1
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Gold MP, Ong W, Masteller AM, Ghasemi DR, Galindo JA, Park NR, Huynh NC, Donde A, Pister V, Saurez RA, Vladoiu MC, Hwang GH, Eisemann T, Donovan LK, Walker AD, Benetatos J, Dufour C, Garzia L, Segal RA, Wechsler-Reya RJ, Mesirov JP, Korshunov A, Pajtler KW, Pomeroy SL, Ayrault O, Davidson SM, Cotter JA, Taylor MD, Fraenkel E. Developmental basis of SHH medulloblastoma heterogeneity. Nat Commun 2024; 15:270. [PMID: 38191555 PMCID: PMC10774283 DOI: 10.1038/s41467-023-44300-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
Many genes that drive normal cellular development also contribute to oncogenesis. Medulloblastoma (MB) tumors likely arise from neuronal progenitors in the cerebellum, and we hypothesized that the heterogeneity observed in MBs with sonic hedgehog (SHH) activation could be due to differences in developmental pathways. To investigate this question, here we perform single-nucleus RNA sequencing on highly differentiated SHH MBs with extensively nodular histology and observed malignant cells resembling each stage of canonical granule neuron development. Through innovative computational approaches, we connect these results to published datasets and find that some established molecular subtypes of SHH MB appear arrested at different developmental stages. Additionally, using multiplexed proteomic imaging and MALDI imaging mass spectrometry, we identify distinct histological and metabolic profiles for highly differentiated tumors. Our approaches are applicable to understanding the interplay between heterogeneity and differentiation in other cancers and can provide important insights for the design of targeted therapies.
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Grants
- R35 NS122339 NINDS NIH HHS
- U01 CA253547 NCI NIH HHS
- U24 CA220341 NCI NIH HHS
- R01 NS089076 NINDS NIH HHS
- R01 CA255369 NCI NIH HHS
- P50 HD105351 NICHD NIH HHS
- R01 NS106155 NINDS NIH HHS
- R01 CA159859 NCI NIH HHS
- P30 CA014089 NCI NIH HHS
- U01 CA184898 NCI NIH HHS
- EIF | Stand Up To Cancer (SU2C)
- The Pediatric Brain Tumour Foundation, The Terry Fox Research Institute, The Canadian Institutes of Health Research, The Cure Search Foundation, Matthew Larson Foundation (IronMatt), b.r.a.i.n.child, Meagan’s Walk, SWIFTY Foundation, The Brain Tumour Charity, Genome Canada, Genome BC, Genome Quebec, the Ontario Research Fund, Worldwide Cancer Research, V-Foundation for Cancer Research, and the Ontario Institute for Cancer Research through funding provided by the Government of Ontario, Canadian Cancer Society Research Institute Impact grant, a Cancer Research UK Brain Tumour Award, and the Garron Family Chair in Childhood Cancer Research at the Hospital for Sick Children and the University of Toronto. We also thank Yoon-Jae Cho, John Michaels, Koei Chin, Joe Gray, Connie New, and Ali Abdullatif for their help with the manuscript. Additionally, we appreciate support from the USC Norris Comprehensive Cancer Center Translational Pathology Core (P30CA014089), the Pediatric Research Biorepository at CHLA, and the Histology Core at the Koch Institute at MIT.
