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Zhang J, Tang T, Zhang R, Wen L, Deng X, Xu X, Yang W, Jin F, Cao Y, Lu Y, Yu XQ. Maintaining Toll signaling in Drosophila brain is required to sustain autophagy for dopamine neuron survival. iScience 2024; 27:108795. [PMID: 38292423 PMCID: PMC10825691 DOI: 10.1016/j.isci.2024.108795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 10/19/2023] [Accepted: 01/02/2024] [Indexed: 02/01/2024] Open
Abstract
Macroautophagy/autophagy is a conserved process in eukaryotic cells to degrade and recycle damaged intracellular components. Higher level of autophagy in the brain has been observed, and autophagy dysfunction has an impact on neuronal health, but the molecular mechanism is unclear. In this study, we showed that overexpression of Toll-1 and Toll-7 receptors, as well as active Spätzle proteins in Drosophila S2 cells enhanced autophagy, and Toll-1/Toll-7 activated autophagy was dependent on Tube-Pelle-PP2A. Interestingly, Toll-1 but not Toll-7 mediated autophagy was dMyd88 dependent. Importantly, we observed that loss of functions in Toll-1 and Toll-7 receptors and PP2A activity in flies decreased autophagy level, resulting in the loss of dopamine (DA) neurons and reduced fly motion. Our results indicated that proper activation of Toll-1 and Toll-7 pathways and PP2A activity in the brain are necessary to sustain autophagy level for DA neuron survival.
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Affiliation(s)
- Jie Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Ting Tang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Ruonan Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Liang Wen
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaojuan Deng
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoxia Xu
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Wanying Yang
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Fengliang Jin
- Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China
| | - Yang Cao
- Guangdong Laboratory for Lingnan Modern Agriculture, Laboratory of Insect Molecular Biology and Biotechnology, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Yuzhen Lu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiao-Qiang Yu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
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2
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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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3
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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4
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Atkinson NS. The Role of Toll and Nonnuclear NF-κB Signaling in the Response to Alcohol. Cells 2023; 12:1508. [PMID: 37296629 PMCID: PMC10252657 DOI: 10.3390/cells12111508] [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: 03/23/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
An understanding of neuroimmune signaling has become central to a description of how alcohol causes addiction and how it damages people with an AUD. It is well known that the neuroimmune system influences neural activity via changes in gene expression. This review discusses the roles played by CNS Toll-like receptor (TLR) signaling in the response to alcohol. Also discussed are observations in Drosophila that show how TLR signaling pathways can be co-opted by the nervous system and potentially shape behavior to a far greater extent and in ways different than generally recognized. For example, in Drosophila, TLRs substitute for neurotrophin receptors and an NF-κB at the end of a TLR pathway influences alcohol responsivity by acting non-genomically.
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Affiliation(s)
- Nigel S Atkinson
- Department of Neuroscience and The Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
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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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6
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Li G, Hidalgo A. The Toll Route to Structural Brain Plasticity. Front Physiol 2021; 12:679766. [PMID: 34290618 PMCID: PMC8287419 DOI: 10.3389/fphys.2021.679766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
The human brain can change throughout life as we learn, adapt and age. A balance between structural brain plasticity and homeostasis characterizes the healthy brain, and the breakdown of this balance accompanies brain tumors, psychiatric disorders, and neurodegenerative diseases. However, the link between circuit modifications, brain function, and behavior remains unclear. Importantly, the underlying molecular mechanisms are starting to be uncovered. The fruit-fly Drosophila is a very powerful model organism to discover molecular mechanisms and test them in vivo. There is abundant evidence that the Drosophila brain is plastic, and here we travel from the pioneering discoveries to recent findings and progress on molecular mechanisms. We pause on the recent discovery that, in the Drosophila central nervous system, Toll receptors—which bind neurotrophin ligands—regulate structural plasticity during development and in the adult brain. Through their topographic distribution across distinct brain modules and their ability to switch between alternative signaling outcomes, Tolls can enable the brain to translate experience into structural change. Intriguing similarities between Toll and mammalian Toll-like receptor function could reveal a further involvement in structural plasticity, degeneration, and disease in the human brain.
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Affiliation(s)
- Guiyi Li
- Plasticity and Regeneration Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Alicia Hidalgo
- Plasticity and Regeneration Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
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7
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Changes in Presynaptic Gene Expression during Homeostatic Compensation at a Central Synapse. J Neurosci 2021; 41:3054-3067. [PMID: 33608385 PMCID: PMC8026347 DOI: 10.1523/jneurosci.2979-20.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/02/2022] Open
Abstract
Homeostatic matching of pre- and postsynaptic function has been observed in many species and neural structures, but whether transcriptional changes contribute to this form of trans-synaptic coordination remains unknown. To identify genes whose expression is altered in presynaptic neurons as a result of perturbing postsynaptic excitability, we applied a transcriptomics-friendly, temperature-inducible Kir2.1-based activity clamp at the first synaptic relay of the Drosophila olfactory system, a central synapse known to exhibit trans-synaptic homeostatic matching. Twelve hours after adult-onset suppression of activity in postsynaptic antennal lobe projection neurons of males and females, we detected changes in the expression of many genes in the third antennal segment, which houses the somata of presynaptic olfactory receptor neurons. These changes affected genes with roles in synaptic vesicle release and synaptic remodeling, including several implicated in homeostatic plasticity at the neuromuscular junction. At 48 h and beyond, the transcriptional landscape tilted toward protein synthesis, folding, and degradation; energy metabolism; and cellular stress defenses, indicating that the system had been pushed to its homeostatic limits. Our analysis suggests that similar homeostatic machinery operates at peripheral and central synapses and identifies many of its components. The presynaptic transcriptional response to genetically targeted postsynaptic perturbations could be exploited for the construction of novel connectivity tracing tools. SIGNIFICANCE STATEMENT Homeostatic feedback mechanisms adjust intrinsic and synaptic properties of neurons to keep their average activity levels constant. We show that, at a central synapse in the fruit fly brain, these mechanisms include changes in presynaptic gene expression that are instructed by an abrupt loss of postsynaptic excitability. The trans-synaptically regulated genes have roles in synaptic vesicle release and synapse remodeling; protein synthesis, folding, and degradation; and energy metabolism. Our study establishes a role for transcriptional changes in homeostatic synaptic plasticity, points to mechanistic commonalities between peripheral and central synapses, and potentially opens new opportunities for the development of connectivity-based gene expression systems.
