether candidate genes impact MB development, we performed a secondary phenotypic screen in which the morphologies of the MBs in animals heterozygous for unf and a specific candidate gene were analyzed. Medial MB lobes were thin, missing, or misguided dorsally in five double heterozygote combinations (;unf/+;axin/+, unf/+;Fps85D/+, ;unf/+;Tsc1/+, ;unf/+;Rheb/+, ;unf/+;msn/+). Dorsal MB lobes were missing in ;unf/+;DopR2/+ or misprojecting beyond the termination point in ;unf/+;Sytβ double heterozygotes. These data suggest that unf and unf-interacting genes play specific roles in axon development in a branch-specific manner.
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14
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Clark CEJ, Liu Y, Cooper HM. The Yin and Yang of Wnt/Ryk axon guidance in development and regeneration. SCIENCE CHINA-LIFE SCIENCES 2014; 57:366-71. [DOI: 10.1007/s11427-014-4640-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 02/24/2014] [Indexed: 11/28/2022]
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15
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Halford MM, Macheda ML, Parish CL, Takano EA, Fox S, Layton D, Nice E, Stacker SA. A fully human inhibitory monoclonal antibody to the Wnt receptor RYK. PLoS One 2013; 8:e75447. [PMID: 24058687 PMCID: PMC3776778 DOI: 10.1371/journal.pone.0075447] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 08/18/2013] [Indexed: 11/19/2022] Open
Abstract
RYK is an unusual member of the receptor tyrosine kinase (RTK) family that is classified as a putative pseudokinase. RYK regulates fundamental biological processes including cell differentiation, migration and target selection, axon outgrowth and pathfinding by transducing signals across the plasma membrane in response to the high affinity binding of Wnt family ligands to its extracellular Wnt inhibitory factor (WIF) domain. Here we report the generation and initial characterization of a fully human inhibitory monoclonal antibody to the human RYK WIF domain. From a naïve human single chain fragment variable (scFv) phage display library, we identified anti-RYK WIF domain–specific scFvs then screened for those that could compete with Wnt3a for binding. Production of a fully human IgG1κ from an inhibitory scFv yielded a monoclonal antibody that inhibits Wnt5a-responsive RYK function in a neurite outgrowth assay. This antibody will have immediate applications for modulating RYK function in a range of settings including development and adult homeostasis, with significant potential for therapeutic use in human pathologies.
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Affiliation(s)
- Michael M. Halford
- Tumour Angiogenesis Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
- Angiogenesis Laboratory, Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Maria L. Macheda
- Tumour Angiogenesis Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
- Angiogenesis Laboratory, Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Clare L. Parish
- Florey Neuroscience Institutes, Melbourne Brain Centre, The University of Melbourne, Parkville, Victoria, Australia
| | - Elena A. Takano
- Tumour Angiogenesis Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Stephen Fox
- Tumour Angiogenesis Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia
| | - Daniel Layton
- Monash Antibody Technologies Facility, Monash University, Clayton, Victoria, Australia
| | - Edouard Nice
- Monash Antibody Technologies Facility, Monash University, Clayton, Victoria, Australia
| | - Steven A. Stacker
- Tumour Angiogenesis Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
- Angiogenesis Laboratory, Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Parkville, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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16
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Homodimerization of the Wnt receptor DERAILED recruits the Src family kinase SRC64B. Mol Cell Biol 2013; 33:4116-27. [PMID: 23979591 DOI: 10.1128/mcb.00169-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ryk pseudokinase receptors act as important transducers of Wnt signals, particularly in the nervous system. Little is known, however, of their interactions at the cell surface. Here, we show that a Drosophila Ryk family member, DERAILED (DRL), forms cell surface homodimers and can also heterodimerize with the two other fly Ryks, DERAILED-2 and DOUGHNUT ON 2. DERAILED homodimerization levels increase significantly in the presence of its ligand, WNT5. In addition, DERAILED displays ligand-independent dimerization mediated by a motif in its transmembrane domain. Increased dimerization of DRL upon WNT5 binding or upon the replacement of DERAILED's extracellular domain with the immunoglobulin Fc domain results in an increased recruitment of the Src family kinase SRC64B, a previously identified downstream pathway effector. Formation of the SRC64B/DERAILED complex requires SRC64B's SH2 domain and DERAILED's PDZ-binding motif. Mutations in DERAILED's inactive tyrosine kinase-homologous domain also disrupt the formation of DERAILED/SRC64B complexes, indicating that its conformation is likely important in facilitating its interaction with SRC64B. Finally, we show that DERAILED's function during embryonic axon guidance requires its Wnt-binding domain, a putative juxtamembrane extracellular tetrabasic cleavage site, and the PDZ-binding domain, indicating that DERAILED's activation involves a complex set of events including both dimerization and proteolytic processing.
