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Thome C, Janssen JM, Karabulut S, Acuna C, D’Este E, Soyka SJ, Baum K, Bock M, Lehmann N, Roos J, Stevens NA, Hasegawa M, Ganea DA, Benoit CM, Gründemann J, Min L, Bird KM, Schultz C, Bennett V, Jenkins PM, Engelhardt M. Live imaging of excitable axonal microdomains in ankyrin-G-GFP mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.02.01.525891. [PMID: 38948770 PMCID: PMC11212890 DOI: 10.1101/2023.02.01.525891] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
The axon initial segment (AIS) constitutes not only the site of action potential initiation, but also a hub for activity-dependent modulation of output generation. Recent studies shedding light on AIS function used predominantly post-hoc approaches since no robust murine in vivo live reporters exist. Here, we introduce a reporter line in which the AIS is intrinsically labeled by an ankyrin-G-GFP fusion protein activated by Cre recombinase, tagging the native Ank3 gene. Using confocal, superresolution, and two-photon microscopy as well as whole-cell patch-clamp recordings in vitro, ex vivo, and in vivo, we confirm that the subcellular scaffold of the AIS and electrophysiological parameters of labeled cells remain unchanged. We further uncover rapid AIS remodeling following increased network activity in this model system, as well as highly reproducible in vivo labeling of AIS over weeks. This novel reporter line allows longitudinal studies of AIS modulation and plasticity in vivo in real-time and thus provides a unique approach to study subcellular plasticity in a broad range of applications.
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Affiliation(s)
- Christian Thome
- Institute of Anatomy and Cell Biology, Johannes Kepler University, 4020 Linz, Austria
- Clinical Research Institute of Neuroscience, Johannes Kepler University, 4020 Linz, Austria
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jan Maximilian Janssen
- Institute of Anatomy and Cell Biology, Johannes Kepler University, 4020 Linz, Austria
- Clinical Research Institute of Neuroscience, Johannes Kepler University, 4020 Linz, Austria
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Seda Karabulut
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Claudio Acuna
- Chica and Heinz Schaller Research Group, Institute of Anatomy and Cell Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Elisa D’Este
- Optical Microscopy Facility, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Stella J. Soyka
- Institute of Anatomy and Cell Biology, Dept. of Functional Neuroanatomy, Heidelberg University, 69120 Heidelberg, Germany
| | - Konrad Baum
- Institute of Anatomy and Cell Biology, Johannes Kepler University, 4020 Linz, Austria
- Clinical Research Institute of Neuroscience, Johannes Kepler University, 4020 Linz, Austria
| | - Michael Bock
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Nadja Lehmann
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Johannes Roos
- Institute of Anatomy and Cell Biology, Johannes Kepler University, 4020 Linz, Austria
- Clinical Research Institute of Neuroscience, Johannes Kepler University, 4020 Linz, Austria
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Nikolas A. Stevens
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Masashi Hasegawa
- German Center for Neurodegenerative Disease (DZNE), Neural Circuit Computations, 53127 Bonn, Germany
| | - Dan A. Ganea
- University of Basel, Department of Biomedicine, 4031 Basel, Switzerland
| | - Chloé M. Benoit
- German Center for Neurodegenerative Disease (DZNE), Neural Circuit Computations, 53127 Bonn, Germany
- University of Basel, Department of Biomedicine, 4031 Basel, Switzerland
| | - Jan Gründemann
- German Center for Neurodegenerative Disease (DZNE), Neural Circuit Computations, 53127 Bonn, Germany
- University of Basel, Department of Biomedicine, 4031 Basel, Switzerland
| | - Lia Min
- Departments of Pharmacology and Psychiatry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Kalynn M. Bird
- Departments of Pharmacology and Psychiatry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Christian Schultz
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Vann Bennett
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Paul M. Jenkins
- Departments of Pharmacology and Psychiatry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Johannes Kepler University, 4020 Linz, Austria
- Clinical Research Institute of Neuroscience, Johannes Kepler University, 4020 Linz, Austria
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
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Wang Y, Chen Y, Chen L, Herron BJ, Chen XY, Wolpaw JR. Motor learning changes the axon initial segment of the spinal motoneuron. J Physiol 2024; 602:2107-2126. [PMID: 38568869 PMCID: PMC11196014 DOI: 10.1113/jp283875] [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: 02/26/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024] Open
Abstract
We are studying the mechanisms of H-reflex operant conditioning, a simple form of learning. Modelling studies in the literature and our previous data suggested that changes in the axon initial segment (AIS) might contribute. To explore this, we used blinded quantitative histological and immunohistochemical methods to study in adult rats the impact of H-reflex conditioning on the AIS of the spinal motoneuron that produces the reflex. Successful, but not unsuccessful, H-reflex up-conditioning was associated with greater AIS length and distance from soma; greater length correlated with greater H-reflex increase. Modelling studies in the literature suggest that these increases may increase motoneuron excitability, supporting the hypothesis that they may contribute to H-reflex increase. Up-conditioning did not affect AIS ankyrin G (AnkG) immunoreactivity (IR), p-p38 protein kinase IR, or GABAergic terminals. Successful, but not unsuccessful, H-reflex down-conditioning was associated with more GABAergic terminals on the AIS, weaker AnkG-IR, and stronger p-p38-IR. More GABAergic terminals and weaker AnkG-IR correlated with greater H-reflex decrease. These changes might potentially contribute to the positive shift in motoneuron firing threshold underlying H-reflex decrease; they are consistent with modelling suggesting that sodium channel change may be responsible. H-reflex down-conditioning did not affect AIS dimensions. This evidence that AIS plasticity is associated with and might contribute to H-reflex conditioning adds to evidence that motor learning involves both spinal and brain plasticity, and both neuronal and synaptic plasticity. AIS properties of spinal motoneurons are likely to reflect the combined influence of all the motor skills that share these motoneurons. KEY POINTS: Neuronal action potentials normally begin in the axon initial segment (AIS). AIS plasticity affects neuronal excitability in development and disease. Whether it does so in learning is unknown. Operant conditioning of a spinal reflex, a simple learning model, changes the rat spinal motoneuron AIS. Successful, but not unsuccessful, H-reflex up-conditioning is associated with greater AIS length and distance from soma. Successful, but not unsuccessful, down-conditioning is associated with more AIS GABAergic terminals, less ankyrin G, and more p-p38 protein kinase. The associations between AIS plasticity and successful H-reflex conditioning are consistent with those between AIS plasticity and functional changes in development and disease, and with those predicted by modelling studies in the literature. Motor learning changes neurons and synapses in spinal cord and brain. Because spinal motoneurons are the final common pathway for behaviour, their AIS properties probably reflect the combined impact of all the behaviours that use these motoneurons.
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Affiliation(s)
- Yu Wang
- National Center for Adaptive Neurotechnologies, Albany Stratton VA Medical Center, 113 Holland Ave, Albany, NY 12208
| | - Yi Chen
- National Center for Adaptive Neurotechnologies, Albany Stratton VA Medical Center, 113 Holland Ave, Albany, NY 12208
| | - Lu Chen
- National Center for Adaptive Neurotechnologies, Albany Stratton VA Medical Center, 113 Holland Ave, Albany, NY 12208
| | - Bruce J. Herron
- Wadsworth Center, New York State Department of Health, 150 New Scotland Ave, Albany, NY 12208
- Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, New York
| | - Xiang Yang Chen
- National Center for Adaptive Neurotechnologies, Albany Stratton VA Medical Center, 113 Holland Ave, Albany, NY 12208
- Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, New York
| | - Jonathan R. Wolpaw
- National Center for Adaptive Neurotechnologies, Albany Stratton VA Medical Center, 113 Holland Ave, Albany, NY 12208
- Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, New York
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3
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Seignette K, Jamann N, Papale P, Terra H, Porneso RO, de Kraker L, van der Togt C, van der Aa M, Neering P, Ruimschotel E, Roelfsema PR, Montijn JS, Self MW, Kole MHP, Levelt CN. Experience shapes chandelier cell function and structure in the visual cortex. eLife 2024; 12:RP91153. [PMID: 38192196 PMCID: PMC10963032 DOI: 10.7554/elife.91153] [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] [Indexed: 01/10/2024] Open
Abstract
Detailed characterization of interneuron types in primary visual cortex (V1) has greatly contributed to understanding visual perception, yet the role of chandelier cells (ChCs) in visual processing remains poorly characterized. Using viral tracing we found that V1 ChCs predominantly receive monosynaptic input from local layer 5 pyramidal cells and higher-order cortical regions. Two-photon calcium imaging and convolutional neural network modeling revealed that ChCs are visually responsive but weakly selective for stimulus content. In mice running in a virtual tunnel, ChCs respond strongly to events known to elicit arousal, including locomotion and visuomotor mismatch. Repeated exposure of the mice to the virtual tunnel was accompanied by reduced visual responses of ChCs and structural plasticity of ChC boutons and axon initial segment length. Finally, ChCs only weakly inhibited pyramidal cells. These findings suggest that ChCs provide an arousal-related signal to layer 2/3 pyramidal cells that may modulate their activity and/or gate plasticity of their axon initial segments during behaviorally relevant events.
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Affiliation(s)
- Koen Seignette
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Nora Jamann
- Department of Axonal Signaling, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Department of Biology Cell Biology, Neurobiology and Biophysics, Faculty of Science, Utrecht UniversityUtrechtNetherlands
| | - Paolo Papale
- Department of Vision & Cognition, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Huub Terra
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Ralph O Porneso
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Leander de Kraker
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Chris van der Togt
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Department of Vision & Cognition, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Maaike van der Aa
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Paul Neering
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Department of Vision & Cognition, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Emma Ruimschotel
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Pieter R Roelfsema
- Department of Vision & Cognition, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Laboratory of Visual Brain Therapy, Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la VisionParisFrance
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, VU UniversityAmsterdamNetherlands
- Department of Psychiatry, Academic Medical Center, University of AmsterdamAmsterdamNetherlands
| | - Jorrit S Montijn
- Department of Cortical Structure & Function, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Matthew W Self
- Department of Vision & Cognition, Netherlands Institute for NeuroscienceAmsterdamNetherlands
| | - Maarten HP Kole
- Department of Axonal Signaling, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Department of Biology Cell Biology, Neurobiology and Biophysics, Faculty of Science, Utrecht UniversityUtrechtNetherlands
| | - Christiaan N Levelt
- Department of Molecular Visual Plasticity, Netherlands Institute for NeuroscienceAmsterdamNetherlands
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University AmsterdamAmsterdamNetherlands
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Harley P, Kerins C, Gatt A, Neves G, Riccio F, Machado CB, Cheesbrough A, R'Bibo L, Burrone J, Lieberam I. Aberrant axon initial segment plasticity and intrinsic excitability of ALS hiPSC motor neurons. Cell Rep 2023; 42:113509. [PMID: 38019651 DOI: 10.1016/j.celrep.2023.113509] [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: 05/04/2023] [Revised: 10/06/2023] [Accepted: 11/13/2023] [Indexed: 12/01/2023] Open
Abstract
Dysregulated neuronal excitability is a hallmark of amyotrophic lateral sclerosis (ALS). We sought to investigate how functional changes to the axon initial segment (AIS), the site of action potential generation, could impact neuronal excitability in ALS human induced pluripotent stem cell (hiPSC) motor neurons. We find that early TDP-43 and C9orf72 hiPSC motor neurons show an increase in the length of the AIS and impaired activity-dependent AIS plasticity that is linked to abnormal homeostatic regulation of neuronal activity and intrinsic hyperexcitability. In turn, these hyperactive neurons drive increased spontaneous myofiber contractions of in vitro hiPSC motor units. In contrast, late hiPSC and postmortem ALS motor neurons show AIS shortening, and hiPSC motor neurons progress to hypoexcitability. At a molecular level, aberrant expression of the AIS master scaffolding protein ankyrin-G and AIS-specific voltage-gated sodium channels mirror these dynamic changes in AIS function and excitability. Our results point toward the AIS as an important site of dysfunction in ALS motor neurons.
