1
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Jeong S. Function and regulation of nitric oxide signaling in Drosophila. Mol Cells 2024; 47:100006. [PMID: 38218653 PMCID: PMC10880079 DOI: 10.1016/j.mocell.2023.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 01/15/2024] Open
Abstract
Nitric oxide (NO) serves as an evolutionarily conserved signaling molecule that plays an important role in a wide variety of cellular processes. Extensive studies in Drosophila melanogaster have revealed that NO signaling is required for development, physiology, and stress responses in many different types of cells. In neuronal cells, multiple NO signaling pathways appear to operate in different combinations to regulate learning and memory formation, synaptic transmission, selective synaptic connections, axon degeneration, and axon regrowth. During organ development, elevated NO signaling suppresses cell cycle progression, whereas downregulated NO leads to an increase in larval body size via modulation of hormone signaling. The most striking feature of the Drosophila NO synthase is that various stressors, such as neuropeptides, aberrant proteins, hypoxia, bacterial infection, and mechanical injury, can activate Drosophila NO synthase, initially regulating cellular physiology to enable cells to survive. However, under severe stress or pathophysiological conditions, high levels of NO promote regulated cell death and the development of neurodegenerative diseases. In this review, I highlight and discuss the current understanding of molecular mechanisms by which NO signaling regulates distinct cellular functions and behaviors.
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Affiliation(s)
- Sangyun Jeong
- Department of Molecular Biology, Department of Bioactive Material Sciences, and Research Center of Bioactive Materials, Jeonbuk National University, Jeonju, Jeollabukdo 54896, Republic of Korea.
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2
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Guangming G, Mei C, Qinfeng Y, Xiang G, Chenchen Z, Qingyuan S, Wei X, Junhua G. Neurexin and neuroligins jointly regulate synaptic degeneration at the Drosophila neuromuscular junction based on TEM studies. Front Cell Neurosci 2023; 17:1257347. [PMID: 38026694 PMCID: PMC10646337 DOI: 10.3389/fncel.2023.1257347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/12/2023] [Indexed: 12/01/2023] Open
Abstract
The Drosophila larval neuromuscular junction (NMJ) is a well-known model system and is often used to study synapse development. Here, we show synaptic degeneration at NMJ boutons, primarily based on transmission electron microscopy (TEM) studies. When degeneration starts, the subsynaptic reticulum (SSR) swells, retracts and folds inward, and the residual SSR then degenerates into a disordered, thin or linear membrane. The axon terminal begins to degenerate from the central region, and the T-bar detaches from the presynaptic membrane with clustered synaptic vesicles to accelerate large-scale degeneration. There are two degeneration modes for clear synaptic vesicles. In the first mode, synaptic vesicles without actin filaments degenerate on the membrane with ultrafine spots and collapse and disperse to form an irregular profile with dark ultrafine particles. In the second mode, clear synaptic vesicles with actin filaments degenerate into dense synaptic vesicles, form irregular dark clumps without a membrane, and collapse and disperse to form an irregular profile with dark ultrafine particles. Last, all residual membranes in NMJ boutons degenerate into a linear shape, and all the residual elements in axon terminals degenerate and eventually form a cluster of dark ultrafine particles. Swelling and retraction of the SSR occurs prior to degradation of the axon terminal, which degenerates faster and with more intensity than the SSR. NMJ bouton degeneration occurs under normal physiological conditions but is accelerated in Drosophila neurexin (dnrx) dnrx273, Drosophila neuroligin (dnlg) dnlg1 and dnlg4 mutants and dnrx83;dnlg3 and dnlg2;dnlg3 double mutants, which suggests that both neurexin and neuroligins play a vital role in preventing synaptic degeneration.
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Affiliation(s)
- Gan Guangming
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Chen Mei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Yu Qinfeng
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Gao Xiang
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Zhang Chenchen
- School of Medicine, Southeast University, Nanjing, Jiangsu, China
| | - Sheng Qingyuan
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
| | - Xie Wei
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- The Collaborative Innovation Center for Brain Science, Southeast University, Nanjing, Jiangsu, China
| | - Geng Junhua
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu, China
- Shenzhen Research Institute of Southeast University, Shenzhen, Guangdong, China
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3
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Tsuboguchi S, Nakamura Y, Ishihara T, Kato T, Sato T, Koyama A, Mori H, Koike Y, Onodera O, Ueno M. TDP-43 differentially propagates to induce antero- and retrograde degeneration in the corticospinal circuits in mouse focal ALS models. Acta Neuropathol 2023; 146:611-629. [PMID: 37555859 DOI: 10.1007/s00401-023-02615-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 06/22/2023] [Accepted: 07/15/2023] [Indexed: 08/10/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by TDP-43 inclusions in the cortical and spinal motor neurons. It remains unknown whether and how pathogenic TDP-43 spreads across neural connections to progress degenerative processes in the cortico-spinal motor circuitry. Here we established novel mouse ALS models that initially induced mutant TDP-43 inclusions in specific neuronal or cell types in the motor circuits, and investigated whether TDP-43 and relevant pathological processes spread across neuronal or cellular connections. We first developed ALS models that primarily induced TDP-43 inclusions in the corticospinal neurons, spinal motor neurons, or forelimb skeletal muscle, by using adeno-associated virus (AAV) expressing mutant TDP-43. We found that TDP-43 induced in the corticospinal neurons was transported along the axons anterogradely and transferred to the oligodendrocytes along the corticospinal tract (CST), coinciding with mild axon degeneration. In contrast, TDP-43 introduced in the spinal motor neurons did not spread retrogradely to the cortical or spinal neurons; however, it induced an extreme loss of spinal motor neurons and subsequent degeneration of neighboring spinal neurons, suggesting a degenerative propagation in a retrograde manner in the spinal cord. The intraspinal degeneration further led to severe muscle atrophy. Finally, TDP-43 induced in the skeletal muscle did not propagate pathological events to spinal neurons retrogradely. Our data revealed that mutant TDP-43 spread across neuro-glial connections anterogradely in the corticospinal pathway, whereas it exhibited different retrograde degenerative properties in the spinal circuits. This suggests that pathogenic TDP-43 may induce distinct antero- and retrograde mechanisms of degeneration in the motor system in ALS.
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Affiliation(s)
- Shintaro Tsuboguchi
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Niigata, 951-8585, Japan
| | - Yuka Nakamura
- Department of System Pathology for Neurological Disorders, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Niigata, 951-8585, Japan
| | - Taisuke Kato
- Department of Molecular Neuroscience, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tokiharu Sato
- Department of System Pathology for Neurological Disorders, Brain Research Institute, Niigata University, Niigata, Japan
| | - Akihide Koyama
- Division of Legal Medicine, Graduate School of Medicine and Dental Sciences, Niigata University, Niigata, Japan
| | - Hideki Mori
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Niigata, 951-8585, Japan
| | - Yuka Koike
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Niigata, 951-8585, Japan
| | - Osamu Onodera
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, Niigata, 951-8585, Japan.
- Department of Molecular Neuroscience, Brain Research Institute, Niigata University, Niigata, Japan.
| | - Masaki Ueno
- Department of System Pathology for Neurological Disorders, Brain Research Institute, Niigata University, Niigata, Japan.
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4
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Perron C, Carme P, Rosell AL, Minnaert E, Ruiz-Demoulin S, Szczkowski H, Neukomm LJ, Dura JM, Boulanger A. Chemokine-like Orion is involved in the transformation of glial cells into phagocytes in different developmental neuronal remodeling paradigms. Development 2023; 150:dev201633. [PMID: 37767633 PMCID: PMC10565233 DOI: 10.1242/dev.201633] [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: 01/20/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023]
Abstract
During animal development, neurons often form exuberant or inappropriate axons and dendrites at early stages, followed by the refinement of neuronal circuits at late stages. Neural circuit refinement leads to the production of neuronal debris in the form of neuronal cell corpses, fragmented axons and dendrites, and pruned synapses requiring disposal. Glial cells act as predominant phagocytes during neuronal remodeling and degeneration, and crucial signaling pathways between neurons and glia are necessary for the execution of phagocytosis. Chemokine-like mushroom body neuron-secreted Orion is essential for astrocyte infiltration into the γ axon bundle leading to γ axon pruning. Here, we show a role of Orion in debris engulfment and phagocytosis in Drosophila. Interestingly, Orion is involved in the overall transformation of astrocytes into phagocytes. In addition, analysis of several neuronal paradigms demonstrates the role of Orion in eliminating both peptidergic vCrz+ and PDF-Tri neurons via additional phagocytic glial cells like cortex and/or ensheathing glia. Our results suggest that Orion is essential for phagocytic activation of astrocytes, cortex and ensheathing glia, and point to Orion as a trigger of glial infiltration, engulfment and phagocytosis.
