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Matcham AC, Toma K, Tsai NY, Sze CJ, Lin PY, Stewart IF, Duan X. Cadherin-13 Maintains Retinotectal Synapses via Transneuronal Interactions. J Neurosci 2024; 44:e1310232023. [PMID: 38123991 PMCID: PMC10860569 DOI: 10.1523/jneurosci.1310-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
Maintaining precise synaptic contacts between neuronal partners is critical to ensure the proper functioning of the mammalian central nervous system (CNS). Diverse cell recognition molecules, such as classic cadherins (Cdhs), are part of the molecular machinery mediating synaptic choices during development and synaptic maintenance. Yet, the principles governing neuron-neuron wiring across diverse CNS neuron types remain largely unknown. The retinotectal synapses, connections from the retinal ganglion cells (RGCs) to the superior collicular (SC) neurons, offer an ideal experimental system to reveal molecular logic underlying synaptic choices and formation. This is due to the retina's unidirectional and laminar-restricted projections to the SC and the large databases of presynaptic RGC subtypes and postsynaptic SC neuronal types. Here, we focused on determining the role of Type II Cdhs in wiring the retinotectal synapses. We surveyed Cdhs expression patterns at neuronal resolution and revealed that Cdh13 is enriched in the wide-field neurons in the superficial SC (sSC). In either the Cdh13 null mutant or selective adult deletion within the wide-field neurons, there is a significant reduction of spine densities in the distal dendrites of these neurons in both sexes. Additionally, Cdh13 removal from presynaptic RGCs reduced dendritic spines in the postsynaptic wide-field neurons. Cdh13-expressing RGCs use differential mechanisms than αRGCs and On-Off Direction-Selective Ganglion Cells (ooDSGCs) to form specific retinotectal synapses. The results revealed a selective transneuronal interaction mediated by Cdh13 to maintain proper retinotectal synapses in vivo.
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Affiliation(s)
- Angela C Matcham
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Kenichi Toma
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Nicole Y Tsai
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Christina J Sze
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Pin-Yeh Lin
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Ilaria F Stewart
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
| | - Xin Duan
- Neuroscience Graduate Program, Department of Ophthalmology, Kavli Institute for Fundamental Neuroscience, University of California SanFrancisco, San Francisco 94143-2811, California
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2
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Teh KL, Sibille J, Gehr C, Kremkow J. Retinal waves align the concentric orientation map in mouse superior colliculus to the center of vision. SCIENCE ADVANCES 2023; 9:eadf4240. [PMID: 37172095 PMCID: PMC10181181 DOI: 10.1126/sciadv.adf4240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Neurons in the mouse superior colliculus (SC) are arranged in a concentric orientation map, which is aligned to the center of vision and the optic flow experienced by the mouse. The origin of this map remains unclear. Here, we propose that spontaneous retinal waves during development provide a scaffold to establish the concentric orientation map within the SC and its alignment to the optic flow. We test this hypothesis by modeling the orientation-tuned SC neurons that receive ON/OFF retinal inputs. Our model suggests that the propagation direction bias of stage III retinal waves, together with OFF-delayed responses, shapes the spatial organization of the orientation map. The OFF delay establishes orientation-tuned neurons by segregating their ON/OFF receptive subfields, the wave-like activities form the concentric pattern, and the direction biases align the map to the center of vision. Together, retinal waves may play an instructive role in establishing functional properties of single SC neurons and their spatial organization within maps.