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Affiliation(s)
- Peter Harley
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK; UCL Queen Square Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, UCL, London, UK
| | - Caoimhe Kerins
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK; Centre for Craniofacial & Regenerative Biology, King's College London, London SE1 9RT, UK
| | - Ariana Gatt
- Queen Square Brain Bank, Department of Neurodegenerative Disease, Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Guilherme Neves
- Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK
| | - Federica Riccio
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK
| | - Carolina Barcellos Machado
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK
| | - Aimee Cheesbrough
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK
| | - Lea R'Bibo
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK
| | - Juan Burrone
- Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, Kings College London, London SE1 1UL, UK.
| | - Ivo Lieberam
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK; Centre for Developmental Neurobiology, Kings College London, London SE1 1UL, UK; MRC Centre for Neurodevelopmental Disorders, Kings College London, London SE1 1UL, UK.
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5
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Proddutur A, Nguyen S, Yeh CW, Gupta A, Santhakumar V. Reclusive chandeliers: Functional isolation of dentate axo-axonic cells after experimental status epilepticus. Prog Neurobiol 2023; 231:102542. [PMID: 37898313 PMCID: PMC10842856 DOI: 10.1016/j.pneurobio.2023.102542] [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: 05/02/2023] [Revised: 10/22/2023] [Accepted: 10/24/2023] [Indexed: 10/30/2023]
Abstract
Axo-axonic cells (AACs) provide specialized inhibition to the axon initial segment (AIS) of excitatory neurons and can regulate network output and synchrony. Although hippocampal dentate AACs are structurally altered in epilepsy, physiological analyses of dentate AACs are lacking. We demonstrate that parvalbumin neurons in the dentate molecular layer express PTHLH, an AAC marker, and exhibit morphology characteristic of AACs. Dentate AACs show high-frequency, non-adapting firing but lack persistent firing in the absence of input and have higher rheobase than basket cells suggesting that AACs can respond reliably to network activity. Early after pilocarpine-induced status epilepticus (SE), dentate AACs receive fewer spontaneous excitatory and inhibitory synaptic inputs and have significantly lower maximum firing frequency. Paired recordings and spatially localized optogenetic stimulation revealed that SE reduced the amplitude of unitary synaptic inputs from AACs to granule cells without altering reliability, short-term plasticity, or AIS GABA reversal potential. These changes compromised AAC-dependent shunting of granule cell firing in a multicompartmental model. These early post-SE changes in AAC physiology would limit their ability to receive and respond to input, undermining a critical brake on the dentate throughput during epileptogenesis.
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Affiliation(s)
- Archana Proddutur
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Susan Nguyen
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Chia-Wei Yeh
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Akshay Gupta
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA.
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Proddutur A, Nguyen S, Yeh CW, Gupta A, Santhakumar V. RECLUSIVE CHANDELIERS: FUNCTIONAL ISOLATION OF DENTATE AXO-AXONIC CELLS AFTER EXPERIMENTAL STATUS EPILEPTICUS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.01.560378. [PMID: 37873292 PMCID: PMC10592856 DOI: 10.1101/2023.10.01.560378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Axo-axonic cells (AACs) provide specialized inhibition to the axon initial segment (AIS) of excitatory neurons and can regulate network output and synchrony. Although hippocampal dentate AACs are structurally altered in epilepsy, physiological analyses of dentate AACs are lacking. We demonstrate that parvalbumin neurons in the dentate molecular layer express PTHLH, an AAC marker, and exhibit morphology characteristic of AACs. Dentate AACs show high-frequency, non-adapting firing but lack persistent firing in the absence of input and have higher rheobase than basket cells suggesting that AACs can respond reliably to network activity. Early after pilocarpine-induced status epilepticus (SE), dentate AACs receive fewer spontaneous excitatory and inhibitory synaptic inputs and have significantly lower maximum firing frequency. Paired recordings and spatially localized optogenetic stimulation revealed that SE reduced the amplitude of unitary synaptic inputs from AACs to granule cells without altering reliability, short-term plasticity, or AIS GABA reversal potential. These changes compromised AAC-dependent shunting of granule cell firing in a multicompartmental model. These early post-SE changes in AAC physiology would limit their ability to receive and respond to input, undermining a critical brake on the dentate throughput during epileptogenesis.
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Affiliation(s)
- Archana Proddutur
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Susan Nguyen
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Chia-Wei Yeh
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Akshay Gupta
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
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Puhl CJ, Wefelmeyer W, Burrone J. Cholinergic Stimulation Modulates the Functional Composition of CA3 Cell Types in the Hippocampus. J Neurosci 2023; 43:4972-4983. [PMID: 37277177 PMCID: PMC10324996 DOI: 10.1523/jneurosci.0966-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 03/03/2023] [Accepted: 03/07/2023] [Indexed: 06/07/2023] Open
Abstract
The functional heterogeneity of hippocampal CA3 pyramidal neurons has emerged as a key aspect of circuit function. Here, we explored the effects of long-term cholinergic activity on the functional heterogeneity of CA3 pyramidal neurons in organotypic slices obtained from male rat brains. Application of agonists to either AChRs generally, or mAChRs specifically, induced robust increases in network activity in the low-gamma range. Prolonged AChR stimulation for 48 h uncovered a population of hyperadapting CA3 pyramidal neurons that typically fired a single, early action potential in response to current injection. Although these neurons were present in control networks, their proportions were dramatically increased following long-term cholinergic activity. Characterized by the presence of a strong M-current, the hyperadaptation phenotype was abolished by acute application of either M-channel antagonists or the reapplication of AChR agonists. We conclude that long-term mAChR activation modulates the intrinsic excitability of a subset of CA3 pyramidal cells, uncovering a highly plastic cohort of neurons that are sensitive to chronic ACh modulation. Our findings provide evidence for the activity-dependent plasticity of functional heterogeneity in the hippocampus.SIGNIFICANCE STATEMENT The large heterogeneity of neuron types in the brain, each with its own specific functional properties, provides the rich cellular tapestry needed to account for the vast diversity of behaviors. By studying the functional properties of neurons in the hippocampus, a region of the brain involved in learning and memory, we find that exposure to the neuromodulator acetylcholine can alter the relative number of functionally defined neuron types. Our findings suggest that the heterogeneity of neurons in the brain is not a static feature but can be modified by the ongoing activity of the circuits to which they belong.
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Affiliation(s)
- Christopher Jon Puhl
- Centre for Developmental Neurobiology, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
| | - Winnie Wefelmeyer
- Centre for Developmental Neurobiology, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
| | - Juan Burrone
- Centre for Developmental Neurobiology, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Kings College London, New Hunts House, Guys Hospital Campus, London, SE1 1UL, United Kingdom
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8
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Lezmy J. How astrocytic ATP shapes neuronal activity and brain circuits. Curr Opin Neurobiol 2023; 79:102685. [PMID: 36746109 DOI: 10.1016/j.conb.2023.102685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 01/03/2023] [Accepted: 01/06/2023] [Indexed: 02/06/2023]
Abstract
Astrocytes play a key role in processing information at synapses, by controlling synapse formation, modulating synapse strength and terminating neurotransmitter action. They release ATP to shape brain activity but it is unclear how, as astrocyte processes contact many targets and ATP-mediated effects are diverse and numerous. Here, I review recent studies showing how astrocytic ATP modulates cellular mechanisms in nearby neurons and glia in the grey and white matter, how it affects signal transmission in these areas, and how it modulates behavioural outputs. I attempt to provide a flowchart of astrocytic ATP signalling, showing that it tends to inhibit neural circuits to match energy demands.
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Affiliation(s)
- Jonathan Lezmy
- Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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9
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Harley P, Paredes-Redondo A, Grenci G, Viasnoff V, Lin YY, Lieberam I. 3D Compartmentalised Human Pluripotent Stem Cell-derived Neuromuscular Co-cultures. Bio Protoc 2023; 13:e4624. [PMID: 36908638 PMCID: PMC9993083 DOI: 10.21769/bioprotoc.4624] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/26/2022] [Accepted: 01/30/2023] [Indexed: 03/07/2023] Open
Abstract
Human neuromuscular diseases represent a diverse group of disorders with unmet clinical need, ranging from muscular dystrophies, such as Duchenne muscular dystrophy (DMD), to neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS). In many of these conditions, axonal and neuromuscular synapse dysfunction have been implicated as crucial pathological events, highlighting the need for in vitro disease models that accurately recapitulate these aspects of human neuromuscular physiology. The protocol reported here describes the co-culture of neural spheroids composed of human pluripotent stem cell (PSC)-derived motor neurons and astrocytes, and human PSC-derived myofibers in 3D compartmentalised microdevices to generate functional human neuromuscular circuits in vitro. In this microphysiological model, motor axons project from a central nervous system (CNS)-like compartment along microchannels to innervate skeletal myofibers plated in a separate muscle compartment. This mimics the spatial organization of neuromuscular circuits in vivo. Optogenetics, particle image velocimetry (PIV) analysis, and immunocytochemistry are used to control, record, and quantify functional neuromuscular transmission, axonal outgrowth, and neuromuscular synapse number and morphology. This approach has been applied to study disease-specific phenotypes for DMD and ALS by incorporating patient-derived and CRISPR-corrected human PSC-derived motor neurons and skeletal myogenic progenitors into the model, as well as testing candidate drugs for rescuing pathological phenotypes. The main advantages of this approach are: i) its simple design; ii) the in vivo-like anatomical separation between CNS and peripheral muscle; and iii) the amenability of the approach to high power imaging. This opens up the possibility for carrying out live axonal transport and synaptic imaging assays in future studies, in addition to the applications reported in this study. Graphical abstract Graphical abstract abbreviations: Channelrhodopsin-2 (CHR2+), pluripotent stem cell (PSC), motor neurons (MNs), myofibers (MFs), neuromuscular junction (NMJ).
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Affiliation(s)
- Peter Harley
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK
- Centre for Developmental Neurobiology and MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London SE1 1UL, UK
| | - Amaia Paredes-Redondo
- Centre for Genomics and Child Health, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
- Centre for Predictive in vitro Model, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Gianluca Grenci
- Mechanobiology Institute, National University of Singapore, 5a Engineering Drive 1, 117411 Singapore
| | - Virgile Viasnoff
- Mechanobiology Institute, National University of Singapore, 5a Engineering Drive 1, 117411 Singapore
| | - Yung-Yao Lin
- Centre for Genomics and Child Health, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
- Centre for Predictive in vitro Model, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Ivo Lieberam
- Centre for Gene Therapy & Regenerative Medicine, Kings College London, London SE1 9RT, UK
- Centre for Developmental Neurobiology and MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London SE1 1UL, UK
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10
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Jungenitz T, Bird A, Engelhardt M, Jedlicka P, Schwarzacher SW, Deller T. Structural plasticity of the axon initial segment in rat hippocampal granule cells following high frequency stimulation and LTP induction. Front Neuroanat 2023; 17:1125623. [PMID: 37090138 PMCID: PMC10113456 DOI: 10.3389/fnana.2023.1125623] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/20/2023] [Indexed: 04/25/2023] Open
Abstract
The axon initial segment (AIS) is the site of action potential initiation and important for the integration of synaptic input. Length and localization of the AIS are dynamic, modulated by afferent activity and contribute to the homeostatic control of neuronal excitability. Synaptopodin is a plasticity-related protein expressed by the majority of telencephalic neurons. It is required for the formation of cisternal organelles within the AIS and an excellent marker to identify these enigmatic organelles at the light microscopic level. Here we applied 2 h of high frequency stimulation of the medial perforant path in rats in vivo to induce a strong long-term potentiation of dentate gyrus granule cells. Immunolabeling for βIV-spectrin and synaptopodin were performed to study structural changes of the AIS and its cisternal organelles. Three-dimensional analysis of the AIS revealed a shortening of the AIS and a corresponding reduction of the number of synaptopodin clusters. These data demonstrate a rapid structural plasticity of the AIS and its cisternal organelles to strong stimulation, indicating a homeostatic response of the entire AIS compartment.
