1
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Moretti J, Rodger J. Working toward an integrated plasticity/network framework for repetitive transcranial magnetic stimulation to inform tailored treatments. Neural Regen Res 2024; 19:1423-1424. [PMID: 38051878 PMCID: PMC10883519 DOI: 10.4103/1673-5374.387990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 09/28/2023] [Indexed: 12/07/2023] Open
Affiliation(s)
- Jessica Moretti
- Experimental and Regenerative Neurosciences, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
- Brain Plasticity Lab, Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia
| | - Jennifer Rodger
- Experimental and Regenerative Neurosciences, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
- Brain Plasticity Lab, Perron Institute for Neurological and Translational Science, Nedlands, WA, Australia
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2
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Osso LA, Hughes EG. Dynamics of mature myelin. Nat Neurosci 2024:10.1038/s41593-024-01642-2. [PMID: 38773349 DOI: 10.1038/s41593-024-01642-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/05/2024] [Indexed: 05/23/2024]
Abstract
Myelin, which is produced by oligodendrocytes, insulates axons to facilitate rapid and efficient action potential propagation in the central nervous system. Traditionally viewed as a stable structure, myelin is now known to undergo dynamic modulation throughout life. This Review examines these dynamics, focusing on two key aspects: (1) the turnover of myelin, involving not only the renewal of constituents but the continuous wholesale replacement of myelin membranes; and (2) the structural remodeling of pre-existing, mature myelin, a newly discovered form of neural plasticity that can be stimulated by external factors, including neuronal activity, behavioral experience and injury. We explore the mechanisms regulating these dynamics and speculate that myelin remodeling could be driven by an asymmetry in myelin turnover or reactivation of pathways involved in myelin formation. Finally, we outline how myelin remodeling could have profound impacts on neural function, serving as an integral component of behavioral adaptation.
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Affiliation(s)
- Lindsay A Osso
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ethan G Hughes
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
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3
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Mercier O, Quilichini PP, Magalon K, Gil F, Ghestem A, Richard F, Boudier T, Cayre M, Durbec P. Transient demyelination causes long-term cognitive impairment, myelin alteration and network synchrony defects. Glia 2024; 72:960-981. [PMID: 38363046 DOI: 10.1002/glia.24513] [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: 05/17/2023] [Revised: 01/26/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
In the adult brain, activity-dependent myelin plasticity is required for proper learning and memory consolidation. Myelin loss, alteration, or even subtle structural modifications can therefore compromise the network activity, leading to functional impairment. In multiple sclerosis, spontaneous myelin repair process is possible, but it is heterogeneous among patients, sometimes leading to functional recovery, often more visible at the motor level than at the cognitive level. In cuprizone-treated mouse model, massive brain demyelination is followed by spontaneous and robust remyelination. However, reformed myelin, although functional, may not exhibit the same morphological characteristics as developmental myelin, which can have an impact on the activity of neural networks. In this context, we used the cuprizone-treated mouse model to analyze the structural, functional, and cognitive long-term effects of transient demyelination. Our results show that an episode of demyelination induces despite remyelination long-term cognitive impairment, such as deficits in spatial working memory, social memory, cognitive flexibility, and hyperactivity. These deficits were associated with a reduction in myelin content in the medial prefrontal cortex (mPFC) and hippocampus (HPC), as well as structural myelin modifications, suggesting that the remyelination process may be imperfect in these structures. In vivo electrophysiological recordings showed that the demyelination episode altered the synchronization of HPC-mPFC activity, which is crucial for memory processes. Altogether, our data indicate that the myelin repair process following transient demyelination does not allow the complete recovery of the initial myelin properties in cortical structures. These subtle modifications alter network features, leading to prolonged cognitive deficits in mice.
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Affiliation(s)
- Océane Mercier
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | - Pascale P Quilichini
- U1106 after INS, Aix Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France
| | - Karine Magalon
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | - Florian Gil
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | - Antoine Ghestem
- U1106 after INS, Aix Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France
| | - Fabrice Richard
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | - Thomas Boudier
- Aix Marseille Univ, Turing Centre for Living Systems, Marseille, France
| | - Myriam Cayre
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
| | - Pascale Durbec
- UMR7288 after IBDM, Aix Marseille Univ, CNRS, IBDM, Marseille, France
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4
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Khelfaoui H, Ibaceta-Gonzalez C, Angulo MC. Functional myelin in cognition and neurodevelopmental disorders. Cell Mol Life Sci 2024; 81:181. [PMID: 38615095 PMCID: PMC11016012 DOI: 10.1007/s00018-024-05222-2] [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: 12/08/2023] [Revised: 03/18/2024] [Accepted: 03/30/2024] [Indexed: 04/15/2024]
Abstract
In vertebrates, oligodendrocytes (OLs) are glial cells of the central nervous system (CNS) responsible for the formation of the myelin sheath that surrounds the axons of neurons. The myelin sheath plays a crucial role in the transmission of neuronal information by promoting the rapid saltatory conduction of action potentials and providing neurons with structural and metabolic support. Saltatory conduction, first described in the peripheral nervous system (PNS), is now generally recognized as a universal evolutionary innovation to respond quickly to the environment: myelin helps us think and act fast. Nevertheless, the role of myelin in the central nervous system, especially in the brain, may not be primarily focused on accelerating conduction speed but rather on ensuring precision. Its principal function could be to coordinate various neuronal networks, promoting their synchronization through oscillations (or rhythms) relevant for specific information processing tasks. Interestingly, myelin has been directly involved in different types of cognitive processes relying on brain oscillations, and myelin plasticity is currently considered to be part of the fundamental mechanisms for memory formation and maintenance. However, despite ample evidence showing the involvement of myelin in cognition and neurodevelopmental disorders characterized by cognitive impairments, the link between myelin, brain oscillations, cognition and disease is not yet fully understood. In this review, we aim to highlight what is known and what remains to be explored to understand the role of myelin in high order brain processes.
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Affiliation(s)
- Hasni Khelfaoui
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, 75014, Paris, France
| | - Cristobal Ibaceta-Gonzalez
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, 75014, Paris, France
| | - Maria Cecilia Angulo
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, 75014, Paris, France.
- GHU-PARIS Psychiatrie Et Neurosciences, Hôpital Sainte Anne, 75014, Paris, France.
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5
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Asadian N, Aprico A, Chen M, Yuen D, Johnston APR, Kilpatrick TJ, Binder MD. The therapeutic effect of GAS6 in remyelination is dependent upon Tyro3. Glia 2024. [PMID: 38572807 DOI: 10.1002/glia.24534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 03/26/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
Multiple sclerosis is an autoimmune disease of the central nervous system (CNS) characterized by demyelination, axonal damage and, for the majority of people, a decline in neurological function in the long-term. Remyelination could assist in the protection of axons and their functional recovery, but such therapies are not, as yet, available. The TAM (Tyro3, Axl, and MERTK) receptor ligand GAS6 potentiates myelination in vitro and promotes recovery in pre-clinical models of MS. However, it has remained unclear which TAM receptor is responsible for transducing this effect and whether post-translational modification of GAS6 is required. In this study, we show that the promotion of myelination requires post-translational modification of the GLA domain of GAS6 via vitamin K-dependent γ-carboxylation. We also confirmed that the intracerebroventricular provision of GAS6 for 2 weeks to demyelinated wild-type (WT) mice challenged with cuprizone increased the density of myelinated axons in the corpus callosum by over 2-fold compared with vehicle control. Conversely, the provision of GAS6 to Tyro3 KO mice did not significantly improve the density of myelinated axons. The improvement in remyelination following the provision of GAS6 to WT mice was also accompanied by an increased density of CC1+ve mature oligodendrocytes compared with vehicle control, whereas this improvement was not observed in the absence of Tyro3. This effect occurs independent of any influence on microglial activation. This work therefore establishes that the remyelinative activity of GAS6 is dependent on Tyro3 and includes potentiation of oligodendrocyte numbers.
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Affiliation(s)
- Negar Asadian
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Andrea Aprico
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Moore Chen
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Daniel Yuen
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Angus P R Johnston
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Trevor J Kilpatrick
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Michele D Binder
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
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6
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Santos E, Huffman WC, Fields RD. Recovery of node of ranvier structure in optic nerve under visual deprivation. Neurosci Res 2024:S0168-0102(24)00050-6. [PMID: 38554941 DOI: 10.1016/j.neures.2024.03.005] [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: 12/11/2023] [Revised: 03/01/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
Neural activity can increase the length of nodes of Ranvier (NOR) and slow impulse transmission; however, little is known about the biologically and clinically important recovery process. Sensory deprivation promotes neural plasticity in many phenomena, raising the question of whether recovery of NOR morphology is influenced by sensory deprivation. The results show that NOR gap length recovery in mouse optic nerve was not affected significantly by binocular visual deprivation imposed by maintaining mice in 24 hr dark for 30 days compared to mice recovering under normal visual experience. The findings provide insight into the cellular mechanism of NOR plasticity.
