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Coronin 2B Regulates Neuronal Migration via Rac1-Dependent Multipolar-Bipolar Transition. J Neurosci 2023; 43:211-220. [PMID: 36639906 PMCID: PMC9838710 DOI: 10.1523/jneurosci.1087-22.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 10/24/2022] [Accepted: 11/19/2022] [Indexed: 12/12/2022] Open
Abstract
In the developing cortex, excitatory neurons migrate along the radial fibers to their final destinations and build up synaptic connection with each other to form functional circuitry. The shaping of neuronal morphologies by actin cytoskeleton dynamics is crucial for neuronal migration. However, it is largely unknown how the distribution and assembly of the F-actin cytoskeleton are coordinated. In the present study, we found that an actin regulatory protein, coronin 2B, is indispensable for the transition from a multipolar to bipolar morphology during neuronal migration in ICR mice of either sex. Loss of coronin 2B led to heterotopic accumulation of migrating neurons in the intermediate zone along with reduced dendritic complexity and aberrant neuronal activity in the cortical plate. This was accompanied by increased seizure susceptibility, suggesting the malfunction of cortical development in coronin 2B-deficient brains. Coronin 2B knockdown disrupted the distribution of the F-actin cytoskeleton at the leading processes, while the migration defect in coronin 2B-deficient neurons was partially rescued by overexpression of Rac1 and its downstream actin-severing protein, cofilin. Our results collectively reveal the physiological function of coronin 2B during neuronal migration whereby it maintains the proper distribution of activated Rac1 and the F-actin cytoskeleton.SIGNIFICANCE STATEMENT Deficits in neuronal migration during cortical development result in various neurodevelopmental disorders (e.g., focal cortical dysplasia, periventricular heterotopia, epilepsy, etc.). Most signaling pathways that control neuronal migration process converge to regulate actin cytoskeleton dynamics. Therefore, it is important to understand how actin dynamics is coordinated in the critical processes of neuronal migration. Herein, we report that coronin 2B is a key protein that regulates neuronal migration through its ability to control the distribution of the actin cytoskeleton and its regulatory signaling protein Rac1 during the multipolar-bipolar transition in the intermediate zone, providing insights into the molecular machinery that drives the migration process of newborn neurons.
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Lee WS, Baldassari S, Stephenson SEM, Lockhart PJ, Baulac S, Leventer RJ. Cortical Dysplasia and the mTOR Pathway: How the Study of Human Brain Tissue Has Led to Insights into Epileptogenesis. Int J Mol Sci 2022; 23:1344. [PMID: 35163267 PMCID: PMC8835853 DOI: 10.3390/ijms23031344] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 02/01/2023] Open
Abstract
Type II focal cortical dysplasia (FCD) is a neuropathological entity characterised by cortical dyslamination with the presence of dysmorphic neurons only (FCDIIA) or the presence of both dysmorphic neurons and balloon cells (FCDIIB). The year 2021 marks the 50th anniversary of the recognition of FCD as a cause of drug resistant epilepsy, and it is now the most common reason for epilepsy surgery. The causes of FCD remained unknown until relatively recently. The study of resected human FCD tissue using novel genomic technologies has led to remarkable advances in understanding the genetic basis of FCD. Mechanistic parallels have emerged between these non-neoplastic lesions and neoplastic disorders of cell growth and differentiation, especially through perturbations of the mammalian target of rapamycin (mTOR) signalling pathway. This narrative review presents the advances through which the aetiology of FCDII has been elucidated in chronological order, from recognition of an association between FCD and the mTOR pathway to the identification of somatic mosaicism within FCD tissue. We discuss the role of a two-hit mechanism, highlight current challenges and future directions in detecting somatic mosaicism in brain and discuss how knowledge of FCD may inform novel precision treatments of these focal epileptogenic malformations of human cortical development.
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Affiliation(s)
- Wei Shern Lee
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Sara Baldassari
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013 Paris, France;
| | - Sarah E. M. Stephenson
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Paul J. Lockhart
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville 3052, Australia; (W.S.L.); (S.E.M.S.); (P.J.L.)
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
| | - Stéphanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013 Paris, France;
| | - Richard J. Leventer
- Department of Paediatrics, The University of Melbourne, Parkville 3052, Australia
- Murdoch Children’s Research Institute, Parkville 3052, Australia
- Department of Neurology, The Royal Children’s Hospital, Parkville 3052, Australia
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3
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Fernández V, Llinares-Benadero C, Borrell V. Cerebral cortex expansion and folding: what have we learned? EMBO J 2016; 35:1021-44. [PMID: 27056680 PMCID: PMC4868950 DOI: 10.15252/embj.201593701] [Citation(s) in RCA: 227] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/23/2016] [Accepted: 03/17/2016] [Indexed: 01/22/2023] Open
Abstract
One of the most prominent features of the human brain is the fabulous size of the cerebral cortex and its intricate folding. Cortical folding takes place during embryonic development and is important to optimize the functional organization and wiring of the brain, as well as to allow fitting a large cortex in a limited cranial volume. Pathological alterations in size or folding of the human cortex lead to severe intellectual disability and intractable epilepsy. Hence, cortical expansion and folding are viewed as key processes in mammalian brain development and evolution, ultimately leading to increased intellectual performance and, eventually, to the emergence of human cognition. Here, we provide an overview and discuss some of the most significant advances in our understanding of cortical expansion and folding over the last decades. These include discoveries in multiple and diverse disciplines, from cellular and molecular mechanisms regulating cortical development and neurogenesis, genetic mechanisms defining the patterns of cortical folds, the biomechanics of cortical growth and buckling, lessons from human disease, and how genetic evolution steered cortical size and folding during mammalian evolution.
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Affiliation(s)
- Virginia Fernández
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain
| | - Cristina Llinares-Benadero
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain
| | - Víctor Borrell
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan d'Alacant, Spain
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4
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Xu HT, Han Z, Gao P, He S, Li Z, Shi W, Kodish O, Shao W, Brown KN, Huang K, Shi SH. Distinct lineage-dependent structural and functional organization of the hippocampus. Cell 2014; 157:1552-64. [PMID: 24949968 DOI: 10.1016/j.cell.2014.03.067] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 02/21/2014] [Accepted: 03/29/2014] [Indexed: 12/21/2022]
Abstract
The hippocampus, as part of the cerebral cortex, is essential for memory formation and spatial navigation. Although it has been extensively studied, especially as a model system for neurophysiology, the cellular processes involved in constructing and organizing the hippocampus remain largely unclear. Here, we show that clonally related excitatory neurons in the developing hippocampus are progressively organized into discrete horizontal, but not vertical, clusters in the stratum pyramidale, as revealed by both cell-type-specific retroviral labeling and mosaic analysis with double markers (MADM). Moreover, distinct from those in the neocortex, sister excitatory neurons in the cornu ammonis 1 region of the hippocampus rarely develop electrical or chemical synapses with each other. Instead, they preferentially receive common synaptic input from nearby fast-spiking (FS), but not non-FS, interneurons and exhibit synchronous synaptic activity. These results suggest that shared inhibitory input may specify horizontally clustered sister excitatory neurons as functional units in the hippocampus.
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Affiliation(s)
- Hua-Tai Xu
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Zhi Han
- College of Software, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Peng Gao
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Shuijin He
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Zhizhong Li
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Wei Shi
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Oren Kodish
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Wei Shao
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Keith N Brown
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Kun Huang
- Department of Biomedical Informatics, The Ohio State University, 333 West 10(th) Avenue, Columbus, OH 43210, USA
| | - Song-Hai Shi
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA; Graduate Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.
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5
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Abstract
Whether cortical projection neurons (CPNs) are generated by multipotent or fate-restricted progenitors is not completely understood. In this issue of Neuron, Guo et al. (2013) provide evidence that mouse Fezf2-expressing radial glial cells are multipotent progenitors that sequentially generate all major CPN subtypes and glia.
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6
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Transcriptional programs in transient embryonic zones of the cerebral cortex defined by high-resolution mRNA sequencing. Proc Natl Acad Sci U S A 2011; 108:14950-5. [PMID: 21873192 DOI: 10.1073/pnas.1112213108] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Characterizing the genetic programs that specify development and evolution of the cerebral cortex is a central challenge in neuroscience. Stem cells in the transient embryonic ventricular and subventricular zones generate neurons that migrate across the intermediate zone to the overlying cortical plate, where they differentiate and form the neocortex. It is clear that not one but a multitude of molecular pathways are necessary to progress through each cellular milestone, yet the underlying transcriptional programs remain unknown. Here, we apply differential transcriptome analysis on microscopically isolated cell populations, to define five transcriptional programs that represent each transient embryonic zone and the progression between these zones. The five transcriptional programs contain largely uncharacterized genes in addition to transcripts necessary for stem cell maintenance, neurogenesis, migration, and differentiation. Additionally, we found intergenic transcriptionally active regions that possibly encode unique zone-specific transcripts. Finally, we present a high-resolution transcriptome map of transient zones in the embryonic mouse forebrain.
