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Pizzirusso G, Preka E, Goikolea J, Aguilar-Ruiz C, Rodriguez-Rodriguez P, Vazquez-Cabrera G, Laterza S, Latorre-Leal M, Eroli F, Blomgren K, Maioli S, Nilsson P, Fragkopoulou A, Fisahn A, Arroyo-García LE. Dynamic microglia alterations associate with hippocampal network impairments: A turning point in amyloid pathology progression. Brain Behav Immun 2024; 119:286-300. [PMID: 38608739 DOI: 10.1016/j.bbi.2024.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/12/2024] [Accepted: 04/09/2024] [Indexed: 04/14/2024] Open
Abstract
Alzheimer's disease is a progressive neurological disorder causing memory loss and cognitive decline. The underlying causes of cognitive deterioration and neurodegeneration remain unclear, leading to a lack of effective strategies to prevent dementia. Recent evidence highlights the role of neuroinflammation, particularly involving microglia, in Alzheimer's disease onset and progression. Characterizing the initial phase of Alzheimer's disease can lead to the discovery of new biomarkers and therapeutic targets, facilitating timely interventions for effective treatments. We used the AppNL-G-F knock-in mouse model, which resembles the amyloid pathology and neuroinflammatory characteristics of Alzheimer's disease, to investigate the transition from a pre-plaque to an early plaque stage with a combined functional and molecular approach. Our experiments show a progressive decrease in the power of cognition-relevant hippocampal gamma oscillations during the early stage of amyloid pathology, together with a modification of fast-spiking interneuron intrinsic properties and postsynaptic input. Consistently, transcriptomic analyses revealed that these effects are accompanied by changes in synaptic function-associated pathways. Concurrently, homeostasis- and inflammatory-related microglia signature genes were downregulated. Moreover, we found a decrease in Iba1-positive microglia in the hippocampus that correlates with plaque aggregation and neuronal dysfunction. Collectively, these findings support the hypothesis that microglia play a protective role during the early stages of amyloid pathology by preventing plaque aggregation, supporting neuronal homeostasis, and overall preserving the oscillatory network's functionality. These results suggest that the early alteration of microglia dynamics could be a pivotal event in the progression of Alzheimer's disease, potentially triggering plaque deposition, impairment of fast-spiking interneurons, and the breakdown of the oscillatory circuitry in the hippocampus.
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Affiliation(s)
- Giusy Pizzirusso
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden; Department of Women's and Children's Health, Karolinska Institutet, Sweden
| | - Efthalia Preka
- Department of Women's and Children's Health, Karolinska Institutet, Sweden
| | - Julen Goikolea
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Celia Aguilar-Ruiz
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Patricia Rodriguez-Rodriguez
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | | | - Simona Laterza
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Maria Latorre-Leal
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Francesca Eroli
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Klas Blomgren
- Department of Women's and Children's Health, Karolinska Institutet, Sweden; Pediatric Oncology, Karolinska University Hospital, Stockholm, Sweden
| | - Silvia Maioli
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | - Per Nilsson
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden
| | | | - André Fisahn
- Department of Women's and Children's Health, Karolinska Institutet, Sweden.
| | - Luis Enrique Arroyo-García
- Department of Neurobiology, Care Sciences and Society, Division of Neurogeriatrics, Karolinska Institutet, Sweden; Department of Women's and Children's Health, Karolinska Institutet, Sweden.
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Burton SD, Malyshko CM, Urban NN. Fast-spiking interneuron detonation drives high-fidelity inhibition in the olfactory bulb. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.592874. [PMID: 38766161 PMCID: PMC11100763 DOI: 10.1101/2024.05.07.592874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Inhibitory circuits in the mammalian olfactory bulb (OB) dynamically reformat olfactory information as it propagates from peripheral receptors to downstream cortex. To gain mechanistic insight into how specific OB interneuron types support this sensory processing, we examine unitary synaptic interactions between excitatory mitral and tufted cells (MTCs), the OB projection cells, and a conserved population of anaxonic external plexiform layer interneurons (EPL-INs) using pair and quartet whole-cell recordings in acute mouse brain slices. Physiological, morphological, neurochemical, and synaptic analyses divide EPL-INs into distinct subtypes and reveal that parvalbumin-expressing fast-spiking EPL-INs (FSIs) perisomatically innervate MTCs with release-competent dendrites and synaptically detonate to mediate fast, short-latency recurrent and lateral inhibition. Sparse MTC synchronization supralinearly increases this high-fidelity inhibition, while sensory afferent activation combined with single-cell silencing reveals that individual FSIs account for a substantial fraction of total network-driven MTC lateral inhibition. OB output is thus powerfully shaped by detonation-driven high-fidelity perisomatic inhibition.
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Affiliation(s)
- Shawn D. Burton
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | | | - Nathaniel N. Urban
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
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Mesnard CS, Hays CL, Townsend LE, Barta CL, Gurumurthy CB, Thoreson WB. SYNAPTOTAGMIN-9 IN MOUSE RETINA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.27.546758. [PMID: 37425946 PMCID: PMC10327071 DOI: 10.1101/2023.06.27.546758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Synaptotagmin-9 (Syt9) is a Ca2+ sensor mediating fast synaptic release expressed in various parts of the brain. The presence and role of Syt9 in retina is unknown. We found evidence for Syt9 expression throughout the retina and created mice to conditionally eliminate Syt9 in a cre-dependent manner. We crossed Syt9fl/fl mice with Rho-iCre, HRGP-Cre, and CMV-cre mice to generate mice in which Syt9 was eliminated from rods (rodSyt9CKO), cones (coneSyt9CKO), or whole animals (CMVSyt9). CMVSyt9 mice showed an increase in scotopic electroretinogram (ERG) b-waves evoked by bright flashes with no change in a-waves. Cone-driven photopic ERG b-waves were not significantly different in CMVSyt9 knockout mice and selective elimination of Syt9 from cones had no effect on ERGs. However, selective elimination from rods decreased scotopic and photopic b-waves as well as oscillatory potentials. These changes occurred only with bright flashes where cone responses contribute. Synaptic release was measured in individual rods by recording anion currents activated by glutamate binding to presynaptic glutamate transporters. Loss of Syt9 from rods had no effect on spontaneous or depolarization-evoked release. Our data show that Syt9 is acts at multiple sites in the retina and suggest that it may play a role in regulating transmission of cone signals by rods.
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Affiliation(s)
- Chris S. Mesnard
- Truhlsen Eye Institute and Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68106, USA
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68106, USA
| | - Cassandra L. Hays
- Truhlsen Eye Institute and Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68106, USA
- Department of Medical Education, Creighton University, Omaha, NE 68178
| | - Lou E. Townsend
- Truhlsen Eye Institute and Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68106, USA
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68106, USA
| | - Cody L. Barta
- Truhlsen Eye Institute and Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68106, USA
| | | | - Wallace B. Thoreson
- Truhlsen Eye Institute and Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68106, USA
- Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68106, USA
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Ali G, Shin KC, Habbab W, Alkhadairi G, AbdelAleem A, AlShaban FA, Park Y, Stanton LW. Characterization of a loss-of-function NSF attachment protein beta mutation in monozygotic triplets affected with epilepsy and autism using cortical neurons from proband-derived and CRISPR-corrected induced pluripotent stem cell lines. Front Neurosci 2024; 17:1302470. [PMID: 38260021 PMCID: PMC10801733 DOI: 10.3389/fnins.2023.1302470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/12/2023] [Indexed: 01/24/2024] Open
Abstract
We investigated whether a homozygous recessive genetic variant of NSF attachment protein beta (NAPB) gene inherited by monozygotic triplets contributed to their phenotype of early-onset epilepsy and autism. Induced pluripotent stem cell (iPSC) lines were generated from all three probands and both parents. The NAPB genetic variation was corrected in iPSC lines from two probands by CRISPR/Cas9 gene editing. Cortical neurons were produced by directed, in vitro differentiation from all iPSC lines. These cell line-derived neurons enabled us to determine that the genetic variation in the probands causes exon skipping and complete absence of NAPB protein. Electrophysiological and transcriptomic comparisons of cortical neurons derived from parents and probands cell lines indicate that loss of NAPB function contributes to alterations in neuronal functions and likely contributed to the impaired neurodevelopment of the triplets.
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Affiliation(s)
- Gowher Ali
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Kyung Chul Shin
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Wesal Habbab
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Ghaneya Alkhadairi
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Alice AbdelAleem
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Fouad A. AlShaban
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Yongsoo Park
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Lawrence W. Stanton
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
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5
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Koss KM, Son T, Li C, Hao Y, Cao J, Churchward MA, Zhang ZJ, Wertheim JA, Derda R, Todd KG. Toward discovering a novel family of peptides targeting neuroinflammatory states of brain microglia and astrocytes. J Neurochem 2023:10.1111/jnc.15840. [PMID: 37171455 PMCID: PMC10640667 DOI: 10.1111/jnc.15840] [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: 12/16/2022] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023]
Abstract
Microglia are immune-derived cells critical to the development and healthy function of the brain and spinal cord, yet are implicated in the active pathology of many neuropsychiatric disorders. A range of functional phenotypes associated with the healthy brain or disease states has been suggested from in vivo work and were modeled in vitro as surveying, reactive, and primed sub-types of primary rat microglia and mixed microglia/astrocytes. It was hypothesized that the biomolecular profile of these cells undergoes a phenotypical change as well, and these functional phenotypes were explored for potential novel peptide binders using a custom 7 amino acid-presenting M13 phage library (SX7) to identify unique peptides that bind differentially to these respective cell types. Surveying glia were untreated, reactive were induced with a lipopolysaccharide treatment, recovery was modeled with a potent anti-inflammatory treatment dexamethasone, and priming was determined by subsequently challenging the cells with interferon gamma. Microglial function was profiled by determining the secretion of cytokines and nitric oxide, and expression of inducible nitric oxide synthase. After incubation with the SX7 phage library, populations of SX7-positive microglia and/or astrocytes were collected using fluorescence-activated cell sorting, SX7 phage was amplified in Escherichia coli culture, and phage DNA was sequenced via next-generation sequencing. Binding validation was done with synthesized peptides via in-cell westerns. Fifty-eight unique peptides were discovered, and their potential functions were assessed using a basic local alignment search tool. Peptides potentially originated from proteins ranging in function from a variety of supportive glial roles, including synapse support and pruning, to inflammatory incitement including cytokine and interleukin activation, and potential regulation in neurodegenerative and neuropsychiatric disorders.
