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Nakagawa N, Iwasato T. Activity-dependent dendrite patterning in the postnatal barrel cortex. Front Neural Circuits 2024; 18:1409993. [PMID: 38827189 PMCID: PMC11140076 DOI: 10.3389/fncir.2024.1409993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 05/06/2024] [Indexed: 06/04/2024] Open
Abstract
For neural circuit construction in the brain, coarse neuronal connections are assembled prenatally following genetic programs, being reorganized postnatally by activity-dependent mechanisms to implement area-specific computational functions. Activity-dependent dendrite patterning is a critical component of neural circuit reorganization, whereby individual neurons rearrange and optimize their presynaptic partners. In the rodent primary somatosensory cortex (barrel cortex), driven by thalamocortical inputs, layer 4 (L4) excitatory neurons extensively remodel their basal dendrites at neonatal stages to ensure specific responses of barrels to the corresponding individual whiskers. This feature of barrel cortex L4 neurons makes them an excellent model, significantly contributing to unveiling the activity-dependent nature of dendrite patterning and circuit reorganization. In this review, we summarize recent advances in our understanding of the activity-dependent mechanisms underlying dendrite patterning. Our focus lays on the mechanisms revealed by in vivo time-lapse imaging, and the role of activity-dependent Golgi apparatus polarity regulation in dendrite patterning. We also discuss the type of neuronal activity that could contribute to dendrite patterning and hence connectivity.
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Affiliation(s)
- Naoki Nakagawa
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Japan
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Japan
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2
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Fahey L, Ali D, Donohoe G, Ó Broin P, Morris DW. Genes positively regulated by Mef2c in cortical neurons are enriched for common genetic variation associated with IQ and educational attainment. Hum Mol Genet 2023; 32:3194-3203. [PMID: 37672226 PMCID: PMC10630234 DOI: 10.1093/hmg/ddad142] [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: 04/06/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 09/07/2023] Open
Abstract
The myocyte enhancer factor 2 C (MEF2C) gene encodes a transcription factor important for neurogenesis and synapse development and contains common variants associated with intelligence (IQ) and educational attainment (EA). Here, we took gene expression data from the mouse cortex of a Mef2c mouse model with a heterozygous DNA binding-deficient mutation of Mef2c (Mef2c-het) and combined these data with MEF2C ChIP-seq data from cortical neurons and single-cell data from the mouse brain. This enabled us to create a set of genes that were differentially regulated in Mef2c-het mice, represented direct target genes of MEF2C and had elevated in expression in cortical neurons. We found this gene-set to be enriched for genes containing common genetic variation associated with IQ and EA. Genes within this gene-set that were down-regulated, i.e. have reduced expression in Mef2c-het mice versus controls, were specifically significantly enriched for both EA and IQ associated genes. These down-regulated genes were enriched for functionality in the adenylyl cyclase signalling system, which is known to positively regulate synaptic transmission and has been linked to learning and memory. Within the adenylyl cyclase signalling system, three genes regulated by MEF2C, CRHR1, RGS6, and GABRG3, are associated at genome-wide significant levels with IQ and/or EA. Our results indicate that genetic variation in MEF2C and its direct target genes within cortical neurons contribute to variance in cognition within the general population, and the molecular mechanisms involved include the adenylyl cyclase signalling system's role in synaptic function.
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Affiliation(s)
- Laura Fahey
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
- Discipline of Bioinformatics, School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Deema Ali
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Gary Donohoe
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Pilib Ó Broin
- Discipline of Bioinformatics, School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, H91 CF50, Ireland
| | - Derek W Morris
- Centre for Neuroimaging, Cognition and Genomics (NICOG), School of Biological and Chemical Sciences and School of Psychology, University of Galway, University Road, Galway, H91 CF50, Ireland
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3
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Oldham S, Ball G. A phylogenetically-conserved axis of thalamocortical connectivity in the human brain. Nat Commun 2023; 14:6032. [PMID: 37758726 PMCID: PMC10533558 DOI: 10.1038/s41467-023-41722-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
The thalamus enables key sensory, motor, emotive, and cognitive processes via connections to the cortex. These projection patterns are traditionally considered to originate from discrete thalamic nuclei, however recent work showing gradients of molecular and connectivity features in the thalamus suggests the organisation of thalamocortical connections occurs along a continuous dimension. By performing a joint decomposition of densely sampled gene expression and non-invasive diffusion tractography in the adult human thalamus, we define a principal axis of genetic and connectomic variation along a medial-lateral thalamic gradient. Projections along this axis correspond to an anterior-posterior cortical pattern and are aligned with electrophysiological properties of the cortex. The medial-lateral axis demonstrates phylogenetic conservation, reflects transitions in neuronal subtypes, and shows associations with neurodevelopment and common brain disorders. This study provides evidence for a supra-nuclear axis of thalamocortical organisation characterised by a graded transition in molecular properties and anatomical connectivity.
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Affiliation(s)
- Stuart Oldham
- Developmental Imaging, Murdoch Children's Research Institute, Parkville, VIC, Australia.
- The Turner Institute for Brain and Mental Health, School of Psychological Sciences and Monash Biomedical Imaging, Monash University, Clayton, VIC, Australia.
| | - Gareth Ball
- Developmental Imaging, Murdoch Children's Research Institute, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
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4
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Nakagawa N, Iwasato T. Golgi polarity shift instructs dendritic refinement in the neonatal cortex by mediating NMDA receptor signaling. Cell Rep 2023; 42:112843. [PMID: 37516101 DOI: 10.1016/j.celrep.2023.112843] [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: 03/07/2023] [Revised: 05/15/2023] [Accepted: 07/05/2023] [Indexed: 07/31/2023] Open
Abstract
Dendritic refinement is a critical component of activity-dependent neuronal circuit maturation, through which individual neurons establish specific connectivity with their target axons. Here, we demonstrate that the developmental shift of Golgi polarity is a key process in dendritic refinement. During neonatal development, the Golgi apparatus in layer 4 spiny stellate (SS) neurons in the mouse barrel cortex lose their original apical positioning and acquire laterally polarized distributions. This lateral Golgi polarity, which is oriented toward the barrel center, peaks on postnatal days 5-7 (P5-P7) and disappears by P15, which aligns with the developmental time course of SS neuron dendritic refinement. Genetic ablation of N-methyl-D-aspartate (NMDA) receptors, key players in dendritic refinement, disturbs the lateral Golgi polarity. Golgi polarity manipulation disrupts the asymmetric dendritic projection pattern and the primary-whisker-specific response of SS neurons. Our results elucidate activity-dependent Golgi dynamics and their critical role in developmental neuronal circuit refinement.
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Affiliation(s)
- Naoki Nakagawa
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan.
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan.
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5
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Recurrent rewiring of the adult hippocampal mossy fiber system by a single transcriptional regulator, Id2. Proc Natl Acad Sci U S A 2021; 118:2108239118. [PMID: 34599103 PMCID: PMC8501755 DOI: 10.1073/pnas.2108239118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2021] [Indexed: 12/03/2022] Open
Abstract
Neurons have an exceptional capacity to grow axons and form synaptic circuits during development but not later life. In adults, the lack of circuit formation may support retention of skilled actions and memories but also limits regeneration and repair after injuries and in disorders. Research on developing and damaged neurons has revealed many molecules that help circuit formation and regeneration, and yet factors that could induce axon growth and synapse formation in adult brain neurons remain elusive. Here, we searched for such key molecules and find one that alone can induce complete circuit formation. After engineering a new circuit in adult mice, we also looked into its function and relevance for memories. Circuit formation in the central nervous system has been historically studied during development, after which cell-autonomous and nonautonomous wiring factors inactivate. In principle, balanced reactivation of such factors could enable further wiring in adults, but their relative contributions may be circuit dependent and are largely unknown. Here, we investigated hippocampal mossy fiber sprouting to gain insight into wiring mechanisms in mature circuits. We found that sole ectopic expression of Id2 in granule cells is capable of driving mossy fiber sprouting in healthy adult mouse and rat. Mice with the new mossy fiber circuit solved spatial problems equally well as controls but appeared to rely on local rather than global spatial cues. Our results demonstrate reprogrammed connectivity in mature neurons by one defined factor and an assembly of a new synaptic circuit in adult brain.
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Massengill CI, Day-Cooney J, Mao T, Zhong H. Genetically encoded sensors towards imaging cAMP and PKA activity in vivo. J Neurosci Methods 2021; 362:109298. [PMID: 34339753 PMCID: PMC8659126 DOI: 10.1016/j.jneumeth.2021.109298] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 12/26/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) is a universal second messenger that plays a crucial role in diverse biological functions, ranging from transcription to neuronal plasticity, and from development to learning and memory. In the nervous system, cAMP integrates inputs from many neuromodulators across a wide range of timescales - from seconds to hours - to modulate neuronal excitability and plasticity in brain circuits during different animal behavioral states. cAMP signaling events are both cell-specific and subcellularly compartmentalized. The same stimulus may result in different, sometimes opposite, cAMP dynamics in different cells or subcellular compartments. Additionally, the activity of protein kinase A (PKA), a major cAMP effector, is also spatiotemporally regulated. For these reasons, many laboratories have made great strides toward visualizing the intracellular dynamics of cAMP and PKA. To date, more than 80 genetically encoded sensors, including original and improved variants, have been published. It is starting to become possible to visualize cAMP and PKA signaling events in vivo, which is required to study behaviorally relevant cAMP/PKA signaling mechanisms. Despite significant progress, further developments are needed to enhance the signal-to-noise ratio and practical utility of these sensors. This review summarizes the recent advances and challenges in genetically encoded cAMP and PKA sensors with an emphasis on in vivo imaging in the brain during behavior.
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Affiliation(s)
| | - Julian Day-Cooney
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Tianyi Mao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
| | - Haining Zhong
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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NMDA Receptor Enhances Correlation of Spontaneous Activity in Neonatal Barrel Cortex. J Neurosci 2021; 41:1207-1217. [PMID: 33372060 DOI: 10.1523/jneurosci.0527-20.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 12/09/2020] [Accepted: 12/14/2020] [Indexed: 01/07/2023] Open
Abstract
Correlated spontaneous activity plays critical role in the organization of neocortical circuits during development. However, cortical mechanisms regulating activity correlation are still elusive. In this study, using two-photon calcium imaging of the barrel cortex layer 4 (L4) in living neonatal mice, we found that NMDA receptors (NMDARs) in L4 neurons are important for enhancement of spontaneous activity correlation. Disruption of GluN1 (Grin1), an obligatory NMDAR subunit, in a sparse population of L4 neurons reduced activity correlation between GluN1 knock-out (GluN1KO) neuron pairs within a barrel. This reduction in activity correlation was even detected in L4 neuron pairs in neighboring barrels and most evident when either or both of neurons are located on the barrel edge. Our results provide evidence for the involvement of L4 neuron NMDARs in spatial organization of the spontaneous firing activity of L4 neurons in the neonatal barrel cortex.SIGNIFICANCE STATEMENT Precise wiring of the thalamocortical circuits is necessary for proper sensory information processing, and thalamus-derived correlated spontaneous activity is important for thalamocortical circuit formation. The molecular mechanisms involved in the correlated activity transfer from the thalamus to the neocortex are largely unknown. In vivo two-photon calcium imaging of the neonatal barrel cortex revealed that correlated spontaneous activity between layer four neurons is reduced by mosaic knock-out (KO) of the NMDA receptor (NMDAR) obligatory subunit GluN1. Our results suggest that the function of NMDARs in layer four neurons is necessary for the communication between presynaptic and postsynaptic partners during thalamocortical circuit formation.
