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Sun Y, Zhao Y, Johnson TK, Xie W. Immunohistochemical Analysis of the Drosophila Larval Neuromuscular Junction. Methods Mol Biol 2024; 2746:201-211. [PMID: 38070091 DOI: 10.1007/978-1-0716-3585-8_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Synapses are specialized junctions between cells that mediate neurotransmission to modify brain activity and body function. Studies on synapse structure and function play an important role in understanding how neurons communicate and the consequences of their dysfunction in neurological disorders. The Drosophila larval neuromuscular junction is an excellent model for dissecting the cellular and molecular mechanisms of the synapse, with its large size, accessibility, and well-characterized genetics. This protocol describes the steps required for morphological and immunohistochemical analysis of the Drosophila larval neuromuscular junction including its dissection and multiplex labeling of synaptic proteins. This technique can be used to assess the impact of genetic manipulations on synaptic development, integrity, and plasticity, thus providing a valuable tool for probing complex neurological processes in a whole animal system.
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Affiliation(s)
- Yichen Sun
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China.
- School of Biological Sciences, Monash University, Clayton, VIC, Australia.
| | - Yu Zhao
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China
| | - Travis K Johnson
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
- Department of Biochemistry and Chemistry, and La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, Australia
| | - Wei Xie
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, China
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2
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Xiao C, M’Angale PG, Wang S, Lemieux A, Thomson T. Identifying new players in structural synaptic plasticity through dArc1 interrogation. iScience 2023; 26:108048. [PMID: 37876812 PMCID: PMC10590816 DOI: 10.1016/j.isci.2023.108048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/28/2023] [Accepted: 09/22/2023] [Indexed: 10/26/2023] Open
Abstract
The formation, expansion, and pruning of synapses, known as structural synaptic plasticity, is needed for learning and memory, and perturbation of plasticity is associated with many neurological disorders and diseases. Previously, we observed that the Drosophila homolog of Activity-regulated cytoskeleton-associated protein (dArc1), forms a capsid-like structure, associates with its own mRNA, and is transported across synapses. We demonstrated that this transfer is needed for structural synaptic plasticity. To identify mRNAs that are modified by dArc1 in presynaptic neuron and postsynaptic muscle, we disrupted the expression of dArc1 and performed genomic analysis with deep sequencing. We found that dArc1 affects the expression of genes involved in metabolism, phagocytosis, and RNA-splicing. Through immunoprecipitation we also identified potential mRNA cargos of dArc1 capsids. This study suggests that dArc1 acts as a master regulator of plasticity by affecting several distinct and highly conserved cellular processes.
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Affiliation(s)
- Cong Xiao
- Department of Neurobiology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - P. Githure M’Angale
- Department of Neurobiology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Shuhao Wang
- Department of Neurobiology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Adrienne Lemieux
- Department of Neurobiology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Travis Thomson
- Department of Neurobiology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
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3
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Sahota VK, Stone A, Woodling NS, Spiers JG, Steinert JR, Partridge L, Augustin H. Plum modulates Myoglianin and regulates synaptic function in D. melanogaster. Open Biol 2023; 13:230171. [PMID: 37699519 PMCID: PMC10497343 DOI: 10.1098/rsob.230171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
Alterations in the neuromuscular system underlie several neuromuscular diseases and play critical roles in the development of sarcopenia, the age-related loss of muscle mass and function. Mammalian Myostatin (MST) and GDF11, members of the TGF-β superfamily of growth factors, are powerful regulators of muscle size in both model organisms and humans. Myoglianin (MYO), the Drosophila homologue of MST and GDF11, is a strong inhibitor of synaptic function and structure at the neuromuscular junction in flies. Here, we identified Plum, a transmembrane cell surface protein, as a modulator of MYO function in the larval neuromuscular system. Reduction of Plum in the larval body-wall muscles abolishes the previously demonstrated positive effect of attenuated MYO signalling on both muscle size and neuromuscular junction structure and function. In addition, downregulation of Plum on its own results in decreased synaptic strength and body weight, classifying Plum as a (novel) regulator of neuromuscular function and body (muscle) size. These findings offer new insights into possible regulatory mechanisms behind ageing- and disease-related neuromuscular dysfunctions in humans and identify potential targets for therapeutic interventions.
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Affiliation(s)
- Virender K. Sahota
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Aelfwin Stone
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Nathaniel S. Woodling
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Jereme G. Spiers
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Joern R. Steinert
- Faculty of Medicine & Health Sciences, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Linda Partridge
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
| | - Hrvoje Augustin
- Department of Biological Sciences, Centre for Biomedical Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- Institute of Healthy Ageing, and GEE, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, Cologne 50931, Germany
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4
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Chakravorty A, Sharma A, Sheeba V, Manjithaya R. Glutamatergic Synapse Dysfunction in Drosophila Neuromuscular Junctions Can Be Rescued by Proteostasis Modulation. Front Mol Neurosci 2022; 15:842772. [PMID: 35909443 PMCID: PMC9337869 DOI: 10.3389/fnmol.2022.842772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/25/2022] [Indexed: 11/29/2022] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the nervous system, and the Drosophila glutamatergic neuromuscular junctions (NMJs) offer a tractable platform to understand excitatory synapse biology both in health and disease. Synaptopathies are neurodegenerative diseases that are associated with synaptic dysfunction and often display compromised proteostasis. One such rare, progressive neurodegenerative condition, Spinocerebellar Ataxia Type 3 (SCA3) or Machado-Joseph Disease (MJD), is characterized by cerebellar ataxia, Parkinsonism, and degeneration of motor neuron synapses. While the polyQ repeat mutant protein ataxin-3 is implicated in MJD, it is unclear how it leads to impaired synaptic function. In this study, we indicated that a Drosophila model of MJD recapitulates characteristics of neurodegenerative disorders marked by motor neuron dysfunction. Expression of 78 polyQ repeats of mutant ataxin-3 protein in Drosophila motor neurons resulted in behavioral defects, such as impaired locomotion in both larval and adult stages. Furthermore, defects in eclosion and lifespan were observed in adult flies. Detailed characterization of larval glutamatergic neuromuscular junctions (NMJs) revealed defects in morphological features along with compromised NMJ functioning. Autophagy, one of the key proteostasis pathways, is known to be impaired in the case of several synaptopathies. Our study reveals that overexpression of the autophagy-related protein Atg8a rescued behavioral defects. Thus, we present a model for glutamatergic synapse dysfunction that recapitulates synaptic and behavioral deficits and show that it is an amenable system for carrying out genetic and chemical biology screens to identify potential therapeutic targets for synaptopathies.
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Affiliation(s)
- Anushka Chakravorty
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Ankit Sharma
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Vasu Sheeba
- Chronobiology and Behavioural Neurogenetics Laboratory, Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
- *Correspondence: Vasu Sheeba
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
- Ravi Manjithaya
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5
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Fenckova M, Muha V, Mariappa D, Catinozzi M, Czajewski I, Blok LER, Ferenbach AT, Storkebaum E, Schenck A, van Aalten DMF. Intellectual disability-associated disruption of O-GlcNAc cycling impairs habituation learning in Drosophila. PLoS Genet 2022; 18:e1010159. [PMID: 35500025 PMCID: PMC9140282 DOI: 10.1371/journal.pgen.1010159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 05/27/2022] [Accepted: 03/21/2022] [Indexed: 11/19/2022] Open
Abstract
O-GlcNAcylation is a reversible co-/post-translational modification involved in a multitude of cellular processes. The addition and removal of the O-GlcNAc modification is controlled by two conserved enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA). Mutations in OGT have recently been discovered to cause a novel Congenital Disorder of Glycosylation (OGT-CDG) that is characterized by intellectual disability. The mechanisms by which OGT-CDG mutations affect cognition remain unclear. We manipulated O-GlcNAc transferase and O-GlcNAc hydrolase activity in Drosophila and demonstrate an important role of O-GlcNAcylation in habituation learning and synaptic development at the larval neuromuscular junction. Introduction of patient-specific missense mutations into Drosophila O-GlcNAc transferase using CRISPR/Cas9 gene editing leads to deficits in locomotor function and habituation learning. The habituation deficit can be corrected by blocking O-GlcNAc hydrolysis, indicating that OGT-CDG mutations affect cognition-relevant habituation via reduced protein O-GlcNAcylation. This study establishes a critical role for O-GlcNAc cycling and disrupted O-GlcNAc transferase activity in cognitive dysfunction, and suggests that blocking O-GlcNAc hydrolysis is a potential strategy to treat OGT-CDG.
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Affiliation(s)
- Michaela Fenckova
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Villo Muha
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Daniel Mariappa
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marica Catinozzi
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Ignacy Czajewski
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Laura E. R. Blok
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Andrew T. Ferenbach
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Erik Storkebaum
- Department of Molecular Neurobiology, Donders Institute for Brain, Cognition and Behaviour, Faculty of Science, Radboud University, Nijmegen, Netherlands
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands
| | - Daan M. F. van Aalten
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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Ormerod KG, Scibelli AE, Littleton JT. Regulation of excitation-contraction coupling at the Drosophila neuromuscular junction. J Physiol 2022; 600:349-372. [PMID: 34788476 PMCID: PMC9044916 DOI: 10.1113/jp282092] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/28/2021] [Indexed: 01/05/2023] Open
Abstract
The Drosophila neuromuscular system is widely used to characterize synaptic development and function. However, little is known about how specific synaptic alterations effect neuromuscular transduction and muscle contractility, which ultimately dictate behavioural output. Here we develop and use a force transducer system to characterize excitation-contraction coupling at Drosophila larval neuromuscular junctions (NMJs), examining how specific neuronal and muscle manipulations disrupt muscle contractility. Muscle contraction force increased with motoneuron stimulation frequency and duration, showing considerable plasticity between 5 and 40 Hz and saturating above 50 Hz. Endogenous recordings of fictive contractions revealed average motoneuron burst frequencies of 20-30 Hz, consistent with the system operating within this plastic range of contractility. Temperature was also a key factor in muscle contractility, as force was enhanced at lower temperatures and dramatically reduced with increasing temperatures. Pharmacological and genetic manipulations of critical components of Ca2+ regulation in both pre- and postsynaptic compartments affected the strength and time course of muscle contractions. A screen for modulators of muscle contractility led to identification and characterization of the molecular and cellular pathway by which the FMRFa peptide, TPAEDFMRFa, increases muscle performance. These findings indicate Drosophila NMJs provide a robust system to correlate synaptic dysfunction, regulation and modulation to alterations in excitation-contraction coupling. KEY POINTS: Larval muscle contraction force increases with stimulation frequency and duration, revealing substantial plasticity between 5 and 40 Hz. Fictive contraction recordings demonstrate endogenous motoneuron burst frequencies consistent with the neuromuscular system operating within the range of greatest plasticity. Genetic and pharmacological manipulations of critical components of pre- and postsynaptic Ca2+ regulation significantly affect the strength and time course of muscle contractions. A screen for modulators of the excitation-contraction machinery identified a FMRFa peptide, TPAEDFMRFa and its associated signalling pathway, that dramatically increases muscle performance. Drosophila serves as an excellent model for dissecting components of the excitation-contraction coupling machinery.