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7
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Sansom SN, Livesey FJ. Gradients in the brain: the control of the development of form and function in the cerebral cortex. Cold Spring Harb Perspect Biol 2010; 1:a002519. [PMID: 20066088 DOI: 10.1101/cshperspect.a002519] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In the developing brain, gradients are commonly used to divide neurogenic regions into distinct functional domains. In this article, we discuss the functions of morphogen and gene expression gradients in the assembly of the nervous system in the context of the development of the cerebral cortex. The cerebral cortex is a mammal-specific region of the forebrain that functions at the top of the neural hierarchy to process and interpret sensory information, plan and organize tasks, and to control motor functions. The mature cerebral cortex is a modular structure, consisting of anatomically and functionally distinct areas. Those areas of neurons are generated from a uniform neuroepithelial sheet by two forms of gradients: graded extracellular signals and a set of transcription factor gradients operating across the field of neocortical stem cells. Fgf signaling from the rostral pole of the cerebral cortex sets up gradients of expression of transcription factors by both activating and repressing gene expression. However, in contrast to the spinal cord and the early Drosophila embryo, these gradients are not subsequently resolved into molecularly distinct domains of gene expression. Instead, graded information in stem cells is translated into discrete, region-specific gene expression in the postmitotic neuronal progeny of the stem cells.
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Affiliation(s)
- Stephen N Sansom
- Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN
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8
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Jones EG, Rakic P. Radial columns in cortical architecture: it is the composition that counts. Cereb Cortex 2010; 20:2261-4. [PMID: 20667930 PMCID: PMC2936809 DOI: 10.1093/cercor/bhq127] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The function of any brain structure depends on its neuronal composition and on the pattern of its extrinsic and intrinsic excitatory and inhibitory synaptic connectivity. In this issue of Cerebral Cortex, 3 related papers provide the most comprehensive analysis to date of the cellular and synaptic relationships of a standard cortical column in the somatosensory cortex of the Wistar rat. It is hoped that understanding normal composition of this archetypical cortical column may help to explain its functional operations, expose subtle pathological changes that could cause abnormal sensory and cognitive functions, and provide insight into evolution of the cerebral cortex.
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Affiliation(s)
- Edward G Jones
- Center for Neuroscience, University of California, Davis, CA 95616, USA.
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9
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Integration of neuronal clones in the radial cortical columns by EphA and ephrin-A signalling. Nature 2009; 461:524-8. [PMID: 19759535 DOI: 10.1038/nature08362] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Accepted: 07/27/2009] [Indexed: 01/10/2023]
Abstract
The cerebral cortex is a laminated sheet of neurons composed of the arrays of intersecting radial columns. During development, excitatory projection neurons originating from the proliferative units at the ventricular surface of the embryonic cerebral vesicles migrate along elongated radial glial fibres to form a cellular infrastructure of radial (vertical) ontogenetic columns in the overlaying cortical plate. However, a subpopulation of these clonally related neurons also undergoes a short lateral shift and transfers from their parental to the neighbouring radial glial fibres, and intermixes with neurons originating from neighbouring proliferative units. This columnar organization acts as the primary information processing unit in the cortex. The molecular mechanisms, role and significance of this lateral dispersion for cortical development are not understood. Here we show that an Eph receptor A (EphA) and ephrin A (Efna) signalling-dependent shift in the allocation of clonally related neurons is essential for the proper assembly of cortical columns. In contrast to the relatively uniform labelling of the developing cortical plate by various molecular markers and retrograde tracers in wild-type mice, we found alternating labelling of columnar compartments in Efna knockout mice that are caused by impaired lateral dispersion of migrating neurons rather than by altered cell production or death. Furthermore, in utero electroporation showed that lateral dispersion depends on the expression levels of EphAs and ephrin-As during neuronal migration. This so far unrecognized mechanism for lateral neuronal dispersion seems to be essential for the proper intermixing of neuronal types in the cortical columns, which, when disrupted, might contribute to neuropsychiatric disorders associated with abnormal columnar organization.
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10
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Wang Q, Liu X, Ge R, Guan S, Zhu Y, Wang JH. The postnatal development of intrinsic properties and spike encoding at cortical GABAergic neurons. Biochem Biophys Res Commun 2008; 378:706-10. [PMID: 19059212 DOI: 10.1016/j.bbrc.2008.11.104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 11/18/2008] [Indexed: 10/21/2022]
Abstract
GABAergic neurons play a critical role in maintaining the homeostasis of brain functions for well-organized behaviors. It is not known about the dynamical change in signal encoding at these neurons during postnatal development. We investigated this issue at GFP-labeled GABAergic neurons by whole-cell recording in cortical slices of mice. Our results show that the ability of spike encoding at GABAergic neurons is improved during postnatal development. This change is associated with the reduction of refractory periods and threshold potentials of sequential spikes, as well as the improvement of linear correlations between intrinsic properties and spike capacity. Therefore, the postnatal maturation of the spike encoding capacity at GABAergic neurons will stabilize the excitatory state of cerebral cortex.
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Affiliation(s)
- Qiyi Wang
- Department of Physiology, Bengbu Medical College, Bengbu Anhui, China
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11
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12
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Miranda RC, Santillano DR, Camarillo C, Dohrman D. Modeling the impact of alcohol on cortical development in a dish: strategies from mapping neural stem cell fate. Methods Mol Biol 2008; 447:151-68. [PMID: 18369918 DOI: 10.1007/978-1-59745-242-7_12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
During the second trimester period, neuroepithelial stem cells give birth to millions of new neuroblasts, which migrate away from their germinal zones to populate the developing brain and terminally differentiate into neurons. During this period, large numbers of cells are also eliminated by programmed cell death. Therefore, the second trimester constitutes an important critical period for neuronal proliferation, migration, differentiation and apoptosis. Substantial evidence indicates that teratogens like ethanol can interfere with neuronal maturation. However, there is a paucity of good model systems to study early, second trimester events. In vivo models are inherently interpretatively complex because cell proliferation, migration, differentiation, and death mechanisms occur concurrently in regions like the cerebral cortex. This temporal overlap of multiple developmental critical periods makes it difficult to evaluate the relative vulnerability of any individual critical period. Our laboratory has elected to utilize fetal rodent cerebral cortical-derived neurosphere cultures as an experimental model of the second-trimester ventricular neuroepithelium. This model has enabled us to use flow cytometric approaches to identify neuroepithelial stem cell and progenitor sub-populations and to show that ethanol accelerates the maturation of neural stem cells. We have also developed a simplified mitogen-withdrawal/matrix-adhesion paradigm to model the exit of neuroepithelial cells from the ventricular zone towards the subventricular zone and cortical plate, and their maturation into multipolar neurons. We can treat neurosphere cultures with ethanol to mimic exposure during the period of neuroepithelial proliferation and by using the step-wise maturation model, ask questions about the impact of prior ethanol exposure on the subsequent maturation of neurons as they migrate and undergo terminal differentiation. The combination of neurosphere culture and stepwise maturation models will enable us to dissect out the contributions of specific developmental critical periods to the overall teratology of a drug of abuse like ethanol.
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Affiliation(s)
- Rajesh C Miranda
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M Health Science Center, College Station, TX, USA
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13
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Rakic P. The radial edifice of cortical architecture: from neuronal silhouettes to genetic engineering. BRAIN RESEARCH REVIEWS 2007; 55:204-19. [PMID: 17467805 PMCID: PMC2203611 DOI: 10.1016/j.brainresrev.2007.02.010] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 02/25/2007] [Accepted: 02/27/2007] [Indexed: 12/16/2022]
Abstract
The developmental principles that establish the columnar edifice of the cerebral cortex underlie its evolution and dictate its physiological operations and cognitive capacity. This article contrasts the initial discoveries made by Ramón y Cajal and his contemporaries, based on the ingenious interpretation of neuronal shapes and their relationships using the Golgi method, with new insights based on the application of the most advanced methods of molecular biology and genetics. We can now propose a realistic model of how the sequence of gene expression, cascade of multiple molecular pathways and cell-cell interactions establish the number of neurons, guide their migration and allocation into proper regions and determine their differentiation into specific phenotypes that establish specific synaptic connections. The findings obtained from different levels of analyses sustain the radial unit hypothesis as a useful framework for understanding the mechanisms of cortical development and its evolution as an organ of thought.
