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Lewandowska-Wosik A, Chudzińska EM, Wojnicka-Półtorak A. Genotoxic effects of sub-lethal doses of nicotine and acetamiprid in neuroblasts of Drosophila melanogaster and Drosophila suzukii. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 280:116585. [PMID: 38875821 DOI: 10.1016/j.ecoenv.2024.116585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/05/2024] [Accepted: 06/09/2024] [Indexed: 06/16/2024]
Abstract
Neonicotinoids form a class of insecticides that are chemically related to nicotine and are widely used in crop protection. They have adverse effects on the neuronal nicotinic acetylcholine receptors (nAChRs). One of the neonicotinoids approved for control of the invasive pest Drosophila suzukii is acetamiprid. Despite concerns regarding its genotoxicity and data indicating the presence of small amounts of this substance in fruits intended for consumption, effects of its low doses on nerve cells are yet to be investigated. To determine whether the neurotoxic effects are species-specific and vary depending on the insecticide present in diet, multigenerational cultures of Drosophila melanogaster and D. suzukii were prepared, in this study, in media supplemented with different concentrations (below the LC50) of acetamiprid and nicotine. Acetamiprid, analogous to nicotine, caused damage to the DNA of neuroblasts in both species, at sublethal concentrations, along with a decrease in mobility, which remained at a similar level over subsequent generations. D. suzukii was found to be more sensitive to nicotine and acetamiprid, due to which the genotoxic effects were stronger even at lower doses of toxins. The results collectively indicated that even low concentrations of acetamiprid affect the stem cells of developing fly brain, and that long-term response to the tested insecticides is species-specific.
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Affiliation(s)
- Anetta Lewandowska-Wosik
- Department of Genetic, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University in Poznan, Poznan 61-614, Poland.
| | - Ewa Małgorzata Chudzińska
- Department of Genetic, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University in Poznan, Poznan 61-614, Poland
| | - Aleksandra Wojnicka-Półtorak
- Department of Genetic, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University in Poznan, Poznan 61-614, Poland
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2
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Mukherjee A, Andrés Jeske Y, Becam I, Taïeb A, Brooks P, Aouad J, Monguillon C, Conduit PT. γ-TuRCs and the augmin complex are required for the development of highly branched dendritic arbors in Drosophila. J Cell Sci 2024; 137:jcs261534. [PMID: 38606636 PMCID: PMC11128279 DOI: 10.1242/jcs.261534] [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: 08/04/2023] [Accepted: 04/05/2024] [Indexed: 04/13/2024] Open
Abstract
Microtubules are nucleated by γ-tubulin ring complexes (γ-TuRCs) and are essential for neuronal development. Nevertheless, γ-TuRC depletion has been reported to perturb only higher-order branching in elaborated Drosophila larval class IV dendritic arborization (da) neurons. This relatively mild phenotype has been attributed to defects in microtubule nucleation from Golgi outposts, yet most Golgi outposts lack associated γ-TuRCs. By analyzing dendritic arbor regrowth in pupae, we show that γ-TuRCs are also required for the growth and branching of primary and secondary dendrites, as well as for higher-order branching. Moreover, we identify the augmin complex (hereafter augmin), which recruits γ-TuRCs to the sides of pre-existing microtubules, as being required predominantly for higher-order branching. Augmin strongly promotes the anterograde growth of microtubules in terminal dendrites and thus terminal dendrite stability. Consistent with a specific role in higher-order branching, we find that augmin is expressed less strongly and is largely dispensable in larval class I da neurons, which exhibit few higher-order dendrites. Thus, γ-TuRCs are essential for various aspects of complex dendritic arbor development, and they appear to function in higher-order branching via the augmin pathway, which promotes the elaboration of dendritic arbors to help define neuronal morphology.
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Affiliation(s)
- Amrita Mukherjee
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- MRC Toxicology Unit, Gleeson Building, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Yaiza Andrés Jeske
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Isabelle Becam
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Anaelle Taïeb
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Paul Brooks
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Joanna Aouad
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | | | - Paul T. Conduit
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
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3
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Wasilewicz LJ, Gagnon ZE, Jung J, Mercier AJ. Investigating postsynaptic effects of a Drosophila neuropeptide on muscle contraction. J Neurophysiol 2024; 131:137-151. [PMID: 38150542 DOI: 10.1152/jn.00246.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 11/20/2023] [Accepted: 12/20/2023] [Indexed: 12/29/2023] Open
Abstract
The Drosophila neuropeptide, DPKQDFMRFamide, was previously shown to enhance excitatory junctional potentials (EJPs) and muscle contraction by both presynaptic and postsynaptic actions. Since the peptide acts on both sides of the synaptic cleft, it has been difficult to examine postsynaptic modulatory mechanisms, particularly when contractions are elicited by nerve stimulation. Here, postsynaptic actions are examined in 3rd instar larvae by applying peptide and the excitatory neurotransmitter, l-glutamate, in the bathing solution to elicit contractions after silencing motor output by removing the central nervous system (CNS). DPKQDFMRFamide enhanced glutamate-evoked contractions at low concentrations (EC50 1.3 nM), consistent with its role as a neurohormone, and the combined effect of both substances was supra-additive. Glutamate-evoked contractions were also enhanced when transmitter release was blocked in temperature-sensitive (Shibire) mutants, confirming the peptide's postsynaptic action. The peptide increased membrane depolarization in muscle when co-applied with glutamate, and its effects were blocked by nifedipine, an L-type channel blocker, indicating effects at the plasma membrane involving calcium influx. DPKQDFMRFamide also enhanced contractions induced by caffeine in the absence of extracellular calcium, suggesting increased calcium release from the sarcoplasmic reticulum (SR) or effects downstream of calcium release from the SR. The peptide's effects do not appear to involve calcium/calmodulin-dependent protein kinase II (CaMKII), previously shown to mediate presynaptic effects. The approach used here might be useful for examining postsynaptic effects of neurohormones and cotransmitters in other systems.NEW & NOTEWORTHY Distinguishing presynaptic and postsynaptic effects of neurohormones is a long-standing challenge in many model organisms. Here, postsynaptic actions of DPKQDFMRFamide are demonstrated by assessing its ability to potentiate contractions elicited by direct application of the neurotransmitter, glutamate, when axons are silent and when transmitter release is blocked. The peptide acts at multiple sites to increase contraction, increasing glutamate-induced depolarization at the cell membrane, acting on L-type channels, and acting downstream of calcium release from the sarcoplasmic reticulum.
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Affiliation(s)
- Lucas J Wasilewicz
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Zoe E Gagnon
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - JaeHwan Jung
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - A Joffre Mercier
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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4
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Bazzi W, Monticelli S, Delaporte C, Riet C, Giangrande A, Cattenoz PB. Gcm counteracts Toll-induced inflammation and impacts hemocyte number through cholinergic signaling. Front Immunol 2023; 14:1293766. [PMID: 38035083 PMCID: PMC10684909 DOI: 10.3389/fimmu.2023.1293766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 10/26/2023] [Indexed: 12/02/2023] Open
Abstract
Hemocytes, the myeloid-like immune cells of Drosophila, fulfill a variety of functions that are not completely understood, ranging from phagocytosis to transduction of inflammatory signals. We here show that downregulating the hemocyte-specific Glial cell deficient/Glial cell missing (Glide/Gcm) transcription factor enhances the inflammatory response to the constitutive activation of the Toll pathway. This correlates with lower levels of glutathione S-transferase, suggesting an implication of Glide/Gcm in reactive oxygen species (ROS) signaling and calling for a widespread anti-inflammatory potential of Glide/Gcm. In addition, our data reveal the expression of acetylcholine receptors in hemocytes and that Toll activation affects their expressions, disclosing a novel aspect of the inflammatory response mediated by neurotransmitters. Finally, we provide evidence for acetylcholine receptor nicotinic acetylcholine receptor alpha 6 (nAchRalpha6) regulating hemocyte proliferation in a cell autonomous fashion and for non-cell autonomous cholinergic signaling regulating the number of hemocytes. Altogether, this study provides new insights on the molecular pathways involved in the inflammatory response.
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Affiliation(s)
- Wael Bazzi
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Sara Monticelli
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Claude Delaporte
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Céline Riet
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Angela Giangrande
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
| | - Pierre B. Cattenoz
- Université de Strasbourg, IGBMC UMR 7104- UMR-S 1258, Illkirch, France
- CNRS, UMR 7104, Illkirch, France
- Inserm, UMR-S 1258, Illkirch, France
- IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
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Dallmann CJ, Dickerson BH, Simpson JH, Wyart C, Jayaram K. Mechanosensory Control of Locomotion in Animals and Robots: Moving Forward. Integr Comp Biol 2023; 63:450-463. [PMID: 37279901 PMCID: PMC10445419 DOI: 10.1093/icb/icad057] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/10/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023] Open
Abstract
While animals swim, crawl, walk, and fly with apparent ease, building robots capable of robust locomotion remains a significant challenge. In this review, we draw attention to mechanosensation-the sensing of mechanical forces generated within and outside the body-as a key sense that enables robust locomotion in animals. We discuss differences between mechanosensation in animals and current robots with respect to (1) the encoding properties and distribution of mechanosensors and (2) the integration and regulation of mechanosensory feedback. We argue that robotics would benefit greatly from a detailed understanding of these aspects in animals. To that end, we highlight promising experimental and engineering approaches to study mechanosensation, emphasizing the mutual benefits for biologists and engineers that emerge from moving forward together.
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Affiliation(s)
- Chris J Dallmann
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Bradley H Dickerson
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - Julie H Simpson
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Claire Wyart
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, Paris 75005, France
| | - Kaushik Jayaram
- Paul M Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
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6
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Kohsaka H. Linking neural circuits to the mechanics of animal behavior in Drosophila larval locomotion. Front Neural Circuits 2023; 17:1175899. [PMID: 37711343 PMCID: PMC10499525 DOI: 10.3389/fncir.2023.1175899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/13/2023] [Indexed: 09/16/2023] Open
Abstract
The motions that make up animal behavior arise from the interplay between neural circuits and the mechanical parts of the body. Therefore, in order to comprehend the operational mechanisms governing behavior, it is essential to examine not only the underlying neural network but also the mechanical characteristics of the animal's body. The locomotor system of fly larvae serves as an ideal model for pursuing this integrative approach. By virtue of diverse investigation methods encompassing connectomics analysis and quantification of locomotion kinematics, research on larval locomotion has shed light on the underlying mechanisms of animal behavior. These studies have elucidated the roles of interneurons in coordinating muscle activities within and between segments, as well as the neural circuits responsible for exploration. This review aims to provide an overview of recent research on the neuromechanics of animal locomotion in fly larvae. We also briefly review interspecific diversity in fly larval locomotion and explore the latest advancements in soft robots inspired by larval locomotion. The integrative analysis of animal behavior using fly larvae could establish a practical framework for scrutinizing the behavior of other animal species.
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Affiliation(s)
- Hiroshi Kohsaka
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo, Japan
- Department of Complexity Science and Engineering, Graduate School of Frontier Science, The University of Tokyo, Chiba, Japan
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7
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Greaney MR, Wreden CC, Heckscher ES. Distinctive features of the central synaptic organization of Drosophila larval proprioceptors. Front Neural Circuits 2023; 17:1223334. [PMID: 37564629 PMCID: PMC10410283 DOI: 10.3389/fncir.2023.1223334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/07/2023] [Indexed: 08/12/2023] Open
Abstract
Proprioceptive feedback is critically needed for locomotor control, but how this information is incorporated into central proprioceptive processing circuits remains poorly understood. Circuit organization emerges from the spatial distribution of synaptic connections between neurons. This distribution is difficult to discern in model systems where only a few cells can be probed simultaneously. Therefore, we turned to a relatively simple and accessible nervous system to ask: how are proprioceptors' input and output synapses organized in space, and what principles underlie this organization? Using the Drosophila larval connectome, we generated a map of the input and output synapses of 34 proprioceptors in several adjacent body segments (5-6 left-right pairs per segment). We characterized the spatial organization of these synapses, and compared this organization to that of other somatosensory neurons' synapses. We found three distinguishing features of larval proprioceptor synapses: (1) Generally, individual proprioceptor types display segmental somatotopy. (2) Proprioceptor output synapses both converge and diverge in space; they are organized into six spatial domains, each containing a unique set of one or more proprioceptors. Proprioceptors form output synapses along the proximal axonal entry pathway into the neuropil. (3) Proprioceptors receive few inhibitory input synapses. Further, we find that these three features do not apply to other larval somatosensory neurons. Thus, we have generated the most comprehensive map to date of how proprioceptor synapses are centrally organized. This map documents previously undescribed features of proprioceptors, raises questions about underlying developmental mechanisms, and has implications for downstream proprioceptive processing circuits.