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Affiliation(s)
| | - Pascal Carme
- IGH, Univ Montpellier, CNRS, Montpellier, France
| | - Arnau Llobet Rosell
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Eva Minnaert
- IGH, Univ Montpellier, CNRS, Montpellier, France
| | | | | | - Lukas Jakob Neukomm
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
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5
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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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6
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Xu W, Kong W, Gao Z, Huang E, Xie W, Wang S, Rui M. Establishment of a novel axon pruning model of Drosophila motor neuron. Biol Open 2023; 12:286282. [PMID: 36606515 PMCID: PMC9838636 DOI: 10.1242/bio.059535] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 11/30/2022] [Indexed: 01/07/2023] Open
Abstract
Developmental neuronal pruning is a process by which neurons selectively remove excessive or unnecessary neurite without causing neuronal death. Importantly, this process is widely used for the refinement of neural circuits in both vertebrates and invertebrates, and may also contribute to the pathogenesis of neuropsychiatric disorders, such as autism and schizophrenia. In the peripheral nervous system (PNS), class IV dendritic arborization (da) sensory neurons of Drosophila, selectively remove the dendrites without losing their somas and axons, while the dendrites and axons of mushroom body (MB) γ neuron in the central nervous system (CNS) are eliminated by localized fragmentation during metamorphosis. Alternatively, dendrite pruning of ddaC neurons is usually investigated via live-cell imaging, while dissection and fixation are currently used for evaluating MB γ neuron axon pruning. Thus, an excellent model system to assess axon specific pruning directly via live-cell imaging remains elusive. Here, we report that the Drosophila motor neuron offers a unique advantage for studying axon pruning. Interestingly, we uncover that long-range projecting axon bundle from soma at ventral nerve cord (VNC), undergoes degeneration rather than retraction during metamorphosis. Strikingly, the pruning process of the motor axon bundle is straightforward to investigate via live imaging and it occurs approximately at 22 h after pupal formation (APF), when axon bundles are completely cleared. Consistently, the classical axon pruning regulators in the Drosophila MB γ neuron, including TGF-β signaling, ecdysone signaling, JNK signaling, and the ubiquitin-proteasome system are also involved in governing motor axon pruning. Finally, our findings establish an unprecedented axon pruning mode that will serve to systematically screen and identify undiscovered axon pruning regulators. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Wanyue Xu
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China
| | - Weiyu Kong
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China
| | - Ziyang Gao
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China
| | - Erqian Huang
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China
| | - Wei Xie
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China
| | - Su Wang
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China,Authors for correspondence (; )
| | - Menglong Rui
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China,Authors for correspondence (; )
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7
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Shuster SA, Li J, Chon UR, Sinantha-Hu MC, Luginbuhl DJ, Udeshi ND, Carey DK, Takeo YH, Xie Q, Xu C, Mani DR, Han S, Ting AY, Carr SA, Luo L. In situ cell-type-specific cell-surface proteomic profiling in mice. Neuron 2022; 110:3882-3896.e9. [PMID: 36220098 PMCID: PMC9742329 DOI: 10.1016/j.neuron.2022.09.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/04/2022] [Accepted: 09/20/2022] [Indexed: 11/06/2022]
Abstract
Cell-surface proteins (CSPs) mediate intercellular communication throughout the lives of multicellular organisms. However, there are no generalizable methods for quantitative CSP profiling in specific cell types in vertebrate tissues. Here, we present in situ cell-surface proteome extraction by extracellular labeling (iPEEL), a proximity labeling method in mice that enables spatiotemporally precise labeling of cell-surface proteomes in a cell-type-specific environment in native tissues for discovery proteomics. Applying iPEEL to developing and mature cerebellar Purkinje cells revealed differential enrichment in CSPs with post-translational protein processing and synaptic functions in the developing and mature cell-surface proteomes, respectively. A proteome-instructed in vivo loss-of-function screen identified a critical, multifaceted role for Armh4 in Purkinje cell dendrite morphogenesis. Armh4 overexpression also disrupts dendrite morphogenesis; this effect requires its conserved cytoplasmic domain and is augmented by disrupting its endocytosis. Our results highlight the utility of CSP profiling in native mammalian tissues for identifying regulators of cell-surface signaling.
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Affiliation(s)
- S Andrew Shuster
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - URee Chon
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Miley C Sinantha-Hu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Yukari H Takeo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Neurosciences Program, Stanford University, CA 94305, USA
| | - Chuanyun Xu
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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8
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Cabrera OH, Useinovic N, Maksimovic S, Near M, Quillinan N, Todorovic SM, Jevtovic-Todorovic V. Neonatal ketamine exposure impairs infrapyramidal bundle pruning and causes lasting increase in excitatory synaptic transmission in hippocampal CA3 neurons. Neurobiol Dis 2022; 175:105923. [PMID: 36371060 PMCID: PMC9831613 DOI: 10.1016/j.nbd.2022.105923] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 10/27/2022] [Accepted: 11/07/2022] [Indexed: 11/11/2022] Open
Abstract
Preclinical models demonstrate that nearly all anesthetics cause widespread neuroapoptosis in the developing brains of infant rodents and non-human primates. Anesthesia-induced developmental apoptosis is succeeded by prolonged neuropathology in the surviving neurons and lasting cognitive impairments, suggesting that anesthetics interfere with the normal developmental trajectory of the brain. However, little is known about effects of anesthetics on stereotyped axonal pruning, an important developmental algorithm that sculpts neural circuits for proper function. Here, we proposed that neonatal ketamine exposure may interfere with stereotyped axonal pruning of the infrapyramidal bundle (IPB) of the hippocampal mossy fiber system and that impaired pruning may be associated with alterations in the synaptic transmission of CA3 neurons. To test this hypothesis, we injected postnatal day 7 (PND7) mouse pups with ketamine or vehicle over 6 h and then studied them at different developmental stages corresponding to IPB pruning (PND20-40). Immunohistochemistry with synaptoporin (a marker of mossy fibers) revealed that in juvenile mice treated with ketamine at PND7, but not in vehicle-treated controls, positive IPB fibers extended farther into the stratum pyramidale of CA3 region. Furthermore, immunofluorescent double labeling for synaptoporin and PSD-95 strongly suggested that the unpruned IPB caused by neonatal ketamine exposure makes functional synapses. Importantly, patch-clamp electrophysiology for miniature excitatory postsynaptic currents (mEPSCs) in acute brain slices ex vivo revealed increased frequency and amplitudes of mEPSCs in hippocampal CA3 neurons in ketamine-treated groups when compared to vehicle controls. We conclude that neonatal ketamine exposure interferes with normal neural circuit development and that this interference leads to lasting increase in excitatory synaptic transmission in hippocampus.
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Affiliation(s)
- Omar Hoseá Cabrera
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA
| | - Nemanja Useinovic
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA
| | - Stefan Maksimovic
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA
| | - Michelle Near
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA
| | - Nidia Quillinan
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA,University of Colorado School of Medicine at Anschutz Medical Campus, Neuroscience Graduate Program, Aurora, CO, USA
| | - Slobodan M. Todorovic
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA,University of Colorado School of Medicine at Anschutz Medical Campus, Neuroscience Graduate Program, Aurora, CO, USA
| | - Vesna Jevtovic-Todorovic
- University of Colorado School of Medicine at Anschutz Medical Campus, Department of Anesthesiology, Aurora, CO, USA,University of Colorado School of Medicine at Anschutz Medical Campus, Department of Pharmacology, Aurora, CO, USA,Corresponding author. (V. Jevtovic-Todorovic)
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9
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Khan TA, Guo A, Martin J, Te Chien C, Liu T, Szczurkowska J, Shelly M. Directed mechanisms for apical dendrite development during neuronal polarization. Dev Biol 2022; 490:110-116. [PMID: 35809631 DOI: 10.1016/j.ydbio.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 06/09/2022] [Accepted: 07/01/2022] [Indexed: 12/18/2022]
Abstract
The development of the dendrite and the axon during neuronal polarization underlies the directed flow of information in the brain. Seminal studies on axon development have dominated the mechanistic analysis of neuronal polarization. These studies, many originating from examinations in cultured hippocampal and cortical neurons in vitro, have established a prevalent view that axon formation precedes and is necessary for neuronal polarization. There is also in vivo evidence supporting this view. Nevertheless, the establishment of bipolar polarity and the leading edge, and apical dendrite development in pyramidal neurons in vivo occur when axon formation is prevented. Furthermore, recent mounting evidence suggest that directed mechanisms might mediate bipolar polarity/leading process and subsequent apical dendrite development. In the presence of spatially directed extracellular cues in the developing brain, these events may operate independently of axon forming events. In this perspective we summarize evidence in support of these evolving views in neuronal polarization and highlight recent findings on dedicated mechanisms acting in apical dendrite development.
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Affiliation(s)
- Tamor A Khan
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Alan Guo
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Jacqueline Martin
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Chia Te Chien
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Tianrui Liu
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Joanna Szczurkowska
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA
| | - Maya Shelly
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794-5230, USA.
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10
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Mehl LC, Manjally AV, Bouadi O, Gibson EM, Tay TL. Microglia in brain development and regeneration. Development 2022; 149:275253. [PMID: 35502782 PMCID: PMC9124570 DOI: 10.1242/dev.200425] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It has recently emerged that microglia, the tissue-resident macrophages of the central nervous system, play significant non-innate immune roles to support the development, maintenance, homeostasis and repair of the brain. Apart from being highly specialized brain phagocytes, microglia modulate the development and functions of neurons and glial cells through both direct and indirect interactions. Thus, recognizing the elements that influence the homeostasis and heterogeneity of microglia in normal brain development is crucial to understanding the mechanisms that lead to early disease pathogenesis of neurodevelopmental disorders. In this Review, we discuss recent studies that have elucidated the physiological development of microglia and summarize our knowledge of their non-innate immune functions in brain development and tissue repair.