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Affiliation(s)
- Kai Lun Teh
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience Berlin, Philippstraße 13, Berlin 10115, Germany
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin 10115, Germany
- Einstein Center for Neurosciences Berlin, Charitéplatz 1, Berlin, Germany
| | - Jérémie Sibille
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience Berlin, Philippstraße 13, Berlin 10115, Germany
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin 10115, Germany
- Einstein Center for Neurosciences Berlin, Charitéplatz 1, Berlin, Germany
| | - Carolin Gehr
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience Berlin, Philippstraße 13, Berlin 10115, Germany
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin 10115, Germany
- Einstein Center for Neurosciences Berlin, Charitéplatz 1, Berlin, Germany
| | - Jens Kremkow
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience Berlin, Philippstraße 13, Berlin 10115, Germany
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin 10115, Germany
- Einstein Center for Neurosciences Berlin, Charitéplatz 1, Berlin, Germany
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3
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Tsai NY, Wang F, Toma K, Yin C, Takatoh J, Pai EL, Wu K, Matcham AC, Yin L, Dang EJ, Marciano DK, Rubenstein JL, Wang F, Ullian EM, Duan X. Trans-Seq maps a selective mammalian retinotectal synapse instructed by Nephronectin. Nat Neurosci 2022; 25:659-674. [PMID: 35524141 PMCID: PMC9172271 DOI: 10.1038/s41593-022-01068-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 03/30/2022] [Indexed: 12/21/2022]
Abstract
The mouse visual system serves as an accessible model to understand mammalian circuit wiring. Despite rich knowledge in retinal circuits, the long-range connectivity map from distinct retinal ganglion cell (RGC) types to diverse brain neuron types remains unknown. In this study, we developed an integrated approach, called Trans-Seq, to map RGCs to superior collicular (SC) circuits. Trans-Seq combines a fluorescent anterograde trans-synaptic tracer, consisting of codon-optimized wheat germ agglutinin fused to mCherry, with single-cell RNA sequencing. We used Trans-Seq to classify SC neuron types innervated by genetically defined RGC types and predicted a neuronal pair from αRGCs to Nephronectin-positive wide-field neurons (NPWFs). We validated this connection using genetic labeling, electrophysiology and retrograde tracing. We then used transcriptomic data from Trans-Seq to identify Nephronectin as a determinant for selective synaptic choice from αRGC to NPWFs via binding to Integrin α8β1. The Trans-Seq approach can be broadly applied for post-synaptic circuit discovery from genetically defined pre-synaptic neurons.
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Affiliation(s)
- Nicole Y Tsai
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
- Medical Scientist Training Program and Biomedical Science Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Fei Wang
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Kenichi Toma
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Chen Yin
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Jun Takatoh
- McGovern Institute for Brain Research, MIT Brain and Cognitive Sciences, Cambridge, MA, USA
| | - Emily L Pai
- Neuroscience Graduate Program, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA
| | - Kongyan Wu
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Angela C Matcham
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
- Neuroscience Graduate Program, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Luping Yin
- McGovern Institute for Brain Research, MIT Brain and Cognitive Sciences, Cambridge, MA, USA
| | - Eric J Dang
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Denise K Marciano
- Departments of Cell Biology and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - John L Rubenstein
- Neuroscience Graduate Program, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA
| | - Fan Wang
- McGovern Institute for Brain Research, MIT Brain and Cognitive Sciences, Cambridge, MA, USA
| | - Erik M Ullian
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Xin Duan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA.
- Department of Physiology, University of California, San Francisco, San Francisco, CA, USA.
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, USA.
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4
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Chowdhury D, Watters K, Biederer T. Synaptic recognition molecules in development and disease. Curr Top Dev Biol 2021; 142:319-370. [PMID: 33706921 DOI: 10.1016/bs.ctdb.2020.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Synaptic connectivity patterns underlie brain functions. How recognition molecules control where and when neurons form synapses with each other, therefore, is a fundamental question of cellular neuroscience. This chapter delineates adhesion and signaling complexes as well as secreted factors that contribute to synaptic partner recognition in the vertebrate brain. The sections follow a developmental perspective and discuss how recognition molecules (1) guide initial synaptic wiring, (2) provide for the rejection of incorrect partner choices, (3) contribute to synapse specification, and (4) support the removal of inappropriate synapses once formed. These processes involve a rich repertoire of molecular players and key protein families are described, notably the Cadherin and immunoglobulin superfamilies, Semaphorins/Plexins, Leucine-rich repeat containing proteins, and Neurexins and their binding partners. Molecular themes that diversify these recognition systems are defined and highlighted throughout the text, including the neuron-type specific expression and combinatorial action of recognition factors, alternative splicing, and post-translational modifications. Methodological innovations advancing the field such as proteomic approaches and single cell expression studies are additionally described. Further, the chapter highlights the importance of choosing an appropriate brain region to analyze synaptic recognition factors and the advantages offered by laminated structures like the hippocampus or retina. In a concluding section, the profound disease relevance of aberrant synaptic recognition for neurodevelopmental and psychiatric disorders is discussed. Based on the current progress, an outlook is presented on research goals that can further advance insights into how recognition molecules provide for the astounding precision and diversity of synaptic connections.
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Affiliation(s)
| | - Katherine Watters
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States; Neuroscience Graduate Program, Tufts University School of Medicine, Boston, MA, United States
| | - Thomas Biederer
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States.
