1
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Machold R, Rudy B. Genetic approaches to elucidating cortical and hippocampal GABAergic interneuron diversity. Front Cell Neurosci 2024; 18:1414955. [PMID: 39113758 PMCID: PMC11303334 DOI: 10.3389/fncel.2024.1414955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 07/08/2024] [Indexed: 08/10/2024] Open
Abstract
GABAergic interneurons (INs) in the mammalian forebrain represent a diverse population of cells that provide specialized forms of local inhibition to regulate neural circuit activity. Over the last few decades, the development of a palette of genetic tools along with the generation of single-cell transcriptomic data has begun to reveal the molecular basis of IN diversity, thereby providing deep insights into how different IN subtypes function in the forebrain. In this review, we outline the emerging picture of cortical and hippocampal IN speciation as defined by transcriptomics and developmental origin and summarize the genetic strategies that have been utilized to target specific IN subtypes, along with the technical considerations inherent to each approach. Collectively, these methods have greatly facilitated our understanding of how IN subtypes regulate forebrain circuitry via cell type and compartment-specific inhibition and thus have illuminated a path toward potential therapeutic interventions for a variety of neurocognitive disorders.
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Affiliation(s)
- Robert Machold
- Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, United States
| | - Bernardo Rudy
- Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, United States
- Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, United States
- Department of Anesthesiology, Perioperative Care and Pain Medicine, New York University Grossman School of Medicine, New York, NY, United States
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2
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Desiderio S, Schwaller F, Tartour K, Padmanabhan K, Lewin GR, Carroll P, Marmigere F. Touch receptor end-organ innervation and function require sensory neuron expression of the transcription factor Meis2. eLife 2024; 12:RP89287. [PMID: 38386003 PMCID: PMC10942617 DOI: 10.7554/elife.89287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024] Open
Abstract
Touch sensation is primarily encoded by mechanoreceptors, called low-threshold mechanoreceptors (LTMRs), with their cell bodies in the dorsal root ganglia. Because of their great diversity in terms of molecular signature, terminal endings morphology, and electrophysiological properties, mirroring the complexity of tactile experience, LTMRs are a model of choice to study the molecular cues differentially controlling neuronal diversification. While the transcriptional codes that define different LTMR subtypes have been extensively studied, the molecular players that participate in their late maturation and in particular in the striking diversity of their end-organ morphological specialization are largely unknown. Here we identified the TALE homeodomain transcription factor Meis2 as a key regulator of LTMRs target-field innervation in mice. Meis2 is specifically expressed in cutaneous LTMRs, and its expression depends on target-derived signals. While LTMRs lacking Meis2 survived and are normally specified, their end-organ innervations, electrophysiological properties, and transcriptome are differentially and markedly affected, resulting in impaired sensory-evoked behavioral responses. These data establish Meis2 as a major transcriptional regulator controlling the orderly formation of sensory neurons innervating peripheral end organs required for light touch.
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Affiliation(s)
- Simon Desiderio
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM U 1298MontpellierFrance
| | - Frederick Schwaller
- Department of Neuroscience, Max‐Delbrück Centre for Molecular MedicineBerlin‐BuchGermany
| | | | | | - Gary R Lewin
- Department of Neuroscience, Max‐Delbrück Centre for Molecular MedicineBerlin‐BuchGermany
| | - Patrick Carroll
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM U 1298MontpellierFrance
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3
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The P-body protein 4E-T represses translation to regulate the balance between cell genesis and establishment of the postnatal NSC pool. Cell Rep 2023; 42:112242. [PMID: 36924490 DOI: 10.1016/j.celrep.2023.112242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/19/2023] [Accepted: 02/23/2023] [Indexed: 03/17/2023] Open
Abstract
Here, we ask how developing precursors maintain the balance between cell genesis for tissue growth and establishment of adult stem cell pools, focusing on postnatal forebrain neural precursor cells (NPCs). We show that these NPCs are transcriptionally primed to differentiate and that the primed mRNAs are associated with the translational repressor 4E-T. 4E-T also broadly associates with other NPC mRNAs encoding transcriptional regulators, and these are preferentially depleted from ribosomes, consistent with repression. By contrast, a second translational regulator, Cpeb4, associates with diverse target mRNAs that are largely ribosome associated. The 4E-T-dependent mRNA association is functionally important because 4E-T knockdown or conditional knockout derepresses proneurogenic mRNA translation and perturbs maintenance versus differentiation of early postnatal NPCs in culture and in vivo. Thus, early postnatal NPCs are primed to differentiate, and 4E-T regulates the balance between cell genesis and stem cell expansion by sequestering and repressing mRNAs encoding transcriptional regulators.
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4
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Leung RF, George AM, Roussel EM, Faux MC, Wigle JT, Eisenstat DD. Genetic Regulation of Vertebrate Forebrain Development by Homeobox Genes. Front Neurosci 2022; 16:843794. [PMID: 35546872 PMCID: PMC9081933 DOI: 10.3389/fnins.2022.843794] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/14/2022] [Indexed: 01/19/2023] Open
Abstract
Forebrain development in vertebrates is regulated by transcription factors encoded by homeobox, bHLH and forkhead gene families throughout the progressive and overlapping stages of neural induction and patterning, regional specification and generation of neurons and glia from central nervous system (CNS) progenitor cells. Moreover, cell fate decisions, differentiation and migration of these committed CNS progenitors are controlled by the gene regulatory networks that are regulated by various homeodomain-containing transcription factors, including but not limited to those of the Pax (paired), Nkx, Otx (orthodenticle), Gsx/Gsh (genetic screened), and Dlx (distal-less) homeobox gene families. This comprehensive review outlines the integral role of key homeobox transcription factors and their target genes on forebrain development, focused primarily on the telencephalon. Furthermore, links of these transcription factors to human diseases, such as neurodevelopmental disorders and brain tumors are provided.
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Affiliation(s)
- Ryan F. Leung
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Ankita M. George
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Enola M. Roussel
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
| | - Maree C. Faux
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Surgery, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Jeffrey T. Wigle
- Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - David D. Eisenstat
- Murdoch Children’s Research Institute, The Royal Children’s Hospital Melbourne, Parkville, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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5
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Siskos N, Ververidis C, Skavdis G, Grigoriou ME. Genoarchitectonic Compartmentalization of the Embryonic Telencephalon: Insights From the Domestic Cat. Front Neuroanat 2022; 15:785541. [PMID: 34975420 PMCID: PMC8716433 DOI: 10.3389/fnana.2021.785541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/16/2021] [Indexed: 11/13/2022] Open
Abstract
The telencephalon develops from the alar plate of the secondary prosencephalon and is subdivided into two distinct divisions, the pallium, which derives solely from prosomere hp1, and the subpallium which derives from both hp1 and hp2 prosomeres. In this first systematic analysis of the feline telencephalon genoarchitecture, we apply the prosomeric model to compare the expression of a battery of genes, including Tbr1, Tbr2, Pax6, Mash1, Dlx2, Nkx2-1, Lhx6, Lhx7, Lhx2, and Emx1, the orthologs of which alone or in combination, demarcate molecularly distinct territories in other species. We characterize, within the pallium and the subpallium, domains and subdomains topologically equivalent to those previously described in other vertebrate species and we show that the overall genoarchitectural map of the E26/27 feline brain is highly similar to that of the E13.5/E14 mouse. In addition, using the same approach at the earlier (E22/23 and E24/25) or later (E28/29 and E34/35) stages we further analyze neurogenesis, define the timing and duration of several developmental events, and compare our data with those from similar mouse studies; our results point to a complex pattern of heterochronies and show that, compared with the mouse, developmental events in the feline telencephalon span over extended periods suggesting that cats may provide a useful animal model to study brain patterning in ontogenesis and evolution.
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Affiliation(s)
- Nikistratos Siskos
- Laboratory of Developmental Biology & Molecular Neurobiology, Department of Molecular Biology & Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Charalampos Ververidis
- Obstetrics and Surgery Unit, Companion Animal Clinic, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - George Skavdis
- Laboratory of Molecular Regulation & Diagnostic Technology, Department of Molecular Biology & Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Maria E Grigoriou
- Laboratory of Developmental Biology & Molecular Neurobiology, Department of Molecular Biology & Genetics, Democritus University of Thrace, Alexandroupolis, Greece
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6
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Kuerbitz J, Madhavan M, Ehrman LA, Kohli V, Waclaw RR, Campbell K. Temporally Distinct Roles for the Zinc Finger Transcription Factor Sp8 in the Generation and Migration of Dorsal Lateral Ganglionic Eminence (dLGE)-Derived Neuronal Subtypes in the Mouse. Cereb Cortex 2020; 31:1744-1762. [PMID: 33230547 DOI: 10.1093/cercor/bhaa323] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/07/2020] [Accepted: 10/07/2020] [Indexed: 12/29/2022] Open
Abstract
Progenitors in the dorsal lateral ganglionic eminence (dLGE) are known to give rise to olfactory bulb (OB) interneurons and intercalated cells (ITCs) of the amygdala. The dLGE enriched transcription factor Sp8 is required for the normal generation of ITCs as well as OB interneurons, particularly the calretinin (CR)-expressing subtype. In this study, we used a genetic gain-of-function approach in mice to examine the roles Sp8 plays in controlling the development of dLGE-derived neuronal subtypes. Misexpression of Sp8 throughout the ventral telencephalic subventricular zone (SVZ) from early embryonic stages, led to an increased generation of ITCs which was dependent on Tshz1 gene dosage. Additionally, Sp8 misexpression impaired rostral migration of OB interneurons with clusters of CR interneurons seen in the SVZ along with decreased differentiation of calbindin OB interneurons. Sp8 misexpression throughout the ventral telencephalon also reduced ventral LGE neuronal subtypes including striatal projection neurons. Delaying Sp8 misexpression until E14-15 rescued the striatal and amygdala phenotypes but only partially rescued OB interneuron reductions, consistent with an early window of striatal and amygdala neurogenesis and ongoing OB interneuron generation at this late stage. Our results demonstrate critical roles for the timing and neuronal cell-type specificity of Sp8 expression in mouse LGE neurogenesis.