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Affiliation(s)
- Kiel G Ormerod
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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7
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Goel P, Dickman D. Synaptic homeostats: latent plasticity revealed at the Drosophila neuromuscular junction. Cell Mol Life Sci 2021; 78:3159-3179. [PMID: 33449150 PMCID: PMC8044042 DOI: 10.1007/s00018-020-03732-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/19/2020] [Accepted: 12/04/2020] [Indexed: 12/11/2022]
Abstract
Homeostatic signaling systems are fundamental forms of biological regulation that maintain stable functionality in a changing environment. In the nervous system, synapses are crucial substrates for homeostatic modulation, serving to establish, maintain, and modify the balance of excitation and inhibition. Synapses must be sufficiently flexible to enable the plasticity required for learning and memory but also endowed with the stability to last a lifetime. In response to the processes of development, growth, remodeling, aging, and disease that challenge synapses, latent forms of adaptive plasticity become activated to maintain synaptic stability. In recent years, new insights into the homeostatic control of synaptic function have been achieved using the powerful Drosophila neuromuscular junction (NMJ). This review will focus on work over the past 10 years that has illuminated the cellular and molecular mechanisms of five homeostats that operate at the fly NMJ. These homeostats adapt to loss of postsynaptic neurotransmitter receptor functionality, glutamate imbalance, axonal injury, as well as aberrant synaptic growth and target innervation. These diverse homeostats work independently yet can be simultaneously expressed to balance neurotransmission. Growing evidence from this model glutamatergic synapse suggests these ancient homeostatic signaling systems emerged early in evolution and are fundamental forms of plasticity that also function to stabilize mammalian cholinergic NMJs and glutamatergic central synapses.
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Affiliation(s)
- Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Dion Dickman
- Department of Neurobiology, University of Southern California, Los Angeles, CA, 90089, USA.
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8
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Impairment of the mitochondrial one-carbon metabolism enzyme SHMT2 causes a novel brain and heart developmental syndrome. Acta Neuropathol 2020; 140:971-975. [PMID: 33015733 PMCID: PMC7665968 DOI: 10.1007/s00401-020-02223-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 02/06/2023]
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9
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Quinlan MA, Robson MJ, Ye R, Rose KL, Schey KL, Blakely RD. Ex vivo Quantitative Proteomic Analysis of Serotonin Transporter Interactome: Network Impact of the SERT Ala56 Coding Variant. Front Mol Neurosci 2020; 13:89. [PMID: 32581705 PMCID: PMC7295033 DOI: 10.3389/fnmol.2020.00089] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/28/2020] [Indexed: 12/15/2022] Open
Abstract
Altered serotonin (5-HT) signaling is associated with multiple brain disorders, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). The presynaptic, high-affinity 5-HT transporter (SERT) tightly regulates 5-HT clearance after release from serotonergic neurons in the brain and enteric nervous systems, among other sites. Accumulating evidence suggests that SERT is dynamically regulated in distinct activity states as a result of environmental and intracellular stimuli, with regulation perturbed by disease-associated coding variants. Our lab identified a rare, hypermorphic SERT coding substitution, Gly56Ala, in subjects with ASD, finding that the Ala56 variant stabilizes a high-affinity outward-facing conformation (SERT∗) that leads to elevated 5-HT uptake in vitro and in vivo. Hyperactive SERT Ala56 appears to preclude further activity enhancements by p38α mitogen-activated protein kinase (MAPK) and can be normalized by pharmacological p38α MAPK inhibition, consistent with SERT Ala56 mimicking, constitutively, a high-activity conformation entered into transiently by p38α MAPK activation. We hypothesize that changes in SERT-interacting proteins (SIPs) support the shift of SERT into the SERT∗ state which may be captured by comparing the composition of SERT Ala56 protein complexes with those of wildtype (WT) SERT, defining specific interactions through comparisons of protein complexes recovered using preparations from SERT–/– (knockout; KO) mice. Using quantitative proteomic-based approaches, we identify a total of 459 SIPs, that demonstrate both SERT specificity and sensitivity to the Gly56Ala substitution, with a striking bias being a loss of SIP interactions with SERT Ala56 compared to WT SERT. Among this group are previously validated SIPs, such as flotillin-1 (FLOT1) and protein phosphatase 2A (PP2A), whose functions are believed to contribute to SERT microdomain localization and regulation. Interestingly, our studies nominate a number of novel SIPs implicated in ASD, including fragile X mental retardation 1 protein (FMR1) and SH3 and multiple ankyrin repeat domains protein 3 (SHANK3), of potential relevance to long-standing evidence of serotonergic contributions to ASD. Further investigation of these SIPs, and the broader networks they engage, may afford a greater understanding of ASD as well as other brain and peripheral disorders associated with perturbed 5-HT signaling.
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Affiliation(s)
- Meagan A Quinlan
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, United States
| | - Matthew J Robson
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, United States
| | - Ran Ye
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Kristie L Rose
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Randy D Blakely
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Brain Institute, Florida Atlantic University, Jupiter, FL, United States
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Bai Y, Suzuki T. Activity-Dependent Synaptic Plasticity in Drosophila melanogaster. Front Physiol 2020; 11:161. [PMID: 32158405 PMCID: PMC7052306 DOI: 10.3389/fphys.2020.00161] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 02/12/2020] [Indexed: 01/17/2023] Open
Abstract
The Drosophila nervous system is a valuable model to examine the mechanisms of activity-dependent synaptic modification (plasticity) owing to its relatively simple organization and the availability of powerful genetic tools. The larval neuromuscular junction (NMJ) in particular is an accessible model for the study of synaptic development and plasticity. In addition to the NMJ, huge strides have also been made on understanding activity-dependent synaptic plasticity in the Drosophila olfactory and visual systems. In this review, we focus mainly on the underlying processes of activity-dependent synaptic plasticity at both pre-synaptic and post-synaptic terminals, and summarize current knowledge on activity-dependent synaptic plasticity in different parts of the Drosophila melanogaster nervous system (larval NMJ, olfactory system, larval visual system, and adult visual system). We also examine links between synaptic development and activity-dependent synaptic plasticity, and the relationships between morphological and physiological plasticity. We provide a point of view from which we discern that the underlying mechanism of activity-dependent plasticity may be common throughout the nervous systems in Drosophila melanogaster.
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Affiliation(s)
- Yiming Bai
- School of Life Sciences and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Takashi Suzuki
- School of Life Sciences and Technology, Tokyo Institute of Technology, Yokohama, Japan
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11
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Zhao G, Oztan A, Ye Y, Schwarz TL. Kinetochore Proteins Have a Post-Mitotic Function in Neurodevelopment. Dev Cell 2019; 48:873-882.e4. [PMID: 30827899 DOI: 10.1016/j.devcel.2019.02.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/14/2018] [Accepted: 01/31/2019] [Indexed: 01/04/2023]
Abstract
The kinetochore is a complex of proteins, broadly conserved from yeast to man, that resides at the centromere and is essential for chromosome segregation in dividing cells. There are no known functions of the core complex outside of the centromere. We now show that the proteins of the kinetochore have an essential post-mitotic function in neurodevelopment. At the embryonic neuromuscular junction of Drosophila melanogaster, mutation or knockdown of many kinetochore components cause neurites to overgrow and prevent formation of normal synaptic boutons. Kinetochore proteins were detected in synapses and axons in Drosophila. In post-mitotic cultured hippocampal neurons, knockdown of mis12 increased the filopodia-like protrusions in this region. We conclude that the proteins of the kinetochore are repurposed to sculpt developing synapses and dendrites and thereby contribute to the correct development of neuronal circuits in both invertebrates and mammals.
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Affiliation(s)
- Guoli Zhao
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Asli Oztan
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Yingzhi Ye
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas L Schwarz
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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12
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McDermott JE, Goldblatt D, Paradis S. Class 4 Semaphorins and Plexin-B receptors regulate GABAergic and glutamatergic synapse development in the mammalian hippocampus. Mol Cell Neurosci 2018; 92:50-66. [PMID: 29981480 PMCID: PMC6191356 DOI: 10.1016/j.mcn.2018.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 12/20/2022] Open
Abstract
To understand how proper circuit formation and function is established in the mammalian brain, it is necessary to define the genes and signaling pathways that instruct excitatory and inhibitory synapse development. We previously demonstrated that the ligand-receptor pair, Sema4D and Plexin-B1, regulates inhibitory synapse development on an unprecedentedly fast time-scale while having no effect on excitatory synapse development. Here, we report previously undescribed synaptogenic roles for Sema4A and Plexin-B2 and provide new insight into Sema4D and Plexin-B1 regulation of synapse development in rodent hippocampus. First, we show that Sema4a, Sema4d, Plxnb1, and Plxnb2 have distinct and overlapping expression patterns in neurons and glia in the developing hippocampus. Second, we describe a requirement for Plexin-B1 in both the presynaptic axon of inhibitory interneurons as well as the postsynaptic dendrites of excitatory neurons for Sema4D-dependent inhibitory synapse development. Third, we define a new synaptogenic activity for Sema4A in mediating inhibitory and excitatory synapse development. Specifically, we demonstrate that Sema4A signals through the same pathway as Sema4D, via the postsynaptic Plexin-B1 receptor, to promote inhibitory synapse development. However, Sema4A also signals through the Plexin-B2 receptor to promote excitatory synapse development. Our results shed new light on the molecular cues that promote the development of either inhibitory or excitatory synapses in the mammalian hippocampus.