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Affiliation(s)
- Marie R. Greaney
- Committee on Neurobiology, The University of Chicago, Chicago, IL, United States
| | - Chris C. Wreden
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, United States
| | - Ellie S. Heckscher
- Committee on Neurobiology, The University of Chicago, Chicago, IL, United States
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, United States
- Institute for Neuroscience, The University of Chicago, Chicago, IL, United States
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8
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Boivin JC, Zhu J, Ohyama T. Nociception in fruit fly larvae. FRONTIERS IN PAIN RESEARCH 2023; 4:1076017. [PMID: 37006412 PMCID: PMC10063880 DOI: 10.3389/fpain.2023.1076017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/28/2023] [Indexed: 03/19/2023] Open
Abstract
Nociception, the process of encoding and processing noxious or painful stimuli, allows animals to detect and avoid or escape from potentially life-threatening stimuli. Here, we provide a brief overview of recent technical developments and studies that have advanced our understanding of the Drosophila larval nociceptive circuit and demonstrated its potential as a model system to elucidate the mechanistic basis of nociception. The nervous system of a Drosophila larva contains roughly 15,000 neurons, which allows for reconstructing the connectivity among them directly by transmission electron microscopy. In addition, the availability of genetic tools for manipulating the activity of individual neurons and recent advances in computational and high-throughput behavior analysis methods have facilitated the identification of a neural circuit underlying a characteristic nocifensive behavior. We also discuss how neuromodulators may play a key role in modulating the nociceptive circuit and behavioral output. A detailed understanding of the structure and function of Drosophila larval nociceptive neural circuit could provide insights into the organization and operation of pain circuits in mammals and generate new knowledge to advance the development of treatment options for pain in humans.
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Affiliation(s)
- Jean-Christophe Boivin
- Department of Biology, McGill University, Montreal, QC, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Jiayi Zhu
- Department of Biology, McGill University, Montreal, QC, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Tomoko Ohyama
- Department of Biology, McGill University, Montreal, QC, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
- Correspondence: Tomoko Ohyama
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9
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Nemtsova Y, Steinert BL, Wharton KA. Compartment specific mitochondrial dysfunction in Drosophila knock-in model of ALS reversed by altered gene expression of OXPHOS subunits and pro-fission factor Drp1. Mol Cell Neurosci 2023; 125:103834. [PMID: 36868541 DOI: 10.1016/j.mcn.2023.103834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 02/20/2023] [Accepted: 02/23/2023] [Indexed: 03/05/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a fatal multisystem neurodegenerative disease, characterized by a loss in motor function. ALS is genetically diverse, with mutations in genes ranging from those regulating RNA metabolism, like TAR DNA-binding protein (TDP-43) and Fused in sarcoma (FUS), to those that act to maintain cellular redox homeostasis, like superoxide dismutase 1 (SOD1). Although varied in genetic origin, pathogenic and clinical commonalities are clearly evident between cases of ALS. Defects in mitochondria is one such common pathology, thought to occur prior to, rather than as a consequence of symptom onset, making these organelles a promising therapeutic target for ALS, as well as other neurodegenerative diseases. Depending on the homeostatic needs of neurons throughout life, mitochondria are normally shuttled to different subcellular compartments to regulate metabolite and energy production, lipid metabolism, and buffer calcium. While originally considered a motor neuron disease due to the dramatic loss in motor function accompanied by motor neuron cell death in ALS patients, many studies have now implicated non-motor neurons and glial cells alike. Defects in non-motor neuron cell types often preceed motor neuron death suggesting their dysfunction may initiate and/or facilitate the decline in motor neuron health. Here, we investigate mitochondria in a Drosophila Sod1 knock-in model of ALS. In depth, in vivo, examination reveals mitochondrial dysfunction evident prior to onset of motor neuron degeneration. Genetically encoded redox biosensors identify a general disruption in the electron transport chain (ETC). Compartment specific abnormalities in mitochondrial morphology is observed in diseased sensory neurons, accompanied by no apparent defects in the axonal transport machinery, but instead an increase in mitophagy in synaptic regions. The decrease in networked mitochondria at the synapse is reversed upon downregulation of the pro-fission factor Drp1. Furthermore, altered expression of specific OXPHOS subunits reverses ALS-associated defects in mitochondrial morphology and function.
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Affiliation(s)
- Y Nemtsova
- Molecular Biology, Cell Biology, and Biochemistry Department, Brown University, Providence, RI 02912, United States.
| | - B L Steinert
- Molecular Biology, Cell Biology, and Biochemistry Department, Brown University, Providence, RI 02912, United States.
| | - K A Wharton
- Molecular Biology, Cell Biology, and Biochemistry Department, Brown University, Providence, RI 02912, United States; Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, United States.
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10
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Zeng X, Komanome Y, Kawasaki T, Inada K, Jonaitis J, Pulver SR, Kazama H, Nose A. An electrically coupled pioneer circuit enables motor development via proprioceptive feedback in Drosophila embryos. Curr Biol 2021; 31:5327-5340.e5. [PMID: 34666002 DOI: 10.1016/j.cub.2021.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 09/03/2021] [Accepted: 10/04/2021] [Indexed: 02/02/2023]
Abstract
Precocious movements are widely seen in embryos of various animal species. Whether such movements via proprioceptive feedback play instructive roles in motor development or are a mere reflection of activities in immature motor circuits is a long-standing question. Here we image the emerging motor activities in Drosophila embryos that lack proprioceptive feedback and show that proprioceptive experience is essential for the development of locomotor central pattern generators (CPGs). Downstream of proprioceptive inputs, we identify a pioneer premotor circuit composed of two pairs of segmental interneurons, whose gap-junctional transmission requires proprioceptive experience and plays a crucial role in CPG formation. The circuit autonomously generates rhythmic plateau potentials via IP3-mediated Ca2+ release from internal stores, which contribute to muscle contractions and hence produce proprioceptive feedback. Our findings demonstrate the importance of self-generated movements in instructing motor development and identify the cells, circuit, and physiology at the core of this proprioceptive feedback.
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Affiliation(s)
- Xiangsunze Zeng
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Yuko Komanome
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Tappei Kawasaki
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Kengo Inada
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Julius Jonaitis
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews KY16 9JP, UK
| | - Stefan R Pulver
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews KY16 9JP, UK
| | - Hokto Kazama
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
| | - Akinao Nose
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan; Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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11
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Ormerod KG, Scibelli AE, Littleton JT. Regulation of excitation-contraction coupling at the Drosophila neuromuscular junction. J Physiol 2021; 600:349-372. [PMID: 34788476 DOI: 10.1113/jp282092] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/28/2021] [Indexed: 01/05/2023] Open
Abstract
The Drosophila neuromuscular system is widely used to characterize synaptic development and function. However, little is known about how specific synaptic alterations effect neuromuscular transduction and muscle contractility, which ultimately dictate behavioural output. Here we develop and use a force transducer system to characterize excitation-contraction coupling at Drosophila larval neuromuscular junctions (NMJs), examining how specific neuronal and muscle manipulations disrupt muscle contractility. Muscle contraction force increased with motoneuron stimulation frequency and duration, showing considerable plasticity between 5 and 40 Hz and saturating above 50 Hz. Endogenous recordings of fictive contractions revealed average motoneuron burst frequencies of 20-30 Hz, consistent with the system operating within this plastic range of contractility. Temperature was also a key factor in muscle contractility, as force was enhanced at lower temperatures and dramatically reduced with increasing temperatures. Pharmacological and genetic manipulations of critical components of Ca2+ regulation in both pre- and postsynaptic compartments affected the strength and time course of muscle contractions. A screen for modulators of muscle contractility led to identification and characterization of the molecular and cellular pathway by which the FMRFa peptide, TPAEDFMRFa, increases muscle performance. These findings indicate Drosophila NMJs provide a robust system to correlate synaptic dysfunction, regulation and modulation to alterations in excitation-contraction coupling. KEY POINTS: Larval muscle contraction force increases with stimulation frequency and duration, revealing substantial plasticity between 5 and 40 Hz. Fictive contraction recordings demonstrate endogenous motoneuron burst frequencies consistent with the neuromuscular system operating within the range of greatest plasticity. Genetic and pharmacological manipulations of critical components of pre- and postsynaptic Ca2+ regulation significantly affect the strength and time course of muscle contractions. A screen for modulators of the excitation-contraction machinery identified a FMRFa peptide, TPAEDFMRFa and its associated signalling pathway, that dramatically increases muscle performance. Drosophila serves as an excellent model for dissecting components of the excitation-contraction coupling machinery.
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Affiliation(s)
- Kiel G Ormerod
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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12
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Kilo L, Stürner T, Tavosanis G, Ziegler AB. Drosophila Dendritic Arborisation Neurons: Fantastic Actin Dynamics and Where to Find Them. Cells 2021; 10:2777. [PMID: 34685757 PMCID: PMC8534399 DOI: 10.3390/cells10102777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 01/27/2023] Open
Abstract
Neuronal dendrites receive, integrate, and process numerous inputs and therefore serve as the neuron's "antennae". Dendrites display extreme morphological diversity across different neuronal classes to match the neuron's specific functional requirements. Understanding how this structural diversity is specified is therefore important for shedding light on information processing in the healthy and diseased nervous system. Popular models for in vivo studies of dendrite differentiation are the four classes of dendritic arborization (c1da-c4da) neurons of Drosophila larvae with their class-specific dendritic morphologies. Using da neurons, a combination of live-cell imaging and computational approaches have delivered information on the distinct phases and the time course of dendrite development from embryonic stages to the fully developed dendritic tree. With these data, we can start approaching the basic logic behind differential dendrite development. A major role in the definition of neuron-type specific morphologies is played by dynamic actin-rich processes and the regulation of their properties. This review presents the differences in the growth programs leading to morphologically different dendritic trees, with a focus on the key role of actin modulatory proteins. In addition, we summarize requirements and technological progress towards the visualization and manipulation of such actin regulators in vivo.
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Affiliation(s)
- Lukas Kilo
- Dendrite Differentiation, German Center for Neurodegenerative Diseases, 53115 Bonn, Germany; (L.K.); (G.T.)
| | - Tomke Stürner
- Department of Zoology, University of Cambridge, Cambridge CB2 1TN, UK;
| | - Gaia Tavosanis
- Dendrite Differentiation, German Center for Neurodegenerative Diseases, 53115 Bonn, Germany; (L.K.); (G.T.)
- LIMES-Institute, University of Bonn, 53115 Bonn, Germany
| | - Anna B. Ziegler
- Institute of Neuro- and Behavioral Biology, University of Münster, 48149 Münster, Germany
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13
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Galbraith A, Leone S, Stuart K, Emery J, Renkemeyer MK, Pritchett N, Galbraith L, Stuckmeyer H, Berke B. Reducing the expression of the Numb adaptor protein in neurons increases the searching behavior of Drosophila larvae. MICROPUBLICATION BIOLOGY 2021; 2021:10.17912/micropub.biology.000426. [PMID: 34327314 PMCID: PMC8314082 DOI: 10.17912/micropub.biology.000426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 11/23/2022]
Abstract
Drosophila larval crawling is easily-observable and relatively stereotyped. Crawling consists of linear locomotion interrupted by periods when the larvae pause, swing their heads, and change direction (a 'search'). Here we identify Numb, a peripheral membrane adaptor protein, as an important regulator of searching behavior. When Numb RNAi transgenes were expressed in all neurons, searching frequency increased while linear movement appeared normal. Numb's role in suppressing searching behavior was verified by rescuing this phenotype with a Numb homologue from mice. Such behavioral specificity suggests that further analysis of searching might help identify additional, evolutionarily-conserved interactors of the Numb protein.