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Affiliation(s)
- Lindsey C Mehl
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | | | - Ouzéna Bouadi
- Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany
| | - Erin M Gibson
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA
| | - Tuan L Tay
- Faculty of Biology, University of Freiburg, Freiburg, 79104, Germany.,BrainLinks-BrainTools Centre, University of Freiburg, Freiburg, 79110, Germany.,Freiburg Institute of Advanced Studies, University of Freiburg, Freiburg, 79104, Germany
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11
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Yang K, Liu T, Wang Z, Liu J, Shen Y, Pan X, Wen R, Xie H, Ruan Z, Tan Z, Chen Y, Guo A, Liu H, Han H, Di Z, Zhang K. Classifying Drosophila Olfactory Projection Neuron Boutons by Quantitative Analysis of Electron Microscopic Reconstruction. iScience 2022; 25:104180. [PMID: 35494235 PMCID: PMC9038572 DOI: 10.1016/j.isci.2022.104180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 01/25/2022] [Accepted: 03/29/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Kai Yang
- School of Basic Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China
- BNU-BUCM Hengqin Innovation Institute of Science and Technology, Zhuhai, Guangdong 518057, China
| | - Tong Liu
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Ze Wang
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Jing Liu
- Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuxinyao Shen
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Xinyi Pan
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Ruyi Wen
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Haotian Xie
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Zhaoxuan Ruan
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Zixiao Tan
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Yingying Chen
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Aike Guo
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
- Huitong College, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - He Liu
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Hua Han
- Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
| | - Zengru Di
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
| | - Ke Zhang
- International Academic Center of Complex Systems, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, Guangdong 519087, China
- Corresponding author
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12
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Boulanger A, Dura JM. Neuron-glia crosstalk in neuronal remodeling and degeneration: Neuronal signals inducing glial cell phagocytic transformation in Drosophila. Bioessays 2022; 44:e2100254. [PMID: 35315125 DOI: 10.1002/bies.202100254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 11/09/2022]
Abstract
Neuronal remodeling is a conserved mechanism that eliminates unwanted neurites and can include the loss of cell bodies. In these processes, a key role for glial cells in events from synaptic pruning to neuron elimination has been clearly identified in the last decades. Signals sent from dying neurons or neurites to be removed are received by appropriate glial cells. After receiving these signals, glial cells infiltrate degenerating sites and then, engulf and clear neuronal debris through phagocytic mechanisms. There are few identified or proposed signals and receptors involved in neuron-glia crosstalk, which induces the transformation of glial cells to phagocytes during neuronal remodeling in Drosophila. Many of these signaling pathways are conserved in mammals. Here, we particularly emphasize the role of Orion, a recently identified neuronal CX3 C chemokine-like secreted protein, which induces astrocyte infiltration and engulfment during mushroom body neuronal remodeling. Although, chemokine signaling was not described previously in insects we propose that chemokine-like involvement in neuron/glial cell interaction is an evolutionarily ancient mechanism.
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Affiliation(s)
- Ana Boulanger
- IGH, Université de Montpellier, CNRS, Montpellier, France
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13
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Nazareth L, St John J, Murtaza M, Ekberg J. Phagocytosis by Peripheral Glia: Importance for Nervous System Functions and Implications in Injury and Disease. Front Cell Dev Biol 2021; 9:660259. [PMID: 33898462 PMCID: PMC8060502 DOI: 10.3389/fcell.2021.660259] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/17/2021] [Indexed: 12/30/2022] Open
Abstract
The central nervous system (CNS) has very limited capacity to regenerate after traumatic injury or disease. In contrast, the peripheral nervous system (PNS) has far greater capacity for regeneration. This difference can be partly attributed to variances in glial-mediated functions, such as axon guidance, structural support, secretion of growth factors and phagocytic activity. Due to their growth-promoting characteristic, transplantation of PNS glia has been trialed for neural repair. After peripheral nerve injuries, Schwann cells (SCs, the main PNS glia) phagocytose myelin debris and attract macrophages to the injury site to aid in debris clearance. One peripheral nerve, the olfactory nerve, is unique in that it continuously regenerates throughout life. The olfactory nerve glia, olfactory ensheathing cells (OECs), are the primary phagocytes within this nerve, continuously clearing axonal debris arising from the normal regeneration of the nerve and after injury. In contrast to SCs, OECs do not appear to attract macrophages. SCs and OECs also respond to and phagocytose bacteria, a function likely critical for tackling microbial invasion of the CNS via peripheral nerves. However, phagocytosis is not always effective; inflammation, aging and/or genetic factors may contribute to compromised phagocytic activity. Here, we highlight the diverse roles of SCs and OECs with the focus on their phagocytic activity under physiological and pathological conditions. We also explore why understanding the contribution of peripheral glia phagocytosis may provide us with translational strategies for achieving axonal regeneration of the injured nervous system and potentially for the treatment of certain neurological diseases.
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Affiliation(s)
- Lynn Nazareth
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - James St John
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Mariyam Murtaza
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Jenny Ekberg
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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14
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Fujita Y, Yamashita T. Mechanisms and significance of microglia-axon interactions in physiological and pathophysiological conditions. Cell Mol Life Sci 2021; 78:3907-3919. [PMID: 33507328 PMCID: PMC11072252 DOI: 10.1007/s00018-021-03758-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/28/2020] [Accepted: 01/06/2021] [Indexed: 12/15/2022]
Abstract
Microglia are the resident immune cells of the central nervous system, and are important for cellular processes. In addition to their classical roles in pathophysiological conditions, these immune cells also dynamically interact with neurons and influence their structure and function in physiological conditions. Microglia have been shown to contact neurons at various points, including the dendrites, cell bodies, synapses, and axons, and support various developmental functions, such as neuronal survival, axon elongation, and maturation of the synaptic circuit. This review summarizes the current knowledge regarding the roles of microglia in brain development, with particular emphasis on microglia-axon interactions. We will review recent findings regarding the functions and signaling pathways involved in the reciprocal interactions between microglia and neurons. Moreover, as these interactions are altered in disease and injury conditions, we also discuss the effect and alteration of microglia-axon interactions in disease progression and the potential role of microglia in developmental brain disorders.
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Affiliation(s)
- Yuki Fujita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
- WPI Immunology Frontier Research Center, Osaka University, 3-1, Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
- WPI Immunology Frontier Research Center, Osaka University, 3-1, Yamadaoka, Suita, Osaka, 565-0871, Japan.
- Graduate School of Frontier Bioscience, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
- Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
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15
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Axonal chemokine-like Orion induces astrocyte infiltration and engulfment during mushroom body neuronal remodeling. Nat Commun 2021; 12:1849. [PMID: 33758182 PMCID: PMC7988174 DOI: 10.1038/s41467-021-22054-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 02/25/2021] [Indexed: 11/13/2022] Open
Abstract
The remodeling of neurons is a conserved fundamental mechanism underlying nervous system maturation and function. Astrocytes can clear neuronal debris and they have an active role in neuronal remodeling. Developmental axon pruning of Drosophila memory center neurons occurs via a degenerative process mediated by infiltrating astrocytes. However, how astrocytes are recruited to the axons during brain development is unclear. Using an unbiased screen, we identify the gene requirement of orion, encoding for a chemokine-like protein, in the developing mushroom bodies. Functional analysis shows that Orion is necessary for both axonal pruning and removal of axonal debris. Orion performs its functions extracellularly and bears some features common to chemokines, a family of chemoattractant cytokines. We propose that Orion is a neuronal signal that elicits astrocyte infiltration and astrocyte-driven axonal engulfment required during neuronal remodeling in the Drosophila developing brain. Astrocytes can engulf axonal debris in the developing brain. However, the mechanisms regulating astrocyte recruitment to the proper axons is unclear. Here, the authors identify Orion as a signal for astrocyte infiltration and engulfment to the mushroom bodies in the Drosophila developing brain.
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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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Kuchenbrod MT, Schubert US, Heintzmann R, Hoeppener S. Revisiting staining of biological samples for electron microscopy: perspectives for recent research. MATERIALS HORIZONS 2021; 8:685-699. [PMID: 34821312 DOI: 10.1039/d0mh01579b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This review revisits essential staining protocols for electron microscopy focussing on the visualization of active sites, i.e. enzymes, metabolites or proteins, in cells and tissues, which have been developed 50 to 60 years ago, however, never were established as standard protocols being used in electron microscopy in a routine fashion. These approaches offer numerous possibilities to expand the knowledge of cellular function and specifically address the localization of active compounds of these systems. It is our conviction, that many of these techniques are still useful, in particular when applied in conjunction with correlative light and electron microscopy. Revisiting specialized classical electron microscopy staining protocols for use in correlative microscopy is particularly promising, as some of these protocols were originally developed as staining methods for light microscopy. To account for this history, rather than summarizing the most recent achievements in literature, we instead first provide an overview of techniques that have been used in the past. While some of these techniques have been successfully implemented into modern microscopy techniques during recent years already, more possibilities are yet to be re-discovered and provide exciting new perspectives for their future use.
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Affiliation(s)
- Maren T Kuchenbrod
- Laboratory of Organic and Macromolecular Chemistry (IOMC) Friedrich Schiller University Jena, Humboldstr. 10, 07743, Germany.
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18
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Vita DJ, Meier CJ, Broadie K. Neuronal fragile X mental retardation protein activates glial insulin receptor mediated PDF-Tri neuron developmental clearance. Nat Commun 2021; 12:1160. [PMID: 33608547 PMCID: PMC7896095 DOI: 10.1038/s41467-021-21429-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/08/2021] [Indexed: 01/31/2023] Open
Abstract
Glia engulf and phagocytose neurons during neural circuit developmental remodeling. Disrupting this pruning process contributes to Fragile X syndrome (FXS), a leading cause of intellectual disability and autism spectrum disorder in mammals. Utilizing a Drosophila FXS model central brain circuit, we identify two glial classes responsible for Draper-dependent elimination of developmentally transient PDF-Tri neurons. We find that neuronal Fragile X Mental Retardation Protein (FMRP) drives insulin receptor activation in glia, promotes glial Draper engulfment receptor expression, and negatively regulates membrane-molding ESCRT-III Shrub function during PDF-Tri neuron clearance during neurodevelopment in Drosophila. In this context, we demonstrate genetic interactions between FMRP and insulin receptor signaling, FMRP and Draper, and FMRP and Shrub in PDF-Tri neuron elimination. We show that FMRP is required within neurons, not glia, for glial engulfment, indicating FMRP-dependent neuron-to-glia signaling mediates neuronal clearance. We conclude neuronal FMRP drives glial insulin receptor activation to facilitate Draper- and Shrub-dependent neuronal clearance during neurodevelopment in Drosophila.