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5
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Graham HK, Duan X. Molecular mechanisms regulating synaptic specificity and retinal circuit formation. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 10:e379. [PMID: 32267095 DOI: 10.1002/wdev.379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 03/13/2020] [Accepted: 03/19/2020] [Indexed: 12/28/2022]
Abstract
The central nervous system (CNS) is composed of precisely assembled circuits which support a variety of physiological functions and behaviors. These circuits include multiple subtypes of neurons with unique morphologies, electrical properties, and molecular identities. How these component parts are precisely wired-up has been a topic of great interest to the field of developmental neurobiology and has implications for our understanding of the etiology of many neurological disorders and mental illnesses. To date, many molecules involved in synaptic choice and specificity have been identified, including members of several families of cell-adhesion molecules (CAMs), which are cell-surface molecules that mediate cell-cell contacts and subsequent intracellular signaling. One favored hypothesis is that unique expression patterns of CAMs define specific neuronal subtype populations and determine compatible pre- and postsynaptic neuronal partners based on the expression of these unique CAMs. The mouse retina has served as a beautiful model for investigations into mammalian CAM interactions due to its well-defined neuronal subtypes and distinct circuits. Moreover, the retina is readily amenable to visualization of circuit organization and electrophysiological measurement of circuit function. The advent of recent genetic, genomic, and imaging technologies has opened the field up to large-scale, unbiased approaches for identification of new molecular determinants of synaptic specificity. Thus, building on the foundation of work reviewed here, we can expect rapid expansion of the field, harnessing the mouse retina as a model to understand the molecular basis for synaptic specificity and functional circuit assembly. This article is categorized under: Nervous System Development > Vertebrates: General Principles Nervous System Development > Vertebrates: Regional Development.
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Affiliation(s)
- Hannah K Graham
- Department of Ophthalmology, University of California San Francisco, San Francisco, California, USA.,Neuroscience Graduate Program, Weill Institute for Neurosciences, University of California San Francisco, San Francisco, California, USA
| | - Xin Duan
- Department of Ophthalmology, University of California San Francisco, San Francisco, California, USA.,Neuroscience Graduate Program, Weill Institute for Neurosciences, University of California San Francisco, San Francisco, California, USA.,Department of Physiology, University of California San Francisco, San Francisco, California, USA.,Kavli Institute for Fundamental Neuroscience, University of California San Francisco, San Francisco, California, USA
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6
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Seabrook TA, Burbridge TJ, Crair MC, Huberman AD. Architecture, Function, and Assembly of the Mouse Visual System. Annu Rev Neurosci 2018; 40:499-538. [PMID: 28772103 DOI: 10.1146/annurev-neuro-071714-033842] [Citation(s) in RCA: 165] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vision is the sense humans rely on most to navigate the world, make decisions, and perform complex tasks. Understanding how humans see thus represents one of the most fundamental and important goals of neuroscience. The use of the mouse as a model for parsing how vision works at a fundamental level started approximately a decade ago, ushered in by the mouse's convenient size, relatively low cost, and, above all, amenability to genetic perturbations. In the course of that effort, a large cadre of new and powerful tools for in vivo labeling, monitoring, and manipulation of neurons were applied to this species. As a consequence, a significant body of work now exists on the architecture, function, and development of mouse central visual pathways. Excitingly, much of that work includes causal testing of the role of specific cell types and circuits in visual perception and behavior-something rare to find in studies of the visual system of other species. Indeed, one could argue that more information is now available about the mouse visual system than any other sensory system, in any species, including humans. As such, the mouse visual system has become a platform for multilevel analysis of the mammalian central nervous system generally. Here we review the mouse visual system structure, function, and development literature and comment on the similarities and differences between the visual system of this and other model species. We also make it a point to highlight the aspects of mouse visual circuitry that remain opaque and that are in need of additional experimentation to enrich our understanding of how vision works on a broad scale.
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Affiliation(s)
- Tania A Seabrook
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305
| | - Timothy J Burbridge
- Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut 06520;
| | - Michael C Crair
- Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut 06520;
| | - Andrew D Huberman
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305.,Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California 94303; .,Bio-X, Stanford University, Stanford, California 94305
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7
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Abstract
Abstract
Axonal loss is an important process both during development and diseases of the nervous system. While the molecular mechanisms that mediate axonal loss are largely elusive, modern imaging technology affords an increasingly clear view of the cellular processes that allow nerve cells to shed individiual axon branches or even dismantle entire parts of their axonal projections. The present review discusses the characteristics of post-traumatic Wallerian degeneration, the process of axonal loss currently best understood. Subsequently, the properties of a number of recently discovered axonal loss phenomena are described. These phenomena explain some of the axonal loss that occurs locally after axon transection, during neuro-inflammatory insults, and as part of normal neurodevelopment.