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Affiliation(s)
- Pasko Rakic
- Section of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
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14
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Wu SX, Goebbels S, Nakamura K, Nakamura K, Kometani K, Minato N, Kaneko T, Nave KA, Tamamaki N. Pyramidal neurons of upper cortical layers generated by NEX-positive progenitor cells in the subventricular zone. Proc Natl Acad Sci U S A 2005; 102:17172-7. [PMID: 16284248 PMCID: PMC1288007 DOI: 10.1073/pnas.0508560102] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Indexed: 11/18/2022] Open
Abstract
The generation of pyramidal neurons in the mammalian neocortex has been attributed to proliferating progenitor cells within the ventricular zone (VZ). Recently, the subventricular zone (SVZ) has been recognized as a possible source of migratory neurons in brain slice preparations, but the relevance of these observations for the developing neocortex in vivo remains to be defined. Here, we demonstrate that a subset of progenitor cells within the SVZ of the mouse neocortex can be molecularly defined by Cre recombinase expression under control of the NEX/Math2 locus, a neuronal basic helix-loop-helix gene that by itself is dispensable for cortical development. NEX-positive progenitors are generated by VZ cells, move into the SVZ, and undergo multiple asymmetrical and symmetrical cell divisions that produce a fraction of the neurons in the upper cortical layers. Our data suggest that NEX-positive progenitors within the SVZ are committed to a glutamatergic neuronal fate and have evolved to expand the number of cortical output neurons that is characteristic for the mammalian forebrain.
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Affiliation(s)
- Sheng-Xi Wu
- Department of Morphological Brain Science and Laboratory of Immunological Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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15
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Scotti Campos L. Evidence for astrocyte heterogeneity: a distinct subpopulation of protoplasmic-like glial cells is detected in transgenic mice expressing Lmo1-lacZ. Glia 2003; 43:195-207. [PMID: 12898699 DOI: 10.1002/glia.10254] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The adult mammalian central nervous system (CNS) contains a large number of different cell types, which arise from the ventricular (VZ) and subventricular zones during embryonic development. In this study, we used a transgenic mouse expressing Lmo1-LacZ from a randomly inserted promoter/reporter gene construct to identify a glial subpopulation. LMO1 is an LIM domain-containing protein, thought to act in protein-protein interactions. We found first that in the adult transgenic CNS, beta-galactosidase (beta-gal) was expressed in a specific subpopulation of protoplasmic-like cells, which did not express detectable levels of glial fibrilary acidic protein unless a lesion was produced. Secondly, during development, beta-gal(+) cells were found arising from discrete regions of the VZ. Taken together, these results identify a subpopulation of protoplasmic glial cells in the adult CNS and suggest that they arise from a restricted VZ region during CNS development.
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16
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Aller MI, Jones A, Merlo D, Paterlini M, Meyer AH, Amtmann U, Brickley S, Jolin HE, McKenzie ANJ, Monyer H, Farrant M, Wisden W. Cerebellar granule cell Cre recombinase expression. Genesis 2003; 36:97-103. [PMID: 12820171 DOI: 10.1002/gene.10204] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cerebellum maintains balance and orientation, refines motor action, stores motor memories, and contributes to the timing aspects of cognition. We generated two mouse lines for making Cre recombinase-mediated gene disruptions largely confined to adult cerebellar granule cells. For this purpose we chose the GABA(A) receptor alpha6 subunit gene, whose expression marks this cell type. Here we describe mouse lines expressing Cre recombinase generated by 1) Cre knocked into the native alpha6 subunit gene by homologous recombination in embryonic stem cells; and 2) Cre recombined into an alpha6 subunit gene carried on a bacterial artificial chromosome (BAC) genomic clone. The fidelity of Cre expression was tested by crossing the mouse lines with the ROSA26 reporter mice. The particular alpha6BAC clone we identified will be valuable for delivering other gene products to cerebellar granule cells.
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Affiliation(s)
- M I Aller
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK
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17
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Hamasaki T, Goto S, Nishikawa S, Ushio Y. Neuronal cell migration for the developmental formation of the mammalian striatum. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2003; 41:1-12. [PMID: 12505644 DOI: 10.1016/s0165-0173(02)00216-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mammalian striatum is the largest receptive component of the basal ganglia circuit. It is involved in the control of various aspects of motor, cognitive, and emotional functions. In the telencephalon, the striatum has a unique histological property totally different from the cortical area and its ontogenesis remains largely unknown. In this review, we introduce recent advances in the understanding of neuronal cell migration, one of the most critical processes in the early phase of histogenesis that occurs in the embryonic striatum. It appears that there are three major modes of neuronal cell migration in the developmental formation of the striatum. They are (radial) outward, tangential, and inward migration, supplying the striatum with projection neurons, interneurons, and early-generated transient neurons that originate in the preplate, respectively. We challenge the classical concept that the striatum is solely derived from the restricted germinal area located in the basal telencephalon by providing evidence that striatal development requires the intermixture of different types of neurons originating from distinct regions of the telencephalon.
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Affiliation(s)
- Tadashi Hamasaki
- Laboratory of Neurobiology, Department of Neurosurgery, Kumamoto University Medical School, 1-1-1 Honjo, 860-8556, Kumamoto, Japan
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18
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Fujimori K, Takauji R, Tamamaki N. Differential localization of high- and low-molecular-weight variants of microtubule-associated protein 2 in the developing rat telencephalon. J Comp Neurol 2002; 449:330-42. [PMID: 12115669 DOI: 10.1002/cne.10286] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Microtubule-associated protein 2 (MAP2) occurs in developing mammalian neuronal tissue as both high- and low-molecular-weight forms with temporally regulated expression. We studied the MAP2 expression in the developing rat telencephalon with monoclonal antibodies that recognized both the high- and low-molecular-weight forms of MAP2 variants or that specifically recognized high-molecular-weight forms of MAP2 variants. Differences in the staining patterns of these antibodies reflected differences in the distribution of the high- and low-molecular-weight MAP2s. The immunoreactive sites of high- and low-molecular-weight MAP2 had a more widespread distribution in the embryonic telencephalon than those of high-molecular-weight MAP2. Many bipolar cells in the ganglionic eminence (GE) and in the intermediate zone (IZ) of the neocortex showed low-molecular-weight MAP2 immunoreactivity, but they showed weak or no high-molecular-weight MAP2 immunoreactivity. Expression of mRNA containing exons common to high- and low-molecular-weight MAP2 was detected in the tangentially ellipsoidal cells in the IZ, but expression of mRNA containing an exon specific to high-molecular-weight MAP2 was not detected in these cells by in situ hybridization. We interpreted these observations as indicating that the bipolar cells contained MAP2c preferentially, but contained MAP2a and MAP2b (MAP2a/b) at a very low or negligible level. The cells that expressed MAP2c preferentially among the MAP2 splicing variants composed 50% of the preplate cells, most of the MAP2-positive cells in the hippocampus and the corpus callosum. Double labeling by DiI staining and Dlx2 immunohistochemistry, or by Dlx2 and MAP2 immunohistochemistry, revealed that most of the Dlx2-positive cells in the IZ expressed MAP2c preferentially at embryonic day 16. Another double-labeling study revealed that most GAD-positive cells in the preplate were MAP2a/b positive, whereas most GAD-positive cells in the IZ expressed MAP2c preferentially, with only a negligible level of MAP2a/b immunoreactivity. We conclude that MAP2 immunoreactivity in the IZ was localized in the tangentially migrating neurons. The tangentially migrating neurons seemed to acquire MAP2a/b immunoreactivity as they entered the preplate or cortical plate and developed into mature neurons. Radially migrating neurons in the IZ were MAP2 negative. After entering to the preplate or the cortical plate, they became MAP2a/b positive as they developed into mature neurons.
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Affiliation(s)
- Kazuhiro Fujimori
- Department of Anatomy, Fukui Medical University, Matsuoka, 910-1193 Fukui, Japan
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19
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Abstract
To correlate clonal patterns in the rat striatum with adult neuronal phenotypes, we labeled striatal progenitors between embryonic day 14 (E14) and E19 with a retroviral library encoding alkaline phosphatase. In the adult striatum, the majority of E14-labeled neurons (87%) were members of discrete horizontal or radial cell clusters. Radial clusters accounted for only 23% of cell clusters but >34% of labeled cells. Striatal clones also demonstrated an unexpected widespread pattern of clonal dispersion. The majority of striatal clones were widely dispersed within the striatum, and 80% of clones were part of even larger clones that included cortical interneurons. Finally, we observed that PCR-positive cortical interneurons were members of clones containing both interneurons and pyramids (44%), exclusively interneuron clones (24%), or combined striatal-cortical clones (16%), consistent with the view that cortical interneurons have multiple origins in differentially behaving progenitor cells. Our data are also consistent with the notion that similar mechanisms underpin striatal and cortical development.