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Affiliation(s)
- K M Koss
- Comprehensive Transplant Center and Department of Surgery, Feinberg School of Medicine, Northwestern University, Illinois, Chicago, USA
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Alberta, Edmonton, Canada
- Department of Surgery, University of Arizona College of Medicine, Arizona, Tucson, USA
| | - T Son
- Comprehensive Transplant Center and Department of Surgery, Feinberg School of Medicine, Northwestern University, Illinois, Chicago, USA
| | - C Li
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr NW, Edmonton, AB T6G 2G2, Canada
| | - Y Hao
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr NW, Edmonton, AB T6G 2G2, Canada
| | - J Cao
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr NW, Edmonton, AB T6G 2G2, Canada
- 48Hour Discovery Inc, 11421 Saskatchewan Dr NW, Edmonton, AB T6G 2M9, Canada
| | - M A Churchward
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Alberta, Edmonton, Canada
- Department of Biology and Environmental Sciences, Concordia University of Edmonton, Alberta, Edmonton, Canada
| | - Z J Zhang
- Comprehensive Transplant Center and Department of Surgery, Feinberg School of Medicine, Northwestern University, Illinois, Chicago, USA
| | - J A Wertheim
- Comprehensive Transplant Center and Department of Surgery, Feinberg School of Medicine, Northwestern University, Illinois, Chicago, USA
- Department of Surgery, University of Arizona College of Medicine, Arizona, Tucson, USA
| | - R Derda
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr NW, Edmonton, AB T6G 2G2, Canada
- 48Hour Discovery Inc, 11421 Saskatchewan Dr NW, Edmonton, AB T6G 2M9, Canada
| | - K G Todd
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Alberta, Edmonton, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Alberta, Edmonton, Canada
- Department of Biomedical Engineering, University of Alberta, Alberta, Edmonton, Canada
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6
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Ginebaugh SP, Badawi Y, Laghaei R, Mersky G, Wallace CJ, Tarr TB, Kaufhold C, Reddel S, Meriney SD. Simulations of active zone structure and function at mammalian NMJs predict that loss of calcium channels alone is not sufficient to replicate LEMS effects. J Neurophysiol 2023; 129:1259-1277. [PMID: 37073966 PMCID: PMC10202491 DOI: 10.1152/jn.00404.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 04/14/2023] [Accepted: 04/14/2023] [Indexed: 04/20/2023] Open
Abstract
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune-mediated neuromuscular disease thought to be caused by autoantibodies against P/Q-type voltage-gated calcium channels (VGCCs), which attack and reduce the number of VGCCs within transmitter release sites (active zones; AZs) at the neuromuscular junction (NMJ), resulting in neuromuscular weakness. However, patients with LEMS also have antibodies to other neuronal proteins, and about 15% of patients with LEMS are seronegative for antibodies against VGCCs. We hypothesized that a reduction in the number of P/Q-type VGCCs alone is not sufficient to explain LEMS effects on transmitter release. Here, we used a computational model to study a variety of LEMS-mediated effects on AZ organization and transmitter release constrained by electron microscopic, pharmacological, immunohistochemical, voltage imaging, and electrophysiological observations. We show that models of healthy AZs can be modified to predict the transmitter release and short-term facilitation characteristics of LEMS and that in addition to a decrease in the number of AZ VGCCs, disruption in the organization of AZ proteins, a reduction in AZ number, a reduction in the amount of synaptotagmin, and the compensatory expression of L-type channels outside the remaining AZs are important contributors to LEMS-mediated effects on transmitter release. Furthermore, our models predict that antibody-mediated removal of synaptotagmin in combination with disruption in AZ organization alone could mimic LEMS effects without the removal of VGCCs (a seronegative model). Overall, our results suggest that LEMS pathophysiology may be caused by a collection of pathological alterations to AZs at the NMJ, rather than by a simple loss of VGCCs.NEW & NOTEWORTHY We used a computational model of the active zone (AZ) in the mammalian neuromuscular junction to investigate Lambert-Eaton myasthenic syndrome (LEMS) pathophysiology. This model suggests that disruptions in presynaptic active zone organization and protein content (particularly synaptotagmin), beyond the simple removal of presynaptic calcium channels, play an important role in LEMS pathophysiology.
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Affiliation(s)
- Scott P Ginebaugh
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Yomna Badawi
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Rozita Laghaei
- Biomedical Application Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
| | - Glenn Mersky
- Biomedical Application Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
| | - Caleb J Wallace
- Biomedical Application Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
| | - Tyler B Tarr
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Cassandra Kaufhold
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Stephen Reddel
- Department of Clinical Neurology, Concord Hospital, Sydney, New South Wales, Australia
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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Synaptotagmin 9 Modulates Spontaneous Neurotransmitter Release in Striatal Neurons by Regulating Substance P Secretion. J Neurosci 2023; 43:1475-1491. [PMID: 36732068 PMCID: PMC9992334 DOI: 10.1523/jneurosci.1857-22.2023] [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: 09/29/2022] [Revised: 01/05/2023] [Accepted: 01/10/2023] [Indexed: 02/04/2023] Open
Abstract
Synaptotagmin 9 (SYT9) is a tandem C2 domain Ca2+ sensor for exocytosis in neuroendocrine cells; its function in neurons remains unclear. Here, we show that, in mixed-sex cultures, SYT9 does not trigger rapid synaptic vesicle exocytosis in mouse cortical, hippocampal, or striatal neurons, unless it is massively overexpressed. In striatal neurons, loss of SYT9 reduced the frequency of spontaneous neurotransmitter release events (minis). We delved into the underlying mechanism and discovered that SYT9 was localized to dense-core vesicles that contain substance P (SP). Loss of SYT9 impaired SP release, causing the observed decrease in mini frequency. This model is further supported by loss of function mutants. Namely, Ca2+ binding to the C2A domain of SYT9 triggered membrane fusion in vitro, and mutations that disrupted this activity abolished the ability of SYT9 to regulate both SP release and mini frequency. We conclude that SYT9 indirectly regulates synaptic transmission in striatal neurons by controlling SP release.SIGNIFICANCE STATEMENT Synaptotagmin 9 (SYT9) has been described as a Ca2+ sensor for dense-core vesicle (DCV) exocytosis in neuroendocrine cells, but its role in neurons remains unclear, despite widespread expression in the brain. This article examines the role of SYT9 in synaptic transmission across cultured cortical, hippocampal, and striatal neuronal preparations. We found that SYT9 regulates spontaneous neurotransmitter release in striatal neurons by serving as a Ca2+ sensor for the release of the neuromodulator substance P from DCVs. This demonstrates a novel role for SYT9 in neurons and uncovers a new field of study into neuromodulation by SYT9, a protein that is widely expressed in the brain.
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Pugliese A, Holland SH, Rodolico C, Lochmüller H, Spendiff S. Presynaptic Congenital Myasthenic Syndromes: Understanding Clinical Phenotypes through In vivo Models. J Neuromuscul Dis 2023; 10:731-759. [PMID: 37212067 PMCID: PMC10578258 DOI: 10.3233/jnd-221646] [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] [Accepted: 04/30/2023] [Indexed: 05/23/2023]
Abstract
Presynaptic congenital myasthenic syndromes (CMS) are a group of genetic disorders affecting the presynaptic side of the neuromuscular junctions (NMJ). They can result from a dysfunction in acetylcholine (ACh) synthesis or recycling, in its packaging into synaptic vesicles, or its subsequent release into the synaptic cleft. Other proteins involved in presynaptic endplate development and maintenance can also be impaired.Presynaptic CMS usually presents during the prenatal or neonatal period, with a severe phenotype including congenital arthrogryposis, developmental delay, and apnoeic crisis. However, milder phenotypes with proximal muscle weakness and good response to treatment have been described. Finally, many presynaptic genes are expressed in the brain, justifying the presence of additional central nervous system symptoms.Several animal models have been developed to study CMS, providing the opportunity to identify disease mechanisms and test treatment options. In this review, we describe presynaptic CMS phenotypes with a focus on in vivo models, to better understand CMS pathophysiology and define new causative genes.
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Affiliation(s)
- Alessia Pugliese
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Stephen H. Holland
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Department of Medicine, Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Neuropediatrics and Muscle Disorders, Medical Center – University of Freiburg, Faculty of Medicine, Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Sally Spendiff
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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López-Murcia FJ, Reim K, Taschenberger H. Complexins: Ubiquitously Expressed Presynaptic Regulators of SNARE-Mediated Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:255-285. [PMID: 37615870 DOI: 10.1007/978-3-031-34229-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitter release is a spatially and temporally tightly regulated process, which requires assembly and disassembly of SNARE complexes to enable the exocytosis of transmitter-loaded synaptic vesicles (SVs) at presynaptic active zones (AZs). While the requirement for the core SNARE machinery is shared by most membrane fusion processes, SNARE-mediated fusion at AZs is uniquely regulated to allow very rapid Ca2+-triggered SV exocytosis following action potential (AP) arrival. To enable a sub-millisecond time course of AP-triggered SV fusion, synapse-specific accessory SNARE-binding proteins are required in addition to the core fusion machinery. Among the known SNARE regulators specific for Ca2+-triggered SV fusion are complexins, which are almost ubiquitously expressed in neurons. This chapter summarizes the structural features of complexins, models for their molecular interactions with SNAREs, and their roles in SV fusion.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Pathology and Experimental Therapy, Institute of Neurosciences, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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10
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MacLeod KM, Pandya S. Expression and Neurotransmitter Association of the Synaptic Calcium Sensor Synaptotagmin in the Avian Auditory Brain Stem. J Assoc Res Otolaryngol 2022; 23:701-720. [PMID: 35999323 PMCID: PMC9789253 DOI: 10.1007/s10162-022-00863-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 07/12/2022] [Indexed: 01/31/2023] Open
Abstract
In the avian auditory brain stem, acoustic timing and intensity cues are processed in separate, parallel pathways via the two divisions of the cochlear nucleus, nucleus angularis (NA) and nucleus magnocellularis (NM). Differences in excitatory and inhibitory synaptic properties, such as release probability and short-term plasticity, contribute to differential processing of the auditory nerve inputs. We investigated the distribution of synaptotagmin, a putative calcium sensor for exocytosis, via immunohistochemistry and double immunofluorescence in the embryonic and hatchling chick brain stem (Gallus gallus). We found that the two major isoforms, synaptotagmin 1 (Syt1) and synaptotagmin 2 (Syt2), showed differential expression. In the NM, anti-Syt2 label was strong and resembled the endbulb terminals of the auditory nerve inputs, while anti-Syt1 label was weaker and more punctate. In NA, both isoforms were intensely expressed throughout the neuropil. A third isoform, synaptotagmin 7 (Syt7), was largely absent from the cochlear nuclei. In nucleus laminaris (NL, the target nucleus of NM), anti-Syt2 and anti-Syt7 strongly labeled the dendritic lamina. These patterns were established by embryonic day 18 and persisted to postnatal day 7. Double-labeling immunofluorescence showed that Syt1 and Syt2 were associated with vesicular glutamate transporter 2 (VGluT2), but not vesicular GABA transporter (VGAT), suggesting that these Syt isoforms were localized to excitatory, but not inhibitory, terminals. These results suggest that Syt2 is the major calcium binding protein underlying excitatory neurotransmission in the timing pathway comprising NM and NL, while Syt2 and Syt1 regulate excitatory transmission in the parallel intensity pathway via cochlear nucleus NA.
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Affiliation(s)
- Katrina M MacLeod
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Sangeeta Pandya
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
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Riggs E, Shakkour Z, Anderson CL, Carney PR. SYT1-Associated Neurodevelopmental Disorder: A Narrative Review. CHILDREN 2022; 9:children9101439. [PMID: 36291375 PMCID: PMC9601251 DOI: 10.3390/children9101439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022]
Abstract
Synaptic dysregulations often result in damaging effects on the central nervous system, resulting in a wide range of brain and neurodevelopment disorders that are caused by mutations disrupting synaptic proteins. SYT1, an identified synaptotagmin protein, plays an essential role in mediating the release of calcium-triggered neurotransmitters (NT) involved in regular synaptic vesicle exocytosis. Considering the significant role of SYT1 in the physiology of synaptic neurotransmission, dysfunction and degeneration of this protein can result in a severe neurological impairment. Genetic variants lead to a newly discovered rare disorder, known as SYT1-associated neurodevelopment disorder. In this review, we will discuss in depth the function of SYT1 in synapse and the underlying molecular mechanisms. We will highlight the genetic basis of SYT1-associated neurodevelopmental disorder along with known phenotypes, with possible interventions and direction of research.