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Affiliation(s)
- Erin Santos
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH,USA
| | - William C Huffman
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH,USA
| | - R Douglas Fields
- Nervous System Development and Plasticity Section, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH,USA.
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7
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Iyer M, Kantarci H, Cooper MH, Ambiel N, Novak SW, Andrade LR, Lam M, Jones G, Münch AE, Yu X, Khakh BS, Manor U, Zuchero JB. Oligodendrocyte calcium signaling promotes actin-dependent myelin sheath extension. Nat Commun 2024; 15:265. [PMID: 38177161 PMCID: PMC10767123 DOI: 10.1038/s41467-023-44238-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 12/05/2023] [Indexed: 01/06/2024] Open
Abstract
Myelin is essential for rapid nerve signaling and is increasingly found to play important roles in learning and in diverse diseases of the CNS. Morphological parameters of myelin such as sheath length are thought to precisely tune conduction velocity, but the mechanisms controlling sheath morphology are poorly understood. Local calcium signaling has been observed in nascent myelin sheaths and can be modulated by neuronal activity. However, the role of calcium signaling in sheath formation remains incompletely understood. Here, we use genetic tools to attenuate oligodendrocyte calcium signaling during myelination in the developing mouse CNS. Surprisingly, genetic calcium attenuation does not grossly affect the number of myelinated axons or myelin thickness. Instead, calcium attenuation causes myelination defects resulting in shorter, dysmorphic sheaths. Mechanistically, calcium attenuation reduces actin filaments in oligodendrocytes, and an intact actin cytoskeleton is necessary and sufficient to achieve accurate myelin morphology. Together, our work reveals a cellular mechanism required for accurate CNS myelin formation and may provide mechanistic insight into how oligodendrocytes respond to neuronal activity to sculpt and refine myelin sheaths.
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Affiliation(s)
- Manasi Iyer
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Husniye Kantarci
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Madeline H Cooper
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Nicholas Ambiel
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Sammy Weiser Novak
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Leonardo R Andrade
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Mable Lam
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Graham Jones
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Alexandra E Münch
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Xinzhu Yu
- Department of Molecular and Integrative Physiology, Beckman Institute, University of Illinois at Urbana-, Champaign, IL, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, USA
- Department of Cell and Developmental Biology, University of California, San Diego, San Diego, CA, USA
| | - J Bradley Zuchero
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA.
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8
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Ferreira SA, Pinto N, Serrenho I, Pato MV, Baltazar G. Contribution of glial cells to the neuroprotective effects triggered by repetitive magnetic stimulation: a systematic review. Neural Regen Res 2024; 19:116-123. [PMID: 37488852 PMCID: PMC10479834 DOI: 10.4103/1673-5374.374140] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/27/2023] [Accepted: 03/28/2023] [Indexed: 07/26/2023] Open
Abstract
Repetitive transcranial magnetic stimulation has been increasingly studied in different neurological diseases, and although most studies focus on its effects on neuronal cells, the contribution of non-neuronal cells to the improvement triggered by repetitive transcranial magnetic stimulation in these diseases has been increasingly suggested. To systematically review the effects of repetitive magnetic stimulation on non-neuronal cells two online databases, Web of Science and PubMed were searched for the effects of high-frequency-repetitive transcranial magnetic stimulation, low-frequency-repetitive transcranial magnetic stimulation, intermittent theta-burst stimulation, continuous theta-burst stimulation, or repetitive magnetic stimulation on non-neuronal cells in models of disease and in unlesioned animals or cells. A total of 52 studies were included. The protocol more frequently used was high-frequency-repetitive magnetic stimulation, and in models of disease, most studies report that high-frequency-repetitive magnetic stimulation led to a decrease in astrocyte and microglial reactivity, a decrease in the release of pro-inflammatory cytokines, and an increase of oligodendrocyte proliferation. The trend towards decreased microglial and astrocyte reactivity as well as increased oligodendrocyte proliferation occurred with intermittent theta-burst stimulation and continuous theta-burst stimulation. Few papers analyzed the low-frequency-repetitive transcranial magnetic stimulation protocol, and the parameters evaluated were restricted to the study of astrocyte reactivity and release of pro-inflammatory cytokines, reporting the absence of effects on these parameters. In what concerns the use of magnetic stimulation in unlesioned animals or cells, most articles on all four types of stimulation reported a lack of effects. It is also important to point out that the studies were developed mostly in male rodents, not evaluating possible differential effects of repetitive transcranial magnetic stimulation between sexes. This systematic review supports that through modulation of glial cells repetitive magnetic stimulation contributes to the neuroprotection or repair in various neurological disease models. However, it should be noted that there are still few articles focusing on the impact of repetitive magnetic stimulation on non-neuronal cells and most studies did not perform in-depth analyses of the effects, emphasizing the need for more studies in this field.
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Affiliation(s)
- Susana A. Ferreira
- Centro de Investigação em Ciências da Saúde (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal
| | - Nuno Pinto
- Centro de Investigação em Ciências da Saúde (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal
- Faculdade de Ciências da Saúde, Universidade da Beira Interior, Covilhã, Portugal
- GRUBI-Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
| | - Inês Serrenho
- Centro de Investigação em Ciências da Saúde (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal
| | - Maria Vaz Pato
- Centro de Investigação em Ciências da Saúde (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal
- Faculdade de Ciências da Saúde, Universidade da Beira Interior, Covilhã, Portugal
- GRUBI-Systematic Reviews Group, University of Beira Interior, Covilhã, Portugal
| | - Graça Baltazar
- Centro de Investigação em Ciências da Saúde (CICS-UBI), Universidade da Beira Interior, Covilhã, Portugal
- Faculdade de Ciências da Saúde, Universidade da Beira Interior, Covilhã, Portugal
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9
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Louie AY, Rund LA, Komiyama-Kasai KA, Weisenberger KE, Stanke KL, Larsen RJ, Leyshon BJ, Kuchan MJ, Das T, Steelman AJ. A hydrolyzed lipid blend diet promotes myelination in neonatal piglets in a region and concentration-dependent manner. J Neurosci Res 2023; 101:1864-1883. [PMID: 37737490 DOI: 10.1002/jnr.25243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/11/2023] [Accepted: 09/04/2023] [Indexed: 09/23/2023]
Abstract
The impact of early life nutrition on myelin development is of interest given that cognitive and behavioral function depends on proper myelination. Evidence shows that myelination can be altered by dietary lipid, but most of these studies have been performed in the context of disease or impairment. Here, we assessed the effects of lipid blends containing various levels of a hydrolyzed fat (HF) system on myelination in healthy piglets. Piglets were sow-reared, fed a control diet, or a diet containing 12%, 25%, or 53% HF consisting of cholesterol, fatty acids, monoglycerides, and phospholipid from lecithin. At postnatal day 28/29, magnetic resonance imaging (MRI) was performed to assess changes to brain development, followed by brain collection for microscopic analyses of myelin in targeted regions using CLARITY tissue clearing, immunohistochemistry, and electron microscopy techniques. Sow-reared piglets exhibited the highest overall brain white matter volume by MRI. However, a 25% HF diet resulted in the greatest total myelin density in the prefrontal cortex based on 3D modeling analysis of myelinated filaments. Nodal gap length and g-ratio were inversely correlated with percentage of HF in the corpus callosum, as well as in the PFC and internal capsule for g-ratio, indicating that a 53% HF diet resulted in the thickest myelin per axon and a 0% HF control diet the thinnest in specific brain regions. These findings indicate that HF promoted myelination in the neonatal piglet in a region- and concentration-dependent manner.
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Affiliation(s)
- Allison Y Louie
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Laurie A Rund
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Karin A Komiyama-Kasai
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Kelsie E Weisenberger
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Kayla L Stanke
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Ryan J Larsen
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Psychology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | | | | | - Tapas Das
- Abbott Nutrition, Columbus, Ohio, USA
| | - Andrew J Steelman
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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10
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Voelker P, Weible AP, Niell CM, Rothbart MK, Posner MI. Molecular Mechanisms for Changing Brain Connectivity in Mice and Humans. Int J Mol Sci 2023; 24:15840. [PMID: 37958822 PMCID: PMC10648558 DOI: 10.3390/ijms242115840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
The goal of this study was to examine commonalities in the molecular basis of learning in mice and humans. In previous work we have demonstrated that the anterior cingulate cortex (ACC) and hippocampus (HC) are involved in learning a two-choice visuospatial discrimination task. Here, we began by looking for candidate genes upregulated in mouse ACC and HC with learning. We then determined which of these were also upregulated in mouse blood. Finally, we used RT-PCR to compare candidate gene expression in mouse blood with that from humans following one of two forms of learning: a working memory task (network training) or meditation (a generalized training shown to change many networks). Two genes were upregulated in mice following learning: caspase recruitment domain-containing protein 6 (Card6) and inosine monophosphate dehydrogenase 2 (Impdh2). The Impdh2 gene product catalyzes the first committed step of guanine nucleotide synthesis and is tightly linked to cell proliferation. The Card6 gene product positively modulates signal transduction. In humans, Card6 was significantly upregulated, and Impdh2 trended toward upregulation with training. These genes have been shown to regulate pathways that influence nuclear factor kappa B (NF-κB), a factor previously found to be related to enhanced synaptic function and learning.