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8
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Mangold CA, Hughes DP. Insect Behavioral Change and the Potential Contributions of Neuroinflammation-A Call for Future Research. Genes (Basel) 2021; 12:465. [PMID: 33805190 PMCID: PMC8064348 DOI: 10.3390/genes12040465] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 12/21/2022] Open
Abstract
Many organisms are able to elicit behavioral change in other organisms. Examples include different microbes (e.g., viruses and fungi), parasites (e.g., hairworms and trematodes), and parasitoid wasps. In most cases, the mechanisms underlying host behavioral change remain relatively unclear. There is a growing body of literature linking alterations in immune signaling with neuron health, communication, and function; however, there is a paucity of data detailing the effects of altered neuroimmune signaling on insect neuron function and how glial cells may contribute toward neuron dysregulation. It is important to consider the potential impacts of altered neuroimmune communication on host behavior and reflect on its potential role as an important tool in the "neuro-engineer" toolkit. In this review, we examine what is known about the relationships between the insect immune and nervous systems. We highlight organisms that are able to influence insect behavior and discuss possible mechanisms of behavioral manipulation, including potentially dysregulated neuroimmune communication. We close by identifying opportunities for integrating research in insect innate immunity, glial cell physiology, and neurobiology in the investigation of behavioral manipulation.
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Affiliation(s)
- Colleen A. Mangold
- Department of Entomology, College of Agricultural Sciences, Pennsylvania State University, University Park, State College, PA 16802, USA;
- Center for Infectious Disease Dynamics, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - David P. Hughes
- Department of Entomology, College of Agricultural Sciences, Pennsylvania State University, University Park, State College, PA 16802, USA;
- Center for Infectious Disease Dynamics, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, State College, PA 16802, USA
- Department of Biology, Eberly College of Science, Pennsylvania State University, University Park, State College, PA 16802, USA
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9
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Guangming G, Junhua G, Chenchen Z, Yang M, Wei X. Neurexin and Neuroligins Maintain the Balance of Ghost and Satellite Boutons at the Drosophila Neuromuscular Junction. Front Neuroanat 2020; 14:19. [PMID: 32581727 PMCID: PMC7296126 DOI: 10.3389/fnana.2020.00019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/26/2020] [Indexed: 11/22/2022] Open
Abstract
Neurexins and neuroligins are common synaptic adhesion molecules that are associated with autism and interact with each other in the synaptic cleft. The Drosophila neuromuscular junction (NMJ) bouton is a well-known model system in neuroscience, and ghost and satellite boutons, respectively, indicate the poor development and overgrowth of the NMJ boutons. However, the Drosophila neurexin (DNrx) and Drosophila neuroligins (DNlgs) are mainly observed in type Ib boutons, indicating the ultrastructural and developmental phenotypes of the Drosophila NMJ. Here, we identified the ultrastructural and developmental features of ghost and satellite boutons by utilizing dneurexin (dnrx) and dneuroligins (dnlgs) fly mutants and other associated fly strains. Ghost boutons contain synaptic vesicles with multiple diameters but very rarely contain T-bar structures and swollen or thin subsynaptic reticulum (SSR) membranes. The muscle cell membrane is invaginated at different sites, stretches to the ghost bouton from different directions, forms several layers that enwrap the ghost bouton, and then branches into the complex SSR. Satellite boutons share a common SSR membrane and present either a typical profile in which a main bouton is encircled by small boutons or two atypical profiles in which the small boutons are grouped together or distributed in beads without a main bouton. Electron and confocal microscopy data showed that dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 mutations led to ghost boutons; the overexpression of dnrx, dnlg1, dnlg2, dnlg3, and dnlg4 led to satellite boutons; and the dnlg2;dnlg3 double mutation also led to satellite boutons. These results suggested that DNrx and DNlgs jointly maintain the development and function of NMJ boutons by regulating the balance of ghost and satellite boutons in Drosophila.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Geng Junhua
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, China.,The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Mou Yang
- School of Medicine, Southeast University, Nanjing, China
| | - Xie Wei
- The Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China.,Institute of Life Sciences, The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, China
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10
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Rossor AM, Sleigh JN, Groves M, Muntoni F, Reilly MM, Hoogenraad CC, Schiavo G. Loss of BICD2 in muscle drives motor neuron loss in a developmental form of spinal muscular atrophy. Acta Neuropathol Commun 2020; 8:34. [PMID: 32183910 PMCID: PMC7076953 DOI: 10.1186/s40478-020-00909-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 03/01/2020] [Indexed: 12/27/2022] Open
Abstract
Autosomal dominant missense mutations in BICD2 cause Spinal Muscular Atrophy Lower Extremity Predominant 2 (SMALED2), a developmental disease of motor neurons. BICD2 is a key component of the cytoplasmic dynein/dynactin motor complex, which in axons drives the microtubule-dependent retrograde transport of intracellular cargo towards the cell soma. Patients with pathological mutations in BICD2 develop malformations of cortical and cerebellar development similar to Bicd2 knockout (-/-) mice. In this study we sought to re-examine the motor neuron phenotype of conditional Bicd2-/- mice. Bicd2-/- mice show a significant reduction in the number of large calibre motor neurons of the L4 ventral root compared to wild type mice. Muscle-specific knockout of Bicd2 results in a similar reduction in L4 ventral axons comparable to global Bicd2-/- mice. Rab6, a small GTPase required for the sorting of exocytic vesicles from the Trans Golgi Network to the plasma membrane is a major binding partner of BICD2. We therefore examined the secretory pathway in SMALED2 patient fibroblasts and demonstrated that BICD2 is required for physiological flow of constitutive secretory cargoes from the Trans Golgi Network to the plasma membrane using a VSV-G reporter assay. Together, these data indicate that BICD2 loss from muscles is a major driver of non-cell autonomous pathology in the motor nervous system, which has important implications for future therapeutic approaches in SMALED2.
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Affiliation(s)
- Alexander M Rossor
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - James N Sleigh
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Michael Groves
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre and National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre, University College London Institute of Child Health, London, WC1N 1EH, UK
| | - Mary M Reilly
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK
| | - Casper C Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Giampietro Schiavo
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK.
- Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, London, WC1N 3BG, UK.