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Affiliation(s)
- Tassilo Jungenitz
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
- *Correspondence: Tassilo Jungenitz,
| | - Alexander Bird
- Interdisciplinary Centre for 3Rs in Animal Research, Justus Liebig University Giessen, Giessen, Germany
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Johannes Kepler University Linz, Linz, Austria
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
- Interdisciplinary Centre for 3Rs in Animal Research, Justus Liebig University Giessen, Giessen, Germany
| | | | - Thomas Deller
- Institute of Clinical Neuroanatomy, Goethe University Frankfurt, Frankfurt am Main, Germany
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11
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Ramirez-Franco J, Debreux K, Extremet J, Maulet Y, Belghazi M, Villard C, Sangiardi M, Youssouf F, El Far L, Lévêque C, Debarnot C, Marchot P, Paneva S, Debanne D, Russier M, Seagar M, Irani SR, El Far O. Patient-derived antibodies reveal the subcellular distribution and heterogeneous interactome of LGI1. Brain 2022; 145:3843-3858. [PMID: 35727946 DOI: 10.1093/brain/awac218] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 11/14/2022] Open
Abstract
Autoantibodies against leucine-rich glioma-inactivated 1 (LGI1) occur in patients with encephalitis who present with frequent focal seizures and a pattern of amnesia consistent with focal hippocampal damage. To investigate whether the cellular and subcellular distribution of LGI1 may explain the localization of these features, and hence gain broader insights into LGI1's neurobiology, we analysed the detailed localization of LGI1 and the diversity of its protein interactome, in mouse brains using patient-derived recombinant monoclonal LGI1 antibodies. Combined immunofluorescence and mass spectrometry analyses showed that LGI1 is enriched in excitatory and inhibitory synaptic contact sites, most densely within CA3 regions of the hippocampus. LGI1 is secreted in both neuronal somatodendritic and axonal compartments, and occurs in oligodendrocytic, neuro-oligodendrocytic and astro-microglial protein complexes. Proteomic data support the presence of LGI1-Kv1-MAGUK complexes, but did not reveal LGI1 complexes with postsynaptic glutamate receptors. Our results extend our understanding of regional, cellular and subcellular LGI1 expression profiles and reveal novel LGI1-associated complexes, thus providing insights into the complex biology of LGI1 and its relationship to seizures and memory loss.
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Affiliation(s)
- Jorge Ramirez-Franco
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Kévin Debreux
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Johanna Extremet
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Yves Maulet
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Maya Belghazi
- Aix-Marseille University, CNRS, Institute of Neurophysiopathology (INP), PINT, PFNT, 13385 cedex 5 Marseille, France
| | - Claude Villard
- Aix-Marseille University, CNRS, Institute of Neurophysiopathology (INP), PINT, PFNT, 13385 cedex 5 Marseille, France
| | - Marion Sangiardi
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Fahamoe Youssouf
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Lara El Far
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Christian Lévêque
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Claire Debarnot
- Laboratoire 'Architecture et Fonction des Macromolécules Biologiques (AFMB)', CNRS, Aix-Marseille Université, 13288 cedex 09 Marseille, France
| | - Pascale Marchot
- Laboratoire 'Architecture et Fonction des Macromolécules Biologiques (AFMB)', CNRS, Aix-Marseille Université, 13288 cedex 09 Marseille, France
| | - Sofija Paneva
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Dominique Debanne
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Michael Russier
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Michael Seagar
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
| | - Sarosh R Irani
- Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK
- Department of Neurology, Oxford University Hospitals, Oxford, UK
| | - Oussama El Far
- INSERM, Aix-Marseille Université (AMU), UMR 1072, Unité de Neurobiologie des canaux Ioniques et de la Synapse, 13015 Marseille, France
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12
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Senol AD, Pinto G, Beau M, Guillemot V, Dupree JL, Stadelmann C, Ranft J, Lubetzki C, Davenne M. Alterations of the axon initial segment in multiple sclerosis grey matter. Brain Commun 2022; 4:fcac284. [PMID: 36451656 PMCID: PMC9700164 DOI: 10.1093/braincomms/fcac284] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 07/14/2022] [Accepted: 11/02/2022] [Indexed: 07/22/2023] Open
Abstract
Grey matter damage has been established as a key contributor to disability progression in multiple sclerosis. Aside from neuronal loss and axonal transections, which predominate in cortical demyelinated lesions, synaptic alterations have been detected in both demyelinated plaques and normal-appearing grey matter, resulting in functional neuronal damage. The axon initial segment is a key element of neuronal function, responsible for action potential initiation and maintenance of neuronal polarity. Despite several reports of profound axon initial segment alterations in different pathological models, among which experimental auto-immune encephalomyelitis, whether the axon initial segment is affected in multiple sclerosis is still unknown. Using immunohistochemistry, we analysed axon initial segments from control and multiple sclerosis tissue, focusing on layer 5/6 pyramidal neurons in the neocortex and Purkinje cells in the cerebellum and performed analysis on the parameters known to control neuronal excitability, i.e. axon initial segment length and position. We found that the axon initial segment length was increased only in pyramidal neurons of inactive demyelinated lesions, compared with normal appearing grey matter tissue. In contrast, in both cell types, the axon initial segment position was altered, with an increased soma-axon initial segment gap, in both active and inactive demyelinated lesions. In addition, using a computational model, we show that this increased gap between soma and axon initial segment might increase neuronal excitability. Taken together, these results show, for the first time, changes of axon initial segments in multiple sclerosis, in active as well as inactive grey matter lesions in both neocortex and cerebellum, which might alter neuronal function.
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Affiliation(s)
- Aysegul Dilsizoglu Senol
- Sorbonne University, Paris Brain Institute—ICM, Inserm, CNRS, Pitié-Salpêtrière Hospital, Paris, France
| | - Giulia Pinto
- Sorbonne University, Paris Brain Institute—ICM, Inserm, CNRS, Pitié-Salpêtrière Hospital, Paris, France
| | - Maxime Beau
- Institut de Biologie de l’École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Vincent Guillemot
- Sorbonne University, Paris Brain Institute—ICM, Inserm, CNRS, Pitié-Salpêtrière Hospital, Paris, France
- Institut Pasteur, Université de Paris, Bioinformatics and Biostatistics Hub, Paris F-75015, France
| | - Jeffrey L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
- Hunter Holmes McGuire VA Medical Center, Richmond, VA, USA
| | - Christine Stadelmann
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen 37075, Germany
| | - Jonas Ranft
- Institut de Biologie de l’École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Catherine Lubetzki
- Sorbonne University, Paris Brain Institute—ICM, Inserm, CNRS, Pitié-Salpêtrière Hospital, Paris, France
- Assistance Publique des Hôpitaux de Paris (APHP), Pitié-Salpêtrière Hospital, DMU Neurosciences, Paris, France
| | - Marc Davenne
- Correspondence to: Dr Marc Davenne Paris Brain Institute, Pitié-Salpêtrière Hospital 47, bd de l’hôpital, F-75013 Paris, France E-mail:
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13
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Jung K, Choi Y, Kwon HB. Cortical control of chandelier cells in neural codes. Front Cell Neurosci 2022; 16:992409. [PMID: 36299494 PMCID: PMC9588934 DOI: 10.3389/fncel.2022.992409] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/05/2022] [Indexed: 11/28/2022] Open
Abstract
Various cortical functions arise from the dynamic interplay of excitation and inhibition. GABAergic interneurons that mediate synaptic inhibition display significant diversity in cell morphology, electrophysiology, plasticity rule, and connectivity. These heterogeneous features are thought to underlie their functional diversity. Emerging attention on specific properties of the various interneuron types has emphasized the crucial role of cell-type specific inhibition in cortical neural processing. However, knowledge is still limited on how each interneuron type forms distinct neural circuits and regulates network activity in health and disease. To dissect interneuron heterogeneity at single cell-type precision, we focus on the chandelier cell (ChC), one of the most distinctive GABAergic interneuron types that exclusively innervate the axon initial segments (AIS) of excitatory pyramidal neurons. Here we review the current understanding of the structural and functional properties of ChCs and their implications in behavioral functions, network activity, and psychiatric disorders. These findings provide insights into the distinctive roles of various single-type interneurons in cortical neural coding and the pathophysiology of cortical dysfunction.
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14
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Fitzpatrick MJ, Kerschensteiner D. Homeostatic plasticity in the retina. Prog Retin Eye Res 2022; 94:101131. [PMID: 36244950 DOI: 10.1016/j.preteyeres.2022.101131] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 02/07/2023]
Abstract
Vision begins in the retina, whose intricate neural circuits extract salient features of the environment from the light entering our eyes. Neurodegenerative diseases of the retina (e.g., inherited retinal degenerations, age-related macular degeneration, and glaucoma) impair vision and cause blindness in a growing number of people worldwide. Increasing evidence indicates that homeostatic plasticity (i.e., the drive of a neural system to stabilize its function) can, in principle, preserve retinal function in the face of major perturbations, including neurodegeneration. Here, we review the circumstances and events that trigger homeostatic plasticity in the retina during development, sensory experience, and disease. We discuss the diverse mechanisms that cooperate to compensate and the set points and outcomes that homeostatic retinal plasticity stabilizes. Finally, we summarize the opportunities and challenges for unlocking the therapeutic potential of homeostatic plasticity. Homeostatic plasticity is fundamental to understanding retinal development and function and could be an important tool in the fight to preserve and restore vision.
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15
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Hodapp A, Kaiser ME, Thome C, Ding L, Rozov A, Klumpp M, Stevens N, Stingl M, Sackmann T, Lehmann N, Draguhn A, Burgalossi A, Engelhardt M, Both M. Dendritic axon origin enables information gating by perisomatic inhibition in pyramidal neurons. Science 2022; 377:1448-1452. [PMID: 36137045 DOI: 10.1126/science.abj1861] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Information processing in neuronal networks involves the recruitment of selected neurons into coordinated spatiotemporal activity patterns. This sparse activation results from widespread synaptic inhibition in conjunction with neuron-specific synaptic excitation. We report the selective recruitment of hippocampal pyramidal cells into patterned network activity. During ripple oscillations in awake mice, spiking is much more likely in cells in which the axon originates from a basal dendrite rather than from the soma. High-resolution recordings in vitro and computer modeling indicate that these spikes are elicited by synaptic input to the axon-carrying dendrite and thus escape perisomatic inhibition. Pyramidal cells with somatic axon origin can be activated during ripple oscillations by blocking their somatic inhibition. The recruitment of neurons into active ensembles is thus determined by axonal morphological features.