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Affiliation(s)
- Pascale Voelker
- Department of Psychology, University of Oregon, Eugene, OR 97403, USA (M.I.P.)
| | - Aldis P. Weible
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; (A.P.W.); (C.M.N.)
| | - Cristopher M. Niell
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; (A.P.W.); (C.M.N.)
- Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - Mary K. Rothbart
- Department of Psychology, University of Oregon, Eugene, OR 97403, USA (M.I.P.)
| | - Michael I. Posner
- Department of Psychology, University of Oregon, Eugene, OR 97403, USA (M.I.P.)
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA; (A.P.W.); (C.M.N.)
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11
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Quintela-López T, Lezmy J. Homeostatic plasticity of axonal excitable sites in Alzheimer's disease. Front Neurosci 2023; 17:1277251. [PMID: 37937068 PMCID: PMC10626477 DOI: 10.3389/fnins.2023.1277251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/06/2023] [Indexed: 11/09/2023] Open
Affiliation(s)
| | - Jonathan Lezmy
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
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12
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Koskinen MK, Laine M, Abdollahzadeh A, Gigliotta A, Mazzini G, Journée S, Alenius V, Trontti K, Tohka J, Hyytiä P, Sierra A, Hovatta I. Node of Ranvier remodeling in chronic psychosocial stress and anxiety. Neuropsychopharmacology 2023; 48:1532-1540. [PMID: 36949148 PMCID: PMC10425340 DOI: 10.1038/s41386-023-01568-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 02/07/2023] [Accepted: 03/03/2023] [Indexed: 03/24/2023]
Abstract
Differential expression of myelin-related genes and changes in myelin thickness have been demonstrated in mice after chronic psychosocial stress, a risk factor for anxiety disorders. To determine whether and how stress affects structural remodeling of nodes of Ranvier, another form of myelin plasticity, we developed a 3D reconstruction analysis of node morphology in C57BL/6NCrl and DBA/2NCrl mice. We identified strain-dependent effects of chronic social defeat stress on node morphology in the medial prefrontal cortex (mPFC) gray matter, including shortening of paranodes in C57BL/6NCrl stress-resilient and shortening of node gaps in DBA/2NCrl stress-susceptible mice compared to controls. Neuronal activity has been associated with changes in myelin thickness. To investigate whether neuronal activation is a mechanism influencing also node of Ranvier morphology, we used DREADDs to repeatedly activate the ventral hippocampus-to-mPFC pathway. We found reduced anxiety-like behavior and shortened paranodes specifically in stimulated, but not in the nearby non-stimulated axons. Altogether, our data demonstrate (1) nodal remodeling of the mPFC gray matter axons after chronic stress and (2) axon-specific regulation of paranodes in response to repeated neuronal activity in an anxiety-associated pathway. Nodal remodeling may thus contribute to aberrant circuit function associated with anxiety disorders.
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Affiliation(s)
- Maija-Kreetta Koskinen
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Mikaela Laine
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Ali Abdollahzadeh
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Adrien Gigliotta
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Giulia Mazzini
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Sarah Journée
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Varpu Alenius
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Kalevi Trontti
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jussi Tohka
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Petri Hyytiä
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Alejandra Sierra
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Iiris Hovatta
- SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Neuroscience Center, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland.
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13
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Iyer M, Kantarci H, Ambiel N, Novak SW, Andrade LR, Lam M, Münch AE, Yu X, Khakh BS, Manor U, Zuchero JB. Oligodendrocyte calcium signaling sculpts myelin sheath morphology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.11.536299. [PMID: 37090556 PMCID: PMC10120717 DOI: 10.1101/2023.04.11.536299] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Myelin is essential for rapid nerve signaling and is increasingly found to play important roles in learning and in diverse diseases of the CNS. Morphological parameters of myelin such as sheath length and thickness are regulated by neuronal activity and can precisely tune conduction velocity, but the mechanisms controlling sheath morphology are poorly understood. Local calcium signaling has been observed in nascent myelin sheaths and can be modulated by neuronal activity. However, the role of calcium signaling in sheath formation and remodeling is unknown. Here, we used genetic tools to attenuate oligodendrocyte calcium signaling during active myelination in the developing mouse CNS. Surprisingly, we found that genetic calcium attenuation did not grossly affect the number of myelinated axons or myelin thickness. Instead, calcium attenuation caused striking myelination defects resulting in shorter, dysmorphic sheaths. Mechanistically, calcium attenuation reduced actin filaments in oligodendrocytes, and an intact actin cytoskeleton was necessary and sufficient to achieve accurate myelin morphology. Together, our work reveals a novel cellular mechanism required for accurate CNS myelin formation and provides mechanistic insight into how oligodendrocytes may respond to neuronal activity to sculpt myelin sheaths throughout the nervous system.
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14
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Stirling DP. Potential physiological and pathological roles for axonal ryanodine receptors. Neural Regen Res 2023; 18:756-759. [PMID: 36204832 PMCID: PMC9700104 DOI: 10.4103/1673-5374.354512] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/02/2022] [Accepted: 06/23/2022] [Indexed: 11/04/2022] Open
Abstract
Clinical disability following trauma or disease to the spinal cord often involves the loss of vital white matter elements including axons and glia. Although excessive Ca2+ is an established driver of axonal degeneration, therapeutically targeting externally sourced Ca2+ to date has had limited success in both basic and clinical studies. Contributing factors that may underlie this limited success include the complexity of the many potential sources of Ca2+ entry and the discovery that axons also contain substantial amounts of stored Ca2+ that if inappropriately released could contribute to axonal demise. Axonal Ca2+ storage is largely accomplished by the axoplasmic reticulum that is part of a continuous network of the endoplasmic reticulum that provides a major sink and source of intracellular Ca2+ from the tips of dendrites to axonal terminals. This "neuron-within-a-neuron" is positioned to rapidly respond to diverse external and internal stimuli by amplifying cytosolic Ca2+ levels and generating short and long distance regenerative Ca2+ waves through Ca2+ induced Ca2+ release. This review provides a glimpse into the molecular machinery that has been implicated in regulating ryanodine receptor mediated Ca2+ release in axons and how dysregulation and/or overstimulation of these internodal axonal signaling nanocomplexes may directly contribute to Ca2+-dependent axonal demise. Neuronal ryanodine receptors expressed in dendrites, soma, and axonal terminals have been implicated in synaptic transmission and synaptic plasticity, but a physiological role for internodal localized ryanodine receptors remains largely obscure. Plausible physiological roles for internodal ryanodine receptors and such an elaborate internodal binary membrane signaling network in axons will also be discussed.
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Affiliation(s)
- David P. Stirling
- Kentucky Spinal Cord Injury Research Center and Departments of Neurological Surgery, Anatomical Sciences and Neurobiology, Microbiology and Immunology, University of Louisville, School of Medicine, Louisville, KY, USA
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15
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Kwon J, Lee S, Jo Y, Choi M. All-optical observation on activity-dependent nanoscale dynamics of myelinated axons. NEUROPHOTONICS 2023; 10:015003. [PMID: 36699624 PMCID: PMC9868287 DOI: 10.1117/1.nph.10.1.015003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
SIGNIFICANCE In the mammalian brain, rapid conduction of neural information is supported by the myelin, the functional efficacy of which shows steep dependence on its nanoscale cytoarchitecture. Although previous in vitro studies have suggested that neural activity accompanies nanometer-scale cellular deformations, whether neural activity can dynamically remodel the myelinated axon has remained unexplored due to the technical challenge in observing its nanostructural dynamics in living tissues. AIM We aim to observe activity-dependent nanostructural dynamics of myelinated axons in a living brain tissue. APPROACH We introduced a novel all-optical approach combining a nanoscale dynamic readout based on spectral interferometry and optogenetic control of neural excitation in an acute brain slice preparation. RESULTS In response to optogenetically evoked neuronal burst firing, the myelinated axons exhibited progressive and reversible spectral redshifts, corresponding to the transient swelling at a subnanometer scale. We further revealed that the activity-dependent nanostructural dynamics was localized to the paranode. CONCLUSIONS Our all-optical studies substantiate that myelinated axon exhibits activity-dependent nanoscale swelling, which potentially serves to dynamically tune the transmission speed of neural information.