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Affiliation(s)
- Edith Riggs
- College of Osteopathic Medicine, Kansas City University School of Medicine, Kansas City, MO 64106, USA
| | - Zaynab Shakkour
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
| | - Christopher L. Anderson
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
- Correspondence:
| | - Paul R. Carney
- School of Medicine, University of Missouri Child Health, Columbia, MO 65201, USA
- Department of Engineering, University of Missouri Biomedical Engineering, Columbia, MO 65201, USA
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12
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Synaptotagmin 2 is ectopically overexpressed in excitatory presynapses of a widely used CaMKΙΙα-Cre mouse line. iScience 2022; 25:104692. [PMID: 35856033 PMCID: PMC9287804 DOI: 10.1016/j.isci.2022.104692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 04/29/2022] [Accepted: 06/27/2022] [Indexed: 12/13/2022] Open
Abstract
The CaMKΙΙα-Cre mouse lines, possibly the most used Cre lines in neuroscience, have resulted in over 800 articles to date. Here, we demonstrate that the second most widely used CaMKΙΙα-Cre line, Tg(Camk2a-cre)2Gsc (or CamiCre), shows ectopic overexpression of synaptotagmin 2, the most efficient Ca2+ sensor for fast synchronous neurotransmitter release, in excitatory presynapses of Cre+ brains. Moreover, the upregulation of immediate-early genes and genes incorporated in bacterial artificial chromosome (BAC) transgenes, such as L-proline transporter Slc6a7, was found in Cre+ hippocampus. The copy number and integration site of the transgene are suggested to have caused the aberrant gene expression in Cre+ brains. Most importantly, CamiCre+ mice showed functional phenotypes, such as hyperactivity and enhanced associative learning, suggesting that neural activities are affected. These unexpected results suggest difficulties in interpreting results from studies using the CamiCre line and raise a warning of potential pitfalls in using Cre driver lines in general. CamiCre+ mice show the ectopic overexpression of SYT2 in excitatory presynapses CamiCre+ mice show the ectopic overexpression of SLC6A7 in hippocampal mossy fibers CamiCre+ mice show hyperactivity and enhanced associative learning Multiple copies of bacterial artificial chromosome (BAC) transgenes are integrated into the Syt2 locus
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13
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Glutamatergic synapses from the insular cortex to the basolateral amygdala encode observational pain. Neuron 2022; 110:1993-2008.e6. [PMID: 35443154 DOI: 10.1016/j.neuron.2022.03.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 01/30/2022] [Accepted: 03/23/2022] [Indexed: 02/06/2023]
Abstract
Empathic pain has attracted the interest of a substantial number of researchers studying the social transfer of pain in the sociological, psychological, and neuroscience fields. However, the neural mechanism of empathic pain remains elusive. Here, we establish a long-term observational pain model in mice and find that glutamatergic projection from the insular cortex (IC) to the basolateral amygdala (BLA) is critical for the formation of observational pain. The selective activation or inhibition of the IC-BLA projection pathway strengthens or weakens the intensity of observational pain, respectively. The synaptic molecules are screened, and the upregulated synaptotagmin-2 and RIM3 are identified as key signals in controlling the increased synaptic glutamate transmission from the IC to the BLA. Together, these results reveal the molecular and synaptic mechanisms of a previously unidentified neural pathway that regulates observational pain in mice.
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14
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Inhibition of calcium-triggered secretion by hydrocarbon-stapled peptides. Nature 2022; 603:949-956. [PMID: 35322233 PMCID: PMC8967716 DOI: 10.1038/s41586-022-04543-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 02/11/2022] [Indexed: 02/06/2023]
Abstract
Membrane fusion triggered by Ca2+ is orchestrated by a conserved set of proteins to mediate synaptic neurotransmitter release, mucin secretion and other regulated exocytic processes1–4. For neurotransmitter release, the Ca2+ sensitivity is introduced by interactions between the Ca2+ sensor synaptotagmin and the SNARE complex5, and sequence conservation and functional studies suggest that this mechanism is also conserved for mucin secretion6. Disruption of Ca2+-triggered membrane fusion by a pharmacological agent would have therapeutic value for mucus hypersecretion as it is the major cause of airway obstruction in the pathophysiology of respiratory viral infection, asthma, chronic obstructive pulmonary disease and cystic fibrosis7–11. Here we designed a hydrocarbon-stapled peptide that specifically disrupts Ca2+-triggered membrane fusion by interfering with the so-called primary interface between the neuronal SNARE complex and the Ca2+-binding C2B domain of synaptotagmin-1. In reconstituted systems with these neuronal synaptic proteins or with their airway homologues syntaxin-3, SNAP-23, VAMP8, synaptotagmin-2, along with Munc13-2 and Munc18-2, the stapled peptide strongly suppressed Ca2+-triggered fusion at physiological Ca2+ concentrations. Conjugation of cell-penetrating peptides to the stapled peptide resulted in efficient delivery into cultured human airway epithelial cells and mouse airway epithelium, where it markedly and specifically reduced stimulated mucin secretion in both systems, and substantially attenuated mucus occlusion of mouse airways. Taken together, peptides that disrupt Ca2+-triggered membrane fusion may enable the therapeutic modulation of mucin secretory pathways. Peptides that disrupt Ca2+-triggered membrane fusion may enable the therapeutic modulation of mucin secretory pathways.
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15
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Henry D, Joselevitch C, Matthews GG, Wollmuth LP. Expression and distribution of synaptotagmin family members in the zebrafish retina. J Comp Neurol 2022; 530:705-728. [PMID: 34468021 PMCID: PMC8792163 DOI: 10.1002/cne.25238] [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: 06/15/2021] [Revised: 08/21/2021] [Accepted: 08/24/2021] [Indexed: 11/10/2022]
Abstract
Synaptotagmins belong to a large family of proteins. Although various synaptotagmins have been implicated as Ca2+ sensors for vesicle replenishment and release at conventional synapses, their roles at retinal ribbon synapses remain incompletely understood. Zebrafish is a widely used experimental model for retinal research. We therefore investigated the homology between human, rat, mouse, and zebrafish synaptotagmins 1-10 using a bioinformatics approach. We also characterized the expression and distribution of various synaptotagmin (syt) genes in the zebrafish retina using RT-PCR, qPCR, and in situhybridization, focusing on the family members whose products likely underlie Ca2+ -dependent exocytosis in the central nervous system (synaptotagmins 1, 2, 5, and 7). Most zebrafish synaptotagmins are well conserved and can be grouped in the same classes as mammalian synaptotagmins, based on crucial amino acid residues needed for coordinating Ca2+ binding and determining phospholipid binding affinity. The only exception is synaptotagmin 1b, which lacks 34 amino acid residues in the C2B domain and is therefore unlikely to bind Ca2+ there. Additionally, the products of zebrafish syt5a and syt5b genes share identity with mammalian class 1 and 5 synaptotagmins. Zebrafish syt1, syt2, syt5, and syt7 paralogues are found in the zebrafish brain, eye, and retina, excepting syt1b, which is only present in the brain. The complementary expression pattern of the remaining paralogues in the retina suggests that syt1a and syt5a may underlie synchronous release and syt7a and syt7b may mediate asynchronous release or other Ca2+ -dependent processes in different retinal neurons.
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Affiliation(s)
- Diane Henry
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794-5230,Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY 11794-5230
| | - Christina Joselevitch
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794-5230,Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY 11794-5230
| | - Gary G. Matthews
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794-5230,Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY 11794-5230
| | - Lonnie P. Wollmuth
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794-5230,Department of Biochemistry & Cell Biology, Stony Brook University, Stony Brook, NY 11794-5230,Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY 11794-5230
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16
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Martínez-Valencia A, Ramírez-Santiago G, De-Miguel FF. Dynamics of Neuromuscular Transmission Reproduced by Calcium-Dependent and Reversible Serial Transitions in the Vesicle Fusion Complex. Front Synaptic Neurosci 2022; 13:785361. [PMID: 35242023 PMCID: PMC8885725 DOI: 10.3389/fnsyn.2021.785361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/30/2021] [Indexed: 11/28/2022] Open
Abstract
Neuromuscular transmission, from spontaneous release to facilitation and depression, was accurately reproduced by a mechanistic kinetic model of sequential maturation transitions in the molecular fusion complex. The model incorporates three predictions. First, calcium-dependent forward transitions take vesicles from docked to preprimed to primed states, followed by fusion. Second, prepriming and priming are reversible. Third, fusion and recycling are unidirectional. The model was fed with experimental data from previous studies, whereas the backward (β) and recycling (ρ) rate constant values were fitted. Classical experiments were successfully reproduced with four transition states in the model when every forward (α) rate constant had the same value, and both backward rate constants were 50–100 times larger. Such disproportion originated an abruptly decreasing gradient of resting vesicles from docked to primed states. By contrast, a three-state version of the model failed to reproduce the dynamics of transmission by using the same set of parameters. Simulations predict the following: (1) Spontaneous release reflects primed to fusion spontaneous transitions. (2) Calcium elevations synchronize the series of forward transitions that lead to fusion. (3) Facilitation reflects a transient increase of priming following the calcium-dependent maturation transitions. (4) The calcium sensors that produce facilitation are those that evoke the transitions form docked to primed states. (5) Backward transitions and recycling restore the resting state. (6) Depression reflects backward transitions and slow recycling after intense release. Altogether, our results predict that fusion is produced by one calcium sensor, whereas the modulation of the number of vesicles that fuse depends on the calcium sensors that promote the early transition states. Such finely tuned kinetics offers a mechanism for collective non-linear transitional adaptations of a homogeneous vesicle pool to the ever-changing pattern of electrical activity in the neuromuscular junction.
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Affiliation(s)
- Alejandro Martínez-Valencia
- Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Francisco F. De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- *Correspondence: Francisco F. De-Miguel,
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17
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De-Miguel FF. The Thermodynamically Expensive Contribution of Three Calcium Sources to Somatic Release of Serotonin. Int J Mol Sci 2022; 23:ijms23031495. [PMID: 35163419 PMCID: PMC8836226 DOI: 10.3390/ijms23031495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 02/01/2023] Open
Abstract
The soma, dendrites and axon of neurons may display calcium-dependent release of transmitters and peptides. Such release is named extrasynaptic for occurring in absence of synaptic structures. This review describes the cooperative actions of three calcium sources on somatic exocytosis. Emphasis is given to the somatic release of serotonin by the classical leech Retzius neuron, which has allowed detailed studies on the fine steps from excitation to exocytosis. Trains of action potentials induce transmembrane calcium entry through L-type channels. For action potential frequencies above 5 Hz, summation of calcium transients on individual action potentials activates the second calcium source: ryanodine receptors produce calcium-induced calcium release. The resulting calcium tsunami activates mitochondrial ATP synthesis to fuel transport of vesicles to the plasma membrane. Serotonin that is released maintains a large-scale exocytosis by activating the third calcium source: serotonin autoreceptors coupled to phospholipase C promote IP3 production. Activated IP3 receptors in peripheral endoplasmic reticulum release calcium that promotes vesicle fusion. The Swiss-clock workings of the machinery for somatic exocytosis has a striking disadvantage. The essential calcium-releasing endoplasmic reticulum near the plasma membrane hinders the vesicle transport, drastically reducing the thermodynamic efficiency of the ATP expenses and elevating the energy cost of release.
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Affiliation(s)
- Francisco F De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
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18
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Takikawa K, Nishimune H. Similarity and Diversity of Presynaptic Molecules at Neuromuscular Junctions and Central Synapses. Biomolecules 2022; 12:biom12020179. [PMID: 35204679 PMCID: PMC8961632 DOI: 10.3390/biom12020179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic transmission is essential for controlling motor functions and maintaining brain functions such as walking, breathing, cognition, learning, and memory. Neurotransmitter release is regulated by presynaptic molecules assembled in active zones of presynaptic terminals. The size of presynaptic terminals varies, but the size of a single active zone and the types of presynaptic molecules are highly conserved among neuromuscular junctions (NMJs) and central synapses. Three parameters play an important role in the determination of neurotransmitter release properties at NMJs and central excitatory/inhibitory synapses: the number of presynaptic molecular clusters, the protein families of the presynaptic molecules, and the distance between presynaptic molecules and voltage-gated calcium channels. In addition, dysfunction of presynaptic molecules causes clinical symptoms such as motor and cognitive decline in patients with various neurological disorders and during aging. This review focuses on the molecular mechanisms responsible for the functional similarities and differences between excitatory and inhibitory synapses in the peripheral and central nervous systems, and summarizes recent findings regarding presynaptic molecules assembled in the active zone. Furthermore, we discuss the relationship between functional alterations of presynaptic molecules and dysfunction of NMJs or central synapses in diseases and during aging.