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Affiliation(s)
- J Kuerbitz
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Medical-Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - M Madhavan
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - L A Ehrman
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Divisions of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - V Kohli
- Divisions of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - R R Waclaw
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Divisions of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - K Campbell
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Divisions of Neurosurgery, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
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7
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Castagnola S, Cazareth J, Lebrigand K, Jarjat M, Magnone V, Delhaye S, Brau F, Bardoni B, Maurin T. Agonist-induced functional analysis and cell sorting associated with single-cell transcriptomics characterizes cell subtypes in normal and pathological brain. Genome Res 2020; 30:1633-1642. [PMID: 32973039 PMCID: PMC7605246 DOI: 10.1101/gr.262717.120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 09/23/2020] [Indexed: 12/31/2022]
Abstract
To gain better insight into the dynamic interaction between cells and their environment, we developed the agonist-induced functional analysis and cell sorting (aiFACS) technique, which allows the simultaneous recording and sorting of cells in real-time according to their immediate and individual response to a stimulus. By modulating the aiFACS selection parameters, testing different developmental times, using various stimuli, and multiplying the analysis of readouts, it is possible to analyze cell populations of any normal or pathological tissue. The association of aiFACS with single-cell transcriptomics allows the construction of functional tissue cartography based on specific pharmacological responses of cells. As a proof of concept, we used aiFACS on the dissociated mouse brain, a highly heterogeneous tissue, enriching it in interneurons by stimulation with KCl or with AMPA, an agonist of the glutamate receptors, followed by sorting based on calcium levels. After AMPA stimulus, single-cell transcriptomics of these aiFACS-selected interneurons resulted in a nine-cluster classification. Furthermore, we used aiFACS on interneurons derived from the brain of the Fmr1-KO mouse, a rodent model of fragile X syndrome. We showed that these interneurons manifest a generalized defective response to AMPA compared with wild-type cells, affecting all the analyzed cell clusters at one specific postnatal developmental time.
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Affiliation(s)
- Sara Castagnola
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Julie Cazareth
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Kevin Lebrigand
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Marielle Jarjat
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Virginie Magnone
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Sébastien Delhaye
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Frederic Brau
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Barbara Bardoni
- Université Côte d'Azur, INSERM, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
| | - Thomas Maurin
- Université Côte d'Azur, CNRS, Institute of Molecular Cellular Pharmacology, F-06560 Valbonne, France
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8
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Guo T, Liu G, Du H, Wen Y, Wei S, Li Z, Tao G, Shang Z, Song X, Zhang Z, Xu Z, You Y, Chen B, Rubenstein JL, Yang Z. Dlx1/2 are Central and Essential Components in the Transcriptional Code for Generating Olfactory Bulb Interneurons. Cereb Cortex 2019; 29:4831-4849. [PMID: 30796806 PMCID: PMC6917526 DOI: 10.1093/cercor/bhz018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 01/03/2019] [Accepted: 01/26/2019] [Indexed: 12/22/2022] Open
Abstract
Generation of olfactory bulb (OB) interneurons requires neural stem/progenitor cell specification, proliferation, differentiation, and young interneuron migration and maturation. Here, we show that the homeobox transcription factors Dlx1/2 are central and essential components in the transcriptional code for generating OB interneurons. In Dlx1/2 constitutive null mutants, the differentiation of GSX2+ and ASCL1+ neural stem/progenitor cells in the dorsal lateral ganglionic eminence is blocked, resulting in a failure of OB interneuron generation. In Dlx1/2 conditional mutants (hGFAP-Cre; Dlx1/2F/- mice), GSX2+ and ASCL1+ neural stem/progenitor cells in the postnatal subventricular zone also fail to differentiate into OB interneurons. In contrast, overexpression of Dlx1&2 in embryonic mouse cortex led to ectopic production of OB-like interneurons that expressed Gad1, Sp8, Sp9, Arx, Pbx3, Etv1, Tshz1, and Prokr2. Pax6 mutants generate cortical ectopia with OB-like interneurons, but do not do so in compound Pax6; Dlx1/2 mutants. We propose that DLX1/2 promote OB interneuron development mainly through activating the expression of Sp8/9, which further promote Tshz1 and Prokr2 expression. Based on this study, in combination with earlier ones, we propose a transcriptional network for the process of OB interneuron development.
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Affiliation(s)
- Teng Guo
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Guoping Liu
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Heng Du
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Yan Wen
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Song Wei
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Zhenmeiyu Li
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Guangxu Tao
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Zicong Shang
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Xiaolei Song
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Zhuangzhi Zhang
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Zhejun Xu
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Yan You
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
| | - Bin Chen
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, CA 95064, USA
| | - John L Rubenstein
- Department of Psychiatry, Nina Ireland Laboratory of Developmental Neurobiology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, CA 94158, USA
| | - Zhengang Yang
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, MOE Frontier Research Center for Brain Science, Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai 200032, PR China
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9
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Hirata T, Shioi G, Abe T, Kiyonari H, Kato S, Kobayashi K, Mori K, Kawasaki T. A Novel Birthdate-Labeling Method Reveals Segregated Parallel Projections of Mitral and External Tufted Cells in the Main Olfactory System. eNeuro 2019; 6:ENEURO.0234-19.2019. [PMID: 31672846 PMCID: PMC6868177 DOI: 10.1523/eneuro.0234-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/16/2019] [Accepted: 10/19/2019] [Indexed: 01/09/2023] Open
Abstract
A fundamental strategy in sensory coding is parallel processing, whereby unique, distinct features of sensation are computed and projected to the central target in the form of submodal maps. It remains unclear, however, whether such parallel processing strategy is employed in the main olfactory system, which codes the complex hierarchical odor and behavioral scenes. A potential scheme is that distinct subsets of projection neurons in the olfactory bulb (OB) form parallel projections to the targets. Taking advantage of the observation that the distinct projection neurons develop at different times, we developed a Cre-loxP-based method that allows for birthdate-specific labeling of cell bodies and their axon projections in mice. This birthdate tag analysis revealed that the mitral cells (MCs) born in an early developmental stage and the external tufted cells (TCs) born a few days later form segregated parallel projections. Specifically, the latter subset converges the axons onto only two small specific targets, one of which, located at the anterolateral edge of the olfactory tubercle (OT), excludes widespread MC projections. This target is made up of neurons that express dopamine D1 but not D2 receptor and corresponds to the most anterolateral isolation of the CAP compartments (aiCAP) that were defined previously. This finding of segregated projections suggests that olfactory sensing does indeed involve parallel processing of functionally distinct submodalities. Importantly, the birthdate tag method used here may pave the way for deciphering the functional meaning of these individual projection pathways in the future.
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Affiliation(s)
- Tatsumi Hirata
- Brain Function Laboratory, National Institute of Genetics
- Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
| | - Go Shioi
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Takaya Abe
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
- Laboratory for Animal Resource Development, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Hiroshi Kiyonari
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
- Laboratory for Animal Resource Development, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Shigeki Kato
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Kazuto Kobayashi
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Kensaku Mori
- Department of Physiology, Graduate School of Medicine, the University of Tokyo, Tokyo 113-0033, Japan
| | - Takahiko Kawasaki
- Brain Function Laboratory, National Institute of Genetics
- Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
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10
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Scheimann JR, Mahbod P, Morano R, Frantz L, Packard B, Campbell K, Herman JP. Deletion of Glucocorticoid Receptors in Forebrain GABAergic Neurons Alters Acute Stress Responding and Passive Avoidance Behavior in Female Mice. Front Behav Neurosci 2018; 12:325. [PMID: 30627088 PMCID: PMC6309161 DOI: 10.3389/fnbeh.2018.00325] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/10/2018] [Indexed: 01/16/2023] Open
Abstract
The glucocorticoid receptor (GR) is critically involved in regulation of stress responses [inhibition of the hypothalamic-pituitary-adrenal (HPA) axis], emotional behavior and cognition via interactions with forebrain corticolimbic circuity. Work to date has largely focused on GR actions in forebrain excitatory neurons; however, recent studies suggest a potential role mediated by interneurons. Here, we targeted GR deletion in forebrain GABAergic neurons, including the cortical interneurons, using a Dlx5/6-Cre driver line to test the role of forebrain interneuronal GR in HPA axis regulation and behavior. Our data indicate that GR deletion in GABAergic neurons causes elevated corticosterone stress responsiveness and decreased cross-over latencies in a passive avoidance task in females, but not males. Dlx5/6-Cre driven gene deletion caused loss of GR in interneurons in the prefrontal cortex (PFC) and hippocampus, but also in select diencephalic GABAergic neurons (including the reticular thalamic nucleus and dorsomedial hypothalamus). Our data suggest that GR signaling in interneurons is differentially important in females, which may have implications for GR-directed therapies for stress-related affective disease states.
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Affiliation(s)
- Jessie R Scheimann
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Parinaz Mahbod
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Rachel Morano
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Lindsey Frantz
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Ben Packard
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
| | - Kenneth Campbell
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - James P Herman
- Department of Pharmacology and Systems Physiology, University of Cincinnati, Cincinnati, OH, United States
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11
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DMRT5, DMRT3, and EMX2 Cooperatively Repress Gsx2 at the Pallium-Subpallium Boundary to Maintain Cortical Identity in Dorsal Telencephalic Progenitors. J Neurosci 2018; 38:9105-9121. [PMID: 30143575 DOI: 10.1523/jneurosci.0375-18.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/23/2018] [Accepted: 08/15/2018] [Indexed: 11/21/2022] Open
Abstract
Specification of dorsoventral regional identity in progenitors of the developing telencephalon is a first pivotal step in the development of the cerebral cortex and basal ganglia. Previously, we demonstrated that the two zinc finger doublesex and mab-3 related (Dmrt) genes, Dmrt5 (Dmrta2) and Dmrt3, which are coexpressed in high caudomedial to low rostrolateral gradients in the cerebral cortical primordium, are separately needed for normal formation of the cortical hem, hippocampus, and caudomedial neocortex. We have now addressed the role of Dmrt3 and Dmrt5 in controlling dorsoventral division of the telencephalon in mice of either sex by comparing the phenotypes of single knock-out (KO) with double KO embryos and by misexpressing Dmrt5 in the ventral telencephalon. We find that DMRT3 and DMRT5 act as critical regulators of progenitor cell dorsoventral identity by repressing ventralizing regulators. Early ventral fate transcriptional regulators expressed in the dorsal lateral ganglionic eminence, such as Gsx2, are upregulated in the dorsal telencephalon of Dmrt3;Dmrt5 double KO embryos and downregulated when ventral telencephalic progenitors express ectopic Dmrt5 Conditional overexpression of Dmrt5 throughout the telencephalon produces gene expression and structural defects that are highly consistent with reduced GSX2 activity. Further, Emx2;Dmrt5 double KO embryos show a phenotype similar to Dmrt3;Dmrt5 double KO embryos, and both DMRT3, DMRT5 and the homeobox transcription factor EMX2 bind to a ventral telencephalon-specific enhancer in the Gsx2 locus. Together, our findings uncover cooperative functions of DMRT3, DMRT5, and EMX2 in dividing dorsal from ventral in the telencephalon.SIGNIFICANCE STATEMENT We identified the DMRT3 and DMRT5 zinc finger transcription factors as novel regulators of dorsoventral patterning in the telencephalon. Our data indicate that they have overlapping functions and compensate for one another. The double, but not the single, knock-out produces a dorsal telencephalon that is ventralized, and olfactory bulb tissue takes over most remaining cortex. Conversely, overexpressing Dmrt5 throughout the telencephalon causes expanded expression of dorsal gene determinants and smaller olfactory bulbs. Furthermore, we show that the homeobox transcription factor EMX2 that is coexpressed with DMRT3 and DMRT5 in cortical progenitors cooperates with them to maintain dorsoventral patterning in the telencephalon. Our study suggests that DMRT3/5 function with EMX2 in positioning the pallial-subpallial boundary by antagonizing the ventral homeobox transcription factor GSX2.