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Affiliation(s)
| | - Dena Goldblatt
- Department of Biology, Brandeis University, Waltham, MA 02454, United States
| | - Suzanne Paradis
- Department of Biology, Brandeis University, Waltham, MA 02454, United States; Volen Center for Complex Systems, Brandeis University, Waltham, MA 02454, United States; National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, United States.
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13
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Dolón JF, Paniagua AE, Valle V, Segurado A, Arévalo R, Velasco A, Lillo C. Expression and localization of the polarity protein CRB2 in adult mouse brain: a comparison with the CRB1 rd8 mutant mouse model. Sci Rep 2018; 8:11652. [PMID: 30076417 PMCID: PMC6076319 DOI: 10.1038/s41598-018-30210-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 07/24/2018] [Indexed: 11/09/2022] Open
Abstract
Acquisition of cell polarization is essential for the performance of crucial functions, like a successful secretion and appropriate cell signaling in many tissues, and it depends on the correct functioning of polarity proteins, including the Crumbs complex. The CRB proteins, CRB1, CRB2 and CRB3, identified in mammals, are expressed in epithelial-derived tissues like brain, kidney and retina. CRB2 has a ubiquitous expression and has been detected in embryonic brain tissue; but currently there is no data regarding its localization in the adult brain. In our study, we characterized the presence of CRB2 in adult mice brain, where it is particularly enriched in cortex, hippocampus, hypothalamus and cerebellum. Double immunofluorescence analysis confirmed that CRB2 is a neuron-specific protein, present in both soma and projections where colocalizes with certain populations of exocytic and endocytic vesicles and with other members of the Crumbs complex. Finally, in the cortex of CRB1rd8 mutant mice that contain a mutation in the Crb1 gene generating a truncated CRB1 protein, there is an abnormal increase in the expression levels of the CRB2 protein which suggests a possible compensatory mechanism for the malfunction of CRB1 in this mutant background.
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Affiliation(s)
- Jorge F Dolón
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Antonio E Paniagua
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain.,Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, CA, 90095, USA
| | - Vicente Valle
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Alicia Segurado
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Rosario Arévalo
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Almudena Velasco
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain
| | - Concepción Lillo
- Institute of Neurosciences of Castilla y León, IBSAL, Cell Biology and Pathology, University of Salamanca, 37007, Salamanca, Spain.
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14
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Stocker B, Bochow C, Damrau C, Mathejczyk T, Wolfenberg H, Colomb J, Weber C, Ramesh N, Duch C, Biserova NM, Sigrist S, Pflüger HJ. Structural and Molecular Properties of Insect Type II Motor Axon Terminals. Front Syst Neurosci 2018; 12:5. [PMID: 29615874 PMCID: PMC5867341 DOI: 10.3389/fnsys.2018.00005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 02/26/2018] [Indexed: 11/25/2022] Open
Abstract
A comparison between the axon terminals of octopaminergic efferent dorsal or ventral unpaired median neurons in either desert locusts (Schistocerca gregaria) or fruit flies (Drosophila melanogaster) across skeletal muscles reveals many similarities. In both species the octopaminergic axon forms beaded fibers where the boutons or varicosities form type II terminals in contrast to the neuromuscular junction (NMJ) or type I terminals. These type II terminals are immunopositive for both tyramine and octopamine and, in contrast to the type I terminals, which possess clear synaptic vesicles, only contain dense core vesicles. These dense core vesicles contain octopamine as shown by immunogold methods. With respect to the cytomatrix and active zone peptides the type II terminals exhibit active zone-like accumulations of the scaffold protein Bruchpilot (BRP) only sparsely in contrast to the many accumulations of BRP identifying active zones of NMJ type I terminals. In the fruit fly larva marked dynamic changes of octopaminergic fibers have been reported after short starvation which not only affects the formation of new branches (“synaptopods”) but also affects the type I terminals or NMJs via octopamine-signaling (Koon et al., 2011). Our starvation experiments of Drosophila-larvae revealed a time-dependency of the formation of additional branches. Whereas after 2 h of starvation we find a decrease in “synaptopods”, the increase is significant after 6 h of starvation. In addition, we provide evidence that the release of octopamine from dendritic and/or axonal type II terminals uses a similar synaptic machinery to glutamate release from type I terminals of excitatory motor neurons. Indeed, blocking this canonical synaptic release machinery via RNAi induced downregulation of BRP in neurons with type II terminals leads to flight performance deficits similar to those observed for octopamine mutants or flies lacking this class of neurons (Brembs et al., 2007).
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Affiliation(s)
- Bettina Stocker
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Christina Bochow
- Institute of Biology, Genetics, Freie Universität Berlin, Berlin, Germany
| | - Christine Damrau
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Thomas Mathejczyk
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Heike Wolfenberg
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Julien Colomb
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Claudia Weber
- Institute of Biology, Genetics, Freie Universität Berlin, Berlin, Germany
| | - Niraja Ramesh
- Institute of Biology, Genetics, Freie Universität Berlin, Berlin, Germany
| | - Carsten Duch
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Natalia M Biserova
- Institute of Biology, Neurobiology, Freie Universität Berlin, Berlin, Germany
| | - Stephan Sigrist
- Institute of Biology, Genetics, Freie Universität Berlin, Berlin, Germany
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15
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Ashley J, Cordy B, Lucia D, Fradkin LG, Budnik V, Thomson T. Retrovirus-like Gag Protein Arc1 Binds RNA and Traffics across Synaptic Boutons. Cell 2018; 172:262-274.e11. [PMID: 29328915 PMCID: PMC5793882 DOI: 10.1016/j.cell.2017.12.022] [Citation(s) in RCA: 295] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 08/15/2017] [Accepted: 12/18/2017] [Indexed: 12/31/2022]
Abstract
Arc/Arg3.1 is required for synaptic plasticity and cognition, and mutations in this gene are linked to autism and schizophrenia. Arc bears a domain resembling retroviral/retrotransposon Gag-like proteins, which multimerize into a capsid that packages viral RNA. The significance of such a domain in a plasticity molecule is uncertain. Here, we report that the Drosophila Arc1 protein forms capsid-like structures that bind darc1 mRNA in neurons and is loaded into extracellular vesicles that are transferred from motorneurons to muscles. This loading and transfer depends on the darc1-mRNA 3' untranslated region, which contains retrotransposon-like sequences. Disrupting transfer blocks synaptic plasticity, suggesting that transfer of dArc1 complexed with its mRNA is required for this function. Notably, cultured cells also release extracellular vesicles containing the Gag region of the Copia retrotransposon complexed with its own mRNA. Taken together, our results point to a trans-synaptic mRNA transport mechanism involving retrovirus-like capsids and extracellular vesicles.
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Affiliation(s)
- James Ashley
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Benjamin Cordy
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Diandra Lucia
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Lee G Fradkin
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Vivian Budnik
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Travis Thomson
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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16
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PiT2 regulates neuronal outgrowth through interaction with microtubule-associated protein 1B. Sci Rep 2017; 7:17850. [PMID: 29259219 PMCID: PMC5736545 DOI: 10.1038/s41598-017-17953-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 12/04/2017] [Indexed: 01/30/2023] Open
Abstract
PiT2 is a member of the inorganic phosphate transporter family, and is extensively expressed in the nervous system. It was found that loop7 domain of PiT2 is not required for retroviral recognition and transport function. The exact functions of loop7 remain poorly understood. Here we show that loop7 of PiT2 is necessary for the transport of PiT2 protein to the cell surface. Further, loop7 is also related to the outgrowth of neurite in Neuro2A cells interacts with the light chain 1 of microtubule-associated protein 1B (MAP1B). PiT2 with mutated MAP1B binding sites affect neurite outgrowth whereas Pi transport function deficient mutants of PiT2 do not. We also show that Drosophila dPiT interacts with microtubule-associated protein Futsch, and dPiT is crucial for the normal development of neuromuscular junctions (NMJs). These results indicate that PiT2 might participate in the regulation of neuronal outgrowth by interacting with MAP1B and independently of its Pi transport function in the nervous system.
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17
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Luo J, Liu Y, Nässel DR. Transcriptional Reorganization of Drosophila Motor Neurons and Their Muscular Junctions toward a Neuroendocrine Phenotype by the bHLH Protein Dimmed. Front Mol Neurosci 2017; 10:260. [PMID: 28855860 PMCID: PMC5557793 DOI: 10.3389/fnmol.2017.00260] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 07/31/2017] [Indexed: 01/13/2023] Open
Abstract
Neuroendocrine cells store and secrete bulk amounts of neuropeptides, and display morphological and molecular characteristics distinct from neurons signaling with classical neurotransmitters. In Drosophila the transcription factor Dimmed (Dimm), is a prime organizer of neuroendocrine capacity in a majority of the peptidergic neurons. These neurons display large cell bodies and extensive axon terminations that commonly do not form regular synapses. We ask which molecular compartments of a neuron are affected by Dimm to generate these morphological features. Thus, we ectopically expressed Dimm in glutamatergic, Dimm-negative, motor neurons and analyzed their characteristics in the central nervous system and the neuromuscular junction. Ectopic Dimm results in motor neurons with enlarged cell bodies, diminished dendrites, larger axon terminations and boutons, as well as reduced expression of synaptic proteins both pre and post-synaptically. Furthermore, the neurons display diminished vesicular glutamate transporter, and signaling components known to sustain interactions between the developing axon termination and muscle, such as wingless and frizzled are down regulated. Ectopic co-expression of Dimm and the insulin receptor augments most of the above effects on the motor neurons. In summary, ectopic Dimm expression alters the glutamatergic motor neuron phenotype toward a neuroendocrine one, both pre- and post-synaptically. Thus, Dimm is a key organizer of both secretory capacity and morphological features characteristic of neuroendocrine cells, and this transcription factor affects also post-synaptic proteins.