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How the Barrel Cortex Became a Working Model for Developmental Plasticity: A Historical Perspective. J Neurosci 2021; 40:6460-6473. [PMID: 32817388 DOI: 10.1523/jneurosci.0582-20.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 01/08/2023] Open
Abstract
For half a century now, the barrel cortex of common laboratory rodents has been an exceptionally useful model for studying the formation of topographically organized maps, neural patterning, and plasticity, both in development and in maturity. We present a historical perspective on how barrels were discovered, and how thereafter, they became a workhorse for developmental neuroscientists and for studies on brain plasticity and activity-dependent modeling of brain circuits. What is particularly remarkable about this sensory system is a cellular patterning that is induced by signals derived from the sensory receptors surrounding the snout whiskers and transmitted centrally to the brainstem (barrelettes), the thalamus (barreloids), and the neocortex (barrels). Injury to the sensory receptors shortly after birth leads to predictable pattern alterations at all levels of the system. Mouse genetics have increased our understanding of how barrels are constructed and revealed the interplay of the molecular programs that direct axon growth and cell specification, with activity-dependent mechanisms. There is an ever-rising interest in this sensory system as a neurobiological model to study development of somatotopy, patterning, and plasticity at both the morphologic and physiological levels. This article is part of a group of articles commemorating the 50th anniversary of the Society for Neuroscience.
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Rao MS, Mizuno H. Elucidating mechanisms of neuronal circuit formation in layer 4 of the somatosensory cortex via intravital imaging. Neurosci Res 2020; 167:47-53. [PMID: 33309867 DOI: 10.1016/j.neures.2020.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 12/13/2022]
Abstract
The cerebral cortex has complex yet perfectly wired neuronal circuits that are important for high-level brain functions such as perception and cognition. The rodent's somatosensory system is widely used for understanding the mechanisms of circuit formation during early developmental periods. In this review, we summarize the developmental processes of circuit formation in layer 4 of the somatosensory cortex, and we describe the molecules involved in layer 4 circuit formation and neuronal activity-dependent mechanisms of circuit formation. We also introduce the dynamic mechanisms of circuit formation in layer 4 revealed by intravital two-photon imaging technologies, which include time-lapse imaging of neuronal morphology and calcium imaging of neuronal activity in newborn mice.
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Affiliation(s)
- Madhura S Rao
- Laboratory of Multi-dimensional Imaging, International Research Center for Medical Sciences (IRCMS), Kumamoto University, Kumamoto, 860-0811, Japan; Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan
| | - Hidenobu Mizuno
- Laboratory of Multi-dimensional Imaging, International Research Center for Medical Sciences (IRCMS), Kumamoto University, Kumamoto, 860-0811, Japan; Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan.
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10
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Iwasato T. In vivo imaging of neural circuit formation in the neonatal mouse barrel cortex. Dev Growth Differ 2020; 62:476-486. [DOI: 10.1111/dgd.12693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/13/2020] [Accepted: 09/27/2020] [Indexed: 01/21/2023]
Affiliation(s)
- Takuji Iwasato
- Laboratory of Mammalian Neural Circuits National Institute of Genetics Mishima Japan
- Department of Genetics SOKENDAI Mishima Japan
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11
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Seegobin SP, Heaton GR, Liang D, Choi I, Blanca Ramirez M, Tang B, Yue Z. Progress in LRRK2-Associated Parkinson's Disease Animal Models. Front Neurosci 2020; 14:674. [PMID: 32765209 PMCID: PMC7381130 DOI: 10.3389/fnins.2020.00674] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/02/2020] [Indexed: 12/19/2022] Open
Abstract
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most frequent cause of familial Parkinson's disease (PD). Several genetic manipulations of the LRRK2 gene have been developed in animal models such as rodents, Drosophila, Caenorhabditis elegans, and zebrafish. These models can help us further understand the biological function and derive potential pathological mechanisms for LRRK2. Here we discuss common phenotypic themes found in LRRK2-associated PD animal models, highlight several issues that should be addressed in future models, and discuss emerging areas to guide their future development.
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Affiliation(s)
- Steven P. Seegobin
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - George R. Heaton
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Dongxiao Liang
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neurology, Xiangya Hospital, Central South University, Hunan, China
| | - Insup Choi
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Marian Blanca Ramirez
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Hunan, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Hunan, China
| | - Zhenyu Yue
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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Vitalis T, Dauphinot L, Gressens P, Potier MC, Mariani J, Gaspar P. RORα Coordinates Thalamic and Cortical Maturation to Instruct Barrel Cortex Development. Cereb Cortex 2019; 28:3994-4007. [PMID: 29040410 DOI: 10.1093/cercor/bhx262] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The retinoic acid-related orphan receptor alpha (RORα) is well-known for its role in cerebellar development and maturation as revealed in staggerer mice. However, its potential involvement in the development of other brain regions has hardly been assessed. Here, we describe a new role of RORα in the development of primary somatosensory maps. Staggerer mice showed a complete disruption of barrels in the somatosensory cortex and of barreloids in the thalamus. This phenotype results from a severe reduction of thalamocortical axon (TCA) branching and a defective maturation of layer IV cortical neurons during postnatal development. Conditional deletion of RORα was conducted in the thalamus or the cortex to determine the specific contribution of RORα in each of these structures to these phenotypes. This showed that RORα is cell-autonomously required in the thalamus for the organization of TCAs into periphery-related clusters and in the somatosensory cortex for the dendritic maturation of layer IV neurons. Microarray analyses revealed that Sema7a, Neph, and Adcy8 are RORα regulated genes that could be implicated in TCA and cortical maturation. Overall, our study outlines a new role of RORα for the coordinated maturation of the somatosensory thalamus and cortex during the assembly of columnar barrel structures.
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Affiliation(s)
- Tania Vitalis
- PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
- Université Pierre et Marie Curie, Sorbonne Université, Paris, France
| | - Luce Dauphinot
- Université Pierre et Marie Curie, Sorbonne Université, Paris, France
- CNRS UMR 7225, INSERM U1127, Institut du Cerveau et de la Moelle, Paris, France
| | - Pierre Gressens
- PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Marie-Claude Potier
- Université Pierre et Marie Curie, Sorbonne Université, Paris, France
- CNRS UMR 7225, INSERM U1127, Institut du Cerveau et de la Moelle, Paris, France
| | - Jean Mariani
- Université Pierre et Marie Curie, Sorbonne Université, Paris, France
- CNRS, UMR 8256, Institut de Biologie de Paris Seine (IBPS), Biological adaptation and ageing (B2A), Team Brain Development, Repair and Ageing, Paris, France
- APHP, DHU FAST, Institut de la Longévité, Ivry-Sur-Seine, France
| | - Patricia Gaspar
- Université Pierre et Marie Curie, Sorbonne Université, Paris, France
- INSERM, UMR-S839, Institut du Fer à Moulin, Paris, France
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13
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Hatanaka Y, Kawasaki T, Abe T, Shioi G, Kohno T, Hattori M, Sakakibara A, Kawaguchi Y, Hirata T. Semaphorin 6A-Plexin A2/A4 Interactions with Radial Glia Regulate Migration Termination of Superficial Layer Cortical Neurons. iScience 2019; 21:359-374. [PMID: 31698249 PMCID: PMC6889767 DOI: 10.1016/j.isci.2019.10.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 08/30/2019] [Accepted: 10/16/2019] [Indexed: 12/01/2022] Open
Abstract
Precise regulation of neuronal migration termination is crucial for the establishment of brain cytoarchitectures. However, little is known about how neurons terminate migration. Here we focused on interactions between migrating cortical neurons and their substrates, radial glial (RG) cells, and analyzed the role of Plexin A2 and A4 (PlxnA2/A4) receptors and their repulsive ligand, Semaphorin 6A (Sema6A), for this process. In both PlxnA2/A4 double-knockout and Sema6A mutant mice, the outermost cortical plate neurons ectopically invade layer 1 at a stage when they should reach their destinations. PlxnA2/A4 proteins are abundantly expressed on their leading processes, whereas Sema6A mRNA is enriched in RG cell somata. Cell-targeted gene expression and conditional knockouts indicate critical roles for these molecules. We hypothesize that the timely appearance of repulsive signaling mediated by Sema6A–PlxnA2/A4 weakens migrating neuron–RG cell interactions, leading to migration termination. Loss of PlxnA2/A4 results in superficial layer neurons invading layer 1 PlxnA2/A4 works cell autonomously to settle these neurons properly Lack of Sema6A in radial glial cells causes similar mispositioning of these neurons Sema6A–PlxnA2/A4 signaling determines settling position of superficial layer neurons
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Affiliation(s)
- Yumiko Hatanaka
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; Division of Cerebral Circuitry, National Institute for Physiological Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan; College of Life and Health Sciences, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
| | - Takahiko Kawasaki
- Brain Function Laboratory, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Takaya Abe
- Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima Minami-machi, Chuou-ku, Kobe, Hyogo 650-0047, Japan
| | - Go Shioi
- Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima Minami-machi, Chuou-ku, Kobe, Hyogo 650-0047, Japan
| | - Takao Kohno
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
| | - Mitsuharu Hattori
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, Aichi 467-8603, Japan
| | - Akira Sakakibara
- College of Life and Health Sciences, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Yasuo Kawaguchi
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Tatsumi Hirata
- Brain Function Laboratory, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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14
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Zhang M, Lu M, Huang H, Liu X, Su H, Li H. Maturation of thalamocortical synapses in the somatosensory cortex depends on neocortical AKAP5 expression. Neurosci Lett 2019; 709:134374. [PMID: 31310785 DOI: 10.1016/j.neulet.2019.134374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/01/2019] [Accepted: 07/09/2019] [Indexed: 11/18/2022]
Abstract
Sensory cortex topographic maps consist of organized arrays of thalamocortical afferents (TCAs) that project into distinct areas of the cortex. Formation of topographic maps in sensory cortices is a prerequisite for functional maturation of the neocortex. Studies have shown that the formation of topographic maps and the maturation of thalamocortical synapses in the somatosensory cortex depend on the cyclic adenosine 5'-monophosphate-(cAMP)-protein kinase A (PKA) signaling pathway. AKAP5 is a scaffold protein (also called AKAP79 in humans or AKAP150 in rodents; AKAP79/150) that serves as a signaling hub that links cAMP and PKA signaling. Whether AKAP5 plays a role in topographic map formation and the maturation of thalamocortical synapses during development of the somatosensory cortex is still unknown. Here, we generated cortex-specific AKAP5-knockout mice (CxAKAP5KO) to examine its roles in somatosensory cortex development. We found that CxAKAP5KO mice displayed impaired cortical barrel maps. Electrophysiological recordings showed that the AMPA/NMDA ratio was reduced, and silent synapses were increased in thalamocortical synapses of CxAKAP5KO mice during postnatal development. Morphological analysis of layer IV cortical neurons demonstrated that dendritic refinement of these neurons was abnormal. These results indicate that AKAP5 is necessary for both topographic map formation and maturation of thalamocortical synapses as well as morphological development of cortical neurons in the somatosensory cortex.