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12
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Zbtb20 Regulates Developmental Neurogenesis in the Olfactory Bulb and Gliogenesis After Adult Brain Injury. Mol Neurobiol 2018; 56:567-582. [DOI: 10.1007/s12035-018-1104-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 05/03/2018] [Indexed: 01/02/2023]
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13
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Memic F, Knoflach V, Morarach K, Sadler R, Laranjeira C, Hjerling-Leffler J, Sundström E, Pachnis V, Marklund U. Transcription and Signaling Regulators in Developing Neuronal Subtypes of Mouse and Human Enteric Nervous System. Gastroenterology 2018; 154:624-636. [PMID: 29031500 PMCID: PMC6381388 DOI: 10.1053/j.gastro.2017.10.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/03/2017] [Accepted: 10/04/2017] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS The enteric nervous system (ENS) regulates gastrointestinal function via different subtypes of neurons, organized into fine-tuned neural circuits. It is not clear how cell diversity is created within the embryonic ENS; information required for development of cell-based therapies and models of enteric neuropathies. We aimed to identify proteins that regulate ENS differentiation and network formation. METHODS We generated and compared RNA expression profiles of the entire ENS, ENS progenitor cells, and non-ENS gut cells of mice, collected at embryonic days 11.5 and 15.5, when different subtypes of neurons are formed. Gastrointestinal tissues from R26ReYFP reporter mice crossed to Sox10-CreERT2 or Wnt1-Cre mice were dissected and the 6 populations of cells were isolated by flow cytometry. We used histochemistry to map differentially expressed proteins in mouse and human gut tissues at different stages of development, in different regions. We examined enteric neuronal diversity and gastric function in Wnt1-Cre x Sox6fl/fl mice, which do not express the Sox6 gene in the ENS. RESULTS We identified 147 transcription and signaling factors that varied in spatial and temporal expression during development of the mouse ENS. Of the factors also analyzed in human ENS, most were conserved. We uncovered 16 signaling pathways (such as fibroblast growth factor and Eph/ephrin pathways). Transcription factors were grouped according to their specific expression in enteric progenitor cells (such as MEF2C), enteric neurons (such as SOX4), or neuron subpopulations (such as SATB1 and SOX6). Lack of SOX6 in the ENS reduced the numbers of gastric dopamine neurons and delayed gastric emptying. CONCLUSIONS Using transcriptome and histochemical analyses of the developing mouse and human ENS, we mapped expression patterns of transcription and signaling factors. Further studies of these candidate determinants might elucidate the mechanisms by which enteric stem cells differentiate into neuronal subtypes and form distinct connectivity patterns during ENS development. We found expression of SOX6 to be required for development of gastric dopamine neurons.
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Affiliation(s)
- Fatima Memic
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Viktoria Knoflach
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Khomgrit Morarach
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Rebecca Sadler
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Catia Laranjeira
- Division of Molecular Neurobiology, National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Jens Hjerling-Leffler
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Erik Sundström
- Division of Neurodegeneration, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden,Stockholms Sjukhem, Stockholm, Sweden
| | | | - Ulrika Marklund
- Division of Molecular Neurobiology, Department for Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
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14
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Ruiz-Reig N, Studer M. Rostro-Caudal and Caudo-Rostral Migrations in the Telencephalon: Going Forward or Backward? Front Neurosci 2017; 11:692. [PMID: 29311773 PMCID: PMC5742585 DOI: 10.3389/fnins.2017.00692] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/23/2017] [Indexed: 11/13/2022] Open
Abstract
The generation and differentiation of an appropriate number of neurons, as well as its distribution in different parts of the brain, is crucial for the proper establishment, maintenance and plasticity of neural circuitries. Newborn neurons travel along the brain in a process known as neuronal migration, to finalize their correct position in the nervous system. Defects in neuronal migration produce abnormalities in the brain that can generate neurodevelopmental pathologies, such as autism, schizophrenia and intellectual disability. In this review, we present an overview of the developmental origin of the different telencephalic subdivisions and a description of migratory pathways taken by distinct neural populations traveling long distances before reaching their target position in the brain. In addition, we discuss some of the molecules implicated in the guidance of these migratory paths and transcription factors that contribute to the correct migration and integration of these neurons.
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15
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Kohli V, Nardini D, Ehrman LA, Waclaw RR. Characterization of Glcci1 expression in a subpopulation of lateral ganglionic eminence progenitors in the mouse telencephalon. Dev Dyn 2017; 247:222-228. [PMID: 28744915 DOI: 10.1002/dvdy.24556] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND The lateral ganglionic eminence (LGE) in the ventral telencephalon is a diverse progenitor domain subdivided by distinct gene expression into a dorsal region (dLGE) that gives rise to olfactory bulb and amygdalar interneurons and a ventral region (vLGE) that gives rise to striatal projection neurons. The homeobox gene, Gsx2, is an enriched marker of the LGE and is expressed in a high dorsal to low ventral gradient in the ventricular zone (VZ) as development proceeds. Aside from Gsx2, markers restricted to the VZ in the dLGE and/or vLGE remain largely unknown. RESULTS Here, we show that the gene and protein expression of Glucocorticoid-induced transcript 1 (Glcci1) has a similar dorsal to ventral gradient of expression in the VZ as Gsx2. We found that Glcci1 gene and protein expression are reduced in Gsx2 mutants, and are increased in the cortex after early and late Gsx2 misexpression. Moreover, Glcci1 expressing cells are restricted to a subpopulation of Gsx2 positive cells on the basal side of the VZ and co-express Ascl1, but not the subventricular zone dLGE marker, Sp8. CONCLUSIONS These findings suggest that Glcci1 is a new marker of a subpopulation of LGE VZ progenitor cells in the Gsx2 lineage. Developmental Dynamics 247:222-228, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Vikram Kohli
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Diana Nardini
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Lisa A Ehrman
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Ronald R Waclaw
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio.,Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
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16
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Qin S, Ware SM, Waclaw RR, Campbell K. Septal contributions to olfactory bulb interneuron diversity in the embryonic mouse telencephalon: role of the homeobox gene Gsx2. Neural Dev 2017; 12:13. [PMID: 28814342 PMCID: PMC5559835 DOI: 10.1186/s13064-017-0090-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 08/01/2017] [Indexed: 11/17/2022] Open
Abstract
Background Olfactory bulb (OB) interneurons are known to represent diverse neuronal subtypes, which are thought to originate from a number of telencephalic regions including the embryonic dorsal lateral ganglionic eminence (dLGE) and septum. These cells migrate rostrally toward the OB, where they then radially migrate to populate different OB layers including the granule cell layer (GCL) and the outer glomerular layer (GL). Although previous studies have attempted to investigate regional contributions to OB interneuron diversity, few genetic tools have been used to address this question at embryonic time points when the earliest populations are specified. Methods In this study, we utilized Zic3-lacZ and Gsx2e-CIE transgenic mice as genetic fate-mapping tools to study OB interneuron contributions derived from septum and LGE, respectively. Moreover, to address the regional (i.e. septal) requirements of the homeobox gene Gsx2 for OB interneuron diversity, we conditionally inactivated Gsx2 in the septum, leaving it largely intact in the dLGE, by recombining the Gsx2 floxed allele using Olig2Cre/+ mice. Results Our fate mapping studies demonstrated that the dLGE and septum gave rise to OB interneuron subtypes differently. Notably, the embryonic septum was found to give rise largely to the calretinin+ (CR+) GL subtype, while the dLGE was more diverse, generating all major GL subpopulations as well as many GCL interneurons. Moreover, Gsx2 conditional mutants (cKOs), with septum but not dLGE recombination, showed impaired generation of CR+ interneurons within the OB GL. These Gsx2 cKOs exhibited reduced proliferation within the septal subventricular zone (SVZ), which correlated well with the reduced number of CR+ interneurons observed. Conclusions Our findings indicate that the septum and LGE contribute differently to OB interneuron diversity. While the dLGE provides a wide range of OB interneuron subtypes, the septum is more restricted in its contribution to the CR+ subtype. Gsx2 is required in septal progenitors for the correct expansion of SVZ progenitors specified toward the CR+ subtype. Finally, the septum has been suggested to be the exclusive source of CR+ interneurons in postnatal studies. Our results here demonstrate that dLGE progenitors in the embryo also contribute to this OB neuronal subtype. Electronic supplementary material The online version of this article (doi:10.1186/s13064-017-0090-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shenyue Qin
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.,Molecular and Developmental Biology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Stephanie M Ware
- Department of Pediatrics and Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Ronald R Waclaw
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.,Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Kenneth Campbell
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA. .,Neurosurgery, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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17
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Ravi N, Sanchez-Guardado L, Lois C, Kelsch W. Determination of the connectivity of newborn neurons in mammalian olfactory circuits. Cell Mol Life Sci 2017; 74:849-867. [PMID: 27695873 PMCID: PMC11107630 DOI: 10.1007/s00018-016-2367-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 08/24/2016] [Accepted: 09/13/2016] [Indexed: 12/24/2022]
Abstract
The mammalian olfactory bulb is a forebrain structure just one synapse downstream from the olfactory sensory neurons and performs the complex computations of sensory inputs. The formation of this sensory circuit is shaped through activity-dependent and cell-intrinsic mechanisms. Recent studies have revealed that cell-type specific connectivity and the organization of synapses in dendritic compartments are determined through cell-intrinsic programs already preset in progenitor cells. These progenitor programs give rise to subpopulations within a neuron type that have distinct synaptic organizations. The intrinsically determined formation of distinct synaptic organizations requires factors from contacting cells that match the cell-intrinsic programs. While certain genes control wiring within the newly generated neurons, other regulatory genes provide intercellular signals and are only expressed in neurons that will form contacts with the newly generated cells. Here, the olfactory system has provided a useful model circuit to reveal the factors regulating assembly of the highly structured connectivity in mammals.