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20
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Aboitiz F, Morales D, Montiel J. The inverted neurogenetic gradient of the mammalian isocortex: development and evolution. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 38:129-39. [PMID: 11750929 DOI: 10.1016/s0006-8993(01)02902-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this paper we review recent evidence on the molecular control of cell migration in the isocortex, and present an hypothesis for the evolutionary origin of the inside-out neurogenetic gradient of this structure. We suggest that there are at least two key factors involved in the acquisition of the inside-out gradient: (i) the expression of the protein reelin, which arrests the migration of cortical plate cells by detaching them from the radial glial fiber. This permits younger neurons to use the same fiber to migrate past the previous neurons; and (ii) the second factor is an intracellular signaling pathway dependent on a cyclin-dependent protein kinase (Cdk5). Cdk5 may work by inhibiting N-cadherin mediated cell aggregation as young cells cross the cortical plate, permitting them to move to the more superficial layers. Interestingly, the mutation in Cdk5 affects the migration of only those cells belonging to superficial layers, which are considered to be an evolutionary acquisition of the mammalian isocortex.
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Affiliation(s)
- F Aboitiz
- Programa de Morfología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, 1027 Independencia Ave., PO Box 70079, Santiago 7, Chile.
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21
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Frappé I, Gaillard A, Roger M. Attraction Exerted in Vivo by Grafts of Embryonic Neocortex on Developing Thalamic Axons. Exp Neurol 2001; 169:264-75. [PMID: 11358441 DOI: 10.1006/exnr.2001.7669] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a previous study we provided evidence that embryonic (E) day 16 frontal cortical cells grafted into the occipital cortex of newborn rats receive inputs from the ventrolateral (VL) and ventromedial (VM) thalamic nuclei which, normally, project to the frontal cortex (25). The present study was designed to examine further the conditions of development of the thalamic innervation of heterotopic neocortical grafts. We demonstrate that VL/VM axons do not provide transitory aberrant input to the occipital cortex either in intact newborn animals or in rats having received neonatal occipital lesion and subsequent graft of E16 occipital cells. These findings indicate, therefore, that the VL/VM projection to the graft does not result from the stabilization of an initial widespread cortical projection from these thalamic nuclei occurring either spontaneously or in response to the lesion and homotopic transplantation procedures. We also show that the VL/VM projection to frontal-to-occipital grafts develops within a few days posttransplantation and is maintained in adulthood. Finally, this study establishes that most VL/VM axons which enter the grafts are not collaterals of thalamofrontal axons. After having reached the cortex, they proceed caudally primarily within the infragranular layers. The findings of this and previous (25) in vivo studies for the first time provide evidence that developing thalamic axons have the capacity to respond to signals from grafts of E16 cortical cells and are capable of deviating their trajectory to establish contact with the grafts. Only those axons arising from thalamic nuclei appropriate for the cortical locus of origin of the grafted cells respond to the guidance signals. The mechanisms by which the thalamic axons find their way to the graft probably rely on cell-contact signaling and/or long-range attraction exerted by diffusible molecules.
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Affiliation(s)
- I Frappé
- Département des Neurosciences, CNRS, UMR 6558, Université de Poitiers, 86022 Poitiers Cedex, France
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22
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Abstract
Thalamic afferents are known to exert a control over the differentiation of cortical areas at late stages of development. Here, we show that thalamic afferents also influence early stages of corticogenesis at the level of the ventricular zone. Using an in vitro approach, we show that embryonic day 14 mouse thalamic axons release a diffusable factor that promotes the proliferation of cortical precursors over a restricted developmental window. The thalamic mitogenic effect on cortical precursors (1) shortens the total cell-cycle duration via a reduction of the G(1) phase; (2) facilitates the G(1)/S transition leading to an increase in proliferative divisions; (3) is significantly reduced by antibodies directed against bFGF; and (4) influences the proliferation of both glial and neuronal precursors and does not preclude the action of signals that induce differentiation in these two lineages. We have related these in vitro findings to the in vivo condition: the organotypic culture of cortical explants in which anatomical thalamocortical innervation is preserved shows significantly increased proliferation rates compared with cortical explants devoid of subcortical afferents. These results are in line with a number of studies at subcortical levels showing the control of neurogenesis via afferent fibers in both vertebrates and invertebrates. Specifically, they indicate the mechanisms whereby embryonic thalamic afferents contribute to the known early regionalization of the ventricular zone, which plays a major role in the specification of neocortical areas.
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23
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Dehay C, Savatier P, Cortay V, Kennedy H. Cell-cycle kinetics of neocortical precursors are influenced by embryonic thalamic axons. J Neurosci 2001; 21:201-14. [PMID: 11150337 PMCID: PMC6762433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Thalamic afferents are known to exert a control over the differentiation of cortical areas at late stages of development. Here, we show that thalamic afferents also influence early stages of corticogenesis at the level of the ventricular zone. Using an in vitro approach, we show that embryonic day 14 mouse thalamic axons release a diffusable factor that promotes the proliferation of cortical precursors over a restricted developmental window. The thalamic mitogenic effect on cortical precursors (1) shortens the total cell-cycle duration via a reduction of the G(1) phase; (2) facilitates the G(1)/S transition leading to an increase in proliferative divisions; (3) is significantly reduced by antibodies directed against bFGF; and (4) influences the proliferation of both glial and neuronal precursors and does not preclude the action of signals that induce differentiation in these two lineages. We have related these in vitro findings to the in vivo condition: the organotypic culture of cortical explants in which anatomical thalamocortical innervation is preserved shows significantly increased proliferation rates compared with cortical explants devoid of subcortical afferents. These results are in line with a number of studies at subcortical levels showing the control of neurogenesis via afferent fibers in both vertebrates and invertebrates. Specifically, they indicate the mechanisms whereby embryonic thalamic afferents contribute to the known early regionalization of the ventricular zone, which plays a major role in the specification of neocortical areas.
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Affiliation(s)
- C Dehay
- Institut National de la Santé et de la Recherche Médicale U371, Cerveau et Vision, 69500 Bron, France. National de la Recherche Scientifique Unité M
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24
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Rakic P. From spontaneous to induced neurological mutations: a personal witness of the ascent of the mouse model. Results Probl Cell Differ 2000; 30:1-19. [PMID: 10857183 DOI: 10.1007/978-3-540-48002-0_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- P Rakic
- Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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25
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Tamamaki N, Sugimoto Y, Tanaka K, Takauji R. Cell migration from the ganglionic eminence to the neocortex investigated by labeling nuclei with UV irradiation via a fiber-optic cable. Neurosci Res 1999; 35:241-51. [PMID: 10605947 DOI: 10.1016/s0168-0102(99)00089-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recent studies have shown that the ganglionic eminence is one of the sources of tangentially migrating cells in the developing neocortex. Since the migration of the DiI-labeled cells from the ganglionic eminence to the neocortex was not monitored by videomicroscopy in these reports, we devised a novel method to study cell migration in vitro and in vivo. The new method involves ultraviolet (UV) irradiation of the cells through a fiber-optic cable and subsequent identification of the irradiated cells on the basis of the formation of thymine dimers in the nuclei. First, we tested the new method (UV-thymine dimer-labeling method) by applying it to monitor the cell migration of neuronal precursor cells in the rostral migratory stream in the neonatal rat telencephalon. In vitro, UV irradiation for 1 s through the fiber-optic cable resulted in the formation of sufficient thymine dimers as to allow immunohistochemical detection after 6 h of incubation; a significant proportion of the irradiated cells continued to migrate in the same direction and at the same speed as those before irradiation. There was no significant difference in the cell migration distance over 6 h between cells exposed and not exposed to the UV irradiation in vitro. In vivo, this method revealed that three times as many cells in the subventricular zone of the olfactory bulb migrated rostrally as caudally. The new method also allowed us to measure the speed of cell migration, which was estimated to be about 70 microm/h at the maximum in the rostral direction. After these examinations of reliability of the method, we applied it to the rat embryo brain. One day after UV irradiation of the ganglionic eminence, labeled migrating cells were found in the striatum, in the internal capsule, and in the intermediate zone of the neocortex. The observation period of cell migration to the neocortex was extended by the use of a xeroderma pigmentosum group A gene mutant mouse, which lacked an ability to remove thymine dimer from the UV-irradiated nuclei. Two days after the UV irradiation, labeled migrating cells from the ganglionic eminence of the mutant mouse embryos were found both in the cortical plate and in the intermediate zone of the neocortex.