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8
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Long-term depression-associated signaling is required for an in vitro model of NMDA receptor-dependent synapse pruning. Neurobiol Learn Mem 2016; 138:39-53. [PMID: 27794462 DOI: 10.1016/j.nlm.2016.10.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/20/2016] [Accepted: 10/25/2016] [Indexed: 02/06/2023]
Abstract
Activity-dependent pruning of synaptic contacts plays a critical role in shaping neuronal circuitry in response to the environment during postnatal brain development. Although there is compelling evidence that shrinkage of dendritic spines coincides with synaptic long-term depression (LTD), and that LTD is accompanied by synapse loss, whether NMDA receptor (NMDAR)-dependent LTD is a required step in the progression toward synapse pruning is still unknown. Using repeated applications of NMDA to induce LTD in dissociated rat neuronal cultures, we found that synapse density, as measured by colocalization of fluorescent markers for pre- and postsynaptic structures, was decreased irrespective of the presynaptic marker used, post-treatment recovery time, and the dendritic location of synapses. Consistent with previous studies, we found that synapse loss could occur without apparent net spine loss or cell death. Furthermore, synapse loss was unlikely to require direct contact with microglia, as the number of these cells was minimal in our culture preparations. Supporting a model by which NMDAR-LTD is required for synapse loss, the effect of NMDA on fluorescence colocalization was prevented by phosphatase and caspase inhibitors. In addition, gene transcription and protein translation also appeared to be required for loss of putative synapses. These data support the idea that NMDAR-dependent LTD is a required step in synapse pruning and contribute to our understanding of the basic mechanisms of this developmental process.
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9
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Leiwe MN, Hendry AC, Bard AD, Eglen SJ, Lowe AS, Thompson ID. Geniculo-Cortical Projection Diversity Revealed within the Mouse Visual Thalamus. PLoS One 2016; 11:e0144846. [PMID: 26727264 PMCID: PMC4699701 DOI: 10.1371/journal.pone.0144846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 11/24/2015] [Indexed: 12/02/2022] Open
Abstract
The mouse dorsal lateral geniculate nucleus (dLGN) is an intermediary between retina and primary visual cortex (V1). Recent investigations are beginning to reveal regional complexity in mouse dLGN. Using local injections of retrograde tracers into V1 of adult and neonatal mice, we examined the developing organisation of geniculate projection columns: the population of dLGN-V1 projection neurons that converge in cortex. Serial sectioning of the dLGN enabled the distribution of labelled projection neurons to be reconstructed and collated within a common standardised space. This enabled us to determine: the organisation of cells within the dLGN-V1 projection columns; their internal organisation (topology); and their order relative to V1 (topography). Here, we report parameters of projection columns that are highly variable in young animals and refined in the adult, exhibiting profiles consistent with shell and core zones of the dLGN. Additionally, such profiles are disrupted in adult animals with reduced correlated spontaneous activity during development. Assessing the variability between groups with partial least squares regression suggests that 4–6 cryptic lamina may exist along the length of the projection column. Our findings further spotlight the diversity of the mouse dLGN–an increasingly important model system for understanding the pre-cortical organisation and processing of visual information. Furthermore, our approach of using standardised spaces and pooling information across many animals will enhance future functional studies of the dLGN.
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Affiliation(s)
- Marcus N. Leiwe
- MRC Centre for Developmental Neurobiology, King’s College London, Guy’s Campus, London, United Kingdom
| | - Aenea C. Hendry
- MRC Centre for Developmental Neurobiology, King’s College London, Guy’s Campus, London, United Kingdom
| | - Andrew D. Bard
- MRC Centre for Developmental Neurobiology, King’s College London, Guy’s Campus, London, United Kingdom
| | - Stephen J. Eglen
- Cambridge Computational Biology Institute, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - Andrew S. Lowe
- MRC Centre for Developmental Neurobiology, King’s College London, Guy’s Campus, London, United Kingdom
- * E-mail: (IDT); (ASL)
| | - Ian D. Thompson
- MRC Centre for Developmental Neurobiology, King’s College London, Guy’s Campus, London, United Kingdom
- * E-mail: (IDT); (ASL)
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10
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Abstract
The assembly of functional neural circuits requires the combined action of progressive and regressive events. Regressive events encompass a variety of inhibitory developmental processes, including axon and dendrite pruning, which facilitate the removal of exuberant neuronal connections. Most axon pruning involves the removal of axons that had already made synaptic connections; thus, axon pruning is tightly associated with synapse elimination. In many instances, these developmental processes are regulated by the interplay between neurons and glial cells that act instructively during neural remodeling. Owing to the importance of axon and dendritic pruning, these remodeling events require precise spatial and temporal control, and this is achieved by a range of distinct molecular mechanisms. Disruption of these mechanisms results in abnormal pruning, which has been linked to brain dysfunction. Therefore, understanding the mechanisms of axon and dendritic pruning will be instrumental in advancing our knowledge of neural disease and mental disorders.