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11
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Li G, Forero MG, Wentzell JS, Durmus I, Wolf R, Anthoney NC, Parker M, Jiang R, Hasenauer J, Strausfeld NJ, Heisenberg M, Hidalgo A. A Toll-receptor map underlies structural brain plasticity. eLife 2020; 9:52743. [PMID: 32066523 PMCID: PMC7077983 DOI: 10.7554/elife.52743] [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: 10/14/2019] [Accepted: 02/12/2020] [Indexed: 12/28/2022] Open
Abstract
Experience alters brain structure, but the underlying mechanism remained unknown. Structural plasticity reveals that brain function is encoded in generative changes to cells that compete with destructive processes driving neurodegeneration. At an adult critical period, experience increases fiber number and brain size in Drosophila. Here, we asked if Toll receptors are involved. Tolls demarcate a map of brain anatomical domains. Focusing on Toll-2, loss of function caused apoptosis, neurite atrophy and impaired behaviour. Toll-2 gain of function and neuronal activity at the critical period increased cell number. Toll-2 induced cycling of adult progenitor cells via a novel pathway, that antagonized MyD88-dependent quiescence, and engaged Weckle and Yorkie downstream. Constant knock-down of multiple Tolls synergistically reduced brain size. Conditional over-expression of Toll-2 and wek at the adult critical period increased brain size. Through their topographic distribution, Toll receptors regulate neuronal number and brain size, modulating structural plasticity in the adult brain. Everything that you experience leaves its mark on your brain. When you learn something new, the neurons involved in the learning episode grow new projections and form new connections. Your brain may even produce new neurons. Physical exercise can induce similar changes, as can taking antidepressants. By contrast, stress, depression, ageing and disease can have the opposite effect, triggering neurons to break down and even die. The ability of the brain to change in response to experience is known as structural plasticity, and it is in a tug-of-war with processes that drive neurodegeneration. Structural plasticity occurs in other species too: for example, it was described in the fruit fly more than a quarter of a century ago. Yet, the molecular mechanisms underlying structural plasticity remain unclear. Li et al. now show that, in fruit flies, this plasticity involves Toll receptors, a family of proteins present in the brain but best known for their role in the immune system. Fruit flies have nine different Toll receptors, the most abundant being Toll-2. When activated, these proteins can trigger a series of molecular events in a cell. Li et al. show that increasing the amount of Toll-2 in the fly brain makes the brain produce new neurons. Activating neurons in a brain region has the same effect, and this increase in neuron number also depends on Toll-2. By contrast, reducing the amount of Toll-2 causes neurons to lose their projections and connections, and to die, and impairs fly behaviour. Li et al. also show that each Toll receptor has a unique distribution across the fly brain. Different types of experiences activate different brain regions, and therefore different Toll receptors. These go on to trigger a common molecular cascade, but they modulate it such as to result in distinct outcomes. By working together in different combinations, Toll receptors can promote either the death or survival of neurons, and they can also drive specific brain cells to remain dormant or to produce new neurons. By revealing how experience changes the brain, Li et al. provide clues to the way neurons work and form; these findings may also help to find new treatments for disorders that change brain structure, such as certain psychiatric conditions. Toll-like receptors in humans could thus represent a promising new target for drug discovery.
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Affiliation(s)
- Guiyi Li
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Manuel G Forero
- Facultad de Ingeniería, Universidad de Ibagué, Ibagué, Colombia
| | - Jill S Wentzell
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Ilgim Durmus
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Reinhard Wolf
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Niki C Anthoney
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Mieczyslaw Parker
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Ruiying Jiang
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jacob Hasenauer
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Nicholas James Strausfeld
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Neuroscience, University of Arizona College of Science, Tucson, United States
| | - Martin Heisenberg
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Alicia Hidalgo
- Neurodevelopment Lab, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
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12
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Mishra-Gorur K, Li D, Ma X, Yarman Y, Xue L, Xu T. Spz/Toll-6 signal guides organotropic metastasis in Drosophila. Dis Model Mech 2019; 12:dmm039727. [PMID: 31477571 PMCID: PMC6826028 DOI: 10.1242/dmm.039727] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 08/20/2019] [Indexed: 12/23/2022] Open
Abstract
Targeted cell migration plays important roles in developmental biology and disease processes, including in metastasis. Drosophila tumors exhibit traits characteristic of human cancers, providing a powerful model to study developmental and cancer biology. We now find that cells derived from Drosophila eye-disc tumors also display organ-specific metastasis, invading receptive organs but not wing disc. Toll receptors are known to affect innate immunity and the tumor inflammatory microenvironment by modulating the NF-κB pathway. Our RNA interference (RNAi) screen and genetic analyses show that Toll-6 is required for migration and invasion of the tumor cells. Further, receptive organs express Toll ligands [Spätzle (Spz) family molecules], and ectopic Spz expression renders the wing disc receptive to metastasis. Finally, Toll-6 promotes metastasis by activating JNK signaling, a key regulator of cell migration. Hence, we report Toll-6 and Spz as a new pair of guidance molecules mediating organ-specific metastatic behavior and highlight a novel signaling mechanism for Toll-family receptors.
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Affiliation(s)
- Ketu Mishra-Gorur
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Daming Li
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Xianjue Ma
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
- School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China
| | - Yanki Yarman
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Lei Xue
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
- Shanghai Key Laboratory for Signaling and Diseases, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Tian Xu
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, CT 06519, USA
- School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China
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13
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The Role of Apoptotic Signaling in Axon Guidance. J Dev Biol 2018; 6:jdb6040024. [PMID: 30340315 PMCID: PMC6316149 DOI: 10.3390/jdb6040024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/16/2018] [Accepted: 10/16/2018] [Indexed: 12/28/2022] Open
Abstract
Navigating growth cones are exposed to multiple signals simultaneously and have to integrate competing cues into a coherent navigational response. Integration of guidance cues is traditionally thought to occur at the level of cytoskeletal dynamics. Drosophila studies indicate that cells exhibit a low level of continuous caspase protease activation, and that axon guidance cues can activate or suppress caspase activity. We base a model for axon guidance on these observations. By analogy with other systems in which caspase signaling has non-apoptotic functions, we propose that caspase signaling can either reinforce repulsion or negate attraction in response to external guidance cues by cleaving cytoskeletal proteins. Over the course of an entire trajectory, incorrectly navigating axons may pass the threshold for apoptosis and be eliminated, whereas axons making correct decisions will survive. These observations would also explain why neurotrophic factors can act as axon guidance cues and why axon guidance systems such as Slit/Robo signaling may act as tumor suppressors in cancer.
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14
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Shmueli A, Shalit T, Okun E, Shohat-Ophir G. The Toll Pathway in the Central Nervous System of Flies and Mammals. Neuromolecular Med 2018; 20:419-436. [PMID: 30276585 DOI: 10.1007/s12017-018-8515-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/26/2018] [Indexed: 12/20/2022]
Abstract
Toll receptors, first identified to regulate embryogenesis and immune responses in the adult fly and subsequently defined as the principal sensors of infection in mammals, are increasingly appreciated for their impact on the homeostasis of the central as well as the peripheral nervous systems. Whereas in the context of immunity, the fly Toll and the mammalian TLR pathways have been researched in parallel, the expression pattern and functionality have largely been researched disparately. Herein, we provide data on the expression pattern of the Toll homologues, signaling components, and downstream effectors in ten different cell populations of the adult fly central nervous system (CNS). We have compared the expression of the different Toll pathways in the fly to the expression of TLRs in the mouse brain and discussed the implications with respect to commonalities, differences, and future perspectives.
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Affiliation(s)
- Anat Shmueli
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Tali Shalit
- The Mantoux Bioinformatics institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Okun
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel.
- The Paul Feder Laboratory on Alzheimer's Disease Research, Ramat-Gan, Israel.
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Building 901, room 315, Ramat-Gan, 5290000, Israel.
| | - Galit Shohat-Ophir
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
- The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel.