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Affiliation(s)
- Andrew Galbraith
- Department of Biology, Truman State University, Kirksville, MO USA
| | - Samuel Leone
- Department of Biology, Truman State University, Kirksville, MO USA
| | - Katherine Stuart
- Department of Biology, Truman State University, Kirksville, MO USA
| | - Josie Emery
- Department of Biology, Truman State University, Kirksville, MO USA
| | | | | | - Lauren Galbraith
- Department of Biology, Truman State University, Kirksville, MO USA
| | - Haley Stuckmeyer
- Department of Biology, Truman State University, Kirksville, MO USA
| | - Brett Berke
- Department of Biology, Truman State University, Kirksville, MO USA,
Correspondence to: Brett Berke ()
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14
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Liao M, Liang X, Howard J. The narrowing of dendrite branches across nodes follows a well-defined scaling law. Proc Natl Acad Sci U S A 2021; 118:e2022395118. [PMID: 34215693 PMCID: PMC8271565 DOI: 10.1073/pnas.2022395118] [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] [Indexed: 11/18/2022] Open
Abstract
The systematic variation of diameters in branched networks has tantalized biologists since the discovery of da Vinci's rule for trees. Da Vinci's rule can be formulated as a power law with exponent two: The square of the mother branch's diameter is equal to the sum of the squares of those of the daughters. Power laws, with different exponents, have been proposed for branching in circulatory systems (Murray's law with exponent 3) and in neurons (Rall's law with exponent 3/2). The laws have been derived theoretically, based on optimality arguments, but, for the most part, have not been tested rigorously. Using superresolution methods to measure the diameters of dendrites in highly branched Drosophila class IV sensory neurons, we have found that these types of power laws do not hold. In their place, we have discovered a different diameter-scaling law: The cross-sectional area is proportional to the number of dendrite tips supported by the branch plus a constant, corresponding to a minimum diameter of the terminal dendrites. The area proportionality accords with a requirement for microtubules to transport materials and nutrients for dendrite tip growth. The minimum diameter may be set by the force, on the order of a few piconewtons, required to bend membrane into the highly curved surfaces of terminal dendrites. Because the observed scaling differs from Rall's law, we propose that cell biological constraints, such as intracellular transport and protrusive forces generated by the cytoskeleton, are important in determining the branched morphology of these cells.
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Affiliation(s)
- Maijia Liao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520;
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15
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Yin C, Peterman E, Rasmussen JP, Parrish JZ. Transparent Touch: Insights From Model Systems on Epidermal Control of Somatosensory Innervation. Front Cell Neurosci 2021; 15:680345. [PMID: 34135734 PMCID: PMC8200473 DOI: 10.3389/fncel.2021.680345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 04/28/2021] [Indexed: 12/28/2022] Open
Abstract
Somatosensory neurons (SSNs) densely innervate our largest organ, the skin, and shape our experience of the world, mediating responses to sensory stimuli including touch, pressure, and temperature. Historically, epidermal contributions to somatosensation, including roles in shaping innervation patterns and responses to sensory stimuli, have been understudied. However, recent work demonstrates that epidermal signals dictate patterns of SSN skin innervation through a variety of mechanisms including targeting afferents to the epidermis, providing instructive cues for branching morphogenesis, growth control and structural stability of neurites, and facilitating neurite-neurite interactions. Here, we focus onstudies conducted in worms (Caenorhabditis elegans), fruit flies (Drosophila melanogaster), and zebrafish (Danio rerio): prominent model systems in which anatomical and genetic analyses have defined fundamental principles by which epidermal cells govern SSN development.
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Affiliation(s)
| | | | | | - Jay Z. Parrish
- Department of Biology, University of Washington, Seattle, WA, United States
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16
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Mase A, Augsburger J, Brückner K. Macrophages and Their Organ Locations Shape Each Other in Development and Homeostasis - A Drosophila Perspective. Front Cell Dev Biol 2021; 9:630272. [PMID: 33777939 PMCID: PMC7991785 DOI: 10.3389/fcell.2021.630272] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/25/2021] [Indexed: 12/15/2022] Open
Abstract
Across the animal kingdom, macrophages are known for their functions in innate immunity, but they also play key roles in development and homeostasis. Recent insights from single cell profiling and other approaches in the invertebrate model organism Drosophila melanogaster reveal substantial diversity among Drosophila macrophages (plasmatocytes). Together with vertebrate studies that show genuine expression signatures of macrophages based on their organ microenvironments, it is expected that Drosophila macrophage functional diversity is shaped by their anatomical locations and systemic conditions. In vivo evidence for diverse macrophage functions has already been well established by Drosophila genetics: Drosophila macrophages play key roles in various aspects of development and organogenesis, including embryogenesis and development of the nervous, digestive, and reproductive systems. Macrophages further maintain homeostasis in various organ systems and promote regeneration following organ damage and injury. The interdependence and interplay of tissues and their local macrophage populations in Drosophila have implications for understanding principles of organ development and homeostasis in a wide range of species.
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Affiliation(s)
- Anjeli Mase
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, United States
| | - Jordan Augsburger
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, United States
| | - Katja Brückner
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, United States
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
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17
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Belalcazar HM, Hendricks EL, Zamurrad S, Liebl FLW, Secombe J. The histone demethylase KDM5 is required for synaptic structure and function at the Drosophila neuromuscular junction. Cell Rep 2021; 34:108753. [PMID: 33596422 PMCID: PMC7945993 DOI: 10.1016/j.celrep.2021.108753] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/14/2020] [Accepted: 01/25/2021] [Indexed: 02/08/2023] Open
Abstract
Mutations in the genes encoding the lysine demethylase 5 (KDM5) family of histone demethylases are observed in individuals with intellectual disability (ID). Despite clear evidence linking KDM5 function to neurodevelopmental pathways, how this family of proteins impacts transcriptional programs to mediate synaptic structure and activity remains unclear. Using the Drosophila larval neuromuscular junction (NMJ), we show that KDM5 is required presynaptically for neuroanatomical development and synaptic function. The Jumonji C (JmjC) domain-encoded histone demethylase activity of KDM5, which is expected to be diminished by many ID-associated alleles, is required for appropriate synaptic morphology and neurotransmission. The activity of the C5HC2 zinc finger is also required, as an ID-associated mutation in this motif reduces NMJ bouton number, increases bouton size, and alters microtubule dynamics. KDM5 therefore uses demethylase-dependent and independent mechanisms to regulate NMJ structure and activity, highlighting the complex nature by which this chromatin modifier carries out its neuronal gene-regulatory programs.
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Affiliation(s)
- Helen M Belalcazar
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Emily L Hendricks
- Department of Biological Sciences, Southern Illinois University Edwardsville, 44 Circle Drive, Edwardsville, IL 62026, USA
| | - Sumaira Zamurrad
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Faith L W Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, 44 Circle Drive, Edwardsville, IL 62026, USA
| | - Julie Secombe
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461, USA.
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18
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Gowda SBM, Salim S, Mohammad F. Anatomy and Neural Pathways Modulating Distinct Locomotor Behaviors in Drosophila Larva. BIOLOGY 2021; 10:90. [PMID: 33504061 PMCID: PMC7910854 DOI: 10.3390/biology10020090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/07/2020] [Accepted: 12/30/2020] [Indexed: 11/17/2022]
Abstract
The control of movements is a fundamental feature shared by all animals. At the most basic level, simple movements are generated by coordinated neural activity and muscle contraction patterns that are controlled by the central nervous system. How behavioral responses to various sensory inputs are processed and integrated by the downstream neural network to produce flexible and adaptive behaviors remains an intense area of investigation in many laboratories. Due to recent advances in experimental techniques, many fundamental neural pathways underlying animal movements have now been elucidated. For example, while the role of motor neurons in locomotion has been studied in great detail, the roles of interneurons in animal movements in both basic and noxious environments have only recently been realized. However, the genetic and transmitter identities of many of these interneurons remains unclear. In this review, we provide an overview of the underlying circuitry and neural pathways required by Drosophila larvae to produce successful movements. By improving our understanding of locomotor circuitry in model systems such as Drosophila, we will have a better understanding of how neural circuits in organisms with different bodies and brains lead to distinct locomotion types at the organism level. The understanding of genetic and physiological components of these movements types also provides directions to understand movements in higher organisms.
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Affiliation(s)
| | | | - Farhan Mohammad
- Division of Biological and Biomedical Sciences (BBS), College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Doha 34110, Qatar; (S.B.M.G.); (S.S.)
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19
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Bag J, Mukherjee S, Ghosh SK, Das A, Mukherjee A, Sahoo JK, Tung KS, Sahoo H, Mishra M. Fe 3O 4 coated guargum nanoparticles as non-genotoxic materials for biological application. Int J Biol Macromol 2020; 165:333-345. [PMID: 32980413 DOI: 10.1016/j.ijbiomac.2020.09.144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/04/2020] [Accepted: 09/19/2020] [Indexed: 02/06/2023]
Abstract
The current study aims to check various behavioural, developmental, cytotoxic, and genotoxic effects of Fe3O4-GG nanocomposite (GGNCs) on Drosophila melanogaster. Fe3O4 nanoparticles were prepared by the chemical co-precipitation method and cross-linked with guargum nanoparticles to prepare the nanocomposites. The nanocomposites were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and FTIR techniques. To investigate the biomolecular interaction, GGNCs was further tagged with Fluorescein isothiocyanate. Various concentrations of nanocomposites were mixed with the food and flies were allowed to complete the life cycle. The life cycle of the flies was studied as a function of various concentrations of GGNCs. The 1st instar larvae after hatching from the egg start eating the food mixed with GGNCs. The 3rd instar larvae were investigated for various behavioural and morphological abnormalities within the gut. The 3rd instar larva has defective crawling speed, crawling path, and more number of micronuclei within the gut. Similarly, in adult flies thermal sensitivity, climbing behaviour was found to be altered. In adult flies, a significant reduction in body weight was found which is further correlated with variation of protein, carbohydrate, triglyceride, and antioxidant enzymes. Altogether, the current study suggests GGNCs as a non-genotoxic nanoparticle for various biological applications.
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Affiliation(s)
- Janmejaya Bag
- Neural Developmental Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha 769008, India
| | - Sumit Mukherjee
- Neural Developmental Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha 769008, India
| | - Sumanta Kumar Ghosh
- Division of Pharmaceutical and Fine Chemical Technology, Department of Chemical Technology, University of Calcutta, West Bengal 700009, India
| | - Aatrayee Das
- Division of Pharmaceutical and Fine Chemical Technology, Department of Chemical Technology, University of Calcutta, West Bengal 700009, India
| | - Arup Mukherjee
- Division of Pharmaceutical and Fine Chemical Technology, Department of Chemical Technology, University of Calcutta, West Bengal 700009, India; Department of Biotechnology, MaulanaAbulKalam Azad University of Technology, West Bengal 741249, India.
| | - Jitendra Kumar Sahoo
- Department of Chemistry, NIT Rourkela, Rourkela, Odisha 769008, India; Department of Basic Science and Humanities, GIET University, Gunupur, Odisha 765022, India
| | - Kshyama Subhadarsini Tung
- Neural Developmental Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha 769008, India
| | - Harekrushna Sahoo
- Department of Chemistry, NIT Rourkela, Rourkela, Odisha 769008, India; Centre for Nanomaterials, NIT Rourkela, Rourkela, Odisha 769008, India
| | - Monalisa Mishra
- Neural Developmental Biology Lab, Department of Life Science, NIT Rourkela, Rourkela, Odisha 769008, India; Centre for Nanomaterials, NIT Rourkela, Rourkela, Odisha 769008, India.