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Affiliation(s)
- Martin M Riccomagno
- Department of Cell Biology and Neuroscience, University of California, Riverside, California 92521;
| | - Alex L Kolodkin
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
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11
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Refinement of the retinogeniculate synapse by bouton clustering. Neuron 2014; 84:332-9. [PMID: 25284005 DOI: 10.1016/j.neuron.2014.08.059] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2014] [Indexed: 11/22/2022]
Abstract
Mammalian sensory circuits become refined over development in an activity-dependent manner. Retinal ganglion cell (RGC) axons from each eye first map to their target in the geniculate and then segregate into eye-specific layers by the removal and addition of axon branches. Once segregation is complete, robust functional remodeling continues as the number of afferent inputs to each geniculate neuron decreases from many to a few. It is widely assumed that large-scale axon retraction underlies this later phase of circuit refinement. On the contrary, RGC axons remain stable during functional pruning. Instead, presynaptic boutons grow in size and cluster during this process. Moreover, they exhibit dynamic spatial reorganization in response to sensory experience. Surprisingly, axon complexity decreases only after the completion of the thalamic critical period. Therefore, dynamic bouton redistribution along a broad axon backbone represents an unappreciated form of plasticity underlying developmental wiring and rewiring in the CNS.
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12
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Baier H. Synaptic laminae in the visual system: molecular mechanisms forming layers of perception. Annu Rev Cell Dev Biol 2013; 29:385-416. [PMID: 24099086 DOI: 10.1146/annurev-cellbio-101011-155748] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Synaptic connections between neurons form the basis for perception and behavior. Synapses are often clustered in space, forming stereotyped layers. In the retina and optic tectum, multiple such synaptic laminae are stacked on top of each other, giving rise to stratified neuropil regions in which each layer combines synapses responsive to a particular sensory feature. Recently, several cellular and molecular mechanisms that underlie the development of multilaminar arrays of synapses have been discovered. These mechanisms include neurite guidance and cell-cell recognition. Molecules of the Slit, Semaphorin, Netrin, and Hedgehog families, binding to their matching receptors, bring axons and dendrites into spatial register. These guidance cues may diffuse over short distances or bind to sheets of extracellular matrix, thus conditioning the local extracellular milieu, or are presented on the surface of cells bordering the future neuropil. In addition, mutual recognition of axons and dendrites through adhesion molecules with immunoglobulin domains ensures cell type-specific connections within a given layer. Thus, an elaborate genetic program assembles the parallel processing channels that underlie visual perception.
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Affiliation(s)
- Herwig Baier
- Genes - Circuits - Behavior, Max Planck Institute of Neurobiology, 82152 Martinsried near Munich, Germany;
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13
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Schafer DP, Lehrman EK, Kautzman AG, Koyama R, Mardinly AR, Yamasaki R, Ransohoff RM, Greenberg ME, Barres BA, Stevens B. Microglia sculpt postnatal neural circuits in an activity and complement-dependent manner. Neuron 2012; 74:691-705. [PMID: 22632727 PMCID: PMC3528177 DOI: 10.1016/j.neuron.2012.03.026] [Citation(s) in RCA: 2682] [Impact Index Per Article: 223.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2012] [Indexed: 02/06/2023]
Abstract
Microglia are the resident CNS immune cells and active surveyors of the extracellular environment. While past work has focused on the role of these cells during disease, recent imaging studies reveal dynamic interactions between microglia and synaptic elements in the healthy brain. Despite these intriguing observations, the precise function of microglia at remodeling synapses and the mechanisms that underlie microglia-synapse interactions remain elusive. In the current study, we demonstrate a role for microglia in activity-dependent synaptic pruning in the postnatal retinogeniculate system. We show that microglia engulf presynaptic inputs during peak retinogeniculate pruning and that engulfment is dependent upon neural activity and the microglia-specific phagocytic signaling pathway, complement receptor 3(CR3)/C3. Furthermore, disrupting microglia-specific CR3/C3 signaling resulted in sustained deficits in synaptic connectivity. These results define a role for microglia during postnatal development and identify underlying mechanisms by which microglia engulf and remodel developing synapses.