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15
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Coutinho-Budd JC, Sheehan AE, Freeman MR. The secreted neurotrophin Spätzle 3 promotes glial morphogenesis and supports neuronal survival and function. Genes Dev 2017; 31:2023-2038. [PMID: 29138279 PMCID: PMC5733495 DOI: 10.1101/gad.305888.117] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/20/2017] [Indexed: 10/27/2022]
Abstract
Most glial functions depend on establishing intimate morphological relationships with neurons. Significant progress has been made in understanding neuron-glia signaling at synaptic and axonal contacts, but how glia support neuronal cell bodies is unclear. Here we explored the growth and functions of Drosophila cortex glia (which associate almost exclusively with neuronal cell bodies) to understand glia-soma interactions. We show that cortex glia tile with one another and with astrocytes to establish unique central nervous system (CNS) spatial domains that actively restrict glial growth, and selective ablation of cortex glia causes animal lethality. In an RNAi-based screen, we identified αSNAP (soluble NSF [N-ethylmalemeide-sensitive factor] attachment protein α) and several components of vesicle fusion and recycling machinery as essential for the maintenance of cortex glial morphology and continued contact with neurons. Interestingly, loss of the secreted neurotrophin Spätzle 3 (Spz3) phenocopied αSNAP phenotypes, which included loss of glial ensheathment of neuron cell bodies, increased neuronal cell death, and defects in animal behavior. Rescue experiments suggest that Spz3 can exert these effects only over very short distances. This work identifies essential roles for glial ensheathment of neuronal cell bodies in CNS homeostasis as well as Spz3 as a novel signaling factor required for maintenance of cortex glial morphology and neuron-glia contact.
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Affiliation(s)
- Jaeda C Coutinho-Budd
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Amy E Sheehan
- Vollum Institute, Oregon Health and Sciences University, Portland, Oregon 97239, USA
| | - Marc R Freeman
- Vollum Institute, Oregon Health and Sciences University, Portland, Oregon 97239, USA
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16
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Ulian-Benitez S, Bishop S, Foldi I, Wentzell J, Okenwa C, Forero MG, Zhu B, Moreira M, Phizacklea M, McIlroy G, Li G, Gay NJ, Hidalgo A. Kek-6: A truncated-Trk-like receptor for Drosophila neurotrophin 2 regulates structural synaptic plasticity. PLoS Genet 2017; 13:e1006968. [PMID: 28846707 PMCID: PMC5591008 DOI: 10.1371/journal.pgen.1006968] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 09/08/2017] [Accepted: 08/08/2017] [Indexed: 01/19/2023] Open
Abstract
Neurotrophism, structural plasticity, learning and long-term memory in mammals critically depend on neurotrophins binding Trk receptors to activate tyrosine kinase (TyrK) signaling, but Drosophila lacks full-length Trks, raising the question of how these processes occur in the fly. Paradoxically, truncated Trk isoforms lacking the TyrK predominate in the adult human brain, but whether they have neuronal functions independently of full-length Trks is unknown. Drosophila has TyrK-less Trk-family receptors, encoded by the kekkon (kek) genes, suggesting that evolutionarily conserved functions for this receptor class may exist. Here, we asked whether Keks function together with Drosophila neurotrophins (DNTs) at the larval glutamatergic neuromuscular junction (NMJ). We tested the eleven LRR and Ig-containing (LIG) proteins encoded in the Drosophila genome for expression in the central nervous system (CNS) and potential interaction with DNTs. Kek-6 is expressed in the CNS, interacts genetically with DNTs and can bind DNT2 in signaling assays and co-immunoprecipitations. Ligand binding is promiscuous, as Kek-6 can also bind DNT1, and Kek-2 and Kek-5 can also bind DNT2. In vivo, Kek-6 is found presynaptically in motoneurons, and DNT2 is produced by the muscle to function as a retrograde factor at the NMJ. Kek-6 and DNT2 regulate NMJ growth and synaptic structure. Evidence indicates that Kek-6 does not antagonise the alternative DNT2 receptor Toll-6. Instead, Kek-6 and Toll-6 interact physically, and together regulate structural synaptic plasticity and homeostasis. Using pull-down assays, we identified and validated CaMKII and VAP33A as intracellular partners of Kek-6, and show that they regulate NMJ growth and active zone formation downstream of DNT2 and Kek-6. The synaptic functions of Kek-6 could be evolutionarily conserved. This raises the intriguing possibility that a novel mechanism of structural synaptic plasticity involving truncated Trk-family receptors independently of TyrK signaling may also operate in the human brain. A long-standing paradox had been to explain how brain structural plasticity, learning and long-term memory might occur in Drosophila in the absence of canonical Trk receptors for neurotrophin (NT) ligands. NTs link structure and function in the brain enabling adjustments in cell number, dendritic, axonal and synaptic patterns, in response to neuronal activity. These events are essential for brain development, learning and long-term memory, and are thought to depend on the tyrosine-kinase function of the NT Trk receptors. However, paradoxically, the most abundant Trk isoforms in the adult human brain lack the tyrosine kinase, and their neuronal function is unknown. Remarkably, Drosophila has kinase-less receptors of the Trk family encoded by the kekkon (kek) genes, suggesting that deep evolutionary functional conservation for this receptor class could be unveiled. Here, we show that Kek-6 is a receptor for Drosophila neurotrophin 2 (DNT2) that regulates structural synaptic plasticity via CaMKII and VAP33A. The latter are well-known factors regulating synaptic structure and plasticity and vesicle release. Furthemore, Kek-6 cooperates with the alternative DNT2 receptor Toll-6, and their concerted functions are required to regulate structural homeostasis at the NMJ. Our findings suggest that in mammals truncated Trk-family receptors could also have synaptic functions in neurons independently of Tyrosine kinase signaling. This might reveal a novel mechanism of brain plasticity, with important implications for understanding also the human brain, in health and disease.
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Affiliation(s)
- Suzana Ulian-Benitez
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Simon Bishop
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Istvan Foldi
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Jill Wentzell
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Chinenye Okenwa
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | | | - Bangfu Zhu
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Marta Moreira
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Mark Phizacklea
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Graham McIlroy
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Guiyi Li
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Nicholas J. Gay
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Alicia Hidalgo
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
- * E-mail:
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17
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Saburova EA, Vasiliev AN, Kravtsova VV, Ryabova EV, Zefirov AL, Bolshakova OI, Sarantseva SV, Krivoi II. Human APP Gene Expression Alters Active Zone Distribution and Spontaneous Neurotransmitter Release at the Drosophila Larval Neuromuscular Junction. Neural Plast 2017; 2017:9202584. [PMID: 28770114 PMCID: PMC5523229 DOI: 10.1155/2017/9202584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/07/2017] [Indexed: 12/11/2022] Open
Abstract
This study provides further insight into the molecular mechanisms that control neurotransmitter release. Experiments were performed on larval neuromuscular junctions of transgenic Drosophila melanogaster lines with different levels of human amyloid precursor protein (APP) production. To express human genes in motor neurons of Drosophila, the UAS-GAL4 system was used. Human APP gene expression increased the number of synaptic boutons per neuromuscular junction. The total number of active zones, detected by Bruchpilot protein puncta distribution, remained unchanged; however, the average number of active zones per bouton decreased. These disturbances were accompanied by a decrease in frequency of miniature excitatory junction potentials without alteration in random nature of spontaneous quantal release. Similar structural and functional changes were observed with co-overexpression of human APP and β-secretase genes. In Drosophila line with expression of human amyloid-β42 peptide itself, parameters analyzed did not differ from controls, suggesting the specificity of APP effects. These results confirm the involvement of APP in synaptogenesis and provide evidence to suggest that human APP overexpression specifically disturbs the structural and functional organization of active zone and results in altered Bruchpilot distribution and lowered probability of spontaneous neurotransmitter release.