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20
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Murawski C, Pulver SR, Gather MC. Segment-specific optogenetic stimulation in Drosophila melanogaster with linear arrays of organic light-emitting diodes. Nat Commun 2020; 11:6248. [PMID: 33288763 PMCID: PMC7721879 DOI: 10.1038/s41467-020-20013-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 11/06/2020] [Indexed: 11/08/2022] Open
Abstract
Optogenetics allows light-driven, non-contact control of neural systems, but light delivery remains challenging, in particular when fine spatial control of light is required to achieve local specificity. Here, we employ organic light-emitting diodes (OLEDs) that are micropatterned into linear arrays to obtain precise optogenetic control in Drosophila melanogaster larvae expressing the light-gated activator CsChrimson and the inhibitor GtACR2 within their peripheral sensory system. Our method allows confinement of light stimuli to within individual abdominal segments, which facilitates the study of larval behaviour in response to local sensory input. We show controlled triggering of specific crawling modes and find that targeted neurostimulation in abdominal segments switches the direction of crawling. More broadly, our work demonstrates how OLEDs can provide tailored patterns of light for photo-stimulation of neuronal networks, with future implications ranging from mapping neuronal connectivity in cultures to targeted photo-stimulation with pixelated OLED implants in vivo.
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Affiliation(s)
- Caroline Murawski
- Organic Semiconductor Centre and Centre of Biophotonics, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Kurt-Schwabe-Institut für Mess- und Sensortechnik Meinsberg e.V., Kurt-Schwabe-Str. 4, 04736, Waldheim, Germany
| | - Stefan R Pulver
- School of Psychology and Neuroscience and Centre of Biophotonics, University of St Andrews, St Mary's Quad, South Street, St Andrews, KY16 9JP, UK
| | - Malte C Gather
- Organic Semiconductor Centre and Centre of Biophotonics, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK.
- Centre for Nanobiophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Köln, Germany.
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21
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Eschbach C, Zlatic M. Useful road maps: studying Drosophila larva's central nervous system with the help of connectomics. Curr Opin Neurobiol 2020; 65:129-137. [PMID: 33242722 PMCID: PMC7773133 DOI: 10.1016/j.conb.2020.09.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/21/2020] [Accepted: 09/24/2020] [Indexed: 12/16/2022]
Abstract
The larva of Drosophila melanogaster is emerging as a powerful model system for comprehensive brain-wide understanding of the circuit implementation of neural computations. With an unprecedented amount of tools in hand, including synaptic-resolution connectomics, whole-brain imaging, and genetic tools for selective targeting of single neuron types, it is possible to dissect which circuits and computations are at work behind behaviors that have an interesting level of complexity. Here we present some of the recent advances regarding multisensory integration, learning, and action selection in Drosophila larva.
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Affiliation(s)
- Claire Eschbach
- Department of Zoology, University of Cambridge, United Kingdom.
| | - Marta Zlatic
- Department of Zoology, University of Cambridge, United Kingdom; MRC Laboratory of Molecular Biology, United Kingdom.
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22
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Ferreira Castro A, Baltruschat L, Stürner T, Bahrami A, Jedlicka P, Tavosanis G, Cuntz H. Achieving functional neuronal dendrite structure through sequential stochastic growth and retraction. eLife 2020; 9:e60920. [PMID: 33241995 PMCID: PMC7837678 DOI: 10.7554/elife.60920] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 11/15/2020] [Indexed: 02/06/2023] Open
Abstract
Class I ventral posterior dendritic arborisation (c1vpda) proprioceptive sensory neurons respond to contractions in the Drosophila larval body wall during crawling. Their dendritic branches run along the direction of contraction, possibly a functional requirement to maximise membrane curvature during crawling contractions. Although the molecular machinery of dendritic patterning in c1vpda has been extensively studied, the process leading to the precise elaboration of their comb-like shapes remains elusive. Here, to link dendrite shape with its proprioceptive role, we performed long-term, non-invasive, in vivo time-lapse imaging of c1vpda embryonic and larval morphogenesis to reveal a sequence of differentiation stages. We combined computer models and dendritic branch dynamics tracking to propose that distinct sequential phases of stochastic growth and retraction achieve efficient dendritic trees both in terms of wire and function. Our study shows how dendrite growth balances structure-function requirements, shedding new light on general principles of self-organisation in functionally specialised dendrites.
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Affiliation(s)
- André Ferreira Castro
- Frankfurt Institute for Advanced StudiesFrankfurt am MainGermany
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck SocietyFrankfurt am MainGermany
- Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | | | - Tomke Stürner
- Center for Neurodegenerative Diseases (DZNE)BonnGermany
- Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | | | - Peter Jedlicka
- Frankfurt Institute for Advanced StudiesFrankfurt am MainGermany
- Faculty of Medicine, ICAR3R – Interdisciplinary Centre for 3Rs in Animal Research, Justus Liebig University GiessenGiessenGermany
- Neuroscience Center, Institute of Clinical Neuroanatomy, Goethe UniversityFrankfurt am MainGermany
| | - Gaia Tavosanis
- Center for Neurodegenerative Diseases (DZNE)BonnGermany
- LIMES Institute, University of BonnBonnGermany
| | - Hermann Cuntz
- Frankfurt Institute for Advanced StudiesFrankfurt am MainGermany
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck SocietyFrankfurt am MainGermany
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23
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Controlling the behaviour of Drosophila melanogaster via smartphone optogenetics. Sci Rep 2020; 10:17614. [PMID: 33077824 PMCID: PMC7572528 DOI: 10.1038/s41598-020-74448-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 09/24/2020] [Indexed: 01/05/2023] Open
Abstract
Invertebrates such as Drosophila melanogaster have proven to be a valuable model organism for studies of the nervous system. In order to control neuronal activity, optogenetics has evolved as a powerful technique enabling non-invasive stimulation using light. This requires light sources that can deliver patterns of light with high temporal and spatial precision. Currently employed light sources for stimulation of small invertebrates, however, are either limited in spatial resolution or require sophisticated and bulky equipment. In this work, we used smartphone displays for optogenetic control of Drosophila melanogaster. We developed an open-source smartphone app that allows time-dependent display of light patterns and used this to activate and inhibit different neuronal populations in both larvae and adult flies. Characteristic behavioural responses were observed depending on the displayed colour and brightness and in agreement with the activation spectra and light sensitivity of the used channelrhodopsins. By displaying patterns of light, we constrained larval movement and were able to guide larvae on the display. Our method serves as a low-cost high-resolution testbench for optogenetic experiments using small invertebrate species and is particularly appealing to application in neuroscience teaching labs.
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24
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Metallo C, Mukherjee R, Trimmer BA. Stepping pattern changes in the caterpillar Manduca sexta: the effects of orientation and substrate. J Exp Biol 2020; 223:jeb220319. [PMID: 32527957 DOI: 10.1242/jeb.220319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/28/2020] [Indexed: 02/04/2023]
Abstract
Most animals can successfully travel across cluttered, uneven environments and cope with enormous changes in surface friction, deformability and stability. However, the mechanisms used to achieve such remarkable adaptability and robustness are not fully understood. Even more limited is the understanding of how soft, deformable animals such as tobacco hornworm Manduca sexta (caterpillars) can control their movements as they navigate surfaces that have varying stiffness and are oriented at different angles. To fill this gap, we analyzed the stepping patterns of caterpillars crawling on two different types of substrate (stiff and soft) and in three different orientations (horizontal and upward/downward vertical). Our results show that caterpillars adopt different stepping patterns (i.e. different sequences of transition between the swing and stance phases of prolegs in different body segments) based on substrate stiffness and orientation. These changes in stepping pattern occur more frequently in the upward vertical orientation. The results of this study suggest that caterpillars can detect differences in the material properties of the substrate on which they crawl and adjust their behavior to match those properties.
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Affiliation(s)
- Cinzia Metallo
- Tufts University, Biology Department, 200 Boston Avenue, room 2613, Medford, MA 02155, USA
| | - Ritwika Mukherjee
- Tufts University, Biology Department, 200 Boston Avenue, room 2613, Medford, MA 02155, USA
| | - Barry A Trimmer
- Tufts University, Biology Department, 200 Boston Avenue, room 2613, Medford, MA 02155, USA
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25
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Hassan A, Sapir L, Nitsan I, Greenblatt Ben-El RT, Halachmi N, Salzberg A, Tzlil S. A Change in ECM Composition Affects Sensory Organ Mechanics and Function. Cell Rep 2020; 27:2272-2280.e4. [PMID: 31116974 DOI: 10.1016/j.celrep.2019.04.092] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 02/12/2019] [Accepted: 04/18/2019] [Indexed: 11/26/2022] Open
Abstract
Proprioception requires the transduction of muscle-generated deformations into sensory neuronal impulses. In proprioceptive organs, the mechanical coupling between the sensory neuron and the muscle is mediated by a connective structure composed of accessory cells and an extracellular matrix (ECM). Here, we use the fly chordotonal organ (ChO) to investigate how the mechanical properties of the connective element affect mechanosensing. We show that the loss of Pericardin, a major constituent of the ChO ECM, alters the mechanical properties of the ChO resulting in short-wavelength buckling of the accessory cells upon muscle contraction and low compressive strain within the organ. We explain these results using a simplified theoretical model of an elastic beam interacting with an elastic network under a compressive force. We further demonstrate that the transition from compression to bending interferes with the ability of the accessory cells to propagate muscle-generated deformations correctly to the neuron and hence with proper sensing.
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Affiliation(s)
- Abeer Hassan
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Liel Sapir
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ido Nitsan
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Rina T Greenblatt Ben-El
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 3109601, Israel
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 3109601, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa 3109601, Israel
| | - Shelly Tzlil
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
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26
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Hu C, Kanellopoulos AK, Richter M, Petersen M, Konietzny A, Tenedini FM, Hoyer N, Cheng L, Poon CLC, Harvey KF, Windhorst S, Parrish JZ, Mikhaylova M, Bagni C, Calderon de Anda F, Soba P. Conserved Tao Kinase Activity Regulates Dendritic Arborization, Cytoskeletal Dynamics, and Sensory Function in Drosophila. J Neurosci 2020; 40:1819-1833. [PMID: 31964717 PMCID: PMC7046460 DOI: 10.1523/jneurosci.1846-19.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 12/11/2022] Open
Abstract
Dendritic arborization is highly regulated and requires tight control of dendritic growth, branching, cytoskeletal dynamics, and ion channel expression to ensure proper function. Abnormal dendritic development can result in altered network connectivity, which has been linked to neurodevelopmental disorders, including autism spectrum disorders (ASDs). How neuronal growth control programs tune dendritic arborization to ensure function is still not fully understood. Using Drosophila dendritic arborization (da) neurons as a model, we identified the conserved Ste20-like kinase Tao as a negative regulator of dendritic arborization. We show that Tao kinase activity regulates cytoskeletal dynamics and sensory channel localization required for proper sensory function in both male and female flies. We further provide evidence for functional conservation of Tao kinase, showing that its ASD-linked human ortholog, Tao kinase 2 (Taok2), could replace Drosophila Tao and rescue dendritic branching, dynamic microtubule alterations, and behavioral defects. However, several ASD-linked Taok2 variants displayed impaired rescue activity, suggesting that Tao/Taok2 mutations can disrupt sensory neuron development and function. Consistently, we show that Tao kinase activity is required in developing and as well as adult stages for maintaining normal dendritic arborization and sensory function to regulate escape and social behavior. Our data suggest an important role for Tao kinase signaling in cytoskeletal organization to maintain proper dendritic arborization and sensory function, providing a strong link between developmental sensory aberrations and behavioral abnormalities relevant for Taok2-dependent ASDs.SIGNIFICANCE STATEMENT Autism spectrum disorders (ASDs) are linked to abnormal dendritic arbors. However, the mechanisms of how dendritic arbors develop to promote functional and proper behavior are unclear. We identified Drosophila Tao kinase, the ortholog of the ASD risk gene Taok2, as a regulator of dendritic arborization in sensory neurons. We show that Tao kinase regulates cytoskeletal dynamics, controls sensory ion channel localization, and is required to maintain somatosensory function in vivo Interestingly, ASD-linked human Taok2 mutations rendered it nonfunctional, whereas its WT form could restore neuronal morphology and function in Drosophila lacking endogenous Tao. Our findings provide evidence for a conserved role of Tao kinase in dendritic development and function of sensory neurons, suggesting that aberrant sensory function might be a common feature of ASDs.