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Affiliation(s)
- Jiangnan Luo
- Department of Zoology, Stockholm UniversityStockholm, Sweden
| | - Yiting Liu
- Department of Zoology, Stockholm UniversityStockholm, Sweden
| | - Dick R Nässel
- Department of Zoology, Stockholm UniversityStockholm, Sweden
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18
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Vonhoff F, Keshishian H. Activity-Dependent Synaptic Refinement: New Insights from Drosophila. Front Syst Neurosci 2017; 11:23. [PMID: 28484377 PMCID: PMC5399093 DOI: 10.3389/fnsys.2017.00023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/03/2017] [Indexed: 01/26/2023] Open
Abstract
During development, neurons establish inappropriate connections as they seek out their synaptic partners, resulting in supernumerary synapses that must be pruned away. The removal of miswired synapses usually involves electrical activity, often through a Hebbian spike-timing mechanism. A novel form of activity-dependent refinement is used by Drosophila that may be non-Hebbian, and is critical for generating the precise connectivity observed in that system. In Drosophila, motoneurons use both glutamate and the biogenic amine octopamine for neurotransmission, and the muscle fibers receive multiple synaptic inputs. Motoneuron growth cones respond in a time-regulated fashion to multiple chemotropic signals arising from their postsynaptic partners. Central to this mechanism is a very low frequency (<0.03 Hz) oscillation of presynaptic cytoplasmic calcium, that regulates and coordinates the action of multiple downstream effectors involved in the withdrawal from off-target contacts. Low frequency calcium oscillations are widely observed in developing neural circuits in mammals, and have been shown to be critical for normal connectivity in a variety of neural systems. In Drosophila these mechanisms allow the growth cone to sample widely among possible synaptic partners, evaluate opponent chemotropic signals, and withdraw from off-target contacts. It is possible that the underlying molecular mechanisms are conserved widely among invertebrates and vertebrates.
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Affiliation(s)
- Fernando Vonhoff
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| | - Haig Keshishian
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
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19
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Vonhoff F, Keshishian H. Cyclic nucleotide signaling is required during synaptic refinement at the Drosophila neuromuscular junction. Dev Neurobiol 2016; 77:39-60. [PMID: 27281494 DOI: 10.1002/dneu.22407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/07/2016] [Accepted: 06/07/2016] [Indexed: 01/01/2023]
Abstract
The removal of miswired synapses is a fundamental prerequisite for normal circuit development, leading to clinical problems when aberrant. However, the underlying activity-dependent molecular mechanisms involved in synaptic pruning remain incompletely resolved. Here the dynamic properties of intracellular calcium oscillations and a role for cAMP signaling during synaptic refinement in intact Drosophila embryos were examined using optogenetic tools. We provide In vivo evidence at the single gene level that the calcium-dependent adenylyl cyclase rutabaga, the phosphodiesterase dunce, the kinase PKA, and Protein Phosphatase 1 (PP1) all operate within a functional signaling pathway to modulate Sema2a-dependent chemorepulsion. It was found that presynaptic cAMP levels were required to be dynamically maintained at an optimal level to suppress connectivity defects. It was also proposed that PP1 may serve as a molecular link between cAMP signaling and CaMKII in the pathway underlying refinement. The results introduced an in vivo model where presynaptic cAMP levels, downstream of electrical activity and calcium influx, act via PKA and PP1 to modulate the neuron's response to chemorepulsion involved in the withdrawal of off-target synaptic contacts. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 39-60, 2017.
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Affiliation(s)
- Fernando Vonhoff
- Molecular, Cellular, and Developmental Biology Department, Yale University, POB 208103, New Haven, Connecticut, 06520
| | - Haig Keshishian
- Molecular, Cellular, and Developmental Biology Department, Yale University, POB 208103, New Haven, Connecticut, 06520
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20
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Ramirez J, Martinez A, Lectez B, Lee SY, Franco M, Barrio R, Dittmar G, Mayor U. Proteomic Analysis of the Ubiquitin Landscape in the Drosophila Embryonic Nervous System and the Adult Photoreceptor Cells. PLoS One 2015; 10:e0139083. [PMID: 26460970 PMCID: PMC4604154 DOI: 10.1371/journal.pone.0139083] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/09/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Ubiquitination is known to regulate physiological neuronal functions as well as to be involved in a number of neuronal diseases. Several ubiquitin proteomic approaches have been developed during the last decade but, as they have been mostly applied to non-neuronal cell culture, very little is yet known about neuronal ubiquitination pathways in vivo. METHODOLOGY/PRINCIPAL FINDINGS Using an in vivo biotinylation strategy we have isolated and identified the ubiquitinated proteome in neurons both for the developing embryonic brain and for the adult eye of Drosophila melanogaster. Bioinformatic comparison of both datasets indicates a significant difference on the ubiquitin substrates, which logically correlates with the processes that are most active at each of the developmental stages. Detection within the isolated material of two ubiquitin E3 ligases, Parkin and Ube3a, indicates their ubiquitinating activity on the studied tissues. Further identification of the proteins that do accumulate upon interference with the proteasomal degradative pathway provides an indication of the proteins that are targeted for clearance in neurons. Last, we report the proof-of-principle validation of two lysine residues required for nSyb ubiquitination. CONCLUSIONS/SIGNIFICANCE These data cast light on the differential and common ubiquitination pathways between the embryonic and adult neurons, and hence will contribute to the understanding of the mechanisms by which neuronal function is regulated. The in vivo biotinylation methodology described here complements other approaches for ubiquitome study and offers unique advantages, and is poised to provide further insight into disease mechanisms related to the ubiquitin proteasome system.
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Affiliation(s)
- Juanma Ramirez
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Aitor Martinez
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Benoit Lectez
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Mollecular Cell Biology, Turku Centre for Biotechnology, Turku, Finland
| | - So Young Lee
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Maribel Franco
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Developmental Neurobiology, Institute of Neurosciences, CSIC/UMH, Sant Joan d’Alacant, Alicante, Spain
| | - Rosa Barrio
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
| | - Gunnar Dittmar
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ugo Mayor
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
- Functional Genomics Unit, CIC bioGUNE, Derio, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia, Spain
- * E-mail:
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21
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Gardiol A, St Johnston D. Staufen targets coracle mRNA to Drosophila neuromuscular junctions and regulates GluRIIA synaptic accumulation and bouton number. Dev Biol 2014; 392:153-67. [PMID: 24951879 PMCID: PMC4111903 DOI: 10.1016/j.ydbio.2014.06.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/08/2014] [Accepted: 06/09/2014] [Indexed: 11/28/2022]
Abstract
The post-synaptic translation of localised mRNAs has been postulated to underlie several forms of plasticity at vertebrate synapses, but the mechanisms that target mRNAs to these postsynaptic sites are not well understood. Here we show that the evolutionary conserved dsRNA binding protein, Staufen, localises to the postsynaptic side of the Drosophila neuromuscular junction (NMJ), where it is required for the localisation of coracle mRNA and protein. Staufen plays a well-characterised role in the localisation of oskar mRNA to the oocyte posterior, where Staufen dsRNA-binding domain 5 is specifically required for its translation. Removal of Staufen dsRNA-binding domain 5, disrupts the postsynaptic accumulation of Coracle protein without affecting the localisation of cora mRNA, suggesting that Staufen similarly regulates Coracle translation. Tropomyosin II, which functions with Staufen in oskar mRNA localisation, is also required for coracle mRNA localisation, suggesting that similar mechanisms target mRNAs to the NMJ and the oocyte posterior. Coracle, the orthologue of vertebrate band 4.1, functions in the anchoring of the glutamate receptor IIA subunit (GluRIIA) at the synapse. Consistent with this, staufen mutant larvae show reduced accumulation of GluRIIA at synapses. The NMJs of staufen mutant larvae have also a reduced number of synaptic boutons. Altogether, this suggests that this novel Staufen-dependent mRNA localisation and local translation pathway may play a role in the developmentally regulated growth of the NMJ.
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Affiliation(s)
- Alejandra Gardiol
- The WellcomeCRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, United Kingdom
| | - Daniel St Johnston
- The WellcomeCRUK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, United Kingdom.
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22
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Loya CM, McNeill EM, Bao H, Zhang B, Van Vactor D. miR-8 controls synapse structure by repression of the actin regulator enabled. Development 2014; 141:1864-74. [PMID: 24718988 PMCID: PMC3994775 DOI: 10.1242/dev.105791] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play important roles in nervous system development and physiology. However, our understanding of the strategies by which miRNAs control synapse development is limited. We find that the highly conserved miRNA miR-8 regulates the morphology of presynaptic arbors at the Drosophila neuromuscular junction (NMJ) through a postsynaptic mechanism. Developmental analysis shows that miR-8 is required for presynaptic expansion that occurs in response to larval growth of the postsynaptic muscle targets. With an in vivo sensor, we confirm our hypothesis that the founding member of the conserved Ena/VASP (Enabled/Vasodilator Activated Protein) family is regulated by miR-8 through a conserved site in the Ena 3′ untranslated region (UTR). Synaptic marker analysis and localization studies suggest that Ena functions within the subsynaptic reticulum (SSR) surrounding presynaptic terminals. Transgenic lines that express forms of a conserved mammalian Ena ortholog further suggest that this localization and function of postsynaptic Ena/VASP family protein is dependent on conserved C-terminal domains known to mediate actin binding and assembly while antagonizing actin-capping proteins. Ultrastructural analysis demonstrates that miR-8 is required for SSR morphogenesis. As predicted by our model, we find that Ena is both sufficient and necessary to account for miR-8-mediated regulation of SSR architecture, consistent with its localization in this compartment. Finally, electrophysiological analysis shows that miR-8 is important for spontaneous neurotransmitter release frequency and quantal content. However, unlike the structural phenotypes, increased expression of Ena fails to mimic the functional defects observed in miR-8-null animals. Together, these findings suggest that miR-8 limits the expansion of presynaptic terminals during larval synapse development through regulation of postsynaptic actin assembly that is independent of changes in synapse physiology.
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Affiliation(s)
- Carlos M Loya
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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23
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Chia PH, Li P, Shen K. Cell biology in neuroscience: cellular and molecular mechanisms underlying presynapse formation. ACTA ACUST UNITED AC 2013; 203:11-22. [PMID: 24127213 PMCID: PMC3798257 DOI: 10.1083/jcb.201307020] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Synapse formation is a highly regulated process that requires the coordination of many cell biological events. Decades of research have identified a long list of molecular components involved in assembling a functioning synapse. Yet how the various steps, from transporting synaptic components to adhering synaptic partners and assembling the synaptic structure, are regulated and precisely executed during development and maintenance is still unclear. With the improvement of imaging and molecular tools, recent work in vertebrate and invertebrate systems has provided important insight into various aspects of presynaptic development, maintenance, and trans-synaptic signals, thereby increasing our understanding of how extrinsic organizers and intracellular mechanisms contribute to presynapse formation.