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Affiliation(s)
- Maxwell P Gold
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Winnie Ong
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Andrew M Masteller
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - David R Ghasemi
- Hopp-Children's Cancer Center Heidelberg (KiTZ), Heidelberg, Germany
- Division of Pediatric Neuro-oncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Pediatric Oncology, Hematology, and Immunology, Heidelberg University Hospital, Heidelberg, Germany
| | - Julie Anne Galindo
- Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles (CHLA), Los Angeles, CA, USA
| | - Noel R Park
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
- Ludwig Institute for Cancer Research, Princeton University, Princeton, NJ, USA
| | - Nhan C Huynh
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Aneesh Donde
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Veronika Pister
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Raul A Saurez
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Maria C Vladoiu
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Grace H Hwang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Tanja Eisemann
- Cancer Genome and Epigenetics Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Laura K Donovan
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
| | - Adam D Walker
- Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles (CHLA), Los Angeles, CA, USA
| | - Joseph Benetatos
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Christelle Dufour
- Department of Child and Adolescent Oncology, Gustave Roussy, Villejuif, France
- INSERM U981, Molecular Predictors and New Targets in Oncology, University Paris-Saclay, Villejuif, France
| | - Livia Garzia
- Cancer Research Program, McGill University, Montreal, QC, Canada
- MUHC Research Institute, McGill University, Montreal, QC, Canada
| | - Rosalind A Segal
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Robert J Wechsler-Reya
- Cancer Genome and Epigenetics Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Jill P Mesirov
- Department of Medicine, Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - Andrey Korshunov
- Hopp-Children's Cancer Center Heidelberg (KiTZ), Heidelberg, Germany
- Clinical Cooperation Unit Neuropathology (B300), German Cancer Research Center (DKFZ), Heidelberg, Germany
- German Cancer Consortium (DKTK), Heidelberg, Germany
- Department of Neuropathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Kristian W Pajtler
- Hopp-Children's Cancer Center Heidelberg (KiTZ), Heidelberg, Germany
- Division of Pediatric Neuro-oncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Pediatric Oncology, Hematology, and Immunology, Heidelberg University Hospital, Heidelberg, Germany
| | - Scott L Pomeroy
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Olivier Ayrault
- Institut Curie, PSL Research University, CNRS UMR, INSERM, Orsay, France
- Université Paris-Saclay, CNRS UMR 3347, INSERM U1021, Orsay, France
| | - Shawn M Davidson
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Jennifer A Cotter
- Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles (CHLA), Los Angeles, CA, USA
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael D Taylor
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada
- Division of Neurosurgery, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Surgery, University of Toronto, Toronto, ON, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Texas Children's Cancer Center, Hematology-Oncology Section, Houston, TX, USA
- Department of Pediatrics - Hematology/Oncology and Neurosurgery, Baylor College of Medicine, Houston, TX, USA
| | - Ernest Fraenkel
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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2
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Sun W, Cheng H, Yang Y, Tang D, Li X, An L. Requirements of Postnatal proBDNF in the Hippocampus for Spatial Memory Consolidation and Neural Function. Front Cell Dev Biol 2021; 9:678182. [PMID: 34336832 PMCID: PMC8319730 DOI: 10.3389/fcell.2021.678182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/03/2021] [Indexed: 11/17/2022] Open
Abstract
Mature brain-derived neurotrophic factor (BDNF) and its downstream signaling pathways have been implicated in regulating postnatal development and functioning of rodent brain. However, the biological role of its precursor pro-brain-derived neurotrophic factor (proBDNF) in the postnatal brain remains unknown. The expression of hippocampal proBDNF was blocked in postnatal weeks, and multiple behavioral tests, Western blot and morphological techniques, and neural recordings were employed to investigate how proBDNF played a role in spatial cognition in adults. The peak expression and its crucial effects were found in the fourth but not in the second or eighth postnatal week. Blocking proBDNF expression disrupted spatial memory consolidation rather than learning or memory retrieval. Structurally, blocking proBDNF led to the reduction in spine density and proportion of mature spines. Although blocking proBDNF did not affect N-methyl-D-aspartate (NMDA) receptor (NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits, the learning-induced phosphorylation of the GluN2B subunit level declined significantly. Functionally, paired-pulse facilitation, post-low-frequency stimulation (LFS) transiently enhanced depression, and GluN2B-dependent short-lasting long-term depression in the Schaffer collateral-CA1 pathway were weakened. The firing rate of pyramidal neurons was significantly suppressed around the target region during the memory test. Furthermore, the activation of GluN2B-mediated signaling could effectively facilitate neural function and mitigate memory impairment. The findings were consistent with the hypothesis that postnatal proBDNF played an essential role in synaptic and cognitive functions.