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Affiliation(s)
- Chun Hu
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | | | - Melanie Richter
- Neuronal Development Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Meike Petersen
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Anja Konietzny
- Neuronal Protein Transport Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Federico M Tenedini
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nina Hoyer
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lin Cheng
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Carole L C Poon
- Peter MacCallum Cancer Centre, Melbourne, 3000 Victoria, Australia
| | - Kieran F Harvey
- Peter MacCallum Cancer Centre, Melbourne, 3000 Victoria, Australia
- Department of Anatomy and Developmental Biology, and Biomedicine Discovery Institute, Monash University, Clayton, 3800 Victoria, Australia
| | - Sabine Windhorst
- Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, 98195 Washington, and
| | - Marina Mikhaylova
- Neuronal Protein Transport Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Froylan Calderon de Anda
- Neuronal Development Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Peter Soba
- Neuronal Patterning and Connectivity Laboratory, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany,
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27
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Mustard JA, Jones L, Wright GA. GABA signaling affects motor function in the honey bee. JOURNAL OF INSECT PHYSIOLOGY 2020; 120:103989. [PMID: 31805284 DOI: 10.1016/j.jinsphys.2019.103989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/26/2019] [Accepted: 11/29/2019] [Indexed: 06/10/2023]
Abstract
GABA is the most common inhibitory neurotransmitter in both vertebrate and invertebrate nervous systems. In insects, inhibition plays important roles at the neuromuscular junction, in the regulation of central pattern generators, and in the modulation of information in higher brain processing centers. Additionally, increasing our understanding of the functions of GABA is important since GABAA receptors are the targets of several classes of pesticides. To investigate the role of GABA in motor function, honey bee foragers were injected with GABA or with agonists or antagonists specific for either GABAA or GABAB receptors. Compounds that activated either type of GABA receptor decreased activity levels. Bees injected with the GABAA receptor antagonist picrotoxin lost the ability to right themselves, whereas blockade of GABAB receptors led to increases in grooming. Injection with antagonists of either GABAA or GABAB receptors resulted in an increase in extended wing behavior, during which bees kept their wings out at right angles to their body rather than folded along their back. These data suggest that the GABA receptor types play distinct roles in behavior and that GABA may affect behavior at several different levels.
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Affiliation(s)
- Julie A Mustard
- Department of Biology, University of Texas Rio Grande Valley, Brownsville, TX 78520, USA.
| | - Lisa Jones
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Geraldine A Wright
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom; Department of Zoology, University of Oxford, Oxford OX1 3SZ, United Kingdom
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28
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Sanchez Bosch P, Makhijani K, Herboso L, Gold KS, Baginsky R, Woodcock KJ, Alexander B, Kukar K, Corcoran S, Jacobs T, Ouyang D, Wong C, Ramond EJV, Rhiner C, Moreno E, Lemaitre B, Geissmann F, Brückner K. Adult Drosophila Lack Hematopoiesis but Rely on a Blood Cell Reservoir at the Respiratory Epithelia to Relay Infection Signals to Surrounding Tissues. Dev Cell 2019; 51:787-803.e5. [PMID: 31735669 DOI: 10.1016/j.devcel.2019.10.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 08/08/2019] [Accepted: 10/17/2019] [Indexed: 12/23/2022]
Abstract
The use of adult Drosophila melanogaster as a model for hematopoiesis or organismal immunity has been debated. Addressing this question, we identify an extensive reservoir of blood cells (hemocytes) at the respiratory epithelia (tracheal air sacs) of the thorax and head. Lineage tracing and functional analyses demonstrate that the majority of adult hemocytes are phagocytic macrophages (plasmatocytes) from the embryonic lineage that parallels vertebrate tissue macrophages. Surprisingly, we find no sign of adult hemocyte expansion. Instead, hemocytes play a role in relaying an innate immune response to the blood cell reservoir: through Imd signaling and the Jak/Stat pathway ligand Upd3, hemocytes act as sentinels of bacterial infection, inducing expression of the antimicrobial peptide Drosocin in respiratory epithelia and colocalizing fat body domains. Drosocin expression in turn promotes animal survival after infection. Our work identifies a multi-signal relay of organismal humoral immunity, establishing adult Drosophila as model for inter-organ immunity.
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Affiliation(s)
- Pablo Sanchez Bosch
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Kalpana Makhijani
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Leire Herboso
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Katrina S Gold
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Rowan Baginsky
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | | | - Brandy Alexander
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Katelyn Kukar
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Sean Corcoran
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Thea Jacobs
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Debra Ouyang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Corinna Wong
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | | | | | | | | | - Frederic Geissmann
- King's College London, London, UK; Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Katja Brückner
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, USA; Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA; Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
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29
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Yan C, Wang F, Peng Y, Williams CR, Jenkins B, Wildonger J, Kim HJ, Perr JB, Vaughan JC, Kern ME, Falvo MR, O'Brien ET, Superfine R, Tuthill JC, Xiang Y, Rogers SL, Parrish JZ. Microtubule Acetylation Is Required for Mechanosensation in Drosophila. Cell Rep 2019; 25:1051-1065.e6. [PMID: 30355484 DOI: 10.1016/j.celrep.2018.09.075] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 08/04/2018] [Accepted: 09/24/2018] [Indexed: 01/13/2023] Open
Abstract
At the cellular level, α-tubulin acetylation alters the structure of microtubules to render them mechanically resistant to compressive forces. How this biochemical property of microtubule acetylation relates to mechanosensation remains unknown, although prior studies have shown that microtubule acetylation influences touch perception. Here, we identify the major Drosophila α-tubulin acetylase (dTAT) and show that it plays key roles in several forms of mechanosensation. dTAT is highly expressed in the larval peripheral nervous system (PNS), but it is largely dispensable for neuronal morphogenesis. Mutation of the acetylase gene or the K40 acetylation site in α-tubulin impairs mechanical sensitivity in sensory neurons and behavioral responses to gentle touch, harsh touch, gravity, and vibration stimuli, but not noxious thermal stimulus. Finally, we show that dTAT is required for mechanically induced activation of NOMPC, a microtubule-associated transient receptor potential channel, and functions to maintain integrity of the microtubule cytoskeleton in response to mechanical stimulation.
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Affiliation(s)
- Connie Yan
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Fei Wang
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Yun Peng
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Claire R Williams
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Brian Jenkins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jill Wildonger
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hyeon-Jin Kim
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Jonathan B Perr
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA; Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Megan E Kern
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - Michael R Falvo
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - E Timothy O'Brien
- Department of Physics & Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - Richard Superfine
- Department of Applied and Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA
| | - John C Tuthill
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Yang Xiang
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Stephen L Rogers
- Department of Biology, Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, WA 98195, USA.
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30
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Lopez-Bellido R, Himmel NJ, Gutstein HB, Cox DN, Galko MJ. An assay for chemical nociception in Drosophila larvae. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190282. [PMID: 31544619 PMCID: PMC6790381 DOI: 10.1098/rstb.2019.0282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2019] [Indexed: 12/14/2022] Open
Abstract
Chemically induced nociception has not yet been studied intensively in genetically tractable models. Hence, our goal was to establish a Drosophila assay that can be used to study the cellular and molecular/genetic bases of chemically induced nociception. Drosophila larvae exposed to increasing concentrations of hydrochloric acid (HCl) produced an increasingly intense aversive rolling response. HCl (0.5%) was subthreshold and provoked no response. All classes of peripheral multidendritic (md) sensory neurons (classes I-IV) are required for full responsiveness to acid, with class IV making the largest contribution. At the cellular level, classes IV, III and I showed increases in calcium following acid exposure. In the central nervous system, Basin-4 second-order neurons are the key regulators of chemically induced nociception, with a slight contribution from other types. Finally, chemical nociception can be sensitized by tissue damage. Subthreshold HCl provoked chemical allodynia in larvae 4 h after physical puncture wounding. Pinch wounding and UV irradiation, which do not compromise the cuticle, did not cause chemical allodynia. In sum, we developed a novel assay to study chemically induced nociception in Drosophila larvae. This assay, combined with the high genetic resolving power of Drosophila, should improve our basic understanding of fundamental mechanisms of chemical nociception. This article is part of the Theo Murphy meeting issue 'Evolution of mechanisms and behaviour important for pain'.
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Affiliation(s)
- Roger Lopez-Bellido
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Nathaniel J. Himmel
- Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30303, USA
| | - Howard B. Gutstein
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30303, USA
| | - Michael J. Galko
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Neuroscience Graduate Program, The MD Anderson UT Health Graduate School of Biomedical Sciences, TX 77030, USA
- Genetics and Epigenetics Graduate Program, The MD Anderson UT Health Graduate School of Biomedical Sciences, TX 77030, USA
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31
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Peng JJ, Lin SH, Liu YT, Lin HC, Li TN, Yao CK. A circuit-dependent ROS feedback loop mediates glutamate excitotoxicity to sculpt the Drosophila motor system. eLife 2019; 8:47372. [PMID: 31318331 PMCID: PMC6682402 DOI: 10.7554/elife.47372] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/17/2019] [Indexed: 12/12/2022] Open
Abstract
Overproduction of reactive oxygen species (ROS) is known to mediate glutamate excitotoxicity in neurological diseases. However, how ROS burdens can influence neural circuit integrity remains unclear. Here, we investigate the impact of excitotoxicity induced by depletion of Drosophila Eaat1, an astrocytic glutamate transporter, on locomotor central pattern generator (CPG) activity, neuromuscular junction architecture, and motor function. We show that glutamate excitotoxicity triggers a circuit-dependent ROS feedback loop to sculpt the motor system. Excitotoxicity initially elevates ROS, thereby inactivating cholinergic interneurons and consequently changing CPG output activity to overexcite motor neurons and muscles. Remarkably, tonic motor neuron stimulation boosts muscular ROS, gradually dampening muscle contractility to feedback-enhance ROS accumulation in the CPG circuit and subsequently exacerbate circuit dysfunction. Ultimately, excess premotor excitation of motor neurons promotes ROS-activated stress signaling that alters neuromuscular junction architecture. Collectively, our results reveal that excitotoxicity-induced ROS can perturb motor system integrity through a circuit-dependent mechanism.
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Affiliation(s)
- Jhan-Jie Peng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Shih-Han Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Yu-Tzu Liu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan, Republic of China
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32
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Chandel I, Baker R, Nakamura N, Panin V. Live Imaging and Analysis of Muscle Contractions in Drosophila Embryo. J Vis Exp 2019. [PMID: 31355800 DOI: 10.3791/59404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Coordinated muscle contractions are a form of rhythmic behavior seen early during development in Drosophila embryos. Neuronal sensory feedback circuits are required to control this behavior. Failure to produce the rhythmic pattern of contractions can be indicative of neurological abnormalities. We previously found that defects in protein O-mannosylation, a posttranslational protein modification, affect the axon morphology of sensory neurons and result in abnormal coordinated muscle contractions in embryos. Here, we present a relatively simple method for recording and analyzing the pattern of peristaltic muscle contractions by live imaging of late stage embryos up to the point of hatching, which we used to characterize the muscle contraction phenotype of protein O-mannosyltransferase mutants. Data obtained from these recordings can be used to analyze muscle contraction waves, including frequency, direction of propagation and relative amplitude of muscle contractions at different body segments. We have also examined body posture and taken advantage of a fluorescent marker expressed specifically in muscles to accurately determine the position of the embryo midline. A similar approach can also be utilized to study various other behaviors during development, such as embryo rolling and hatching.