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Affiliation(s)
- Kenji Takikawa
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
| | - Hiroshi Nishimune
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu-shi, Tokyo 183-8538, Japan
- Correspondence: ; Tel.: +81-3-3964-3241
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19
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McMeekin LJ, Joyce KL, Jenkins LM, Bohannon BM, Patel KD, Bohannon AS, Patel A, Fox SN, Simmons MS, Day JJ, Kralli A, Crossman DK, Cowell RM. Estrogen-related Receptor Alpha (ERRα) is Required for PGC-1α-dependent Gene Expression in the Mouse Brain. Neuroscience 2021; 479:70-90. [PMID: 34648866 PMCID: PMC9124582 DOI: 10.1016/j.neuroscience.2021.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 09/15/2021] [Accepted: 10/04/2021] [Indexed: 11/27/2022]
Abstract
Deficiency in peroxisome proliferator-activated receptor gamma coactivator 1-alpha. (PGC-1α) expression or function is implicated in numerous neurological and psychiatric disorders. PGC-1α is required for the expression of genes involved in synchronous neurotransmitter release, axonal integrity, and metabolism, especially in parvalbumin-positive interneurons. As a transcriptional coactivator, PGC-1α requires transcription factors to specify cell-type-specific gene programs; while much is known about these factors in peripheral tissues, it is unclear if PGC-1α utilizes these same factors in neurons. Here, we identified putative transcription factors controlling PGC-1α-dependent gene expression in the brain using bioinformatics and then validated the role of the top candidate in a knockout mouse model. We transcriptionally profiled cells overexpressing PGC-1α and searched for over-represented binding motifs in the promoters of upregulated genes. Binding sites of the estrogen-related receptor (ERR) family of transcription factors were enriched, and blockade of ERRα attenuated PGC-1α-mediated induction of mitochondrial and synaptic genes in cell culture. Localization in the mouse brain revealed enrichment of ERRα expression in parvalbumin-expressing neurons with tight correlation of expression with PGC-1α across brain regions. In ERRα null mice, PGC-1α-dependent genes were reduced in multiple regions, including neocortex, hippocampus, and cerebellum, though not to the extent observed in PGC-1α null mice. Behavioral assessment revealed ambulatory hyperactivity in response to amphetamine and impairments in sensorimotor gating without the overt motor impairment characteristic of PGC-1α null mice. These data suggest that ERRα is required for normal levels of expression of PGC-1α-dependent genes in neurons but that additional factors may be involved in their regulation.
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Affiliation(s)
- L J McMeekin
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - K L Joyce
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - L M Jenkins
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - B M Bohannon
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - K D Patel
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA
| | - A S Bohannon
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - A Patel
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - S N Fox
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - M S Simmons
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA.
| | - J J Day
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - A Kralli
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - D K Crossman
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - R M Cowell
- Department of Neuroscience, Drug Discovery Division, Southern Research, Birmingham, AL 35205, USA; Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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20
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Gorzi A, Jafari F, Allahmoradi N, Rahmani A, Krause Neto W. Training Intensity, Not Duration, May Be Key to Upregulating Presynaptic Proteins of Calcium Dynamics and Calcium-Dependent Exocytosis in Fast- and Slow-Twitch Skeletal Muscles, in Addition to Maintaining Performance After Detraining. Mol Neurobiol 2021; 58:6670-6683. [PMID: 34608606 DOI: 10.1007/s12035-021-02576-7] [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: 07/27/2021] [Accepted: 09/22/2021] [Indexed: 10/20/2022]
Abstract
Neuromuscular adaptations are essential for improving athletic performance. However, little is known about the effect of different endurance training protocols and their subsequent detraining on the gene expression of critical factors for neuromuscular synaptic transmission. Therefore, this study investigated the effects of endurance training (high-intensity interval training [HIIT], continuous [cEND], mixed interval [Mix], and all protocols combined [Comb]) and detraining on performance and gene expression (GE) of the alpha-1a, synaptotagmin II (Syt-II), synaptobrevin II (Vamp2), and acetylcholinesterase (AChE) in the gastrocnemius and soleus of Wistar rats. Eighty rodents were randomly divided into control, HIIT, cEND, Mix, Comb, and detraining groups. The rodents trained for 6 weeks (5 × /week), followed by 2 weeks of detraining. Performance improved in all training groups and decreased following detraining (p < 0.05), except HIIT. In the gastrocnemius, alpha-1a GE was upregulated in the Mix. Syt-II and AChE GE were upregulated in HIIT, Mix, and Comb. Vamp2 GE was upregulated in all groups. In the soleus, alpha-1a GE was upregulated in HIIT, Mix, and Comb. Syt-II and Vamp2 GE were upregulated in all groups. AChE GE was upregulated in cEND, Mix, and Comb. Detraining downregulated mostly the gene expression in the skeletal muscles. We conclude that training intensity appears to be a key factor for the upregulation of molecules involved in neuromuscular synaptic transmission. Such changes occur to be involved in improving running performance. On the other hand, detraining negatively affects synaptic transmission and performance.
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Affiliation(s)
- Ali Gorzi
- Department of Sport Sciences, University of Zanjan, Zanjan, Iran.
| | - Fatemeh Jafari
- Department of Sport Sciences, University of Zanjan, Zanjan, Iran
| | | | - Ahmad Rahmani
- Department of Sport Sciences, University of Zanjan, Zanjan, Iran
| | - Walter Krause Neto
- Department of Physical Education, Laboratory of Morphoquantitative Studies and Immunohistochemistry, São Judas Tadeu University, 546 - Mooca Unit, P.O box 03166-000, São Paulo, SP, Brazil.
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21
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Knockin mouse models demonstrate differential contributions of synaptotagmin-1 and -2 as receptors for botulinum neurotoxins. PLoS Pathog 2021; 17:e1009994. [PMID: 34662366 PMCID: PMC8553082 DOI: 10.1371/journal.ppat.1009994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 10/28/2021] [Accepted: 09/30/2021] [Indexed: 12/11/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most potent toxins known and are also utilized to treat a wide range of disorders including muscle spasm, overactive bladder, and pain. BoNTs' ability to target neurons determines their specificity, potency, and therapeutic efficacy. Homologous synaptic vesicle membrane proteins synaptotagmin-1 (Syt1) and synaptotagmin-2 (Syt2) have been identified as receptors for BoNT family members including BoNT/B, DC, and G, but their contributions at physiologically relevant toxin concentrations in vivo have yet to be validated and established. Here we generated two knockin mutant mouse models containing three designed point-mutations that specifically disrupt BoNT binding in endogenous Syt1 or Syt2, respectively. Utilizing digit abduction score assay by injecting toxins into the leg muscle, we found that Syt1 mutant mice showed similar sensitivity as the wild type mice, whereas Syt2 mutant mice showed reduced sensitivity to BoNT/B, DC, and G, demonstrating that Syt2 is the dominant receptor at skeletal neuromuscular junctions. We further developed an in vivo bladder injection assay for analyzing BoNT action on bladder tissues and demonstrated that Syt1 is the dominant toxin receptor in autonomic nerves controlling bladder tissues. These findings establish the critical role of protein receptors for the potency and specificity of BoNTs in vivo and demonstrate the differential contributions of Syt1 and Syt2 in two sets of clinically relevant target tissues.
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22
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Vevea JD, Kusick GF, Courtney KC, Chen E, Watanabe S, Chapman ER. Synaptotagmin 7 is targeted to the axonal plasma membrane through γ-secretase processing to promote synaptic vesicle docking in mouse hippocampal neurons. eLife 2021; 10:e67261. [PMID: 34543184 PMCID: PMC8452306 DOI: 10.7554/elife.67261] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 08/27/2021] [Indexed: 12/28/2022] Open
Abstract
Synaptotagmin 7 (SYT7) has emerged as a key regulator of presynaptic function, but its localization and precise role in the synaptic vesicle cycle remain the subject of debate. Here, we used iGluSnFR to optically interrogate glutamate release, at the single-bouton level, in SYT7KO-dissociated mouse hippocampal neurons. We analyzed asynchronous release, paired-pulse facilitation, and synaptic vesicle replenishment and found that SYT7 contributes to each of these processes to different degrees. 'Zap-and-freeze' electron microscopy revealed that a loss of SYT7 diminishes docking of synaptic vesicles after a stimulus and inhibits the recovery of depleted synaptic vesicles after a stimulus train. SYT7 supports these functions from the axonal plasma membrane, where its localization and stability require both γ-secretase-mediated cleavage and palmitoylation. In summary, SYT7 is a peripheral membrane protein that controls multiple modes of synaptic vesicle (SV) exocytosis and plasticity, in part, through enhancing activity-dependent docking of SVs.
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Affiliation(s)
- Jason D Vevea
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Grant F Kusick
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Kevin C Courtney
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Erin Chen
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
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23
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Human-Relevant Sensitivity of iPSC-Derived Human Motor Neurons to BoNT/A1 and B1. Toxins (Basel) 2021; 13:toxins13080585. [PMID: 34437455 PMCID: PMC8402508 DOI: 10.3390/toxins13080585] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/10/2021] [Accepted: 08/19/2021] [Indexed: 01/31/2023] Open
Abstract
The application of botulinum neurotoxins (BoNTs) for medical treatments necessitates a potency quantification of these lethal bacterial toxins, resulting in the use of a large number of test animals. Available alternative methods are limited in their relevance, as they are based on rodent cells or neuroblastoma cell lines or applicable for single toxin serotypes only. Here, human motor neurons (MNs), which are the physiological target of BoNTs, were generated from induced pluripotent stem cells (iPSCs) and compared to the neuroblastoma cell line SiMa, which is often used in cell-based assays for BoNT potency determination. In comparison with the mouse bioassay, human MNs exhibit a superior sensitivity to the BoNT serotypes A1 and B1 at levels that are reflective of human sensitivity. SiMa cells were able to detect BoNT/A1, but with much lower sensitivity than human MNs and appear unsuitable to detect any BoNT/B1 activity. The MNs used for these experiments were generated according to three differentiation protocols, which resulted in distinct sensitivity levels. Molecular parameters such as receptor protein concentration and electrical activity of the MNs were analyzed, but are not predictive for BoNT sensitivity. These results show that human MNs from several sources should be considered in BoNT testing and that human MNs are a physiologically relevant model, which could be used to optimize current BoNT potency testing.
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ATR regulates neuronal activity by modulating presynaptic firing. Nat Commun 2021; 12:4067. [PMID: 34210973 PMCID: PMC8249387 DOI: 10.1038/s41467-021-24217-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 06/01/2021] [Indexed: 02/06/2023] Open
Abstract
Ataxia Telangiectasia and Rad3-related (ATR) protein, as a key DNA damage response (DDR) regulator, plays an essential function in response to replication stress and controls cell viability. Hypomorphic mutations of ATR cause the human ATR-Seckel syndrome, characterized by microcephaly and intellectual disability, which however suggests a yet unknown role for ATR in non-dividing cells. Here we show that ATR deletion in postmitotic neurons does not compromise brain development and formation; rather it enhances intrinsic neuronal activity resulting in aberrant firing and an increased epileptiform activity, which increases the susceptibility of ataxia and epilepsy in mice. ATR deleted neurons exhibit hyper-excitability, associated with changes in action potential conformation and presynaptic vesicle accumulation, independent of DDR signaling. Mechanistically, ATR interacts with synaptotagmin 2 (SYT2) and, without ATR, SYT2 is highly upregulated and aberrantly translocated to excitatory neurons in the hippocampus, thereby conferring a hyper-excitability. This study identifies a physiological function of ATR, beyond its DDR role, in regulating neuronal activity.
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25
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Wang QW, Wang YH, Wang B, Chen Y, Lu SY, Yao J. Synaptotagmin-7-mediated activation of spontaneous NMDAR currents is disrupted in bipolar disorder susceptibility variants. PLoS Biol 2021; 19:e3001323. [PMID: 34228711 PMCID: PMC8284830 DOI: 10.1371/journal.pbio.3001323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 07/16/2021] [Accepted: 06/15/2021] [Indexed: 11/19/2022] Open
Abstract
Synaptotagmin-7 (Syt7) plays direct or redundant Ca2+ sensor roles in multiple forms of vesicle exocytosis in synapses. Here, we show that Syt7 is a redundant Ca2+ sensor with Syt1/Doc2 to drive spontaneous glutamate release, which functions uniquely to activate the postsynaptic GluN2B-containing NMDARs that significantly contribute to mental illness. In mouse hippocampal neurons lacking Syt1/Doc2, Syt7 inactivation largely diminishes spontaneous release. Using 2 approaches, including measuring Ca2+ dose response and substituting extracellular Ca2+ with Sr2+, we detect that Syt7 directly triggers spontaneous release via its Ca2+ binding motif to activate GluN2B-NMDARs. Furthermore, modifying the localization of Syt7 in the active zone still allows Syt7 to drive spontaneous release, but the GluN2B-NMDAR activity is abolished. Finally, Syt7 SNPs identified in bipolar disorder patients destroy the function of Syt7 in spontaneous release in patient iPSC-derived and mouse hippocampal neurons. Therefore, Syt7 could contribute to neuropsychiatric disorders through driving spontaneous glutamate release.