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17
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Abstract
Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases.
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Affiliation(s)
- Richelle Sopko
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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18
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Soldano A, Okray Z, Janovska P, Tmejová K, Reynaud E, Claeys A, Yan J, Atak ZK, De Strooper B, Dura JM, Bryja V, Hassan BA. The Drosophila homologue of the amyloid precursor protein is a conserved modulator of Wnt PCP signaling. PLoS Biol 2013; 11:e1001562. [PMID: 23690751 PMCID: PMC3653798 DOI: 10.1371/journal.pbio.1001562] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 04/02/2013] [Indexed: 01/23/2023] Open
Abstract
Wnt Planar Cell Polarity (PCP) signaling is a universal regulator of polarity in epithelial cells, but it regulates axon outgrowth in neurons, suggesting the existence of axonal modulators of Wnt-PCP activity. The Amyloid precursor proteins (APPs) are intensely investigated because of their link to Alzheimer's disease (AD). APP's in vivo function in the brain and the mechanisms underlying it remain unclear and controversial. Drosophila possesses a single APP homologue called APP Like, or APPL. APPL is expressed in all neurons throughout development, but has no established function in neuronal development. We therefore investigated the role of Drosophila APPL during brain development. We find that APPL is involved in the development of the Mushroom Body αβ neurons and, in particular, is required cell-autonomously for the β-axons and non-cell autonomously for the α-axons growth. Moreover, we find that APPL is a modulator of the Wnt-PCP pathway required for axonal outgrowth, but not cell polarity. Molecularly, both human APP and fly APPL form complexes with PCP receptors, thus suggesting that APPs are part of the membrane protein complex upstream of PCP signaling. Moreover, we show that APPL regulates PCP pathway activation by modulating the phosphorylation of the Wnt adaptor protein Dishevelled (Dsh) by Abelson kinase (Abl). Taken together our data suggest that APPL is the first example of a modulator of the Wnt-PCP pathway specifically required for axon outgrowth.
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Affiliation(s)
- Alessia Soldano
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Zeynep Okray
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Pavlina Janovska
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Kateřina Tmejová
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Elodie Reynaud
- Institut de Génétique Humaine/Centre National de la Recherche Scientifique UPR1142, Montpellier, France
- Laboratoire Neurogénétique et Mémoire, Département Génétique et Développement, Montpellier, France
| | - Annelies Claeys
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Jiekun Yan
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Zeynep Kalender Atak
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Bart De Strooper
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
| | - Jean-Maurice Dura
- Institut de Génétique Humaine/Centre National de la Recherche Scientifique UPR1142, Montpellier, France
- Laboratoire Neurogénétique et Mémoire, Département Génétique et Développement, Montpellier, France
| | - Vítězslav Bryja
- Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
- Institute of Biophysics of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Bassem A. Hassan
- VIB Center for the Biology of Disease, Leuven, Belgium
- Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
- Doctoral Program in Molecular and Developmental Genetics, University of Leuven Group Biomedicine, Leuven, Belgium
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19
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Kunz T, Kraft KF, Technau GM, Urbach R. Origin of Drosophila mushroom body neuroblasts and generation of divergent embryonic lineages. Development 2012; 139:2510-22. [DOI: 10.1242/dev.077883] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Key to understanding the mechanisms that underlie the specification of divergent cell types in the brain is knowledge about the neurectodermal origin and lineages of their stem cells. Here, we focus on the origin and embryonic development of the four neuroblasts (NBs) per hemisphere in Drosophila that give rise to the mushroom bodies (MBs), which are central brain structures essential for olfactory learning and memory. We show that these MBNBs originate from a single field of proneural gene expression within a specific mitotic domain of procephalic neuroectoderm, and that Notch signaling is not needed for their formation. Subsequently, each MBNB occupies a distinct position in the developing MB cortex and expresses a specific combination of transcription factors by which they are individually identifiable in the brain NB map. During embryonic development each MBNB generates an individual cell lineage comprising different numbers of neurons, including intrinsic γ-neurons and various types of non-intrinsic neurons that do not contribute to the MB neuropil. This contrasts with the postembryonic phase of MBNB development during which they have been shown to produce identical populations of intrinsic neurons. We show that different neuron types are produced in a lineage-specific temporal order and that neuron numbers are regulated by differential mitotic activity of the MBNBs. Finally, we demonstrate that γ-neuron axonal outgrowth and spatiotemporal innervation of the MB lobes follows a lineage-specific mode. The MBNBs are the first stem cells of the Drosophila CNS for which the origin and complete cell lineages have been determined.