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Affiliation(s)
- Alexander Hodapp
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Martin E Kaiser
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Christian Thome
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany.,Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University, Linz, Austria.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, USA
| | - Lingjun Ding
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.,Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany.,Graduate Training Centre of Neuroscience, IMPRS, Tübingen, Germany
| | - Andrei Rozov
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany.,Federal Center of Brain Research and Neurotechnologies, Moscow, Russian Federation.,OpenLab of Neurobiology, Kazan Federal University, Kazan, Russian Federation
| | - Matthias Klumpp
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Nikolas Stevens
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Moritz Stingl
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Tina Sackmann
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Nadja Lehmann
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
| | - Andrea Burgalossi
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.,Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany
| | - Maren Engelhardt
- Institute of Anatomy and Cell Biology, Medical Faculty, Johannes Kepler University, Linz, Austria.,Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Martin Both
- Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany
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16
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Ostos S, Aparicio G, Fernaud-Espinosa I, DeFelipe J, Muñoz A. Quantitative analysis of the GABAergic innervation of the soma and axon initial segment of pyramidal cells in the human and mouse neocortex. Cereb Cortex 2022; 33:3882-3909. [PMID: 36058205 DOI: 10.1093/cercor/bhac314] [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: 05/20/2022] [Revised: 07/16/2022] [Accepted: 07/17/2022] [Indexed: 11/13/2022] Open
Abstract
Perisomatic GABAergic innervation in the cerebral cortex is carried out mostly by basket and chandelier cells, which differentially participate in the control of pyramidal cell action potential output and synchronization. These cells establish multiple synapses with the cell body (and proximal dendrites) and the axon initial segment (AIS) of pyramidal neurons, respectively. Using multiple immunofluorescence, confocal microscopy and 3D quantification techniques, we have estimated the number and density of GABAergic boutons on the cell body and AIS of pyramidal neurons located through cortical layers of the human and mouse neocortex. The results revealed, in both species, that there is clear variability across layers regarding the density and number of perisomatic GABAergic boutons. We found a positive linear correlation between the surface area of the soma, or the AIS, and the number of GABAergic terminals in apposition to these 2 neuronal domains. Furthermore, the density of perisomatic GABAergic boutons was higher in the human cortex than in the mouse. These results suggest a selectivity for the GABAergic innervation of the cell body and AIS that might be related to the different functional attributes of the microcircuits in which neurons from different layers are involved in both human and mouse.
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Affiliation(s)
- Sandra Ostos
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), Avenida Doctor Arce 37, 28002, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Guillermo Aparicio
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), Avenida Doctor Arce 37, 28002, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Isabel Fernaud-Espinosa
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), Avenida Doctor Arce 37, 28002, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain
| | - Javier DeFelipe
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), Avenida Doctor Arce 37, 28002, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Avenida Monforte de Lemos, 3-5, 28029 Madrid, Spain
| | - Alberto Muñoz
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), Avenida Doctor Arce 37, 28002, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain.,Departamento de Biología Celular, Universidad Complutense, José Antonio Novais 12, 28040 Madrid, Spain
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17
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Pyramidal cell axon initial segment in Alzheimer´s disease. Sci Rep 2022; 12:8722. [PMID: 35610289 PMCID: PMC9130508 DOI: 10.1038/s41598-022-12700-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 05/09/2022] [Indexed: 11/08/2022] Open
Abstract
The axon initial segment (AIS) is a region of the neuron that is critical for action potential generation as well as for the regulation of neural activity. This specialized structure-characterized by the expression of different types of ion channels as well as adhesion, scaffolding and cytoskeleton proteins-is subjected to morpho-functional plastic changes in length and position upon variations in neural activity or in pathological conditions. In the present study, using immunocytochemistry with the AT8 antibody (phospho-tau S202/T205) and 3D confocal microscopy reconstruction techniques in brain tissue from Alzheimer's disease patients, we found that around half of the cortical pyramidal neurons with hyperphosphorylated tau showed changes in AIS length and position in comparison with AT8-negative neurons from the same cortical layers. We observed a wide variety of AIS alterations in neurons with hyperphosphorylated tau, although the most common changes were a proximal shift or a lengthening of the AISs. Similar results were found in neocortical tissue from non-demented cases with neurons containing hyperphosphorylated tau. These findings support the notion that the accumulation of phospho-tau is associated with structural alterations of the AIS that are likely to have an impact on normal neuronal activity, which might contribute to neuronal dysfunction in AD.
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18
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Ultrafast population coding and axo-somatic compartmentalization. PLoS Comput Biol 2022; 18:e1009775. [PMID: 35041645 PMCID: PMC8797191 DOI: 10.1371/journal.pcbi.1009775] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 01/28/2022] [Accepted: 12/16/2021] [Indexed: 02/05/2023] Open
Abstract
Populations of cortical neurons respond to common input within a millisecond. Morphological features and active ion channel properties were suggested to contribute to this astonishing processing speed. Here we report an exhaustive study of ultrafast population coding for varying axon initial segment (AIS) location, soma size, and axonal current properties. In particular, we studied their impact on two experimentally observed features 1) precise action potential timing, manifested in a wide-bandwidth dynamic gain, and 2) high-frequency boost under slowly fluctuating correlated input. While the density of axonal channels and their distance from the soma had a very small impact on bandwidth, it could be moderately improved by increasing soma size. When the voltage sensitivity of axonal currents was increased we observed ultrafast coding and high-frequency boost. We conclude that these computationally relevant features are strongly dependent on axonal ion channels’ voltage sensitivity, but not their number or exact location. We point out that ion channel properties, unlike dendrite size, can undergo rapid physiological modification, suggesting that the temporal accuracy of neuronal population encoding could be dynamically regulated. Our results are in line with recent experimental findings in AIS pathologies and establish a framework to study structure-function relations in AIS molecular design. In large nervous systems, a signal often diverges to hundreds or thousands of neurons. This population’s spike rate can track changes in this common input for frequencies up to several hundred Hertz. This ultrafast population response is experimentally well established and critically impacts cortical information processing. Its underlying biophysical determinants, however, are not understood. Experiments suggest that the ion channels at the axon initial segment strongly contribute to the ultrafast response, but recent theoretical studies emphasize the importance of neuron morphology and the resulting resistive coupling between axon and somato-dendritic compartments. We provide an exhaustive analysis of the population response of a simplified multi-compartment model. We vary the axo-somatic interaction and also active axonal properties and compare models at equivalent working points, avoiding bias. This approach provides a guideline for future experimental and theoretical studies. In this framework, the population response is closely associated with the AP generation speed at the AP initiation site, which is mostly determined by axonal ion channel voltage sensitivity. The resistive axo-somatic coupling has an additional modulatory influence. These insights are expected to hold for encoding mechanisms of more sophisticated models, suggesting that physiological changes to axonal ion channels could modulate the population response rapidly.
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19
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PESARICO ANAPAULA, CECHELLA JOSÉL, NOGUEIRA CRISTINAW, ROSA SUZANG. Swimming exercise and diphenyl diselenide-supplemented diet modulate cerebral cortical and striatal GABA uptake in aged rats. AN ACAD BRAS CIENC 2022; 94:e20200844. [DOI: 10.1590/0001-3765202220200844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 01/21/2021] [Indexed: 11/21/2022] Open
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20
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Schneider-Mizell CM, Bodor AL, Collman F, Brittain D, Bleckert A, Dorkenwald S, Turner NL, Macrina T, Lee K, Lu R, Wu J, Zhuang J, Nandi A, Hu B, Buchanan J, Takeno MM, Torres R, Mahalingam G, Bumbarger DJ, Li Y, Chartrand T, Kemnitz N, Silversmith WM, Ih D, Zung J, Zlateski A, Tartavull I, Popovych S, Wong W, Castro M, Jordan CS, Froudarakis E, Becker L, Suckow S, Reimer J, Tolias AS, Anastassiou CA, Seung HS, Reid RC, da Costa NM. Structure and function of axo-axonic inhibition. eLife 2021; 10:e73783. [PMID: 34851292 PMCID: PMC8758143 DOI: 10.7554/elife.73783] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
Inhibitory neurons in mammalian cortex exhibit diverse physiological, morphological, molecular, and connectivity signatures. While considerable work has measured the average connectivity of several interneuron classes, there remains a fundamental lack of understanding of the connectivity distribution of distinct inhibitory cell types with synaptic resolution, how it relates to properties of target cells, and how it affects function. Here, we used large-scale electron microscopy and functional imaging to address these questions for chandelier cells in layer 2/3 of the mouse visual cortex. With dense reconstructions from electron microscopy, we mapped the complete chandelier input onto 153 pyramidal neurons. We found that synapse number is highly variable across the population and is correlated with several structural features of the target neuron. This variability in the number of axo-axonic ChC synapses is higher than the variability seen in perisomatic inhibition. Biophysical simulations show that the observed pattern of axo-axonic inhibition is particularly effective in controlling excitatory output when excitation and inhibition are co-active. Finally, we measured chandelier cell activity in awake animals using a cell-type-specific calcium imaging approach and saw highly correlated activity across chandelier cells. In the same experiments, in vivo chandelier population activity correlated with pupil dilation, a proxy for arousal. Together, these results suggest that chandelier cells provide a circuit-wide signal whose strength is adjusted relative to the properties of target neurons.
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Affiliation(s)
| | - Agnes L Bodor
- Allen Institute for Brain SciencesSeattleUnited States
| | | | | | - Adam Bleckert
- Allen Institute for Brain SciencesSeattleUnited States
| | - Sven Dorkenwald
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Nicholas L Turner
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Thomas Macrina
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - Kisuk Lee
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Brain & Cognitive Sciences Department, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ran Lu
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Jingpeng Wu
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Jun Zhuang
- Allen Institute for Brain SciencesSeattleUnited States
| | - Anirban Nandi
- Allen Institute for Brain SciencesSeattleUnited States
| | - Brian Hu
- Allen Institute for Brain SciencesSeattleUnited States
| | | | - Marc M Takeno
- Allen Institute for Brain SciencesSeattleUnited States
| | - Russel Torres
- Allen Institute for Brain SciencesSeattleUnited States
| | | | | | - Yang Li
- Allen Institute for Brain SciencesSeattleUnited States
| | | | - Nico Kemnitz
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | | | - Dodam Ih
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Jonathan Zung
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Aleksandar Zlateski
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Ignacio Tartavull
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Sergiy Popovych
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - William Wong
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Manuel Castro
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Chris S Jordan
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
| | - Emmanouil Froudarakis
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
| | - Lynne Becker
- Allen Institute for Brain SciencesSeattleUnited States
| | - Shelby Suckow
- Allen Institute for Brain SciencesSeattleUnited States
| | - Jacob Reimer
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
| | - Andreas S Tolias
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Center for Neuroscience and Artificial Intelligence, Baylor College of MedicineHoustonUnited States
- Department of Electrical and Computer Engineering, Rice UniversityHoustonUnited States
| | - Costas A Anastassiou
- Allen Institute for Brain SciencesSeattleUnited States
- Department of Neurology, University of British ColumbiaVancouverCanada
| | - H Sebastian Seung
- Princeton Neuroscience Institute, Princeton UniversityPrincetonUnited States
- Computer Science Department, Princeton UniversityPrincetonUnited States
| | - R Clay Reid
- Allen Institute for Brain SciencesSeattleUnited States
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21
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Lezmy J, Arancibia-Carcamo L, Quintela-Lopez T, Sherman DL, Brophy PJ, Attwell D. Astrocyte Ca 2+-evoked ATP release regulates myelinated axon excitability and conduction speed. Science 2021; 374:eabh2858. [PMID: 34648330 PMCID: PMC7611967 DOI: 10.1126/science.abh2858] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the brain’s gray matter, astrocytes regulate synapse properties, but their role is unclear for the white matter, where myelinated axons rapidly transmit information between gray matter areas. We found that in rodents, neuronal activity raised the intracellular calcium concentration ([Ca2+]i) in astrocyte processes located near action potential–generating sites in the axon initial segment (AIS) and nodes of Ranvier of myelinated axons. This released adenosine triphosphate, which was converted extracellularly to adenosine and thus, through A2a receptors, activated HCN2-containing cation channels that regulate two aspects of myelinated axon function: excitability of the AIS and speed of action potential propagation. Variations in astrocyte-derived adenosine level between wake and sleep states or during energy deprivation could thus control white matter information flow and neural circuit function.