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Affiliation(s)
- Qiu-Wen Wang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ying-Han Wang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Bing Wang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yun Chen
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Si-Yao Lu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jun Yao
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
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Maselli RA, Wei DT, Hodgson TS, Sampson JB, Vazquez J, Smith HL, Pytel P, Ferns M. Dominant and recessive congenital myasthenic syndromes caused by SYT2 mutations. Muscle Nerve 2021; 64:219-224. [PMID: 34037996 DOI: 10.1002/mus.27332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/14/2021] [Accepted: 05/19/2021] [Indexed: 01/11/2023]
Abstract
INTRODUCTION/AIMS We studied a patient with a congenital myasthenic syndrome (CMS) caused by a dominant mutation in the synaptotagmin 2 gene (SYT2) and compared the clinical features of this patient with those of a previously described patient with a recessive mutation in the same gene. METHODS We performed electrodiagnostic (EDX) studies, genetic studies, muscle biopsy, microelectrode recordings and electron microscopy (EM). RESULTS Both patients presented with muscle weakness and bulbar deficits, which were worse in the recessive form. EDX studies showed presynaptic failure, which was more prominent in the recessive form. Microelectrode studies in the dominant form showed a marked reduction of the quantal content, which increased linearly with higher frequencies of nerve stimulation. The MEPP frequencies were normal at rest but increased markedly with higher frequencies of nerve stimulation. The EM demonstrated overdeveloped postsynaptic folding, and abundant endosomes, multivesicular bodies and degenerative lamellar bodies inside small nerve terminals. DISCUSSION The recessive form of CMS caused by a SYT2 mutation showed far more severe clinical manifestations than the dominant form. The pathogenesis of the dominant form likely involves a dominant-negative effect due to disruption of the dual function of synaptotagmin as a Ca2+ -sensor and modulator of synaptic vesicle exocytosis.
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Affiliation(s)
- Ricardo A Maselli
- Department of Neurology, University of California Davis, Sacramento, California, USA
| | - David T Wei
- Department of Neurology, University of California Davis, Sacramento, California, USA
| | - Trent S Hodgson
- Kaiser Permanente Oakland Medical Center, Oakland, California, USA
| | - Jacinda B Sampson
- Department of Neurology, Stanford University, Palo Alto, California, USA
| | - Jessica Vazquez
- Department of Neurology, University of California Davis, Sacramento, California, USA
| | - Heather L Smith
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
| | - Peter Pytel
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
| | - Michael Ferns
- Department of Anesthesiology, University of California Davis, Davis, California, USA
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27
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Decoding the Transcriptional Response to Ischemic Stroke in Young and Aged Mouse Brain. Cell Rep 2021; 31:107777. [PMID: 32553170 DOI: 10.1016/j.celrep.2020.107777] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 03/25/2020] [Accepted: 05/26/2020] [Indexed: 12/17/2022] Open
Abstract
Ischemic stroke is a well-recognized disease of aging, yet it is unclear how the age-dependent vulnerability occurs and what are the underlying mechanisms. To address these issues, we perform a comprehensive RNA-seq analysis of aging, ischemic stroke, and their interaction in 3- and 18-month-old mice. We assess differential gene expression across injury status and age, estimate cell type proportion changes, assay the results against a range of transcriptional signatures from the literature, and perform unsupervised co-expression analysis, identifying modules of genes with varying response to injury. We uncover downregulation of axonal and synaptic maintenance genetic program, and increased activation of type I interferon (IFN-I) signaling following stroke in aged mice. Together, these results paint a picture of ischemic stroke as a complex age-related disease and provide insights into interaction of aging and stroke on cellular and molecular level.
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28
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Thaker H, Zhang S, Diamond DA, Dong M. Beyond botulinum neurotoxin A for chemodenervation of the bladder. Curr Opin Urol 2021; 31:140-146. [PMID: 33394765 DOI: 10.1097/mou.0000000000000843] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Botulinum neurotoxin A (BoNT/A), or Botox, is a popular option for overactive bladder (OAB) and neurogenic bladder (NGB) with or without incontinence. This review aims to discuss the clinical outcomes of BoNT in adult and pediatric bladder conditions, and introduces the potential benefit of novel, engineered neurotoxins beyond BoNT/A. RECENT FINDINGS A large volume of evidence supports the use of Botox for OAB (to reduce urgency, frequency and incontinence episodes), and for NGB (to decrease incontinence and improve bladder capacity and detrusor pressures). Botox is now also Food & Drug Administration (FDA)-approved for pediatric neurogenic detrusor overactivity. However, urinary retention, diminished response over time and treatment failures are prevalent issues with Botox. Modifying natural BoNTs or forming chimeric toxins are alternatives to BoNT/A that may have higher efficacy and lower side-effect profile. One example is BoNT/BMY-WW. This novel engineered toxin binds to a more commonly expressed synaptotagmin receptor, with potentially more potent paralytic effect and less capacity for systemic diffusion. SUMMARY Novel engineered neurotoxins may be the next frontier in OAB and NGB therapy.
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Affiliation(s)
- Hatim Thaker
- Department of Urology, Boston Children's Hospital, Harvard Medical School
| | - Sicai Zhang
- Department of Urology, Boston Children's Hospital, Harvard Medical School.,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - David A Diamond
- Department of Urology, Boston Children's Hospital, Harvard Medical School
| | - Min Dong
- Department of Urology, Boston Children's Hospital, Harvard Medical School.,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
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29
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Complexin Suppresses Spontaneous Exocytosis by Capturing the Membrane-Proximal Regions of VAMP2 and SNAP25. Cell Rep 2021; 32:107926. [PMID: 32698012 PMCID: PMC7116205 DOI: 10.1016/j.celrep.2020.107926] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 02/28/2020] [Accepted: 06/26/2020] [Indexed: 01/29/2023] Open
Abstract
The neuronal protein complexin contains multiple domains that exert clamping and facilitatory functions to tune spontaneous and action potential-triggered synaptic release. We address the clamping mechanism and show that the accessory helix of complexin arrests assembly of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex that forms the core machinery of intracellular membrane fusion. In a reconstituted fusion assay, site-and stage-specific photo-cross-linking reveals that, prior to fusion, the complexin accessory helix laterally binds the membrane-proximal C-terminal ends of SNAP25 and VAMP2. Corresponding complexin interface mutants selectively increase spontaneous release of neuro-transmitters in living neurons, implying that the accessory helix suppresses final zippering/assembly of the SNARE four-helix bundle by restraining VAMP2 and SNAP25.
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30
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Beijer D, Baets J. The expanding genetic landscape of hereditary motor neuropathies. Brain 2021; 143:3540-3563. [PMID: 33210134 DOI: 10.1093/brain/awaa311] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/15/2020] [Accepted: 07/27/2020] [Indexed: 12/12/2022] Open
Abstract
Hereditary motor neuropathies are clinically and genetically diverse disorders characterized by length-dependent axonal degeneration of lower motor neurons. Although currently as many as 26 causal genes are known, there is considerable missing heritability compared to other inherited neuropathies such as Charcot-Marie-Tooth disease. Intriguingly, this genetic landscape spans a discrete number of key biological processes within the peripheral nerve. Also, in terms of underlying pathophysiology, hereditary motor neuropathies show striking overlap with several other neuromuscular and neurological disorders. In this review, we provide a current overview of the genetic spectrum of hereditary motor neuropathies highlighting recent reports of novel genes and mutations or recent discoveries in the underlying disease mechanisms. In addition, we link hereditary motor neuropathies with various related disorders by addressing the main affected pathways of disease divided into five major processes: axonal transport, tRNA aminoacylation, RNA metabolism and DNA integrity, ion channels and transporters and endoplasmic reticulum.
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Affiliation(s)
- Danique Beijer
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
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31
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Function of Drosophila Synaptotagmins in membrane trafficking at synapses. Cell Mol Life Sci 2021; 78:4335-4364. [PMID: 33619613 PMCID: PMC8164606 DOI: 10.1007/s00018-021-03788-9] [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: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
The Synaptotagmin (SYT) family of proteins play key roles in regulating membrane trafficking at neuronal synapses. Using both Ca2+-dependent and Ca2+-independent interactions, several SYT isoforms participate in synchronous and asynchronous fusion of synaptic vesicles (SVs) while preventing spontaneous release that occurs in the absence of stimulation. Changes in the function or abundance of the SYT1 and SYT7 isoforms alter the number and route by which SVs fuse at nerve terminals. Several SYT family members also regulate trafficking of other subcellular organelles at synapses, including dense core vesicles (DCV), exosomes, and postsynaptic vesicles. Although SYTs are linked to trafficking of multiple classes of synaptic membrane compartments, how and when they interact with lipids, the SNARE machinery and other release effectors are still being elucidated. Given mutations in the SYT family cause disorders in both the central and peripheral nervous system in humans, ongoing efforts are defining how these proteins regulate vesicle trafficking within distinct neuronal compartments. Here, we review the Drosophila SYT family and examine their role in synaptic communication. Studies in this invertebrate model have revealed key similarities and several differences with the predicted activity of their mammalian counterparts. In addition, we highlight the remaining areas of uncertainty in the field and describe outstanding questions on how the SYT family regulates membrane trafficking at nerve terminals.
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32
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Lekholm E, Ceder MM, Forsberg EC, Schiöth HB, Fredriksson R. Differentiation of two human neuroblastoma cell lines alters SV2 expression patterns. Cell Mol Biol Lett 2021; 26:5. [PMID: 33588752 PMCID: PMC7885392 DOI: 10.1186/s11658-020-00243-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 12/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The synaptic vesicle glycoprotein 2 (SV2) family is essential to the synaptic machinery involved in neurotransmission and vesicle recycling. The isoforms SV2A, SV2B and SV2C are implicated in neurological diseases such as epilepsy, Alzheimer's and Parkinson's disease. Suitable cell systems for studying regulation of these proteins are essential. Here we present gene expression data of SV2A, SV2B and SV2C in two human neuroblastoma cell lines after differentiation. METHODS Human neuroblastoma cell lines SiMa and IMR-32 were treated for seven days with growth supplements (B-27 and N-2), all-trans-retinoic acid (ATRA) or vasoactive intestinal peptide (VIP) and gene expression levels of SV2 and neuronal targets were analyzed. RESULTS The two cell lines reacted differently to the treatments, and only one of the three SV2 isoforms was affected at a time. SV2B and choline O-acetyltransferase (CHAT) expression was changed in concert after growth supplement treatment, decreasing in SiMa cells while increasing in IMR-32. ATRA treatment resulted in no detected changes in SV2 expression in either cell line while VIP increased both SV2C and dopamine transporter (DAT) in IMR-32 cells. CONCLUSION The synergistic expression patterns between SV2B and CHAT as well as between SV2C and DAT mirror the connectivity between these targets found in disease models and knock-out animals, although here no genetic alteration was made. These cell lines and differentiation treatments could possibly be used to study SV2 regulation and function.
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Affiliation(s)
- Emilia Lekholm
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden. .,Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
| | - Mikaela M Ceder
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Erica C Forsberg
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Helgi B Schiöth
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden.,Institute for Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Robert Fredriksson
- Molecular Neuropharmacology, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
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33
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Yue Z, Tian E, Chen Y, Luo L, Yang L, He L, Li L, Wang J. The adverse effects of acrylamide exposure on the early development of marine medaka (Oryzias melastigma) and its mechanisms. MARINE POLLUTION BULLETIN 2021; 163:111875. [PMID: 33422830 DOI: 10.1016/j.marpolbul.2020.111875] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/16/2020] [Accepted: 11/22/2020] [Indexed: 06/12/2023]
Abstract
Acrylamide (AA) can have deleterious effects on freshwater fish. However, its adverse effects on euryhaline fish are still unknown. In this study, embryos of Oryzias melastigma were exposed to different concentrations of AA to investigate its effect on early developmental disorders. After 21 days of exposure, AA significantly inhibited the hatching rate and delayed the hatching time of embryos, and led to developmental delay, teratogenesis, and locomotion impairments in larvae. RNA-sequencing data of larvae indicated that AA upregulated the expression of hemoglobin and myoglobin involved in oxygen transport and angiopoietin 1, integrin, and matrix metallopeptidases related to angiogenesis and downregulated the expression of early growth response genes and synaptotagmin-2 related to neural plasticity and neurotransmitter release. Overall, our study showed that AA caused deleterious effects on the early development of euryhaline fish through hypoxic stress and neurotoxicity, providing a scientific basis for the environmental risk assessment of marine AA.