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Affiliation(s)
- N Tamamaki
- Department of Anatomy, Fukui Medical University, Japan.
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26
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The medial ganglionic eminence gives rise to a population of early neurons in the developing cerebral cortex. J Neurosci 1999. [PMID: 10479690 DOI: 10.1523/jneurosci.19-18-07881.1999] [Citation(s) in RCA: 474] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During development of the neocortex, the marginal zone (layer I) and the subplate (layer VII) are the first layers to form from a primordial plexiform neoropil. The cortical plate (layers II-VI) is subsequently established between these superficial and deep components of the primordial plexiform neuropil. Neurons in the early zones are thought to play important roles in the formation of the cortex: the Cajal-Retzius cells of the marginal zone are instrumental in neuronal migration and laminar formation, and cells of the subplate are involved in the formation of cortical connections. Using the fluorescent tracer 1,1'-dioctodecyl-3,3,3', 3'-tetramethylindocarbocyanine (DiI), we have shown here that a substantial proportion of neurons of the marginal zone, including cells with features of Cajal-Retzius cells, and of the subplate and lower intermediate zone are not born in the ventricular neuroepithelium but instead originate in the medial ganglionic eminence (MGE), the pallidal primordium. These neurons follow a tangential migratory route to their positions in the developing cortex. They express the neurotransmitter GABA but seem to lack the calcium binding protein calretinin; some migrating cells found in the marginal zone express reelin. In addition, migrating cells express the LIM-homeobox gene Lhx6, a characteristic marker of the MGE. It is suggested that this gene uniquely or in combination with other transcription factors may be involved in the decision of MGE cells to differentiate in situ or migrate to the neocortex.
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27
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Abstract
Formation of our highly structured human brain involves a cascade of events, including differentiation, fate determination, and migration of neural precursors. In humans, unlike many other organisms, the cerebral cortex is the largest component of the brain. As in other mammals, the human cerebral cortex is located on the surface of the telencephalon and generally consists of six layers that are formed in an orderly fashion. During neuronal development, newly born neurons, moving in a radial direction, must migrate through previously formed layers to reach their proper cortical position. This is one of several neuronal migration routes that takes place in the developing brain; other modes of migration are tangential. Abnormal neuronal migration may in turn result in abnormal development of the cortical layers and deleterious consequences, such as Lissencephaly. Lissencephaly, a severe brain malformation, can be caused by mutations in one of two known genes: LIS1 and doublecortin (DCX). Recent in vitro and in vivo studies, report on possible functions for these gene products.
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Affiliation(s)
- O Reiner
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel.
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28
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Lavdas AA, Grigoriou M, Pachnis V, Parnavelas JG. The medial ganglionic eminence gives rise to a population of early neurons in the developing cerebral cortex. J Neurosci 1999; 19:7881-8. [PMID: 10479690 PMCID: PMC6782477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/1999] [Revised: 06/25/1999] [Accepted: 06/30/1999] [Indexed: 02/13/2023] Open
Abstract
During development of the neocortex, the marginal zone (layer I) and the subplate (layer VII) are the first layers to form from a primordial plexiform neoropil. The cortical plate (layers II-VI) is subsequently established between these superficial and deep components of the primordial plexiform neuropil. Neurons in the early zones are thought to play important roles in the formation of the cortex: the Cajal-Retzius cells of the marginal zone are instrumental in neuronal migration and laminar formation, and cells of the subplate are involved in the formation of cortical connections. Using the fluorescent tracer 1,1'-dioctodecyl-3,3,3', 3'-tetramethylindocarbocyanine (DiI), we have shown here that a substantial proportion of neurons of the marginal zone, including cells with features of Cajal-Retzius cells, and of the subplate and lower intermediate zone are not born in the ventricular neuroepithelium but instead originate in the medial ganglionic eminence (MGE), the pallidal primordium. These neurons follow a tangential migratory route to their positions in the developing cortex. They express the neurotransmitter GABA but seem to lack the calcium binding protein calretinin; some migrating cells found in the marginal zone express reelin. In addition, migrating cells express the LIM-homeobox gene Lhx6, a characteristic marker of the MGE. It is suggested that this gene uniquely or in combination with other transcription factors may be involved in the decision of MGE cells to differentiate in situ or migrate to the neocortex.
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Affiliation(s)
- A A Lavdas
- Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
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29
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Zhu Y, Li H, Zhou L, Wu JY, Rao Y. Cellular and molecular guidance of GABAergic neuronal migration from an extracortical origin to the neocortex. Neuron 1999; 23:473-85. [PMID: 10433260 DOI: 10.1016/s0896-6273(00)80801-6] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Formation of the normal mammalian cerebral cortex requires the migration of GABAergic inhibitory interneurons from an extracortical origin, the lateral ganglionic eminence (LGE). Mechanisms guiding the migratory direction of these neurons, or other neurons in the neocortex, are not well understood. We have used an explant assay to study GABAergic neuronal migration and found that the ventricular zone (VZ) of the LGE is repulsive to GABAergic neurons. Furthermore, the secreted protein Slit is a chemorepellent guiding the migratory direction of GABAergic neurons, and blockade of endogenous Slit signaling inhibits the repulsive activity in the VZ. These results have revealed a cellular source of guidance for GABAergic neurons, demonstrated a molecular cue important for cortical development, and suggested a guidance mechanism for the migration of extracortical neurons into the neocortex.
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Affiliation(s)
- Y Zhu
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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30
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Leavitt BR, Hernit-Grant CS, Macklis JD. Mature astrocytes transform into transitional radial glia within adult mouse neocortex that supports directed migration of transplanted immature neurons. Exp Neurol 1999; 157:43-57. [PMID: 10222107 DOI: 10.1006/exnr.1999.6982] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neuronal migration is an essential step in normal mammalian neocortical development, and the expression of defined cellular and molecular signals within the developing cortical microenvironment is likely crucial to this process. Therapy via transplanted or manipulated endogenous precursors for diseases which involve neuronal loss may depend critically on whether newly incorporated cells can actively migrate to repopulate areas of neuronal loss within the adult brain. Previous studies demonstrated that embryonic neurons and multipotent precursors transplanted into the neocortex of adult mice undergoing targeted apoptosis of pyramidal neurons migrate long distances into neuron-deficient regions, undergo directed differentiation, accept afferent synaptic input, and make appropriate long-distance projections. The experiments presented here: (1) use time-lapse digital confocal imaging of neuronal migration in living slice cultures to assess cellular mechanisms utilized by immature neurons during such long distance migration, and (2) identify changes within the host cortical astroglial population that may contribute to this migration. Prelabeled embryonic day 17 mouse neocortical neurons were transplanted into adult mouse primary somatosensory cortex undergoing targeted apoptotic degeneration of callosal projection neurons. Four to 7 days following transplantation, living slice cultures containing the region of transplanted cells were prepared and observed. Sequential time-lapse images were recorded using a video-based digital confocal microscope. Transplanted cells displayed bipolar morphologies characteristic of migrating neuroblasts and moved in a saltatory manner with mean rates of up to 14 microm/h. To investigate whether a permissive glial phenotype may provide a potential substrate for this directed form of neuronal migration, slice cultures were immunostained with the RC2 monoclonal antibody, which identifies radial glia that act as a substrate for neuronal migration during corticogenesis. RC2 does not label mature stellate astrocytes, which express glial fibrillary acidic protein (GFAP). RC2 expression was observed in glial cells closely apposed to migrating donor neurons within the slice cultures. The timing and specificity of RC2 expression was examined immunocytochemically at various times following transplantation. RC2 immunostaining within regions of neuronal degeneration was transient, with peak staining between 3 and 7 days following transplantation. Strongly RC2-immunoreactive cells that did not express GFAP were found within these regions, but not in distant cortical regions or within control brains. RC2-positive cells were identified in recipient transgenic mice which express beta-galactosidase under a glial specific promoter. Coexpression of RC2 and beta-galactosidase identified these cells as host astroglia. These results demonstrate that adult cortical astrocytes retain the capacity to reexpress an earlier developmental phenotype that may partially underlie the observed active migration of transplanted neurons and neural precursors. Further understanding of these processes could allow directed migration of transplanted or endogenous precursors toward therapeutic cellular repopulation and complex circuit reconstruction in neocortex and other CNS regions.