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Affiliation(s)
- Thomas Kunz
- Institute of Genetics, University of Mainz, D-55099 Mainz, Germany
| | | | | | - Rolf Urbach
- Institute of Genetics, University of Mainz, D-55099 Mainz, Germany
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20
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Lahaye LL, Wouda RR, de Jong AWM, Fradkin LG, Noordermeer JN. WNT5 interacts with the Ryk receptors doughnut and derailed to mediate muscle attachment site selection in Drosophila melanogaster. PLoS One 2012; 7:e32297. [PMID: 22403643 PMCID: PMC3293800 DOI: 10.1371/journal.pone.0032297] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 01/24/2012] [Indexed: 01/12/2023] Open
Abstract
In recent years a number of the genes that regulate muscle formation and maintenance in higher organisms have been identified. Studies employing invertebrate and vertebrate model organisms have revealed that many of the genes required for early mesoderm specification are highly conserved throughout evolution. Less is known about the molecules that mediate the steps subsequent to myogenesis, e. g. myotube guidance and attachment to tendon cells. We use the stereotypic pattern of the Drosophila embryonic body wall musculature in genetic approaches to identify novel factors required for muscle attachment site selection. Here, we show that Wnt5 is needed in this process. The lateral transverse muscles frequently overshoot their target attachment sites and stably attach at novel epidermal sites in Wnt5 mutant embryos. Restoration of WNT5 expression in either the muscle or the tendon cell rescues the mutant phenotype. Surprisingly, the novel attachment sites in Wnt5 mutants frequently do not express the Stripe (SR) protein which has been shown to be required for terminal tendon cell differentiation. A muscle bypass phenotype was previously reported for embryos lacking the WNT5 receptor Derailed (DRL). drl and Wnt5 mutant embryos also exhibit axon path finding errors. DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins. We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype. Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection. These results extend previous findings that at least some of the molecular pathways that guide axons towards their targets are also employed for guidance of muscle fibers to their appropriate attachment sites.
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Affiliation(s)
| | | | | | - Lee G. Fradkin
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail: (JNN); (LGF)
| | - Jasprina N. Noordermeer
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail: (JNN); (LGF)
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21
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Homeobox gene distal-less is required for neuronal differentiation and neurite outgrowth in the Drosophila olfactory system. Proc Natl Acad Sci U S A 2012; 109:1578-83. [PMID: 22307614 DOI: 10.1073/pnas.1016741109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vertebrate Dlx genes have been implicated in the differentiation of multiple neuronal subtypes, including cortical GABAergic interneurons, and mutations in Dlx genes have been linked to clinical conditions such as epilepsy and autism. Here we show that the single Drosophila Dlx homolog, distal-less, is required both to specify chemosensory neurons and to regulate the morphologies of their axons and dendrites. We establish that distal-less is necessary for development of the mushroom body, a brain region that processes olfactory information. These are important examples of distal-less function in an invertebrate nervous system and demonstrate that the Drosophila larval olfactory system is a powerful model in which to understand distal-less functions during neurogenesis.
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22
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The Wnt5/planar cell polarity pathway regulates axonal development of the Drosophila mushroom body neuron. J Neurosci 2011; 31:4944-54. [PMID: 21451033 DOI: 10.1523/jneurosci.0154-11.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Axonal development is a fundamental process for circuit formation in the nervous system and is dependent on many cellular events, including axon initiation, elongation, guidance, and branching. The molecular mechanisms underlying these events have been well studied, especially for axon guidance. In the presence of a guidance cue, the polarization of a growth cone precedes the turning response, which is one example of the diverse forms of cell polarity. Planar cell polarity (PCP) is another example of cell polarity. Although some PCP genes are required for axonal tract formation in vertebrates, it remains elusive whether these genes participate in a common PCP pathway concertedly. Here, we show that essential PCP signaling components, encoded by frizzled (fz), strabismus (stbm), flamingo (fmi), and dishevelled (dsh), are cooperatively required for axonal targeting and branching of the Drosophila mushroom body (MB) neurons. A detailed analysis of these mutants revealed that these components were required for the correct targeting and bifurcation of axons. In addition, we suggest that Wnt5 functions as a ligand in the PCP pathway in this process. Wnt5 mutants showed similar phenotypes to PCP mutants at the single-cell level and genetically interacted with PCP genes. Wnt5 was broadly expressed in the developing brain. We propose that Wnt5 and the PCP pathway concertedly regulate axonal development of the MB.