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Affiliation(s)
- Dominic J Vita
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Cole J Meier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Kennedy Center for Research on Human Development, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA.
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19
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Raiders S, Han T, Scott-Hewitt N, Kucenas S, Lew D, Logan MA, Singhvi A. Engulfed by Glia: Glial Pruning in Development, Function, and Injury across Species. J Neurosci 2021; 41:823-833. [PMID: 33468571 PMCID: PMC7880271 DOI: 10.1523/jneurosci.1660-20.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Phagocytic activity of glial cells is essential for proper nervous system sculpting, maintenance of circuitry, and long-term brain health. Glial engulfment of apoptotic cells and superfluous connections ensures that neuronal connections are appropriately refined, while clearance of damaged projections and neurotoxic proteins in the mature brain protects against inflammatory insults. Comparative work across species and cell types in recent years highlights the striking conservation of pathways that govern glial engulfment. Many signaling cascades used during developmental pruning are re-employed in the mature brain to "fine tune" synaptic architecture and even clear neuronal debris following traumatic events. Moreover, the neuron-glia signaling events required to trigger and perform phagocytic responses are impressively conserved between invertebrates and vertebrates. This review offers a compare-and-contrast portrayal of recent findings that underscore the value of investigating glial engulfment mechanisms in a wide range of species and contexts.
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Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
| | - Taeho Han
- UCSF Weill Institute for Neurosciences, University of California San Francisco, San Francisco, California 94158
| | - Nicole Scott-Hewitt
- F.M. Kirby Center for Neurobiology, Boston Children's Hospital, Boston, Massachusetts 02115
- Stanley Center for Psychiatric Research, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Deborah Lew
- Department of Biological Sciences, Fordham University, Bronx, New York 10458
| | - Mary A Logan
- Jungers Center, Department of Neurology, Oregon Health and Science University, Portland, Oregon 97239
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
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20
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Furusawa K, Emoto K. Spatiotemporal regulation of developmental neurite pruning: Molecular and cellular insights from Drosophila models. Neurosci Res 2020; 167:54-63. [PMID: 33309868 DOI: 10.1016/j.neures.2020.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/10/2020] [Accepted: 11/10/2020] [Indexed: 02/02/2023]
Abstract
Developmental neurite pruning is a process by which neurons selectively eliminate unnecessary processes of axons and/or dendrites without cell death, which shapes the mature wiring of nervous systems. In this sense, developmental neurite pruning requires spatiotemporally precise control of local degradation of cellular components including cytoskeletons and membranes. The Drosophila nervous system undergoes large-scale remodeling, including axon/dendrite pruning, during metamorphosis. In addition to this unique phenomenon in the nervous system, powerful genetic tools make the Drosophila nervous system a sophisticated model to investigate spatiotemporal regulation of neural remodeling. This article reviews recent advances to our understanding of the molecular and cellular mechanisms of developmental axon/dendrite pruning, mainly focusing on studies in Drosophila sensory neurons and mushroom body neurons.
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Affiliation(s)
- Kotaro Furusawa
- Department of Biological Sciences, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Kazuo Emoto
- Department of Biological Sciences, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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21
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Li Q, Haney MS. The role of glia in protein aggregation. Neurobiol Dis 2020; 143:105015. [PMID: 32663608 DOI: 10.1016/j.nbd.2020.105015] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 06/01/2020] [Accepted: 07/07/2020] [Indexed: 01/20/2023] Open
Abstract
Protein aggregation diseases involve intracellular accumulation or extracellular deposition of certain protein species in neuronal or glial cells, leading to neurodegeneration and shortened lifespan. Prime examples include Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD), which are affected by overlapping or specific aggregation-prone proteins. Mounting evidence suggests that dysfunctional glial cells may be major drivers for some diseases, and when they are not causal factors, they could still significantly exacerbate or alleviate disease progression by playing a plethora of detrimental or beneficial roles. Here we review the diverse functions performed by glial cells in a variety of protein aggregation diseases, highlighting the complexity of the issue and the interconnected relationships between these multifaceted effects.
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Affiliation(s)
- Qingyun Li
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Michael S Haney
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.
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22
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Kim T, Song B, Lee IS. Drosophila Glia: Models for Human Neurodevelopmental and Neurodegenerative Disorders. Int J Mol Sci 2020; 21:E4859. [PMID: 32660023 PMCID: PMC7402321 DOI: 10.3390/ijms21144859] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/27/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are key players in the proper formation and maintenance of the nervous system, thus contributing to neuronal health and disease in humans. However, little is known about the molecular pathways that govern glia-neuron communications in the diseased brain. Drosophila provides a useful in vivo model to explore the conserved molecular details of glial cell biology and their contributions to brain function and disease susceptibility. Herein, we review recent studies that explore glial functions in normal neuronal development, along with Drosophila models that seek to identify the pathological implications of glial defects in the context of various central nervous system disorders.
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Affiliation(s)
| | | | - Im-Soon Lee
- Department of Biological Sciences, Center for CHANS, Konkuk University, Seoul 05029, Korea; (T.K.); (B.S.)
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23
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Schmied A, Soda T, Gerig G, Styner M, Swanson MR, Elison JT, Shen MD, McKinstry RC, Pruett JR, Botteron KN, Estes AM, Dager SR, Hazlett HC, Schultz RT, Piven J, Wolff JJ. Sex differences associated with corpus callosum development in human infants: A longitudinal multimodal imaging study. Neuroimage 2020; 215:116821. [PMID: 32276067 DOI: 10.1016/j.neuroimage.2020.116821] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/21/2020] [Accepted: 03/27/2020] [Indexed: 02/02/2023] Open
Abstract
The corpus callosum (CC) is the largest connective pathway in the human brain, linking cerebral hemispheres. There is longstanding debate in the scientific literature whether sex differences are evident in this structure, with many studies indicating the structure is larger in females. However, there are few data pertaining to this issue in infancy, during which time the most rapid developmental changes to the CC occur. In this study, we examined longitudinal brain imaging data collected from 104 infants at ages 6, 12, and 24 months. We identified sex differences in brain-size adjusted CC area and thickness characterized by a steeper rate of growth in males versus females from ages 6-24 months. In contrast to studies of older children and adults, CC size was larger for male compared to female infants. Based on diffusion tensor imaging data, we found that CC thickness is significantly associated with underlying microstructural organization. However, we observed no sex differences in the association between microstructure and thickness, suggesting that the role of factors such as axon density and/or myelination in determining CC size is generally equivalent between sexes. Finally, we found that CC length was negatively associated with nonverbal ability among females.
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Affiliation(s)
- Astrid Schmied
- Department of Educational Psychology, University of Minnesota, Minneapolis, MN, USA
| | - Takahiro Soda
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Guido Gerig
- Department of Computer Science & Engineering, New York University, New York City, NY, USA
| | - Martin Styner
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Meghan R Swanson
- School of Behavioral & Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
| | - Jed T Elison
- Institute of Child Development, University of Minnesota, Minneapolis, MN, USA
| | - Mark D Shen
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Robert C McKinstry
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - John R Pruett
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Kelly N Botteron
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Annette M Estes
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA, USA
| | - Stephen R Dager
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Heather C Hazlett
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Robert T Schultz
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph Piven
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Jason J Wolff
- Department of Educational Psychology, University of Minnesota, Minneapolis, MN, USA.
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24
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With a little help from my friends: how intercellular communication shapes neuronal remodeling. Curr Opin Neurobiol 2020; 63:23-30. [PMID: 32092689 DOI: 10.1016/j.conb.2020.01.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 01/28/2020] [Indexed: 11/22/2022]
Abstract
Developmental neuronal remodeling shapes the mature connectivity of the nervous system in both vertebrates and invertebrates. Remodeling often combines degenerative and regenerative events, and defects in its normal progression have been linked to neurological disorders. Here we review recent progress that highlights the roles of cell-cell interactions during remodeling. We propose that these are fundamental to elucidating how spatiotemporal control of remodeling and coordinated circuit remodeling are achieved. We cover examples spanning various neuronal circuits in vertebrates and invertebrates and involving interactions between neurons and different cell types.
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25
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Hilu-Dadia R, Kurant E. Glial phagocytosis in developing and mature Drosophila CNS: tight regulation for a healthy brain. Curr Opin Immunol 2020; 62:62-68. [DOI: 10.1016/j.coi.2019.11.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/25/2019] [Indexed: 12/23/2022]
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26
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Li J, Han S, Li H, Udeshi ND, Svinkina T, Mani DR, Xu C, Guajardo R, Xie Q, Li T, Luginbuhl DJ, Wu B, McLaughlin CN, Xie A, Kaewsapsak P, Quake SR, Carr SA, Ting AY, Luo L. Cell-Surface Proteomic Profiling in the Fly Brain Uncovers Wiring Regulators. Cell 2020; 180:373-386.e15. [PMID: 31955847 DOI: 10.1016/j.cell.2019.12.029] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 01/12/2023]
Abstract
Molecular interactions at the cellular interface mediate organized assembly of single cells into tissues and, thus, govern the development and physiology of multicellular organisms. Here, we developed a cell-type-specific, spatiotemporally resolved approach to profile cell-surface proteomes in intact tissues. Quantitative profiling of cell-surface proteomes of Drosophila olfactory projection neurons (PNs) in pupae and adults revealed global downregulation of wiring molecules and upregulation of synaptic molecules in the transition from developing to mature PNs. A proteome-instructed in vivo screen identified 20 cell-surface molecules regulating neural circuit assembly, many of which belong to evolutionarily conserved protein families not previously linked to neural development. Genetic analysis further revealed that the lipoprotein receptor LRP1 cell-autonomously controls PN dendrite targeting, contributing to the formation of a precise olfactory map. These findings highlight the power of temporally resolved in situ cell-surface proteomic profiling in discovering regulators of brain wiring.