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Affiliation(s)
- Zonghao Yue
- College of Life Sciences and Agronomy, Zhoukou Normal University, Zhoukou 466001, China
| | - Erli Tian
- College of Life Sciences and Agronomy, Zhoukou Normal University, Zhoukou 466001, China
| | - Yanjuan Chen
- School of Mechanical and Electrical Engineering, Zhoukou Normal University, Zhoukou 466001, China
| | - Liumin Luo
- School of Mechanical and Electrical Engineering, Zhoukou Normal University, Zhoukou 466001, China
| | - Licheng Yang
- College of Life Sciences and Agronomy, Zhoukou Normal University, Zhoukou 466001, China
| | - Le He
- College of Life Sciences and Agronomy, Zhoukou Normal University, Zhoukou 466001, China
| | - Lili Li
- College of Life Sciences and Agronomy, Zhoukou Normal University, Zhoukou 466001, China.
| | - Jun Wang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
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34
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Goode C, Voeun M, Ncube D, Eisen J, Washbourne P, Tallafuss A. Late onset of Synaptotagmin 2a expression at synapses relevant to social behavior. J Comp Neurol 2021; 529:2176-2188. [PMID: 33491202 DOI: 10.1002/cne.25084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/30/2020] [Accepted: 11/23/2020] [Indexed: 12/15/2022]
Abstract
As they form, synapses go through various stages of maturation and refinement. These steps are linked to significant changes in synaptic function, potentially resulting in emergence and maturation of behavioral outputs. Synaptotagmins are calcium-sensing proteins of the synaptic vesicle exocytosis machinery, and changes in Synaptotagmin proteins at synapses have significant effects on vesicle release and synaptic function. Here, we examined the distribution of the synaptic vesicle protein Synaptotagmin 2a (Syt2a) during development of the zebrafish nervous system. Syt2a is widely distributed throughout the midbrain and hindbrain early during larval development but very weakly expressed in the forebrain. Later in development, Syt2a expression levels in the forebrain increase, particularly in regions associated with social behavior, and most intriguingly, around the time social behavior becomes apparent. We provide evidence that Syt2a localizes to synapses onto neurons implicated in social behavior in the ventral forebrain and show that Syt2a is colocalized with tyrosine hydroxylase, a biosynthetic enzyme in the dopamine pathway. Our results suggest a developmentally important role for Syt2a in maturing synapses in the forebrain, coinciding with the emergence of social behavior.
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Affiliation(s)
- Collette Goode
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Mae Voeun
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Denver Ncube
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Judith Eisen
- Institute of Neuroscience, University of Oregon, Eugene, USA
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35
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Bauché S, Sureau A, Sternberg D, Rendu J, Buon C, Messéant J, Boëx M, Furling D, Fauré J, Latypova X, Gelot AB, Mayer M, Mary P, Whalen S, Fournier E, Cloix I, Remerand G, Laffargue F, Nougues MC, Fontaine B, Eymard B, Isapof A, Strochlic L. New recessive mutations in SYT2 causing severe presynaptic congenital myasthenic syndromes. NEUROLOGY-GENETICS 2020; 6:e534. [PMID: 33659639 PMCID: PMC7803339 DOI: 10.1212/nxg.0000000000000534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/25/2020] [Indexed: 11/15/2022]
Abstract
Objective To report the identification of 2 new homozygous recessive mutations in the synaptotagmin 2 (SYT2) gene as the genetic cause of severe and early presynaptic forms of congenital myasthenic syndromes (CMSs). Methods Next-generation sequencing identified new homozygous intronic and frameshift mutations in the SYT2 gene as a likely cause of presynaptic CMS. We describe the clinical and electromyographic patient phenotypes, perform ex vivo splicing analyses to characterize the effect of the intronic mutation on exon splicing, and analyze the functional impact of this variation at the neuromuscular junction (NMJ). Results The 2 infants presented a similar clinical phenotype evoking first a congenital myopathy characterized by muscle weakness and hypotonia. Next-generation sequencing allowed to the identification of 1 homozygous intronic mutation c.465+1G>A in patient 1 and another homozygous frameshift mutation c.328_331dup in patient 2, located respectively in the 5' splice donor site of SYT2 intron 4 and in exon 3. Functional studies of the intronic mutation validated the abolition of the splice donor site of exon 4 leading to its skipping. In-frame skipping of exon 4 that encodes part of the C2A calcium-binding domain of SYT2 is associated with a loss-of-function effect resulting in a decrease of neurotransmitter release and severe pre- and postsynaptic NMJ defects. Conclusions This study identifies new homozygous recessive SYT2 mutations as the underlying cause of severe and early presynaptic form of CMS expanding the genetic spectrum of recessive SYT2-related CMS associated with defects in neurotransmitter release.
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Affiliation(s)
- Stéphanie Bauché
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Alain Sureau
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Damien Sternberg
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - John Rendu
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Céline Buon
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Julien Messéant
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Myriam Boëx
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Denis Furling
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Julien Fauré
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Xénia Latypova
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Antoinette Bernabe Gelot
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Michèle Mayer
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Pierre Mary
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Sandra Whalen
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Emmanuel Fournier
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Isabelle Cloix
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Ganaelle Remerand
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Fanny Laffargue
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Marie-Christine Nougues
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Bruno Eymard
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Arnaud Isapof
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
| | - Laure Strochlic
- Sorbonne Université, INSERM, UMRS974, Centre de Recherche en Myologie, Hôpital de la Pitié-Salpêtrière, Paris, (S.B., A.S., C. B., J.M., M.B., D.F., E. F., B.F., B.E., A.I., L.S.); CHU APHP (D.S., J.R., J.F., X.L., A.B.G., M.M., P.M., S.W., E.F., I.C., G.R., F.L., M.C.N., B.F., B.E., A.I.); Aix-Marseille University, INSERM, INMED, Campus de Luminy, Marseille, France (A.B.G.); UFR Cardiogénétique et Myogénétique, Hôpital de la Pitié-Salpêtrière, APHP, Paris (D.S.); UF de génétique clinique, CRMR Anomalies du développement et syndromes malformatifs, APHP, Hôpital Armand Trousseau, Paris, France (S.W.); Université de Grenoble Alpes, INSERM, CHU Grenoble Alpes, GIN (J.R., J.F., X.L.); CHU Clermont Ferrand (I.C., G.R., F.L.); and Reference Centre for Neuromuscular Pathologies "Nord/Est/Ile-de France" Paris (A.B.G., M.M., P.M., S.W., M.C.N., B.F., B.E., A.I.)
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Yi XX, Li JY, Tang ZZ, Jiang S, Liu YH, Deng JG, Gao CH. Marinoid J, a phenylglycoside from Avicennia marina fruit, ameliorates cognitive impairment in rat vascular dementia: a quantitative iTRAQ proteomic study. PHARMACEUTICAL BIOLOGY 2020; 58:1211-1220. [PMID: 33280468 PMCID: PMC7723022 DOI: 10.1080/13880209.2020.1837187] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 04/11/2020] [Accepted: 10/09/2020] [Indexed: 06/12/2023]
Abstract
CONTEXT Fruit of Avicennia marina (Forsk.) Vierh. (Acanthaceae) is used as a Chinese herb. Studies have found that it contains marinoid J, a novel phenylethanoid glycoside (PG) compound, but its neuroprotective functions are largely unknown. OBJECTIVE This study evaluated the effects of marinoid J on vascular dementia (VD) and determined its potential mechanisms of action. MATERIALS AND METHODS The VD model was established by the ligation of the bilateral common carotid artery in Sprague-Dawley rats, who received daily intragastrically administration of saline, marinoid J (125 or 500 mg/kg body weight/d), or oxiracetam (250 mg/kg body weight/d) for 14 days (20 rats in each group). The Morris water maze (MWM) was used to evaluate cognitive performance. The hippocampus was subjected to histological and proteomic analyses. RESULTS Marinoid J shortened the escape latency of VD rats (31.07 ± 3.74 s, p < 0.05). It also decreased malondialdehyde (MDA) (27.53%) and nitric oxide (NO) (20.41%) while increasing superoxide dismutase (SOD) (11.26%) and glutathione peroxidase (GSH-Px) (20.38%) content in hippocampus tissues. Proteomic analysis revealed 45 differentially expressed proteins (DEPs) in marinoid J-treated VD rats, which included angiotensin-converting enzyme (ACE), keratin 18 (KRT18), cluster of differentiation 34 (CD34), and synaptotagmin II (SYT2). CONCLUSIONS Marinoid J played a role in protecting hippocampal neurons by regulating a set of proteins that influence oxidative stress and apoptosis, this effect may thereby alleviate the symptoms of VD rats. Thus, pharmacological manipulation of marinoid J may offer a novel opportunity for VD treatment.
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Affiliation(s)
- Xiang-xi Yi
- Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, China
- Faculty of Pharmacy, Guangxi University of Chinese Medicine, Guangxi, China
| | - Jia-yi Li
- Faculty of Pharmacy, Guangxi University of Chinese Medicine, Guangxi, China
| | - Zhen-zhou Tang
- Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, China
| | - Shu Jiang
- Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, China
| | - Yong-hong Liu
- Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, China
| | - Jia-gang Deng
- Faculty of Pharmacy, Guangxi University of Chinese Medicine, Guangxi, China
| | - Cheng-hai Gao
- Institute of Marine Drugs, Guangxi University of Chinese Medicine, Guangxi, China
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Blumer R, Streicher J, Carrero-Rojas G, Calvo PM, de la Cruz RR, Pastor AM. Palisade Endings Have an Exocytotic Machinery But Lack Acetylcholine Receptors and Distinct Acetylcholinesterase Activity. Invest Ophthalmol Vis Sci 2020; 61:31. [PMID: 33369640 PMCID: PMC7774060 DOI: 10.1167/iovs.61.14.31] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this work was to test whether palisade endings express structural and molecular features of exocytotic machinery, and are associated with acetylcholine receptors, and enzymes for neurotransmitter breakdown. Methods Extraocular rectus muscles from six cats were studied. Whole-mount preparations of extraocular muscles (EOMs) were immunolabeled with markers for exocytotic proteins, including synaptosomal-associated protein of 25 kDa (SNAP25), syntaxin, synaptobrevin, synaptotagmin, and complexin. Acetylcholine receptors (AChRs) were visualized with α-bungarotoxin and with an antibody against AChRs, and acetylcholinesterase (AChE) was tagged with anti-AChE. Molecular features of multicolor labeled palisade endings were analyzed in the confocal scanning microscope, and their ultrastructural features were revealed in the transmission electron microscope. Results All palisade endings expressed the exocytotic proteins SNAP25, syntaxin, synaptobrevin, synaptotagmin, and complexin. At the ultrastructural level, vesicles docked at the plasma membrane of terminal varicosities of palisade endings. No AChRs were associated with palisade endings as demonstrated by the absence of α-bungarotoxin and anti-AChR binding. AChE, the degradative enzyme for acetylcholine exhibited low, if any, activity in palisade endings. Axonal tracking showed that axons with multiple en grappe motor terminals were in continuity with palisade endings. Conclusions This study demonstrates that palisade endings exhibit structural and molecular characteristics of exocytotic machinery, suggesting neurotransmitter release. However, AChRs were not associated with palisade endings, so there is no binding site for acetylcholine, and, due to low/absent AChE activity, insufficient neurotransmitter removal. Thus, the present findings indicate that palisade endings belong to an effector system that is very different from that found in other skeletal muscles.
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Affiliation(s)
- Roland Blumer
- Center of Anatomy and Cell Biology, MIC, Medical University Vienna, Vienna, Austria
| | - Johannes Streicher
- Department of Anatomy and Biomechanics, Division of Anatomy and Developmental Biology, Karl Landsteiner University of Health Science, Krems an der Donau, Austria
| | - Génova Carrero-Rojas
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Paula M Calvo
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Rosa R de la Cruz
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Angel M Pastor
- Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
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38
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Melland H, Carr EM, Gordon SL. Disorders of synaptic vesicle fusion machinery. J Neurochem 2020; 157:130-164. [PMID: 32916768 DOI: 10.1111/jnc.15181] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/20/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022]
Abstract
The revolution in genetic technology has ushered in a new age for our understanding of the underlying causes of neurodevelopmental, neuromuscular and neurodegenerative disorders, revealing that the presynaptic machinery governing synaptic vesicle fusion is compromised in many of these neurological disorders. This builds upon decades of research showing that disturbance to neurotransmitter release via toxins can cause acute neurological dysfunction. In this review, we focus on disorders of synaptic vesicle fusion caused either by toxic insult to the presynapse or alterations to genes encoding the key proteins that control and regulate fusion: the SNARE proteins (synaptobrevin, syntaxin-1 and SNAP-25), Munc18, Munc13, synaptotagmin, complexin, CSPα, α-synuclein, PRRT2 and tomosyn. We discuss the roles of these proteins and the cellular and molecular mechanisms underpinning neurological deficits in these disorders.