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Affiliation(s)
- Ekaterina A. Saburova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Alexander N. Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Violetta V. Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Elena V. Ryabova
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Andrey L. Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Olga I. Bolshakova
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Svetlana V. Sarantseva
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Igor I. Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
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18
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Castells-Nobau A, Nijhof B, Eidhof I, Wolf L, Scheffer-de Gooyert JM, Monedero I, Torroja L, van der Laak JAWM, Schenck A. Two Algorithms for High-throughput and Multi-parametric Quantification of Drosophila Neuromuscular Junction Morphology. J Vis Exp 2017. [PMID: 28518121 PMCID: PMC5607876 DOI: 10.3791/55395] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Synaptic morphology is tightly related to synaptic efficacy, and in many cases morphological synapse defects ultimately lead to synaptic malfunction. The Drosophila larval neuromuscular junction (NMJ), a well-established model for glutamatergic synapses, has been extensively studied for decades. Identification of mutations causing NMJ morphological defects revealed a repertoire of genes that regulate synapse development and function. Many of these were identified in large-scale studies that focused on qualitative approaches to detect morphological abnormalities of the Drosophila NMJ. A drawback of qualitative analyses is that many subtle players contributing to NMJ morphology likely remain unnoticed. Whereas quantitative analyses are required to detect the subtler morphological differences, such analyses are not yet commonly performed because they are laborious. This protocol describes in detail two image analysis algorithms "Drosophila NMJ Morphometrics" and "Drosophila NMJ Bouton Morphometrics", available as Fiji-compatible macros, for quantitative, accurate and objective morphometric analysis of the Drosophila NMJ. This methodology is developed to analyze NMJ terminals immunolabeled with the commonly used markers Dlg-1 and Brp. Additionally, its wider application to other markers such as Hrp, Csp and Syt is presented in this protocol. The macros are able to assess nine morphological NMJ features: NMJ area, NMJ perimeter, number of boutons, NMJ length, NMJ longest branch length, number of islands, number of branches, number of branching points and number of active zones in the NMJ terminal.
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Affiliation(s)
- Anna Castells-Nobau
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center
| | - Bonnie Nijhof
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center
| | - Ilse Eidhof
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center
| | - Louis Wolf
- Microscopical Imaging Centre (MIC), Radboud University Medical Center
| | - Jolanda M Scheffer-de Gooyert
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center
| | - Ignacio Monedero
- Department of Biology, Universidad Autónoma de Madrid; Department of Clinical and Experimental Medicine, Linköping University
| | - Laura Torroja
- Department of Biology, Universidad Autónoma de Madrid
| | - Jeroen A W M van der Laak
- Microscopical Imaging Centre (MIC), Radboud University Medical Center; Department of Pathology, Radboud University Medical Center
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center;
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19
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Foldi I, Anthoney N, Harrison N, Gangloff M, Verstak B, Nallasivan MP, AlAhmed S, Zhu B, Phizacklea M, Losada-Perez M, Moreira M, Gay NJ, Hidalgo A. Three-tier regulation of cell number plasticity by neurotrophins and Tolls in Drosophila. J Cell Biol 2017; 216:1421-1438. [PMID: 28373203 PMCID: PMC5412559 DOI: 10.1083/jcb.201607098] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/20/2016] [Accepted: 02/16/2017] [Indexed: 02/06/2023] Open
Abstract
A three-tier mechanism involving distinct neurotrophin family ligand forms, different Toll receptors, and different adaptors regulates both cell survival and death. This rich mechanism confers cell number plasticity and could underlie structural plasticity in the nervous system and structural integrity, homeostasis, and regeneration in wider contexts. Cell number plasticity is coupled to circuitry in the nervous system, adjusting cell mass to functional requirements. In mammals, this is achieved by neurotrophin (NT) ligands, which promote cell survival via their Trk and p75NTR receptors and cell death via p75NTR and Sortilin. Drosophila NTs (DNTs) bind Toll receptors instead to promote neuronal survival, but whether they can also regulate cell death is unknown. In this study, we show that DNTs and Tolls can switch from promoting cell survival to death in the central nervous system (CNS) via a three-tier mechanism. First, DNT cleavage patterns result in alternative signaling outcomes. Second, different Tolls can preferentially promote cell survival or death. Third, distinct adaptors downstream of Tolls can drive either apoptosis or cell survival. Toll-6 promotes cell survival via MyD88–NF-κB and cell death via Wek-Sarm-JNK. The distribution of adaptors changes in space and time and may segregate to distinct neural circuits. This novel mechanism for CNS cell plasticity may operate in wider contexts.
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Affiliation(s)
- Istvan Foldi
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Niki Anthoney
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Neale Harrison
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Monique Gangloff
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, England, UK
| | - Brett Verstak
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, England, UK
| | | | - Samaher AlAhmed
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Bangfu Zhu
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Mark Phizacklea
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Maria Losada-Perez
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Marta Moreira
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
| | - Nicholas J Gay
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, England, UK
| | - Alicia Hidalgo
- NeuroDevelopment Group, School of Biosciences, University of Birmingham, Birmingham B15 2TT, England, UK
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20
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Yuan K, Yuan FH, Weng SP, He JG, Chen YH. Identification and functional characterization of a novel Spätzle gene in Litopenaeus vannamei. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 68:46-57. [PMID: 27884706 DOI: 10.1016/j.dci.2016.11.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 11/18/2016] [Accepted: 11/18/2016] [Indexed: 06/06/2023]
Abstract
Shrimp innate immunity is the first line of resistance against pathogenic bacteria. The Toll-like receptor (TLR)-NF-κB pathway is vital in this immunity process. In this study, a novel Spätzle gene (LvSpz4) of Litopenaeus vannamei was cloned and functionally characterized. The open reading frame of LvSpz4 was 918 bp, which encoded a putative protein with 305 amino acids. LvSpz4 was most expressed in the gills of L. vannamei. This expression was induced by Vibrio alginolyticus or Staphylococcus aureus infection or lipopolysaccharide stimulation. The reporter gene assay showed that LvSpz4 could activate the promoters of Pen4, Drs, AttA, Mtk, and white spot syndrome virus immediate early gene1 in Drosophila Schneider 2 (S2) cells. Knockdown LvSpz4 increased the cumulative mortality of L. vannamei upon V. alginolyticus infection. The unfolded protein response (UPR) induced the expression of LvSpz4 in L. vannamei. Moreover, the promoter of LvSpz4 was activated by L. vannamei X-Box binding protein 1 and activating transcription factor 4 in S2 cells. These results suggested that LvSpz4 was involved in L. vannamei innate immunity and caused the crosstalk between the TLR-NF-κB pathway and UPR.