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Affiliation(s)
- Wei Sun
- Behavioral Neuroscience Laboratory, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China.,Department of Pediatric, The First Affiliated Hospital, Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Hong Cheng
- Behavioral Neuroscience Laboratory, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China.,Department of Neurology, Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Yang Yang
- Department of Pediatric, The First Affiliated Hospital, Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Dongxin Tang
- Behavioral Neuroscience Laboratory, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China
| | - Xiaolian Li
- Department of Neurology, Jinan Geriatric Hospital, Jinan, China
| | - Lei An
- Behavioral Neuroscience Laboratory, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China.,Department of Pediatric, The First Affiliated Hospital, Guizhou University of Traditional Chinese Medicine, Guiyang, China.,Department of Neurology, Guizhou University of Traditional Chinese Medicine, Guiyang, China.,Department of Physiology, University of Saskatchewan, Saskatoon, SK, Canada
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3
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Wijayatunge R, Liu F, Shpargel KB, Wayne NJ, Chan U, Boua JV, Magnuson T, West AE. The histone demethylase Kdm6b regulates a mature gene expression program in differentiating cerebellar granule neurons. Mol Cell Neurosci 2017; 87:4-17. [PMID: 29254825 DOI: 10.1016/j.mcn.2017.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/21/2017] [Accepted: 11/06/2017] [Indexed: 02/09/2023] Open
Abstract
The histone H3 lysine 27 (H3K27) demethylase Kdm6b (Jmjd3) can promote cellular differentiation, however its physiological functions in neurons remain to be fully determined. We studied the expression and function of Kdm6b in differentiating granule neurons of the developing postnatal mouse cerebellum. At postnatal day 7, Kdm6b is expressed throughout the layers of the developing cerebellar cortex, but its expression is upregulated in newborn cerebellar granule neurons (CGNs). Atoh1-Cre mediated conditional knockout of Kdm6b in CGN precursors either alone or in combination with Kdm6a did not disturb the gross morphological development of the cerebellum. Furthermore, RNAi-mediated knockdown of Kdm6b in cultured CGN precursors did not alter the induced expression of early neuronal marker genes upon cell cycle exit. By contrast, knockdown of Kdm6b significantly impaired the induction of a mature neuronal gene expression program, which includes gene products required for functional synapse maturation. Loss of Kdm6b also impaired the ability of Brain-Derived Neurotrophic Factor (BDNF) to induce expression of Grin2c and Tiam1 in maturing CGNs. Taken together, these data reveal a previously unknown role for Kdm6b in the postmitotic stages of CGN maturation and suggest that Kdm6b may work, at least in part, by a transcriptional mechanism that promotes gene sensitivity to regulation by BDNF.
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Affiliation(s)
- Ranjula Wijayatunge
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Fang Liu
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Karl B Shpargel
- Dept. of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Nicole J Wayne
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Urann Chan
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Jane-Valeriane Boua
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States
| | - Terry Magnuson
- Dept. of Genetics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, United States
| | - Anne E West
- Dept. of Neurobiology, Duke University Medical Center, Durham, NC 27710, United States.
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4
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Mitre M, Mariga A, Chao MV. Neurotrophin signalling: novel insights into mechanisms and pathophysiology. Clin Sci (Lond) 2017; 131:13-23. [PMID: 27908981 PMCID: PMC5295469 DOI: 10.1042/cs20160044] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 07/18/2016] [Accepted: 08/09/2016] [Indexed: 12/29/2022]
Abstract
Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are prominent regulators of neuronal survival, growth and differentiation during development. While trophic factors are viewed as well-understood but not innovative molecules, there are many lines of evidence indicating that BDNF plays an important role in the pathophysiology of many neurodegenerative disorders, depression, anxiety and other psychiatric disorders. In particular, lower levels of BDNF are associated with the aetiology of Alzheimer's and Huntington's diseases. A major challenge is to explain how neurotrophins are able to induce plasticity, improve learning and memory and prevent age-dependent cognitive decline through receptor signalling. This article will review the mechanism of action of neurotrophins and how BDNF/tropomyosin receptor kinase B (TrkB) receptor signaling can dictate trophic responses and change brain plasticity through activity-dependent stimulation. Alternative approaches for modulating BDNF/TrkB signalling to deliver relevant clinical outcomes in neurodegenerative and neuropsychiatric disorders will also be described.
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Affiliation(s)
- Mariela Mitre
- Neuroscience and Physiology and Psychiatry, New York University School of Medicine, New York, NY 10016, U.S.A.
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, U.S.A
| | - Abigail Mariga
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, U.S.A
- Departments of Cell Biology, New York University School of Medicine, New York, NY 10016, U.S.A
| | - Moses V Chao
- Neuroscience and Physiology and Psychiatry, New York University School of Medicine, New York, NY 10016, U.S.A
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, U.S.A
- Departments of Cell Biology, New York University School of Medicine, New York, NY 10016, U.S.A
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5
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Gustafsson JR, Katsioudi G, Issazadeh-Navikas S, Kornum BR. Neurobasal media facilitates increased specificity of siRNA-mediated knockdown in primary cerebellar cultures. J Neurosci Methods 2016; 274:116-124. [PMID: 27717866 DOI: 10.1016/j.jneumeth.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/15/2016] [Accepted: 10/01/2016] [Indexed: 12/21/2022]
Abstract
BACKGROUND Efficient and specific knockdown of proteins in post-mitotic cells such as differentiated neurons can be difficult to achieve. Further, special care must be taken to maintain the health of neurons in vitro. We wanted to achieve knockdown in primary cerebellar granule neurons, which can be effectively grown in Neurobasal™ media. NEW METHOD We tested the efficiency of siRNA from the Accell range from Dharmacon™ when delivered in Neurobasal™ media in contrast to the recommended Accell Delivery media provided by the manufacturer. RESULTS We observed a more specific knockdown of target in Neurobasal™ media, than in Accell Delivery media when using cerebellar granule neurons. Transfection efficiency and cell viability was comparable between the two media. COMPARISON WITH EXISTING METHODS Delivery of siRNA in Neurobasal™ media facilitates increased specificity of the knockdown compared to delivery in Accell Delivery media. The off-target effect observed in Accell Delivery media was not a secondary biological response to downregulation of target, but rather a mixture of specific and non-specific off-target effects. CONCLUSIONS Specific knockdown of target can be achieved in primary cerebellar granule cells using Accell siRNAs in Neurobasal™ media. This method ensures specific knockdown in post-mitotic neurons without the need for biosafety level 2 laboratories, additional reagents, or instruments needed by other transfection.