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Affiliation(s)
- Poh Hui Chia
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
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24
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Boulina M, Samarajeewa H, Baker JD, Kim MD, Chiba A. Live imaging of multicolor-labeled cells in Drosophila. Development 2013; 140:1605-13. [PMID: 23482495 DOI: 10.1242/dev.088930] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We describe LOLLIbow, a Brainbow-based live imaging system with applications in developmental biology and neurobiology. The development of an animal, including the environmentally sensitive adaptation of its brain, is thought to proceed through continual orchestration among diverse cell types as they divide, migrate, transform and interact with one another within the body. To facilitate direct visualization of such dynamic morphogenesis by individual cells in vivo, we have modified the original Brainbow for Drosophila in which live imaging is practical during much of its development. Our system offers permanent fluorescent labels that reveal fine morphological details of individual cells without requiring dissection or fixation of the samples. It also features a non-invasive means to control the timing of stochastic tricolor cell labeling with a light pulse. We demonstrate applicability of the new system in a variety of settings that could benefit from direct imaging of the developing multicellular organism with single-cell resolution.
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Affiliation(s)
- Maria Boulina
- Department of Biology, University of Miami, Coral Gables, FL 33146, USA
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25
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Menon KP, Carrillo RA, Zinn K. Development and plasticity of the Drosophila larval neuromuscular junction. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2013; 2:647-70. [PMID: 24014452 DOI: 10.1002/wdev.108] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Drosophila larval neuromuscular system is relatively simple, containing only 32 motor neurons in each abdominal hemisegment, and its neuromuscular junctions (NMJs) have been studied extensively. NMJ synapses exhibit developmental and functional plasticity while displaying stereotyped connectivity. Drosophila Type I NMJ synapses are glutamatergic, while the vertebrate NMJ uses acetylcholine as its primary neurotransmitter. The larval NMJ synapses use ionotropic glutamate receptors (GluRs) that are homologous to AMPA-type GluRs in the mammalian brain, and they have postsynaptic scaffolds that resemble those found in mammalian postsynaptic densities. These features make the Drosophila neuromuscular system an excellent genetic model for the study of excitatory synapses in the mammalian central nervous system. The first section of the review presents an overview of NMJ development. The second section describes genes that regulate NMJ development, including: (1) genes that positively and negatively regulate growth of the NMJ, (2) genes required for maintenance of NMJ bouton structure, (3) genes that modulate neuronal activity and alter NMJ growth, (4) genes involved in transsynaptic signaling at the NMJ. The third section describes genes that regulate acute plasticity, focusing on translational regulatory mechanisms. As this review is intended for a developmental biology audience, it does not cover NMJ electrophysiology in detail, and does not review genes for which mutations produce only electrophysiological but no structural phenotypes.
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Affiliation(s)
- Kaushiki P Menon
- Broad Center, Division of Biology, California Institute of Technology, Pasadena, CA, USA
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26
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Activity-dependent retrograde laminin A signaling regulates synapse growth at Drosophila neuromuscular junctions. Proc Natl Acad Sci U S A 2012; 109:17699-704. [PMID: 23054837 DOI: 10.1073/pnas.1206416109] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Retrograde signals induced by synaptic activities are derived from postsynaptic cells to potentiate presynaptic properties, such as cytoskeletal dynamics, gene expression, and synaptic growth. However, it is not known whether activity-dependent retrograde signals can also depotentiate synaptic properties. Here we report that laminin A (LanA) functions as a retrograde signal to suppress synapse growth at Drosophila neuromuscular junctions (NMJs). The presynaptic integrin pathway consists of the integrin subunit βν and focal adhesion kinase 56 (Fak56), both of which are required to suppress crawling activity-dependent NMJ growth. LanA protein is localized in the synaptic cleft and only muscle-derived LanA is functional in modulating NMJ growth. The LanA level at NMJs is inversely correlated with NMJ size and regulated by larval crawling activity, synapse excitability, postsynaptic response, and anterograde Wnt/Wingless signaling, all of which modulate NMJ growth through LanA and βν. Our data indicate that synaptic activities down-regulate levels of the retrograde signal LanA to promote NMJ growth.
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Brink DL, Gilbert M, Xie X, Petley-Ragan L, Auld VJ. Glial processes at the Drosophila larval neuromuscular junction match synaptic growth. PLoS One 2012; 7:e37876. [PMID: 22666403 PMCID: PMC3362601 DOI: 10.1371/journal.pone.0037876] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 04/25/2012] [Indexed: 11/19/2022] Open
Abstract
Glia are integral participants in synaptic physiology, remodeling and maturation from blowflies to humans, yet how glial structure is coordinated with synaptic growth is unknown. To investigate the dynamics of glial development at the Drosophila larval neuromuscular junction (NMJ), we developed a live imaging system to establish the relationship between glia, neuronal boutons, and the muscle subsynaptic reticulum. Using this system we observed processes from two classes of peripheral glia present at the NMJ. Processes from the subperineurial glia formed a blood-nerve barrier around the axon proximal to the first bouton. Processes from the perineurial glial extended beyond the end of the blood-nerve barrier into the NMJ where they contacted synapses and extended across non-synaptic muscle. Growth of the glial processes was coordinated with NMJ growth and synaptic activity. Increasing synaptic size through elevated temperature or the highwire mutation increased the extent of glial processes at the NMJ and conversely blocking synaptic activity and size decreased the presence and size of glial processes. We found that elevated temperature was required during embryogenesis in order to increase glial expansion at the nmj. Therefore, in our live imaging system, glial processes at the NMJ are likely indirectly regulated by synaptic changes to ensure the coordinated growth of all components of the tripartite larval NMJ.
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Affiliation(s)
- Deidre L. Brink
- Department of Zoology, Cell and Developmental Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mary Gilbert
- Department of Zoology, Cell and Developmental Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Xiaojun Xie
- Department of Zoology, Cell and Developmental Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lindsay Petley-Ragan
- Department of Zoology, Cell and Developmental Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vanessa J. Auld
- Department of Zoology, Cell and Developmental Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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28
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Hirsch HVB, Lnenicka G, Possidente D, Possidente B, Garfinkel MD, Wang L, Lu X, Ruden DM. Drosophila melanogaster as a model for lead neurotoxicology and toxicogenomics research. Front Genet 2012; 3:68. [PMID: 22586431 PMCID: PMC3343274 DOI: 10.3389/fgene.2012.00068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 04/09/2012] [Indexed: 01/01/2023] Open
Abstract
Drosophila melanogaster is an excellent model animal for studying the neurotoxicology of lead. It has been known since ancient Roman times that long-term exposure to low levels of lead results in behavioral abnormalities, such as what is now known as attention deficit hyperactivity disorder (ADHD). Because lead alters mechanisms that underlie developmental neuronal plasticity, chronic exposure of children, even at blood lead levels below the current CDC community action level (10 μg/dl), can result in reduced cognitive ability, increased likelihood of delinquency, behaviors associated with ADHD, changes in activity level, altered sensory function, delayed onset of sexual maturity in girls, and changes in immune function. In order to better understand how lead affects neuronal plasticity, we will describe recent findings from a Drosophila behavioral genetics laboratory, a Drosophila neurophysiology laboratory, and a Drosophila quantitative genetics laboratory who have joined forces to study the effects of lead on the Drosophila nervous system. Studying the effects of lead on Drosophila nervous system development will give us a better understanding of the mechanisms of Pb neurotoxicity in the developing human nervous system.
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Affiliation(s)
- Helmut V B Hirsch
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY, USA
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29
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Oh E, Robinson I. Barfly: sculpting membranes at the Drosophila neuromuscular junction. Dev Neurobiol 2012; 72:33-56. [PMID: 21630471 DOI: 10.1002/dneu.20923] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ability of a cell to change the shape of its membranes is intrinsic to many cellular functions. Proteins that can alter or recognize curved membrane structures and those that can act to recruit other proteins which stabilize the membrane curvature are likely to be essential in cell functions. The BAR (Bin, amphiphysin, RVS167 homology) domain is a protein domain that can either induce lipidic membranes to curve or can sense curved membranes. BAR domains are found in several proteins at neuronal synapses. We will review BAR domain structure and the role that BAR domain containing proteins play in regulating the morphology and function of the Drosophila neuromuscular junction. In flies the BAR domain containing proteins, endophilin and syndapin affect synaptic vesicle endocytosis, whereas CIP4, dRich, nervous wreck and syndapin affect synaptic morphology. We will review the growing evidence implicating mutations in BAR domain containing proteins being the cause of human pathologies.
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Affiliation(s)
- Eugene Oh
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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30
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Oliva C, Escobedo P, Astorga C, Molina C, Sierralta J. Role of the MAGUK protein family in synapse formation and function. Dev Neurobiol 2012; 72:57-72. [PMID: 21739617 DOI: 10.1002/dneu.20949] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Synaptic function is crucially dependent on the spatial organization of the presynaptic and postsynaptic apparatuses and the juxtaposition of both membrane compartments. This precise arrangement is achieved by a protein network at the submembrane region of each cell that is built around scaffold proteins. The membrane-associated guanylate kinase (MAGUK) family of proteins is a widely expressed and well-conserved group of proteins that plays an essential role in the formation and regulation of this scaffolding. Here, we review general features of this protein family, focusing on the discs large and calcium/calmodulin-dependent serine protein kinase subfamilies of MAGUKs in the formation, function, and plasticity of synapses.