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Affiliation(s)
- Min Zhang
- Department of Physiology, Anhui Medical College, Anhui 230601, China
| | - Meifang Lu
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Hao Huang
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Xiaoyan Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China
| | - Haoran Su
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Hong Li
- Department of Histology and Embryology, School of Basic Medical Sciences, Anhui Medical University, Anhui 230032, China.
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Tatsukawa T, Raveau M, Ogiwara I, Hattori S, Miyamoto H, Mazaki E, Itohara S, Miyakawa T, Montal M, Yamakawa K. Scn2a haploinsufficient mice display a spectrum of phenotypes affecting anxiety, sociability, memory flexibility and ampakine CX516 rescues their hyperactivity. Mol Autism 2019; 10:15. [PMID: 30962870 PMCID: PMC6437867 DOI: 10.1186/s13229-019-0265-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/06/2019] [Indexed: 01/13/2023] Open
Abstract
Background Mutations of the SCN2A gene encoding a voltage-gated sodium channel alpha-II subunit Nav1.2 are associated with neurological disorders such as epilepsy, autism spectrum disorders, intellectual disability, and schizophrenia. However, causal relationships and pathogenic mechanisms underlying these neurological defects, especially social and psychiatric features, remain to be elucidated. Methods We investigated the behavior of mice with a conventional or conditional deletion of Scn2a in a comprehensive test battery including open field, elevated plus maze, light-dark box, three chambers, social dominance tube, resident-intruder, ultrasonic vocalization, and fear conditioning tests. We further monitored the effects of the positive allosteric modulator of AMPA receptors CX516 on these model mice. Results Conventional heterozygous Scn2a knockout mice (Scn2aKO/+) displayed novelty-induced exploratory hyperactivity and increased rearing. The increased vertical activity was reproduced by heterozygous inactivation of Scn2a in dorsal-telencephalic excitatory neurons but not in inhibitory neurons. Moreover, these phenotypes were rescued by treating Scn2aKO/+ mice with CX516. Additionally, Scn2aKO/+ mice displayed mild social behavior impairment, enhanced fear conditioning, and deficient fear extinction. Neuronal activity was intensified in the medial prefrontal cortex of Scn2aKO/+ mice, with an increase in the gamma band. Conclusions Scn2aKO/+ mice exhibit a spectrum of phenotypes commonly observed in models of schizophrenia and autism spectrum disorder. Treatment with the CX516 ampakine, which ameliorates hyperactivity in these mice, could be a potential therapeutic strategy to rescue some of the disease phenotypes. Electronic supplementary material The online version of this article (10.1186/s13229-019-0265-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tetsuya Tatsukawa
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan
| | - Matthieu Raveau
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan
| | - Ikuo Ogiwara
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan.,2Department of Physiology, Nippon Medical School, Bunkyo-ku, Tokyo, 113-8602 Japan
| | - Satoko Hattori
- 3Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake-shi, Aichi 470-1192 Japan
| | - Hiroyuki Miyamoto
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan
| | - Emi Mazaki
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan
| | - Shigeyoshi Itohara
- 4Laboratory for Behavioral Genetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan.,5FIRST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 Japan
| | - Tsuyoshi Miyakawa
- 3Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake-shi, Aichi 470-1192 Japan
| | - Mauricio Montal
- 6Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093 USA
| | - Kazuhiro Yamakawa
- 1Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198 Japan
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16
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Simi A, Studer M. Developmental genetic programs and activity-dependent mechanisms instruct neocortical area mapping. Curr Opin Neurobiol 2018; 53:96-102. [DOI: 10.1016/j.conb.2018.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/07/2018] [Accepted: 06/14/2018] [Indexed: 12/18/2022]
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17
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Differential dynamics of cortical neuron dendritic trees revealed by long-term in vivo imaging in neonates. Nat Commun 2018; 9:3106. [PMID: 30082783 PMCID: PMC6078955 DOI: 10.1038/s41467-018-05563-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 07/10/2018] [Indexed: 12/13/2022] Open
Abstract
Proper neuronal circuit function relies on precise dendritic projection, which is established through activity-dependent refinement during early postnatal development. Here we revealed dynamics of dendritic refinement in the mammalian brain by conducting long-term imaging of the neonatal mouse barrel cortex. By “retrospective” analyses, we identified “prospective” barrel-edge spiny stellate (SS) neurons in early neonates, which had an apical dendrite and primitive basal dendrites (BDs). These neurons retracted the apical dendrite gradually and established strong BD orientation bias through continuous “dendritic tree” turnover. A greater chance of survival was given to BD trees emerged in the barrel-center side, where thalamocortical axons (TCAs) cluster. When the spatial bias of TCA inputs to SS neurons was lost, BD tree turnover was suppressed, and most BD trees became stable and elaborated mildly. Thus, barrel-edge SS neurons could establish the characteristic BD projection pattern through differential dynamics of dendritic trees induced by spatially biased inputs. Layer 4 stellate neurons in barrel cortex have a characteristic dendritic pattern. Here, the authors conduct long-term imaging from postnatal day 3–6 to show that an orientation bias is established through dendritic tree turnover and selective elaboration, which may be induced by biased thalamocortical inputs.
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18
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Ogiwara I, Miyamoto H, Tatsukawa T, Yamagata T, Nakayama T, Atapour N, Miura E, Mazaki E, Ernst SJ, Cao D, Ohtani H, Itohara S, Yanagawa Y, Montal M, Yuzaki M, Inoue Y, Hensch TK, Noebels JL, Yamakawa K. Nav1.2 haplodeficiency in excitatory neurons causes absence-like seizures in mice. Commun Biol 2018; 1:96. [PMID: 30175250 PMCID: PMC6115194 DOI: 10.1038/s42003-018-0099-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mutations in the SCN2A gene encoding a voltage-gated sodium channel Nav1.2 are associated with epilepsies, intellectual disability, and autism. SCN2A gain-of-function mutations cause early-onset severe epilepsies, while loss-of-function mutations cause autism with milder and/or later-onset epilepsies. Here we show that both heterozygous Scn2a-knockout and knock-in mice harboring a patient-derived nonsense mutation exhibit ethosuximide-sensitive absence-like seizures associated with spike-and-wave discharges at adult stages. Unexpectedly, identical seizures are reproduced and even more prominent in mice with heterozygous Scn2a deletion specifically in dorsal-telencephalic (e.g., neocortical and hippocampal) excitatory neurons, but are undetected in mice with selective Scn2a deletion in inhibitory neurons. In adult cerebral cortex of wild-type mice, most Nav1.2 is expressed in excitatory neurons with a steady increase and redistribution from proximal (i.e., axon initial segments) to distal axons. These results indicate a pivotal role of Nav1.2 haplodeficiency in excitatory neurons in epilepsies of patients with SCN2A loss-of-function mutations.
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Affiliation(s)
- Ikuo Ogiwara
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Department of Physiology, Nippon Medical School, Tokyo, 113-8602, Japan
| | - Hiroyuki Miyamoto
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Laboratory for Neuronal Circuit Development, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,PRESTO, Japan Science and Technology Agency, Saitama, 332-0012, Japan
| | - Tetsuya Tatsukawa
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan
| | - Tetsushi Yamagata
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan
| | - Tojo Nakayama
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Department of Pediatrics, Tohoku University School of Medicine, Sendai, 980-8574, Japan.,Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Nafiseh Atapour
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Laboratory for Neuronal Circuit Development, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Department of Medicine (Royal Melbourne Hospital), Melbourne Brain Centre, University of Melbourne, Parkville, VIC, 3050, Australia
| | - Eriko Miura
- Department of Physiology, School of Medicine, Keio University, Tokyo, 160-8582, Japan
| | - Emi Mazaki
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan
| | - Sara J Ernst
- Department of Neurology, Baylor College of Medicine, Houston, TX, 77030, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Dezhi Cao
- National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, 420-8688, Japan.,Neurology Department, Shenzhen Children's Hospital, 518026, Guangdong, China
| | - Hideyuki Ohtani
- National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, 420-8688, Japan
| | - Shigeyoshi Itohara
- Laboratory for Behavioral Genetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,FIRST, Japan Science and Technology Agency, Saitama, 332-0012, Japan
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, 371-8511, Japan.,CREST, Japan Science and Technology Agency, Saitama, 332-0012, Japan
| | - Mauricio Montal
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Michisuke Yuzaki
- Department of Physiology, School of Medicine, Keio University, Tokyo, 160-8582, Japan
| | - Yushi Inoue
- National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, 420-8688, Japan
| | - Takao K Hensch
- Laboratory for Neuronal Circuit Development, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.,Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA, 02138, USA.,Department of Neurology, FM Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX, 77030, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kazuhiro Yamakawa
- Laboratory for Neurogenetics, RIKEN Center for Brain Science, Wako, Saitama, 351-0198, Japan.
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19
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Gaspar P, Renier N. Constraints on somatosensory map development: mutants lead the way. Curr Opin Neurobiol 2018; 53:43-49. [PMID: 29753205 DOI: 10.1016/j.conb.2018.04.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 12/31/2022]
Abstract
In the rodent somatosensory system, the disproportionally large whisker representation and their specialization into barrel-shaped units in the different sensory relays has offered experimentalists with an ideal tool to identify mechanisms involved in brain map formation. These combine three intertwined constraints: Firstly, fasciculation of the incoming axons; secondly, early neural activity; finally, molecular patterning. Sophisticated genetic manipulations in mice have now allowed dissecting these mechanisms with greater accuracy. Here we discuss some recent papers that provided novel insights into how these different mapping rules and constraints interact to shape the barrel map.