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Affiliation(s)
- Kai Yuan
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Feng-Hua Yuan
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Shao-Ping Weng
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Jian-Guo He
- Key Laboratory of Marine Resources and Coastal Engineering in Guangdong Province, South China Sea Bio-Resource Exploitation and Protection Collaborative Innovation Center (SCS-REPIC), School of Marine Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; School of Life Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China
| | - Yi-Hong Chen
- Key Laboratory of Marine Resources and Coastal Engineering in Guangdong Province, South China Sea Bio-Resource Exploitation and Protection Collaborative Innovation Center (SCS-REPIC), School of Marine Sciences, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China; State Key Laboratory for Biocontrol, MOE Key Laboratory of Aquatic Product Safety, Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, 135 Xingang Road West, Guangzhou 510275, PR China.
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21
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Celona B, Dollen JV, Vatsavayai SC, Kashima R, Johnson JR, Tang AA, Hata A, Miller BL, Huang EJ, Krogan NJ, Seeley WW, Black BL. Suppression of C9orf72 RNA repeat-induced neurotoxicity by the ALS-associated RNA-binding protein Zfp106. eLife 2017; 6. [PMID: 28072389 PMCID: PMC5283830 DOI: 10.7554/elife.19032] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 01/02/2017] [Indexed: 12/13/2022] Open
Abstract
Expanded GGGGCC repeats in the first intron of the C9orf72 gene represent the most common cause of familial amyotrophic lateral sclerosis (ALS), but the mechanisms underlying repeat-induced disease remain incompletely resolved. One proposed gain-of-function mechanism is that repeat-containing RNA forms aggregates that sequester RNA binding proteins, leading to altered RNA metabolism in motor neurons. Here, we identify the zinc finger protein Zfp106 as a specific GGGGCC RNA repeat-binding protein, and using affinity purification-mass spectrometry, we show that Zfp106 interacts with multiple other RNA binding proteins, including the ALS-associated factors TDP-43 and FUS. We also show that Zfp106 knockout mice develop severe motor neuron degeneration, which can be suppressed by transgenic restoration of Zfp106 specifically in motor neurons. Finally, we show that Zfp106 potently suppresses neurotoxicity in a Drosophila model of C9orf72 ALS. Thus, these studies identify Zfp106 as an RNA binding protein with important implications for ALS. DOI:http://dx.doi.org/10.7554/eLife.19032.001 Molecules of ribonucleic acid (or RNA for short) have many roles in cells, including acting as templates to make proteins. RNA is made of building blocks called nucleotides that are assembled to form strands. The precise order of the nucleotides in an RNA molecule can have a dramatic effect on the role that RNA plays in the body. For example, amyotrophic lateral sclerosis (ALS) is a deadly disease caused by the gradual loss of the nerve cells that control muscle (known as motor neurons). The most common cause of inherited ALS is a genetic mutation that results in some RNA molecules having many more copies of a simple six nucleotide sequence known as GGGGCC than normal cells. RNA molecules with these “GGGGCC repeats” form clumps in motor neurons. The clumps of RNA molecules also contain proteins, but the identities of these RNA-binding proteins and the roles they play in ALS remain largely unknown. Celona et al. have now identified a new RNA-binding protein called Zfp106, which binds specifically to GGGGCC repeats in mice and fruit flies. Removing the gene that encodes Zfp106 from mice causes the mice to develop ALS. On the other hand, restoring Zfp106 only to the motor neurons of these mutant mice prevents the mice from developing disease. This suggests that Zfp106’s role is specific to motor neurons. Indeed, fruit flies that have too many copies of GGGGCC develop severe symptoms reminiscent of ALS. Introducing a mammalian version of Zfp106 into these flies prevents them from developing the disease. The findings of Celona et al. suggest that Zfp106 might be a potential new drug target for treating ALS in humans. The next step following this work will be to find out exactly how Zfp106 regulates normal cellular processes by binding to RNA and how it suppresses ALS-like disease by binding to GGGGCC RNA-repeats. DOI:http://dx.doi.org/10.7554/eLife.19032.002
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Affiliation(s)
- Barbara Celona
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - John von Dollen
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Sarat C Vatsavayai
- Department of Neurology, University of California, San Francisco, San Francisco, United States
| | - Risa Kashima
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Jeffrey R Johnson
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Amy A Tang
- Department of Pathology, University of California, San Francisco, San Francisco, United States
| | - Akiko Hata
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Bruce L Miller
- Department of Neurology, University of California, San Francisco, San Francisco, United States
| | - Eric J Huang
- Department of Pathology, University of California, San Francisco, San Francisco, United States
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - William W Seeley
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Department of Pathology, University of California, San Francisco, San Francisco, United States
| | - Brian L Black
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
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22
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Hussein NA, Delaney TL, Tounsel BL, Liebl FLW. The Extracellular-Regulated Kinase Effector Lk6 is Required for Glutamate Receptor Localization at the Drosophila Neuromuscular Junction. J Exp Neurosci 2016; 10:77-91. [PMID: 27199570 PMCID: PMC4866800 DOI: 10.4137/jen.s32840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 11/16/2022] Open
Abstract
The proper localization and synthesis of postsynaptic glutamate receptors are essential for synaptic plasticity. Synaptic translation initiation is thought to occur via the target of rapamycin (TOR) and mitogen-activated protein kinase signal-integrating kinase (Mnk) signaling pathways, which is downstream of extracellular-regulated kinase (ERK). We used the model glutamatergic synapse, the Drosophila neuromuscular junction, to better understand the roles of the Mnk and TOR signaling pathways in synapse development. These synapses contain non-NMDA receptors that are most similar to AMPA receptors. Our data show that Lk6, the Drosophila homolog of Mnk1 and Mnk2, is required in either presynaptic neurons or postsynaptic muscle for the proper localization of the GluRIIA glutamate receptor subunit. Lk6 may signal through eukaryotic initiation factor (eIF) 4E to regulate the synaptic levels of GluRIIA as either interfering with eIF4E binding to eIF4G or expression of a nonphosphorylatable isoform of eIF4E resulted in a significant reduction in GluRIIA at the synapse. We also find that Lk6 and TOR may independently regulate synaptic levels of GluRIIA.