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Affiliation(s)
- Ishita Chandel
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Ryan Baker
- Department of Biochemistry and Biophysics, Texas A&M University
| | | | - Vlad Panin
- Department of Biochemistry and Biophysics, Texas A&M University;
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33
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Loveless J, Lagogiannis K, Webb B. Modelling the mechanics of exploration in larval Drosophila. PLoS Comput Biol 2019; 15:e1006635. [PMID: 31276489 PMCID: PMC6636753 DOI: 10.1371/journal.pcbi.1006635] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 07/17/2019] [Accepted: 11/08/2018] [Indexed: 12/03/2022] Open
Abstract
The Drosophila larva executes a stereotypical exploratory routine that appears to consist of stochastic alternation between straight peristaltic crawling and reorientation events through lateral bending. We present a model of larval mechanics for axial and transverse motion over a planar substrate, and use it to develop a simple, reflexive neuromuscular model from physical principles. The mechanical model represents the midline of the larva as a set of point masses which interact with each other via damped translational and torsional springs, and with the environment via sliding friction forces. The neuromuscular model consists of: 1. segmentally localised reflexes that amplify axial compression in order to counteract frictive energy losses, and 2. long-range mutual inhibition between reflexes in distant segments, enabling overall motion of the model larva relative to its substrate. In the absence of damping and driving, the mechanical model produces axial travelling waves, lateral oscillations, and unpredictable, chaotic deformations. The neuromuscular model counteracts friction to recover these motion patterns, giving rise to forward and backward peristalsis in addition to turning. Our model produces spontaneous exploration, even though the nervous system has no intrinsic pattern generating or decision making ability, and neither senses nor drives bending motions. Ultimately, our model suggests a novel view of larval exploration as a deterministic superdiffusion process which is mechanistically grounded in the chaotic mechanics of the body. We discuss how this may provide new interpretations for existing observations at the level of tissue-scale activity patterns and neural circuitry, and provide some experimental predictions that would test the extent to which the mechanisms we present translate to the real larva. We investigate the relationship between brain, body and environment in the exploratory behaviour of fruitfly larva. A larva crawls forward by propagating a wave of compression through its segmented body, and changes its crawling direction by bending to one side or the other. We show first that a purely mechanical model of the larva’s body can produce travelling compression waves, sideways bending, and unpredictable, chaotic motions. For this body to locomote through its environment, it is necessary to add a neuromuscular system to counteract the loss of energy due to friction, and to limit the simultaneous compression of segments. These simple additions allow our model larva to generate life-like forward and backward crawling as well as spontaneous turns, which occur without any direct sensing or control of reorientation. The unpredictability inherent in the larva’s physics causes the model to explore its environment, despite the lack of any neural mechanism for rhythm generation or for deciding when to switch from crawling to turning. Our model thus demonstrates how understanding body mechanics can generate and simplify neurobiological hypotheses as to how behaviour arises.
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Affiliation(s)
- Jane Loveless
- Institute for Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Konstantinos Lagogiannis
- Institute for Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- MRC Centre for Developmental Neurobiology, New Hunt’s House, King’s College London, London, United Kingdom
| | - Barbara Webb
- Institute for Perception, Action, and Behaviour, School of Informatics, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
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34
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Malloy CA, Somasundaram E, Omar A, Bhutto U, Medley M, Dzubuk N, Cooper RL. Pharmacological identification of cholinergic receptor subtypes: modulation of locomotion and neural circuit excitability in Drosophila larvae. Neuroscience 2019; 411:47-64. [DOI: 10.1016/j.neuroscience.2019.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/16/2019] [Accepted: 05/07/2019] [Indexed: 01/28/2023]
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35
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Held A, Major P, Sahin A, Reenan RA, Lipscombe D, Wharton KA. Circuit Dysfunction in SOD1-ALS Model First Detected in Sensory Feedback Prior to Motor Neuron Degeneration Is Alleviated by BMP Signaling. J Neurosci 2019; 39:2347-2364. [PMID: 30659087 PMCID: PMC6433758 DOI: 10.1523/jneurosci.1771-18.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 12/24/2018] [Accepted: 01/10/2019] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease for which the origin and underlying cellular defects are not fully understood. Although motor neuron degeneration is the signature feature of ALS, it is not clear whether motor neurons or other cells of the motor circuit are the site of disease initiation. To better understand the contribution of multiple cell types in ALS, we made use of a Drosophila Sod1G85R knock-in model, in which all cells harbor the disease allele. End-stage dSod1G85R animals of both sexes exhibit severe motor deficits with clear degeneration of motor neurons. Interestingly, earlier in dSod1G85R larvae, motor function is also compromised, but their motor neurons exhibit only subtle morphological and electrophysiological changes that are unlikely to cause the observed decrease in locomotion. We analyzed the intact motor circuit and identified a defect in sensory feedback that likely accounts for the altered motor activity of dSod1G85R We found cell-autonomous activation of bone morphogenetic protein signaling in proprioceptor sensory neurons which are critical for the relay of the contractile status of muscles back to the central nerve cord, completely rescues early-stage motor defects and partially rescue late-stage motor function to extend lifespan. Identification of a defect in sensory feedback as a potential initiating event in ALS motor dysfunction, coupled with the ability of modified proprioceptors to alleviate such motor deficits, underscores the critical role that nonmotor neurons play in disease progression and highlights their potential as a site to identify early-stage ALS biomarkers and for therapeutic intervention.SIGNIFICANCE STATEMENT At diagnosis, many cellular processes are already disrupted in the amyotrophic lateral sclerosis (ALS) patient. Identifying the initiating cellular events is critical for achieving an earlier diagnosis to slow or prevent disease progression. Our findings indicate that neurons relaying sensory information underlie early stage motor deficits in a Drosophila knock-in model of ALS that best replicates gene dosage in familial ALS (fALS). Importantly, studies on intact motor circuits revealed defects in sensory feedback before evidence of motor neuron degeneration. These findings strengthen our understanding of how neural circuit dysfunctions lead to neurodegeneration and, coupled with our demonstration that the activation of bone morphogenetic protein signaling in proprioceptors alleviates both early and late motor dysfunction, underscores the importance of considering nonmotor neurons as therapeutic targets.
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Affiliation(s)
- Aaron Held
- Department of Molecular Biology, Cell Biology and Biochemistry
- The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912
| | - Paxton Major
- Department of Molecular Biology, Cell Biology and Biochemistry
| | - Asli Sahin
- Department of Molecular Biology, Cell Biology and Biochemistry
| | - Robert A Reenan
- Department of Molecular Biology, Cell Biology and Biochemistry
| | - Diane Lipscombe
- Department of Neuroscience, and
- The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912
| | - Kristi A Wharton
- Department of Molecular Biology, Cell Biology and Biochemistry,
- The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, Rhode Island 02912
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36
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Abstract
Proprioceptive neurons provide feedback about body positions and movements that are critical for coordination. Two new studies have revealed sequential, direction-dependent changes in dendritic folding and activities of proprioceptive neurons in freely-moving Drosophila larvae.
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Affiliation(s)
- Craig Montell
- Department of Molecular, Cellular and Developmental Biology, and the Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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37
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Jiang N, Rasmussen JP, Clanton JA, Rosenberg MF, Luedke KP, Cronan MR, Parker ED, Kim HJ, Vaughan JC, Sagasti A, Parrish JZ. A conserved morphogenetic mechanism for epidermal ensheathment of nociceptive sensory neurites. eLife 2019; 8:42455. [PMID: 30855229 PMCID: PMC6450671 DOI: 10.7554/elife.42455] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 03/08/2019] [Indexed: 12/13/2022] Open
Abstract
Interactions between epithelial cells and neurons influence a range of sensory modalities including taste, touch, and smell. Vertebrate and invertebrate epidermal cells ensheath peripheral arbors of somatosensory neurons, including nociceptors, yet the developmental origins and functional roles of this ensheathment are largely unknown. Here, we describe an evolutionarily conserved morphogenetic mechanism for epidermal ensheathment of somatosensory neurites. We found that somatosensory neurons in Drosophila and zebrafish induce formation of epidermal sheaths, which wrap neurites of different types of neurons to different extents. Neurites induce formation of plasma membrane phosphatidylinositol 4,5-bisphosphate microdomains at nascent sheaths, followed by a filamentous actin network, and recruitment of junctional proteins that likely form autotypic junctions to seal sheaths. Finally, blocking epidermal sheath formation destabilized dendrite branches and reduced nociceptive sensitivity in Drosophila. Epidermal somatosensory neurite ensheathment is thus a deeply conserved cellular process that contributes to the morphogenesis and function of nociceptive sensory neurons. Humans and other animals perceive and interact with the outside world through their sensory nervous system. Nerve cells, acting as the body’s ‘telegraph wires’, convey signals from sensory organs – like the eyes – to the brain, which then processes this information and tells the body how to respond. There are different kinds of sensory nerve cells that carry different types of information, but they all associate closely with the tissues and organs they connect to the brain. Human skin contains sensory nerve cells, which underpin our senses of touch and pain. There is a highly specialized, complex connection between some of these nerve cells and cells in the skin: the skin cells wrap tightly around the nerve cells’ free ends, forming sheath-like structures. This ‘ensheathment’ process happens in a wide range of animals, including those with a backbone, like fish and humans, and those without, like insects. Ensheathment is thought to be important for the skin’s nerve cells to work properly. Yet it remains unclear how or when these connections first appear. Jiang et al. therefore wanted to determine the developmental origins of ensheathment and to find out if these were also similar in animals with and without backbones. Experiments using fruit fly and zebrafish embryos revealed that nerve cells, not skin cells, were responsible for forming and maintaining the sheaths. In embryos where groups of sensory nerve cells were selectively killed – either using a laser or by making the cells produce a toxin – ensheathment did not occur. Further studies, using a variety of microscopy techniques, revealed that the molecular machinery required to stabilize the sheaths was similar in both fish and flies, and therefore likely to be conserved across different groups of animals. Removing sheaths in fly embryos led to nerve cells becoming unstable; the animals were also less sensitive to touch. This confirmed that ensheathment was indeed necessary for sensory nerve cells to work properly. By revealing how ensheathment first emerges, these findings shed new light on how the sensory nervous system develops and how its activity is controlled. In humans, skin cells ensheath the nerve cells responsible for sensing pain. A better understanding of how ensheathments first arise could therefore lead to new avenues for treating chronic pain and related conditions.