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Affiliation(s)
- Jonathan Lezmy
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Lorena Arancibia-Carcamo
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
- Dementia Research Institute, Francis Crick Institute 1 Midland Rd, London, NW1 1AT, UK
| | - Tania Quintela-Lopez
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Diane L. Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Chancellor’s Building, Edinburgh, EH16 4SB
| | - Peter J. Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Chancellor’s Building, Edinburgh, EH16 4SB
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
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22
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Gutman-Wei AY, Brown SP. Mechanisms Underlying Target Selectivity for Cell Types and Subcellular Domains in Developing Neocortical Circuits. Front Neural Circuits 2021; 15:728832. [PMID: 34630048 PMCID: PMC8497978 DOI: 10.3389/fncir.2021.728832] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/25/2021] [Indexed: 11/25/2022] Open
Abstract
The cerebral cortex contains numerous neuronal cell types, distinguished by their molecular identity as well as their electrophysiological and morphological properties. Cortical function is reliant on stereotyped patterns of synaptic connectivity and synaptic function among these neuron types, but how these patterns are established during development remains poorly understood. Selective targeting not only of different cell types but also of distinct postsynaptic neuronal domains occurs in many brain circuits and is directed by multiple mechanisms. These mechanisms include the regulation of axonal and dendritic guidance and fine-scale morphogenesis of pre- and postsynaptic processes, lineage relationships, activity dependent mechanisms and intercellular molecular determinants such as transmembrane and secreted molecules, many of which have also been implicated in neurodevelopmental disorders. However, many studies of synaptic targeting have focused on circuits in which neuronal processes target different lamina, such that cell-type-biased connectivity may be confounded with mechanisms of laminar specificity. In the cerebral cortex, each cortical layer contains cell bodies and processes from intermingled neuronal cell types, an arrangement that presents a challenge for the development of target-selective synapse formation. Here, we address progress and future directions in the study of cell-type-biased synaptic targeting in the cerebral cortex. We highlight challenges to identifying developmental mechanisms generating stereotyped patterns of intracortical connectivity, recent developments in uncovering the determinants of synaptic target selection during cortical synapse formation, and current gaps in the understanding of cortical synapse specificity.
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Affiliation(s)
- Alan Y. Gutman-Wei
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Solange P. Brown
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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23
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Paredes-Redondo A, Harley P, Maniati E, Ryan D, Louzada S, Meng J, Kowala A, Fu B, Yang F, Liu P, Marino S, Pourquié O, Muntoni F, Wang J, Lieberam I, Lin YY. Optogenetic modeling of human neuromuscular circuits in Duchenne muscular dystrophy with CRISPR and pharmacological corrections. SCIENCE ADVANCES 2021; 7:eabi8787. [PMID: 34516770 PMCID: PMC8442926 DOI: 10.1126/sciadv.abi8787] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/20/2021] [Indexed: 05/13/2023]
Abstract
Duchenne muscular dystrophy (DMD) is caused by dystrophin gene mutations leading to skeletal muscle weakness and wasting. Dystrophin is enriched at the neuromuscular junction (NMJ), but how NMJ abnormalities contribute to DMD pathogenesis remains unclear. Here, we combine transcriptome analysis and modeling of DMD patient-derived neuromuscular circuits with CRISPR-corrected isogenic controls in compartmentalized microdevices. We show that NMJ volumes and optogenetic motor neuron–stimulated myofiber contraction are compromised in DMD neuromuscular circuits, which can be rescued by pharmacological inhibition of TGFβ signaling, an observation validated in a 96-well human neuromuscular circuit coculture assay. These beneficial effects are associated with normalization of dysregulated gene expression in DMD myogenic transcriptomes affecting NMJ assembly (e.g., MUSK) and axon guidance (e.g., SLIT2 and SLIT3). Our study provides a new human microphysiological model for investigating NMJ defects in DMD and assessing candidate drugs and suggests that enhancing neuromuscular connectivity may be an effective therapeutic strategy.
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Affiliation(s)
- Amaia Paredes-Redondo
- Centre for Genomics and Child Health, Blizard
Institute, Barts and the London School of Medicine and Dentistry, Queen Mary
University of London, 4 Newark Street, London E1 2AT, UK
- Stem Cell Laboratory, National Bowel Research Centre,
Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen
Mary University of London, 2 Newark Street, London E1 2AT, UK
- Centre for Predictive in vitro Model, Queen Mary
University of London, Mile End Road, London E1 4NS, UK
| | - Peter Harley
- Centre for Stem Cells and Regenerative Medicine, MRC
Centre for Neurodevelopmental Disorders, and Centre for Developmental
Neurobiology, King’s College London, London, UK
| | - Eleni Maniati
- Centre for Cancer Genomics and Computational Biology,
Barts Cancer Institute, Queen Mary University of London, London, UK
| | - David Ryan
- Wellcome Sanger Institute, Wellcome Genome Campus,
Hinxton, Cambridge CB10 1SA, UK
| | - Sandra Louzada
- Wellcome Sanger Institute, Wellcome Genome Campus,
Hinxton, Cambridge CB10 1SA, UK
| | - Jinhong Meng
- UCL Great Ormond Street Institute of Child Health, 30
Guilford Street, London WC1N 1EH, UK
| | - Anna Kowala
- Centre for Genomics and Child Health, Blizard
Institute, Barts and the London School of Medicine and Dentistry, Queen Mary
University of London, 4 Newark Street, London E1 2AT, UK
- Stem Cell Laboratory, National Bowel Research Centre,
Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen
Mary University of London, 2 Newark Street, London E1 2AT, UK
- Centre for Predictive in vitro Model, Queen Mary
University of London, Mile End Road, London E1 4NS, UK
| | - Beiyuan Fu
- Wellcome Sanger Institute, Wellcome Genome Campus,
Hinxton, Cambridge CB10 1SA, UK
| | - Fengtang Yang
- Wellcome Sanger Institute, Wellcome Genome Campus,
Hinxton, Cambridge CB10 1SA, UK
| | - Pentao Liu
- School of Biomedical Sciences, Stem Cell and
Regenerative Medicine Consortium, Li Ka Shing Faculty of Medicine, The
University of Hong Kong, Hong Kong, China
| | - Silvia Marino
- Centre for Genomics and Child Health, Blizard
Institute, Barts and the London School of Medicine and Dentistry, Queen Mary
University of London, 4 Newark Street, London E1 2AT, UK
| | - Olivier Pourquié
- Department of Genetics and Department of Pathology,
Brigham and Women’s Hospital, Harvard Medical School, 60 Fenwood Road,
Boston, MA, USA
| | - Francesco Muntoni
- UCL Great Ormond Street Institute of Child Health, 30
Guilford Street, London WC1N 1EH, UK
- NIHR Biomedical Research Centre, Great Ormond
Street Hospital, Great Ormond Street, London, UK
| | - Jun Wang
- Centre for Cancer Genomics and Computational Biology,
Barts Cancer Institute, Queen Mary University of London, London, UK
| | - Ivo Lieberam
- Centre for Stem Cells and Regenerative Medicine, MRC
Centre for Neurodevelopmental Disorders, and Centre for Developmental
Neurobiology, King’s College London, London, UK
| | - Yung-Yao Lin
- Centre for Genomics and Child Health, Blizard
Institute, Barts and the London School of Medicine and Dentistry, Queen Mary
University of London, 4 Newark Street, London E1 2AT, UK
- Stem Cell Laboratory, National Bowel Research Centre,
Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen
Mary University of London, 2 Newark Street, London E1 2AT, UK
- Centre for Predictive in vitro Model, Queen Mary
University of London, Mile End Road, London E1 4NS, UK
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24
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Neural excitability increases with axonal resistance between soma and axon initial segment. Proc Natl Acad Sci U S A 2021; 118:2102217118. [PMID: 34389672 DOI: 10.1073/pnas.2102217118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The position of the axon initial segment (AIS) is thought to play a critical role in neuronal excitability. Previous experimental studies have found that a distal shift in AIS position correlates with a reduction in excitability. Yet theoretical work has suggested the opposite, because of increased electrical isolation. A distal shift in AIS position corresponds to an elevation of axial resistance R a We therefore examined how changes in R a at the axon hillock impact the voltage threshold (Vth) of the somatic action potential in L5 pyramidal neurons. Increasing R a by mechanically pinching the axon between the soma and the AIS was found to lower Vth by ∼6 mV. Conversely, decreasing R a by substituting internal ions with higher mobility elevated Vth All R a -dependent changes in Vth could be reproduced in a Hodgkin-Huxley compartmental model. We conclude that in L5 pyramidal neurons, excitability increases with axial resistance and therefore with a distal shift of the AIS.
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25
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Plasmalogens regulate the AKT-ULK1 signaling pathway to control the position of the axon initial segment. Prog Neurobiol 2021; 205:102123. [PMID: 34302896 DOI: 10.1016/j.pneurobio.2021.102123] [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: 01/20/2021] [Revised: 06/11/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023]
Abstract
The axon initial segment (AIS) is a specialized region in neurons that encompasses two essential functions, the generation of action potentials and the regulation of the axodendritic polarity. The mechanism controlling the position of the axon initial segment to allow plasticity and regulation of neuron excitability is unclear. Here we demonstrate that plasmalogens, the most abundant ether-phospholipid, are essential for the homeostatic positioning of the AIS. Plasmalogen deficiency is a hallmark of Rhizomelic Chondrodysplasia Punctata (RCDP) and Zellweger spectrum disorders, but Alzheimer's and Parkinson's disease, are also characterized by plasmalogen defects. Neurons lacking plasmalogens displaced the AIS to more distal positions and were characterized by reduced excitability. Treatment with a short-chain alkyl glycerol was able to rescue AIS positioning. Plasmalogen deficiency impaired AKT activation, and we show that inhibition of AKT phosphorylation at Ser473 and Thr308 is sufficient to induce a distal relocation of the AIS. Pathway analysis revealed that downstream of AKT, overtly active ULK1 mediates AIS repositioning. Rescuing the impaired AKT signaling pathway was able to normalize AIS position independently of the biochemical defect. These results unveil a previously unknown mechanism that couples the phospholipid composition of the neuronal membrane to the positional assembly of the AIS.
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26
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Galliano E, Hahn C, Browne LP, R Villamayor P, Tufo C, Crespo A, Grubb MS. Brief Sensory Deprivation Triggers Cell Type-Specific Structural and Functional Plasticity in Olfactory Bulb Neurons. J Neurosci 2021; 41:2135-2151. [PMID: 33483429 PMCID: PMC8018761 DOI: 10.1523/jneurosci.1606-20.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/11/2020] [Accepted: 11/17/2020] [Indexed: 02/03/2023] Open
Abstract
Can alterations in experience trigger different plastic modifications in neuronal structure and function, and if so, how do they integrate at the cellular level? To address this question, we interrogated circuitry in the mouse olfactory bulb responsible for the earliest steps in odor processing. We induced experience-dependent plasticity in mice of either sex by blocking one nostril for one day, a minimally invasive manipulation that leaves the sensory organ undamaged and is akin to the natural transient blockage suffered during common mild rhinal infections. We found that such brief sensory deprivation produced structural and functional plasticity in one highly specialized bulbar cell type: axon-bearing dopaminergic neurons in the glomerular layer. After 24 h naris occlusion, the axon initial segment (AIS) in bulbar dopaminergic neurons became significantly shorter, a structural modification that was also associated with a decrease in intrinsic excitability. These effects were specific to the AIS-positive dopaminergic subpopulation because no experience-dependent alterations in intrinsic excitability were observed in AIS-negative dopaminergic cells. Moreover, 24 h naris occlusion produced no structural changes at the AIS of bulbar excitatory neurons, mitral/tufted and external tufted cells, nor did it alter their intrinsic excitability. By targeting excitability in one specialized dopaminergic subpopulation, experience-dependent plasticity in early olfactory networks might act to fine-tune sensory processing in the face of continually fluctuating inputs.SIGNIFICANCE STATEMENT Sensory networks need to be plastic so they can adapt to changes in incoming stimuli. To see how cells in mouse olfactory circuits can change in response to sensory challenges, we blocked a nostril for just one day, a naturally relevant manipulation akin to the deprivation that occurs with a mild cold. We found that this brief deprivation induces forms of axonal and intrinsic functional plasticity in one specific olfactory bulb cell subtype: axon-bearing dopaminergic interneurons. In contrast, intrinsic properties of axon-lacking bulbar dopaminergic neurons and neighboring excitatory neurons remained unchanged. Within the same sensory circuits, specific cell types can therefore make distinct plastic changes in response to an ever-changing external landscape.