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Affiliation(s)
- Namasivayam Ravi
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Luis Sanchez-Guardado
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA, 91125, USA
| | - Carlos Lois
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA, 91125, USA.
| | - Wolfgang Kelsch
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany.
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18
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Frazer S, Prados J, Niquille M, Cadilhac C, Markopoulos F, Gomez L, Tomasello U, Telley L, Holtmaat A, Jabaudon D, Dayer A. Transcriptomic and anatomic parcellation of 5-HT 3AR expressing cortical interneuron subtypes revealed by single-cell RNA sequencing. Nat Commun 2017; 8:14219. [PMID: 28134272 PMCID: PMC5290279 DOI: 10.1038/ncomms14219] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 12/08/2016] [Indexed: 11/09/2022] Open
Abstract
Cortical GABAergic interneurons constitute a highly diverse population of inhibitory neurons that are key regulators of cortical microcircuit function. An important and heterogeneous group of cortical interneurons specifically expresses the serotonin receptor 3A (5-HT3AR) but how this diversity emerges during development is poorly understood. Here we use single-cell transcriptomics to identify gene expression patterns operating in Htr3a-GFP+ interneurons during early steps of cortical circuit assembly. We identify three main molecular types of Htr3a-GFP+ interneurons, each displaying distinct developmental dynamics of gene expression. The transcription factor Meis2 is specifically enriched in a type of Htr3a-GFP+ interneurons largely confined to the cortical white matter. These MEIS2-expressing interneurons appear to originate from a restricted region located at the embryonic pallial–subpallial boundary. Overall, this study identifies MEIS2 as a subclass-specific marker for 5-HT3AR-containing interstitial interneurons and demonstrates that the transcriptional and anatomical parcellation of cortical interneurons is developmentally coupled. Cortical GABAergic interneurons are highly diverse in their gene expression, electrophysiological properties, and connectivity. Here the authors reveal three distinct subtypes of Htr3a-GFP+ interneurons using the single-cell RNA-seq approach, and identify MEIS2 as a marker for one such subtype.
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Affiliation(s)
- Sarah Frazer
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Julien Prados
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Mathieu Niquille
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Christelle Cadilhac
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Foivos Markopoulos
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Lucia Gomez
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Ugo Tomasello
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Ludovic Telley
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Anthony Holtmaat
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
| | - Alexandre Dayer
- Department of Psychiatry, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland.,Department of Basic Neurosciences, University of Geneva Medical School, Geneva 4 CH-1211, Switzerland
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19
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Fujiwara N, Cave JW. Partial Conservation between Mice and Humans in Olfactory Bulb Interneuron Transcription Factor Codes. Front Neurosci 2016; 10:337. [PMID: 27489533 PMCID: PMC4951497 DOI: 10.3389/fnins.2016.00337] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/04/2016] [Indexed: 11/13/2022] Open
Abstract
The mammalian main olfactory bulb (OB) has a large population of GABAergic inhibitory interneurons that contains several subtypes defined by the co-expression other neurotransmitters and calcium binding proteins. The three most commonly studied OB interneuron subtypes co-express either Calretinin, Calbindin, or Tyrosine hydroxylase (Th). Combinations of transcription factors used to specify the phenotype of progenitors are referred to as transcription factor codes, and the current understanding of transcription factor codes that specify OB inhibitory neuron phenotypes are largely based on studies in mice. The conservation of these transcription factor codes in the human OB, however, has not been investigated. The aim of this study was to establish whether transcription factor codes in OB interneurons are conserved between mice and humans. This study compared the co-expression of Foxp2, Meis2, Pax6, and Sp8 transcription factors with Calretinin, Calbindin, or Th in human and mouse OB interneurons. This analysis found strong conservation of Calretinin co-expression with Sp8 and Meis2 as well as Th co-expression with Pax6 and Meis2. This analysis also showed that selective Foxp2 co-expression with Calbindin was conserved between mice and humans, which suggests Foxp2 is a novel determinant of the OB Calbindin interneuron phenotype. Together, the findings in this study provide insight into the conservation of transcription codes for OB interneuron phenotypes between humans and mice, as well as reveal some important differences between the species. This advance in our understanding of transcription factor codes in OB interneurons provides an important complement to the codes that have been established for other regions within the mammalian central nervous system, such as the cortex and spinal cord.
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Affiliation(s)
- Nana Fujiwara
- Burke Medical Research Institute White Plains, NY, USA
| | - John W Cave
- Burke Medical Research InstituteWhite Plains, NY, USA; The Feil Family Brain and Mind Research Institute, Weill Cornell MedicineNew York, NY, USA
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20
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Bonzano S, Bovetti S, Gendusa C, Peretto P, De Marchis S. Adult Born Olfactory Bulb Dopaminergic Interneurons: Molecular Determinants and Experience-Dependent Plasticity. Front Neurosci 2016; 10:189. [PMID: 27199651 PMCID: PMC4858532 DOI: 10.3389/fnins.2016.00189] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/18/2016] [Indexed: 12/31/2022] Open
Abstract
The olfactory bulb (OB) is a highly plastic brain region involved in the early processing of olfactory information. A remarkably feature of the OB circuits in rodents is the constitutive integration of new neurons that takes place during adulthood. Newborn cells in the adult OB are mostly inhibitory interneurons belonging to chemically, morphologically and functionally heterogeneous types. Although there is general agreement that adult neurogenesis in the OB plays a key role in sensory information processing and olfaction-related plasticity, the contribution of each interneuron subtype to such functions is far to be elucidated. Here, we focus on the dopaminergic (DA) interneurons: we highlight recent findings about their morphological features and then describe the molecular factors required for the specification/differentiation and maintenance of the DA phenotype in adult born neurons. We also discuss dynamic changes of the DA interneuron population related to age, environmental stimuli and lesions, and their possible functional implications.
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Affiliation(s)
- Sara Bonzano
- Department of Life Sciences and Systems Biology, University of TurinTorino, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of TurinOrbassano, Italy
| | - Serena Bovetti
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Claudio Gendusa
- Department of Life Sciences and Systems Biology, University of Turin Torino, Italy
| | - Paolo Peretto
- Department of Life Sciences and Systems Biology, University of TurinTorino, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of TurinOrbassano, Italy
| | - Silvia De Marchis
- Department of Life Sciences and Systems Biology, University of TurinTorino, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of TurinOrbassano, Italy
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21
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Lim DA, Alvarez-Buylla A. The Adult Ventricular-Subventricular Zone (V-SVZ) and Olfactory Bulb (OB) Neurogenesis. Cold Spring Harb Perspect Biol 2016; 8:cshperspect.a018820. [PMID: 27048191 DOI: 10.1101/cshperspect.a018820] [Citation(s) in RCA: 423] [Impact Index Per Article: 52.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A large population of neural stem/precursor cells (NSCs) persists in the ventricular-subventricular zone (V-SVZ) located in the walls of the lateral brain ventricles. V-SVZ NSCs produce large numbers of neuroblasts that migrate a long distance into the olfactory bulb (OB) where they differentiate into local circuit interneurons. Here, we review a broad range of discoveries that have emerged from studies of postnatal V-SVZ neurogenesis: the identification of NSCs as a subpopulation of astroglial cells, the neurogenic lineage, new mechanisms of neuronal migration, and molecular regulators of precursor cell proliferation and migration. It has also become evident that V-SVZ NSCs are regionally heterogeneous, with NSCs located in different regions of the ventricle wall generating distinct OB interneuron subtypes. Insights into the developmental origins and molecular mechanisms that underlie the regional specification of V-SVZ NSCs have also begun to emerge. Other recent studies have revealed new cell-intrinsic molecular mechanisms that enable lifelong neurogenesis in the V-SVZ. Finally, we discuss intriguing differences between the rodent V-SVZ and the corresponding human brain region. The rapidly expanding cellular and molecular knowledge of V-SVZ NSC biology provides key insights into postnatal neural development, the origin of brain tumors, and may inform the development regenerative therapies from cultured and endogenous human neural precursors.
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Affiliation(s)
- Daniel A Lim
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF, Department of Neurological Surgery, University of California, San Francisco, California 94143
| | - Arturo Alvarez-Buylla
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF, Department of Neurological Surgery, University of California, San Francisco, California 94143
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22
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Potts MB, Siu JJ, Price JD, Salinas RD, Cho MJ, Ramos AD, Hahn J, Margeta M, Oldham MC, Lim DA. Analysis of Mll1 deficiency identifies neurogenic transcriptional modules and Brn4 as a factor for direct astrocyte-to-neuron reprogramming. Neurosurgery 2015; 75:472-82; discussion 482. [PMID: 24887289 DOI: 10.1227/neu.0000000000000452] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Mixed lineage leukemia-1 (Mll1) epigenetically regulates gene expression patterns that specify cellular identity in both embryonic development and adult stem cell populations. In the adult mouse brain, multipotent neural stem cells (NSCs) in the subventricular zone generate new neurons throughout life, and Mll1 is required for this postnatal neurogenesis but not for glial cell differentiation. Analysis of Mll1-dependent transcription may identify neurogenic genes useful for the direct reprogramming of astrocytes into neurons. OBJECTIVE To identify Mll1-dependent transcriptional modules and to determine whether genes in the neurogenic modules can be used to directly reprogram astrocytes into neurons. METHODS We performed gene coexpression module analysis on microarray data from differentiating wild-type and Mll1-deleted subventricular zone NSCs. Key developmental regulators belonging to the neurogenic modules were overexpressed in Mll1-deleted cells and cultured cortical astrocytes, and cell phenotypes were analyzed by immunocytochemistry and electrophysiology. RESULTS Transcriptional modules that correspond to neurogenesis were identified in wild-type NSCs. Modules related to astrocytes and oligodendrocytes were enriched in Mll1-deleted NSCs, consistent with their gliogenic potential. Overexpression of genes selected from the neurogenic modules enhanced the production of neurons from Mll1-deleted cells, and overexpression of Brn4 (Pou3f4) in nonneurogenic cortical astroglia induced their transdifferentiation into electrophysiologically active neurons. CONCLUSION Our results demonstrate that Mll1 is required for the expression of neurogenic but not gliogenic transcriptional modules in a multipotent NSC population and further indicate that specific Mll1-dependent genes may be useful for direct reprogramming strategies.