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Affiliation(s)
- Julie Ry Gustafsson
- Department of Clinical Biochemistry, Molecular Sleep Laboratory, Rigshospitalet, Nordre Ringvej 57, 2600 Glostrup, Denmark.
| | - Georgia Katsioudi
- Department of Clinical Biochemistry, Molecular Sleep Laboratory, Rigshospitalet, Nordre Ringvej 57, 2600 Glostrup, Denmark.
| | - Shohreh Issazadeh-Navikas
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark.
| | - Birgitte Rahbek Kornum
- Department of Clinical Biochemistry, Molecular Sleep Laboratory, Rigshospitalet, Nordre Ringvej 57, 2600 Glostrup, Denmark; Department of Neurophysiology, Rigshospitalet, Glostrup, Denmark.
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6
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Neuroprotection Mediated through GluN2C-Containing N-methyl-D-aspartate (NMDA) Receptors Following Ischemia. Sci Rep 2016; 6:37033. [PMID: 27845401 PMCID: PMC5109474 DOI: 10.1038/srep37033] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/24/2016] [Indexed: 12/15/2022] Open
Abstract
Post-ischemic activation of NMDA receptors (NMDARs) has been linked to NMDAR subunit-specific signaling that mediates pro-survival or pro-death activity. Although extensive studies have been performed to characterize the role of GluN2A and GluN2B following ischemia, there is less understanding regarding the regulation of GluN2C. Here, we show that GluN2C expression is increased in acute hippocampal slices in response to ischemia. Strikingly, GluN2C knockout mice, following global cerebral ischemia, exhibit greater neuronal death in the CA1 area of the hippocampus and reduced spatial working memory compared to wild-type mice. Moreover, we find that GluN2C-expressing hippocampal neurons show marked resistance to NMDA-induced toxicity and reduced calcium influx. Using both in vivo and in vitro experimental models of ischemia, we demonstrate a neuroprotective role of GluN2C, suggesting a mechanism by which GluN2C is upregulated to promote neuronal survival following ischemia. These results may provide insights into development of NMDAR subunit-specific therapeutic strategies to protect neurons from excitotoxicity.
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7
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Brandalise F, Lujan R, Leone R, Lodola F, Cesaroni V, Romano C, Gerber U, Rossi P. Distinct expression patterns of inwardly rectifying potassium currents in developing cerebellar granule cells of the hemispheres and the vermis. Eur J Neurosci 2016; 43:1460-73. [DOI: 10.1111/ejn.13219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 02/14/2016] [Accepted: 02/23/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Federico Brandalise
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Rafael Lujan
- Instituto de Investigación en Discapacidades Neurológicas (IDINE); Department of Ciencias Médicas; Facultad de Medicina; Universidad Castilla-La Mancha; Albacete Spain
| | - Roberta Leone
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Francesco Lodola
- Molecular Cardiology; IRCCS Fondazione Salvatore Maugeri; Pavia Italy
| | - Valentina Cesaroni
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
| | - Chiara Romano
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
| | - Urs Gerber
- Brain Research Institute; University of Zurich; Zurich Switzerland
| | - Paola Rossi
- Department of Biology and Biotechnology; University of Pavia; via Ferrata 9 27100 Pavia Italy
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8
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Glutamatergic axon-derived BDNF controls GABAergic synaptic differentiation in the cerebellum. Sci Rep 2016; 6:20201. [PMID: 26830657 PMCID: PMC4735332 DOI: 10.1038/srep20201] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/23/2015] [Indexed: 01/05/2023] Open
Abstract
To study mechanisms that regulate the construction of inhibitory circuits, we examined the role of brain-derived neurotrophic factor (BDNF) in the assembly of GABAergic inhibitory synapses in the mouse cerebellar cortex. We show that within the cerebellum, BDNF-expressing cells are restricted to the internal granular layer (IGL), but that the BDNF protein is present within mossy fibers which originate from cells located outside of the cerebellum. In contrast to deletion of TrkB, the cognate receptor for BDNF, deletion of Bdnf from cerebellar cell bodies alone did not perturb the localization of pre- or postsynaptic constituents at the GABAergic synapses formed by Golgi cell axons on granule cell dendrites within the IGL. Instead, we found that BDNF derived from excitatory mossy fiber endings controls their differentiation. Our findings thus indicate that cerebellar BDNF is derived primarily from excitatory neurons--precerebellar nuclei/spinal cord neurons that give rise to mossy fibers--and promotes GABAergic synapse formation as a result of release from axons. Thus, within the cerebellum the preferential localization of BDNF to axons enhances the specificity through which BDNF promotes GABAergic synaptic differentiation.