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Affiliation(s)
- Elisa Galliano
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3DY, United Kingdom
| | - Christiane Hahn
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
| | - Lorcan P Browne
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
| | - Paula R Villamayor
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
| | - Candida Tufo
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
| | - Andres Crespo
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
| | - Matthew S Grubb
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE1 1UL, United Kingdom
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27
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Hildebrandt-Einfeldt L, Yap K, Paul MH, Stoffer C, Zahn N, Drakew A, Lenz M, Vlachos A, Deller T. Crossed Entorhino-Dentate Projections Form and Terminate With Correct Layer-Specificity in Organotypic Slice Cultures of the Mouse Hippocampus. Front Neuroanat 2021; 15:637036. [PMID: 33643001 PMCID: PMC7904698 DOI: 10.3389/fnana.2021.637036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/12/2021] [Indexed: 11/13/2022] Open
Abstract
The entorhino-dentate projection, i.e., the perforant pathway, terminates in a highly ordered and laminated fashion in the rodent dentate gyrus (DG): fibers arising from the medial entorhinal cortex (MEC) terminate in the middle molecular layer, whereas fibers arising from the lateral entorhinal cortex (LEC) terminate in the outer molecular layer of the DG. In rats and rabbits, a crossed entorhino-dentate projection exists, which originates from the entorhinal cortex (EC) and terminates in the contralateral DG. In contrast, in mice, such a crossed projection is reportedly absent. Using single and double mouse organotypic entorhino-hippocampal slice cultures, we studied the ipsi- and crossed entorhino-dentate projections. Viral tracing revealed that entorhino-dentate projections terminate with a high degree of lamina-specificity in single as well as in double cultures. Furthermore, in double cultures, entorhinal axons arising from one slice freely intermingled with entorhinal axons originating from the other slice. In single as well as in double cultures, entorhinal axons exhibited a correct topographical projection to the DG: medial entorhinal axons terminated in the middle and lateral entorhinal axons terminated in the outer molecular layer. Finally, entorhinal neurons were virally transduced with Channelrhodopsin2-YFP and stimulated with light, revealing functional connections between the EC and dentate granule cells. We conclude from our findings that entorhino-dentate projections form bilaterally in the mouse hippocampus in vitro and that the mouse DG provides a permissive environment for crossed entorhinal fibers.
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Affiliation(s)
- Lars Hildebrandt-Einfeldt
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Kenrick Yap
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Carolin Stoffer
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Nadine Zahn
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Alexander Drakew
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
| | - Maximilian Lenz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Center Brain Links Brain Tools, University of Freiburg, Freiburg, Germany.,Center for Basics in Neuro Modulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Dr. Senckenberg Anatomy, Neuroscience Center, Goethe-University Frankfurt, Frankfurt, Germany
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28
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Jamann N, Dannehl D, Lehmann N, Wagener R, Thielemann C, Schultz C, Staiger J, Kole MHP, Engelhardt M. Sensory input drives rapid homeostatic scaling of the axon initial segment in mouse barrel cortex. Nat Commun 2021; 12:23. [PMID: 33397944 PMCID: PMC7782484 DOI: 10.1038/s41467-020-20232-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 11/16/2020] [Indexed: 12/12/2022] Open
Abstract
The axon initial segment (AIS) is a critical microdomain for action potential initiation and implicated in the regulation of neuronal excitability during activity-dependent plasticity. While structural AIS plasticity has been suggested to fine-tune neuronal activity when network states change, whether it acts in vivo as a homeostatic regulatory mechanism in behaviorally relevant contexts remains poorly understood. Using the mouse whisker-to-barrel pathway as a model system in combination with immunofluorescence, confocal analysis and electrophysiological recordings, we observed bidirectional AIS plasticity in cortical pyramidal neurons. Furthermore, we find that structural and functional AIS remodeling occurs in distinct temporal domains: Long-term sensory deprivation elicits an AIS length increase, accompanied with an increase in neuronal excitability, while sensory enrichment results in a rapid AIS shortening, accompanied by a decrease in action potential generation. Our findings highlight a central role of the AIS in the homeostatic regulation of neuronal input-output relations.
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Affiliation(s)
- Nora Jamann
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, The Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dominik Dannehl
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Nadja Lehmann
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Robin Wagener
- Clinic of Neurology, University Hospital Heidelberg, Heidelberg, Germany
| | - Corinna Thielemann
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Christian Schultz
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jochen Staiger
- Institute of Neuroanatomy, University Medical Center, Georg August University of Göttingen, Göttingen, Germany
| | - Maarten H P Kole
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, The Netherlands.
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
| | - Maren Engelhardt
- Institute of Neuroanatomy, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
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29
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Lee M, Liu YC, Chen C, Lu CH, Lu ST, Huang TN, Hsu MT, Hsueh YP, Cheng PL. Ecm29-mediated proteasomal distribution modulates excitatory GABA responses in the developing brain. J Cell Biol 2020; 219:133566. [PMID: 31910261 PMCID: PMC7041676 DOI: 10.1083/jcb.201903033] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 10/14/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022] Open
Abstract
Neuronal GABAergic responses switch from excitatory to inhibitory at an early postnatal period in rodents. The timing of this switch is controlled by intracellular Cl− concentrations, but factors determining local levels of cation-chloride cotransporters remain elusive. Here, we report that local abundance of the chloride importer NKCC1 and timely emergence of GABAergic inhibition are modulated by proteasome distribution, which is mediated through interactions of proteasomes with the adaptor Ecm29 and the axon initial segment (AIS) scaffold protein ankyrin G. Mechanistically, both the Ecm29 N-terminal domain and an intact AIS structure are required for transport and tethering of proteasomes in the AIS region. In mice, Ecm29 knockout (KO) in neurons increases the density of NKCC1 protein in the AIS region, a change that positively correlates with a delay in the GABAergic response switch. Phenotypically, Ecm29 KO mice showed increased firing frequency of action potentials at early postnatal ages and were hypersusceptible to chemically induced convulsive seizures. Finally, Ecm29 KO neurons exhibited accelerated AIS developmental positioning, reflecting a perturbed AIS morphological plastic response to hyperexcitability arising from proteasome inhibition, a phenotype rescued by ectopic Ecm29 expression or NKCC1 inhibition. Together, our findings support the idea that neuronal maturation requires regulation of proteasomal distribution controlled by Ecm29.
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Affiliation(s)
- Min Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yen-Chen Liu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Chen Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Chi-Huan Lu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Shao-Tzu Lu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Tzyy-Nan Huang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Meng-Tsung Hsu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Pei-Lin Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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30
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Lipkin AM, Bender KJ. Flipping the Switch: Homeostatic Tuning of Chandelier Synapses Follows Developmental Changes in GABA Polarity. Neuron 2020; 106:199-201. [PMID: 32325052 DOI: 10.1016/j.neuron.2020.03.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Homeostatic plasticity rules are well described for glutamatergic synapses but less clear for GABAergic synapses. In this issue of Neuron, Pan-Vazquez et al. (2020) leverage the precise targeting of chandelier-to-pyramidal cell connectivity to understand how homeostatic plasticity regulates GABAergic synapses, showing that these synapses maintain homeostatic rules even as they flip from exciting to inhibiting pyramidal cells.
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Affiliation(s)
- Anna M Lipkin
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA; Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Kevin J Bender
- Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
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31
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Pan-Vazquez A, Wefelmeyer W, Gonzalez Sabater V, Neves G, Burrone J. Activity-Dependent Plasticity of Axo-axonic Synapses at the Axon Initial Segment. Neuron 2020; 106:265-276.e6. [PMID: 32109363 PMCID: PMC7181187 DOI: 10.1016/j.neuron.2020.01.037] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 12/06/2019] [Accepted: 01/27/2020] [Indexed: 12/20/2022]
Abstract
The activity-dependent rules that govern the wiring of GABAergic interneurons are not well understood. Chandelier cells (ChCs) are a type of GABAergic interneuron that control pyramidal cell output through axo-axonic synapses that target the axon initial segment. In vivo imaging of ChCs during development uncovered a narrow window (P12-P18) over which axons arborized and formed connections. We found that increases in the activity of either pyramidal cells or individual ChCs during this temporal window result in a reversible decrease in axo-axonic connections. Voltage imaging of GABAergic transmission at the axon initial segment (AIS) showed that axo-axonic synapses were depolarizing during this period. Identical manipulations of network activity in older mice (P40-P46), when ChC synapses are inhibitory, resulted instead in an increase in axo-axonic synapses. We propose that the direction of ChC synaptic plasticity follows homeostatic rules that depend on the polarity of axo-axonic synapses.
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Affiliation(s)
- Alejandro Pan-Vazquez
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
| | - Winnie Wefelmeyer
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
| | - Victoria Gonzalez Sabater
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK
| | - Guilherme Neves
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; The Rosalind Franklin Institute, Harwell Campus, Didcot OX11 0FA, UK
| | - Juan Burrone
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK; Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, UK.
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32
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Goethals S, Brette R. Theoretical relation between axon initial segment geometry and excitability. eLife 2020; 9:53432. [PMID: 32223890 PMCID: PMC7170651 DOI: 10.7554/elife.53432] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/30/2020] [Indexed: 12/29/2022] Open
Abstract
In most vertebrate neurons, action potentials are triggered at the distal end of the axon initial segment (AIS). Both position and length of the AIS vary across and within neuron types, with activity, development and pathology. What is the impact of AIS geometry on excitability? Direct empirical assessment has proven difficult because of the many potential confounding factors. Here, we carried a principled theoretical analysis to answer this question. We provide a simple formula relating AIS geometry and sodium conductance density to the somatic voltage threshold. A distal shift of the AIS normally produces a (modest) increase in excitability, but we explain how this pattern can reverse if a hyperpolarizing current is present at the AIS, due to resistive coupling with the soma. This work provides a theoretical tool to assess the significance of structural AIS plasticity for electrical function.
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Affiliation(s)
- Sarah Goethals
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Romain Brette
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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33
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Gandolfi D, Bigiani A, Porro CA, Mapelli J. Inhibitory Plasticity: From Molecules to Computation and Beyond. Int J Mol Sci 2020; 21:E1805. [PMID: 32155701 PMCID: PMC7084224 DOI: 10.3390/ijms21051805] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/28/2020] [Accepted: 03/03/2020] [Indexed: 11/17/2022] Open
Abstract
Synaptic plasticity is the cellular and molecular counterpart of learning and memory and, since its first discovery, the analysis of the mechanisms underlying long-term changes of synaptic strength has been almost exclusively focused on excitatory connections. Conversely, inhibition was considered as a fixed controller of circuit excitability. Only recently, inhibitory networks were shown to be finely regulated by a wide number of mechanisms residing in their synaptic connections. Here, we review recent findings on the forms of inhibitory plasticity (IP) that have been discovered and characterized in different brain areas. In particular, we focus our attention on the molecular pathways involved in the induction and expression mechanisms leading to changes in synaptic efficacy, and we discuss, from the computational perspective, how IP can contribute to the emergence of functional properties of brain circuits.
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Affiliation(s)
- Daniela Gandolfi
- Department of Biomedical, Metabolic and Neural Sciences and Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (D.G.); (A.B.); (C.A.P.)
- Department of Brain and behavioral sciences, University of Pavia, 27100 Pavia, Italy
| | - Albertino Bigiani
- Department of Biomedical, Metabolic and Neural Sciences and Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (D.G.); (A.B.); (C.A.P.)
| | - Carlo Adolfo Porro
- Department of Biomedical, Metabolic and Neural Sciences and Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (D.G.); (A.B.); (C.A.P.)
| | - Jonathan Mapelli
- Department of Biomedical, Metabolic and Neural Sciences and Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (D.G.); (A.B.); (C.A.P.)