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Affiliation(s)
- Nizar A Hussein
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Taylor L Delaney
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Brittany L Tounsel
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, IL, USA
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23
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Nijhof B, Castells-Nobau A, Wolf L, Scheffer-de Gooyert JM, Monedero I, Torroja L, Coromina L, van der Laak JAWM, Schenck A. A New Fiji-Based Algorithm That Systematically Quantifies Nine Synaptic Parameters Provides Insights into Drosophila NMJ Morphometry. PLoS Comput Biol 2016; 12:e1004823. [PMID: 26998933 PMCID: PMC4801422 DOI: 10.1371/journal.pcbi.1004823] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/19/2016] [Indexed: 11/20/2022] Open
Abstract
The morphology of synapses is of central interest in neuroscience because of the intimate relation with synaptic efficacy. Two decades of gene manipulation studies in different animal models have revealed a repertoire of molecules that contribute to synapse development. However, since such studies often assessed only one, or at best a few, morphological features at a given synapse, it remained unaddressed how different structural aspects relate to one another. Furthermore, such focused and sometimes only qualitative approaches likely left many of the more subtle players unnoticed. Here, we present the image analysis algorithm 'Drosophila_NMJ_Morphometrics', available as a Fiji-compatible macro, for quantitative, accurate and objective synapse morphometry of the Drosophila larval neuromuscular junction (NMJ), a well-established glutamatergic model synapse. We developed this methodology for semi-automated multiparametric analyses of NMJ terminals immunolabeled for the commonly used markers Dlg1 and Brp and showed that it also works for Hrp, Csp and Syt. We demonstrate that gender, genetic background and identity of abdominal body segment consistently and significantly contribute to variability in our data, suggesting that controlling for these parameters is important to minimize variability in quantitative analyses. Correlation and principal component analyses (PCA) were performed to investigate which morphometric parameters are inter-dependent and which ones are regulated rather independently. Based on nine acquired parameters, we identified five morphometric groups: NMJ size, geometry, muscle size, number of NMJ islands and number of active zones. Based on our finding that the parameters of the first two principal components hardly correlated with each other, we suggest that different molecular processes underlie these two morphometric groups. Our study sets the stage for systems morphometry approaches at the well-studied Drosophila NMJ.
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Affiliation(s)
- Bonnie Nijhof
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anna Castells-Nobau
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Louis Wolf
- Microscopical Imaging Centre (MIC), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jolanda M. Scheffer-de Gooyert
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ignacio Monedero
- Department of Biology, Universidad Autónoma de Madrid, Madrid, Spain
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Laura Torroja
- Department of Biology, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lluis Coromina
- Research Group on Statistics, Econometrics and Health (GRECS) and CIBER of Epidemiology and Public Health (CIBERESP), University of Girona, Girona, Spain
| | - Jeroen A. W. M. van der Laak
- Microscopical Imaging Centre (MIC), Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
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24
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Nie Y, Ip YT. How Toll Met Hippo. Dev Cell 2016; 36:246-8. [PMID: 26859349 DOI: 10.1016/j.devcel.2016.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Toll and Hippo are two seemingly disparate pathways that regulate innate immunity and tissue growth, respectively. Reporting recently in Cell, Liu et al. (2016) tie them together by demonstrating that microbial infection activates Toll, which then signals to both pathways to modulate the antimicrobial response.
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Affiliation(s)
- Yingchao Nie
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Y Tony Ip
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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25
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Deshpande M, Rodal AA. The Crossroads of Synaptic Growth Signaling, Membrane Traffic and Neurological Disease: Insights from Drosophila. Traffic 2015; 17:87-101. [PMID: 26538429 DOI: 10.1111/tra.12345] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/29/2015] [Accepted: 10/29/2015] [Indexed: 12/13/2022]
Abstract
Neurons require target-derived autocrine and paracrine growth factors to maintain proper identity, innervation, homeostasis and survival. Neuronal growth factor signaling is highly dependent on membrane traffic, both for the packaging and release of the growth factors themselves, and for regulation of intracellular signaling by their transmembrane receptors. Here, we review recent findings from the Drosophila larval neuromuscular junction (NMJ) that illustrate how specific steps of intracellular traffic and inter-organelle interactions impinge on signaling, particularly in the bone morphogenic protein, Wingless and c-Jun-activated kinase pathways, regulating elaboration and stability of NMJ arbors, construction of synapses and synaptic transmission and homeostasis. These membrane trafficking and signaling pathways have been implicated in human motor neuron diseases including amyotrophic lateral sclerosis and hereditary spastic paraplegia, highlighting their importance for neuronal health and survival.
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Affiliation(s)
| | - Avital A Rodal
- Department of Biology, Brandeis University, Waltham, MA, USA
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26
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Harris KP, Littleton JT. Transmission, Development, and Plasticity of Synapses. Genetics 2015; 201:345-75. [PMID: 26447126 PMCID: PMC4596655 DOI: 10.1534/genetics.115.176529] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/28/2015] [Indexed: 01/03/2023] Open
Abstract
Chemical synapses are sites of contact and information transfer between a neuron and its partner cell. Each synapse is a specialized junction, where the presynaptic cell assembles machinery for the release of neurotransmitter, and the postsynaptic cell assembles components to receive and integrate this signal. Synapses also exhibit plasticity, during which synaptic function and/or structure are modified in response to activity. With a robust panel of genetic, imaging, and electrophysiology approaches, and strong evolutionary conservation of molecular components, Drosophila has emerged as an essential model system for investigating the mechanisms underlying synaptic assembly, function, and plasticity. We will discuss techniques for studying synapses in Drosophila, with a focus on the larval neuromuscular junction (NMJ), a well-established model glutamatergic synapse. Vesicle fusion, which underlies synaptic release of neurotransmitters, has been well characterized at this synapse. In addition, studies of synaptic assembly and organization of active zones and postsynaptic densities have revealed pathways that coordinate those events across the synaptic cleft. We will also review modes of synaptic growth and plasticity at the fly NMJ, and discuss how pre- and postsynaptic cells communicate to regulate plasticity in response to activity.
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Affiliation(s)
- Kathryn P Harris
- Department of Biology and Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - J Troy Littleton
- Department of Biology and Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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27
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28
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Lim JY, Reighard CP, Crowther DC. The pro-domains of neurotrophins, including BDNF, are linked to Alzheimer's disease through a toxic synergy with Aβ. Hum Mol Genet 2015; 24:3929-38. [PMID: 25954034 PMCID: PMC4476443 DOI: 10.1093/hmg/ddv130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/08/2015] [Indexed: 12/27/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) has a crucial role in learning and memory by promoting neuronal survival and modulating synaptic connectivity. BDNF levels are lower in the brains of individuals with Alzheimer's disease (AD), suggesting a pathogenic involvement. The Drosophila orthologue of BDNF is the highly conserved Neurotrophin 1 (DNT1). BDNF and DNT1 have the same overall protein structure and can be cleaved, resulting in the conversion of a full-length polypeptide into separate pro- and mature-domains. While the BDNF mature-domain is neuroprotective, the role of the pro-domain is less clear. In flies and mammalian cells, we have identified a synergistic toxic interaction between the amyloid-β peptide (Aβ1–42) and the pro-domains of both DNT1 and BDNF. Specifically, we show that DNT1 pro-domain acquires a neurotoxic activity in the presence of Aβ1–42. In contrast, DNT1 mature-domain is protective against Aβ1–42 toxicity. Likewise, in SH-SY5Y cell culture, BDNF pro-domain is toxic only in the presence of Aβ1–42. Western blots indicate that this synergistic interaction likely results from the Aβ1–42-induced upregulation of the BDNF pro-domain receptor p75NTR. The clinical relevance of these findings is underlined by a greater than thirty fold increase in the ratio of BDNF pro- to mature-domains in the brains of individuals with AD. This unbalanced BDNF pro:mature-domain ratio in patients represents a possible biomarker of AD and may offer a target for therapeutic intervention.