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Affiliation(s)
- Carlos Oliva
- Program of Physiology and Biophysics, Institute of Biomedical Sciences and Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago 8380453, Chile
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31
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Broadie K, Baumgartner S, Prokop A. Extracellular matrix and its receptors in Drosophila neural development. Dev Neurobiol 2011; 71:1102-30. [PMID: 21688401 PMCID: PMC3192297 DOI: 10.1002/dneu.20935] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Extracellular matrix (ECM) and matrix receptors are intimately involved in most biological processes. The ECM plays fundamental developmental and physiological roles in health and disease, including processes underlying the development, maintenance, and regeneration of the nervous system. To understand the principles of ECM-mediated functions in the nervous system, genetic model organisms like Drosophila provide simple, malleable, and powerful experimental platforms. This article provides an overview of ECM proteins and receptors in Drosophila. It then focuses on their roles during three progressive phases of neural development: (1) neural progenitor proliferation, (2) axonal growth and pathfinding, and (3) synapse formation and function. Each section highlights known ECM and ECM-receptor components and recent studies done in mutant conditions to reveal their in vivo functions, all illustrating the enormous opportunities provided when merging work on the nervous system with systematic research into ECM-related gene functions.
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Affiliation(s)
- Kendal Broadie
- Departments of Biological Sciences and Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232 USA
| | - Stefan Baumgartner
- Department of Experimental Medical Sciences, Lund University, BMC B12, 22184 Lund, Sweden
| | - Andreas Prokop
- Faculty of Life Sciences, Wellcome Trust Centre for Cell-Matrix Research, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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32
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Knight D, Xie W, Boulianne GL. Neurexins and neuroligins: recent insights from invertebrates. Mol Neurobiol 2011; 44:426-40. [PMID: 22037798 PMCID: PMC3229692 DOI: 10.1007/s12035-011-8213-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 10/17/2011] [Indexed: 11/28/2022]
Abstract
During brain development, each neuron must find and synapse with the correct pre- and postsynaptic partners. The complexity of these connections and the relatively large distances some neurons must send their axons to find the correct partners makes studying brain development one of the most challenging, and yet fascinating disciplines in biology. Furthermore, once the initial connections have been made, the neurons constantly remodel their dendritic and axonal arbours in response to changing demands. Neurexin and neuroligin are two cell adhesion molecules identified as important regulators of this process. The importance of these genes in the development and modulation of synaptic connectivity is emphasised by the observation that mutations in these genes in humans have been associated with cognitive disorders such as Autism spectrum disorders, Tourette syndrome and Schizophrenia. The present review will discuss recent advances in our understanding of the role of these genes in synaptic development and modulation, and in particular, we will focus on recent work in invertebrate models, and how these results relate to studies in mammals.
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Affiliation(s)
- David Knight
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
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Sarthi J, Elefant F. dTip60 HAT activity controls synaptic bouton expansion at the Drosophila neuromuscular junction. PLoS One 2011; 6:e26202. [PMID: 22046262 PMCID: PMC3203119 DOI: 10.1371/journal.pone.0026202] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 09/22/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Histone acetylation of chromatin plays a key role in promoting the dynamic transcriptional responses in neurons that influence the neuroplasticity linked to cognitive ability, yet the specific histone acetyltransferases (HATs) that create such epigenetic marks remain to be elucidated. METHODS AND FINDINGS Here we use the Drosophila neuromuscular junction (NMJ) as a well-characterized synapse model to identify HATs that control synaptic remodeling and structure. We show that the HAT dTip60 is concentrated both pre and post-synaptically within the NMJ. Presynaptic targeted reduction of dTip60 HAT activity causes a significant increase in synaptic bouton number that specifically affects type Is boutons. The excess boutons show a suppression of the active zone synaptic function marker bruchpilot, suggesting defects in neurotransmission function. Analysis of microtubule organization within these excess boutons using immunohistochemical staining to the microtubule associated protein futsch reveals a significant increase in the rearrangement of microtubule loop architecture that is required for bouton division. Moreover, α-tubulin acetylation levels of microtubules specifically extending into the terminal synaptic boutons are reduced in response to dTip60 HAT reduction. CONCLUSIONS Our results are the first to demonstrate a causative role for the HAT dTip60 in the control of synaptic plasticity that is achieved, at least in part, via regulation of the synaptic microtubule cytoskeleton. These findings have implications for dTip60 HAT dependant epigenetic mechanisms underlying cognitive function.
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Affiliation(s)
- Jessica Sarthi
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - Felice Elefant
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, United States of America
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34
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Smith R, Taylor JP. Dissection and imaging of active zones in the Drosophila neuromuscular junction. J Vis Exp 2011:2676. [PMID: 21559003 DOI: 10.3791/2676] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The Drosophila larvae neuromuscular junction (NMJ) is an excellent model for the study of synaptic structure and function. Drosophila is well known for the ease of powerful genetic manipulations and the larval nervous system has proven particularly useful in studying not only normal function but also perturbations that accompany some neurological disease (Lloyd and Taylor, 2010). Many key synaptic molecules found in Drosophila are also found in mammals and like most CNS excitatory synapses in mammals, the Drosophila NMJ is glutamatergic and demonstrates activity-dependent remodeling (Koh et al. , 2000). Additionally, Drosophila neurons can be individually identified because their innervation patterns are stereotyped and repetitive making it possible to study identified synaptic terminals, such as those between motor neurons and the body-wall muscle fibers that they innervate (Keshishian and Kim, 2004). The existence of evolutionarily conserved synapse components along with the ease of genetic and physical manipulation make the Drosophila model ideal for investigating the mechanisms underlying synaptic function (Budnik, 1996). The active zones at synaptic terminals are of particular interest because these are the sites of neurotransmitter release. NC82 is a monoclonal antibody that recognizes the Drosophila protein Bruchpilot (Brp), a CAST1/ERC family member that is an important component of the active zone (Wagh et al. , 2006). Brp was shown to directly shape the active zone T-bar and is responsible for effectively clustering Ca(2+) channels beneath the T-bar density (Fouquet et al. , 2009). Mutants of Brp have reduced Ca(2+) channel density, depressed evoked vesicle release, and altered short-term plasticity (Kittel et al., 2006). Alterations to active zones have been observed in Drosophila disease models. For example, immunofluorescence using the NC82 antibody showed that the active zone density was decreased in models of amyotrophic lateral sclerosis and Pitt-Hopkins syndrome (Ratnaparkhi et al. , 2008; Zweier et al. , 2009). Thus, evaluation of active zones, or other synaptic proteins, in Drosophila larvae models of disease may provide a valuable initial clue to the presence of a synaptic defect. Preparing whole-mount dissected Drosophila larvae for immunofluorescence analysis of the NMJ requires some skill, but can be accomplished by most scientists with a little practice. Presented is a method that provides for multiple larvae to be dissected and immunostained in the same dissection dish, limiting environmental differences between each genotype and providing sufficient animals for confidence in reproducibility and statistical analysis.
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Affiliation(s)
- Rebecca Smith
- Developmental Neurobiology, St. Jude Children's Research Hospital, USA
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35
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Godena VK, Romano G, Romano M, Appocher C, Klima R, Buratti E, Baralle FE, Feiguin F. TDP-43 regulates Drosophila neuromuscular junctions growth by modulating Futsch/MAP1B levels and synaptic microtubules organization. PLoS One 2011; 6:e17808. [PMID: 21412434 PMCID: PMC3055892 DOI: 10.1371/journal.pone.0017808] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 02/11/2011] [Indexed: 12/13/2022] Open
Abstract
TDP-43 is an evolutionarily conserved RNA binding protein recently associated with the pathogenesis of different neurological diseases. At the moment, neither its physiological role in vivo nor the mechanisms that may lead to neurodegeneration are well known. Previously, we have shown that TDP-43 mutant flies presented locomotive alterations and structural defects at the neuromuscular junctions. We have now investigated the functional mechanism leading to these phenotypes by screening several factors known to be important for synaptic growth or bouton formation. As a result we found that alterations in the organization of synaptic microtubules correlate with reduced protein levels in the microtubule associated protein futsch/MAP1B. Moreover, we observed that TDP-43 physically interacts with futsch mRNA and that its RNA binding capacity is required to prevent futsch down regulation and synaptic defects.
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Affiliation(s)
- Vinay K. Godena
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Giulia Romano
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Maurizio Romano
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Chiara Appocher
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Raffaella Klima
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Emanuele Buratti
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Francisco E. Baralle
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
- * E-mail: (FEB); (FF)
| | - Fabian Feiguin
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
- * E-mail: (FEB); (FF)
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36
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Chen HJ, Anagnostou G, Chai A, Withers J, Morris A, Adhikaree J, Pennetta G, de Belleroche JS. Characterization of the properties of a novel mutation in VAPB in familial amyotrophic lateral sclerosis. J Biol Chem 2010; 285:40266-81. [PMID: 20940299 PMCID: PMC3001007 DOI: 10.1074/jbc.m110.161398] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Following the mutation screening of genes known to cause amyotrophic lateral sclerosis (ALS) in index cases from 107 familial ALS (FALS) kindred, a point mutation was identified in vesicle-associated membrane protein-associated protein B (VAPB), or VAMP-associated protein B, causing an amino acid change from threonine to isoleucine at codon 46 (T46I) in one FALS case but not in 257 controls. This is an important finding because it is only the second mutation identified in this gene that causes ALS. In order to investigate the pathogenic effects of this mutation, we have used a motor neuron cell line and tissue-specific expression of the mutant protein in Drosophila. We provide substantial evidence for the pathogenic effects of this mutation in abolishing the effect of wild type VAPB in the unfolded protein response, promoting ubiquitin aggregate formation, and activating neuronal cell death. We also report that expression of the mutant protein in the Drosophila motor system induces aggregate deposition, endoplasmic reticulum disorganization, and chaperone up-regulation both in neurons and in muscles. Our integrated analysis of the pathogenic effect of the T46I mutation and the previously identified P56S mutation indicate extensive commonalities in the disease mechanism for these two mutations. In summary, we show that this newly identified mutation in human FALS has a pathogenic effect, supporting and reinforcing the role of VAPB as a causative gene of ALS.
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Affiliation(s)
- Han-Jou Chen
- Division of Experimental Medicine, Faculty of Medicine, Centre for Neuroscience, Hammersmith Hospital, Imperial College London, London W12 0NN, United Kingdom
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37
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Xiong XD, Chen GH. Research progress on the age-related changes in proteins of the synaptic active zone. Physiol Behav 2010; 101:1-12. [PMID: 20433861 DOI: 10.1016/j.physbeh.2010.04.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 01/21/2023]
Abstract
Neurotransmitter release during synaptic transmission is mediated by the presynaptic active zone. Multiple protein components at the active zone region interact to regulate docking, priming and fusion of the synaptic vesicles with the presynaptic membrane to maintain normal neurotransmitter release. This review discusses research progress in questions of protein transcript and expression pattern changes at the synaptic active zone related to aging and whether these changes have the effects on learning and memory. We will specifically address normal synaptic structure and proteins; active zone structure and components; active zone functional regulation and age-related changes in active zone proteins.