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9
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Ehrlich DE, Josselyn SA. Plasticity-related genes in brain development and amygdala-dependent learning. GENES BRAIN AND BEHAVIOR 2015; 15:125-43. [PMID: 26419764 DOI: 10.1111/gbb.12255] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/12/2015] [Accepted: 09/14/2015] [Indexed: 12/31/2022]
Abstract
Learning about motivationally important stimuli involves plasticity in the amygdala, a temporal lobe structure. Amygdala-dependent learning involves a growing number of plasticity-related signaling pathways also implicated in brain development, suggesting that learning-related signaling in juveniles may simultaneously influence development. Here, we review the pleiotropic functions in nervous system development and amygdala-dependent learning of a signaling pathway that includes brain-derived neurotrophic factor (BDNF), extracellular signaling-related kinases (ERKs) and cyclic AMP-response element binding protein (CREB). Using these canonical, plasticity-related genes as an example, we discuss the intersection of learning-related and developmental plasticity in the immature amygdala, when aversive and appetitive learning may influence the developmental trajectory of amygdala function. We propose that learning-dependent activation of BDNF, ERK and CREB signaling in the immature amygdala exaggerates and accelerates neural development, promoting amygdala excitability and environmental sensitivity later in life.
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Affiliation(s)
- D E Ehrlich
- Department of Neuroscience and Physiology, Neuroscience Institute, NYU Langone Medical Center, New York, NY, USA.,Department of Otolaryngology, NYU Langone School of Medicine, New York, NY, USA
| | - S A Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, ON, Canada.,Department of Psychology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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10
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Regulation of chromatin accessibility and Zic binding at enhancers in the developing cerebellum. Nat Neurosci 2015; 18:647-56. [PMID: 25849986 PMCID: PMC4414887 DOI: 10.1038/nn.3995] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/12/2015] [Indexed: 12/26/2022]
Abstract
To identify chromatin mechanisms of neuronal differentiation, we characterized chromatin accessibility and gene expression in cerebellar granule neurons (CGNs) of the developing mouse. We used DNase-seq to map accessibility of cis-regulatory elements and RNA-seq to profile transcript abundance across postnatal stages of neuronal differentiation in vivo and in culture. We observed thousands of chromatin accessibility changes as CGNs differentiated and verified by H3K27ac ChIP-seq, reporter gene assays, and CRISPR-mediated activation that many of these regions function as neuronal enhancers. Motif discovery within differentially accessible chromatin regions suggested a novel role for the Zic family of transcription factors in CGN maturation. We confirmed the association of Zic with these elements by ChIP-seq, and demonstrated by knockdown that Zic1/2 are required to coordinate mature neuronal gene expression patterns. Together these data reveal chromatin dynamics at thousands of gene regulatory elements that facilitate gene expression patterns necessary for neuronal differentiation and function.
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11
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Mirante O, Brandalise F, Bohacek J, Mansuy IM. Distinct molecular components for thalamic- and cortical-dependent plasticity in the lateral amygdala. Front Mol Neurosci 2014; 7:62. [PMID: 25071439 PMCID: PMC4080466 DOI: 10.3389/fnmol.2014.00062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/16/2014] [Indexed: 01/05/2023] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR)-dependent long-term depression (LTD) in the lateral nucleus of the amygdala (LA) is a form of synaptic plasticity thought to be a cellular substrate for the extinction of fear memory. The LA receives converging inputs from the sensory thalamus and neocortex that are weakened following fear extinction. Combining field and patch-clamp electrophysiological recordings in mice, we show that paired-pulse low-frequency stimulation can induce a robust LTD at thalamic and cortical inputs to LA, and we identify different underlying molecular components at these pathways. We show that while LTD depends on NMDARs and activation of the protein phosphatases PP2B and PP1 at both pathways, it requires NR2B-containing NMDARs at the thalamic pathway, but NR2C/D-containing NMDARs at the cortical pathway. LTD appears to be induced post-synaptically at the thalamic input but presynaptically at the cortical input, since post-synaptic calcium chelation and NMDAR blockade prevent thalamic but not cortical LTD. These results highlight distinct molecular features of LTD in LA that may be relevant for traumatic memory and its erasure, and for pathologies such as post-traumatic stress disorder (PTSD).