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Affiliation(s)
- Holly Melland
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
| | - Elysa M Carr
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, Melbourne Dementia Research Centre, The University of Melbourne, Melbourne, Vic., Australia
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39
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Zhou M, Melin MD, Xu W, Südhof TC. Dysfunction of parvalbumin neurons in the cerebellar nuclei produces an action tremor. J Clin Invest 2020; 130:5142-5156. [PMID: 32634124 PMCID: PMC7524475 DOI: 10.1172/jci135802] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/24/2020] [Indexed: 12/16/2022] Open
Abstract
Essential tremor is a common brain disorder affecting millions of people, yet the neuronal mechanisms underlying this prevalent disease remain elusive. Here, we showed that conditional deletion of synaptotagmin-2, the fastest Ca2+ sensor for synaptic neurotransmitter release, from parvalbumin neurons in mice caused an action tremor syndrome resembling the core symptom of essential tremor patients. Combining brain region-specific and cell type-specific genetic manipulation methods, we found that deletion of synaptotagmin-2 from excitatory parvalbumin-positive neurons in cerebellar nuclei was sufficient to generate an action tremor. The synaptotagmin-2 deletion converted synchronous into asynchronous neurotransmitter release in projections from cerebellar nuclei neurons onto gigantocellular reticular nucleus neurons, which might produce an action tremor by causing signal oscillations during movement. The tremor was rescued by completely blocking synaptic transmission with tetanus toxin in cerebellar nuclei, which also reversed the tremor phenotype in the traditional harmaline-induced essential tremor model. Using a promising animal model for action tremor, our results thus characterized a synaptic circuit mechanism that may underlie the prevalent essential tremor disorder.
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Affiliation(s)
- Mu Zhou
- Department of Molecular and Cellular Physiology and
| | | | - Wei Xu
- Department of Molecular and Cellular Physiology and
| | - Thomas C. Südhof
- Department of Molecular and Cellular Physiology and
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, USA
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Donkervoort S, Mohassel P, Laugwitz L, Zaki MS, Kamsteeg EJ, Maroofian R, Chao KR, Verschuuren-Bemelmans CC, Horber V, Fock AJM, McCarty RM, Jain MS, Biancavilla V, McMacken G, Nalls M, Voermans NC, Elbendary HM, Snyder M, Cai C, Lehky TJ, Stanley V, Iannaccone ST, Foley AR, Lochmüller H, Gleeson J, Houlden H, Haack TB, Horvath R, Bönnemann CG. Biallelic loss of function variants in SYT2 cause a treatable congenital onset presynaptic myasthenic syndrome. Am J Med Genet A 2020; 182:2272-2283. [PMID: 32776697 DOI: 10.1002/ajmg.a.61765] [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: 04/19/2020] [Revised: 05/25/2020] [Accepted: 06/13/2020] [Indexed: 12/15/2022]
Abstract
Synaptotagmins are integral synaptic vesicle membrane proteins that function as calcium sensors and regulate neurotransmitter release at the presynaptic nerve terminal. Synaptotagmin-2 (SYT2), is the major isoform expressed at the neuromuscular junction. Recently, dominant missense variants in SYT2 have been reported as a rare cause of distal motor neuropathy and myasthenic syndrome, manifesting with stable or slowly progressive distal weakness of variable severity along with presynaptic NMJ impairment. These variants are thought to have a dominant-negative effect on synaptic vesicle exocytosis, although the precise pathomechanism remains to be elucidated. Here we report seven patients of five families, with biallelic loss of function variants in SYT2, clinically manifesting with a remarkably consistent phenotype of severe congenital onset hypotonia and weakness, with variable degrees of respiratory involvement. Electrodiagnostic findings were consistent with a presynaptic congenital myasthenic syndrome (CMS) in some. Treatment with an acetylcholinesterase inhibitor pursued in three patients showed clinical improvement with increased strength and function. This series further establishes SYT2 as a CMS-disease gene and expands its clinical and genetic spectrum to include recessive loss-of-function variants, manifesting as a severe congenital onset presynaptic CMS with potential treatment implications.
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Affiliation(s)
- Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Payam Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Lucia Laugwitz
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,Department of Paediatric Neurology, University Children's Hospital, Tübingen, Germany
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London Institute of Neurology, London, UK
| | - Katherine R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - Veronka Horber
- Department of Paediatric Neurology, University Children's Hospital, Tübingen, Germany
| | - Annemarie J M Fock
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Riley M McCarty
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Minal S Jain
- Rehabilitation Medicine Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Victoria Biancavilla
- Rehabilitation Medicine Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Grace McMacken
- Department of Neurosciences, Royal Victoria Hospital, Belfast, UK
| | - Matthew Nalls
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Nicol C Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Hasnaa M Elbendary
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Molly Snyder
- Department of Neurology, Children's Health, Dallas, Texas, USA
| | - Chunyu Cai
- Department of Pathology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Tanya J Lehky
- EMG Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Valentina Stanley
- Laboratory for Pediatric Brain Disease, Howard Hughes Medical Institute, University of California, San Diego, California, USA.,Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, California, USA
| | - Susan T Iannaccone
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas, USA
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Hanns Lochmüller
- Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Joseph Gleeson
- Laboratory for Pediatric Brain Disease, Howard Hughes Medical Institute, University of California, San Diego, California, USA.,Rady Children's Institute for Genomic Medicine, Rady Children's Hospital, San Diego, California, USA
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London Institute of Neurology, London, UK
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Wolfes AC, Dean C. The diversity of synaptotagmin isoforms. Curr Opin Neurobiol 2020; 63:198-209. [PMID: 32663762 DOI: 10.1016/j.conb.2020.04.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/07/2020] [Accepted: 04/10/2020] [Indexed: 12/20/2022]
Abstract
The synaptotagmin family of molecules is known for regulating calcium-dependent membrane fusion events. Mice and humans express 17 synaptotagmin isoforms, where most studies have focused on isoforms 1, 2, and 7, which are involved in synaptic vesicle exocytosis. Recent work has highlighted how brain function relies on additional isoforms, with roles in postsynaptic receptor endocytosis, vesicle trafficking, membrane repair, synaptic plasticity, and protection against neurodegeneration, for example, in addition to the traditional concept of synaptotagmin-mediated neurotransmitter release - in neurons as well as glia, and at different timepoints. In fact, it is not uncommon for the same isoform to feature several splice isoforms, form homo- and heterodimers, and function in different subcellular locations and cell types. This review aims to highlight the diversity of synaptotagmins, offers a concise summary of key findings on all isoforms, and discusses different ways of grouping these.
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Affiliation(s)
- Anne C Wolfes
- Department of Brain Sciences, Division of Neuroscience, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK; UK Dementia Research Institute at Imperial College, London, UK
| | - Camin Dean
- German Center for Neurodegenerative Diseases, Charité University of Medicine - Berlin, 10117 Berlin, Germany.
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Verhage M, Sørensen JB. SNAREopathies: Diversity in Mechanisms and Symptoms. Neuron 2020; 107:22-37. [PMID: 32559416 DOI: 10.1016/j.neuron.2020.05.036] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/29/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022]
Abstract
Neuronal SNAREs and their key regulators together drive synaptic vesicle exocytosis and synaptic transmission as a single integrated membrane fusion machine. Human pathogenic mutations have now been reported for all eight core components, but patients are diagnosed with very different neurodevelopmental syndromes. We propose to unify these syndromes, based on etiology and mechanism, as "SNAREopathies." Here, we review the strikingly diverse clinical phenomenology and disease severity and the also remarkably diverse genetic mechanisms. We argue that disease severity generally scales with functional redundancy and, conversely, that the large effect of mutations in some SNARE genes is the price paid for extensive integration and exceptional specialization. Finally, we discuss how subtle differences in components being rate limiting in different types of neurons helps to explain the main symptoms.
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Affiliation(s)
- Matthijs Verhage
- Department of Functional Genomics, Vrije Universiteit (VU) Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands; Department of Clinical Genetics, UMC Amsterdam, De Boelelaan 1085, Amsterdam 1081 HV, the Netherlands.
| | - Jakob B Sørensen
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark.
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43
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Guan Z, Quiñones-Frías MC, Akbergenova Y, Littleton JT. Drosophila Synaptotagmin 7 negatively regulates synaptic vesicle release and replenishment in a dosage-dependent manner. eLife 2020; 9:e55443. [PMID: 32343229 PMCID: PMC7224696 DOI: 10.7554/elife.55443] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 04/28/2020] [Indexed: 01/03/2023] Open
Abstract
Synchronous neurotransmitter release is triggered by Ca2+ binding to the synaptic vesicle protein Synaptotagmin 1, while asynchronous fusion and short-term facilitation is hypothesized to be mediated by plasma membrane-localized Synaptotagmin 7 (SYT7). We generated mutations in Drosophila Syt7 to determine if it plays a conserved role as the Ca2+ sensor for these processes. Electrophysiology and quantal imaging revealed evoked release was elevated 2-fold. Syt7 mutants also had a larger pool of readily-releasable vesicles, faster recovery following stimulation, and intact facilitation. Syt1/Syt7 double mutants displayed more release than Syt1 mutants alone, indicating SYT7 does not mediate the residual asynchronous release remaining in the absence of SYT1. SYT7 localizes to an internal membrane tubular network within the peri-active zone, but does not enrich at active zones. These findings indicate the two Ca2+ sensor model of SYT1 and SYT7 mediating all phases of neurotransmitter release and facilitation is not applicable at Drosophila synapses.
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Affiliation(s)
- Zhuo Guan
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Monica C Quiñones-Frías
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Yulia Akbergenova
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
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44
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Schenke M, Schjeide BM, Püschel GP, Seeger B. Analysis of Motor Neurons Differentiated from Human Induced Pluripotent Stem Cells for the Use in Cell-Based Botulinum Neurotoxin Activity Assays. Toxins (Basel) 2020; 12:toxins12050276. [PMID: 32344847 PMCID: PMC7291138 DOI: 10.3390/toxins12050276] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/12/2020] [Accepted: 04/23/2020] [Indexed: 01/03/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) are potent neurotoxins produced by bacteria, which inhibit neurotransmitter release, specifically in their physiological target known as motor neurons (MNs). For the potency assessment of BoNTs produced for treatment in traditional and aesthetic medicine, the mouse lethality assay is still used by the majority of manufacturers, which is ethically questionable in terms of the 3Rs principle. In this study, MNs were differentiated from human induced pluripotent stem cells based on three published protocols. The resulting cell populations were analyzed for their MN yield and their suitability for the potency assessment of BoNTs. MNs produce specific gangliosides and synaptic proteins, which are bound by BoNTs in order to be taken up by receptor-mediated endocytosis, which is followed by cleavage of specific soluble N-ethylmaleimide-sensitive-factor attachment receptor (SNARE) proteins required for neurotransmitter release. The presence of receptors and substrates for all BoNT serotypes was demonstrated in MNs generated in vitro. In particular, the MN differentiation protocol based on Du et al. yielded high numbers of MNs in a short amount of time with high expression of BoNT receptors and targets. The resulting cells are more sensitive to BoNT/A1 than the commonly used neuroblastoma cell line SiMa. MNs are, therefore, an ideal tool for being combined with already established detection methods.