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23
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Schachter H, Boulianne G. Life is sweet! A novel role for N-glycans in Drosophila lifespan. Fly (Austin) 2011; 5:18-24. [PMID: 21057214 DOI: 10.4161/fly.5.1.13920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
N-glycans are post-translational modifications in which the sugar chain is covalently linked to protein by a GlcNAcβ1-N-asparagine linkage. Drosophila melanogaster and other invertebrates, but not vertebrates, synthesize large amounts of "paucimannose" N-glycans that contain only three or four mannose residues. The enzyme UDP-GlcNAc:α3-D-mannoside β1,2-N-acetylglucosaminyltransferase I (GnTI, encoded by the Mgat1 gene) controls the synthesis of paucimannose N-glycans. Either deletion or neuron-specific knockdown of Mgat1 in wild type flies results in pronounced defects in locomotion, structural defects in the adult central nervous system and a severely reduced lifespan. We have recently shown that neuronal expression of a wild-type Mgat1 transgene in Mgat1-null flies rescues the structural defects in the brain (fused β-lobes) and the shortened lifespan and, surprisingly, results in a dramatic 135% increase in mean lifespan relative to genetically identical controls that do not express the transgene. In this review, we discuss various approaches that can be used to determine the roles of paucimannose N-glycans in Drosophila longevity and in the adult CNS.
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Affiliation(s)
- Harry Schachter
- Program in Molecular Structure and Function, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
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24
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Ryks: new partners for Wnts in the developing and regenerating nervous system. Trends Neurosci 2009; 33:84-92. [PMID: 20004982 DOI: 10.1016/j.tins.2009.11.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 10/08/2009] [Accepted: 11/17/2009] [Indexed: 12/21/2022]
Abstract
Conserved Ryk transmembrane proteins, tyrosine kinase-related Wnt receptors, are important during neurogenesis, axon guidance and synaptogenesis. Here, we review the increasingly complex biology of the Wnt/Ryk pathway, emphasizing the mechanisms by which Ryks transduce or sometimes block the Wnt signal. Recent studies reveal that Wnts signal through Ryk via multiple mechanisms, including nuclear translocation of their intracellular domains and pathways employing Src Family Kinases and members of the canonical Wnt pathway. We also discuss reports indicating that Wnt/Ryk axon guidance roles are evolutionarily conserved and Wnt/Ryk interactions are required for motoneuron target selection and synaptogenesis at the neuromuscular junction. Recent findings that injury-induced Wnt/Ryk pathway activation inhibits axon regeneration underscore the importance of further understanding this novel pathway.
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25
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Sakurai M, Aoki T, Yoshikawa S, Santschi LA, Saito H, Endo K, Ishikawa K, Kimura KI, Ito K, Thomas JB, Hama C. Differentially expressed Drl and Drl-2 play opposing roles in Wnt5 signaling during Drosophila olfactory system development. J Neurosci 2009; 29:4972-80. [PMID: 19369566 PMCID: PMC2749065 DOI: 10.1523/jneurosci.2821-08.2009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 01/22/2009] [Accepted: 02/21/2009] [Indexed: 11/21/2022] Open
Abstract
In Drosophila, odor information received by olfactory receptor neurons (ORNs) is processed by glomeruli, which are organized in a stereotypic manner in the antennal lobe (AL). This glomerular organization is regulated by Wnt5 signaling. In the embryonic CNS, Wnt5 signaling is transduced by the Drl receptor, a member of the Ryk family. During development of the olfactory system, however, it is antagonized by Drl. Here, we identify Drl-2 as a receptor mediating Wnt5 signaling. Drl is found in the neurites of brain cells in the AL and specific glia, whereas Drl-2 is predominantly found in subsets of growing ORN axons. A drl-2 mutation produces only mild deficits in glomerular patterning, but when it is combined with a drl mutation, the phenotype is exacerbated and more closely resembles the Wnt5 phenotype. Wnt5 overexpression in ORNs induces aberrant glomeruli positioning. This phenotype is ameliorated in the drl-2 mutant background, indicating that Drl-2 mediates Wnt5 signaling. In contrast, forced expression of Drl-2 in the glia of drl mutants rescues the glomerular phenotype caused by the loss of antagonistic Drl function. Therefore, Drl-2 can also antagonize Wnt5 signaling. Additionally, our genetic data suggest that Drl localized to developing glomeruli mediates Wnt5 signaling. Thus, these two members of the Ryk family are capable of carrying out a similar molecular function, but they can play opposing roles in Wnt5 signaling, depending on the type of cells in which they are expressed. These molecules work cooperatively to establish the olfactory circuitry in Drosophila.