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Affiliation(s)
- Patricia Gaspar
- Inserm, U839, Institut du Fer à Moulin, Paris, France; Sorbonne Universités, Paris, France.
| | - Nicolas Renier
- Sorbonne Universités, Paris, France; Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, Inserm, CNRS, Paris, France
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20
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Antón-Bolaños N, Espinosa A, López-Bendito G. Developmental interactions between thalamus and cortex: a true love reciprocal story. Curr Opin Neurobiol 2018; 52:33-41. [PMID: 29704748 DOI: 10.1016/j.conb.2018.04.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/13/2018] [Indexed: 01/08/2023]
Abstract
The developmental programs that control the specification of cortical and thalamic territories are maintained largely as independent processes. However, bulk of evidence demonstrates the requirement of the reciprocal interactions between cortical and thalamic neurons as key for the correct development of functional thalamocortical circuits. This reciprocal loop of connections is essential for sensory processing as well as for the execution of complex sensory-motor tasks. Here, we review recent advances in our understanding of how mutual collaborations between both brain regions define area patterning and cell differentiation in the thalamus and cortex.
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Affiliation(s)
- Noelia Antón-Bolaños
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant 03550, Spain
| | - Ana Espinosa
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant 03550, Spain
| | - Guillermina López-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant 03550, Spain.
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21
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Tatsukawa T, Ogiwara I, Mazaki E, Shimohata A, Yamakawa K. Impairments in social novelty recognition and spatial memory in mice with conditional deletion of Scn1a in parvalbumin-expressing cells. Neurobiol Dis 2018; 112:24-34. [PMID: 29337050 DOI: 10.1016/j.nbd.2018.01.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/23/2017] [Accepted: 01/09/2018] [Indexed: 11/16/2022] Open
Abstract
Loss of function mutations in the SCN1A gene, which encodes the voltage-gated sodium channel Nav1.1, have been described in the majority of Dravet syndrome patients presenting with epileptic seizures, hyperactivity, autistic traits, and cognitive decline. We previously reported predominant Nav1.1 expression in parvalbumin-expressing (PV+) inhibitory neurons in juvenile mouse brain and observed epileptic seizures in mice with selective deletion of Scn1a in PV+ cells mediated by PV-Cre transgene expression (Scn1afl/+/PV-Cre-TG). Here we investigate the behavior of Scn1afl/+/PV-Cre-TG mice using a comprehensive battery of behavioral tests. We observed that Scn1afl/+/PV-Cre-TG mice display hyperactive behavior, impaired social novelty recognition, and altered spatial memory. We also generated Scn1afl/+/SST-Cre-KI mice with a selective Scn1a deletion in somatostatin-expressing (SST+) inhibitory neurons using an SST-IRES-Cre knock-in driver line. We observed that Scn1afl/+/SST-Cre-KI mice display no spontaneous convulsive seizures and that Scn1afl/+/SST-Cre-KI mice have a lowered threshold temperature for hyperthermia-induced seizures, although their threshold values are much higher than those of Scn1afl/+/PV-Cre-TG mice. We finally show that Scn1afl/+/SST-Cre-KI mice exhibited no noticeable behavioral abnormalities. These observations suggest that impaired Nav1.1 function in PV+ interneurons is critically involved in the pathogenesis of hyperactivity, autistic traits, and cognitive decline, as well as epileptic seizures, in Dravet syndrome.
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Affiliation(s)
- Tetsuya Tatsukawa
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Ikuo Ogiwara
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Department of Physiology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Emi Mazaki
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Atsushi Shimohata
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Kazuhiro Yamakawa
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
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22
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Miyamoto H, Shimohata A, Abe M, Abe T, Mazaki E, Amano K, Suzuki T, Tatsukawa T, Itohara S, Sakimura K, Yamakawa K. Potentiation of excitatory synaptic transmission ameliorates aggression in mice with Stxbp1 haploinsufficiency. Hum Mol Genet 2017; 26:4961-4974. [DOI: 10.1093/hmg/ddx379] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/09/2017] [Indexed: 11/13/2022] Open
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23
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Spinal RacGAP α-Chimaerin Is Required to Establish the Midline Barrier for Proper Corticospinal Axon Guidance. J Neurosci 2017; 37:7682-7699. [PMID: 28747385 DOI: 10.1523/jneurosci.3123-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 05/11/2017] [Accepted: 06/27/2017] [Indexed: 12/17/2022] Open
Abstract
In the developing CNS, the midline barrier, which comprises guidance molecule-expressing midline glial somata and processes, plays a pivotal role in midline axon guidance. Accumulating evidence has revealed the molecular mechanisms by which the midline barrier ensures proper midline guidance for axons. In contrast, the mechanisms for establishing the midline barrier remain obscure. Here, we report that Rac-specific GTPase-activating protein (RacGAP) α-chimaerin is required for both axonal repulsion at and establishment of the midline barrier in the spinal cord. We generated cortex-specific and spinal-cord-specific α-chimaerin gene (Chn1) knock-out mice (Cx-Chn1KO and Sp-Chn1KO mice, respectively) and found that both showed aberrant corticospinal tract (CST) axon midline crossing in the spinal cord. Strikingly, Sp-Chn1KO mice had breaks (holes) in the ephrinB3(+) spinal midline barrier and EphA4(+) CST axons aberrantly crossed the midline through these holes. During normal embryonic development, EphA4(+) spinal cells are located in juxta-midline areas but are excluded from the midline. In contrast, in Chn1KO embryos, several EphA4(+) cells were aberrantly relocated into the midline and the midline barrier was broken around these cells. Similarly, the spinal cord midline of Epha4KO mice was invaded by juxta-midline EphA4 cells (i.e., Epha4 promoter-active cells) during the embryonic stage and holes were formed in the midline barrier. Juxta-midline EphA4 cells in the spinal cord expressed α-chimaerin. We propose that spinal α-chimaerin aids in establishing an intact spinal midline barrier by mediating juxta-midline EphA4(+) cell repulsion, thus preventing these cells from breaking into the ephrinB3(+) midline barrier.SIGNIFICANCE STATEMENT The midline barrier plays a critical role in midline axon guidance, which is fundamental to the formation of neural circuits that are responsible for proper left-right coordination of the body. Studies have revealed some of the mechanisms underlying how the midline barrier navigates axons. In contrast, the establishment of the midline barrier during embryonic development remains unclear. In this study, we determined that α-chimaerin is required for the formation of an intact midline barrier. Spinal-cord-specific α-chimaerin knock-out mice had spinal midline barriers with numerous breaks (holes), through which corticospinal axons aberrantly crossed the midline. We propose that α-chimaerin protects the midline barrier by mediating cell-repulsive signaling in juxta-midline cells, which prevents these cells from invading the midline.
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mGluR5 Exerts Cell-Autonomous Influences on the Functional and Anatomical Development of Layer IV Cortical Neurons in the Mouse Primary Somatosensory Cortex. J Neurosci 2017; 36:8802-14. [PMID: 27559164 DOI: 10.1523/jneurosci.1224-16.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/13/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Glutamate neurotransmission refines synaptic connections to establish the precise neural circuits underlying sensory processing. Deleting metabotropic glutamate receptor 5 (mGluR5) in mice perturbs cortical somatosensory map formation in the primary somatosensory (S1) cortex at both functional and anatomical levels. To examine the cell-autonomous influences of mGluR5 signaling in the morphological and functional development of layer IV spiny stellate glutamatergic neurons receiving sensory input, mGluR5 genetic mosaic mice were generated through in utero electroporation. In the S1 cortex of these mosaic brains, we found that most wild-type neurons were located in barrel rings encircling thalamocortical axon (TCA) clusters while mGluR5 knock-out (KO) neurons were placed in the septal area, the cell-sparse region separating barrels. These KO neurons often displayed a symmetrical dendritic morphology with increased dendritic complexity, in contrast to the polarized pattern of wild-type neurons. The dendritic spine density of mGluR5 KO spiny stellate neurons was significantly higher than in wild-type neurons. Whole-cell electrophysiological recordings detected a significant increase in the frequencies of spontaneous and miniature excitatory postsynaptic events in mGluR5 KO neurons compared with neighboring wild-type neurons. Our mosaic analysis provides strong evidence supporting the cell-autonomous influence of mGluR5 signaling on the functional and anatomical development of cortical glutamatergic neurons. Specifically, mGluR5 is required in cortical glutamatergic neurons for the following processes: (1) the placement of cortical glutamatergic neurons close to TCA clusters; (2) the regulation of dendritic complexity and outgrowth toward TCA clusters; (3) spinogenesis; and (4) tuning of excitatory inputs. SIGNIFICANCE STATEMENT Glutamatergic transmission plays a critical role in cortical circuit formation. Its dysfunction has been proposed as a core factor in the etiology of many neurological diseases. Here we conducted mosaic analysis to reveal the cell-autonomous role of the metabotropic glutamate receptor 5 (mGluR5). We found that mGluR5 is required for several key steps in wiring up the thalamocortical connections to form the cortical somatosensory map. mGluR5-dependent processes during early postnatal brain development affect the following: (1) placement of activity-directed cortical neurons; (2) regulation of polarized dendritic outgrowth toward thalamocortical axons relaying sensory information, (3) synaptogenesis; and (4) development of functional connectivity in spiny stellate neurons. Perturbing mGluR5 expression could lead to abnormal neuronal circuits, which may contribute to neurological and psychiatric disease.
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25
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Greig LC, Woodworth MB, Greppi C, Macklis JD. Ctip1 Controls Acquisition of Sensory Area Identity and Establishment of Sensory Input Fields in the Developing Neocortex. Neuron 2017; 90:261-77. [PMID: 27100196 DOI: 10.1016/j.neuron.2016.03.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 11/16/2015] [Accepted: 03/07/2016] [Indexed: 12/19/2022]
Abstract
While transcriptional controls over the size and relative position of cortical areas have been identified, less is known about regulators that direct acquisition of area-specific characteristics. Here, we report that the transcription factor Ctip1 functions in primary sensory areas to repress motor and activate sensory programs of gene expression, enabling establishment of sharp molecular boundaries defining functional areas. In Ctip1 mutants, abnormal gene expression leads to aberrantly motorized corticocortical and corticofugal output connectivity. Ctip1 critically regulates differentiation of layer IV neurons, and selective loss of Ctip1 in cortex deprives thalamocortical axons of their receptive "sensory field" in layer IV, which normally provides a tangentially and radially defined compartment of dedicated synaptic territory. Therefore, although thalamocortical axons invade appropriate cortical regions, they are unable to organize into properly configured sensory maps. Together, these data identify Ctip1 as a critical control over sensory area development.
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Affiliation(s)
- Luciano C Greig
- Department of Stem Cell and Regenerative Biology, Center for Brain Science and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Harvard Medical School, Boston, MA 02215, USA
| | - Mollie B Woodworth
- Department of Stem Cell and Regenerative Biology, Center for Brain Science and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Harvard Medical School, Boston, MA 02215, USA
| | - Chloé Greppi
- Department of Stem Cell and Regenerative Biology, Center for Brain Science and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Harvard Medical School, Boston, MA 02215, USA
| | - Jeffrey D Macklis
- Department of Stem Cell and Regenerative Biology, Center for Brain Science and Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Harvard Medical School, Boston, MA 02215, USA.