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Affiliation(s)
- Matthew B Potts
- *Department of Neurological Surgery, ‡The Eli and Edythe Broad Institute of Regeneration Medicine and Stem Cell Research, §Department of Pathology, and ¶Department of Neurology University of California, San Francisco, San Francisco, California; and ‖Surgical Service, San Francisco Veterans Affairs Medical Center, San Francisco, California
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23
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The Origin, Development and Molecular Diversity of Rodent Olfactory Bulb Glutamatergic Neurons Distinguished by Expression of Transcription Factor NeuroD1. PLoS One 2015; 10:e0128035. [PMID: 26030886 PMCID: PMC4451148 DOI: 10.1371/journal.pone.0128035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 04/21/2015] [Indexed: 12/12/2022] Open
Abstract
Production of olfactory bulb neurons occurs continuously in the rodent brain. Little is known, however, about cellular diversity in the glutamatergic neuron subpopulation. In the central nervous system, the basic helix-loop-helix transcription factor NeuroD1 (ND1) is commonly associated with glutamatergic neuron development. In this study, we utilized ND1 to identify the different subpopulations of olfactory bulb glutamategic neurons and their progenitors, both in the embryo and postnatally. Using knock-in mice, transgenic mice and retroviral transgene delivery, we demonstrate the existence of several different populations of glutamatergic olfactory bulb neurons, the progenitors of which are ND1+ and ND1- lineage-restricted, and are temporally and regionally separated. We show that the first olfactory bulb glutamatergic neurons produced – the mitral cells – can be divided into molecularly diverse subpopulations. Our findings illustrate the complexity of neuronal diversity in the olfactory bulb and that seemingly homogenous neuronal populations can consist of multiple subpopulations with unique molecular signatures of transcription factors and expressing neuronal subtype-specific markers.
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Bayraktar OA, Fuentealba LC, Alvarez-Buylla A, Rowitch DH. Astrocyte development and heterogeneity. Cold Spring Harb Perspect Biol 2014; 7:a020362. [PMID: 25414368 DOI: 10.1101/cshperspect.a020362] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Astrocytes have many roles within the brain parenchyma, and a subpopulation restricted to germinal niches functions as neural stem cells (NSCs) that produce various types of neuronal progeny in relation to spatiotemporal factors. A growing body of evidence supports the concept of morphological and molecular differences between astrocytes in different brain regions, which might relate to their derivation from regionally patterned radial glia. Indeed, the notion that astrocytes are molecularly and functionally heterogeneous could help explain how the central nervous system (CNS) retains embryonic positional information into adulthood. Here, we discuss recent evidence for regionally encoded functions of astrocytes in the developing and adult CNS to provide an integrated concept of the origin and possible function of astrocyte heterogeneity. We focus on the regionalization of NSCs in the ventricular-subventricular zone (V-SVZ) of the adult mammalian brain and emerging evidence for a segmental organization of astrocytes in the developing spinal cord and forebrain. We propose that astrocytes' diversity will provide fundamental clues to understand regional brain organization and function.
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Affiliation(s)
- Omer Ali Bayraktar
- Department of Pediatrics and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, San Francisco, California 94143 Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California 94143
| | - Luis C Fuentealba
- Department of Neurosurgery, Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, San Francisco, California 94143
| | - Arturo Alvarez-Buylla
- Department of Pediatrics and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, San Francisco, California 94143 Department of Neurosurgery, Eli and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, San Francisco, California 94143
| | - David H Rowitch
- Department of Pediatrics and Edythe Broad Institute for Stem Cell Research and Regeneration Medicine, University of California, San Francisco, San Francisco, California 94143 Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, California 94143
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Kahoud RJ, Elsen GE, Hevner RF, Hodge RD. Conditional ablation of Tbr2 results in abnormal development of the olfactory bulbs and subventricular zone-rostral migratory stream. Dev Dyn 2013; 243:440-50. [PMID: 24550175 DOI: 10.1002/dvdy.24090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/15/2013] [Accepted: 10/28/2013] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Development of the olfactory bulb (OB) is a complex process that requires contributions from several progenitor cell niches to generate neuronal diversity. Previous studies showed that Tbr2 is expressed during the generation of glutamatergic OB neurons in rodents. However, relatively little is known about the role of Tbr2 in the developing OB or in the subventricular zone-rostral migratory stream (SVZ-RMS) germinal niche that gives rise to many OB neurons. RESULTS Here, we use conditional gene ablation strategies to knockout Tbr2 during embryonic mouse olfactory bulb morphogenesis, as well as during perinatal and adult neurogenesis from the SVZ-RMS niche, and describe the resulting phenotypes. We find that Tbr2 is important for the generation of mitral cells in the OB, and that the olfactory bulbs themselves are hypoplastic and disorganized in Tbr2 mutant mice. Furthermore, we show that the SVZ-RMS niche is expanded and disordered following loss of Tbr2, which leads to ectopic accumulation of neuroblasts in the RMS. Lastly, we show that adult glutamatergic neurogenesis from the SVZ is impaired by loss of Tbr2. CONCLUSIONS Tbr2 is essential for proper morphogenesis of the OB and SVZ-RMS, and is important for the generation of multiple lineages of glutamatergic olfactory bulb neurons.
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Affiliation(s)
- Robert J Kahoud
- Division of Pediatric Critical Care Medicine, University of Washington and Seattle Children's Hospital, Seattle, Washington; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
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Agoston Z, Heine P, Brill MS, Grebbin BM, Hau AC, Kallenborn-Gerhardt W, Schramm J, Götz M, Schulte D. Meis2 is a Pax6 co-factor in neurogenesis and dopaminergic periglomerular fate specification in the adult olfactory bulb. Development 2013; 141:28-38. [PMID: 24284204 DOI: 10.1242/dev.097295] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Meis homeodomain transcription factors control cell proliferation, cell fate specification and differentiation in development and disease. Previous studies have largely focused on Meis contribution to the development of non-neuronal tissues. By contrast, Meis function in the brain is not well understood. Here, we provide evidence for a dual role of the Meis family protein Meis2 in adult olfactory bulb (OB) neurogenesis. Meis2 is strongly expressed in neuroblasts of the subventricular zone (SVZ) and rostral migratory stream (RMS) and in some of the OB interneurons that are continuously replaced during adult life. Targeted manipulations with retroviral vectors expressing function-blocking forms or with small interfering RNAs demonstrated that Meis activity is cell-autonomously required for the acquisition of a general neuronal fate by SVZ-derived progenitors in vivo and in vitro. Additionally, Meis2 activity in the RMS is important for the generation of dopaminergic periglomerular neurons in the OB. Chromatin immunoprecipitation identified doublecortin and tyrosine hydroxylase as direct Meis targets in newly generated neurons and the OB, respectively. Furthermore, biochemical analyses revealed a previously unrecognized complex of Meis2 with Pax6 and Dlx2, two transcription factors involved in OB neurogenesis. The full pro-neurogenic activity of Pax6 in SVZ derived neural stem and progenitor cells requires the presence of Meis. Collectively, these results show that Meis2 cooperates with Pax6 in generic neurogenesis and dopaminergic fate specification in the adult SVZ-OB system.
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Affiliation(s)
- Zsuzsa Agoston
- Institute of Neurology (Edinger Institute), J. W. Goethe University Medical School, D-60528 Frankfurt, Germany
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Díaz-Guerra E, Pignatelli J, Nieto-Estévez V, Vicario-Abejón C. Transcriptional Regulation of Olfactory Bulb Neurogenesis. Anat Rec (Hoboken) 2013; 296:1364-82. [DOI: 10.1002/ar.22733] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 11/13/2012] [Accepted: 12/08/2012] [Indexed: 12/21/2022]
Affiliation(s)
- Eva Díaz-Guerra
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC); Madrid Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, ISCIII); Madrid Spain
| | - Jaime Pignatelli
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC); Madrid Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, ISCIII); Madrid Spain
| | - Vanesa Nieto-Estévez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC); Madrid Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, ISCIII); Madrid Spain
| | - Carlos Vicario-Abejón
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC); Madrid Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED, ISCIII); Madrid Spain
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Gribaudo S, Bovetti S, Friard O, Denorme M, Oboti L, Fasolo A, De Marchis S. Transitory and activity-dependent expression of neurogranin in olfactory bulb tufted cells during mouse postnatal development. J Comp Neurol 2013; 520:3055-69. [PMID: 22592880 DOI: 10.1002/cne.23150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Neurogranin (Ng) is a brain-specific postsynaptic calmodulin-binding protein involved in synaptic activity-dependent plasticity. In the adult olfactory bulb (OB), Ng is expressed by a large population of GABAergic interneurons in the granule cell layer. We show here that, during postnatal development, Ng is also expressed by OB neurons in the superficial external plexiform layer (sEPL) and glomerular layer (GL). These Ng-positive neurons display morphological and neurochemical features of superficial and external tufted cells. Ng expression in these cells is transient during OB development: few elements express Ng at postnatal day (P) 5, increasing in number and reaching a peak at P10, then progressively decreasing. At P30, Ng is rarely detectable in these neurons. Ng expression in developing tufted cells is also modulated at the cellular level: at earlier stages, Ng labeling is distributed throughout the cell body and dendritic arborization in the GL, but, at P20, when the glomerular circuits are fully matured, Ng becomes restricted to the soma and proximal portion of tufted cell apical dendrites. We show that olfactory deprivation at early postnatal stages induces a strong increase in Ng-positive tufted cells from P10 to P20, whereas no changes have been observed following olfactory deprivation in adult mice. These findings demonstrate that Ng expression in sEPL-GL is restricted to developmental stages and indicate its activity-dependent regulation in a time window critical for glomerular circuit development, suggesting a role for Ng in maturation and dendritic remodeling of tufted cells.
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Affiliation(s)
- S Gribaudo
- Department of Life Sciences and Systems Biology, University of Turin, 10123 Turin, Italy.