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Affiliation(s)
- Dorothy P Schafer
- Department of Neurology, F.M. Kirby Neurobiology Center, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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14
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Garrett AM, Burgess RW. Candidate molecular mechanisms for establishing cell identity in the developing retina. Dev Neurobiol 2012; 71:1258-72. [PMID: 21630473 DOI: 10.1002/dneu.20926] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the developing nervous system, individual neurons must occupy appropriate positions within circuits. This requires that these neurons recognize and form connections with specific pre- and postsynaptic partners. Cellular recognition is also required for the spacing of cell bodies and the arborization of dendrites, factors that determine the inputs onto a given neuron. These issues are particularly evident in the retina, where different types of neurons are evenly spaced relative to other cells of the same type. This establishes a reiterated columnar circuitry resembling the insect retina. Establishing these mosaic patterns requires that cells of a given type (homotypic cells) be able to sense their neighbors. Therefore, both synaptic specificity and mosaic spacing require cellular identifiers. In synaptic specificity, recognition often occurs between different types of cells in a pre- and postsynaptic pairing. In mosaic spacing, recognition is often occurring between different cells of the same type, orhomotypic self-recognition. Dendritic arborization can require recognition of different neurites of the same cell, or isoneuronal self-recognition. The retina is an extremely amenable system for studying the molecular identifiers that drive these various forms of recognition. The different neuronal types in the retina are well defined, and the genetic tools for marking cell types are increasingly available. In this review we will summarize retinal anatomy and describe cell types in the retina and how they are defined. We will then describe the requirements of a recognition code and discuss newly emerging candidate molecular mechanisms for recognition that may meet these requirements.
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15
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Epilepsy gene LGI1 regulates postnatal developmental remodeling of retinogeniculate synapses. J Neurosci 2012; 32:903-10. [PMID: 22262888 DOI: 10.1523/jneurosci.5191-11.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Retinogeniculate connections undergo postnatal refinement in the developing visual system. Here we report that non-ion channel epilepsy gene LGI1 (leucine-rich glioma-inactivated), mutated in human autosomal dominant lateral temporal lobe epilepsy (ADLTE), regulates postnatal pruning of retinal axons in visual relay thalamus. By introducing an ADLTE-associated truncated mutant LGI1 (836delC) or excess full-length LGI1 into transgenic mice, we found that mutant LGI1 blocks, whereas excess LGI1 accelerates, retinogeniculate axon pruning. The normal postnatal single fiber strengthening was arrested by mutant LGI1 and, contrastingly, was enhanced by excess wild-type LGI1. The maximum response of the retinogeniculate synapses, conversely, remained the same in mature LGI1 transgenic mice, indicating that mutant LGI1 blocks, whereas excess wild-type LGI1 promotes, weak axon fiber elimination. Heterozygous deletion of the LGI1 gene, as found in ADLTE patients, inhibited postnatal retinogeniculate synapse elimination, an effect similar to the ADLTE truncated mutant LGI1. The results identify sensory axon remodeling defects in a sensory aura-associated human epilepsy disorder.
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Hong YK, Chen C. Wiring and rewiring of the retinogeniculate synapse. Curr Opin Neurobiol 2011; 21:228-37. [PMID: 21558027 DOI: 10.1016/j.conb.2011.02.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 02/07/2011] [Accepted: 02/08/2011] [Indexed: 12/15/2022]
Abstract
The formation and refinement of synaptic circuits are areas of research that have fascinated neurobiologists for decades. A recurrent theme seen at many CNS synapses is that neuronal connections are at first imprecise, but refine and can be rearranged with time or with experience. Today, with the advent of new technologies to map and monitor neuronal circuits, it is worthwhile to revisit a powerful experimental model for examining the development and plasticity of synaptic circuits--the retinogeniculate synapse.
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Affiliation(s)
- Y Kate Hong
- Department of Neurology, F.M. Kirby Neurobiology Center, Children's Hospital, Boston, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, United States
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