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Martini FJ, Moreno-Juan V, Filipchuk A, Valdeolmillos M, López-Bendito G. Impact of thalamocortical input on barrel cortex development. Neuroscience 2017; 368:246-255. [PMID: 28412498 DOI: 10.1016/j.neuroscience.2017.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 03/31/2017] [Accepted: 04/03/2017] [Indexed: 01/22/2023]
Abstract
The development of cortical maps requires the balanced interaction between genetically determined programs and input/activity-dependent signals generated spontaneously or triggered from the environment. The somatosensory pathway of mice provides an excellent scenario to study cortical map development because of its highly organized cytoarchitecture, known as the barrel field. This precise organization makes evident even small alterations in the cortical map layout. In this review, we will specially focus on the thalamic factors that control barrel field development. We will summarize the role of thalamic input integration and identity, neurotransmission and spontaneous activity in cortical map formation and early cross-modal plasticity.
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Affiliation(s)
- Francisco J Martini
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
| | - Verónica Moreno-Juan
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Anton Filipchuk
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Miguel Valdeolmillos
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain
| | - Guillermina López-Bendito
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas (UMH-CSIC), Sant Joan d'Alacant, Spain.
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Harrington AJ, Raissi A, Rajkovich K, Berto S, Kumar J, Molinaro G, Raduazzo J, Guo Y, Loerwald K, Konopka G, Huber KM, Cowan CW. MEF2C regulates cortical inhibitory and excitatory synapses and behaviors relevant to neurodevelopmental disorders. eLife 2016; 5. [PMID: 27779093 PMCID: PMC5094851 DOI: 10.7554/elife.20059] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/11/2016] [Indexed: 12/23/2022] Open
Abstract
Numerous genetic variants associated with MEF2C are linked to autism, intellectual disability (ID) and schizophrenia (SCZ) – a heterogeneous collection of neurodevelopmental disorders with unclear pathophysiology. MEF2C is highly expressed in developing cortical excitatory neurons, but its role in their development remains unclear. We show here that conditional embryonic deletion of Mef2c in cortical and hippocampal excitatory neurons (Emx1-lineage) produces a dramatic reduction in cortical network activity in vivo, due in part to a dramatic increase in inhibitory and a decrease in excitatory synaptic transmission. In addition, we find that MEF2C regulates E/I synapse density predominantly as a cell-autonomous, transcriptional repressor. Analysis of differential gene expression in Mef2c mutant cortex identified a significant overlap with numerous synapse- and autism-linked genes, and the Mef2c mutant mice displayed numerous behaviors reminiscent of autism, ID and SCZ, suggesting that perturbing MEF2C function in neocortex can produce autistic- and ID-like behaviors in mice. DOI:http://dx.doi.org/10.7554/eLife.20059.001 Abnormal development of the brain contributes to intellectual disability, as well as to a number of psychiatric disorders, including schizophrenia and autism. As the brain develops, neurons establish connections with one another called synapses, which are either excitatory or inhibitory. At excitatory synapses, an electrical signal in the first cell increases the likelihood that the second cell will also produce an electrical signal. At inhibitory synapses, electrical activity in the first cell reduces the chances of the second cell producing an electrical signal. An imbalance between excitatory and inhibitory activity is one of the factors thought to give rise to neurodevelopmental disorders. Many individuals with schizophrenia, autism or intellectual disability possess mutations in, or near, a gene called MEF2C. This gene, which is active in both excitatory and inhibitory neurons, encodes a protein that regulates the activity of many other genes during brain development. Harrington, Raissi et al. therefore hypothesized that alterations in MEF2C might predispose individuals to neurodevelopmental disorders by disrupting the balance of excitatory and inhibitory synapses in the developing brain. To test this idea, Harrington, Raissi et al. generated mice that lack the Mef2c gene in a large proportion of their neurons throughout development. As predicted, the animals showed an imbalance of excitatory and inhibitory synapses in the brain’s outer layer, the cortex. They also displayed changes in behavior like those seen in autism. These included a loss of interest in social interaction and a reduction in vocalizations, suggesting impaired communication. Other behavioral changes included hyperactivity, repetitive movements and severe learning impairments: all features commonly observed in human neurodevelopmental disorders. The next challenge is to understand when, where and how MEF2C acts in the cortex to shape the balance of excitatory and inhibitory connections. Once this is known, further studies can test whether disrupting these processes leads directly to behaviors characteristic of autism, schizophrenia and intellectual disability. This may lead to the development of new drugs that can reverse or improve the symptoms of these conditions in affected individuals. DOI:http://dx.doi.org/10.7554/eLife.20059.002
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Affiliation(s)
- Adam J Harrington
- Department of Neurosciences, Medical University of South Carolina, Charleston, United States.,Department of Psychiatry, Harvard Medical School, Belmont, United States
| | - Aram Raissi
- Department of Psychiatry, Harvard Medical School, Belmont, United States
| | - Kacey Rajkovich
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Stefano Berto
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Jaswinder Kumar
- Department of Psychiatry, Harvard Medical School, Belmont, United States.,Medical Scientist Training Program, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Gemma Molinaro
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Jonathan Raduazzo
- Department of Psychiatry, Harvard Medical School, Belmont, United States
| | - Yuhong Guo
- Department of Psychiatry, Harvard Medical School, Belmont, United States
| | - Kris Loerwald
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Genevieve Konopka
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Kimberly M Huber
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Christopher W Cowan
- Department of Neurosciences, Medical University of South Carolina, Charleston, United States.,Department of Psychiatry, Harvard Medical School, Belmont, United States
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28
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Luo W, Mizuno H, Iwata R, Nakazawa S, Yasuda K, Itohara S, Iwasato T. Supernova: A Versatile Vector System for Single-Cell Labeling and Gene Function Studies in vivo. Sci Rep 2016; 6:35747. [PMID: 27775045 PMCID: PMC5075795 DOI: 10.1038/srep35747] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/30/2016] [Indexed: 11/29/2022] Open
Abstract
Here we describe “Supernova” series of vector systems that enable single-cell labeling and labeled cell-specific gene manipulation, when introduced by in utero electroporation (IUE) or adeno-associated virus (AAV)-mediated gene delivery. In Supernova, sparse labeling relies on low TRE leakage. In a small population of cells with over-threshold leakage, initial tTA-independent weak expression is enhanced by tTA/TRE-positive feedback along with a site-specific recombination system (e.g., Cre/loxP, Flpe/FRT). Sparse and bright labeling by Supernova with little background enables the visualization of the morphological details of individual neurons in densely packed brain areas such as the cortex and hippocampus, both during development and in adulthood. Sparseness levels are adjustable. Labeled cell-specific gene knockout was accomplished by introducing Cre/loxP-based Supernova vectors into floxed mice. Furthermore, by combining with RNAi, TALEN, and CRISPR/Cas9 technologies, IUE-based Supernova achieved labeled cell-specific gene knockdown and editing/knockout without requiring genetically altered mice. Thus, Supernova system is highly extensible and widely applicable for single-cell analyses in complex organs, such as the mammalian brain.
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Affiliation(s)
- Wenshu Luo
- Division of Neurogenetics, National Institute of Genetics, Mishima, 411-8540, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Hidenobu Mizuno
- Division of Neurogenetics, National Institute of Genetics, Mishima, 411-8540, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Ryohei Iwata
- Division of Neurogenetics, National Institute of Genetics, Mishima, 411-8540, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Shingo Nakazawa
- Division of Neurogenetics, National Institute of Genetics, Mishima, 411-8540, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
| | - Kosuke Yasuda
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, 351-0198, Japan
| | - Shigeyoshi Itohara
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, 351-0198, Japan
| | - Takuji Iwasato
- Division of Neurogenetics, National Institute of Genetics, Mishima, 411-8540, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, 411-8540, Japan
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Lo FS, Erzurumlu RS. Sensory Activity-Dependent and Sensory Activity-Independent Properties of the Developing Rodent Trigeminal Principal Nucleus. Dev Neurosci 2016; 38:163-170. [PMID: 27287019 DOI: 10.1159/000446395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/24/2016] [Indexed: 11/19/2022] Open
Abstract
The whisker-sensory trigeminal central pathway of rodents is an established model for studies of activity-dependent neural plasticity. The first relay station of the pathway is the trigeminal principal nucleus (PrV), the ventral part of which receives sensory inputs mainly from the infraorbital branch of the maxillary trigeminal nerve (ION). Whisker-sensory afferents play an important role in the development of the morphological and physiological properties of PrV neurons. In neonates, deafferentation by ION transection leads to the disruption of whisker-related neural patterns (barrelettes) and cell death within a specific time window (critical period), as revealed by morphological studies. Whisker-sensory inputs control synaptic elimination, postsynaptic AMPA receptor trafficking, astrocyte-mediated synaptogenesis, and receptive-field characteristics of PrV cells, without a postnatal critical period. Sensory activity-dependent synaptic plasticity requires the activation of NMDA receptors and involves the participation of glia. However, the basic physiological properties of PrV neurons, such as cell type-specific ion channels, presynaptic terminal function, postsynaptic NMDA receptor subunit composition, and formation of the inhibitory circuitry, are independent of sensory inputs. Therefore, the first relay station of the whisker sensation is largely mature-like and functional at birth. Delineation of activity-dependent and activity-independent features of the postnatal PrV is important for understanding the development and functional characteristics of downstream trigeminal stations in the thalamus and neocortex. This mini review focuses on such features of the developing rodent PrV.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Md., USA
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30
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Lo FS, Blue ME, Erzurumlu RS. Enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses in the barrel cortex of Mecp2-null mice. J Neurophysiol 2016; 115:1298-306. [PMID: 26683074 PMCID: PMC4808090 DOI: 10.1152/jn.00944.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/15/2015] [Indexed: 12/12/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder that results from mutations in the X-linked gene for methyl-CpG-binding protein 2 (MECP2). The underlying cellular mechanism for the sensory deficits in patients with RTT is largely unknown. This study used the Bird mouse model of RTT to investigate sensory thalamocortical synaptic transmission in the barrel cortex of Mecp2-null mice. Electrophysiological results showed an excitation/inhibition imbalance, biased toward inhibition, due to an increase in efficacy of postsynaptic GABAA receptors rather than alterations in inhibitory network and presynaptic release properties. Enhanced inhibition impaired the transmission of tonic sensory signals from the thalamus to the somatosensory cortex. Previous morphological studies showed an upregulation of NMDA receptors in the neocortex of both RTT patients and Mecp2-null mice at early ages [Blue ME, Naidu S, Johnston MV. Ann Neurol 45: 541-545, 1999; Blue ME, Kaufmann WE, Bressler J, Eyring C, O'Driscoll C, Naidu S, Johnston MV. Anat Rec (Hoboken) 294: 1624-1634, 2011]. Although AMPA and NMDA receptor-mediated excitatory synaptic transmission was not altered in the barrel cortex of Mecp2-null mice, extrasynaptic NMDA receptor-mediated responses increased markedly. These responses were blocked by memantine, suggesting that extrasynaptic NMDA receptors play an important role in the pathogenesis of RTT. The results suggest that enhancement of postsynaptic GABAA and extrasynaptic NMDA receptor-mediated responses may underlie impaired somatosensation and that pharmacological blockade of extrasynaptic NMDA receptors may have therapeutic value for RTT.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Mary E Blue
- Hugo W. Moser Research Institute at Kennedy Krieger, Inc. and Departments of Neurology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland; and
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31
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Developmental RacGAP α2-Chimaerin Signaling Is a Determinant of the Morphological Features of Dendritic Spines in Adulthood. J Neurosci 2016; 35:13728-44. [PMID: 26446225 DOI: 10.1523/jneurosci.0419-15.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Morphological characteristics of dendritic spines form the basis of cognitive ability. However, molecular mechanisms involved in fine-tuning of spine morphology during development are not fully understood. Moreover, it is unclear whether, and to what extent, these developmental mechanisms determine the normal adult spine morphological features. Here, we provide evidence that α2-isoform of Rac-specific GTPase-activating protein α-chimaerin (α2-chimaerin) is involved in spine morphological refinement during late postnatal period, and furthermore show that this developmental α2-chimaerin function affects adult spine morphologies. We used a series of mice with global and conditional knock-out of α-chimaerin isoforms (α1-chimaerin and α2-chimaerin). α2-Chimaerin disruption, but not α1-chimaerin disruption, in the mouse results in an increased size (and density) of spines in the hippocampus. In contrast, overexpression of α2-chimaerin in developing hippocampal neurons induces a decrease of spine size. Disruption of α2-chimaerin suppressed EphA-mediated spine morphogenesis in cultured developing hippocampal neurons. α2-Chimaerin disruption that begins during the juvenile stage results in an increased size of spines in the hippocampus. Meanwhile, spine morphologies are unaltered when α2-chimaerin is deleted only in adulthood. Consistent with these spine morphological results, disruption of α2-chimaerin beginning in the juvenile stage led to an increase in contextual fear learning in adulthood; whereas contextual learning was recently shown to be unaffected when α2-chimaerin was deleted only in adulthood. Together, these results suggest that α2-chimaerin signaling in developmental stages contributes to determination of the morphological features of adult spines and establishment of normal cognitive ability. SIGNIFICANCE STATEMENT Recent studies of neurodevelopmental disorders in humans and their animal models have led to an attractive hypothesis that spine morphogenesis during development forms the basis of adult cognition. In particular, the roles of Rac and its regulators, such as Rac-specific GTPase-activating proteins (RacGAPs) and Rac guanine nucleotide exchange factors, are a topic of focus in spine morphogenesis and cognitive ability. Using a series of mice with global and conditional knock-out (KO) of RacGAP α-chimaerin isoforms (α1-chimaerin and α2-chimaerin), we provide compelling evidence demonstrating that α2-chimaerin is involved in spine morphological refinement during late postnatal development and that this developmental α2-chimaerin function affects adult spine morphologies. Furthermore, our results clearly showed that α2-chimaerin signaling during late postnatal development contributes to normal cognitive ability in adult mice.