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Banerjee K, Akiba Y, Baker H, Cave JW. Epigenetic control of neurotransmitter expression in olfactory bulb interneurons. Int J Dev Neurosci 2012; 31:415-23. [PMID: 23220178 DOI: 10.1016/j.ijdevneu.2012.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 11/21/2012] [Accepted: 11/22/2012] [Indexed: 12/24/2022] Open
Abstract
Defining the molecular mechanisms that underlie development and maintenance of neuronal phenotypic diversity in the CNS is a fundamental challenge in developmental neurobiology. The vast majority of olfactory bulb (OB) interneurons are GABAergic and this neurotransmitter phenotype is specified in migrating neuroblasts by transcription of either or both glutamic acid decarboxylase 1 (Gad1) and Gad2. A subset of OB interneurons also co-express dopamine, but transcriptional repression of tyrosine hydroxylase (Th) suppresses the dopaminergic phenotype until these neurons terminally differentiate. In mature OB interneurons, GABA and dopamine levels are modulated by odorant-induced synaptic activity-dependent regulation of Gad1 and Th transcription. The molecular mechanisms that specify and maintain the GABAergic and dopaminergic phenotypes in the OB are not clearly delineated. In this report, we review previous studies and present novel findings that provide insight into the contribution of epigenetic regulatory mechanisms for controlling expression of these neurotransmitter phenotypes in the OB. We show that HDAC enzymes suppress the dopaminergic phenotype in migrating neuroblasts by repressing Th transcription. In the mature interneurons, both Th and Gad1 transcription levels are modulated by synaptic activity-dependent recruitment of acetylated Histone H3 on both the Th and Gad1 proximal promoters. We also show that HDAC2 has the opposite transcriptional response to odorant-induced synaptic activity when compared to Th and Gad1. These findings suggest that HDAC2 mediates, in part, the activity-dependent chromatin remodeling of the Th and Gad1 proximal promoters in mature OB interneurons.
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Affiliation(s)
- Kasturi Banerjee
- Burke Medical Research Institute, 785 Mamaroneck Avenue, White Plains, NY 10605, United States
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Ganz J, Kaslin J, Freudenreich D, Machate A, Geffarth M, Brand M. Subdivisions of the adult zebrafish subpallium by molecular marker analysis. J Comp Neurol 2012; 520:633-55. [PMID: 21858823 DOI: 10.1002/cne.22757] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The morphology of the telencephalon displays great diversity among different vertebrate lineages. Particularly the everted telencephalon of ray-finned fishes shows a noticeably different morphology from the evaginated telencephalon of nonray-finned fishes and other vertebrates. This makes the comparison between the different parts of the telencephalon of ray-finned fishes and other vertebrates difficult. Based on neuroanatomical, neurochemical, and connectional data no consensus on the subdivisions of the adult telencephalon of ray-finned fishes and their relation to nuclei in the telencephalon of other vertebrates has been reached yet. For tetrapods, comparative expression pattern analysis of homologous developmental genes has been a successful approach to clarify homologies between different parts of the telencephalon. In the larval zebrafish, subdivisions of the subpallium have been proposed using conserved developmental gene expression. In this study, we investigate the subdivisions of the adult zebrafish telencephalon by analyzing the expression pattern of conserved molecular marker genes. We identify the boundary between the pallium and subpallium based on the complementary expression of dlx2a, dlx5a in the subpallium and tbr1, neurod in the pallium. Furthermore, combinatorial expression of Isl, nkx2.1b, lhx1b, tbr1, eomesa, emx1, emx2, and emx3 identifies striatal-like, pallidal-like, and septal-like subdivisions within the subpallium. In contrast to previous models, we propose that the striatum and pallidum are stretched along the rostrocaudal axis of the telencephalon. Further, the septal nuclei derive from both the pallium and subpallium. On this basis, we present a new model for the subdivisions of the subpallium in teleost fish.
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Affiliation(s)
- Julia Ganz
- Biotechnology Center and Center for Regenerative Therapies Dresden, Dresden University of Technology, 01307 Dresden, Germany
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Shaker T, Dennis D, Kurrasch DM, Schuurmans C. Neurog1 and Neurog2 coordinately regulate development of the olfactory system. Neural Dev 2012; 7:28. [PMID: 22906231 PMCID: PMC3444899 DOI: 10.1186/1749-8104-7-28] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 08/03/2012] [Indexed: 01/23/2023] Open
Abstract
Background Proneural genes encode basic helix–loop–helix transcription factors that specify distinct neuronal identities in different regions of the nervous system. In the embryonic telencephalon, the proneural genes Neurog1 and Neurog2 specify a dorsal regional identity and glutamatergic projection neuron phenotype in the presumptive neocortex, but their roles in cell fate specification in the olfactory bulb, which is also partly derived from dorsal telencephalic progenitors, have yet to be assessed. Given that olfactory bulb development is guided by interactions with the olfactory epithelium in the periphery, where proneural genes are also expressed, we investigated the roles of Neurog1 and Neurog2 in the coordinated development of these two olfactory structures. Results Neurog1/2 are co-expressed in olfactory bulb progenitors, while only Neurog1 is widely expressed in progenitors for olfactory sensory neurons in the olfactory epithelium. Strikingly, only a remnant of an olfactory bulb forms in Neurog1−/−;Neurog2−/− double mutants, while this structure is smaller but distinguishable in Neurog1−/− single mutants and morphologically normal in Neurog2−/− single mutants. At the cellular level, fewer glutamatergic mitral and juxtaglomerular cells differentiate in Neurog1−/−;Neurog2−/− double-mutant olfactory bulbs. Instead, ectopic olfactory bulb interneurons are derived from dorsal telencephalic lineages in Neurog1−/−;Neurog2−/− double mutants and to a lesser extent in Neurog2−/− single mutants. Conversely, cell fate specification is normal in Neurog1−/− olfactory bulbs, but aberrant patterns of cell proliferation and neuronal migration are observed in Neurog1−/− single and Neurog1−/−;Neurog2−/− double mutants, probably contributing to their altered morphologies. Finally, in Neurog1−/− and Neurog1−/−;Neurog2−/− embryos, olfactory sensory neurons in the epithelium, which normally project to the olfactory bulb to guide its morphogenesis, fail to innervate the olfactory bulb. Conclusions We have identified a cell autonomous role for Neurog1/2 in specifying the glutamatergic identity of olfactory bulb neurons. Furthermore, Neurog1 (and not Neurog2) is required to guide olfactory sensory neuron innervation of the olfactory bulb, the loss of which results in defects in olfactory bulb proliferation and tissue morphogenesis. We thus conclude that Neurog1/2 together coordinate development of the olfactory system, which depends on tissue interactions between the olfactory bulb and epithelium.
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Affiliation(s)
- Tarek Shaker
- Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada
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Filippi A, Jainok C, Driever W. Analysis of transcriptional codes for zebrafish dopaminergic neurons reveals essential functions of Arx and Isl1 in prethalamic dopaminergic neuron development. Dev Biol 2012; 369:133-49. [PMID: 22728160 DOI: 10.1016/j.ydbio.2012.06.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 05/16/2012] [Accepted: 06/12/2012] [Indexed: 11/29/2022]
Abstract
Distinct groups of dopaminergic neurons develop at defined anatomical sites in the brain to modulate function of a large diversity of local and far-ranging circuits. However, the molecular identity as judged from transcription factor expression has not been determined for all dopaminergic groups. Here, we analyze regional expression of transcription factors in the larval zebrafish brain to determine co-expression with the Tyrosine hydroxylase marker in dopaminergic neurons. We define sets of transcription factors that clearly identify each dopaminergic group. These data confirm postulated relations to dopaminergic groups defined for mammalian systems. We focus our functional analysis on prethalamic dopaminergic neurons, which co-express the transcription factors Arx and Isl1. Morpholino-based knockdown reveals that both Arx and Isl1 are strictly required for prethalamic dopaminergic neuron development and appear to act in parallel. We further show that Arx contributes to patterning in the prethalamic region, while Isl1 is required for differentiation of prethalamic dopaminergic neurons.
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Affiliation(s)
- Alida Filippi
- Developmental Biology, Institute Biology 1, University of Freiburg, Hauptstrasse 1, D-79104 Freiburg, Germany
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33
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Targeted deletion of ERK5 MAP kinase in the developing nervous system impairs development of GABAergic interneurons in the main olfactory bulb and behavioral discrimination between structurally similar odorants. J Neurosci 2012; 32:4118-32. [PMID: 22442076 DOI: 10.1523/jneurosci.6260-11.2012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ERK5 MAP kinase is highly expressed in the developing nervous system and has been implicated in promoting the survival of immature neurons in culture. However, its role in the development and function of the mammalian nervous system has not been established in vivo. Here, we report that conditional deletion of the erk5 gene in mouse neural stem cells during development reduces the number of GABAergic interneurons in the main olfactory bulb (OB). Our data suggest that this is due to a decrease in proliferation and an increase in apoptosis in the subventricular zone and rostral migratory stream of ERK5 mutant mice. Interestingly, ERK5 mutant mice have smaller OB and are impaired in odor discrimination between structurally similar odorants. We conclude that ERK5 is a novel signaling pathway regulating developmental OB neurogenesis and olfactory behavior.
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Azim K, Zweifel S, Klaus F, Yoshikawa K, Amrein I, Raineteau O. Early Decline in Progenitor Diversity in the Marmoset Lateral Ventricle. Cereb Cortex 2012; 23:922-31. [DOI: 10.1093/cercor/bhs085] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Kosaka T, Kosaka K. Further characterization of the juxtaglomerular neurons in the mouse main olfactory bulb by transcription factors, Sp8 and Tbx21. Neurosci Res 2012; 73:24-31. [PMID: 22387948 DOI: 10.1016/j.neures.2012.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 02/18/2012] [Accepted: 02/20/2012] [Indexed: 10/28/2022]
Abstract
Juxtaglomerular neurons in the mouse main olfactory bulb consist of various types of neurons, especially classified by their chemical properties such as transmitter-related molecules and calcium binding proteins. In addition several transcription factors have been revealed to characterize neuronal subpopulations. In this study we examined the immunoreactivities of two transcription factors, Sp8 and Tbx21, in the juxtaglomerular neuronal subpopulations containing calretinin, calbindin, secretagogin, tyrosine hydroxylase (TH) and nitric oxide synthase (NOS). Both Sp8 and Tbx21 immunoreactivities were so diverse in their staining intensities. Almost all calretinin and secretagogin positive neurons were relatively strongly Sp8 positive, whereas none of calbindin positive neurons were Sp8 positive. TH positive neurons were also usually Sp8 positive, although some were faintly positive. These four types of interneurons were Tbx21 negative. On the other hand large faintly NOS positive external tufted cells were occasionally Tbx21 positive but always Sp8 negative, whereas small NOS positive periglomerular cells without distinctly stained dendrites were usually Sp8 positive and Tbx21 negative. Strangely, most of strongly NOS positive periglomerular cells with distinctly stained dendritic processes were Sp8 negative and Tbx21 negative. Thus Sp8 and Tbx21 immunoreactivities further characterized juxtaglomerular neurons and, especially confirmed the heterogeneity of NOS positive juxtaglomerular neurons.