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Affiliation(s)
- Osvaldo Mirante
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Federico Brandalise
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland
| | - Johannes Bohacek
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Isabelle M Mansuy
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
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12
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Cocaine-induced changes in NMDA receptor signaling. Mol Neurobiol 2014; 50:494-506. [PMID: 24445951 DOI: 10.1007/s12035-014-8636-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/02/2014] [Indexed: 01/27/2023]
Abstract
Addictive states are often thought to rely on lasting modification of signaling at relevant synapses. A long-standing theory posits that activity at N-methyl-D-aspartate receptors (NMDARs) is a critical component of long-term synaptic plasticity in many brain areas. Indeed, NMDAR signaling has been found to play a role in the etiology of addictive states, in particular, following cocaine exposure. However, no consensus is apparent with respect to the specific effects of cocaine exposure on NMDARs. Part of the difficulty lies in the fact that NMDARs interact extensively with multiple membrane proteins and intracellular signaling cascades. This allows for highly heterogeneous patterns of NMDAR regulation by cocaine in distinct brain regions and at distinct synapses. The picture is further complicated by findings that cocaine effects on NMDARs are sensitive to the behavioral history of cocaine exposure such as the mode of cocaine administration. This review provides a summary of evidence for cocaine-induced changes in NMDAR expression, cocaine-induced alterations in NMDAR function, and cocaine effects on NMDAR control of intracellular signaling cascades.
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13
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Lundgaard I, Luzhynskaya A, Stockley JH, Wang Z, Evans KA, Swire M, Volbracht K, Gautier HOB, Franklin RJM, ffrench-Constant C, Attwell D, Káradóttir RT. Neuregulin and BDNF induce a switch to NMDA receptor-dependent myelination by oligodendrocytes. PLoS Biol 2013; 11:e1001743. [PMID: 24391468 PMCID: PMC3876980 DOI: 10.1371/journal.pbio.1001743] [Citation(s) in RCA: 256] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 11/13/2013] [Indexed: 11/20/2022] Open
Abstract
Neuregulin switches oligodendrocytes between two modes of myelination: from a neuronal activity–independent mode to a myelin-increasing, neuronal activity–dependent, mechanism that involves glutamate release and NMDA receptor activation. Myelination is essential for rapid impulse conduction in the CNS, but what determines whether an individual axon becomes myelinated remains unknown. Here we show, using a myelinating coculture system, that there are two distinct modes of myelination, one that is independent of neuronal activity and glutamate release and another that depends on neuronal action potentials releasing glutamate to activate NMDA receptors on oligodendrocyte lineage cells. Neuregulin switches oligodendrocytes from the activity-independent to the activity-dependent mode of myelination by increasing NMDA receptor currents in oligodendrocyte lineage cells 6-fold. With neuregulin present myelination is accelerated and increased, and NMDA receptor block reduces myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. In vivo, we demonstrate that remyelination after white matter damage is NMDA receptor-dependent. These data resolve controversies over the signalling regulating myelination and suggest novel roles for neuregulin in schizophrenia and in remyelination after white matter damage. Myelination acts as an insulator for neurons and as such is essential for normal brain function, ensuring fast neuronal communication. Oligodendrocytes are the cells that wrap their membrane around nerve cell axons to form the myelin sheath that enables fast action potential propagation. However, what determines whether an individual axon becomes myelinated remains unknown. We show that there are two distinct modes of myelination: one that is independent of neuronal activity and the release of the neurotransmitter glutamate and another that depends on nerve cell action potentials releasing glutamate, which then activates a class of glutamate receptor (NMDA receptors) on oligodendrocyte lineage cells. We find that the protein neuregulin switches oligodendrocytes between these two modes of myelination; neuregulin increases oligodendrocyte lineage cells' sensitivity to glutamate by increasing the current flowing through their glutamate receptors. With neuregulin present, myelination is accelerated and increased. Blocking NMDA receptors reduces the amount of myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. We also demonstrate that remyelination after white matter damage (as occurs in diseases, such as spinal cord injury and multiple sclerosis) is NMDA receptor-dependent. These data help us understand the signalling that regulates myelination and suggest the possible involvement of neuregulin in schizophrenia and in remyelination after white matter damage.