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Affiliation(s)
- Nan Jiang
- Department of Biology, University of Washington, Seattle, United States
| | - Jeffrey P Rasmussen
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Joshua A Clanton
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Marci F Rosenberg
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Kory P Luedke
- Department of Biology, University of Washington, Seattle, United States
| | - Mark R Cronan
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Edward D Parker
- Department of Opthalmology, University of Washington, Seattle, United States
| | - Hyeon-Jin Kim
- Department of Chemistry, University of Washington, Seattle, United States.,Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, United States.,Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Alvaro Sagasti
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, United States
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38
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Piezo-like Gene Regulates Locomotion in Drosophila Larvae. Cell Rep 2019; 26:1369-1377.e4. [DOI: 10.1016/j.celrep.2019.01.055] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 12/16/2018] [Accepted: 01/14/2019] [Indexed: 12/21/2022] Open
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Clark SG, Graybeal LL, Bhattacharjee S, Thomas C, Bhattacharya S, Cox DN. Basal autophagy is required for promoting dendritic terminal branching in Drosophila sensory neurons. PLoS One 2018; 13:e0206743. [PMID: 30395636 PMCID: PMC6218061 DOI: 10.1371/journal.pone.0206743] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 10/18/2018] [Indexed: 01/22/2023] Open
Abstract
Dendrites function as the primary sites for synaptic input and integration with impairments in dendritic arborization being associated with dysfunctional neuronal circuitry. Post-mitotic neurons require high levels of basal autophagy to clear cytotoxic materials and autophagic dysfunction under native or cellular stress conditions has been linked to neuronal cell death as well as axo-dendritic degeneration. However, relatively little is known regarding the developmental role of basal autophagy in directing aspects of dendritic arborization or the mechanisms by which the autophagic machinery may be transcriptionally regulated to promote dendritic diversification. We demonstrate that autophagy-related (Atg) genes are positively regulated by the homeodomain transcription factor Cut, and that basal autophagy functions as a downstream effector pathway for Cut-mediated dendritic terminal branching in Drosophila multidendritic (md) sensory neurons. Further, loss of function analyses implicate Atg genes in promoting cell type-specific dendritic arborization and terminal branching, while gain of function studies suggest that excessive autophagy leads to dramatic reductions in dendritic complexity. We demonstrate that the Atg1 initiator kinase interacts with the dual leucine zipper kinase (DLK) pathway by negatively regulating the E3 ubiquitin ligase Highwire and positively regulating the MAPKKK Wallenda. Finally, autophagic induction partially rescues dendritic atrophy defects observed in a model of polyglutamine toxicity. Collectively, these studies implicate transcriptional control of basal autophagy in directing dendritic terminal branching and demonstrate the importance of homeostatic control of autophagic levels for dendritic arbor complexity under native or cellular stress conditions.
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Affiliation(s)
- Sarah G. Clark
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Lacey L. Graybeal
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
| | - Shatabdi Bhattacharjee
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Caroline Thomas
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
| | - Surajit Bhattacharya
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
- School of Systems Biology, Krasnow Institute for Advanced Study, George Mason University, Fairfax, Virginia, United States of America
- * E-mail:
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40
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Nithianandam V, Chien CT. Actin blobs prefigure dendrite branching sites. J Cell Biol 2018; 217:3731-3746. [PMID: 30042190 PMCID: PMC6168249 DOI: 10.1083/jcb.201711136] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/28/2018] [Accepted: 07/09/2018] [Indexed: 02/08/2023] Open
Abstract
Nithianandam and Chien show via in vivo imaging that a dynamic population of F-actin termed actin blobs propagates bidirectionally in dendrites and stalls at future branching sites. The F-actin–severing protein Tsr/cofilin is a regulator of actin blob dynamics and dendrite branching. The actin cytoskeleton provides structural stability and adaptability to the cell. Neuronal dendrites frequently undergo morphological changes by emanating, elongating, and withdrawing branches. However, the knowledge about actin dynamics in dendrites during these processes is limited. By performing in vivo imaging of F-actin markers, we found that F-actin was highly dynamic and heterogeneously distributed in dendritic shafts with enrichment at terminal dendrites. A dynamic F-actin population that we named actin blobs propagated bidirectionally at an average velocity of 1 µm/min. Interestingly, these actin blobs stalled at sites where new dendrites would branch out in minutes. Overstabilization of F-actin by the G15S mutant abolished actin blobs and dendrite branching. We identified the F-actin–severing protein Tsr/cofilin as a regulator of dynamic actin blobs and branching activity. Hence, actin blob localization at future branching sites represents a dendrite-branching mechanism to account for highly diversified dendritic morphology.
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Affiliation(s)
- Vanitha Nithianandam
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Cheng-Ting Chien
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan .,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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41
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Hassan A, Timerman Y, Hamdan R, Sela N, Avetisyan A, Halachmi N, Salzberg A. An RNAi Screen Identifies New Genes Required for Normal Morphogenesis of Larval Chordotonal Organs. G3 (BETHESDA, MD.) 2018; 8:1871-1884. [PMID: 29678948 PMCID: PMC5982817 DOI: 10.1534/g3.118.200218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/19/2018] [Indexed: 01/10/2023]
Abstract
The proprioceptive chordotonal organs (ChO) of a fly larva respond to mechanical stimuli generated by muscle contractions and consequent deformations of the cuticle. The ability of the ChO to sense the relative displacement of its epidermal attachment sites likely depends on the correct mechanical properties of the accessory (cap and ligament) and attachment cells that connect the sensory unit (neuron and scolopale cell) to the cuticle. The genetic programs dictating the development of ChO cells with unique morphologies and mechanical properties are largely unknown. Here we describe an RNAi screen that focused on the ChO's accessory and attachment cells and was performed in 2nd instar larvae to allow for phenotypic analysis of ChOs that had already experienced mechanical stresses during larval growth. Nearly one thousand strains carrying RNAi constructs targeting more than 500 candidate genes were screened for their effects on ChO morphogenesis. The screen identified 31 candidate genes whose knockdown within the ChO lineage disrupted various aspects of cell fate determination, cell differentiation, cellular morphogenesis and cell-cell attachment. Most interestingly, one phenotypic group consisted of genes that affected the response of specific ChO cell types to developmental organ stretching, leading to abnormal pattern of cell elongation. The 'cell elongation' group included the transcription factors Delilah and Stripe, implicating them for the first time in regulating the response of ChO cells to developmental stretching forces. Other genes found to affect the pattern of ChO cell elongation, such as αTub85E, β1Tub56D, Tbce, CCT8, mys, Rac1 and shot, represent putative effectors that link between cell-fate determinants and the realization of cell-specific mechanical properties.
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Affiliation(s)
- Abeer Hassan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Yael Timerman
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Rana Hamdan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Nitzan Sela
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Adel Avetisyan
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109601, Israel
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42
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Im SH, Patel AA, Cox DN, Galko MJ. Drosophila Insulin receptor regulates the persistence of injury-induced nociceptive sensitization. Dis Model Mech 2018; 11:dmm034231. [PMID: 29752280 PMCID: PMC5992604 DOI: 10.1242/dmm.034231] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/25/2018] [Indexed: 12/12/2022] Open
Abstract
Diabetes-associated nociceptive hypersensitivity affects diabetic patients with hard-to-treat chronic pain. Because multiple tissues are affected by systemic alterations in insulin signaling, the functional locus of insulin signaling in diabetes-associated hypersensitivity remains obscure. Here, we used Drosophila nociception/nociceptive sensitization assays to investigate the role of Insulin receptor (Insulin-like receptor, InR) in nociceptive hypersensitivity. InR mutant larvae exhibited mostly normal baseline thermal nociception (absence of injury) and normal acute thermal hypersensitivity following UV-induced injury. However, their acute thermal hypersensitivity persists and fails to return to baseline, unlike in controls. Remarkably, injury-induced persistent hypersensitivity is also observed in larvae that exhibit either type 1 or type 2 diabetes. Cell type-specific genetic analysis indicates that InR function is required in multidendritic sensory neurons including nociceptive class IV neurons. In these same nociceptive sensory neurons, only modest changes in dendritic morphology were observed in the InRRNAi -expressing and diabetic larvae. At the cellular level, InR-deficient nociceptive sensory neurons show elevated calcium responses after injury. Sensory neuron-specific expression of InR rescues the persistent thermal hypersensitivity of InR mutants and constitutive activation of InR in sensory neurons ameliorates the hypersensitivity observed with a type 2-like diabetic state. Our results suggest that a sensory neuron-specific function of InR regulates the persistence of injury-associated hypersensitivity. It is likely that this new system will be an informative genetically tractable model of diabetes-associated hypersensitivity.
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Affiliation(s)
- Seol Hee Im
- Department of Genetics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
| | - Atit A Patel
- Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30303, USA
| | - Daniel N Cox
- Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30303, USA
| | - Michael J Galko
- Department of Genetics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
- Genetics and Epigenetics Graduate Program, University of Texas Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, TX 77030, USA
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43
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Clark MQ, Zarin AA, Carreira-Rosario A, Doe CQ. Neural circuits driving larval locomotion in Drosophila. Neural Dev 2018; 13:6. [PMID: 29673388 PMCID: PMC5907184 DOI: 10.1186/s13064-018-0103-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/05/2018] [Indexed: 11/10/2022] Open
Abstract
More than 30 years of studies into Drosophila melanogaster neurogenesis have revealed fundamental insights into our understanding of axon guidance mechanisms, neural differentiation, and early cell fate decisions. What is less understood is how a group of neurons from disparate anterior-posterior axial positions, lineages and developmental periods of neurogenesis coalesce to form a functional circuit. Using neurogenetic techniques developed in Drosophila it is now possible to study the neural substrates of behavior at single cell resolution. New mapping tools described in this review, allow researchers to chart neural connectivity to better understand how an anatomically simple organism performs complex behaviors.
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Affiliation(s)
- Matthew Q Clark
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasedena, CA, 91125, USA
| | - Aref Arzan Zarin
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA
| | | | - Chris Q Doe
- Institute of Neuroscience, Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, 97403, USA.
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44
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Chung CG, Kwon MJ, Jeon KH, Hyeon DY, Han MH, Park JH, Cha IJ, Cho JH, Kim K, Rho S, Kim GR, Jeong H, Lee JW, Kim T, Kim K, Kim KP, Ehlers MD, Hwang D, Lee SB. Golgi Outpost Synthesis Impaired by Toxic Polyglutamine Proteins Contributes to Dendritic Pathology in Neurons. Cell Rep 2018; 20:356-369. [PMID: 28700938 DOI: 10.1016/j.celrep.2017.06.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 04/28/2017] [Accepted: 06/21/2017] [Indexed: 11/29/2022] Open
Abstract
Dendrite aberration is a common feature of neurodegenerative diseases caused by protein toxicity, but the underlying mechanisms remain largely elusive. Here, we show that nuclear polyglutamine (polyQ) toxicity resulted in defective terminal dendrite elongation accompanied by a loss of Golgi outposts (GOPs) and a decreased supply of plasma membrane (PM) in Drosophila class IV dendritic arborization (da) (C4 da) neurons. mRNA sequencing revealed that genes downregulated by polyQ proteins included many secretory pathway-related genes, including COPII genes regulating GOP synthesis. Transcription factor enrichment analysis identified CREB3L1/CrebA, which regulates COPII gene expression. CrebA overexpression in C4 da neurons restores the dysregulation of COPII genes, GOP synthesis, and PM supply. Chromatin immunoprecipitation (ChIP)-PCR revealed that CrebA expression is regulated by CREB-binding protein (CBP), which is sequestered by polyQ proteins. Furthermore, co-overexpression of CrebA and Rac1 synergistically restores the polyQ-induced dendrite pathology. Collectively, our results suggest that GOPs impaired by polyQ proteins contribute to dendrite pathology through the CBP-CrebA-COPII pathway.
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Affiliation(s)
- Chang Geon Chung
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Min Jee Kwon
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Keun Hye Jeon
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea; Department of Family Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea
| | - Do Young Hyeon
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang 37673, Republic of Korea
| | - Myeong Hoon Han
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Jeong Hyang Park
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - In Jun Cha
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Jae Ho Cho
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Kunhyung Kim
- Department of New Biology, DGIST, Daegu 42988, Republic of Korea
| | - Sangchul Rho
- Center for Plant Aging Research, Institute for Basic Science, DGIST, Daegu 42988, Republic of Korea
| | - Gyu Ree Kim
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea
| | - Hyobin Jeong
- Center for Plant Aging Research, Institute for Basic Science, DGIST, Daegu 42988, Republic of Korea
| | - Jae Won Lee
- Department of Applied Chemistry, Institute of Natural Science, College of Applied Science, Kyung Hee University, Yongin 17104, Republic of Korea
| | - TaeSoo Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Keetae Kim
- Department of New Biology, DGIST, Daegu 42988, Republic of Korea
| | - Kwang Pyo Kim
- Department of Applied Chemistry, Institute of Natural Science, College of Applied Science, Kyung Hee University, Yongin 17104, Republic of Korea
| | | | - Daehee Hwang
- School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang 37673, Republic of Korea; Department of New Biology, DGIST, Daegu 42988, Republic of Korea; Center for Plant Aging Research, Institute for Basic Science, DGIST, Daegu 42988, Republic of Korea.
| | - Sung Bae Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Republic of Korea.