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Affiliation(s)
- Toshio Kosaka
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
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The transcription factor Sp8 is required for the production of parvalbumin-expressing interneurons in the olfactory bulb. J Neurosci 2011; 31:8450-5. [PMID: 21653849 DOI: 10.1523/jneurosci.0939-11.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Interneurons in the olfactory bulb (OB) represent a heterogeneous population, which are first produced at embryonic stages and persisting into adulthood. Using the BrdU birthdating method combined with immunostaining for several different neuronal markers, we provide the integrated temporal patterns of distinct mouse OB interneuron production from embryonic day 14 to postnatal day 365. We show that although the majority of OB interneuron subtypes continue to be generated throughout life, most subtypes show a similar "bell-like" temporal production pattern with a peak around birth. Tyrosine hydroxylase and calretinin-expressing interneurons are produced at a relatively low rate in the adult OB, while parvalbumin-expressing (PV+) interneuron production is confined to later embryonic and early postnatal stages. We also show that Dlx5/6-expressing progenitors contribute to PV+ interneurons in the OB. Interestingly, all PV+ interneurons in the external plexiform layer (EPL) express the transcription factor Sp8. Genetic ablation of Sp8 by cre/loxP-based recombination severely reduces the number of PV+ interneurons in the EPL of the OB. Our results suggest that Sp8 is required for the normal production of PV+ interneurons in the EPL of the OB. These data expand our understanding of the temporal and molecular regulation of OB interneuron neurogenesis.
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Flames N, Hobert O. Transcriptional Control of the Terminal Fate of Monoaminergic Neurons. Annu Rev Neurosci 2011; 34:153-84. [DOI: 10.1146/annurev-neuro-061010-113824] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nuria Flames
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York 10032;
- Genes & Disease Program, Center for Genomic Regulation (CRG), Barcelona, Spain E-08003;
- Present address: Instituto de Biomedicina de Valencia IBV-CSIC, E-46010 Valencia, Spain
| | - Oliver Hobert
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York 10032;
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Heng X, Breer H, Zhang X, Tang Y, Li J, Zhang S, Le W. Sall3 correlates with the expression of TH in mouse olfactory bulb. J Mol Neurosci 2011; 46:293-302. [PMID: 21701790 DOI: 10.1007/s12031-011-9563-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 05/20/2011] [Indexed: 10/18/2022]
Abstract
Sall3 is a member of a gene family with homology to the spalt gene of Drosophila melanogaster, encoding transcription factors, and acts as downstream target of hedgehog. Vertebrate homologues of spalt have been shown to be involved in development of the limbs and nervous system and several organs including the kidney and heart; mutations in the genes are implicated in several human genetic disorders. Recent studies have shown a total loss of olfactory bulb (OB) dopaminergic (DA) neurons in Sall3-null mice. We assume that tyrosine hydroxylase (TH) may be regulated by Sall3 in OB. In this study, we find that Sall3 and TH co-localize in glomerular layer (GL) of OB. Furthermore, we demonstrate a significant induction of the proximal TH promoter transcription activity by Sall3 in dual-luciferase reporter assay and a reduction of TH expression level in Sall3-deficient cell lines. Collectively, these findings support the notion that Sall3 correlates with the expression of TH in mouse OB and may have a role in OB DA neuron development by regulating TH gene expression. The results from this study may advance our understanding of the molecular pathways of OB in the DA neuron development and differentiation.
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Affiliation(s)
- Xin Heng
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Weinandy F, Ninkovic J, Götz M. Restrictions in time and space--new insights into generation of specific neuronal subtypes in the adult mammalian brain. Eur J Neurosci 2011; 33:1045-54. [PMID: 21395847 DOI: 10.1111/j.1460-9568.2011.07602.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Key questions in regard to neuronal repair strategies are which cells are best suited to regenerate specific neuronal subtypes and how much of a neuronal circuit needs to persist in order to allow its functional repair. Here we discuss recent findings in the field of adult neurogenesis, which shed new light on these questions. Neural stem cells in the adult brain generate very distinct types of neurons depending on their regional and temporal specification. Moreover, distinct brain regions differ in the mode of neuron addition in adult neurogenesis, suggesting that different brain circuits may be able to cope differently with the incorporation of new neurons. These new insights are then considered in regard to the choice of cells with the appropriate region-specific identity for repair strategies.
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Affiliation(s)
- Franziska Weinandy
- Institute of Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, 85764 München/Neuherberg, Germany
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Winpenny E, Lebel-Potter M, Fernandez ME, Brill MS, Götz M, Guillemot F, Raineteau O. Sequential generation of olfactory bulb glutamatergic neurons by Neurog2-expressing precursor cells. Neural Dev 2011; 6:12. [PMID: 21466690 PMCID: PMC3087671 DOI: 10.1186/1749-8104-6-12] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 04/05/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While the diversity and spatio-temporal origin of olfactory bulb (OB) GABAergic interneurons has been studied in detail, much less is known about the subtypes of glutamatergic OB interneurons. RESULTS We studied the temporal generation and diversity of Neurog2-positive precursor progeny using an inducible genetic fate mapping approach. We show that all subtypes of glutamatergic neurons derive from Neurog2 positive progenitors during development of the OB. Projection neurons, that is, mitral and tufted cells, are produced at early embryonic stages, while a heterogeneous population of glutamatergic juxtaglomerular neurons are generated at later embryonic as well as at perinatal stages. While most juxtaglomerular neurons express the T-Box protein Tbr2, those generated later also express Tbr1. Based on morphological features, these juxtaglomerular cells can be identified as tufted interneurons and short axon cells, respectively. Finally, targeted electroporation experiments provide evidence that while the majority of OB glutamatergic neurons are generated from intrabulbar progenitors, a small portion of them originate from extrabulbar regions at perinatal ages. CONCLUSIONS We provide the first comprehensive analysis of the temporal and spatial generation of OB glutamatergic neurons and identify distinct populations of juxtaglomerular interneurons that differ in their antigenic properties and time of origin.
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Affiliation(s)
- Eleanor Winpenny
- Cambridge Centre for Brain Repair, Robinson Way, CB2 0PY Cambridge, UK
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Wnt5a is a transcriptional target of Dlx homeogenes and promotes differentiation of interneuron progenitors in vitro and in vivo. J Neurosci 2011; 31:2675-87. [PMID: 21325536 DOI: 10.1523/jneurosci.3110-10.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During brain development, neurogenesis, migration, and differentiation of neural progenitor cells are regulated by an interplay between intrinsic genetic programs and extrinsic cues. The Dlx homeogene transcription factors have been proposed to directly control the genesis and maturation of GABAergic interneurons of the olfactory bulb (OB), subpallium, and cortex. Here we provide evidence that Dlx genes promote differentiation of olfactory interneurons via the signaling molecule Wnt5a. Dlx2 and Dlx5 interact with homeodomain binding sequences within the Wnt5a locus and activate its transcription. Exogenously provided Wnt5a promotes GABAergic differentiation in dissociated OB neurons and in organ-type brain cultures. Finally, we show that the Dlx-mutant environment is unfavorable for GABA differentiation, in vivo and in vitro. We conclude that Dlx genes favor interneuron differentiation also in a non-cell-autonomous fashion, via expression of Wnt5a.
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42
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Yamamoto K, Vernier P. The evolution of dopamine systems in chordates. Front Neuroanat 2011; 5:21. [PMID: 21483723 PMCID: PMC3070214 DOI: 10.3389/fnana.2011.00021] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 03/15/2011] [Indexed: 12/24/2022] Open
Abstract
Dopamine (DA) neurotransmission in the central nervous system (CNS) is found throughout chordates, and its emergence predates the divergence of chordates. Many of the molecular components of DA systems, such as biosynthetic enzymes, transporters, and receptors, are shared with those of other monoamine systems, suggesting the common origin of these systems. In the mammalian CNS, the DA neurotransmitter systems are diversified and serve for visual and olfactory perception, sensory–motor programming, motivation, memory, emotion, and endocrine regulations. Some of the functions are conserved among different vertebrate groups, while others are not, and this is reflected in the anatomical aspects of DA systems in the forebrain and midbrain. Recent findings concerning a second tyrosine hydroxylase gene (TH2) revealed new populations of DA-synthesizing cells, as evidenced in the periventricular hypothalamic zones of teleost fish. It is likely that the ancestor of vertebrates possessed TH2 DA-synthesizing cells, and the TH2 gene has been lost secondarily in placental mammals. All the vertebrates possess DA cells in the olfactory bulb, retina, and in the diencephalon. Midbrain DA cells are abundant in amniotes while absent in some groups, e.g., teleosts. Studies of protochordate DA cells suggest that the diencephalic DA cells were present before the divergence of the chordate lineage. In contrast, the midbrain cell populations have probably emerged in the vertebrate lineage following the development of the midbrain–hindbrain boundary. The functional flexibility of the DA systems, and the evolvability provided by duplication of the corresponding genes permitted a large diversification of these systems. These features were instrumental in the adaptation of brain functions to the very variable way of life of vertebrates.
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Affiliation(s)
- Kei Yamamoto
- Neurobiology and Development (UPR3294), Institute of Neurobiology Alfred Fessard, CNRS Gif-sur-Yvette, France
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43
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Miller AM, Maurer LR, Zou DJ, Firestein S, Greer CA. Axon fasciculation in the developing olfactory nerve. Neural Dev 2010; 5:20. [PMID: 20723208 PMCID: PMC2936880 DOI: 10.1186/1749-8104-5-20] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 08/19/2010] [Indexed: 11/10/2022] Open
Abstract
Olfactory sensory neuron (OSN) axons exit the olfactory epithelium (OE) and extend toward the olfactory bulb (OB) where they coalesce into glomeruli. Each OSN expresses only 1 of approximately 1,200 odor receptors (ORs). OSNs expressing the same OR are distributed in restricted zones of the OE. However, within a zone, the OSNs expressing a specific OR are not contiguous - distribution appears stochastic. Upon reaching the OB the OSN axons expressing the same OR reproducibly coalesce into two to three glomeruli. While ORs appear necessary for appropriate convergence of axons, a variety of adhesion associated molecules and activity-dependent mechanisms are also implicated. Recent data suggest pre-target OSN axon sorting may influence glomerular convergence. Here, using regional and OR-specific markers, we addressed the spatio-temporal properties associated with the onset of homotypic fasciculation in embryonic mice and assessed the degree to which subpopulations of axons remain segregated as they extend toward the nascent OB. We show that immediately upon crossing the basal lamina, axons uniformly turn sharply, usually at an approximately 90° angle toward the OB. Molecularly defined subpopulations of axons show evidence of spatial segregation within the nascent nerve by embryonic day 12, within 48 hours of the first OSN axons crossing the basal lamina, but at least 72 hours before synapse formation in the developing OB. Homotypic fasciculation of OSN axons expressing the same OR appears to be a hierarchical process. While regional segregation occurs in the mesenchyme, the final convergence of OR-specific subpopulations does not occur until the axons reach the inner nerve layer of the OB.