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Affiliation(s)
- Junhwan Kwon
- Sungkyunkwan University, Department of Biomedical Engineering, Suwon, Republic of Korea
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
| | - Sungho Lee
- Seoul National University, School of Biological Sciences, Seoul, Republic of Korea
- Seoul National University, The Institute of Molecular Biology and Genetics, Seoul, Republic of Korea
| | - Yongjae Jo
- Institute for Basic Science, Center for Neuroscience Imaging Research, Suwon, Republic of Korea
| | - Myunghwan Choi
- Seoul National University, School of Biological Sciences, Seoul, Republic of Korea
- Seoul National University, The Institute of Molecular Biology and Genetics, Seoul, Republic of Korea
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16
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Precise Spiking Motifs in Neurobiological and Neuromorphic Data. Brain Sci 2022; 13:brainsci13010068. [PMID: 36672049 PMCID: PMC9856822 DOI: 10.3390/brainsci13010068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/20/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
Why do neurons communicate through spikes? By definition, spikes are all-or-none neural events which occur at continuous times. In other words, spikes are on one side binary, existing or not without further details, and on the other, can occur at any asynchronous time, without the need for a centralized clock. This stands in stark contrast to the analog representation of values and the discretized timing classically used in digital processing and at the base of modern-day neural networks. As neural systems almost systematically use this so-called event-based representation in the living world, a better understanding of this phenomenon remains a fundamental challenge in neurobiology in order to better interpret the profusion of recorded data. With the growing need for intelligent embedded systems, it also emerges as a new computing paradigm to enable the efficient operation of a new class of sensors and event-based computers, called neuromorphic, which could enable significant gains in computation time and energy consumption-a major societal issue in the era of the digital economy and global warming. In this review paper, we provide evidence from biology, theory and engineering that the precise timing of spikes plays a crucial role in our understanding of the efficiency of neural networks.
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17
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Nicholson M, Wood RJ, Gonsalvez DG, Hannan AJ, Fletcher JL, Xiao J, Murray SS. Remodelling of myelinated axons and oligodendrocyte differentiation is stimulated by environmental enrichment in the young adult brain. Eur J Neurosci 2022; 56:6099-6114. [PMID: 36217300 PMCID: PMC10092722 DOI: 10.1111/ejn.15840] [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: 05/26/2022] [Revised: 09/30/2022] [Accepted: 10/05/2022] [Indexed: 12/29/2022]
Abstract
Oligodendrocyte production and myelination continues lifelong in the central nervous system (CNS), and all stages of this process can be adaptively regulated by neuronal activity. While artificial exogenous stimulation of neuronal circuits greatly enhances oligodendrocyte progenitor cell (OPC) production and increases myelination during development, the extent to which physiological stimuli replicates this is unclear, particularly in the adult CNS when the rate of new myelin addition slows. Here, we used environmental enrichment (EE) to physiologically stimulate neuronal activity for 6 weeks in 9-week-old C57BL/six male and female mice and found no increase in compact myelin in the corpus callosum or somatosensory cortex. Instead, we observed a global increase in callosal axon diameter with thicker myelin sheaths, elongated paranodes and shortened nodes of Ranvier. These findings indicate that EE induced the dynamic structural remodelling of myelinated axons. Additionally, we observed a global increase in the differentiation of OPCs and pre-myelinating oligodendroglia in the corpus callosum and somatosensory cortex. Our findings of structural remodelling of myelinated axons in response to physiological neural stimuli during young adulthood provide important insights in understanding experience-dependent myelin plasticity throughout the lifespan and provide a platform to investigate axon-myelin interactions in a physiologically relevant context.
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Affiliation(s)
- Madeline Nicholson
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Rhiannon J Wood
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - David G Gonsalvez
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia.,Department of Anatomy and Developmental Biology, Monash University, Clayton, Australia
| | - Anthony J Hannan
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia.,Florey Institute of Neuroscience and Mental Health, Parkville, Australia
| | - Jessica L Fletcher
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia.,Menzies Institute of Medical Research, University of Tasmania, Hobart, Australia
| | - Junhua Xiao
- School of Health Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia.,School of Allied Health, La Trobe University, Bundoora, Victoria, Australia
| | - Simon S Murray
- Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia.,Florey Institute of Neuroscience and Mental Health, Parkville, Australia
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18
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Abstract
Within the past decade, multiple lines of evidence have converged to identify a critical role for activity-regulated myelination in tuning the function of neural networks. In this Review, we provide an overview of accumulating evidence that activity-regulated myelination is required for brain adaptation and learning across multiple domains. We then discuss dysregulation of activity-dependent myelination in the context of neurological disease, a novel frontier with the potential to uncover new mechanisms of disease pathogenesis and to develop new therapeutic strategies. Alterations in myelination and neural network function can result from deficient myelin plasticity that impairs neurological function or from maladaptive myelination, in which intact activity-dependent myelination contributes to the disease process by promoting pathological patterns of neuronal activity. These emerging mechanisms suggest new avenues for therapeutic intervention that could more fully address the complex interactions between neurons and oligodendroglia.
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19
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Chataigner LMP, Gogou C, den Boer MA, Frias CP, Thies-Weesie DME, Granneman JCM, Heck AJR, Meijer DH, Janssen BJC. Structural insights into the contactin 1 - neurofascin 155 adhesion complex. Nat Commun 2022; 13:6607. [PMID: 36329006 PMCID: PMC9633819 DOI: 10.1038/s41467-022-34302-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Cell-surface expressed contactin 1 and neurofascin 155 control wiring of the nervous system and interact across cells to form and maintain paranodal myelin-axon junctions. The molecular mechanism of contactin 1 - neurofascin 155 adhesion complex formation is unresolved. Crystallographic structures of complexed and individual contactin 1 and neurofascin 155 binding regions presented here, provide a rich picture of how competing and complementary interfaces, post-translational glycosylation, splice differences and structural plasticity enable formation of diverse adhesion sites. Structural, biophysical, and cell-clustering analysis reveal how conserved Ig1-2 interfaces form competing heterophilic contactin 1 - neurofascin 155 and homophilic neurofascin 155 complexes whereas contactin 1 forms low-affinity clusters through interfaces on Ig3-6. The structures explain how the heterophilic Ig1-Ig4 horseshoe's in the contactin 1 - neurofascin 155 complex define the 7.4 nm paranodal spacing and how the remaining six domains enable bridging of distinct intercellular distances.
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Affiliation(s)
- Lucas M. P. Chataigner
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Christos Gogou
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Maurits A. den Boer
- grid.5477.10000000120346234Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands ,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Cátia P. Frias
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Dominique M. E. Thies-Weesie
- grid.5477.10000000120346234Van’t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute of Nanomaterials Science, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Joke C. M. Granneman
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Albert J. R. Heck
- grid.5477.10000000120346234Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands ,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Dimphna H. Meijer
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Bert J. C. Janssen
- grid.5477.10000000120346234Structural Biochemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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20
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Oligodendroglia are emerging players in several forms of learning and memory. Commun Biol 2022; 5:1148. [PMID: 36309567 PMCID: PMC9617857 DOI: 10.1038/s42003-022-04116-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 10/14/2022] [Indexed: 11/15/2022] Open
Abstract
Synaptic plasticity is the fundamental cellular mechanism of learning and memory, but recent research reveals that myelin-forming glia, oligodendrocytes (OL), are also involved. They contribute in ways that synaptic plasticity cannot, and the findings have not been integrated into the established conceptual framework used in the field of learning and memory. OLs and their progenitors are involved in long-term memory, memory consolidation, working memory, and recall in associative learning. They also contribute to short-term memory and non-associative learning by affecting synaptic transmission, intrinsic excitability of axons, and neural oscillations. Oligodendroglial involvement expands the field beyond synaptic plasticity to system-wide network function, where precise spike time arrival and neural oscillations are critical in information processing, storage, and retrieval. A Perspective highlights current evidence that supports oligodendrocytes and their progenitors’ involvement in cognition and proposes that our understanding of learning and memory can be expanded beyond the classic view of synaptic plasticity to a system-wide network function.
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21
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Osanai Y, Yamazaki R, Shinohara Y, Ohno N. Heterogeneity and regulation of oligodendrocyte morphology. Front Cell Dev Biol 2022; 10:1030486. [PMID: 36393856 PMCID: PMC9644283 DOI: 10.3389/fcell.2022.1030486] [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: 08/29/2022] [Accepted: 10/10/2022] [Indexed: 09/24/2023] Open
Abstract
Oligodendrocytes form multiple myelin sheaths in the central nervous system (CNS), which increase nerve conduction velocity and are necessary for basic and higher brain functions such as sensory function, motor control, and learning. Structures of the myelin sheath such as myelin internodal length and myelin thickness regulate nerve conduction. Various parts of the central nervous system exhibit different myelin structures and oligodendrocyte morphologies. Recent studies supported that oligodendrocytes are a heterogenous population of cells and myelin sheaths formed by some oligodendrocytes can be biased to particular groups of axons, and myelin structures are dynamically modulated in certain classes of neurons by specific experiences. Structures of oligodendrocyte/myelin are also affected in pathological conditions such as demyelinating and neuropsychiatric disorders. This review summarizes our understanding of heterogeneity and regulation of oligodendrocyte morphology concerning central nervous system regions, neuronal classes, experiences, diseases, and how oligodendrocytes are optimized to execute central nervous system functions.