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Affiliation(s)
- Masao Sakurai
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
| | - Tomoko Aoki
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
| | - Shingo Yoshikawa
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037-1099
| | - Linda A. Santschi
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037-1099
- Coastal Marine Biolabs, Ventura, California 93001
| | - Hiroko Saito
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
| | - Keita Endo
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan, and
| | - Kyoko Ishikawa
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
| | - Ken-ichi Kimura
- Hokkaido University of Education, Iwamizawa Campus, Hokkaido 068-8642, Japan
| | - Kei Ito
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan, and
| | - John B. Thomas
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037-1099
| | - Chihiro Hama
- Laboratory for Neural Network Development, RIKEN Center for Developmental Biology, Hyogo 650-0047, Japan
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26
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Aso Y, Grübel K, Busch S, Friedrich AB, Siwanowicz I, Tanimoto H. The mushroom body of adult Drosophila characterized by GAL4 drivers. J Neurogenet 2009; 23:156-72. [PMID: 19140035 DOI: 10.1080/01677060802471718] [Citation(s) in RCA: 280] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The mushroom body is required for a variety of behaviors of Drosophila melanogaster. Different types of intrinsic and extrinsic mushroom body neurons might underlie its functional diversity. There have been many GAL4 driver lines identified that prominently label the mushroom body intrinsic neurons, which are known as "Kenyon cells." Under one constant experimental condition, we analyzed and compared the the expression patterns of 25 GAL4 drivers labeling the mushroom body. As an internet resource, we established a digital catalog indexing representative confocal data of them. Further more, we counted the number of GAL4-positive Kenyon cells in each line. We found that approximately 2,000 Kenyon cells can be genetically labeled in total. Three major Kenyon cell subtypes, the gamma, alpha'/beta', and alpha/beta neurons, respectively, contribute to 33, 18, and 49% of 2,000 Kenyon cells. Taken together, this study lays groundwork for functional dissection of the mushroom body.
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Affiliation(s)
- Yoshinori Aso
- Max-Planck-Institut für Neurobiologie, Martinsried, Germany
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27
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Wouda RR, Bansraj MRKS, de Jong AWM, Noordermeer JN, Fradkin LG. Src family kinases are required for WNT5 signaling through the Derailed/RYK receptor in the Drosophila embryonic central nervous system. Development 2008; 135:2277-87. [PMID: 18539923 DOI: 10.1242/dev.017319] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Members of the RYK/Derailed family have recently been shown to regulate axon guidance in both Drosophila and mammals by acting as Wnt receptors. Little is known about how the kinase activity-deficient RYKs transduce Wnt signals. Here, we show that the non-receptor Src family tyrosine kinases, SRC64B and SRC42A, are involved in WNT5-mediated signaling through Derailed in the Drosophila embryonic central nervous system. Analysis of animals lacking SRC64B and SRC42A reveals defects in commissure formation similar to those observed in Wnt5 and derailed mutants. Reductions in SRC64B expression levels suppress a Wnt5/derailed-dependent dominant gain-of-function phenotype, and increased levels of either SRC64B or SRC42A enhance Wnt5/derailed-mediated axon commissure switching. Derailed and SRC64B form a complex, which contains catalytically active SRC64B, the formation or stability of which requires SRC64B kinase activity. Furthermore, Derailed is phosphorylated in a SRC64B-dependent manner and coexpression of Derailed and SRC64B results in the activation of SRC64B. The mammalian orthologs of Derailed and SRC64B also form complexes, suggesting that Src roles in RYK signaling are conserved. Finally, we show that coexpression of WNT5 and Derailed has no apparent effect upon TCF/LEF-dependent transcription, suggesting that the WNT5/Derailed signaling pathway is unlikely to directly regulate canonical Wnt pathway targets. Together, these findings indicate that the Src family kinases play novel roles in WNT5/Derailed-mediated signaling.
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Affiliation(s)
- Rene R Wouda
- Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands
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