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Affiliation(s)
- B R Leavitt
- Division of Neuroscience, Harvard Medical School and, Boston, Massachusetts 02115, USA
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31
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Jankovski A, Garcia C, Soriano E, Sotelo C. Proliferation, migration and differentiation of neuronal progenitor cells in the adult mouse subventricular zone surgically separated from its olfactory bulb. Eur J Neurosci 1998; 10:3853-68. [PMID: 9875362 DOI: 10.1046/j.1460-9568.1998.00397.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The subventricular zone of the adult mammalian forebrain contains progenitor cells that, by migrating along a restricted pathway called the 'rostral migratory stream' (RMS), add new neurons to the olfactory bulb throughout life. To determine the influence of the olfactory bulb on the development of these progenitor cells, we performed lesions that interrupt this pathway and separate the olfactory bulb from the rest of the forebrain. By labelling cells born at several survival times after the lesions with the thymidine analogue bromodeoxyuridine (BrdU), we found that disconnection from the bulb influences the rate of BrdU incorporation by the progenitor cells. The number of labelled cells in lesioned mice was almost half that found in control mice. In the disconnected migratory pathway, the number of neurons expressing calretinin was increased indicating that neuronal differentiation was enhanced: newly born neurons occurred within and around the RMS, most of them expressed calretinin and left the pathway starting about 2 weeks after the lesion. Thereafter, these neurons preserving their phenotype, spread for long distances, and accumulated ectopically in dorsal regions of the anterior olfactory nucleus and the frontal cortex. Finally, transplantation of adult subventricular cells into the lesioned pathway showed that the lesion neither prevents neuronal migration nor alters its direction. Thus, although the olfactory bulb appears to regulate the pace of the developmental processes, its disconnection does not prevent the proliferation, migration and phenotypic acquisition of newly generated bulbar interneurons that, since they cannot reach their terminal domains, populate some precise regions of the lesioned adult forebrain.
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32
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Létang J, Gaillard A, Roger M. Specific invasion of occipital-to-frontal neocortical grafts by axons from the lateral posterior thalamic nucleus consecutive to neonatal lesion of the rat occipital cortex. Exp Neurol 1998; 152:64-73. [PMID: 9682013 DOI: 10.1006/exnr.1998.6830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Previous work found that transplants of embryonic (E) day 16 occipital cortex placed into the frontal cortex of newborn hosts failed to receive input from visual-related nuclei of the host thalamus. The present study is aimed at determining the possible causes of the lack of visual-related thalamic input to these transplants. For that purpose, a retrograde neurotracer was injected into transplants of embryonic (E16) occipital origin which were placed into the frontal cortex of newborn rats with either intact or damaged occipital cortex. In rats with intact occipital cortex, occipital-to-frontal transplants were indeed not contacted by axons from the dorsal lateral geniculate (DLG) nucleus and received only sparse to negligible input from, respectively, the lateral posterior (LP) and laterodorsal (LD) thalamic nuclei. Yet, following neonatal lesion of the host occipital cortex, the occipital-to-frontal transplants received a significant input from the LP and to a much lesser degree from the LD but practically none from the DLG. Additional control cases with frontal-to-frontal transplants and prior lesion of the occipital cortex did not receive significant input from any of these thalamic nuclei. Thus, following neonatal deprivation of cortical target cells in their main terminal field, LP and to a lesser extent LD axons have the capacity to recognize and significantly innervate appropriate targets even those at some distance from their normal terminal site. DLG neurons degenerate or are not able to contact and invade available terminal space that is provided at some distance from the occipital cortex.
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Affiliation(s)
- J Létang
- Département des Neurosciences, Laboratoire de Neurophysiologie, Université de Poitiers, 40 Av. du Recteur Pineau, Poitiers Cedex, 86022, France
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33
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Supèr H, Soriano E, Uylings HB. The functions of the preplate in development and evolution of the neocortex and hippocampus. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1998; 27:40-64. [PMID: 9639671 DOI: 10.1016/s0165-0173(98)00005-8] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, it has been shown that the early developmental organization of the archicortical hippocampus resembles that of the neocortex. In both cortices at embryonic stages, a preplate is present, which is split by the formation of the cortical plate into a marginal zone and a subplate layer. The pioneer neurons of the preplate are believed to form a phylogenetically ancient cortical structure. Neurons in these preplate layers are the first postmitotic neurons and have important roles in the development of the cerebral cortex. Cajal-Retzius cells in the marginal zone regulate the phenotype of radial glial cells and may direct neuronal migration establishing the inside-out gradient of corticogenesis. Furthermore, pioneer neurons form the initial axonal connections with other (sub)cortical structures. A significant difference between the hippocampus and neocortex, however, is that in the hippocampus, most afferents are guided by the pioneer neurons in the prominent marginal zone, while in the neocortex most ingrowing afferent axons enter via the subplate. At later developmental periods, most pioneer neurons disappear by cell death or transform into other neuronal shapes. Here, we review the early developmental organization of the mammalian cerebral cortex (both neocortex and hippocampus) and discuss the functions and fate of pioneer neurons in cortical development, in particular that of Cajal-Retzius cells. Evaluating the developmental properties of the hippocampus and neocortex, we present the hypothesis that the distribution of the main ingrowing afferent systems in the developing neocortex, which differs from the one in the hippocampal region, may have enabled the specific evolution of the neocortex.
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Affiliation(s)
- H Supèr
- Department of Animal and Plant Cell Biology, Faculty of Biology, University of Barcelona, Spain
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34
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Arimatsu Y, Ishida M. Early patterning of the rat cerebral wall for regional organization of a neuronal population expressing latexin. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1998; 106:71-8. [PMID: 9554959 DOI: 10.1016/s0165-3806(97)00197-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The exact timing of regional patterning in the developing cerebral cortex and other telencephalic structures remains to be elucidated. In the present study, we addressed this issue by comparing the distribution and density of neuronal population expressing latexin in the adult rat telencephalon, with the regional pattern in the fetal cerebral wall as to the potential to generate latexin-expressing neurons. Immunohistochemical analyses on adult animals have shown that latexin-expressing neurons are restricted to a lateral cortical field, within which they are most abundant at the middle level, decreasing in number rostrally and caudally. Substantial numbers of latexin-immunopositive neurons were recorded in the claustrum and endopiriform nuclei, both of which are located from rostral to middle level in the lateral telencephalon. By examining the number and density of latexin-immunopositive neurons in organotypic slice cultures from various portions of the developing rat cerebral wall, it has been shown that the regional pattern within the early cerebral wall as to the potential to generate latexin-expressing neurons matches well the distribution and density of latexin-expressing neurons in the adult telencephalon. Thus, in cultures derived from either embryonic day 13 or 16 fetuses, latexin-immunopositive neurons appeared most prominently in those from rostral-to-middle portions of the lateral cerebral wall, decreasing in number rostrally and caudally. In cultures from the dorsal cerebral wall, the number was generally very low. In light of our previous finding that most prospective latexin-expressing neurons are still dividing at embryonic day 13, it can be concluded that some kind of pattern formation event occurs within the early cerebral wall even prior to the genesis of the postmitotic neurons that would be later allocated in a region-specific manner.
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Affiliation(s)
- Y Arimatsu
- Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan
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35
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Abstract
Neuroblasts produced in the ventricular zone of the neocortex migrate radially and form the cortical plate, settling in an inside-out order. It is also well known that the tangential cell migration is not negligible in the embryonic neocortex. To have a better understanding of the tangential cell migration in the cortex, we disturbed the migration by making a cut in the neocortex, and we labeled the migrating cells with 1,1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) in vivo and in vitro. We also determined the birth dates of the cells. Disturbance of tangential cell migration caused an accumulation and disappearance of microtubule-associated protein 2 immunoreactive (MAP2-IR) cells on the ventral and dorsal side of the cut, respectively, which indicated that most of the MAP2-IR cells in the intermediate zone (IZ) were migrating toward the dorsal cortex. The DiI injection study in vivo confirmed the tendency of the direction of cell migration and suggested the origin of the cells to be in the lateral ganglionic eminence (LGE). DiI injection into the LGE in vitro confirmed that the LGE cells cross the corticostriatal boundary and enter the IZ of the neocortex. The migrating cells acquired multipolar shape in the IZ of the dorsal cortex and seemed to reside there. A 5-bromo-deoxyuridine incorporation study revealed that the migrating MAP2-IR cells in the IZ were early-generated neurons. We concluded that the majority of tangentially migrating cells were generated in the LGE and identified as a distinct population that was assumed not to have joined the cortical plate.