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Affiliation(s)
- Jiefu Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
| | - Shuo Han
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Hongjie Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Namrata D Udeshi
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Tanya Svinkina
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - D R Mani
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chuanyun Xu
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ricardo Guajardo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Qijing Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Tongchao Li
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - David J Luginbuhl
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Bing Wu
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Colleen N McLaughlin
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Anthony Xie
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Pornchai Kaewsapsak
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Stephen R Quake
- Departments of Bioengineering and Applied Physics, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Chan Zuckerberg Biohub, Stanford University, Stanford, CA 94305, USA.
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
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27
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Abstract
The field of microfluidics allows for the precise spatial manipulation of small amounts of fluids. Within microstructures, laminar flow of fluids can be exploited to control the diffusion of small molecules, creating desired microenvironments for cells. Cellular neuroscience has benefited greatly from devices designed to fluidically isolate cell bodies and axons. Microfluidic devices specialized for neuron compartmentalization are made of polydimethylsiloxane (PDMS) which is gas permeable, is compatible with fluorescence microscopy, and has low cost. These devices are commonly used to study signals initiated exclusively on axons, somatodendritic compartments, or even single synapses. We have also found that microfluidic devices allow for rapid, reproducible interrogation of axon degeneration. Here, we describe the methodology for assessing axonal degeneration in microfluidic devices. We describe several use cases, including enucleation (removal of cell bodies) and trophic deprivation to investigate axon degeneration in pathological and developmental scenarios, respectively.
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Affiliation(s)
- Yu Yong
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Christopher Hughes
- Department of Physics and Astronomy, James Madison University, Harrisonburg, VA, USA
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28
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Portela M, Venkataramani V, Fahey-Lozano N, Seco E, Losada-Perez M, Winkler F, Casas-Tintó S. Glioblastoma cells vampirize WNT from neurons and trigger a JNK/MMP signaling loop that enhances glioblastoma progression and neurodegeneration. PLoS Biol 2019; 17:e3000545. [PMID: 31846454 PMCID: PMC6917273 DOI: 10.1371/journal.pbio.3000545] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022] Open
Abstract
Glioblastoma (GB) is the most lethal brain tumor, and Wingless (Wg)-related integration site (WNT) pathway activation in these tumors is associated with a poor prognosis. Clinically, the disease is characterized by progressive neurological deficits. However, whether these symptoms result from direct or indirect damage to neurons is still unresolved. Using Drosophila and primary xenografts as models of human GB, we describe, here, a mechanism that leads to activation of WNT signaling (Wg in Drosophila) in tumor cells. GB cells display a network of tumor microtubes (TMs) that enwrap neurons, accumulate Wg receptor Frizzled1 (Fz1), and, thereby, deplete Wg from neurons, causing neurodegeneration. We have defined this process as “vampirization.” Furthermore, GB cells establish a positive feedback loop to promote their expansion, in which the Wg pathway activates cJun N-terminal kinase (JNK) in GB cells, and, in turn, JNK signaling leads to the post-transcriptional up-regulation and accumulation of matrix metalloproteinases (MMPs), which facilitate TMs’ infiltration throughout the brain, TMs’ network expansion, and further Wg depletion from neurons. Consequently, GB cells proliferate because of the activation of the Wg signaling target, β-catenin, and neurons degenerate because of Wg signaling extinction. Our findings reveal a molecular mechanism for TM production, infiltration, and maintenance that can explain both neuron-dependent tumor progression and also the neural decay associated with GB. Glioblastoma is the most lethal brain tumor and is characterized by progressive neurological deficits. However, whether these symptoms result from direct or indirect damage to neurons is still unresolved. This study shows that glioblastoma cells compete with healthy neurons for survival, depleting the signaling molecule Wg and causing neurodegeneration.
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Affiliation(s)
- Marta Portela
- Instituto Cajal-CSIC, Madrid, Spain
- * E-mail: (SCT); (MP)
| | - Varun Venkataramani
- Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany
- Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | | | | | | | - Frank Winkler
- Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany
- Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
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29
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Hakim-Mishnaevski K, Flint-Brodsly N, Shklyar B, Levy-Adam F, Kurant E. Glial Phagocytic Receptors Promote Neuronal Loss in Adult Drosophila Brain. Cell Rep 2019; 29:1438-1448.e3. [DOI: 10.1016/j.celrep.2019.09.086] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 07/30/2019] [Accepted: 09/27/2019] [Indexed: 12/22/2022] Open
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30
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Abstract
Maturation of neuronal circuits requires selective elimination of synaptic connections. Although neuron-intrinsic mechanisms are important in this process, it is increasingly recognized that glial cells also play a critical role. Without proper functioning of these cells, the number, morphology, and function of synaptic contacts are profoundly altered, resulting in abnormal connectivity and behavioral abnormalities. In addition to their role in synaptic refinement, glial cells have also been implicated in pathological synapse loss and dysfunction following injury or nervous system degeneration in adults. Although mechanisms regulating glia-mediated synaptic elimination are still being uncovered, it is clear this complex process involves many cues that promote and inhibit the removal of specific synaptic connections. Gaining a greater understanding of these signals and the contribution of different cell types will not only provide insight into this critical biological event but also be instrumental in advancing knowledge of brain development and neural disease.
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Affiliation(s)
- Daniel K. Wilton
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Lasse Dissing-Olesen
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Beth Stevens
- Department of Neurology and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Stanley Center, Broad Institute, Cambridge, Massachusetts 02142, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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31
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Razetti A, Medioni C, Malandain G, Besse F, Descombes X. A stochastic framework to model axon interactions within growing neuronal populations. PLoS Comput Biol 2018; 14:e1006627. [PMID: 30507939 PMCID: PMC6292646 DOI: 10.1371/journal.pcbi.1006627] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 12/13/2018] [Accepted: 11/09/2018] [Indexed: 12/16/2022] Open
Abstract
The confined and crowded environment of developing brains imposes spatial constraints on neuronal cells that have evolved individual and collective strategies to optimize their growth. These include organizing neurons into populations extending their axons to common target territories. How individual axons interact with each other within such populations to optimize innervation is currently unclear and difficult to analyze experimentally in vivo. Here, we developed a stochastic model of 3D axon growth that takes into account spatial environmental constraints, physical interactions between neighboring axons, and branch formation. This general, predictive and robust model, when fed with parameters estimated on real neurons from the Drosophila brain, enabled the study of the mechanistic principles underlying the growth of axonal populations. First, it provided a novel explanation for the diversity of growth and branching patterns observed in vivo within populations of genetically identical neurons. Second, it uncovered that axon branching could be a strategy optimizing the overall growth of axons competing with others in contexts of high axonal density. The flexibility of this framework will make it possible to investigate the rules underlying axon growth and regeneration in the context of various neuronal populations. Understanding how neuronal cells establish complex circuits with specific functions within a developing brain is a major current challenge. Over the last past years, enormous progress has been done to precisely resolve brain anatomy and to dissect the mechanisms controlling the establishment of precise neuronal networks. However, due to the extreme complexity of the brain, it is still experimentally difficult to investigate in vivo how neurons interact with each other and with their physical environments to innervate target territories during development. Here, we have developed a framework that integrates a dynamic 3D mathematical model of single axonal growth with parameters estimated from neurons grown in vivo and simulations of entire populations of growing axons. The emergent properties of our model enable the study of the mechanistic principles underlying the growth of axonal population in developing brains. Specifically, our results highlight the impact of mechanical interactions on both individual and collective axon growth, and uncover how branching regulate this process.
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32
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Yildirim K, Petri J, Kottmeier R, Klämbt C. Drosophila glia: Few cell types and many conserved functions. Glia 2018; 67:5-26. [DOI: 10.1002/glia.23459] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/25/2018] [Accepted: 05/04/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Kerem Yildirim
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Johanna Petri
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Rita Kottmeier
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
| | - Christian Klämbt
- Institute for Neuro and Behavioral Biology; University of Münster; Badestraße 9, 48149 Münster Germany
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33
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Savage JC, Picard K, González-Ibáñez F, Tremblay MÈ. A Brief History of Microglial Ultrastructure: Distinctive Features, Phenotypes, and Functions Discovered Over the Past 60 Years by Electron Microscopy. Front Immunol 2018; 9:803. [PMID: 29922276 PMCID: PMC5996933 DOI: 10.3389/fimmu.2018.00803] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/03/2018] [Indexed: 01/01/2023] Open
Abstract
The first electron microscope was constructed in 1931. Several decades later, techniques were developed to allow the first ultrastructural analysis of microglia by transmission electron microscopy (EM). In the 50 years that followed, important roles of microglia have been identified, specifically due to the ultrastructural resolution currently available only with EM. In particular, the addition of electron-dense staining using immunohistochemical EM methods has allowed the identification of microglial cell bodies, as well as processes, which are difficult to recognize in EM, and to uncover their complex interactions with neurons and synapses. The ability to recognize neuronal, astrocytic, and oligodendrocytic compartments in the neuropil without any staining is another invaluable advantage of EM over light microscopy for studying intimate cell-cell contacts. The technique has been essential in defining microglial interactions with neurons and synapses, thus providing, among other discoveries, important insights into their roles in synaptic stripping and pruning via phagocytosis of extraneous synapses. Recent technological advances in EM including serial block-face imaging and focused-ion beam scanning EM have also facilitated automated acquisition of large tissue volumes required to reconstruct neuronal circuits in 3D at nanometer-resolution. These cutting-edge techniques which are now becoming increasingly available will further revolutionize the study of microglia across stages of the lifespan, brain regions, and contexts of health and disease. In this mini-review, we will focus on defining the distinctive ultrastructural features of microglia and the unique insights into their function that were provided by EM.