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Affiliation(s)
- Yasuyuki Osanai
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC, Australia
| | - Reiji Yamazaki
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Yoshiaki Shinohara
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Yamanashi, Chuo, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
- Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, Japan
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22
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Talidou A, Frankland PW, Mabbott D, Lefebvre J. Homeostatic coordination and up-regulation of neural activity by activity-dependent myelination. NATURE COMPUTATIONAL SCIENCE 2022; 2:665-676. [PMID: 38177260 DOI: 10.1038/s43588-022-00315-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 08/10/2022] [Indexed: 01/06/2024]
Abstract
Activity-dependent myelination (ADM) is a fundamental dimension of brain plasticity through which myelin changes as a function of neural activity. Mediated by structural changes in glia, ADM notably regulates axonal conduction velocity. Yet, it remains unclear how neural activity impacts myelination to orchestrate the timing of neural signalling, and how ADM shapes neural activity. We developed a model of spiking neurons enhanced with neuron-oligodendrocyte feedback and examined the relationship between ADM and neural activity. We found that ADM implements a homeostatic gain control mechanism that enhances neural firing rates and correlations through the temporal coordination of action potentials as axon lengths increase. Stimuli engage ADM plasticity to trigger bidirectional and reversible changes in conduction delays, as may occur during learning. Furthermore, ADM was found to enhance information transmission under various types of time-varying stimuli. These results highlight the role of ADM in shaping neural activity and communication.
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Affiliation(s)
- Afroditi Talidou
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.
| | - Paul W Frankland
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Donald Mabbott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Jérémie Lefebvre
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physics, University of Ottawa, Ottawa, Ontario, Canada
- Department of Mathematics, University of Toronto, Toronto, Ontario, Canada
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23
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Bacmeister CM, Huang R, Osso LA, Thornton MA, Conant L, Chavez AR, Poleg-Polsky A, Hughes EG. Motor learning drives dynamic patterns of intermittent myelination on learning-activated axons. Nat Neurosci 2022; 25:1300-1313. [PMID: 36180791 PMCID: PMC9651929 DOI: 10.1038/s41593-022-01169-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 08/18/2022] [Indexed: 01/10/2023]
Abstract
Myelin plasticity occurs when newly formed and pre-existing oligodendrocytes remodel existing patterns of myelination. Myelin remodeling occurs in response to changes in neuronal activity and is required for learning and memory. However, the link between behavior-induced neuronal activity and circuit-specific changes in myelination remains unclear. Using longitudinal in vivo two-photon imaging and targeted labeling of learning-activated neurons in mice, we explore how the pattern of intermittent myelination is altered on individual cortical axons during learning of a dexterous reach task. We show that behavior-induced myelin plasticity is targeted to learning-activated axons and occurs in a staged response across cortical layers in the mouse primary motor cortex. During learning, myelin sheaths retract, which results in lengthening of nodes of Ranvier. Following motor learning, addition of newly formed myelin sheaths increases the number of continuous stretches of myelination. Computational modeling suggests that motor learning-induced myelin plasticity initially slows and subsequently increases axonal conduction speed. Finally, we show that both the magnitude and timing of nodal and myelin dynamics correlate with improvement of behavioral performance during motor learning. Thus, learning-induced and circuit-specific myelination changes may contribute to information encoding in neural circuits during motor learning.
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Affiliation(s)
- Clara M Bacmeister
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
- Neuroscience IDP Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Rongchen Huang
- Department of Neurosurgery, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Lindsay A Osso
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Michael A Thornton
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Lauren Conant
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Anthony R Chavez
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Alon Poleg-Polsky
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ethan G Hughes
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
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24
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Xin W, Chan JR. Motor learning revamps the myelin landscape. Nat Neurosci 2022; 25:1251-1252. [PMID: 36180789 PMCID: PMC10668869 DOI: 10.1038/s41593-022-01156-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Learning requires new oligodendrogenesis, but how myelin patterns change during learning is unclear. Bacmeister et al. show that motor learning induces phase-specific changes in myelination on behaviorally activated axons that correlate with motor performance, suggesting myelin remodeling is involved in learning.
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Affiliation(s)
- Wendy Xin
- Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA.
| | - Jonah R Chan
- Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA.
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25
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Osanai Y, Battulga B, Yamazaki R, Kouki T, Yatabe M, Mizukami H, Kobayashi K, Shinohara Y, Yoshimura Y, Ohno N. Dark Rearing in the Visual Critical Period Causes Structural Changes in Myelinated Axons in the Adult Mouse Visual Pathway. Neurochem Res 2022; 47:2815-2825. [PMID: 35933550 DOI: 10.1007/s11064-022-03689-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 06/14/2022] [Accepted: 07/12/2022] [Indexed: 12/20/2022]
Abstract
An appropriate sensory experience during the early developmental period is important for brain maturation. Dark rearing during the visual critical period delays the maturation of neuronal circuits in the visual cortex. Although the formation and structural plasticity of the myelin sheaths on retinal ganglion cell axons modulate the visual function, the effects of dark rearing during the visual critical period on the structure of the retinal ganglion cell axons and their myelin sheaths are still unclear. To address this question, mice were reared in a dark box during the visual critical period and then normally reared to adulthood. We found that myelin sheaths on the retinal ganglion cell axons of dark-reared mice were thicker than those of normally reared mice in both the optic chiasm and optic nerve. Furthermore, whole-mount immunostaining with fluorescent axonal labeling and tissue clearing revealed that the myelin internodal length in dark-reared mice was shorter than that in normally reared mice in both the optic chiasm and optic nerve. These findings demonstrate that dark rearing during the visual critical period affects the morphology of myelin sheaths, shortens and thickens myelin sheaths in the visual pathway, despite the mice being reared in normal light/dark conditions after the dark rearing.
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Affiliation(s)
- Yasuyuki Osanai
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan. .,Australian Regenerative Medicine Institute, Monash University, 15 Innovation Walk, Clayton, VIC, 3800, Australia.
| | - Batpurev Battulga
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Reiji Yamazaki
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Tom Kouki
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Megumi Yatabe
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Hiroaki Mizukami
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Kenta Kobayashi
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Yoshiaki Shinohara
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Yumiko Yoshimura
- SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan.,Division of Visual Information Processing, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan
| | - Nobuhiko Ohno
- Division of Histology and Cell Biology, Department of Anatomy, School of Medicine, Jichi Medical University, Shimotsuke, Japan. .,Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, Japan.
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26
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Malara M, Lutz AK, Incearap B, Bauer HF, Cursano S, Volbracht K, Lerner JJ, Pandey R, Delling JP, Ioannidis V, Arévalo AP, von Bernhardi JE, Schön M, Bockmann J, Dimou L, Boeckers TM. SHANK3 deficiency leads to myelin defects in the central and peripheral nervous system. Cell Mol Life Sci 2022; 79:371. [PMID: 35726031 PMCID: PMC9209365 DOI: 10.1007/s00018-022-04400-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/11/2022] [Accepted: 05/25/2022] [Indexed: 01/04/2023]
Abstract
Mutations or deletions of the SHANK3 gene are causative for Phelan–McDermid syndrome (PMDS), a syndromic form of autism spectrum disorders (ASDs). We analyzed Shank3Δ11(−/−) mice and organoids from PMDS individuals to study effects on myelin. SHANK3 was found to be expressed in oligodendrocytes and Schwann cells, and MRI analysis of Shank3Δ11(−/−) mice revealed a reduced volume of the corpus callosum as seen in PMDS patients. Myelin proteins including myelin basic protein showed significant temporal and regional differences with lower levels in the CNS but increased amounts in the PNS of Shank3Δ11(−/−) animals. Node, as well as paranode, lengths were increased and ultrastructural analysis revealed region-specific alterations of the myelin sheaths. In PMDS hiPSC-derived cerebral organoids we observed an altered number and delayed maturation of myelinating cells. These findings provide evidence that, in addition to a synaptic deregulation, impairment of myelin might profoundly contribute to the clinical manifestation of SHANK3 deficiency.