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45
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Zhou J, Du X, Berciu C, Del Signore SJ, Chen X, Yamagata N, Rodal AA, Nicastro D, Xu B. Cellular Uptake of A Taurine-Modified, Ester Bond-Decorated D-Peptide Derivative via Dynamin-Based Endocytosis and Macropinocytosis. Mol Ther 2018; 26:648-658. [PMID: 29396265 DOI: 10.1016/j.ymthe.2017.11.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 11/06/2017] [Accepted: 11/10/2017] [Indexed: 11/16/2022] Open
Abstract
Most of the peptides used for promoting cellular uptake bear positive charges. In our previous study, we reported an example of taurine (bearing negative charges in physiological conditions) promoting cellular uptake of D-peptides. Taurine, conjugated to a small D-peptide via an ester bond, promotes the cellular uptake of this D-peptide. Particularly, intracellular carboxylesterase (CES) instructs the D-peptide to self-assemble and to form nanofibers, which largely disfavors efflux and further enhances the intracellular accumulation of the D-peptide, as supported by that the addition of CES inhibitors partially impaired cellular uptake of this molecule in mammalian cell lines. Using dynamin 1, 2, and 3 triple knockout (TKO) mouse fibroblasts, we demonstrated that cells took up this molecule via macropinocytosis and dynamin-dependent endocytosis. Imaging of Drosophila larval blood cells derived from endocytic mutants confirmed the involvement of multiple endocytosis pathways. Electron microscopy (EM) indicated that the precursors can form aggregates on the cell surface to facilitate the cellular uptake via macropinocytosis. EM also revealed significantly increased numbers of vesicles in the cytosol. This work provides new insights into the cellular uptake of taurine derivative for intracellular delivery and self-assembly of D-peptides.
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Affiliation(s)
- Jie Zhou
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Xuewen Du
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Cristina Berciu
- Department of Biology, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Steven J Del Signore
- Department of Biology, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Xiaoyi Chen
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Natsuko Yamagata
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Avital A Rodal
- Department of Biology, Brandeis University, 415 South St., Waltham, MA 02453, USA
| | - Daniela Nicastro
- Department of Biology, Brandeis University, 415 South St., Waltham, MA 02453, USA; Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bing Xu
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02453, USA.
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46
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Chongtham A, Barbaro B, Filip T, Syed A, Huang W, Smith MR, Marsh JL. Nonmammalian Models of Huntington's Disease. Methods Mol Biol 2018; 1780:75-96. [PMID: 29856015 DOI: 10.1007/978-1-4939-7825-0_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Flies, worms, yeast and more recently zebra fish have all been engineered to express expanded polyglutamine repeat versions of Huntingtin with various resulting pathologies including early death, neurodegeneration, and loss of motor function. Each of these models present particular features that make it useful in studying the mechanisms of polyglutamine pathology. However, one particular unbiased readout of mHTT pathology is functional loss of motor control. Loss of motor control is prominent in patients, but it remains unresolved whether pathogenic symptoms in patients result from overt degeneration and loss of neurons or from malfunctioning of surviving neurons as the pathogenic insult builds up. This is why a functional assay such as motor control can be uniquely powerful in revealing early as well as late neurological deficits and does not rely on assumptions such as that the level of inclusions or the degree of neuronal loss can be equated with the level of pathology. Drosophila is well suited for such assays because it contains a functioning nervous system with many parallels to the human condition. In addition, the ability to readily express mHTT transgenes in different tissues and subsets of neurons allows one the possibility of isolating a particular effect to a subset of neurons where one can correlate subcellular events in response to mHTT challenge with pathology at both the cellular and organismal levels. Here we describe methods to monitor the degree of motor function disruption in Drosophila models of HD and we include a brief summary of other nonmammalian models of HD and discussion of their unique strengths.
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Affiliation(s)
- Anjalika Chongtham
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA
| | - Brett Barbaro
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA.,The Scripps Research Institute, La Jolla, CA, USA
| | - Tomas Filip
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA.,Biology Centre Czech Acad. Sci., Ceske Budejovice, Czech Republic
| | - Adeela Syed
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA
| | - Weijian Huang
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA
| | - Marianne R Smith
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA.,University Advancement, UC Irvine, Irvine, CA, USA
| | - J Lawrence Marsh
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, 92697, CA, USA.
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47
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Protein O-Mannosyltransferases Affect Sensory Axon Wiring and Dynamic Chirality of Body Posture in the Drosophila Embryo. J Neurosci 2017; 38:1850-1865. [PMID: 29167399 DOI: 10.1523/jneurosci.0346-17.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 02/06/2023] Open
Abstract
Genetic defects in protein O-mannosyltransferase 1 (POMT1) and POMT2 underlie severe muscular dystrophies. POMT genes are evolutionarily conserved in metazoan organisms. In Drosophila, both male and female POMT mutants show a clockwise rotation of adult abdominal segments, suggesting a chirality of underlying pathogenic mechanisms. Here we described and analyzed a similar phenotype in POMT mutant embryos that shows left-handed body torsion. Our experiments demonstrated that coordinated muscle contraction waves are associated with asymmetric embryo rolling, unveiling a new chirality marker in Drosophila development. Using genetic and live-imaging approaches, we revealed that the torsion phenotype results from differential rolling and aberrant patterning of peristaltic waves of muscle contractions. Our results demonstrated that peripheral sensory neurons are required for normal contractions that prevent the accumulation of torsion. We found that POMT mutants show abnormal axonal connections of sensory neurons. POMT transgenic expression limited to sensory neurons significantly rescued the torsion phenotype, axonal connectivity defects, and abnormal contractions in POMT mutant embryos. Together, our data suggested that protein O-mannosylation is required for normal sensory feedback to control coordinated muscle contractions and body posture. This mechanism may shed light on analogous functions of POMT genes in mammals and help to elucidate the etiology of neurological defects in muscular dystrophies.SIGNIFICANCE STATEMENT Protein O-mannosyltransferases (POMTs) are evolutionarily conserved in metazoans. Mutations in POMTs cause severe muscular dystrophies associated with pronounced neurological defects. However, neurological functions of POMTs remain poorly understood. We demonstrated that POMT mutations in Drosophila result in abnormal muscle contractions and cause embryo torsion. Our experiments uncovered a chirality of embryo movements and a unique POMT-dependent mechanism that maintains symmetry of a developing system affected by chiral forces. Furthermore, POMTs were found to be required for proper axon connectivity of sensory neurons, suggesting that O-mannosylation regulates the sensory feedback controlling muscle contractions. This novel POMT function in the peripheral nervous system may shed light on analogous functions in mammals and help to elucidate pathomechanisms of neurological abnormalities in muscular dystrophies.
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Regulation of Drosophila hematopoietic sites by Activin-β from active sensory neurons. Nat Commun 2017; 8:15990. [PMID: 28748922 PMCID: PMC5537569 DOI: 10.1038/ncomms15990] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 05/23/2017] [Indexed: 12/21/2022] Open
Abstract
An outstanding question in animal development, tissue homeostasis and disease is how cell populations adapt to sensory inputs. During Drosophila larval development, hematopoietic sites are in direct contact with sensory neuron clusters of the peripheral nervous system (PNS), and blood cells (hemocytes) require the PNS for their survival and recruitment to these microenvironments, known as Hematopoietic Pockets. Here we report that Activin-β, a TGF-β family ligand, is expressed by sensory neurons of the PNS and regulates the proliferation and adhesion of hemocytes. These hemocyte responses depend on PNS activity, as shown by agonist treatment and transient silencing of sensory neurons. Activin-β has a key role in this regulation, which is apparent from reporter expression and mutant analyses. This mechanism of local sensory neurons controlling blood cell adaptation invites evolutionary parallels with vertebrate hematopoietic progenitors and the independent myeloid system of tissue macrophages, whose regulation by local microenvironments remain undefined.
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Sensory integration and neuromodulatory feedback facilitate Drosophila mechanonociceptive behavior. Nat Neurosci 2017; 20:1085-1095. [PMID: 28604684 PMCID: PMC5931224 DOI: 10.1038/nn.4580] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 05/01/2017] [Indexed: 12/17/2022]
Abstract
Nociception is an evolutionary conserved mechanism to encode and process harmful environmental stimuli. Like most animals, Drosophila larvae respond to a variety of nociceptive stimuli, including noxious touch and temperature, with a stereotyped escape response through activation of multimodal nociceptors. How behavioral responses to these different modalities are processed and integrated by the downstream network remains poorly understood. By combining transsynaptic labeling, ultrastructural analysis, calcium imaging, optogenetic and behavioral analyses, we uncovered a circuit specific for mechano- but not thermo-nociception. Interestingly, integration of mechanosensory input from innocuous and nociceptive sensory neurons is required for robust mechano-nociceptive responses. We further show that neurons integrating mechanosensory input facilitate primary nociceptive output via releasing short Neuropeptide F (sNPF), the Drosophila Neuropeptide Y (NPY) homolog. Our findings unveil how integration of somatosensory input and neuropeptide-mediated modulation can produce robust modality-specific escape behavior.
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Pathogenic Huntington Alters BMP Signaling and Synaptic Growth through Local Disruptions of Endosomal Compartments. J Neurosci 2017; 37:3425-3439. [PMID: 28235896 DOI: 10.1523/jneurosci.2752-16.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 02/07/2017] [Accepted: 02/13/2017] [Indexed: 01/05/2023] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by expansion of a polyglutamine (polyQ) stretch within the Huntingtin (Htt) protein. Pathogenic Htt disrupts multiple neuronal processes, including gene expression, axonal trafficking, proteasome and mitochondrial activity, and intracellular vesicle trafficking. However, the primary pathogenic mechanism and subcellular site of action for mutant Htt are still unclear. Using a Drosophila HD model, we found that pathogenic Htt expression leads to a profound overgrowth of synaptic connections that correlates directly with the levels of Htt at nerve terminals. Branches of the same nerve containing different levels of Htt show distinct phenotypes, indicating that Htt acts locally to disrupt synaptic growth. The effects of pathogenic Htt on synaptic growth arise from defective synaptic endosomal trafficking, leading to expansion of a recycling endosomal signaling compartment containing Sorting Nexin 16 and a reduction in late endosomes containing Rab11. The disruption of endosomal compartments leads to elevated BMP signaling within nerve terminals, driving excessive synaptic growth. Blocking aberrant signaling from endosomes or reducing BMP activity ameliorates the severity of HD pathology and improves viability. Pathogenic Htt is present largely in a nonaggregated form at synapses, indicating that cytosolic forms of the protein are likely to be the toxic species that disrupt endosomal signaling. Our data indicate that pathogenic Htt acts locally at nerve terminals to alter trafficking between endosomal compartments, leading to defects in synaptic structure that correlate with pathogenesis and lethality in the Drosophila HD model.SIGNIFICANCE STATEMENT Huntington's disease (HD) is the most commonly inherited polyglutamine expansion disorder, but how mutant Huntingtin (Htt) disrupts neuronal function is unclear. In particular, it is unknown within what subcellular compartment pathogenic Htt acts and whether the pathogenesis is associated with aggregated or more soluble forms of the protein. Using a Drosophila HD model, we find that nonaggregated pathogenic Htt acts locally at synaptic terminals to disrupt endosomal compartments, leading to aberrant wiring defects. Genetic manipulations to increase endosomal trafficking of synaptic growth receptors from signaling endosomes or to reduce BMP signaling reduce pathology in this HD model. These data indicate that pathogenic Htt can act locally within nerve terminals to disrupt synaptic endosomal signaling and induce neuropathology.
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