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32
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Lo FS, Erzurumlu RS. Neonatal sensory nerve injury-induced synaptic plasticity in the trigeminal principal sensory nucleus. Exp Neurol 2016; 275 Pt 2:245-52. [PMID: 25956829 PMCID: PMC4636484 DOI: 10.1016/j.expneurol.2015.04.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 04/29/2015] [Indexed: 11/26/2022]
Abstract
Sensory deprivation studies in neonatal mammals, such as monocular eye closure, whisker trimming, and chemical blockade of the olfactory epithelium have revealed the importance of sensory inputs in brain wiring during distinct critical periods. But very few studies have paid attention to the effects of neonatal peripheral sensory nerve damage on synaptic wiring of the central nervous system (CNS) circuits. Peripheral somatosensory nerves differ from other special sensory afferents in that they are more prone to crush or severance because of their locations in the body. Unlike the visual and auditory afferents, these nerves show regenerative capabilities after damage. Uniquely, damage to a somatosensory peripheral nerve does not only block activity incoming from the sensory receptors but also mediates injury-induced neuro- and glial chemical signals to the brain through the uninjured central axons of the primary sensory neurons. These chemical signals can have both far more and longer lasting effects than sensory blockade alone. Here we review studies which focus on the consequences of neonatal peripheral sensory nerve damage in the principal sensory nucleus of the brainstem trigeminal complex.
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Affiliation(s)
- Fu-Sun Lo
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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33
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Glutamate input in the dorsal raphe nucleus as a determinant of escalated aggression in male mice. J Neurosci 2015; 35:6452-63. [PMID: 25904796 DOI: 10.1523/jneurosci.2450-14.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although the dorsal raphe nucleus (DRN) has long been linked to neural control of aggression, little is known about the regulatory influences of the DRN when an animal engages in either adaptive species-typical aggressive behavior or escalated aggression. Therefore it is important to explore which neurotransmitter inputs into the DRN determine the escalation of aggression in male mice. Previously, we observed that microinjection of the GABAB receptor agonist baclofen into the DRN escalates aggressive behavior in male mice. Here, we used a serotonin (5-HT) neuron-specific GABAB receptor knock-out mouse to demonstrate that baclofen acts on nonserotonergic neurons to escalate aggression. Intra-DRN baclofen administration increased glutamate release, but did not alter GABA release, within the DRN. Microinjection of l-glutamate into the DRN escalated dose-dependently attack bites toward an intruder. In vivo microdialysis showed that glutamate release increased in the DRN during an aggressive encounter, and the level of glutamate was further increased when the animal was engaged in escalated aggressive behavior after social instigation. Finally, 5-HT release was increased within the DRN and also in the medial prefrontal cortex when animals were provoked by social instigation, and during escalated aggression after social instigation, but this increase in 5-HT release was not observed when animals were engaged in species-typical aggression. In summary, glutamate input into the DRN is enhanced during escalated aggression, which causes a phasic increase of 5-HT release from the DRN 5-HT neurons.
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Suzuki A, Lee LJ, Hayashi Y, Muglia L, Itohara S, Erzurumlu RS, Iwasato T. Thalamic adenylyl cyclase 1 is required for barrel formation in the somatosensory cortex. Neuroscience 2015; 290:518-29. [PMID: 25644422 DOI: 10.1016/j.neuroscience.2015.01.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/21/2014] [Accepted: 01/06/2015] [Indexed: 12/22/2022]
Abstract
Cyclic AMP signaling is critical for activity-dependent refinement of neuronal circuits. Global disruption of adenylyl cyclase 1 (AC1), the major calcium/calmodulin-stimulated adenylyl cyclase in the brain, impairs formation of whisker-related discrete neural modules (the barrels) in cortical layer 4 in mice. Since AC1 is expressed both in the thalamus and the neocortex, the question of whether pre- or postsynaptic (or both) AC1 plays a role in barrel formation has emerged. Previously, we generated cortex-specific AC1 knockout (Cx-AC1KO) mice and found that these animals develop histologically normal barrels, suggesting a potentially more prominent role for thalamic AC1 in barrel formation. To determine this, we generated three new lines of mice: one in which AC1 is disrupted in nearly half of the thalamic ventrobasal nucleus cells in addition to the cortical excitatory neurons (Cx/pTh-AC1KO mouse), and another in which AC1 is disrupted in the thalamus but not in the cortex or brainstem nuclei of the somatosensory system (Th-AC1KO mouse). Cx/pTh-AC1KO mice show severe deficits in barrel formation. Th-AC1KO mice show even more severe disruption in barrel patterning. In these two lines, single thalamocortical (TC) axon labeling revealed a larger lateral extent of TC axons in layer 4 compared to controls. In the third line, all calcium-stimulated adenylyl cyclases (both AC1 and AC8) are deleted in cortical excitatory neurons. These mice have normal barrels. Taken together, these results indicate that thalamic AC1 plays a major role in patterning and refinement of the mouse TC circuitry.
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Affiliation(s)
- A Suzuki
- Division of Neurogenetics, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan
| | - L-J Lee
- Department of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
| | - Y Hayashi
- Laboratory for Behavioral Genetics, RIKEN Brain Science (BSI) Institute, Wako, Saitama 351-0198, Japan
| | - L Muglia
- Perinatal Institute, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - S Itohara
- Laboratory for Behavioral Genetics, RIKEN Brain Science (BSI) Institute, Wako, Saitama 351-0198, Japan
| | - R S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, MD 21201-1075, USA
| | - T Iwasato
- Division of Neurogenetics, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan; Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan.
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Arakawa H, Akkentli F, Erzurumlu RS. Region-Specific Disruption of Adenylate Cyclase Type 1 Gene Differentially Affects Somatosensorimotor Behaviors in Mice. eNeuro 2014; 1:http://dx.doi.org/10.1523/ENEURO.0007-14.2014. [PMID: 26023682 PMCID: PMC4443438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Adenylate cyclase type I (AC1) is primarily, and, abundantly, expressed in the brain. Intracellular calcium/ calmodulin increases regulate AC1 in an activity-dependent manner. Upon stimulation, AC1 produces cAMP and it is involved in the patterning and the refinement of neural circuits. In mice, spontaneous mutations or targeted deletion of the Adcy1 gene, which encodes AC1, resulted in neuronal pattern formation defects. Neural modules in the primary somatosensory (SI) cortex, the barrels, which represent the topographic distribution of the whiskers on the snout, failed to form (Welker et al., 1996; Abdel-Majid et al., 1998). Cortex- or thalamus-specific Adcy1 deletions led to different cortical pattern phenotypes, with thalamus-specific disruption phenotype being more severe (Iwasato et al., 2008; Suzuki et al., 2013). Despite the absence of barrels in the "barrelless"/Adcy1 null mice, thalamocortical terminal bouton density and activation of cortical zones following whisker stimulation were roughly topographic (Abdel-Majid et al., 1998; Gheorghita et al., 2006). To what extent does patterning of the cortical somatosensory body map play a role in sensorimotor behaviors? In this study, we tested mice with global, cortical, or thalamic loss of AC1 function in a battery of sensorimotor and social behavior tests and compared them to mice with all of the whiskers clipped. Contrary to intuitive expectations that any region-specific or global disruption of the AC1 function would lead to similar behavioral phenotypes, we found significant differences in the degree of impairment between these strains.