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Affiliation(s)
- Alexandra M Miller
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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44
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Bastien-Dionne PO, David LS, Parent A, Saghatelyan A. Role of sensory activity on chemospecific populations of interneurons in the adult olfactory bulb. J Comp Neurol 2010; 518:1847-61. [PMID: 20235091 DOI: 10.1002/cne.22307] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The olfactory bulb (OB) retains a remarkable capacity to renew its interneuronal populations throughout the lifespan of animals. Neuronal precursors giving rise to the bulbar interneurons are generated in the subventricular zone and have to migrate long distances before reaching the OB. In the adult OB these neuronal precursors differentiate into distinct neuronal types, including GABAergic cells located in the granule cell layer and a diverse set of neurons in the glomerular layer comprising GABAergic and dopaminergic interneurons, as well as other neuronal subtypes expressing calretinin and calbindin. While the role of sensory activity in the integration and/or survival of newly generated cells in the olfactory system is well established, very little is known about how odorant-induced activity affects fate specification of newborn cells as well as survival and fate maintenance of preexisting neuronal populations generated in adulthood. The present study demonstrates that sensory deprivation diminishes not only the number of newborn cells in the OB, but also reduces the density of granule and periglomerular cells generated before nostril occlusion. It also shows that sensory activity has an important influence on the development and expression of dopaminergic, but not GABAergic, calretinin or calbindin phenotypes. Our data reveal that odorant-induced activity is important for the survival of both newborn and preexisting OB interneurons generated at adulthood and suggests that these chemospecific populations are differentially affected by sensory deprivation.
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Abstract
A recent study proposed that differentiation of dopaminergic neurons requires a conserved "dopamine motif" (DA-motif) that functions as a binding site for ETS DNA binding domain transcription factors. In the mammalian olfactory bulb (OB), the expression of a set of five genes [including tyrosine hydroxylase (Th)] that are necessary for differentiation of dopaminergic neurons was suggested to be regulated by the ETS-domain transcription factor ER81 via the DA-motif. To investigate this putative regulatory role of ER81, expression levels of these five genes were compared in both olfactory bulbs of adult wild-type mice subjected to unilateral naris closure and the olfactory bulbs of neonatal Er81 wild-type and mutant mice. These studies found that ER81 was necessary only for Th expression and not the other cassette genes. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSA) experiments showed that ER81 bound directly to a consensus binding site/DA-motif in the rodent Th proximal promoter. However, the ER81 binding site/DA-motif in the Th proximal promoter is poorly conserved in other mammals. Both ChIP assays with canine OB tissue and EMSA experiments with the human Th proximal promoter did not detect ER81 binding to the Th DA-motif from these species. These results suggest that regulation of Th expression by the direct binding of ER81 to the Th promoter is a species-specific mechanism. These findings indicate that ER81 is not necessary for expression of the OB dopaminergic gene cassette and that the DA-motif is not involved in differentiation of the mammalian OB dopaminergic phenotype.
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Chemical characterization of Pax6-immunoreactive periglomerular neurons in the mouse olfactory bulb. Cell Mol Neurobiol 2010; 29:1081-5. [PMID: 19399607 DOI: 10.1007/s10571-009-9405-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 04/07/2009] [Indexed: 10/20/2022]
Abstract
The Pax6 transcription factor is a key element along brain development in both the visual and olfactory systems. The involvement of Pax6 in neural fate is well documented in the visual system, whereas in the olfactory system, and in particular in the olfactory bulb (OB), its expression during adulthood has only begun to be elucidated. In the OB, the modulation of primary sensory information is first performed by periglomerular cells (PG). A considerable body of information has unveiled the neurochemical heterogeneity of these neurons. Thus it is well known that Pax6 coexists with dopaminergic/GABAergic mouse PG. However, the presence of this transcription factor in other mouse PG subpopulations has not been studied. Here, we analyzed whether Pax6 is expressed in PG containing the calcium-binding proteins neurocalcin and parvalbumin, and the neuropeptide cholecystokinin. Our results show that Pax6 is not expressed by these PG subpopulations, suggesting that it is mainly restricted to GABAergic PG populations. These findings provide new data in the chemical characterization of mouse Pax6-positive PG.
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47
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Waclaw RR, Wang B, Pei Z, Ehrman LA, Campbell K. Distinct temporal requirements for the homeobox gene Gsx2 in specifying striatal and olfactory bulb neuronal fates. Neuron 2009; 63:451-65. [PMID: 19709628 DOI: 10.1016/j.neuron.2009.07.015] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 06/16/2009] [Accepted: 07/16/2009] [Indexed: 11/15/2022]
Abstract
The homeobox gene Gsx2 (formerly Gsh2) is known to be required for striatal and olfactory bulb neurogenesis; however, its specific role in the specification of these two neuronal subtypes remains unclear. To address this, we have employed a temporally regulated gain-of-function approach in transgenic mice and found that misexpression of Gsx2 at early stages of telencephalic neurogenesis favors the specification of striatal projection neuron identity over that of olfactory bulb interneurons. In contrast, delayed activation of the Gsx2 transgene until later stages exclusively promotes olfactory bulb interneuron identity. In a complementary approach, we have conditionally inactivated Gsx2 in a temporally progressive manner. Unlike germline Gsx2 mutants, which exhibit severe alterations in both striatal and olfactory bulb neurogenesis at birth, the conditional mutants exhibited defects restricted to olfactory bulb interneurons. These results demonstrate that Gsx2 specifies striatal projection neuron and olfactory bulb interneuron identity at distinct time points during telencephalic neurogenesis.
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Affiliation(s)
- Ronald R Waclaw
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
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48
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Roybon L, Deierborg T, Brundin P, Li JY. Involvement of Ngn2, Tbr and NeuroD proteins during postnatal olfactory bulb neurogenesis. Eur J Neurosci 2009; 29:232-43. [PMID: 19200230 DOI: 10.1111/j.1460-9568.2008.06595.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Postnatal neurogenesis takes place in two brain regions, the hippocampus and the subventricular zone (SVZ). The transcriptional cascade controlling hippocampal neurogenesis has been described in detail; however, the transcriptional control of olfactory bulb neurogenesis is still not well mapped. In this study, we provide insights into the molecular events controlling postnatal olfactory bulb neurogenesis. We first show the existence of diverse neural stem cell/progenitor populations along the SVZ-rostral migratory stream (RMS) axis, focusing on those expressing the basic helix-loop-helix (bHLH) transcription factor Mash1. We provide evidence that Mash1-derived progenies generate oligodendrocytic and neuronal precursors through the transient expression of the bHLH transcription factors Olig2 and neurogenin2 (Ngn2), respectively. Furthermore, we reveal that Ngn2-positive progenies express the T-box transcription factors Tbr2 and Tbr1, which are usually present during cortical and hippocampal glutamatergic neuronal differentiation. We also highlight a cell population expressing another bHLH transcription factor, neuroD1 (ND1). The ND1-positive cells are located in the SVZ-RMS axis and also co-express Tbr2, Tbr1 and neuroD2. The observations that these cells incorporate bromodeoxyuridine and express both doublecortin and polysialylated form of neural cell adhesion molecule suggest that they are newborn neurons. Finally, using an in vitro assay, we demonstrate that Ngn2 and ND1 equally and exclusively direct differentiation of Mash1-expressing precursors into calbindin-expressing and calretinin-expressing neurons, which are both neuronal subtypes normally found in the olfactory bulb. Taken together, our data illustrate that Ngn2, neuroD and Tbr transcription factors are involved in postnatal neurogenesis in the olfactory bulb.
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Affiliation(s)
- Laurent Roybon
- Neuronal Survival Unit, Department of Experimental Medical Science, Wallenberg Neuroscience Center, BMC A10, 22184 Lund, Sweden.
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49
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Haba H, Nomura T, Suto F, Osumi N. Subtype-specific reduction of olfactory bulb interneurons in Pax6 heterozygous mutant mice. Neurosci Res 2009; 65:116-21. [PMID: 19505513 DOI: 10.1016/j.neures.2009.05.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 05/26/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
Abstract
Interneurons in the olfactory bulb (OB) play essential roles in the processing of olfactory information. They are classified into several subpopulations by the expression of different neurochemical markers. Here we focused on a transcription factor Pax6, and examined its expression and function in distinct subtypes of OB interneurons. We identified Pax6 expression in specific subtypes of interneurons in the external plexiform layer (EPL). The number of these interneuron subtypes was dramatically decreased in Pax6 heterozygous mutant mice. These results indicate that Pax6 is required for differentiation and/or maintenance of EPL interneurons in the adult mouse OB.
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Affiliation(s)
- Hasumi Haba
- Division of Developmental Neuroscience, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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50
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Liu F, You Y, Li X, Ma T, Nie Y, Wei B, Li T, Lin H, Yang Z. Brain injury does not alter the intrinsic differentiation potential of adult neuroblasts. J Neurosci 2009; 29:5075-87. [PMID: 19386903 PMCID: PMC6665479 DOI: 10.1523/jneurosci.0201-09.2009] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 02/21/2009] [Accepted: 03/10/2009] [Indexed: 12/30/2022] Open
Abstract
Neuroblasts produced by the neural stem cells of the adult subventricular zone (SVZ) migrate into damaged brain areas after stroke or other brain injuries, and previous data have suggested that they generate regionally appropriate new neurons. To classify the types of neurons produced subsequent to ischemic injury, we combined BrdU or virus labeling with multiple neuronal markers to characterize new cells at different times after the induction of stroke. We show that SVZ neuroblasts give rise almost exclusively to calretinin-expressing cells in the damaged striatum, resulting in the accumulation of these cells during long term recovery after stroke. The vast majority of SVZ neuroblasts as well as newly born young and mature neurons in the damaged striatum constitutively express the transcription factor Sp8, but do not express transcription factors characteristic of medium-sized spiny neurons, the primary striatal projection neurons lost after stroke. Our results suggest that adult neuroblasts do not alter their intrinsic differentiation potential after brain injury.
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Affiliation(s)
- Fang Liu
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Yan You
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Xiaosu Li
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Tong Ma
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Yanzhen Nie
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Bin Wei
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
| | - Tiejun Li
- Department of Pharmacology, School of Pharmacy, Second Military Medical University, 200433 Shanghai, People's Republic of China, and
| | - Huanbing Lin
- Department of Pharmacology, School of Pharmaceutical Sciences, Southern Medical University, 510515 Guangzhou, People's Republic of China
| | - Zhengang Yang
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, 200032 Shanghai, People's Republic of China
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