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Cameron RS, Ruffin JW, Cho NK, Cameron PL, Rakic P. Developmental expression, pattern of distribution, and effect on cell aggregation implicate a neuron-glial junctional domain protein in neuronal migration. J Comp Neurol 1997. [DOI: 10.1002/(sici)1096-9861(19971103)387:4<467::aid-cne1>3.0.co;2-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Tamamaki N, Fujimori KE, Takauji R. Origin and route of tangentially migrating neurons in the developing neocortical intermediate zone. J Neurosci 1997; 17:8313-23. [PMID: 9334406 PMCID: PMC6573720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Neuroblasts produced in the ventricular zone of the neocortex migrate radially and form the cortical plate, settling in an inside-out order. It is also well known that the tangential cell migration is not negligible in the embryonic neocortex. To have a better understanding of the tangential cell migration in the cortex, we disturbed the migration by making a cut in the neocortex, and we labeled the migrating cells with 1,1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) in vivo and in vitro. We also determined the birth dates of the cells. Disturbance of tangential cell migration caused an accumulation and disappearance of microtubule-associated protein 2 immunoreactive (MAP2-IR) cells on the ventral and dorsal side of the cut, respectively, which indicated that most of the MAP2-IR cells in the intermediate zone (IZ) were migrating toward the dorsal cortex. The DiI injection study in vivo confirmed the tendency of the direction of cell migration and suggested the origin of the cells to be in the lateral ganglionic eminence (LGE). DiI injection into the LGE in vitro confirmed that the LGE cells cross the corticostriatal boundary and enter the IZ of the neocortex. The migrating cells acquired multipolar shape in the IZ of the dorsal cortex and seemed to reside there. A 5-bromo-deoxyuridine incorporation study revealed that the migrating MAP2-IR cells in the IZ were early-generated neurons. We concluded that the majority of tangentially migrating cells were generated in the LGE and identified as a distinct population that was assumed not to have joined the cortical plate.
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Affiliation(s)
- N Tamamaki
- Department of Anatomy, Fukui Medical School, Matsuoka, Fukui 910-11, Japan
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38
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Regulation of neuroblast cell-cycle kinetics plays a crucial role in the generation of unique features of neocortical areas. J Neurosci 1997. [PMID: 9315898 DOI: 10.1523/jneurosci.17-20-07763.1997] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cortical neurons are generated in the germinal zones lining the ventricles before migrating predominantly radially. To investigate regional differences in the cell-cycle kinetics of neuroblasts, pulse [3H]-thymidine injections were made throughout corticogenesis, and labeled neuron counts were compared in areas 3, 6, 17, and 18a in the adult mouse. The relationship between height in the cortex and intensity of autoradiographic signal distinguishes first generation and subsequent generations of neurons. This provides the mitotic history of defined sets of neurons and is a powerful tool for analyzing areal differences in cell-cycle kinetics. The infragranular laminar labeling indices of different generations show significant differences in areas 3 and 6. The labeling index of first generation neurons shows that the rate of neuron production is higher in area 3 than in area 6. This increased generation rate in area 3 was accompanied by two major changes. First, computation of the labeling index of the subsequent generation neurons (which reflects percentages of precursors in S-phase at the moment of the pulse) indicates a shorter cell cycle in area 3. Second, the total population of labeled neurons contains a higher proportion of first generation neurons in area 3, implying a higher leaving fraction in this area. Computer simulations of these areal differences of cell-cycle kinetics generate neuron numbers that are in close agreement with published data. Altogether these findings reveal an early regionalization of the ventricular zone that serves to generate unique features of future cortical areas.
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Polleux F, Dehay C, Moraillon B, Kennedy H. Regulation of neuroblast cell-cycle kinetics plays a crucial role in the generation of unique features of neocortical areas. J Neurosci 1997; 17:7763-83. [PMID: 9315898 PMCID: PMC6793912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cortical neurons are generated in the germinal zones lining the ventricles before migrating predominantly radially. To investigate regional differences in the cell-cycle kinetics of neuroblasts, pulse [3H]-thymidine injections were made throughout corticogenesis, and labeled neuron counts were compared in areas 3, 6, 17, and 18a in the adult mouse. The relationship between height in the cortex and intensity of autoradiographic signal distinguishes first generation and subsequent generations of neurons. This provides the mitotic history of defined sets of neurons and is a powerful tool for analyzing areal differences in cell-cycle kinetics. The infragranular laminar labeling indices of different generations show significant differences in areas 3 and 6. The labeling index of first generation neurons shows that the rate of neuron production is higher in area 3 than in area 6. This increased generation rate in area 3 was accompanied by two major changes. First, computation of the labeling index of the subsequent generation neurons (which reflects percentages of precursors in S-phase at the moment of the pulse) indicates a shorter cell cycle in area 3. Second, the total population of labeled neurons contains a higher proportion of first generation neurons in area 3, implying a higher leaving fraction in this area. Computer simulations of these areal differences of cell-cycle kinetics generate neuron numbers that are in close agreement with published data. Altogether these findings reveal an early regionalization of the ventricular zone that serves to generate unique features of future cortical areas.
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Affiliation(s)
- F Polleux
- Institut National de la Santé et de la Recherche Médicale U371-Cerveau et Vision, 69675 BRON Cedex, France
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Gaillard A, Létang J, Frappé I, Roger M. Abnormalities in the development of the tectal projection from transplants of embryonic occipital cortex placed in the damaged occipital cortex of newborn rats. Exp Neurol 1997; 147:476-86. [PMID: 9344571 DOI: 10.1006/exnr.1997.6606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have examined the degree of precision in the topographic arrangement of the tectal projection developed by homotopic transplants of embryonic occipital cortex and tried to determine whether the development of the corticotectal projection is exclusively dependent on environmental cues or is also controlled by intrinsic factors. Transplants of embryonic (E16) occipital cortex were grafted into various areas of the occipital cortex (Oc1 or Oc2) of newborn rats and the organization of the tectal projection arising from the transplants was subsequently examined by injecting different neurotracers into the transplants. Our results indicate that in most cases the laminar and tangential distributions of the tectal projections from the transplants were abnormal. Indeed, whatever the location of the transplant in the host occipital cortex and whatever the placement of the injection into the transplant, a hybrid distribution of the tectal labeling was found, reminiscent of the pattern observed following tracer deposits in both Oc1 and Oc2 in intact animals. Since the grafts were composed of cells of both Oc1 and Oc2 embryonic origin, it is likely that the hybrid pattern of efferents reflects the heterogeneity of the embryonic origin of the cells composing the graft. These findings provide evidence that the development of the topographic distribution of neocortical efferents is not only dependent on factors extrinsic to the cortex and further indicate that even within one single cortical region, the occipital cortex, different areas (Oc1 vs Oc2) are not totally interchangeable. These findings might have important implications in transplantation experiments aiming at the reconstruction of damaged neocortical circuitry where a precise "point-to-point" reconstruction of the circuitry is expected.
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Affiliation(s)
- A Gaillard
- UMR 6558, Département des Neurosciences, Université de Poitiers, France
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Polleux F, Dehay C, Kennedy H. The timetable of laminar neurogenesis contributes to the specification of cortical areas in mouse isocortex. J Comp Neurol 1997. [DOI: 10.1002/(sici)1096-9861(19970818)385:1<95::aid-cne6>3.0.co;2-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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42
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Sekerková G, Katarova Z, Joó F, Wolff JR, Prodan S, Szabó G. Visualization of beta-galactosidase by enzyme and immunohistochemistry in the olfactory bulb of transgenic mice carrying the LacZ transgene. J Histochem Cytochem 1997; 45:1147-55. [PMID: 9267475 DOI: 10.1177/002215549704500812] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In the olfactory bulb (OB) of a transgenic mouse line that carries the bacterial LacZ gene under the control of the 5'-regulatory region of the GAD67 gene, expression of the beta-galactosidase was confined almost exclusively to the non-GABAergic mitral and tufted cells. By light microscopy, enzyme histochemistry showed strong staining in the cell bodies and faint diffuse staining in the axons and dendrites. With immunohistochemistry for beta-galactosidase the entire cytoplasm, including the axons and dendrites, was strongly stained. By electron microscopy, beta-galactosidase enzyme histochemistry resulted in a submicroscopic reaction product that was diffusely distributed in the cytoplasm of neurons. In addition, large deposits of the reaction product were also seen attached to the cytoplasmic side of the membranes. In contrast, when the intracellular localization of beta-galactosidase was determined by immunohistochemistry, homogeneous cytoplasmic staining was obtained that filled the entire cytoplasm including the terminal dendrites and fine axons. Therefore, synaptic contacts of the beta-galactosidase-positive output neurons with other beta-galactosidase-negative neuronal cells were readily recognized in the OB. As we demonstrated, transgenic mouse lines expressing the LacZ reporter gene in a well-defined neuronal subpopulation can be used to follow beta-galactosidase-positive neurons and to directly identify their synaptic connections.