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Averaimo S, Nicol X. Intermingled cAMP, cGMP and calcium spatiotemporal dynamics in developing neuronal circuits. Front Cell Neurosci 2014; 8:376. [PMID: 25431549 PMCID: PMC4230202 DOI: 10.3389/fncel.2014.00376] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/21/2014] [Indexed: 01/27/2023] Open
Abstract
cAMP critically modulates the development of neuronal connectivity. It is involved in a wide range of cellular processes that require independent regulation. However, our understanding of how this single second messenger achieves specific modulation of the signaling pathways involved remains incomplete. The subcellular compartmentalization and temporal regulation of cAMP signals have recently been identified as important coding strategies leading to specificity. Dynamic interactions of this cyclic nucleotide with other second messenger including calcium and cGMP are critically involved in the regulation of spatiotemporal control of cAMP. Recent technical improvements of fluorescent sensors facilitate cAMP monitoring, whereas optogenetic tools permit spatial and temporal control of cAMP manipulations, all of which enabled the direct investigation of spatiotemporal characteristics of cAMP modulation in developing neurons. Focusing on neuronal polarization, neurotransmitter specification, axon guidance, and refinement of neuronal connectivity, we summarize herein the recent advances in understanding the features of cAMP signals and their dynamic interactions with calcium and cGMP involved in shaping the nervous system.
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Affiliation(s)
- Stefania Averaimo
- UMR_7210, Centre National de la Recherche Scientifique Paris, France ; UMR_S 968, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06 Paris, France ; U968, Institut National de la Santé et de la Recherche Médicale Paris, France
| | - Xavier Nicol
- UMR_7210, Centre National de la Recherche Scientifique Paris, France ; UMR_S 968, Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06 Paris, France ; U968, Institut National de la Santé et de la Recherche Médicale Paris, France
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37
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Region-Specific Disruption of Adenylate Cyclase Type 1 Gene Differentially Affects Somatosensorimotor Behaviors in Mice(1,2,3). eNeuro 2014; 1:eN-NWR-0007-14. [PMID: 26464960 PMCID: PMC4596139 DOI: 10.1523/eneuro.0007-14.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/24/2014] [Accepted: 10/24/2014] [Indexed: 02/04/2023] Open
Abstract
The neuron-specific calcium-stimulated adenylate cyclase 1 (AC1) is important for refinement of topographic maps in the brain. AC1 is expressed at all levels of the somatosensory pathway and global or region-specific gene deletions lead to differential pattern phenotypes. Region-specific adenylyl cyclase 1 (AC1) loss of function differentially affects both patterning and sensorimotor behaviors in mice. AC1 is expressed at all levels of the somatosensory pathway and plays a major role in refinement and patterning of topographic sensory maps. Cortex-specific AC1 loss of function (CxAC1KO mice) does not affect barrel patterning and activation of specific barrels corresponding to stimulated whiskers and does not impair sensorimotor behaviors. While global (AC1KO) and thalamus-specific (ThAC1KO) AC1 loss of function leads to absence of barrel patterns, selective whisker stimulation activates topographically aligned cortical loci. Despite functional topography of the whisker-barrel cortex, sensorimotor and social behaviors are impaired, indicating the importance of patterning of topographical sensory maps in the neocortex. ![]()
Adenylate cyclase type I (AC1) is primarily, and, abundantly, expressed in the brain. Intracellular calcium/calmodulin increases regulate AC1 in an activity-dependent manner. Upon stimulation, AC1 produces cAMP and it is involved in the patterning and the refinement of neural circuits. In mice, spontaneous mutations or targeted deletion of the Adcy1 gene, which encodes AC1, resulted in neuronal pattern formation defects. Neural modules in the primary somatosensory (SI) cortex, the barrels, which represent the topographic distribution of the whiskers on the snout, failed to form (Welker et al., 1996; Abdel-Majid et al., 1998). Cortex- or thalamus-specific Adcy1 deletions led to different cortical pattern phenotypes, with thalamus-specific disruption phenotype being more severe (Iwasato et al., 2008; Suzuki et al., 2013). Despite the absence of barrels in the “barrelless”/Adcy1 null mice, thalamocortical terminal bouton density and activation of cortical zones following whisker stimulation were roughly topographic (Abdel-Majid et al., 1998; Gheorghita et al., 2006). To what extent does patterning of the cortical somatosensory body map play a role in sensorimotor behaviors? In this study, we tested mice with global, cortical, or thalamic loss of AC1 function in a battery of sensorimotor and social behavior tests and compared them to mice with all of the whiskers clipped. Contrary to intuitive expectations that any region-specific or global disruption of the AC1 function would lead to similar behavioral phenotypes, we found significant differences in the degree of impairment between these strains.
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Iwata R, Ohi K, Kobayashi Y, Masuda A, Iwama M, Yasuda Y, Yamamori H, Tanaka M, Hashimoto R, Itohara S, Iwasato T. RacGAP α2-Chimaerin Function in Development Adjusts Cognitive Ability in Adulthood. Cell Rep 2014; 8:1257-64. [DOI: 10.1016/j.celrep.2014.07.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 06/20/2014] [Accepted: 07/25/2014] [Indexed: 11/24/2022] Open
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Vitali I, Jabaudon D. Synaptic biology of barrel cortex circuit assembly. Semin Cell Dev Biol 2014; 35:156-64. [PMID: 25080022 DOI: 10.1016/j.semcdb.2014.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/10/2014] [Accepted: 07/17/2014] [Indexed: 02/04/2023]
Abstract
Mature neuronal circuits arise from the coordinated interplay of cell-intrinsic differentiation programs, target-derived signals and activity-dependent processes. Typically, cell-intrinsic mechanisms predominate at early stages of differentiation, while input-dependent processes modulate circuit formation at later stages of development. The whisker barrel cortex of rodents is particularly well suited to study this latter phase. During the first few days after birth, thalamocortical axons (TCA) from the somatosensory ventral posteromedial nucleus (VPM) form synapses onto layer 4 (L4) neurons, which aggregate to form barrels, whose spatial organization corresponds to the distribution of the whiskers on the snout. Besides specific genetic programs, which control TCA and L4 neuron specification, the establishment of the barrel pattern also depends on the information resulting from whisker activation. The plasticity of this system during the first few days after birth is critical for barrel formation: damage to the sensory periphery impairs TCA patterning, while lesions after this period have less pronounced effects. Here, we will review the role and position of L4 neurons within cortical columnar circuits and synaptogenesis during barrel formation.
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Affiliation(s)
- Ilaria Vitali
- Department of Basic Neurosciences, University of Geneva, Switzerland
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva, Switzerland.
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Lokmane L, Garel S. Map transfer from the thalamus to the neocortex: inputs from the barrel field. Semin Cell Dev Biol 2014; 35:147-55. [PMID: 25020201 DOI: 10.1016/j.semcdb.2014.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 01/05/2023]
Abstract
Sensory perception relies on the formation of stereotyped maps inside the brain. This feature is particularly well illustrated in the mammalian neocortex, which is subdivided into distinct cortical sensory areas that comprise topological maps, such as the somatosensory homunculus in humans or the barrel field of the large whiskers in rodents. How somatosensory maps are formed and relayed into the neocortex remain essential questions in developmental neuroscience. Here, we will present our current knowledge on whisker map transfer in the mouse model, with the goal of linking embryonic and postnatal studies into a comprehensive framework.
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Affiliation(s)
- Ludmilla Lokmane
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, 46 rue d'Ulm, Paris F-75005, France; Inserm, U1024, Paris F-75005, France; CNRS, UMR 8197, Paris F-75005, France.
| | - Sonia Garel
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, 46 rue d'Ulm, Paris F-75005, France; Inserm, U1024, Paris F-75005, France; CNRS, UMR 8197, Paris F-75005, France.
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Spinal glutamatergic neurons defined by EphA4 signaling are essential components of normal locomotor circuits. J Neurosci 2014; 34:3841-53. [PMID: 24623763 DOI: 10.1523/jneurosci.4992-13.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
EphA4 signaling is essential for the spatiotemporal organization of neuronal circuit formation. In mice, deletion of this signaling pathway causes aberrant midline crossing of axons from both brain and spinal neurons and the complete knock-outs (KOs) exhibit a pronounced change in motor behavior, where alternating gaits are replaced by a rabbit-like hopping gait. The neuronal mechanism that is responsible for the gait switch in these KO mice is not known. Here, using intersectional genetics, we demonstrate that a spinal cord-specific deletion of EphA4 signaling is sufficient to generate the overground hopping gait. In contrast, selective deletion of EphA4 signaling in forebrain neurons, including the corticospinal tract neurons, did not result in a change in locomotor pattern. The gait switch was attributed to the loss of EphA4 signaling in excitatory Vglut2+ neurons, which is accompanied by an increased midline crossing of Vglut2+ neurons in the ventral spinal cord. Our findings functionally define spinal EphA4 signaling in excitatory Vglut2+ neurons as required for proper organization of the spinal locomotor circuitry, and place these cells as essential components of the mammalian locomotor network.
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Mizuno H, Luo W, Tarusawa E, Saito Y, Sato T, Yoshimura Y, Itohara S, Iwasato T. NMDAR-Regulated Dynamics of Layer 4 Neuronal Dendrites during Thalamocortical Reorganization in Neonates. Neuron 2014; 82:365-79. [DOI: 10.1016/j.neuron.2014.02.026] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2014] [Indexed: 11/29/2022]
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Nicol X, Gaspar P. Routes to cAMP: shaping neuronal connectivity with distinct adenylate cyclases. Eur J Neurosci 2014; 39:1742-51. [PMID: 24628976 DOI: 10.1111/ejn.12543] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/03/2014] [Accepted: 02/04/2014] [Indexed: 01/22/2023]
Abstract
cAMP signaling affects a large number of the developmental processes needed for the construction of the CNS, including cell differentiation, axon outgrowth, response to guidance molecules or modulation of synaptic connections. This points to a key role of adenylate cyclases (ACs), the synthetic enzymes of cAMP, for neural development. ACs exist as 10 different isoforms, which are activated by distinct signaling pathways. The implication of specific AC isoforms in neural wiring was only recently demonstrated in mouse mutants, knockout (KO) for different AC isoforms, AC1, AC3, AC5, AC8 and soluble (s)AC/AC10. These studies stressed the importance of three of these isoforms, as sensors of neural activity that could modify the survival of neurons (sAC), axon outgrowth (sAC), or the response of axons to guidance molecules such as ephrins (AC1) or semaphorins (AC3). We summarize here the current knowledge on the role of these ACs for the development of sensory maps, in the somatosensory, visual and olfactory systems, which have been the most extensively studied. In these systems, AC1/AC3 KO revealed targeting mistakes due to the defective pruning and lack of discrimination of incoming axons to signals present in target structures. In contrast, no changes in cell differentiation, survival or axon outgrowth were noted in these mutants, suggesting a specificity of cAMP production routes for individual cellular processes within a given neuron. Further studies indicate that the subcellular localization of ACs could be key to their specific role in axon targeting and may explain their selective roles in neuronal wiring.