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Affiliation(s)
- Mariagiovanna Malara
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
- International Graduate School in Molecular Medicine, IGradU, 89081, Ulm, Germany
| | - Anne-Kathrin Lutz
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Berra Incearap
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
- International Graduate School in Molecular Medicine, IGradU, 89081, Ulm, Germany
| | - Helen Friedericke Bauer
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
- International Graduate School in Molecular Medicine, IGradU, 89081, Ulm, Germany
| | - Silvia Cursano
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Katrin Volbracht
- Molecular and Translational Neuroscience, Department of Neurology, Ulm University, 89081, Ulm, Germany
| | - Joanna Janina Lerner
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
- International Graduate School in Molecular Medicine, IGradU, 89081, Ulm, Germany
| | - Rakshita Pandey
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Jan Philipp Delling
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Valentin Ioannidis
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Andrea Pérez Arévalo
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | | | - Michael Schön
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Jürgen Bockmann
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany
| | - Leda Dimou
- Molecular and Translational Neuroscience, Department of Neurology, Ulm University, 89081, Ulm, Germany
| | - Tobias M Boeckers
- Institute for Anatomy and Cell Biology, Ulm University, Albert-Einstein Allee 11, 89081, Ulm, Germany.
- DZNE, Ulm Site, 89081, Ulm, Germany.
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27
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Lazari A, Salvan P, Cottaar M, Papp D, Rushworth MFS, Johansen-Berg H. Hebbian activity-dependent plasticity in white matter. Cell Rep 2022; 39:110951. [PMID: 35705046 PMCID: PMC9376741 DOI: 10.1016/j.celrep.2022.110951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/07/2022] [Accepted: 05/23/2022] [Indexed: 11/28/2022] Open
Abstract
Synaptic plasticity is required for learning and follows Hebb's rule, the computational principle underpinning associative learning. In recent years, a complementary type of brain plasticity has been identified in myelinated axons, which make up the majority of brain's white matter. Like synaptic plasticity, myelin plasticity is required for learning, but it is unclear whether it is Hebbian or whether it follows different rules. Here, we provide evidence that white matter plasticity operates following Hebb's rule in humans. Across two experiments, we find that co-stimulating cortical areas to induce Hebbian plasticity leads to relative increases in cortical excitability and associated increases in a myelin marker within the stimulated fiber bundle. We conclude that Hebbian plasticity extends beyond synaptic changes and can be observed in human white matter fibers.
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Affiliation(s)
- Alberto Lazari
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX2 6GG, UK.
| | - Piergiorgio Salvan
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX2 6GG, UK
| | - Michiel Cottaar
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX2 6GG, UK
| | - Daniel Papp
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX2 6GG, UK
| | - Matthew F S Rushworth
- Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, UK
| | - Heidi Johansen-Berg
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX2 6GG, UK
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28
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Protocadherin 15 suppresses oligodendrocyte progenitor cell proliferation and promotes motility through distinct signalling pathways. Commun Biol 2022; 5:511. [PMID: 35637313 PMCID: PMC9151716 DOI: 10.1038/s42003-022-03470-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 05/10/2022] [Indexed: 12/15/2022] Open
Abstract
Oligodendrocyte progenitor cells (OPCs) express protocadherin 15 (Pcdh15), a member of the cadherin superfamily of transmembrane proteins. Little is known about the function of Pcdh15 in the central nervous system (CNS), however, Pcdh15 expression can predict glioma aggression and promote the separation of embryonic human OPCs immediately following a cell division. Herein, we show that Pcdh15 knockdown significantly increases extracellular signal-related kinase (ERK) phosphorylation and activation to enhance OPC proliferation in vitro. Furthermore, Pcdh15 knockdown elevates Cdc42-Arp2/3 signalling and impairs actin kinetics, reducing the frequency of lamellipodial extrusion and slowing filopodial withdrawal. Pcdh15 knockdown also reduces the number of processes supported by each OPC and new process generation. Our data indicate that Pcdh15 is a critical regulator of OPC proliferation and process motility, behaviours that characterise the function of these cells in the healthy CNS, and provide mechanistic insight into the role that Pcdh15 might play in glioma progression. Protocadherin 15 promotes lamellipodial and filopodial dynamics in oligodendrocyte progenitor cells by regulating Cdc42-Arp2/3 activity, but also suppresses ERK1/2 phosphorylation to reduce proliferation.
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Shimba K, Asahina T, Sakai K, Kotani K, Jimbo Y. Recording Saltatory Conduction Along Sensory Axons Using a High-Density Microelectrode Array. Front Neurosci 2022; 16:854637. [PMID: 35509449 PMCID: PMC9058065 DOI: 10.3389/fnins.2022.854637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022] Open
Abstract
Myelinated fibers are specialized neurological structures used for conducting action potentials quickly and reliably, thus assisting neural functions. Although demyelination leads to serious functional impairments, little is known the relationship between myelin structural change and increase in conduction velocity during myelination and demyelination processes. There are no appropriate methods for the long-term evaluation of spatial characteristics of saltatory conduction along myelinated axons. Herein, we aimed to detect saltatory conduction from the peripheral nervous system neurons using a high-density microelectrode array. Rat sensory neurons and intrinsic Schwann cells were cultured. Immunofluorescence and ultrastructure examination showed that the myelinating Schwann cells appeared at 1 month, and compact myelin was formed by 10 weeks in vitro. Activity of rat sensory neurons was evoked with optogenetic stimulation, and axon conduction was detected with high-density microelectrode arrays. Some conductions included high-speed segments with low signal amplitude. The same segment could be detected with electrical recording and immunofluorescent imaging for a myelin-related protein. The spatiotemporal analysis showed that some segments show a velocity of more than 2 m/s and that ends of the segments show a higher electrical sink, suggesting that saltatory conduction occurred in myelinated axons. Moreover, mathematical modeling supported that the recorded signal was in the appropriate range for axon and electrode sizes. Overall, our method could be a feasible tool for evaluating spatial characteristics of axon conduction including saltatory conduction, which is applicable for studying demyelination and remyelination.
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Affiliation(s)
- Kenta Shimba
- Department of Precision Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
- *Correspondence: Kenta Shimba, , orcid.org/0000-0003-1156-260X
| | - Takahiro Asahina
- Department of Precision Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
- Japan Society for Promotion of Science, Tokyo, Japan
| | - Koji Sakai
- Department of Precision Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Kiyoshi Kotani
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Yasuhiko Jimbo
- Department of Precision Engineering, School of Engineering, The University of Tokyo, Tokyo, Japan
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30
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Moretti J, Rodger J. A little goes a long way: Neurobiological effects of low intensity rTMS and implications for mechanisms of rTMS. CURRENT RESEARCH IN NEUROBIOLOGY 2022; 3:100033. [PMID: 36685761 PMCID: PMC9846462 DOI: 10.1016/j.crneur.2022.100033] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 01/26/2022] [Accepted: 02/15/2022] [Indexed: 01/25/2023] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is a widespread technique in neuroscience and medicine, however its mechanisms are not well known. In this review, we consider intensity as a key therapeutic parameter of rTMS, and review the studies that have examined the biological effects of rTMS using magnetic fields that are orders of magnitude lower that those currently used in the clinic. We discuss how extensive characterisation of "low intensity" rTMS has set the stage for translation of new rTMS parameters from a mechanistic evidence base, with potential for innovative and effective therapeutic applications. Low-intensity rTMS demonstrates neurobiological effects across healthy and disease models, which include depression, injury and regeneration, abnormal circuit organisation, tinnitus etc. Various short and long-term changes to metabolism, neurotransmitter release, functional connectivity, genetic changes, cell survival and behaviour have been investigated and we summarise these key changes and the possible mechanisms behind them. Mechanisms at genetic, molecular, cellular and system levels have been identified with evidence that low-intensity rTMS and potentially rTMS in general acts through several key pathways to induce changes in the brain with modulation of internal calcium signalling identified as a major mechanism. We discuss the role that preclinical models can play to inform current clinical research as well as uncover new pathways for investigation.
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Affiliation(s)
- Jessica Moretti
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia,Perron Institute for Neurological and Translational Science, Perth, WA, Australia
| | - Jennifer Rodger
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia,Perron Institute for Neurological and Translational Science, Perth, WA, Australia,Corresponding author. School of Biological Sciences M317, The University of Western Australia, 35 Stirling Highway, Crawley WA, 6009, Australia.