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Affiliation(s)
- G Sekerková
- Institute of Biochemistry, Hungarian Academy of Sciences, Szeged, Hungary
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43
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Reid CB, Tavazoie SF, Walsh CA. Clonal dispersion and evidence for asymmetric cell division in ferret cortex. Development 1997; 124:2441-50. [PMID: 9199370 DOI: 10.1242/dev.124.12.2441] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cell lineage analysis with retroviral libraries suggests that clonal progeny disperse widely in rodent cortex. To determine whether widespread dispersion is a general mammalian plan and to investigate phylogenetic differences in cortical development, we analyzed cell lineage in the ferret, a carnivore and near relative of the cat. The ferret possesses a highly developed, folded cerebral cortex, characteristic of higher mammalian species. Progenitor cells of the ferret cerebral cortex were tagged with an amphotropic retroviral library encoding alkaline phosphatase, and sibling relationships were determined using the polymerase chain reaction. Neuronal clones were single neurons (52%) or large clones (48%; average, 7 neurons) containing neurons and glia in widespread cortical locations. Neuronal clones in the ferret labeled at middle to late neurogenesis (embryonic day 33–35) contained large numbers of neurons and showed little tendency to cluster. The large proportion of single neuron clones, contrasted with the large size of multicell clones, suggests that some progenitors divide asymmetrically, producing a postmitotic neuron and regenerating a multipotential cell.
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Affiliation(s)
- C B Reid
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, Boston, MA 02115, USA
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44
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Karten HJ. Evolutionary developmental biology meets the brain: the origins of mammalian cortex. Proc Natl Acad Sci U S A 1997; 94:2800-4. [PMID: 9096300 PMCID: PMC34154 DOI: 10.1073/pnas.94.7.2800] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- H J Karten
- Department of Neurosciences, University of California at San Diego, La Jolla 92093-0608, USA
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Soriano E, Alvarado-Mallart RM, Dumesnil N, Del Río JA, Sotelo C. Cajal-Retzius cells regulate the radial glia phenotype in the adult and developing cerebellum and alter granule cell migration. Neuron 1997; 18:563-77. [PMID: 9136766 DOI: 10.1016/s0896-6273(00)80298-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Studies on the reeler mutation have shown that pioneer Cajal-Retzius (CR) cells are involved in neuronal migration in the developing cortex. Here, we use grafting and coculture experiments to investigate the mechanisms by which CR cells govern migration. We show that transplantation of embryonic CR cells, but not other cortical neurons, into adult cerebella induces a transient rejuvenation of host Bergmann glia into a radial glia phenotype. Similarly, CR cells sustain the phenotype of developing radial glia in postnatal cerebellar slices and induce the organization of a glial scaffold inside the CR cell explants. Studies with semipermeable inserts show that these effects are mediated by diffusible signals. We also show that CR cells adjacent to the surface of cerebellar slices reverse the direction of the migration of granule cells. Finally, CR cells from reeler mutant embryos elicited similar effects. These observations imply a role for CR cells in the regulation of the radial glia phenotype, a key step for neuronal migration, and suggest that these pioneer neurons may also exert a chemoattractive influence on migrating neurons.
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46
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O'Rourke NA, Chenn A, McConnell SK. Postmitotic neurons migrate tangentially in the cortical ventricular zone. Development 1997; 124:997-1005. [PMID: 9056775 DOI: 10.1242/dev.124.5.997] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Patterns of cell movement play a key role in the establishment of the brain's functional architecture during development. The migration of neuronal progenitor cells has been hypothesized to disperse clonally related cells among different areas of the developing cerebral cortex. To test this model, we explored the migratory patterns of cells in the proliferative zone of the intact cortex of the ferret. After focal injections of DiI, labeled cells migrated in all directions and over long distances within the ventricular and subventricular zones. These cells expressed the neuron-specific marker TuJ1 and did not incorporate BrdU after cumulative labeling. Our results reveal an extensive tangential dispersion of cortical cells mediated predominantly or exclusively by the non-radial migration of postmitotic neurons.
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Affiliation(s)
- N A O'Rourke
- Department of Biological Sciences, Stanford University, CA 94305, USA.
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47
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48
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Abstract
Regionalization of the cerebral cortex occurs during development by the formation of anatomically and functionally discrete areas of the brain. Descriptive evidence based on expression of molecules and structural features suggests that an early parcelation of the cerebral wall may occur during fetal development. Experimental strategies using tissue transplants and cell culture models have explored the nature of the timing of areal specification. New signaling systems displaying the sensitivity of precursor cells to environmental cues that define the fate of neurons destined for specific areas of the cortex have been discovered. Studies in the field now suggest mechanisms of regulating cell phenotype in the cortex that are common to all parts of the neuraxis.
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Affiliation(s)
- P Levitt
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, UMDNJ, Piscataway 08854, USA
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49
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Dehay C, Giroud P, Berland M, Killackey HP, Kennedy H. Phenotypic characterisation of respecified visual cortex subsequent to prenatal enucleation in the monkey: development of acetylcholinesterase and cytochrome oxidase patterns. J Comp Neurol 1996; 376:386-402. [PMID: 8956106 DOI: 10.1002/(sici)1096-9861(19961216)376:3<386::aid-cne3>3.0.co;2-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Prenatal bilateral enucleation induces cortex, which normally would have become striate cortex, to follow a default developmental pathway and to take on the cytoarchitectonic appearance of extrastriate cortex (default extrastriate cortex, Dehay et al. [1996] J. Comp. Neurol. 367:70-89). We have investigated if this manipulation influences the cortical expression of acetylcholinesterase (AChE) and cytochrome oxidase (CO). Early enucleation (before embryonic day 81; E81) had only minor effects on the distribution of AChE and CO in the striate cortex. In animals that underwent operation, the striate cortex CO blobs were significantly more closely spaced on the operculum compared with the calcarine. After early enucleation, there was a periodic distribution of CO dense patches in default extrastriate cortex. These CO patches had a center-to-center spacing that was considerably smaller than that of CO stripes in normal area V2, but was somewhat larger than that of the CO blobs in striate cortex. Although the CO stripes characteristic of normal area V2 could not be detected, there were some high-frequency CO patches, similar to those found in default extrastriate cortex. Early enucleation caused a failure to form the transient AChE bands running perpendicular to the striate border, which are normally present in the fetus and early neonate. Late enucleation did not alter AChE expression in extrastriate cortex. The relatively minor effects of early enucleation in the reduced striate cortex contrast with the changes in expression of these enzymes in extrastriate cortex, which accompany large shifts in the location of the striate border. This suggests a massive reorganisation of cortical phenotype in extrastriate cortex.
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Affiliation(s)
- C Dehay
- INSERM U371, Cerveau et Vision, France
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50
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Johe KK, Hazel TG, Muller T, Dugich-Djordjevic MM, McKay RD. Single factors direct the differentiation of stem cells from the fetal and adult central nervous system. Genes Dev 1996; 10:3129-40. [PMID: 8985182 DOI: 10.1101/gad.10.24.3129] [Citation(s) in RCA: 953] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Identifying the signals that regulate stem cell differentiation is fundamental to understanding cellular diversity in the brain. In this paper we identify factors that act in an instructive fashion to direct the differentiation of multipotential stem cells derived from the embryonic central nervous system (CNS). CNS stem cell clones differentiate to multiple fates: neurons, astrocytes, and oligodendrocytes. The differentiation of cells in a clone is influenced by extracellular signals: Platelet-derived growth factor (PDGF-AA, -AB, and -BB) supports neuronal differentiation. In contrast, ciliary neurotrophic factor and thyroid hormone T3 act instructively on stem cells to generate clones of astrocytes and oligodendrocytes, respectively. Adult stem cells had remarkably similar responses to these growth factors. These results support a simple model in which transient exposure to extrinsic factors acting through known pathways initiates fate decisions by multipotential CNS stem cells.
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Affiliation(s)
- K K Johe
- Laboratory of Molecular Biology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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