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Affiliation(s)
- Julie C. Savage
- Axe neurosciences, Centre de Recherche du CHU de Québec – Université Laval, Québec City, QC, Canada
- Département de médecine moléculaire, Université Laval, Québec City, QC, Canada
| | - Katherine Picard
- Axe neurosciences, Centre de Recherche du CHU de Québec – Université Laval, Québec City, QC, Canada
- Département de médecine moléculaire, Université Laval, Québec City, QC, Canada
| | - Fernando González-Ibáñez
- Axe neurosciences, Centre de Recherche du CHU de Québec – Université Laval, Québec City, QC, Canada
- Département de médecine moléculaire, Université Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Axe neurosciences, Centre de Recherche du CHU de Québec – Université Laval, Québec City, QC, Canada
- Département de médecine moléculaire, Université Laval, Québec City, QC, Canada
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34
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Li H, Shuster SA, Li J, Luo L. Linking neuronal lineage and wiring specificity. Neural Dev 2018; 13:5. [PMID: 29653548 PMCID: PMC5899351 DOI: 10.1186/s13064-018-0102-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/14/2018] [Indexed: 02/01/2023] Open
Abstract
Brain function requires precise neural circuit assembly during development. Establishing a functional circuit involves multiple coordinated steps ranging from neural cell fate specification to proper matching between pre- and post-synaptic partners. How neuronal lineage and birth timing influence wiring specificity remains an open question. Recent findings suggest that the relationships between lineage, birth timing, and wiring specificity vary in different neuronal circuits. In this review, we summarize our current understanding of the cellular, molecular, and developmental mechanisms linking neuronal lineage and birth timing to wiring specificity in a few specific systems in Drosophila and mice, and review different methods employed to explore these mechanisms.
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Affiliation(s)
- Hongjie Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - S. Andrew Shuster
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305 USA
| | - Jiefu Li
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Liqun Luo
- Department of Biology and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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35
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Tay TL, Béchade C, D'Andrea I, St-Pierre MK, Henry MS, Roumier A, Tremblay ME. Microglia Gone Rogue: Impacts on Psychiatric Disorders across the Lifespan. Front Mol Neurosci 2018; 10:421. [PMID: 29354029 PMCID: PMC5758507 DOI: 10.3389/fnmol.2017.00421] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/04/2017] [Indexed: 12/21/2022] Open
Abstract
Microglia are the predominant immune response cells and professional phagocytes of the central nervous system (CNS) that have been shown to be important for brain development and homeostasis. These cells present a broad spectrum of phenotypes across stages of the lifespan and especially in CNS diseases. Their prevalence in all neurological pathologies makes it pertinent to reexamine their distinct roles during steady-state and disease conditions. A major question in the field is determining whether the clustering and phenotypical transformation of microglial cells are leading causes of pathogenesis, or potentially neuroprotective responses to the onset of disease. The recent explosive growth in our understanding of the origin and homeostasis of microglia, uncovering their roles in shaping of the neural circuitry and synaptic plasticity, allows us to discuss their emerging functions in the contexts of cognitive control and psychiatric disorders. The distinct mesodermal origin and genetic signature of microglia in contrast to other neuroglial cells also make them an interesting target for the development of therapeutics. Here, we review the physiological roles of microglia, their contribution to the effects of environmental risk factors (e.g., maternal infection, early-life stress, dietary imbalance), and their impact on psychiatric disorders initiated during development (e.g., Nasu-Hakola disease (NHD), hereditary diffuse leukoencephaly with spheroids, Rett syndrome, autism spectrum disorders (ASDs), and obsessive-compulsive disorder (OCD)) or adulthood (e.g., alcohol and drug abuse, major depressive disorder (MDD), bipolar disorder (BD), schizophrenia, eating disorders and sleep disorders). Furthermore, we discuss the changes in microglial functions in the context of cognitive aging, and review their implication in neurodegenerative diseases of the aged adult (e.g., Alzheimer’s and Parkinson’s). Taking into account the recent identification of microglia-specific markers, and the availability of compounds that target these cells selectively in vivo, we consider the prospect of disease intervention via the microglial route.
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Affiliation(s)
- Tuan Leng Tay
- Institute of Neuropathology, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Catherine Béchade
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Ivana D'Andrea
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | | | - Mathilde S Henry
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Anne Roumier
- INSERM UMR-S 839, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Marie-Eve Tremblay
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada.,Département de Médecine Moléculaire, Université Laval, Québec, QC, Canada
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36
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Common and Divergent Mechanisms in Developmental Neuronal Remodeling and Dying Back Neurodegeneration. Curr Biol 2017; 26:R628-R639. [PMID: 27404258 DOI: 10.1016/j.cub.2016.05.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cell death is an inherent process that is required for the proper wiring of the nervous system. Studies over the last four decades have shown that, in a parallel developmental pathway, axons and dendrites are eliminated without the death of the neuron. This developmentally regulated 'axonal death' results in neuronal remodeling, which is an essential mechanism to sculpt neuronal networks in both vertebrates and invertebrates. Studies across various organisms have demonstrated that a conserved strategy in the formation of adult neuronal circuitry often involves generating too many connections, most of which are later eliminated with high temporal and spatial resolution. Can neuronal remodeling be regarded as developmentally and spatially regulated neurodegeneration? It has been previously speculated that injury-induced degeneration (Wallerian degeneration) shares some molecular features with 'dying back' neurodegenerative diseases. In this opinion piece, we examine the similarities and differences between the mechanisms regulating neuronal remodeling and those being perturbed in dying back neurodegenerative diseases. We focus primarily on amyotrophic lateral sclerosis and peripheral neuropathies and highlight possible shared pathways and mechanisms. While mechanistic data are only just beginning to emerge, and despite the inherent differences between disease-oriented and developmental processes, we believe that some of the similarities between these developmental and disease-initiated degeneration processes warrant closer collaborations and crosstalk between these different fields.
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37
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Richier B, Vijandi CDM, Mackensen S, Salecker I. Lapsyn controls branch extension and positioning of astrocyte-like glia in the Drosophila optic lobe. Nat Commun 2017; 8:317. [PMID: 28827667 PMCID: PMC5567088 DOI: 10.1038/s41467-017-00384-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 06/21/2017] [Indexed: 11/09/2022] Open
Abstract
Astrocytes have diverse, remarkably complex shapes in different brain regions. Their branches closely associate with neurons. Despite the importance of this heterogeneous glial cell type for brain development and function, the molecular cues controlling astrocyte branch morphogenesis and positioning during neural circuit assembly remain largely unknown. We found that in the Drosophila visual system, astrocyte-like medulla neuropil glia (mng) variants acquire stereotypic morphologies with columnar and layered branching patterns in a stepwise fashion from mid-metamorphosis onwards. Using knockdown and loss-of-function analyses, we uncovered a previously unrecognized role for the transmembrane leucine-rich repeat protein Lapsyn in regulating mng development. lapsyn is expressed in mng and cell-autonomously required for branch extension into the synaptic neuropil and anchoring of cell bodies at the neuropil border. Lapsyn works in concert with the fibroblast growth factor (FGF) pathway to promote branch morphogenesis, while correct positioning is essential for mng survival mediated by gliotrophic FGF signaling. How glial cells, such as astrocytes, acquire their characteristic morphology during development is poorly understood. Here the authors describe the morphogenesis of astrocyte-like glia in the Drosophila optic lobe, and through a RNAi screen, they identify a transmembrane LRR protein–Lapsyn–that plays a critical role in this process.
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Affiliation(s)
- Benjamin Richier
- The Francis Crick Institute, Visual Circuit Assembly Laboratory, 1 Midland Road, London, NW1 1AT, UK.,The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | | | - Stefanie Mackensen
- The Francis Crick Institute, Visual Circuit Assembly Laboratory, 1 Midland Road, London, NW1 1AT, UK.,University of Münster, Institute of Neuro- and Behavioral Biology, Badestr. 9, 48149, Muenster, Germany
| | - Iris Salecker
- The Francis Crick Institute, Visual Circuit Assembly Laboratory, 1 Midland Road, London, NW1 1AT, UK.
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38
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Lim JJ, Grinstein S, Roth Z. Diversity and Versatility of Phagocytosis: Roles in Innate Immunity, Tissue Remodeling, and Homeostasis. Front Cell Infect Microbiol 2017; 7:191. [PMID: 28589095 PMCID: PMC5440456 DOI: 10.3389/fcimb.2017.00191] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 05/03/2017] [Indexed: 12/23/2022] Open
Abstract
Phagocytosis, a critical early event in the microbicidal response of neutrophils, is now appreciated to serve multiple functions in a variety of cell types. Professional phagocytes play a central role in innate immunity by eliminating pathogenic bacteria, fungi and malignant cells, and contribute to adaptive immunity by presenting antigens to lymphocytes. In addition, phagocytes play a part in tissue remodeling and maintain overall homeostasis by disposing of apoptotic cells, a task shared by non-professional phagocytes, often of epithelial origin. This functional versatility is supported by a vast array of receptors capable of recognizing a striking variety of foreign and endogenous ligands. Here we present an abbreviated overview of the different types of phagocytes, their varied modes of signaling and particle engulfment, and the multiple physiological roles of phagocytosis.