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Affiliation(s)
- Iben Lundgaard
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Aryna Luzhynskaya
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - John H. Stockley
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Zhen Wang
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Kimberley A. Evans
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Matthew Swire
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Katrin Volbracht
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Hélène O. B. Gautier
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Robin J. M. Franklin
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Charles ffrench-Constant
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Ragnhildur T. Káradóttir
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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14
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Scientific Opinion on the developmental neurotoxicity potential of acetamiprid and imidacloprid. EFSA J 2013. [DOI: 10.2903/j.efsa.2013.3471] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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15
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Abstract
Intracellular calcium dynamics is critical for many functions of cerebellar granule cells (GrCs) including membrane excitability, synaptic plasticity, apoptosis, and regulation of gene transcription. Recent measurements of calcium responses in GrCs to depolarization and synaptic stimulation reveal spatial compartmentalization and heterogeneity within dendrites of these cells. However, the main determinants of local calcium dynamics in GrCs are still poorly understood. One reason is that there have been few published studies of calcium dynamics in intact GrCs in their native environment. In the absence of complete information, biophysically realistic models are useful for testing whether specific Ca(2+) handling mechanisms may account for existing experimental observations. Simulation results can be used to identify critical measurements that would discriminate between different models. In this review, we briefly describe experimental studies and phenomenological models of Ca(2+) signaling in GrC, and then discuss a particular biophysical model, with a special emphasis on an approach for obtaining information regarding the distribution of Ca(2+) handling systems under conditions of incomplete experimental data. Use of this approach suggests that Ca(2+) channels and fixed endogenous Ca(2+) buffers are highly heterogeneously distributed in GrCs. Research avenues for investigating calcium dynamics in GrCs by a combination of experimental and modeling studies are proposed.
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Affiliation(s)
- Elena È Saftenku
- Department of General Physiology of Nervous System, A. A. Bogomoletz Institute of Physiology, 4 Bogomoletz St., Kyiv 01024, Ukraine.
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16
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Gene regulation via excitation and BDNF is mediated by induction and phosphorylation of the Etv1 transcription factor in cerebellar granule cells. Proc Natl Acad Sci U S A 2012; 109:8734-9. [PMID: 22586091 DOI: 10.1073/pnas.1206418109] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In maturing postnatal cerebellar granule cells, the Etv1/Er81 transcription factor is induced by sequential activity-dependent mechanisms through stimulation of AMPA and NMDA receptors, voltage-dependent Nav1.2 Na(+) channels, and voltage-dependent Ca(2+) channels. Etv1 then up-regulates a battery of maturation genes involved in the cerebellar circuitry. In this process, BDNF is also induced and participates in the up-regulation of these maturation genes. Using cultures of granule cells, we addressed how the activity-dependent and BDNF signaling mechanisms converge on the regulation of the representative NR2C NMDA receptor and Tiam1 maturation genes. BDNF up-regulated both the NR2C and Tiam1 genes via the TrkB-Erk cascade and this up-regulation was blocked not only by inhibition of the activity-dependent signaling mechanisms but also by suppression of Etv1 expression with Etv1 siRNA. Importantly, Etv1 was selectively phosphorylated by Erk1/2 in the BDNF signaling cascade, and the inhibition of this phosphorylation abrogated the BDNF-induced up-regulation of the NR2C and Tiam1 genes. The luciferase reporter assays in combination with mutations of MEK and Etv1 indicated that the Erk-mediated, phosphorylated Etv1 interacted with the Ets motifs of the NR2C promoter sequence and that phosphorylation at both serine 94 and a cluster of threonines and a serine (Thr139, Thr143, and Ser146) of Etv1 was indispensable for the BDNF-mediated activation of the NR2C promoter activity. This study demonstrates that the NR2C and Tiam1 maturation genes are synergistically controlled by the activity-dependent induction of Etv1 and its phosphorylation by the BDNF signaling cascade.
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17
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Wada A, Kunii Y, Ikemoto K, Yang Q, Hino M, Matsumoto J, Niwa SI. Increased ratio of calcineurin immunoreactive neurons in the caudate nucleus of patients with schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2012; 37:8-14. [PMID: 22285318 DOI: 10.1016/j.pnpbp.2012.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 12/29/2011] [Accepted: 01/11/2012] [Indexed: 11/27/2022]
Abstract
Calcineurin (CaN) has been investigated extensively in numerous biochemical, behavioral, and genetic studies in schizophrenia because its function is closely related to dopamine-glutamate signal transduction, which is thought to be associated with pathophysiological changes in schizophrenia. Although evidence has suggested that dysfunction of CaN may be a risk factor for schizophrenia, there have been few reports focusing on the expression of CaN mRNA and CaN protein levels in the brains of schizophrenic patients. In addition, findings on CaN expression in postmortem brains from patients with schizophrenia have been inconsistent. Here, we conducted immunohistochemical examinations of several regions in postmortem brains, including the dorsolateral prefrontal cortex (DLPFC), hippocampus, caudate nucleus, and putamen, using specific antibodies, and compared the results from the brains of nine schizophrenic subjects to nine age- and sex-matched control subjects. There was no significant difference in the ratio of CaN immunoreactive (IR) neurons between schizophrenia and control groups in the DLPFC or hippocampus, and a significantly increased ratio of CaN-IR neurons was seen in the caudate nucleus in the brains from schizophrenia patients. As the striatum contains most of the brain dopamine, the results of the present study have critical implications and suggest that alterations in CaN signaling in the caudate contribute to the pathogenesis of schizophrenia. This is the first report of caudate CaN abnormalities in schizophrenia.