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31
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The oligodendrocyte-enriched orphan G protein-coupled receptor Gpr62 is dispensable for central nervous system myelination. Neural Dev 2021; 16:6. [PMID: 34844642 PMCID: PMC8630896 DOI: 10.1186/s13064-021-00156-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Myelination is a highly regulated process in the vertebrate central nervous system (CNS) whereby oligodendrocytes wrap axons with multiple layers of insulating myelin in order to allow rapid electrical conduction. Establishing the proper pattern of myelin in neural circuits requires communicative axo-glial interactions, however, the molecular interactions that occur between oligodendrocytes and axons during developmental myelination and myelin maintenance remain to be fully elucidated. Our previous work identified G protein-coupled receptor 62 (Gpr62), an uncharacterized orphan g-protein coupled receptor, as being selectively expressed by mature oligodendrocytes within the CNS, suggesting a potential role in myelination or axoglial interactions. However, no studies to date have assessed the functional requirement for Gpr62 in oligodendrocyte development or CNS myelination. METHODS To address this, we generated a knockout mouse strain lacking the Gpr62 gene. We assessed CNS myelination during both postnatal development and adulthood using immunohistochemistry, electron microscopy and western blot. In addition, we utilized AAV-mediated expression of a tagged Gpr62 in oligodendrocytes to determine the subcellular localization of the protein in vivo. RESULTS We find that virally expressed Gpr62 protein is selectively expressed on the adaxonal myelin layer, suggestive of a potential role for Gpr62 in axo-myelinic signaling. Nevertheless, Gpr62 knockout mice display normal oligodendrocyte numbers and apparently normal myelination within the CNS during both postnatal development and adulthood. CONCLUSIONS We conclude that in spite of being well-placed to mediate neuronal-oligodendrocyte communications, Gpr62 is overall dispensable for CNS myelination.
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Experience-dependent myelination following stress is mediated by the neuropeptide dynorphin. Neuron 2021; 109:3619-3632.e5. [PMID: 34536353 DOI: 10.1016/j.neuron.2021.08.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/14/2021] [Accepted: 08/13/2021] [Indexed: 11/22/2022]
Abstract
Emerging evidence implicates experience-dependent myelination in learning and memory. However, the specific signals underlying this process remain unresolved. We demonstrate that the neuropeptide dynorphin, which is released from neurons upon high levels of activity, promotes experience-dependent myelination. Following forced swim stress, an experience that induces striatal dynorphin release, we observe increased striatal oligodendrocyte precursor cell (OPC) differentiation and myelination, which is abolished by deleting dynorphin or blocking its endogenous receptor, kappa opioid receptor (KOR). We find that dynorphin also promotes developmental OPC differentiation and myelination and demonstrate that this effect requires KOR expression specifically in OPCs. We characterize dynorphin-expressing neurons and use genetic sparse labeling to trace their axonal projections. Surprisingly, we find that they are unmyelinated normally and following forced swim stress. We propose a new model whereby experience-dependent and developmental myelination is mediated by unmyelinated, neuropeptide-expressing neurons that promote OPC differentiation for the myelination of neighboring axons.
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33
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Periods of synchronized myelin changes shape brain function and plasticity. Nat Neurosci 2021; 24:1508-1521. [PMID: 34711959 DOI: 10.1038/s41593-021-00917-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 07/30/2021] [Indexed: 12/11/2022]
Abstract
Myelin, a lipid membrane that wraps axons, enabling fast neurotransmission and metabolic support to axons, is conventionally thought of as a static structure that is set early in development. However, recent evidence indicates that in the central nervous system (CNS), myelination is a protracted and plastic process, ongoing throughout adulthood. Importantly, myelin is emerging as a potential modulator of neuronal networks, and evidence from human studies has highlighted myelin as a major player in shaping human behavior and learning. Here we review how myelin changes throughout life and with learning. We discuss potential mechanisms of myelination at different life stages, explore whether myelin plasticity provides the regenerative potential of the CNS white matter, and question whether changes in myelin may underlie neurological disorders.
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34
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Tang AD, Bennett W, Bindoff AD, Bolland S, Collins J, Langley RC, Garry MI, Summers JJ, Hinder MR, Rodger J, Canty AJ. Subthreshold repetitive transcranial magnetic stimulation drives structural synaptic plasticity in the young and aged motor cortex. Brain Stimul 2021; 14:1498-1507. [PMID: 34653682 DOI: 10.1016/j.brs.2021.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 09/27/2021] [Accepted: 10/11/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive tool commonly used to drive neural plasticity in the young adult and aged brain. Recent data from mouse models have shown that even at subthreshold intensities (0.12 T), rTMS can drive neuronal and glial plasticity in the motor cortex. However, the physiological mechanisms underlying subthreshold rTMS induced plasticity and whether these are altered with normal ageing are unclear. OBJECTIVE To assess the effect of subthreshold rTMS, using the intermittent theta burst stimulation (iTBS) protocol on structural synaptic plasticity in the mouse motor cortex of young and aged mice. METHODS Longitudinal in vivo 2-photon microscopy was used to measure changes to the structural plasticity of pyramidal neuron dendritic spines in the motor cortex following a single train of subthreshold rTMS (in young adult and aged animals) or the same rTMS train administered on 4 consecutive days (in young adult animals only). Data were analysed with Bayesian hierarchical generalized linear regression models and interpreted with the aid of Bayes Factors (BF). RESULTS We found strong evidence (BF > 10) that subthreshold rTMS altered the rate of dendritic spine losses and gains, dependent on the number of stimulation sessions and that a single session of subthreshold rTMS was effective in driving structural synaptic plasticity in both young adult and aged mice. CONCLUSION These findings provide further evidence that rTMS drives synaptic plasticity in the brain and uncovers structural synaptic plasticity as a key mechanism of subthreshold rTMS induced plasticity.
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Affiliation(s)
- Alexander D Tang
- Experimental and Regenerative Neurosciences, School of Biological Sciences, University of Western Australia, 35 Stirling Highway (M317), Crawley, 6009, WA, Australia; Perron Institute for Neurological and Translational Sciences, 8 Verdun Street, Nedlands, 6008, WA, Australia.
| | - William Bennett
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Private Bag 143, Hobart, 7001, TAS, Australia
| | - Aidan D Bindoff
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Private Bag 143, Hobart, 7001, TAS, Australia
| | - Samuel Bolland
- Experimental and Regenerative Neurosciences, School of Biological Sciences, University of Western Australia, 35 Stirling Highway (M317), Crawley, 6009, WA, Australia; Perron Institute for Neurological and Translational Sciences, 8 Verdun Street, Nedlands, 6008, WA, Australia
| | - Jessica Collins
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Private Bag 143, Hobart, 7001, TAS, Australia
| | - Ross C Langley
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Private Bag 143, Hobart, 7001, TAS, Australia
| | - Michael I Garry
- School of Psychological Sciences, College of Health and Medicine, University of Tasmania, Hobart, Australia. Private Bag 30, Hobart, 7001, TAS, Australia
| | - Jeffery J Summers
- School of Psychological Sciences, College of Health and Medicine, University of Tasmania, Hobart, Australia. Private Bag 30, Hobart, 7001, TAS, Australia; Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, L3 3AF, Liverpool, United Kingdom
| | - Mark R Hinder
- School of Psychological Sciences, College of Health and Medicine, University of Tasmania, Hobart, Australia. Private Bag 30, Hobart, 7001, TAS, Australia
| | - Jennifer Rodger
- Experimental and Regenerative Neurosciences, School of Biological Sciences, University of Western Australia, 35 Stirling Highway (M317), Crawley, 6009, WA, Australia; Perron Institute for Neurological and Translational Sciences, 8 Verdun Street, Nedlands, 6008, WA, Australia
| | - Alison J Canty
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Private Bag 143, Hobart, 7001, TAS, Australia
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35
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Seewoo BJ, Feindel KW, Won Y, Joos AC, Figliomeni A, Hennessy LA, Rodger J. White Matter Changes Following Chronic Restraint Stress and Neuromodulation: A Diffusion Magnetic Resonance Imaging Study in Young Male Rats. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2021; 2:153-166. [PMID: 36325163 PMCID: PMC9616380 DOI: 10.1016/j.bpsgos.2021.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/27/2021] [Accepted: 08/16/2021] [Indexed: 11/23/2022] Open
Abstract
Background Repetitive transcranial magnetic stimulation (rTMS), a noninvasive neuromodulation technique, is an effective treatment for depression. However, few studies have used diffusion magnetic resonance imaging to investigate the longitudinal effects of rTMS on the abnormal brain white matter (WM) described in depression. Methods In this study, we acquired diffusion magnetic resonance imaging from young adult male Sprague Dawley rats to investigate 1) the longitudinal effects of 10- and 1-Hz low-intensity rTMS (LI-rTMS) in healthy animals; 2) the effect of chronic restraint stress (CRS), an animal model of depression; and 3) the effect of 10 Hz LI-rTMS in CRS animals. Diffusion magnetic resonance imaging data were analyzed using tract-based spatial statistics and fixel-based analysis. Results Similar changes in diffusion and kurtosis fractional anisotropy were induced by 10- and 1-Hz stimulation in healthy animals, although changes induced by 10-Hz stimulation were detected earlier than those following 1-Hz stimulation. Additionally, 10-Hz stimulation increased axial and mean kurtosis within the external capsule, suggesting that the two protocols may act via different underlying mechanisms. Brain maturation–related changes in WM, such as increased corpus callosum, fimbria, and external and internal capsule fiber cross-section, were compromised in CRS animals compared with healthy control animals and were rescued by 10-Hz LI-rTMS. Immunohistochemistry revealed increased myelination within the corpus callosum in LI-rTMS–treated CRS animals compared with those that received sham or no stimulation. Conclusions Overall, decreased WM connectivity and integrity in the CRS model corroborate findings in patients experiencing depression with high anxiety, and the observed LI-rTMS–induced effects on WM structure suggest that LI-rTMS might rescue abnormal WM by increasing myelination.