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34
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Goaillard JM, Moubarak E, Tapia M, Tell F. Diversity of Axonal and Dendritic Contributions to Neuronal Output. Front Cell Neurosci 2020; 13:570. [PMID: 32038171 PMCID: PMC6987044 DOI: 10.3389/fncel.2019.00570] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/09/2019] [Indexed: 11/13/2022] Open
Abstract
Our general understanding of neuronal function is that dendrites receive information that is transmitted to the axon, where action potentials (APs) are initiated and propagated to eventually trigger neurotransmitter release at synaptic terminals. Even though this canonical division of labor is true for a number of neuronal types in the mammalian brain (including neocortical and hippocampal pyramidal neurons or cerebellar Purkinje neurons), many neuronal types do not comply with this classical polarity scheme. In fact, dendrites can be the site of AP initiation and propagation, and even neurotransmitter release. In several interneuron types, all functions are carried out by dendrites as these neurons are devoid of a canonical axon. In this article, we present a few examples of "misbehaving" neurons (with a non-canonical polarity scheme) to highlight the diversity of solutions that are used by mammalian neurons to transmit information. Moreover, we discuss how the contribution of dendrites and axons to neuronal excitability may impose constraints on the morphology of these compartments in specific functional contexts.
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Affiliation(s)
- Jean-Marc Goaillard
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Estelle Moubarak
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Mónica Tapia
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Fabien Tell
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
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35
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Kim EJ, Feng C, Santamaria F, Kim JH. Impact of Auditory Experience on the Structural Plasticity of the AIS in the Mouse Brainstem Throughout the Lifespan. Front Cell Neurosci 2019; 13:456. [PMID: 31680869 PMCID: PMC6813928 DOI: 10.3389/fncel.2019.00456] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/25/2019] [Indexed: 12/18/2022] Open
Abstract
Sound input critically influences the development and maintenance of neuronal circuits in the mammalian brain throughout life. We investigate the structural and functional plasticity of auditory neurons in response to various auditory experiences during development, adulthood, and aging. Using electrophysiology, computer simulation, and immunohistochemistry, we study the structural plasticity of the axon initial segment (AIS) in the medial nucleus of the trapezoid body (MNTB) from the auditory brainstem of the mice (either sex), in different ages and auditory environments. The structure and spatial location of the AIS of MNTB neurons depend on their functional topographic location along the tonotopic axis, aligning high- to low-frequency sound-responding neurons (HF or LF neurons). HF neurons dramatically undergo structural remodeling of the AIS throughout life. The AIS progressively shortens during development, is stabilized in adulthood, and becomes longer in aging. Sound inputs are critically associated with setting and maintaining AIS plasticity and tonotopy at various ages. Sound stimulation increases the excitability of auditory neurons. Computer simulation shows that modification of the AIS length, location, and diameter can affect firing properties of MNTB neurons in the developing brainstem. The adaptive capability of axonal structure in response to various auditory experiences at different ages suggests that sound input is important for the development and maintenance of the structural and functional properties of the auditory brain throughout life.
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Affiliation(s)
- Eun Jung Kim
- The Department of Cellular and Integrative Physiology, UT Health San Antonio, San Antonio, TX, United States
| | - Chenling Feng
- The Department of Biology, University of Texas, San Antonio, TX, United States
| | - Fidel Santamaria
- The Department of Biology, University of Texas, San Antonio, TX, United States
| | - Jun Hee Kim
- The Department of Cellular and Integrative Physiology, UT Health San Antonio, San Antonio, TX, United States
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36
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Cilia function is associated with axon initial segment morphology. Biochem Biophys Res Commun 2019; 516:15-21. [DOI: 10.1016/j.bbrc.2019.05.172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 12/25/2022]
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37
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Machado CB, Pluchon P, Harley P, Rigby M, Gonzalez Sabater V, Stevenson DC, Hynes S, Lowe A, Burrone J, Viasnoff V, Lieberam I. In Vitro Modelling of Nerve-Muscle Connectivity in a Compartmentalised Tissue Culture Device. ADVANCED BIOSYSTEMS 2019; 3:1800307. [PMID: 31428672 PMCID: PMC6699992 DOI: 10.1002/adbi.201800307] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Indexed: 01/02/2023]
Abstract
Motor neurons project axons from the hindbrain and spinal cord to muscle, where they induce myofibre contractions through neurotransmitter release at neuromuscular junctions. Studies of neuromuscular junction formation and homeostasis have been largely confined to in vivo models. In this study we have merged three powerful tools - pluripotent stem cells, optogenetics and microfabrication - and designed an open microdevice in which motor axons grow from a neural compartment containing embryonic stem cell-derived motor neurons and astrocytes through microchannels to form functional neuromuscular junctions with contractile myofibers in a separate compartment. Optogenetic entrainment of motor neurons in this reductionist neuromuscular circuit enhanced neuromuscular junction formation more than two-fold, mirroring the activity-dependence of synapse development in vivo. We incorporated an established motor neuron disease model into our system and found that coculture of motor neurons with SOD1G93A astrocytes resulted in denervation of the central compartment and diminished myofiber contractions, a phenotype which was rescued by the Receptor Interacting Serine/Threonine Kinase 1 (RIPK1) inhibitor Necrostatin. This coculture system replicates key aspects of nerve-muscle connectivity in vivo and represents a rapid and scalable alternative to animal models of neuromuscular function and disease.
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Affiliation(s)
- Carolina Barcellos Machado
- Centre for Stem Cells and Regenerative Medicine, King’s
College London, London SE1 9RT, UK; Centre for Developmental
Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s
College London, London SE1 1UL, UK
| | - Perrine Pluchon
- Centre for Stem Cells and Regenerative Medicine, King’s
College London, London SE1 9RT, UK; Centre for Developmental
Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s
College London, London SE1 1UL, UK; Mechanobiology Institute, National
University of Singapore, Singapore 117411
| | - Peter Harley
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London SE1 9RT, UK; Centre for Developmental Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s College London, London SE1 1UL, UK
| | | | - Victoria Gonzalez Sabater
- Centre for Developmental Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s College London, London SE1 1UL, UK
| | | | - Stephanie Hynes
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London SE1 9RT, UK; Centre for Developmental Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s College London, London SE1 1UL, UK
| | - Andrew Lowe
- Centre for Developmental Neurobiology, King’s College London, London SE1 1UL, UK
| | - Juan Burrone
- Centre for Developmental Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s College London, London SE1 1UL, UK
| | - Virgile Viasnoff
- Mechanobiology Institute, National University of Singapore,
Singapore 117411
| | - Ivo Lieberam
- Centre for Stem Cells and Regenerative Medicine, King’s
College London, London SE1 9RT, UK; Centre for Developmental
Neurobiology/MRC Centre for Neurodevelopmental Disorders, King’s
College London, London SE1 1UL, UK
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38
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Robustness to Axon Initial Segment Variation Is Explained by Somatodendritic Excitability in Rat Substantia Nigra Dopaminergic Neurons. J Neurosci 2019; 39:5044-5063. [PMID: 31028116 DOI: 10.1523/jneurosci.2781-18.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 01/12/2023] Open
Abstract
In many neuronal types, axon initial segment (AIS) geometry critically influences neuronal excitability. Interestingly, the axon of rat SNc dopaminergic (DA) neurons displays a highly variable location and most often arises from an axon-bearing dendrite (ABD). We combined current-clamp somatic and dendritic recordings, outside-out recordings of dendritic sodium and potassium currents, morphological reconstructions and multicompartment modeling on male and female rat SNc DA neurons to determine cell-to-cell variations in AIS and ABD geometry, and their influence on neuronal output (spontaneous pacemaking frequency, action potential [AP] shape). Both AIS and ABD geometries were found to be highly variable from neuron to neuron. Surprisingly, we found that AP shape and pacemaking frequency were independent of AIS geometry. Modeling realistic morphological and biophysical variations helped us clarify this result: in SNc DA neurons, the complexity of the ABD combined with its excitability predominantly define pacemaking frequency and AP shape, such that large variations in AIS geometry negligibly affect neuronal output and are tolerated.SIGNIFICANCE STATEMENT In many neuronal types, axon initial segment (AIS) geometry critically influences neuronal excitability. In the current study, we describe large cell-to-cell variations in AIS length or distance from the soma in rat substantia nigra pars compacta dopaminergic neurons. Using neuronal reconstruction and electrophysiological recordings, we show that this morphological variability does not seem to affect their electrophysiological output, as neither action potential properties nor pacemaking frequency is correlated with AIS morphology. Realistic multicompartment modeling suggests that this robustness to AIS variation is mainly explained by the complexity and excitability of the somatodendritic compartment.
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39
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Alpizar SA, Baker AL, Gulledge AT, Hoppa MB. Loss of Neurofascin-186 Disrupts Alignment of AnkyrinG Relative to Its Binding Partners in the Axon Initial Segment. Front Cell Neurosci 2019; 13:1. [PMID: 30723396 PMCID: PMC6349729 DOI: 10.3389/fncel.2019.00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/07/2019] [Indexed: 12/14/2022] Open
Abstract
The axon initial segment (AIS) is a specialized region within the proximal portion of the axon that initiates action potentials thanks in large part to an enrichment of sodium channels. The scaffolding protein ankyrinG (AnkG) is essential for the recruitment of sodium channels as well as several other intracellular and extracellular proteins to the AIS. In the present study, we explore the role of the cell adhesion molecule (CAM) neurofascin-186 (NF-186) in arranging the individual molecular components of the AIS in cultured rat hippocampal neurons. Using a CRISPR depletion strategy to ablate NF expression, we found that the loss of NF selectively perturbed AnkG accumulation and its relative proximal distribution within the AIS. We found that the overexpression of sodium channels could restore AnkG accumulation, but not its altered distribution within the AIS without NF present. We go on to show that although the loss of NF altered AnkG distribution, sodium channel function within the AIS remained normal. Taken together, these results demonstrate that the regulation of AnkG and sodium channel accumulation within the AIS can occur independently of one another, potentially mediated by other binding partners such as NF.
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Affiliation(s)
- Scott A Alpizar
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
| | - Arielle L Baker
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Michael B Hoppa
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
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40
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León-Espinosa G, Antón-Fernández A, Tapia-González S, DeFelipe J, Muñoz A. Modifications of the axon initial segment during the hibernation of the Syrian hamster. Brain Struct Funct 2018; 223:4307-4321. [PMID: 30219944 DOI: 10.1007/s00429-018-1753-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 09/09/2018] [Indexed: 02/07/2023]
Abstract
Mammalian hibernation is a natural process in which the brain undergoes profound adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. In addition to a virtual cessation of neural and metabolic activity, these changes include a decrease in adult neurogenesis; the retraction of neuronal dendritic trees; changes in dendritic spines and synaptic connections; fragmentation of the Golgi apparatus; and the phosphorylation of the microtubule-associated protein tau. Furthermore, alterations of microglial cells also occur in torpor. Importantly, all of these changes are rapidly and fully reversed when the animals arouse from torpor state, with no apparent brain damage occurring. Thus, hibernating animals are excellent natural models to study different aspects of brain plasticity. The axon initial segment (AIS) is critical for the initiation of action potentials in neurons and is an efficient site for the regulation of neural activity. This specialized structure-characterized by the expression of different types of ion channels and adhesion, scaffolding and cytoskeleton proteins-is subjected to morpho-functional plastic changes upon variations in neural activity or in pathological conditions. Here, we used immunocytochemistry and 3D confocal microscopy reconstruction techniques to measure the possible morphological differences in the AIS of neocortical (layers II-III and V) and hippocampal (CA1) neurons during the hibernation of the Syrian hamster. Our results indicate that the general integrity of the AIS is resistant to the ischemia/hypoxia conditions that are characteristic of the torpor phase of hibernation. In addition, the length of the AIS significantly increased in all the regions studied-by about 16-20% in torpor animals compared to controls, suggesting the existence of compensatory mechanisms in response to a decrease in neuronal activity during the torpor phase of hibernation. Furthermore, in double-labeling experiment, we found that the AIS in layer V of torpid animals was longer in neurons expressing phospho-tau than in those not labeled for phospho-tau. This suggests that AIS plastic changes were more marked in phospho-tau accumulating neurons. Overall, the results further emphasize that mammalian hibernation is a good physiological model to study AIS plasticity mechanisms in non-pathological conditions.