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Affiliation(s)
- Maren Schenke
- Institute for Food Toxicology, Department of Food Toxicology and Replacement/Complementary Methods to Animal Testing, University of Veterinary Medicine, 30173 Hannover, Germany;
| | - Brit-Maren Schjeide
- Institute of Nutritional Science, Department of Nutritional Biochemistry, University of Potsdam, 14558 Nuthetal, Germany; (B.-M.S.); (G.P.P.)
| | - Gerhard P. Püschel
- Institute of Nutritional Science, Department of Nutritional Biochemistry, University of Potsdam, 14558 Nuthetal, Germany; (B.-M.S.); (G.P.P.)
| | - Bettina Seeger
- Institute for Food Toxicology, Department of Food Toxicology and Replacement/Complementary Methods to Animal Testing, University of Veterinary Medicine, 30173 Hannover, Germany;
- Correspondence:
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Poulain B, Lemichez E, Popoff MR. Neuronal selectivity of botulinum neurotoxins. Toxicon 2020; 178:20-32. [PMID: 32094099 DOI: 10.1016/j.toxicon.2020.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 12/12/2022]
Abstract
Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis. BoNTs recognize a specific double receptor on neuronal cells consisting of gangliosides and synaptic vesicle protein, SV2 or synaptotagmin. Using cultured neuronal cells, BoNTs have been established blocking the release of a wide variety of neurotransmitters. However, BoNTs are more potent in motor-neurons than in the other neuronal cell types. In in vivo models, BoNT/A impairs the cholinergic neuronal transmission at the motor-neurons but also at neurons controlling secretions and smooth muscle neurons, and blocks several neuronal pathways including excitatory, inhibitory, and sensitive neurons. However, only a few reports investigated the neuronal selectivity of BoNTs in vivo. In the intestinal wall, BoNT/A and BoNT/B target mainly the cholinergic neurons and to a lower extent the other non-cholinergic neurons including serotonergic, glutamatergic, GABAergic, and VIP-neurons. The in vivo effects induced by BoNTs on the non-cholinergic neurons remain to be precisely investigated. We report here a literature review of the neuronal selectivity of BoNTs.
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Affiliation(s)
- Bernard Poulain
- Université de Strasbourg, CNRS, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
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TrkB Signaling Influences Gene Expression in Cortistatin-Expressing Interneurons. eNeuro 2020; 7:ENEURO.0310-19.2019. [PMID: 31941661 PMCID: PMC7031852 DOI: 10.1523/eneuro.0310-19.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/14/2019] [Accepted: 12/04/2019] [Indexed: 01/02/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) signals through its cognate receptor tropomyosin receptor kinase B (TrkB) to promote the function of several classes of inhibitory interneurons. We previously reported that loss of BDNF-TrkB signaling in cortistatin (Cort)-expressing interneurons leads to behavioral hyperactivity and spontaneous seizures in mice. We performed bulk RNA sequencing (RNA-seq) from the cortex of mice with disruption of BDNF-TrkB signaling in cortistatin interneurons, and identified differential expression of genes important for excitatory neuron function. Using translating ribosome affinity purification and RNA-seq, we define a molecular profile for Cort-expressing inhibitory neurons and subsequently compare the translatome of normal and TrkB-depleted Cort neurons, revealing alterations in calcium signaling and axon development. Several of the genes enriched in Cort neurons and differentially expressed in TrkB-depleted neurons are also implicated in autism and epilepsy. Our findings highlight TrkB-dependent molecular pathways as critical for the maturation of inhibitory interneurons and support the hypothesis that loss of BDNF signaling in Cort interneurons leads to altered excitatory/inhibitory balance.
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Park J, Park SJ, Kim S. Inositol polyphosphate multikinase deficiency leads to aberrant induction of synaptotagmin-2 in the forebrain. Mol Brain 2019; 12:58. [PMID: 31221192 PMCID: PMC6584979 DOI: 10.1186/s13041-019-0480-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/13/2019] [Indexed: 12/30/2022] Open
Abstract
Inositol polyphosphate multikinase (IPMK), the key enzyme responsible for the synthesis of higher inositol polyphosphates and phosphatidylinositol 3, 4, 5-trisphosphate, is known to mediate various biological events, such as cellular growth and metabolism. Conditional deletion of IPMK in excitatory neurons of the mouse postnatal forebrain results in enhanced extinction of fear memory accompanied by activation of p85 S6 kinase 1 signaling in the amygdala; it also facilitates hippocampal long-term potentiation. However, the molecular changes triggered by IPMK deletion in the brain have not been fully elucidated. In the present study, we investigated gene expression changes in the hippocampal region of IPMK conditional knockout (cKO) mice by performing genome-wide transcriptome analyses. Here we show that expression of synaptotagmin 2 (Syt2), a synaptic vesicle protein essential for Ca2+-dependent neurotransmitter release, is robustly upregulated in the forebrain of IPMKcKO mice. Compared to wild-type mice, in which weak Syt2 expression was detected in the forebrain, IPMKcKO mice showed marked increases in both Syt2 mRNA and protein expression in the hippocampus as well as the amygdala. Collectively, our results suggest a physiological role for IPMK in regulating expression of Syt2, providing a potential underlying molecular mechanism to explain IPMK-mediated neural functions.
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Affiliation(s)
- Jina Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Seung Ju Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea. .,KAIST Institute for the BioCentury, KAIST, Daejeon, 34141, South Korea.
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Ablation of All Synaptobrevin vSNAREs Blocks Evoked But Not Spontaneous Neurotransmitter Release at Neuromuscular Synapses. J Neurosci 2019; 39:6049-6066. [PMID: 31160536 DOI: 10.1523/jneurosci.0403-19.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/26/2019] [Accepted: 05/13/2019] [Indexed: 01/16/2023] Open
Abstract
Synaptic transmission occurs when an action potential triggers neurotransmitter release via the fusion of synaptic vesicles with the presynaptic membrane, driven by the formation of SNARE complexes composed of the vesicular (v)-SNARE synaptobrevin and the target (t)-SNAREs Snap-25 and syntaxin-1. Neurotransmitters are also released spontaneously, independent of an action potential, through the fusion of synaptic vesicles with the presynaptic membrane. The major neuronal vSNAREs, synaptobrevin-1 and synaptobrevin-2, are expressed at the developing neuromuscular junction (NMJ) in mice, but their specific roles in NMJ formation and function remain unclear. Here, we examine the NMJs in mutant mouse embryos lacking either synaptobrevin 1 (Syb1lew/lew ) or synaptobrevin 2 (Syb2 -/-), and those lacking both (Syb1lew/lewSyb2 -/-). We found that, compared with controls: (1) the number and size of NMJs was markedly increased in Syb2 -/- and Syb1lew/lewSyb2 -/- mice, but not in Syb1lew/lew mice; (2) synaptic vesicle density was markedly reduced in Syb1lew/lewSyb2 -/- NMJs; and (3) evoked neurotransmission was markedly reduced in Syb2 -/- NMJs and completely abolished in Syb1lew/lewSyb2 -/- NMJs. Surprisingly, however, spontaneous neurotransmission persists in the absence of both Syb1 and Syb2. Furthermore, spontaneous neurotransmission remains constant in Syb1lew/lewSyb2 -/- NMJs despite changing Ca2+ levels. These findings reveal an overlapping role for Syb1 and Syb2 (with Syb2 being dominant) in developing NMJs in mice. Moreover, because spontaneous release becomes Ca2+-insensitive in Syb1lew/lewSyb2 -/- NMJs, our findings suggest that synaptobrevin-based SNARE complexes play a critical role in conferring Ca2+ sensitivity during spontaneous release.SIGNIFICANCE STATEMENT Neurotransmitters can be released at synapses with (evoked) or without (spontaneous) the influence of action potentials. Whereas evoked neurotransmission requires Ca2+ influx, those underlying the spontaneous neurotransmission may occur with or without Ca2+ Our findings show that, in the absence neuronal vSNARE synaptobrevin-1 and synaptobrevin-2, evoked neurotransmission is completely abolished; however, spontaneous synaptic transmission not only persists but even increased. Furthermore, spontaneous synaptic transmission that is normally highly Ca2+-sensitive became Ca2+-independent upon deletion of vSNARE synaptobrevin-1 and synaptobrevin-2. These findings reveal distinct mechanisms for evoked and spontaneous neurotransmitter release. Moreover, these findings suggest that synaptobrevin-based SNARE complexes play critical roles in conferring Ca2+ sensitivity during spontaneous neurotransmission at developing neuromuscular synapses in mice.
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Cameron S, Lopez A, Glabman R, Abrams E, Johnson S, Field C, Gulland FMD, Buckmaster PS. Proportional loss of parvalbumin-immunoreactive synaptic boutons and granule cells from the hippocampus of sea lions with temporal lobe epilepsy. J Comp Neurol 2019; 527:2341-2355. [PMID: 30861128 DOI: 10.1002/cne.24680] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/18/2019] [Accepted: 03/02/2019] [Indexed: 01/10/2023]
Abstract
One in 26 people develop epilepsy and in these temporal lobe epilepsy (TLE) is common. Many patients display a pattern of neuron loss called hippocampal sclerosis. Seizures usually start in the hippocampus but underlying mechanisms remain unclear. One possibility is insufficient inhibition of dentate granule cells. Normally parvalbumin-immunoreactive (PV) interneurons strongly inhibit granule cells. Humans with TLE display loss of PV interneurons in the dentate gyrus but questions persist. To address this, we evaluated PV interneuron and bouton numbers in California sea lions (Zalophus californianus) that naturally develop TLE after exposure to domoic acid, a neurotoxin that enters the marine food chain during harmful algal blooms. Sclerotic hippocampi were identified by the loss of Nissl-stained hilar neurons. Stereological methods were used to estimate the number of granule cells and PV interneurons per dentate gyrus. Sclerotic hippocampi contained fewer granule cells, fewer PV interneurons, and fewer PV synaptic boutons, and the ratio of granule cells to PV interneurons was higher than in controls. To test whether fewer boutons was attributable to loss versus reduced immunoreactivity, expression of synaptotagmin-2 (syt2) was evaluated. Syt2 is also expressed in boutons of PV interneurons. Sclerotic hippocampi displayed proportional losses of syt2-immunoreactive boutons, PV boutons, and granule cells. There was no significant difference in the average numbers of PV- or syt2-positive boutons per granule cell between control and sclerotic hippocampi. These findings do not address functionality of surviving synapses but suggest reduced granule cell inhibition in TLE is not attributable to anatomical loss of PV boutons.
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Affiliation(s)
- Starr Cameron
- Department of Comparative Medicine, Stanford University, Stanford, California
| | - Ariana Lopez
- Department of Comparative Medicine, Stanford University, Stanford, California.,College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Raisa Glabman
- Department of Comparative Medicine, Stanford University, Stanford, California.,School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Emily Abrams
- Department of Comparative Medicine, Stanford University, Stanford, California
| | | | - Cara Field
- The Marine Mammal Center, Sausalito, California
| | | | - Paul S Buckmaster
- Department of Comparative Medicine, Stanford University, Stanford, California.,Department of Neurology & Neurological Sciences, Stanford University, Stanford, California
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Nicolau S, Milone M. The Electrophysiology of Presynaptic Congenital Myasthenic Syndromes With and Without Facilitation: From Electrodiagnostic Findings to Molecular Mechanisms. Front Neurol 2019; 10:257. [PMID: 30941097 PMCID: PMC6433874 DOI: 10.3389/fneur.2019.00257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 02/26/2019] [Indexed: 11/13/2022] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of inherited disorders of neuromuscular transmission most commonly presenting with early onset fatigable weakness, ptosis, and ophthalmoparesis. CMS are classified according to the localization of the causative molecular defect. CMS with presynaptic dysfunction can be caused by mutations in several different genes, including those involved in acetylcholine synthesis, its packaging into synaptic vesicles, vesicle docking, and release from the presynaptic nerve terminal and neuromuscular junction development and maintenance. Electrodiagnostic testing is key in distinguishing CMS from other neuromuscular disorders with similar clinical features as well as for revealing features pointing to a specific molecular diagnosis. A decremental response on low-frequency repetitive nerve stimulation (RNS) is present in most presynaptic CMS. In CMS with deficits in acetylcholine resynthesis however, a decrement may only appear after conditioning with exercise or high-frequency RNS and characteristically displays a slow recovery. Facilitation occurs in CMS caused by mutations in VAMP1, UNC13A, SYT2, AGRN, LAMA5. By contrast, facilitation is absent in the other presynaptic CMS described to date. An understanding of the underlying molecular mechanisms therefore assists the interpretation of electrodiagnostic findings in patients with suspected CMS.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
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