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36
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Pan X, Zhou Y, Hotulainen P, Meunier FA, Wang T. The axonal radial contractility: Structural basis underlying a new form of neural plasticity. Bioessays 2021; 43:e2100033. [PMID: 34145916 DOI: 10.1002/bies.202100033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 12/25/2022]
Abstract
Axons are the longest cellular structure reaching over a meter in the case of human motor axons. They have a relatively small diameter and contain several cytoskeletal elements that mediate both material and information exchange within neurons. Recently, a novel type of axonal plasticity, termed axonal radial contractility, has been unveiled. It is represented by dynamic and transient diameter changes of the axon shaft to accommodate the passages of large organelles. Mechanisms underpinning this plasticity are not fully understood. Here, we first summarised recent evidence of the functional relevance for axon radial contractility, then discussed the underlying structural basis, reviewing nanoscopic evidence of the subtle changes. Two models are proposed to explain how actomyosin rings are organised. Possible roles of non-muscle myosin II (NM-II) in axon degeneration are discussed. Finally, we discuss the concept of periodic functional nanodomains, which could sense extracellular cues and coordinate the axonal responses. Also see the video abstract here: https://youtu.be/ojCnrJ8RCRc.
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Affiliation(s)
- Xiaorong Pan
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Yimin Zhou
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Tong Wang
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
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37
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Moyon S, Frawley R, Marechal D, Huang D, Marshall-Phelps KLH, Kegel L, Bøstrand SMK, Sadowski B, Jiang YH, Lyons DA, Möbius W, Casaccia P. TET1-mediated DNA hydroxymethylation regulates adult remyelination in mice. Nat Commun 2021; 12:3359. [PMID: 34099715 PMCID: PMC8185117 DOI: 10.1038/s41467-021-23735-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/10/2021] [Indexed: 12/17/2022] Open
Abstract
The mechanisms regulating myelin repair in the adult central nervous system (CNS) are unclear. Here, we identify DNA hydroxymethylation, catalyzed by the Ten-Eleven-Translocation (TET) enzyme TET1, as necessary for myelin repair in young adults and defective in old mice. Constitutive and inducible oligodendrocyte lineage-specific ablation of Tet1 (but not of Tet2), recapitulate this age-related decline in repair of demyelinated lesions. DNA hydroxymethylation and transcriptomic analyses identify TET1-target in adult oligodendrocytes, as genes regulating neuro-glial communication, including the solute carrier (Slc) gene family. Among them, we show that the expression levels of the Na+/K+/Cl- transporter, SLC12A2, are higher in Tet1 overexpressing cells and lower in old or Tet1 knockout. Both aged mice and Tet1 mutants also present inefficient myelin repair and axo-myelinic swellings. Zebrafish mutants for slc12a2b also display swellings of CNS myelinated axons. Our findings suggest that TET1 is required for adult myelin repair and regulation of the axon-myelin interface.
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Affiliation(s)
- Sarah Moyon
- Neuroscience Initiative Advanced Science Research Center, New York, NY, USA.
| | - Rebecca Frawley
- Neuroscience Initiative Advanced Science Research Center, New York, NY, USA
| | - Damien Marechal
- Neuroscience Initiative Advanced Science Research Center, New York, NY, USA
| | - Dennis Huang
- Neuroscience Initiative Advanced Science Research Center, New York, NY, USA
| | | | - Linde Kegel
- Centre for Discovery Brain Sciences, Edinburgh, UK
| | | | - Boguslawa Sadowski
- Department of Neurogenetics, Göttingen, Germany
- Electron Microscopy Core Unit, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Yong-Hui Jiang
- Department of Neurobiology and Pediatrics, Duke University School of Medicine, Durham, NC, USA
| | | | - Wiebke Möbius
- Department of Neurogenetics, Göttingen, Germany
- Electron Microscopy Core Unit, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Patrizia Casaccia
- Neuroscience Initiative Advanced Science Research Center, New York, NY, USA.
- Program of Biology and Biochemistry, The Graduate Center of The City University of New York, New York, NY, USA.
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Fletcher JL, Makowiecki K, Cullen CL, Young KM. Oligodendrogenesis and myelination regulate cortical development, plasticity and circuit function. Semin Cell Dev Biol 2021; 118:14-23. [PMID: 33863642 DOI: 10.1016/j.semcdb.2021.03.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/23/2021] [Accepted: 03/25/2021] [Indexed: 12/17/2022]
Abstract
During cortical development and throughout adulthood, oligodendrocytes add myelin internodes to glutamatergic projection neurons and GABAergic inhibitory neurons. In addition to directing node of Ranvier formation, to enable saltatory conduction and influence action potential transit time, oligodendrocytes support axon health by communicating with axons via the periaxonal space and providing metabolic support that is particularly critical for healthy ageing. In this review we outline the timing of oligodendrogenesis in the developing mouse and human cortex and describe the important role that oligodendrocytes play in sustaining and modulating neuronal function. We also provide insight into the known and speculative impact that myelination has on cortical axons and their associated circuits during the developmental critical periods and throughout life, particularly highlighting their life-long role in learning and remembering.
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Affiliation(s)
- Jessica L Fletcher
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Kalina Makowiecki
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Carlie L Cullen
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Kaylene M Young
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.
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39
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Mazuir E, Fricker D, Sol-Foulon N. Neuron-Oligodendrocyte Communication in Myelination of Cortical GABAergic Cells. Life (Basel) 2021; 11:216. [PMID: 33803153 PMCID: PMC7999565 DOI: 10.3390/life11030216] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/01/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022] Open
Abstract
Axonal myelination by oligodendrocytes increases the speed and reliability of action potential propagation, and so plays a pivotal role in cortical information processing. The extent and profile of myelination vary between different cortical layers and groups of neurons. Two subtypes of cortical GABAergic neurons are myelinated: fast-spiking parvalbumin-expressing cells and somatostatin-containing cells. The expression of pre-nodes on the axon of these inhibitory cells before myelination illuminates communication between oligodendrocytes and neurons. We explore the consequences of myelination for action potential propagation, for patterns of neuronal connectivity and for the expression of behavioral plasticity.
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Affiliation(s)
- Elisa Mazuir
- Inserm, CNRS, Paris Brain Institute, ICM, Sorbonne University, Pitié-Salpêtrière Hospital, F-75013 Paris, France
| | - Desdemona Fricker
- CNRS UMR 8002, Integrative Neuroscience and Cognition Center, Université de Paris, F-75006 Paris, France
| | - Nathalie Sol-Foulon
- Inserm, CNRS, Paris Brain Institute, ICM, Sorbonne University, Pitié-Salpêtrière Hospital, F-75013 Paris, France
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40
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Duncan GJ, Simkins TJ, Emery B. Neuron-Oligodendrocyte Interactions in the Structure and Integrity of Axons. Front Cell Dev Biol 2021; 9:653101. [PMID: 33763430 PMCID: PMC7982542 DOI: 10.3389/fcell.2021.653101] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022] Open
Abstract
The myelination of axons by oligodendrocytes is a highly complex cell-to-cell interaction. Oligodendrocytes and axons have a reciprocal signaling relationship in which oligodendrocytes receive cues from axons that direct their myelination, and oligodendrocytes subsequently shape axonal structure and conduction. Oligodendrocytes are necessary for the maturation of excitatory domains on the axon including nodes of Ranvier, help buffer potassium, and support neuronal energy metabolism. Disruption of the oligodendrocyte-axon unit in traumatic injuries, Alzheimer's disease and demyelinating diseases such as multiple sclerosis results in axonal dysfunction and can culminate in neurodegeneration. In this review, we discuss the mechanisms by which demyelination and loss of oligodendrocytes compromise axons. We highlight the intra-axonal cascades initiated by demyelination that can result in irreversible axonal damage. Both the restoration of oligodendrocyte myelination or neuroprotective therapies targeting these intra-axonal cascades are likely to have therapeutic potential in disorders in which oligodendrocyte support of axons is disrupted.
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Affiliation(s)
- Greg J Duncan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
| | - Tyrell J Simkins
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States.,Vollum Institute, Oregon Health & Science University, Portland, OR, United States.,Department of Neurology, VA Portland Health Care System, Portland, OR, United States
| | - Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
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