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Affiliation(s)
- Gonzalo León-Espinosa
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,Facultad de Farmacia, Universidad San Pablo CEU, Madrid, Spain
| | - Alejandro Antón-Fernández
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Silvia Tapia-González
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Javier DeFelipe
- Instituto Cajal, CSIC, Madrid, Spain.,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain.,CIBERNED, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, Madrid, Spain
| | - Alberto Muñoz
- Instituto Cajal, CSIC, Madrid, Spain. .,Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica (CTB), Universidad Politécnica de Madrid, Pozuelo de Alarcón, 28223, Madrid, Spain. .,Departamento de Biología Celular, Universidad Complutense, Madrid, Spain.
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41
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42
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Schlüter A, Del Turco D, Deller T, Gutzmann A, Schultz C, Engelhardt M. Structural Plasticity of Synaptopodin in the Axon Initial Segment during Visual Cortex Development. Cereb Cortex 2018; 27:4662-4675. [PMID: 28922860 DOI: 10.1093/cercor/bhx208] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Indexed: 12/12/2022] Open
Abstract
The axon initial segment (AIS) is essential for action potential generation. Recently, the AIS was identified as a site of neuronal plasticity. A subpopulation of AIS in cortical principal neurons contains stacks of endoplasmic reticulum (ER) forming the cisternal organelle (CO). The function of this organelle is poorly understood, but roles in local Ca2+-trafficking and AIS plasticity are discussed. To investigate whether the presence and/or the size of COs are linked to the development and maturation of AIS of cortical neurons, we analyzed the relationship between COs and the AIS during visual cortex development under control and visual deprivation conditions. In wildtype mice, immunolabeling for synaptopodin, ankyrin-G, and ßIV-spectrin were employed to label COs and the AIS, respectively. Dark rearing resulted in an increase in synaptopodin cluster sizes, suggesting a homeostatic function of the CO in this cellular compartment. In line with this observation, synaptopodin-deficient mice lacking the CO showed AIS shortening in the dark. Collectively, these data demonstrate that the CO is an essential part of the AIS machinery required for AIS plasticity during a critical developmental period of the visual cortex.
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Affiliation(s)
- Annabelle Schlüter
- Institute of Neuroanatomy, Centre for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str. 13-17, 68167 Mannheim, Germany.,Department of Neurobiology, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Annika Gutzmann
- Institute of Neuroanatomy, Centre for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str. 13-17, 68167 Mannheim, Germany
| | - Christian Schultz
- Institute of Neuroanatomy, Centre for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str. 13-17, 68167 Mannheim, Germany
| | - Maren Engelhardt
- Institute of Neuroanatomy, Centre for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str. 13-17, 68167 Mannheim, Germany
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43
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Ali Rodriguez R, Joya C, Hines RM. Common Ribs of Inhibitory Synaptic Dysfunction in the Umbrella of Neurodevelopmental Disorders. Front Mol Neurosci 2018; 11:132. [PMID: 29740280 PMCID: PMC5928253 DOI: 10.3389/fnmol.2018.00132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/03/2018] [Indexed: 01/06/2023] Open
Abstract
The term neurodevelopmental disorder (NDD) is an umbrella term used to group together a heterogeneous class of disorders characterized by disruption in cognition, emotion, and behavior, early in the developmental timescale. These disorders are heterogeneous, yet they share common behavioral symptomatology as well as overlapping genetic contributors, including proteins involved in the formation, specialization, and function of synaptic connections. Advances may arise from bridging the current knowledge on synapse related factors indicated from both human studies in NDD populations, and in animal models. Mounting evidence has shown a link to inhibitory synapse formation, specialization, and function among Autism, Angelman, Rett and Dravet syndromes. Inhibitory signaling is diverse, with numerous subtypes of inhibitory interneurons, phasic and tonic modes of inhibition, and the molecular and subcellular diversity of GABAA receptors. We discuss common ribs of inhibitory synapse dysfunction in the umbrella of NDD, highlighting alterations in the developmental switch to inhibitory GABA, dysregulation of neuronal activity patterns by parvalbumin-positive interneurons, and impaired tonic inhibition. Increasing our basic understanding of inhibitory synapses, and their role in NDDs is likely to produce significant therapeutic advances in behavioral symptom alleviation for interrelated NDDs.
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Affiliation(s)
- Rachel Ali Rodriguez
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Christina Joya
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Rochelle M Hines
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
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Lorenz-Guertin JM, Jacob TC. GABA type a receptor trafficking and the architecture of synaptic inhibition. Dev Neurobiol 2018; 78:238-270. [PMID: 28901728 PMCID: PMC6589839 DOI: 10.1002/dneu.22536] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/21/2022]
Abstract
Ubiquitous expression of GABA type A receptors (GABAA R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABAA Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABAA R function. Here we review the current understanding of how GABAA Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABAA R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABAA R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
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45
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Sriperumbudur KK, Pau HW, van Rienen U. Effect of Tissue Heterogeneity on the Transmembrane Potential of Type-1 Spiral Ganglion Neurons: A Simulation Study. IEEE Trans Biomed Eng 2018; 65:658-668. [DOI: 10.1109/tbme.2017.2700361] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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46
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Berger SL, Leo-Macias A, Yuen S, Khatri L, Pfennig S, Zhang Y, Agullo-Pascual E, Caillol G, Zhu MS, Rothenberg E, Melendez-Vasquez CV, Delmar M, Leterrier C, Salzer JL. Localized Myosin II Activity Regulates Assembly and Plasticity of the Axon Initial Segment. Neuron 2018; 97:555-570.e6. [PMID: 29395909 PMCID: PMC5805619 DOI: 10.1016/j.neuron.2017.12.039] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 08/24/2017] [Accepted: 12/22/2017] [Indexed: 01/08/2023]
Abstract
The axon initial segment (AIS) is the site of action potential generation and a locus of activity-dependent homeostatic plasticity. A multimeric complex of sodium channels, linked via a cytoskeletal scaffold of ankyrin G and beta IV spectrin to submembranous actin rings, mediates these functions. The mechanisms that specify the AIS complex to the proximal axon and underlie its plasticity remain poorly understood. Here we show phosphorylated myosin light chain (pMLC), an activator of contractile myosin II, is highly enriched in the assembling and mature AIS, where it associates with actin rings. MLC phosphorylation and myosin II contractile activity are required for AIS assembly, and they regulate the distribution of AIS components along the axon. pMLC is rapidly lost during depolarization, destabilizing actin and thereby providing a mechanism for activity-dependent structural plasticity of the AIS. Together, these results identify pMLC/myosin II activity as a common link between AIS assembly and plasticity.
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Affiliation(s)
- Stephen L Berger
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - Stephanie Yuen
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Latika Khatri
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Sylvia Pfennig
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Yanqing Zhang
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - Ghislaine Caillol
- Aix Marseille Université, CNRS, INP UMR7051, 13344 Cedex 15, Marseille, France
| | - Min-Sheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal and Disease Study, Nanjing University, Nanjing 210061, China
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Carmen V Melendez-Vasquez
- Department of Biological Sciences, Hunter College, New York, NY 10065, USA; Department of Molecular, Cellular, and Developmental Biology, The Graduate Center, The City University of New York, NY 10016, USA
| | - Mario Delmar
- Division of Cardiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - James L Salzer
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA.
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47
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Saha R, Kriebel M, Volkmer H, Richter-Levin G, Albrecht A. Neurofascin Knock Down in the Basolateral Amygdala Mediates Resilience of Memory and Plasticity in the Dorsal Dentate Gyrus Under Stress. Mol Neurobiol 2018; 55:7317-7326. [DOI: 10.1007/s12035-018-0930-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/24/2018] [Indexed: 11/24/2022]
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48
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The Axon Initial Segment: An Updated Viewpoint. J Neurosci 2018; 38:2135-2145. [PMID: 29378864 DOI: 10.1523/jneurosci.1922-17.2018] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 01/20/2018] [Accepted: 01/25/2018] [Indexed: 12/20/2022] Open
Abstract
At the base of axons sits a unique compartment called the axon initial segment (AIS). The AIS generates and shapes the action potential before it is propagated along the axon. Neuronal excitability thus depends crucially on the AIS composition and position, and these adapt to developmental and physiological conditions. The AIS also demarcates the boundary between the somatodendritic and axonal compartments. Recent studies have brought insights into the molecular architecture of the AIS and how it regulates protein trafficking. This Viewpoints article summarizes current knowledge about the AIS and highlights future challenges in understanding this key actor of neuronal physiology.
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49
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Abstract
Schizophrenia is a complex disorder lacking an effective treatment option for the pervasive and debilitating cognitive impairments experienced by patients. Working memory is a core cognitive function impaired in schizophrenia that depends upon activation of distributed neural network, including the circuitry of the dorsolateral prefrontal cortex (DLPFC). Accordingly, individuals diagnosed with schizophrenia show reduced DLPFC activation while performing working-memory tasks. This lower DLPFC activation appears to be an integral part of the disease pathophysiology, and not simply a reflection of poor performance. Thus, the cellular and circuitry alterations that underlie lower DLPFC neuronal activity in schizophrenia must be determined in order to identify appropriate therapeutic targets. Studies using human postmortem brain tissue provide a robust way to investigate and characterize these cellular and circuitry alterations at multiple levels of resolution, and such studies provide essential information that cannot be obtained either through in vivo studies in humans or through experimental animal models. Studies examining neuronal morphology, protein expression and localization, and transcript levels indicate that a microcircuit composed of excitatory pyramidal cells and inhibitory interneurons containing the calcium-binding protein parvalbumin is altered in the DLPFC of subjects with schizophrenia and likely contributes to DLPFC dysfunction.
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Affiliation(s)
- Jill R Glausier
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States
| | - David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States.
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50
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Guo Y, Liu Z, Chen YK, Chai Z, Zhou C, Zhang Y. Neurons with Multiple Axons Have Functional Axon Initial Segments. Neurosci Bull 2017; 33:641-652. [PMID: 28828584 DOI: 10.1007/s12264-017-0169-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 07/11/2017] [Indexed: 12/30/2022] Open
Abstract
Neurons grow multiple axons after treatment with glycogen synthase kinase-3 (GSK-3) inhibitors. However, whether they are electrically active is not known. Here, we examined the role of multiple axons as electrophysiological components during neuronal firing. Combining pharmacological, immunofluorescence, and electrophysiological methods, we found that more neurons had multiple axon initial segments (AISs) after inhibition of GSK-3 activity with SB415286. The multiple AISs induced by GSK-3 inhibition were enriched with voltage-gated sodium channels. The depolarization rate of the multiple-AIS neurons was increased, but their action potential threshold and half-width were normal. By calculating derivatives of the action-potential rising phase, an extra d2 V/dt 2 peak from the extra AIS was distinguished; this indicated that the extra AIS fired ahead of the soma and increased the rate of depolarization. Our study demonstrates that the multiple axons induced by GSK-3 inhibition have AIS structures that are electrically active, and provides insight for axon and AIS studies.
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Affiliation(s)
- Yu Guo
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China
| | - Zhuo Liu
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China.,Department of Forensic Science, People's Public Security University of China, Beijing, 100038, China
| | - Yi-Kun Chen
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China
| | - Zhen Chai
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China
| | - Chen Zhou
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China.
| | - Yan Zhang
- State Key Laboratory of Membrane Biology, College of Life Sciences, Peking University, PKU-IDG/McGovern Institute for Brain Research, Beijing, 100871, China.
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