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Affiliation(s)
- Xavier Nicol
- Inserm UMR-S 968, Institut de la Vision, 75012, Paris, France; CNRS UMR 7210, 75012, Paris, France; Université Pierre et Marie Curie, Paris, France
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Laminar and columnar development of barrel cortex relies on thalamocortical neurotransmission. Neuron 2013; 79:970-86. [PMID: 24012009 DOI: 10.1016/j.neuron.2013.06.043] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2013] [Indexed: 12/21/2022]
Abstract
A dynamic interplay between intrinsic regional molecular cues and extrinsic factors from the thalamus shape multiple features of early cortical development. It remains uncertain and controversial, however, whether the initial formation of cortical columns depends on neuronal activity, and there is little evidence that cortical lamination or neuronal differentiation is influenced by extrinsic activity. We examined the role of thalamic-derived factors in cortical development by selectively eliminating glutamatergic synaptic transmission from thalamocortical neurons in mice and found that eliminating thalamocortical neurotransmission prevented the formation of "barrel" columns in somatosensory cortex. Interestingly, based on cytoarchitectonic criteria and genetic markers, blocking thalamocortical neurotransmission also perturbed the development of superficial cortical lamina and the morphologic development of neurons. These experiments demonstrate that barrels and aspects of the layer-dependent pattern of cortical cytoarchitecture, gene expression, and neuronal differentiation depend on thalamocortical neurotransmission, extending the apparent influence of extrinsic, presumably activity-dependent factors, on cortical development.
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Platel JC, Kelsch W. Role of NMDA receptors in adult neurogenesis: an ontogenetic (re)view on activity-dependent development. Cell Mol Life Sci 2013; 70:3591-601. [PMID: 23397131 PMCID: PMC11113726 DOI: 10.1007/s00018-013-1262-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 12/18/2012] [Accepted: 01/03/2013] [Indexed: 12/27/2022]
Abstract
It is now widely accepted that neurogenesis continues throughout life. Accumulating evidence suggests that neurotransmitters are essential signaling molecules that control the different steps of neurogenesis. Nevertheless, we are only beginning to understand the precise role of neurotransmitter receptors and in particular excitatory glutamatergic transmission in the differentiation of adult-born neurons. Recent technical advances allow single-cell gene deletion to study cell-autonomous effects during the maturation of adult-born neurons. Single-cell gene deletion overcomes some of the difficulties in interpreting global gene deletion effects on entire brain areas or systemic pharmacological approaches that might result in compensatory circuit effects. The aim of this review is to summarize recent advances in the understanding of the role of NMDA receptors (NMDARs) during the differentiation of adult-born neurons and put them in perspective with previous findings on cortical development.
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Affiliation(s)
- Jean-Claude Platel
- Grenoble Institut des Neurosciences U836, Université Joseph Fourier, Site Santé La Tronche BP 170, 38042 Grenoble Cedex 9, France
| | - Wolfgang Kelsch
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5, 68159 Mannheim, Germany
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Ogiwara I, Iwasato T, Miyamoto H, Iwata R, Yamagata T, Mazaki E, Yanagawa Y, Tamamaki N, Hensch TK, Itohara S, Yamakawa K. Nav1.1 haploinsufficiency in excitatory neurons ameliorates seizure-associated sudden death in a mouse model of Dravet syndrome. Hum Mol Genet 2013; 22:4784-804. [PMID: 23922229 PMCID: PMC3820136 DOI: 10.1093/hmg/ddt331] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Dravet syndrome is a severe epileptic encephalopathy mainly caused by heterozygous mutations in the SCN1A gene encoding a voltage-gated sodium channel Nav1.1. We previously reported dense localization of Nav1.1 in parvalbumin (PV)-positive inhibitory interneurons in mice and abnormal firing of those neurons in Nav1.1-deficient mice. In the present study, we investigated the physiologic consequence of selective Nav1.1 deletion in mouse global inhibitory neurons, forebrain excitatory neurons or PV cells, using vesicular GABA transporter (VGAT)-Cre, empty spiracles homolog 1 (Emx1)-Cre or PV-Cre recombinase drivers. We show that selective Nav1.1 deletion using VGAT-Cre causes epileptic seizures and premature death that are unexpectedly more severe than those observed in constitutive Nav1.1-deficient mice. Nav1.1 deletion using Emx1-Cre does not cause any noticeable abnormalities in mice; however, the severe lethality observed with VGAT-Cre-driven Nav1.1 deletion is rescued by additional Nav1.1 deletion using Emx1-Cre. In addition to predominant expression in PV interneurons, we detected Nav1.1 in subpopulations of excitatory neurons, including entorhino-hippocampal projection neurons, a subpopulation of neocortical layer V excitatory neurons, and thalamo-cortical projection neurons. We further show that even minimal selective Nav1.1 deletion, using PV-Cre, is sufficient to cause spontaneous epileptic seizures and ataxia in mice. Overall, our results indicate that functional impairment of PV inhibitory neurons with Nav1.1 haploinsufficiency contributes to the epileptic pathology of Dravet syndrome, and show for the first time that Nav1.1 haploinsufficiency in excitatory neurons has an ameliorating effect on the pathology.
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Affiliation(s)
- Ikuo Ogiwara
- Laboratory for NeurogeneticsRIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Abstract
In primary sensory neocortical areas of mammals, the distribution of sensory receptors is mapped with topographic precision and amplification in proportion to the peripheral receptor density. The visual, somatosensory and auditory cortical maps are established during a critical period in development. Throughout this window in time, the developing cortical maps are vulnerable to deleterious effects of sense organ damage or sensory deprivation. The rodent barrel cortex offers an invaluable model system with which to investigate the mechanisms underlying the formation of topographic maps and their plasticity during development. Five rows of mystacial vibrissa (whisker) follicles on the snout and an array of sinus hairs are represented by layer IV neural modules ('barrels') and thalamocortical axon terminals in the primary somatosensory cortex. Perinatal damage to the whiskers or the sensory nerve innervating them irreversibly alters the structural organization of the barrels. Earlier studies emphasized the role of the sensory periphery in dictating whisker-specific brain maps and patterns. Recent advances in molecular genetics and analyses of genetically altered mice allow new insights into neural pattern formation in the neocortex and the mechanisms underlying critical period plasticity. Here, we review the development and patterning of the barrel cortex and the critical period plasticity.
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Affiliation(s)
- Reha S Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201-1075, USA.
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Dhande OS, Bhatt S, Anishchenko A, Elstrott J, Iwasato T, Swindell EC, Xu HP, Jamrich M, Itohara S, Feller MB, Crair MC. Role of adenylate cyclase 1 in retinofugal map development. J Comp Neurol 2012; 520:1562-83. [PMID: 22102330 DOI: 10.1002/cne.23000] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The development of topographic maps of the sensory periphery is sensitive to the disruption of adenylate cyclase 1 (AC1) signaling. AC1 catalyzes the production of cAMP in a Ca2+/calmodulin-dependent manner, and AC1 mutant mice (AC1−/−) have disordered visual and somatotopic maps. However, the broad expression of AC1 in the brain and the promiscuous nature of cAMP signaling have frustrated attempts to determine the underlying mechanism of AC1-dependent map development. In the mammalian visual system, the initial coarse targeting of retinal ganglion cell (RGC) projections to the superior colliculus (SC) and lateral geniculate nucleus (LGN) is guided by molecular cues, and the subsequent refinement of these crude projections occurs via an activity-dependent process that depends on spontaneous retinal waves. Here, we show that AC1−/− mice have normal retinal waves but disrupted map refinement. We demonstrate that AC1 is required for the emergence of dense and focused termination zones and elimination of inaccurately targeted collaterals at the level of individual retinofugal arbors. Conditional deletion of AC1 in the retina recapitulates map defects, indicating that the locus of map disruptions in the SC and dorsal LGN of AC1−/− mice is presynaptic. Finally, map defects in mice without AC1 and disrupted retinal waves (AC1−/−;β2−/− double KO mice) are no worse than those in mice lacking only β2−/−, but loss of AC1 occludes map recovery in β2−/− mice during the second postnatal week. These results suggest that AC1 in RGC axons mediates the development of retinotopy and eye-specific segregation in the SC and dorsal LGN.
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Affiliation(s)
- Onkar S Dhande
- Department of Neurobiology, Yale University, New Haven, Connecticut 06510, USA
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Hirayama T, Tarusawa E, Yoshimura Y, Galjart N, Yagi T. CTCF is required for neural development and stochastic expression of clustered Pcdh genes in neurons. Cell Rep 2012; 2:345-57. [PMID: 22854024 DOI: 10.1016/j.celrep.2012.06.014] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 06/13/2012] [Accepted: 06/15/2012] [Indexed: 12/17/2022] Open
Abstract
The CCCTC-binding factor (CTCF) is a key molecule for chromatin conformational changes that promote cellular diversity, but nothing is known about its role in neurons. Here, we produced mice with a conditional knockout (cKO) of CTCF in postmitotic projection neurons, mostly in the dorsal telencephalon. The CTCF-cKO mice exhibited postnatal growth retardation and abnormal behavior and had defects in functional somatosensory mapping in the brain. In terms of gene expression, 390 transcripts were expressed at significantly different levels between CTCF-deficient and control cortex and hippocampus. In particular, the levels of 53 isoforms of the clustered protocadherin (Pcdh) genes, which are stochastically expressed in each neuron, declined markedly. Each CTCF-deficient neuron showed defects in dendritic arborization and spine density during brain development. Their excitatory postsynaptic currents showed normal amplitude but occurred with low frequency. Our results indicate that CTCF regulates functional neural development and neuronal diversity by controlling clustered Pcdh expression.
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Affiliation(s)
- Teruyoshi Hirayama
- KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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50
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Zaccaria KJ, McCasland JS. Emergence of layer IV barrel cytoarchitecture is delayed in somatosensory cortex of GAP-43 deficient mice following delayed development of dendritic asymmetry. Somatosens Mot Res 2012; 29:77-88. [PMID: 22759196 DOI: 10.3109/08990220.2012.686936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The emergence of barrel cytoarchitecture in mouse somatosensory cortex is extremely well defined. However, mechanisms underlying the development of this cellular organization are not completely understood. While it is generally accepted that hollows emerge via passive displacement of cortical cells by dense thalamocortical afferent clusters in barrel centers, it is not known what causes cellular segregation of barrel sides and septa. Here, we hypothesized that the emergence of sides and septa is related to the progressive asymmetry of dendrites from the cells of the barrel side toward the barrel hollow during development. We tested this hypothesis in the barrel cortex of growth-associated protein-43 heterozygous mice (GAP43 (+/-) mice) that display a 2-day delay in retraction of septally oriented dendrites compared to (+/+) littermates. We predicted that this delayed retraction would result in a subsequent 2-day delay in the emergence of barrel sides and septa. Using cresyl violet staining of barrel cortex, we found that initial emergence of hollows was not different between GAP43 (+/-) mice and (+/+) littermate controls. However, the emergence of sides and septa was delayed by 2 days, supporting our hypothesis that the emergence of barrel sides and septa is related to, and perhaps reliant upon, the developmental step of dendritic orientation toward barrel hollows. This process, which is mechanistically distinct from the emergence of barrel hollows, is likely due to both active and passive events resulting from asymmetric cell orientation.
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Affiliation(s)
- Kimberly J Zaccaria
- Department of Cell & Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, USA.
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