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Affiliation(s)
- Xiang-Dong Xiong
- People's Hospital of Lu'an City (The Fifth Clinical College of Anhui Medical University), Lu'an City 237005, Anhui Province, PR China.
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38
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Groh C, Meinertzhagen IA. Brain plasticity in Diptera and Hymenoptera. Front Biosci (Schol Ed) 2010; 2:268-88. [PMID: 20036946 DOI: 10.2741/s63] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To mediate different types of behaviour, nervous systems need to coordinate the proper operation of their neural circuits as well as short- and long-term alterations that occur within those circuits. The latter ultimately devolve upon specific changes in neuronal structures, membrane properties and synaptic connections that are all examples of plasticity. This reorganization of the adult nervous system is shaped by internal and external influences both during development and adult maturation. In adults, behavioural experience is a major driving force of neuronal plasticity studied particularly in sensory systems. The range of adaptation depends on features that are important to a particular species, and is therefore specific, so that learning is essential for foraging in honeybees, while regenerative capacities are important in hemimetabolous insects with long appendages. Experience is usually effective during a critical period in early adult life, when neural function becomes tuned to future conditions in an insect's life. Tuning occur at all levels, in synaptic circuits, neuropile volumes, and behaviour. There are many examples, and this review incorporates only a select few, mainly those from Diptera and Hymenoptera.
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Affiliation(s)
- Claudia Groh
- Life Sciences Centre, Dalhousie University, Halifax, NS, Canada B3H 4J1
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39
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Rand MD. Drosophotoxicology: the growing potential for Drosophila in neurotoxicology. Neurotoxicol Teratol 2009; 32:74-83. [PMID: 19559084 DOI: 10.1016/j.ntt.2009.06.004] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 05/26/2009] [Accepted: 06/08/2009] [Indexed: 02/04/2023]
Abstract
Understanding neurotoxic mechanisms is a challenge of deciphering which genes and gene products in the developing or mature nervous system are targeted for disruption by chemicals we encounter in our environment. Our understanding of nervous system development and physiology is highly advanced due in large part to studies conducted in simple non-mammalian models. The paucity of toxicological data for the more than 80,000 chemicals in commercial use today, and the approximately 2000 new chemicals introduced each year, makes development of sensitive and rapid assays to screen for neurotoxicity paramount. In this article I advocate the use of Drosophila in the modern regimen of toxicological testing, emphasizing its unique attributes for assaying neurodevelopment and behavior. Features of the Drosophila model are reviewed and a generalized overall scheme for its use in toxicology is presented. Examples of where the fly has proven fruitful in evaluating common toxicants in our environment are also highlighted. Attention is drawn to three areas where development and application of the fly model might benefit toxicology the most: 1) optimizing sensitive endpoints for pathway-specific screening, 2) accommodating high throughput demands for analysis of chemical toxicant libraries, 3) optimizing genetic and molecular protocols for more rapid identification toxicant-by-gene interactions. While there are shortcomings in the Drosophila model, which exclude it from effective toxicological testing in certain arenas, conservation of fundamental cellular and developmental mechanisms between flies and man is extensive enough to warrant a central role for the Drosophila model in toxicological testing of today.
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Affiliation(s)
- Matthew D Rand
- Department of Anatomy and Neurobiology, College of Medicine, University of Vermont, Burlington, VT 05405, USA.
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40
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Peron S, Zordan MA, Magnabosco A, Reggiani C, Megighian A. From action potential to contraction: neural control and excitation-contraction coupling in larval muscles of Drosophila. Comp Biochem Physiol A Mol Integr Physiol 2009; 154:173-83. [PMID: 19427393 DOI: 10.1016/j.cbpa.2009.04.626] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 04/16/2009] [Accepted: 04/22/2009] [Indexed: 11/17/2022]
Abstract
The neuromuscular system of Drosophila melanogaster has been studied for many years for its relative simplicity and because of the genetic and molecular versatilities. Three main types of striated muscles are present in this dipteran: fibrillar muscles, tubular muscles and supercontractile muscles. The visceral muscles in adult flies and the body wall segmental muscles in embryos and larvae belong to the group of supercontractile muscles. Larval body wall muscles have been the object of detailed studies as a model for neuromuscular junction function but have received much less attention with respect to their mechanical properties and to the control of contraction. In this review we wish to assess available information on the physiology of the Drosophila larval muscular system. Our aim is to establish whether this system has the requisites to be considered a good model in which to perform a functional characterization of Drosophila genes, with a known muscular expression, as well as Drosophila homologs of human genes, the dysfunction of which, is known to be associated with human hereditary muscle pathologies.
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Affiliation(s)
- Samantha Peron
- Department of Anatomy and Physiology, University of Padua, Italy
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41
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Rushton E, Rohrbough J, Broadie K. Presynaptic secretion of mind-the-gap organizes the synaptic extracellular matrix-integrin interface and postsynaptic environments. Dev Dyn 2009; 238:554-71. [PMID: 19235718 PMCID: PMC2677818 DOI: 10.1002/dvdy.21864] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Mind-the-Gap (MTG) is required during synaptogenesis of the Drosophila glutamatergic neuromuscular junction (NMJ) to organize the postsynaptic domain. Here, we generate MTG::GFP transgenic animals to demonstrate MTG is synaptically targeted, secreted, and localized to punctate domains in the synaptic extracellular matrix (ECM). Drosophila NMJs form specialized ECM carbohydrate domains, with carbohydrate moieties and integrin ECM receptors occupying overlapping territories. Presynaptically secreted MTG recruits and reorganizes secreted carbohydrates, and acts to recruit synaptic integrins and ECM glycans. Transgenic MTG::GFP expression rescues hatching, movement, and synaptogenic defects in embryonic-lethal mtg null mutants. Targeted neuronal MTG expression rescues mutant synaptogenesis defects, and increases rescue of adult viability, supporting an essential neuronal function. These results indicate that presynaptically secreted MTG regulates the ECM-integrin interface, and drives an inductive mechanism for the functional differentiation of the postsynaptic domain of glutamatergic synapses. We suggest that MTG pioneers a novel protein family involved in ECM-dependent synaptic differentiation.
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Affiliation(s)
| | | | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt Brain Institute, Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee
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42
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Schwenkert I, Eltrop R, Funk N, Steinert JR, Schuster CM, Scholz H. The hangover gene negatively regulates bouton addition at the Drosophila neuromuscular junction. Mech Dev 2008; 125:700-11. [DOI: 10.1016/j.mod.2008.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 04/17/2008] [Accepted: 04/19/2008] [Indexed: 10/22/2022]
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43
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Le Mée G, Ezzeddine N, Capri M, Aït-Ahmed O. Repeat length and RNA expression level are not primary determinants in CUG expansion toxicity in Drosophila models. PLoS One 2008; 3:e1466. [PMID: 18213375 PMCID: PMC2186381 DOI: 10.1371/journal.pone.0001466] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 12/19/2007] [Indexed: 11/19/2022] Open
Abstract
Evidence for an RNA gain-of-function toxicity has now been provided for an increasing number of human pathologies. Myotonic dystrophies (DM) belong to a class of RNA-dominant diseases that result from RNA repeat expansion toxicity. Specifically, DM of type 1 (DM1), is caused by an expansion of CUG repeats in the 3'UTR of the DMPK protein kinase mRNA, while DM of type 2 (DM2) is linked to an expansion of CCUG repeats in an intron of the ZNF9 transcript (ZNF9 encodes a zinc finger protein). In both pathologies the mutant RNA forms nuclear foci. The mechanisms that underlie the RNA pathogenicity seem to be rather complex and not yet completely understood. Here, we describe Drosophila models that might help unravelling the molecular mechanisms of DM1-associated CUG expansion toxicity. We generated transgenic flies that express inducible repeats of different type (CUG or CAG) and length (16, 240, 480 repeats) and then analyzed transgene localization, RNA expression and toxicity as assessed by induced lethality and eye neurodegeneration. The only line that expressed a toxic RNA has a (CTG)(240) insertion. Moreover our analysis shows that its level of expression cannot account for its toxicity. In this line, (CTG)(240.4), the expansion inserted in the first intron of CG9650, a zinc finger protein encoding gene. Interestingly, CG9650 and (CUG)(240.4) expansion RNAs were found in the same nuclear foci. In conclusion, we suggest that the insertion context is the primary determinant for expansion toxicity in Drosophila models. This finding should contribute to the still open debate on the role of the expansions per se in Drosophila and in human pathogenesis of RNA-dominant diseases.
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Affiliation(s)
- Gwenn Le Mée
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, Montpellier, France
| | - Nader Ezzeddine
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, Montpellier, France
| | - Michèle Capri
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, Montpellier, France
| | - Ounissa Aït-Ahmed
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, Montpellier, France
- * To whom correspondence should be addressed. E-mail:
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44
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Reissner KJ, Boyle HD, Ye X, Carew TJ. Aplysia synapse associated protein (APSAP): identification, characterization, and selective interactions with Shaker-type potassium channels. J Neurochem 2007; 105:1006-18. [PMID: 18182049 DOI: 10.1111/j.1471-4159.2007.05202.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The vertebrate post-synaptic density (PSD) is a region of high molecular complexity in which dynamic protein interactions modulate receptor localization and synaptic function. Members of the membrane-associated guanylate kinase (MAGUK) family of proteins represent a major structural and functional component of the vertebrate PSD. In order to investigate the expression and significance of orthologous PSD components associated with the Aplysia sensory neuron-motor neuron synapse, we have cloned an Aplysia Dlg-MAGUK protein, which we identify as Aplysia synapse associated protein (ApSAP). As revealed by western blot, RT-PCR, and immunocytochemical analyses, ApSAP is predominantly expressed in the CNS and is located in both sensory neuron and motor neurons. The overall amino acid sequence of ApSAP is 55-61% identical to Drosophila Dlg and mammalian Dlg-MAGUK proteins, but is more highly conserved within L27, PDZ, SH3, and guanylate kinase domains. Because these conserved domains mediate salient interactions with receptors and other PSD components of the vertebrate synapse, we performed a series of GST pull-down assays using recombinant C-terminal tail proteins from various Aplysia receptors and channels containing C-terminal PDZ binding sequences. We have found that ApSAP selectively binds to an Aplysia Shaker-type channel AKv1.1, but not to (i) NMDA receptor subunit AcNR1-1, (ii) potassium channel AKv5.1, (iii) receptor tyrosine kinase ApTrkl, (iv) glutamate receptor ApGluR1/4, (v) glutamate receptor ApGluR2/3, or (vi) glutamate receptor ApGluR7. These findings provide preliminary information regarding the expression and interactions of Dlg-MAGUK proteins of the Aplysia CNS, and will inform questions aimed at a functional analysis of how interactions in a protein network such as the PSD may regulate synaptic strength.