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Affiliation(s)
- Justin J Lim
- Program in Cell Biology, Hospital for Sick ChildrenToronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick ChildrenToronto, ON, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's HospitalToronto, ON, Canada.,Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Ziv Roth
- Program in Cell Biology, Hospital for Sick ChildrenToronto, ON, Canada
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39
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dMyc is required in retinal progenitors to prevent JNK-mediated retinal glial activation. PLoS Genet 2017; 13:e1006647. [PMID: 28267791 PMCID: PMC5360344 DOI: 10.1371/journal.pgen.1006647] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 03/21/2017] [Accepted: 02/21/2017] [Indexed: 11/25/2022] Open
Abstract
In the nervous system, glial cells provide crucial insulation and trophic support to neurons and are important for neuronal survival. In reaction to a wide variety of insults, glial cells respond with changes in cell morphology and metabolism to allow repair. Additionally, these cells can acquire migratory and proliferative potential. In particular, after axonal damage or pruning the clearance of axonal debris by glial cells is key for a healthy nervous system. Thus, bidirectional neuron-glial interactions are crucial in development, but little is known about the cellular sensors and signalling pathways involved. In here, we show that decreased cellular fitness in retinal progenitors caused by reduced Drosophila Myc expression triggers non cell-autonomous activation of retinal glia proliferation and overmigration. Glia migration occurs beyond its normal limit near the boundary between differentiated photoreceptors and precursor cells, extending into the progenitor domain. This overmigration is stimulated by JNK activation (and the function of its target Mmp1), while proliferative responses are mediated by Dpp/TGF-β signalling activation. For a functional nervous system, neurons transmit information from cell to cell while glial cells provide crucial insulation and trophic support to neurons, which is important for neuronal survival. Glial cells are one of the most plastic cell types being able to adapt and respond to changing environmental stimuli. In this work we inhibit the function of the growth regulator dMyc in Drosophila retinal primordium, the eye imaginal discs. Glial cell numbers and migration pattern to the eye disc are tightly controlled but in dMyc-depleted retinas the glial cells overcome their normal barriers and overmigrate into the eye progenitors domain. We show evidence that this process is mediated by JNK activation in the presence of metalloproteinases. We discuss the biological role of overmigrating glia in tissue regeneration and/or confinement of the damaged area.
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40
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Abstract
Abstract
Axonal loss is an important process both during development and diseases of the nervous system. While the molecular mechanisms that mediate axonal loss are largely elusive, modern imaging technology affords an increasingly clear view of the cellular processes that allow nerve cells to shed individiual axon branches or even dismantle entire parts of their axonal projections. The present review discusses the characteristics of post-traumatic Wallerian degeneration, the process of axonal loss currently best understood. Subsequently, the properties of a number of recently discovered axonal loss phenomena are described. These phenomena explain some of the axonal loss that occurs locally after axon transection, during neuro-inflammatory insults, and as part of normal neurodevelopment.
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41
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Ng J, Browning A, Lechner L, Terada M, Howard G, Jefferis GSXE. Genetically targeted 3D visualisation of Drosophila neurons under Electron Microscopy and X-Ray Microscopy using miniSOG. Sci Rep 2016; 6:38863. [PMID: 27958322 PMCID: PMC5153665 DOI: 10.1038/srep38863] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/11/2016] [Indexed: 11/23/2022] Open
Abstract
Large dimension, high-resolution imaging is important for neural circuit visualisation as neurons have both long- and short-range patterns: from axons and dendrites to the numerous synapses at terminal endings. Electron Microscopy (EM) is the favoured approach for synaptic resolution imaging but how such structures can be segmented from high-density images within large volume datasets remains challenging. Fluorescent probes are widely used to localise synapses, identify cell-types and in tracing studies. The equivalent EM approach would benefit visualising such labelled structures from within sub-cellular, cellular, tissue and neuroanatomical contexts. Here we developed genetically-encoded, electron-dense markers using miniSOG. We demonstrate their ability in 1) labelling cellular sub-compartments of genetically-targeted neurons, 2) generating contrast under different EM modalities, and 3) segmenting labelled structures from EM volumes using computer-assisted strategies. We also tested non-destructive X-ray imaging on whole Drosophila brains to evaluate contrast staining. This enabled us to target specific regions for EM volume acquisition.
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Affiliation(s)
- Julian Ng
- Department of Zoology, Downing Street, Cambridge, CB2 3EJ, United Kingdom.,Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
| | - Alyssa Browning
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Lorenz Lechner
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Masako Terada
- Carl Zeiss X-ray Microscopy Inc., 4385 Hopyard Rd., Suite 100, Pleasanton, CA 94588, USA
| | - Gillian Howard
- Cell Biology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
| | - Gregory S X E Jefferis
- Department of Zoology, Downing Street, Cambridge, CB2 3EJ, United Kingdom.,Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, CB2 0QH, United Kingdom
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42
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Yaniv SP, Schuldiner O. A fly's view of neuronal remodeling. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 5:618-35. [PMID: 27351747 PMCID: PMC5086085 DOI: 10.1002/wdev.241] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 04/10/2016] [Accepted: 04/18/2016] [Indexed: 11/17/2022]
Abstract
Developmental neuronal remodeling is a crucial step in sculpting the final and mature brain connectivity in both vertebrates and invertebrates. Remodeling includes degenerative events, such as neurite pruning, that may be followed by regeneration to form novel connections during normal development. Drosophila provides an excellent model to study both steps of remodeling since its nervous system undergoes massive and stereotypic remodeling during metamorphosis. Although pruning has been widely studied, our knowledge of the molecular and cellular mechanisms is far from complete. Our understanding of the processes underlying regrowth is even more fragmentary. In this review, we discuss recent progress by focusing on three groups of neurons that undergo stereotypic pruning and regrowth during metamorphosis, the mushroom body γ neurons, the dendritic arborization neurons and the crustacean cardioactive peptide peptidergic neurons. By comparing and contrasting the mechanisms involved in remodeling of these three neuronal types, we highlight the common themes and differences as well as raise key questions for future investigation in the field. WIREs Dev Biol 2016, 5:618–635. doi: 10.1002/wdev.241 For further resources related to this article, please visit the WIREs website
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Affiliation(s)
- Shiri P Yaniv
- Dept of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Oren Schuldiner
- Dept of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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43
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Rybak J, Talarico G, Ruiz S, Arnold C, Cantera R, Hansson BS. Synaptic circuitry of identified neurons in the antennal lobe of Drosophila melanogaster. J Comp Neurol 2016; 524:1920-56. [PMID: 26780543 PMCID: PMC6680330 DOI: 10.1002/cne.23966] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/05/2016] [Accepted: 01/13/2016] [Indexed: 11/09/2022]
Abstract
In Drosophila melanogaster olfactory sensory neurons (OSNs) establish synapses with projection neurons (PNs) and local interneurons within antennal lobe (AL) glomeruli. Substantial knowledge regarding this circuitry has been obtained by functional studies, whereas ultrastructural evidence of synaptic contacts is scarce. To fill this gap, we studied serial sections of three glomeruli using electron microscopy. Ectopic expression of a membrane-bound peroxidase allowed us to map synaptic sites along PN dendrites. Our data prove for the first time that each of the three major types of AL neurons is both pre- and postsynaptic to the other two types, as previously indicated by functional studies. PN dendrites carry a large proportion of output synapses, with approximately one output per every three input synapses. Detailed reconstructions of PN dendrites showed that these synapses are distributed unevenly, with input and output sites partially segregated along a proximal-distal gradient and the thinnest branches carrying solely input synapses. Moreover, our data indicate synapse clustering, as we found evidence of dendritic tiling of PN dendrites. PN output synapses exhibited T-shaped presynaptic densities, mostly arranged as tetrads. In contrast, output synapses from putative OSNs showed elongated presynaptic densities in which the T-bar platform was supported by several pedestals and contacted as many as 20 postsynaptic profiles. We also discovered synaptic contacts between the putative OSNs. The average synaptic density in the glomerular neuropil was about two synapses/µm(3) . These results are discussed with regard to current models of olfactory glomerular microcircuits across species.
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Affiliation(s)
- Jürgen Rybak
- Department of Evolutionary NeuroethologyMax Planck Institute for Chemical Ecology07745JenaGermany
| | - Giovanni Talarico
- Department of Evolutionary NeuroethologyMax Planck Institute for Chemical Ecology07745JenaGermany
| | - Santiago Ruiz
- Clemente Estable Institute of Biological Research11600 MontevideoUruguay
| | - Christopher Arnold
- Department of Evolutionary NeuroethologyMax Planck Institute for Chemical Ecology07745JenaGermany
| | - Rafael Cantera
- Clemente Estable Institute of Biological Research11600 MontevideoUruguay
- Zoology DepartmentStockholm University10691StockholmSweden
| | - Bill S. Hansson
- Department of Evolutionary NeuroethologyMax Planck Institute for Chemical Ecology07745JenaGermany
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44
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Xu S, Elefant F. Tip off the HAT- Epigenetic control of learning and memory by Drosophila Tip60. Fly (Austin) 2016; 9:22-8. [PMID: 26327426 DOI: 10.1080/19336934.2015.1080887] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Disruption of epigenetic gene control mechanisms involving histone acetylation in the brain causes cognitive impairment, a debilitating hallmark of most neurodegenerative disorders. Histone acetylation regulates cognitive gene expression via chromatin packaging control in neurons. Unfortunately, the histone acetyltransferases (HATs) that generate such neural epigenetic signatures and their mechanisms of action remain unclear. Our recent findings provide insight into this question by demonstrating that Tip60 HAT action is critical for morphology and function of the mushroom body (MB), the learning and memory center in the Drosophila brain. We show that Tip60 is robustly produced in MB Kenyon cells and extending axonal lobes and that targeted MB Tip60 HAT loss results in axonal outgrowth disruption. Functional consequences of loss and gain of Tip60 HAT levels in the MB are evidenced by defects in memory. Tip60 ChIP-Seq analysis reveals enrichment for genes that function in cognitive processes and accordingly, key genes representing these pathways are misregulated in the Tip60 HAT mutant fly brain. Remarkably, increasing levels of Tip60 in the MB rescues learning and memory deficits resulting from Alzheimer's disease associated amyloid precursor protein (APP) induced neurodegeneration. Our studies highlight the potential of HAT activators as a therapeutic option for cognitive disorders.