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Affiliation(s)
- Jung Yeon Lim
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Charles P Reighard
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK and
| | - Damian C Crowther
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK, MedImmune Limited, Aaron Klug Building, Granta Park, Cambridge CB21 6GH, UK
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29
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Lee YM, Sun YH. Maintenance of glia in the optic lamina is mediated by EGFR signaling by photoreceptors in adult Drosophila. PLoS Genet 2015; 11:e1005187. [PMID: 25909451 PMCID: PMC4409299 DOI: 10.1371/journal.pgen.1005187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/31/2015] [Indexed: 01/13/2023] Open
Abstract
The late onset of neurodegeneration in humans indicates that the survival and function of cells in the nervous system must be maintained throughout adulthood. In the optic lamina of the adult Drosophila, the photoreceptor axons are surrounded by multiple types of glia. We demonstrated that the adult photoreceptors actively contribute to glia maintenance in their target field within the optic lamina. This effect is dependent on the epidermal growth factor receptor (EGFR) ligands produced by the R1-6 photoreceptors and transported to the optic lamina to act on EGFR in the lamina glia. EGFR signaling is necessary and sufficient to act in a cell-autonomous manner in the lamina glia. Our results suggest that EGFR signaling is required for the trafficking of the autophagosome/endosome to the lysosome. The loss of EGFR signaling results in cell degeneration most likely because of the accumulation of autophagosomes. Our findings provide in vivo evidence for the role of adult neurons in the maintenance of glia and a novel role for EGFR signaling in the autophagic flux. Degeneration of the nervous system can be viewed as a failure to maintain cell survival or function in the nervous system. The late onset of neurodegeneration in humans indicates that the cell survival in the nervous system must be maintained throughout our lives. Neuronal survival is maintained by neurotrophic factors in adults; however, it is unclear whether glia survival is also maintained throughout adulthood. Here, we use the Drosophila visual system as a model to address the role played by adult neurons for the active maintenance of glia. We demonstrated that the adult photoreceptors secrete a signaling molecule, which is transported to the brain to act on the lamina glia and maintain its integrity. When this signaling pathway is blocked, the lamina glia undergoes a progressive and irreversible degeneration. The primary defect occurs in the trafficking from the late endosome and autophagosome to the lysosome. This defect leads to an accumulation of autophagosomes and subsequent cell degeneration as a result of autophagy. Our findings provide in vivo evidence for a novel aspect of the neuron-glia interaction and a novel role for EGFR signaling in regulating the maintenance and degeneration of the nervous system.
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Affiliation(s)
- Yuan-Ming Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Y. Henry Sun
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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30
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Ferreira ÁG, Naylor H, Esteves SS, Pais IS, Martins NE, Teixeira L. The Toll-dorsal pathway is required for resistance to viral oral infection in Drosophila. PLoS Pathog 2014; 10:e1004507. [PMID: 25473839 PMCID: PMC4256459 DOI: 10.1371/journal.ppat.1004507] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 10/08/2014] [Indexed: 01/22/2023] Open
Abstract
Pathogen entry route can have a strong impact on the result of microbial infections in different hosts, including insects. Drosophila melanogaster has been a successful model system to study the immune response to systemic viral infection. Here we investigate the role of the Toll pathway in resistance to oral viral infection in D. melanogaster. We show that several Toll pathway components, including Spätzle, Toll, Pelle and the NF-kB-like transcription factor Dorsal, are required to resist oral infection with Drosophila C virus. Furthermore, in the fat body Dorsal is translocated from the cytoplasm to the nucleus and a Toll pathway target gene reporter is upregulated in response to Drosophila C Virus infection. This pathway also mediates resistance to several other RNA viruses (Cricket paralysis virus, Flock House virus, and Nora virus). Compared with control, viral titres are highly increased in Toll pathway mutants. The role of the Toll pathway in resistance to viruses in D. melanogaster is restricted to oral infection since we do not observe a phenotype associated with systemic infection. We also show that Wolbachia and other Drosophila-associated microbiota do not interact with the Toll pathway-mediated resistance to oral infection. We therefore identify the Toll pathway as a new general inducible pathway that mediates strong resistance to viruses with a route-specific role. These results contribute to a better understanding of viral oral infection resistance in insects, which is particularly relevant in the context of transmission of arboviruses by insect vectors. Pathogenic microbes can enter their hosts through different routes. This can have a strong impact on which host defensive mechanisms are elicited and in disease outcome. We used the model organism Drosophila melanogaster to understand how resistance to viruses differs between infection by direct virus entry into the body cavity and infection through feeding on food with the virus. We show that the Toll pathway is required to resist oral infection with different RNA viruses. On the other hand this pathway does not influence the outcome of viral infection performed by injection. Together our results show that the Toll pathway has a route-specific general antiviral effect. Our work expands the role of this classical innate immunity pathway and contributes to a better understanding of viral oral infection resistance in insects. This is particularly relevant because insect vectors of emerging human viral diseases, like dengue, are infected through feeding on contaminated hosts.
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Affiliation(s)
| | - Huw Naylor
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | | | | | | | - Luis Teixeira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail: ,
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31
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Ballard SL, Miller DL, Ganetzky B. Retrograde neurotrophin signaling through Tollo regulates synaptic growth in Drosophila. ACTA ACUST UNITED AC 2014; 204:1157-72. [PMID: 24662564 PMCID: PMC3971753 DOI: 10.1083/jcb.201308115] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Toll-like receptor Tollo positively regulates growth of the Drosophila larval neuromuscular junction through the JNK pathway after activation by the neurotrophin Spätzle3. Toll-like receptors (TLRs) are best characterized for their roles in mediating dorsoventral patterning and the innate immune response. However, recent studies indicate that TLRs are also involved in regulating neuronal growth and development. Here, we demonstrate that the TLR Tollo positively regulates growth of the Drosophila melanogaster larval neuromuscular junction (NMJ). Tollo mutants exhibited NMJ undergrowth, whereas increased expression of Tollo led to NMJ overgrowth. Tollo expression in the motoneuron was both necessary and sufficient for regulating NMJ growth. Dominant genetic interactions together with altered levels of phosphorylated c-Jun N-terminal kinase (JNK) and puc-lacZ expression revealed that Tollo signals through the JNK pathway at the NMJ. Genetic interactions also revealed that the neurotrophin Spätzle3 (Spz3) is a likely Tollo ligand. Spz3 expression in muscle and proteolytic activation via the Easter protease was necessary and sufficient to promote NMJ growth. These results demonstrate the existence of a novel neurotrophin signaling pathway that is required for synaptic development in Drosophila.
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Affiliation(s)
- Shannon L Ballard
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53705
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