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Affiliation(s)
- Kathryn J Reissner
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA
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Takizawa E, Komatsu A, Tsujimura H. Identification of common excitatory motoneurons in Drosophila melanogaster larvae. Zoolog Sci 2007; 24:504-13. [PMID: 17867850 DOI: 10.2108/zsj.24.504] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 11/28/2006] [Indexed: 11/17/2022]
Abstract
In insects, four types of motoneurons have long been known, including fast motoneurons, slow motoneurons, common inhibitory motoneurons, and DUM neurons. They innervate the same muscle and control its contraction together. Recent studies in Drosophila have suggested the existence of another type of motoneuron, the common excitatory motoneuron. Here, we found that shakB-GAL4 produced by labels this type of motoneuron in Drosophila larvae. We found that Drosophila larvae have two common excitatory motoneurons in each abdominal segment, RP2 for dorsal muscles and MNSNb/d-Is for ventral muscles. They innervate most of the internal longitudinal or oblique muscles on the dorsal or ventral body wall with type-Is terminals and use glutamate as a transmitter. Electrophysiological recording indicated that stimulation of the RP2 axon evoked excitatory junctional potential in a dorsal muscle.
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Affiliation(s)
- Eiji Takizawa
- Developmental Biology, Tokyo University of Agriculture and Technology, Fuchu-Shi, Tokyo, Japan
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46
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Kantardzhieva A, Alexeeva S, Versteeg I, Wijnholds J. MPP3 is recruited to the MPP5 protein scaffold at the retinal outer limiting membrane. FEBS J 2006; 273:1152-65. [PMID: 16519681 DOI: 10.1111/j.1742-4658.2006.05140.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mutations in the human Crumbs homologue 1 (CRB1) gene are a frequent cause of various forms of retinitis pigmentosa. The CRB1-membrane-associated palmitoylated protein (MPP)5 protein complex is thought to organize an intracellular protein scaffold in the retina that is involved in maintenance of photoreceptor-Müller glia cell adhesion. This study focused on the binding characteristics and subcellular localization of MPP3, a novel member of the MPP5 protein scaffold at the outer limiting membrane (OLM), and of the DLG1 protein scaffold at the outer plexiform layer of the retina. MPP3 localized at the photoreceptor synapse and at the subapical region adjacent to adherens junctions at the OLM. Localization studies in human retinae revealed that MPP3 colocalized with MPP5 and CRB1 at the subapical region. MPP3 and MPP4 colocalized with DLG1 at the outer plexiform layer. Mouse Dlg1 formed separate complexes with Mpp3 and Mpp4 in vivo. These data implicate a role for MPP3 in photoreceptor polarity and, by association with MPP5, pinpoint MPP3 as a functional candidate gene for inherited retinopathies. The separate Mpp3/Dlg1 and Mpp4/Dlg1 complexes at the outer plexiform layer point towards additional yet unrecognized functions of these membrane associated guanylate kinase proteins.
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Affiliation(s)
- Albena Kantardzhieva
- Department of Neuromedical Genetics, The Netherlands Institute for Neurosciences (NIN), KNAW, Amsterdam, The Netherlands
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Featherstone DE, Rushton E, Rohrbough J, Liebl F, Karr J, Sheng Q, Rodesch CK, Broadie K. An essential Drosophila glutamate receptor subunit that functions in both central neuropil and neuromuscular junction. J Neurosci 2006; 25:3199-208. [PMID: 15788777 PMCID: PMC2194804 DOI: 10.1523/jneurosci.4201-04.2005] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A Drosophila forward genetic screen for mutants with defective synaptic development identified bad reception (brec). Homozygous brec mutants are embryonic lethal, paralyzed, and show no detectable synaptic transmission at the glutamatergic neuromuscular junction (NMJ). Genetic mapping, complementation tests, and genomic sequencing show that brec mutations disrupt a previously uncharacterized ionotropic glutamate receptor subunit, named here "GluRIID." GluRIID is expressed in the postsynaptic domain of the NMJ, as well as widely throughout the synaptic neuropil of the CNS. In the NMJ of null brec mutants, all known glutamate receptor subunits are undetectable by immunocytochemistry, and all functional glutamate receptors are eliminated. Thus, we conclude that GluRIID is essential for the assembly and/or stabilization of glutamate receptors in the NMJ. In null brec mutant embryos, the frequency of periodic excitatory currents in motor neurons is significantly reduced, demonstrating that CNS motor pattern activity is regulated by GluRIID. Although synaptic development and molecular differentiation appear otherwise unperturbed in null mutants, viable hypomorphic brec mutants display dramatically undergrown NMJs by the end of larval development, suggesting that GluRIID-dependent central pattern activity regulates peripheral synaptic growth. These studies reveal GluRIID as a newly identified glutamate receptor subunit that is essential for glutamate receptor assembly/stabilization in the peripheral NMJ and required for properly patterned motor output in the CNS.
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Affiliation(s)
- David E Featherstone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
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Lee-Hoeflich ST, Zhao X, Mehra A, Attisano L. TheDrosophilatype II receptor, Wishful thinking, binds BMP and myoglianin to activate multiple TGFβ family signaling pathways. FEBS Lett 2005; 579:4615-21. [PMID: 16098524 DOI: 10.1016/j.febslet.2005.06.088] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 06/22/2005] [Accepted: 06/27/2005] [Indexed: 10/25/2022]
Abstract
Wishful thinking (Wit) is a Drosophila transforming growth factor-beta (TGFbeta) superfamily type II receptor most related to the mammalian bone morphogenetic protein (BMP) type II receptor, BMPRII. To better understand its function, we undertook a biochemical approach to establish the ligand binding repertoire and downstream signaling pathway. We observed that BMP4 and BMP7, bound to receptor complexes comprised of Wit and the type I receptor thickveins and saxophone to activate a BMP-like signaling pathway. Further we demonstrated that both myoglianin and its most closely related mammalian ligand, myostatin, interacted with a Wit and Baboon (Babo) type II-type I receptor complex to activate TGFbeta/activin-like signaling pathways. These results thereby demonstrate that Wit binds multiple ligands to activate both BMP and TGFbeta-like signaling pathways. Given that myoglianin is expressed in muscle and glial-derived cells, these results also suggest that Wit may mediate myoglianin-dependent signals in the nervous system.
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Morimoto-Tanifuji T, Kazama H, Nose A. Developmental stage-dependent modulation of synapses by postsynaptic expression of activated calcium/calmodulin-dependent protein kinase II. Neuroscience 2005; 128:797-806. [PMID: 15464287 DOI: 10.1016/j.neuroscience.2004.07.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2004] [Indexed: 11/25/2022]
Abstract
In Drosophila neuromuscular junctions, there is a unique system which consists of two neighboring muscles (M6 and M7) innervated by the same neurons and a gene of interest can be expressed in only M6 or in both muscles by GAL4-upstream activating sequence expression system. By using this system, we previously demonstrated that expression of activated calcium/calmodulin-dependent protein kinase II (CaMKII) in the muscle cell promotes coordinated maturation of pre- and postsynaptic sites of larvae just after hatching (JAH larvae) in a synapse-specific manner. Here we show that the promotive effects are no longer seen in the older larvae, 8-10 h after hatching (8 h AH larvae). Morphological studies indicate that CaMKII activation in fact reduces postsynaptic sites at 8 h AH. This is opposite to the effect observed in JAH larvae. These results suggest that the mode of CaMKII function switches during development, and that regulation of postsynaptic CaMKII activity is necessary for normal synaptic development. Finally, we report that in 8 h AH but not in JAH larvae, synapses on M7, in which CaMKII activity is not manipulated, are affected by the expression of activated CaMKII in M6. This suggests the interesting possibility that at certain developmental stages only, modification of synapses on one target cell can influence the synapses on another target cell innervated by the same neurons.
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Affiliation(s)
- T Morimoto-Tanifuji
- Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyoku, Tokyo 113-0033, Japan
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de Jong S, Cavallo JA, Rios CD, Dworak HA, Sink H. Target recognition and synaptogenesis by motor axons: responses to the sidestep protein. Int J Dev Neurosci 2004; 23:397-410. [PMID: 15927764 DOI: 10.1016/j.ijdevneu.2004.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 10/08/2004] [Accepted: 10/11/2004] [Indexed: 10/26/2022] Open
Abstract
Sidestep (Side) is a pivotal molecular player in embryonic motor axon pathfinding. But questions about its functional repertoire remain: (i) can Side permanently overturn targeting preferences? (ii) does it promote synaptogenesis, and (iii) can Side facilitate synaptic stabilization? To address these questions, Side was temporally and spatially misexpressed and the visible consequences for neuromuscular junction morphology were assessed. When Side was misexpressed either broadly or selectively in muscles during targeting in a wildtype background motor axon targeting preferences were permanently overturned. However the misexpression of Side in all muscles post-targeting neither changed synapse morphology, nor compensated for a lack of the synapse-stabilizing protein Fasciclin II (FasII). Rather Side appears to be dependent on FasII, instead of on intrinsic ability, for sustaining targeting changes. We propose that Side helps to bring motor axons to their correct muscle targets and promotes synaptogenesis, then FasII serves to stabilize the synaptic contacts.
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Affiliation(s)
- Samanta de Jong
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
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