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Affiliation(s)
- Songjun Xu
- a Department of Biology ; Drexel University ; Philadelphia , PA USA
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45
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Tay TL, Savage JC, Hui CW, Bisht K, Tremblay MÈ. Microglia across the lifespan: from origin to function in brain development, plasticity and cognition. J Physiol 2016; 595:1929-1945. [PMID: 27104646 DOI: 10.1113/jp272134] [Citation(s) in RCA: 352] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 03/15/2016] [Indexed: 12/11/2022] Open
Abstract
Microglia are the only immune cells that permanently reside in the central nervous system (CNS) alongside neurons and other types of glial cells. The past decade has witnessed a revolution in our understanding of their roles during normal physiological conditions. Cutting-edge techniques revealed that these resident immune cells are critical for proper brain development, actively maintain health in the mature brain, and rapidly adapt their function to physiological or pathophysiological needs. In this review, we highlight recent studies on microglial origin (from the embryonic yolk sac) and the factors regulating their differentiation and homeostasis upon brain invasion. Elegant experiments tracking microglia in the CNS allowed studies of their unique roles compared with other types of resident macrophages. Here we review the emerging roles of microglia in brain development, plasticity and cognition, and discuss the implications of the depletion or dysfunction of microglia for our understanding of disease pathogenesis. Immune activation, inflammation and various other conditions resulting in undesirable microglial activity at different stages of life could severely impair learning, memory and other essential cognitive functions. The diversity of microglial phenotypes across the lifespan, between compartments of the CNS, and sexes, as well as their crosstalk with the body and external environment, is also emphasised. Understanding what defines particular microglial phenotypes is of major importance for future development of innovative therapies controlling their effector functions, with consequences for cognition across chronic stress, ageing, neuropsychiatric and neurological diseases.
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Affiliation(s)
- Tuan Leng Tay
- Institute of Neuropathology, University of Freiburg, Germany
| | - Julie C Savage
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
| | - Chin Wai Hui
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
| | - Kanchan Bisht
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
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46
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Regna K, Kurshan PT, Harwood BN, Jenkins AM, Lai CQ, Muskavitch MAT, Kopin AS, Draper I. A critical role for the Drosophila dopamine D1-like receptor Dop1R2 at the onset of metamorphosis. BMC DEVELOPMENTAL BIOLOGY 2016; 16:15. [PMID: 27184815 PMCID: PMC4868058 DOI: 10.1186/s12861-016-0115-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 05/08/2016] [Indexed: 01/26/2023]
Abstract
BACKGROUND Insect metamorphosis relies on temporal and spatial cues that are precisely controlled. Previous studies in Drosophila have shown that untimely activation of genes that are essential to metamorphosis results in growth defects, developmental delay and death. Multiple factors exist that safeguard these genes against dysregulated expression. The list of identified negative regulators that play such a role in Drosophila development continues to expand. RESULTS By using RNAi transgene-induced gene silencing coupled to spatio/temporal assessment, we have unraveled an important role for the Drosophila dopamine 1-like receptor, Dop1R2, in development. We show that Dop1R2 knockdown leads to pre-adult lethality. In adults that escape death, abnormal wing expansion and/or melanization defects occur. Furthermore we show that salivary gland expression of this GPCR during the late larval/prepupal stage is essential for the flies to survive through adulthood. In addition to RNAi-induced effects, treatment of larvae with the high affinity D1-like receptor antagonist flupenthixol, also results in developmental arrest, and in morphological defects comparable to those seen in Dop1R2 RNAi flies. To examine the basis for pupal lethality in Dop1R2 RNAi flies, we carried out transcriptome analysis. These studies revealed up-regulation of genes that respond to ecdysone, regulate morphogenesis and/or modulate defense/immunity. CONCLUSION Taken together our findings suggest a role for Dop1R2 in the repression of genes that coordinate metamorphosis. Premature release of this inhibition is not tolerated by the developing fly.
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Affiliation(s)
- Kimberly Regna
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Peri T Kurshan
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, 02111, USA.,Present Address: Department of Biology, Stanford University, California, 94305, USA
| | - Benjamin N Harwood
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, 02111, USA
| | - Adam M Jenkins
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Chao-Qiang Lai
- Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, 02111, USA
| | - Marc A T Muskavitch
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA.,Discovery Research, Biogen Idec, Cambridge, MA, 02142, USA
| | - Alan S Kopin
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, 02111, USA
| | - Isabelle Draper
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA, 02111, USA.
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47
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Ou J, Gao Z, Song L, Ho MS. Analysis of Glial Distribution in Drosophila Adult Brains. Neurosci Bull 2016; 32:162-70. [PMID: 26810782 DOI: 10.1007/s12264-016-0014-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 11/30/2015] [Indexed: 02/07/2023] Open
Abstract
Neurons and glia are the two major cell types in the nervous system and work closely with each other to program neuronal interplay. Traditionally, neurons are thought to be the major cells that actively regulate processes like synapse formation, plasticity, and behavioral output. Glia, on the other hand, serve a more supporting role. To date, accumulating evidence has suggested that glia are active participants in virtually every aspect of neuronal function. Despite this, fundamental features of how glia interact with neurons, and their spatial relationships, remain elusive. Here, we describe the glial cell population in Drosophila adult brains. Glial cells extend and tightly associate their processes with major structures such as the mushroom body (MB), ellipsoid body (EB), and antennal lobe (AL) in the brain. Glial cells are distributed in a more concentrated manner in the MB. Furthermore, subsets of glia exhibit distinctive association patterns around different neuronal structures. Whereas processes extended by astrocyte-like glia and ensheathing glia wrap around the MB and infiltrate into the EB and AL, cortex glia stay where cell bodies of neurons are and remain outside of the synaptic regions structured by EB or AL.
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Affiliation(s)
- Jiayao Ou
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, 200092, China
| | - Zongbao Gao
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, 200092, China
| | - Li Song
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China.,Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, 200092, China
| | - Margaret S Ho
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China. .,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai, 200092, China. .,Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai, 200092, China.
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48
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Li Y, Li D, Raisman G. Astrocytic role in synapse formation after injury. Brain Res 2015; 1645:18-21. [PMID: 26746338 DOI: 10.1016/j.brainres.2015.12.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 12/19/2015] [Indexed: 01/24/2023]
Abstract
In 1969 a paper entitled Neuronal plasticity in the septal nuclei of the adult rat proposed that new synapses are formed in the adult brain after injury (Raisman, 1969). The quantitative electron microscopic study of the timed responses to selective partial denervation of the neuropil of the adult rat septal nuclei after distant transection of the hippocampal efferent axons in the fimbria showed that the new synapses arise by sprouting of surviving adjacent synapses which selectively take over the previously denervated sites and thus restore the number of synapses to normal. This article presents the evidence for the role of perisynaptic astrocytic processes in the removal and formation of synapses and considers its significance as one of the three major divisions of the astrocytic surface in terms of the axonal responses to injury and regeneration. This article is part of a Special Issue entitled SI:50th Anniversary Issue.
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Affiliation(s)
- Ying Li
- Spinal Repair Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom.
| | - Daqing Li
- Spinal Repair Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom.
| | - Geoffrey Raisman
- Spinal Repair Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom.
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49
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Smith-Trunova S, Prithviraj R, Spurrier J, Kuzina I, Gu Q, Giniger E. Cdk5 regulates developmental remodeling of mushroom body neurons in Drosophila. Dev Dyn 2015; 244:1550-63. [PMID: 26394609 DOI: 10.1002/dvdy.24350] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/10/2015] [Accepted: 09/19/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND During metamorphosis, axons and dendrites of the mushroom body (MB) in the Drosophila central brain are remodeled extensively to support the transition from larval to adult behaviors. RESULTS We show here that the neuronal cyclin-dependent kinase, Cdk5, regulates the timing and rate of mushroom body remodeling: reduced Cdk5 activity causes a delay in pruning of MB neurites, while hyperactivation accelerates it. We further show that Cdk5 cooperates with the ubiquitin-proteasome system in this process. Finally, we show that Cdk5 modulates the first overt step in neurite disassembly, dissolution of the neuronal tubulin cytoskeleton, and provide evidence that it also acts at additional steps of MB pruning. CONCLUSIONS These data show that Cdk5 regulates the onset and extent of remodeling of the Drosophila MB. Given the wide phylogenetic conservation of Cdk5, we suggest that it is likely to play a role in developmental remodeling in other systems, as well. Moreover, we speculate that the well-established role of Cdk5 in neurodegeneration may involve some of the same cellular mechanisms that it uses during developmental remodeling.
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Affiliation(s)
- Svetlana Smith-Trunova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Ranjini Prithviraj
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Joshua Spurrier
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland.,The Johns Hopkins University/National Institutes of Health Graduate Partnership Program, National Institutes of Health, Bethesda, Maryland
| | - Irina Kuzina
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Qun Gu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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50
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Abstract
The assembly of functional neural circuits requires the combined action of progressive and regressive events. Regressive events encompass a variety of inhibitory developmental processes, including axon and dendrite pruning, which facilitate the removal of exuberant neuronal connections. Most axon pruning involves the removal of axons that had already made synaptic connections; thus, axon pruning is tightly associated with synapse elimination. In many instances, these developmental processes are regulated by the interplay between neurons and glial cells that act instructively during neural remodeling. Owing to the importance of axon and dendritic pruning, these remodeling events require precise spatial and temporal control, and this is achieved by a range of distinct molecular mechanisms. Disruption of these mechanisms results in abnormal pruning, which has been linked to brain dysfunction. Therefore, understanding the mechanisms of axon and dendritic pruning will be instrumental in advancing our knowledge of neural disease and mental disorders.
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Affiliation(s)
- Martin M Riccomagno
- Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521;
| | - Alex L Kolodkin
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
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