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Affiliation(s)
- Akira Wada
- Departments of Neuropsychiatry, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan
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18
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Mourlevat S, Galizzi JP, Guigal-Stéphan N, Courtade-Gaïani S, Rolland-Valognes G, Rodriguez M, Barbet F, Bourrier C, Catesson S, Chomel A, Danober L, Villain N, Caignard DH, Pirotte B, Lestage P, Lockhart BP. Molecular characterization of the AMPA-receptor potentiator S70340 in rat primary cortical culture: Whole-genome expression profiling. Neurosci Res 2011; 70:349-60. [DOI: 10.1016/j.neures.2011.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/03/2011] [Accepted: 05/09/2011] [Indexed: 10/18/2022]
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19
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The Etv1/Er81 transcription factor orchestrates activity-dependent gene regulation in the terminal maturation program of cerebellar granule cells. Proc Natl Acad Sci U S A 2011; 108:12497-502. [PMID: 21746923 DOI: 10.1073/pnas.1109940108] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the postnatal period, cerebellar granule cells express a set of the maturation gene battery in an activity-dependent manner and establish synaptic function in the cerebellar circuitry. Using primary cultures combined with specific inhibition of signaling cascades, the present investigation revealed that the expression of the maturation genes, including the NMDA glutamate receptor NR2C and GABA(A) receptor GABA(A)Rα6 genes, is controlled by strikingly unified signaling mechanisms that operate sequentially through stimulation of AMPA and NMDA receptors, Na(+) channels [voltage-gated Na channel type II (Nav1.2)], and voltage-dependent Ca(2+) channels. This signaling then induces the Ets variant gene 1 (Etv1/Er81) transcription factor of the ETS family in an activity-dependent manner. Consistent with the culture study, the ChIP assay indicated that Etv1 up-regulates the maturation genes in a developmentally regulated manner. This activation, as revealed by the luciferase assay, occurrs by interacting with the Etv1-interacting motifs present in the promoter region. Importantly, in vivo knockdown of Etv1 by DNA electroporation in the developing cerebellum prevents the up-regulation of the maturation genes but has no effects on preceding developmental processes occurring in the granule cells. Etv1 thus orchestrates the activity-dependent gene regulation in the terminal maturation program and specifies the identity of cerebellar granule cells.
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20
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Wenjin W, Wenchao L, Hao Z, Feng L, Yan W, Wodong S, Xianqun F, Wenlong D. Electrical stimulation promotes BDNF expression in spinal cord neurons through Ca(2+)- and Erk-dependent signaling pathways. Cell Mol Neurobiol 2011; 31:459-67. [PMID: 21259048 PMCID: PMC11498367 DOI: 10.1007/s10571-010-9639-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 12/09/2010] [Indexed: 01/23/2023]
Abstract
Brief electrical stimulation has been shown to be effective in promoting neuronal regeneration following peripheral nerve injury. These effects are thought to be mediated largely by the upregulation of the expression of brain-derived neurotrophic factor (BDNF) in spinal cord neurons. However, the molecular mechanisms by which electrical stimulation can promote BDNF expression are not known. The mechanism involved in BDNF expression after electrical stimulation was explored in this study. Immunohistochemistry and Western blotting were used to test BDNF expression. Confocal microscopy was utilized to study intracellular Ca(2+) volume. Immunohistochemistry and Western blotting confirmed that brief electrical stimulation increased BDNF expression in spinal cord neurons both in vivo and in vitro. Treatment of cultured neurons with nifedipine, an inhibitor of voltage-gated calcium channels, significantly reduced the BDNF increase produced by electrical stimulation, and an inhibitor of Erk completely abolished the effect of electrical stimulation. Levels of BDNF expression in the presence of the Erk inhibitor were lower that in unstimulated and untreated controls, indicating that Erk activation is required to maintain baseline levels of BDNF. Confocal microscopy using a Ca(2+)-sensitive fluorochrome revealed that electrical stimulation is accompanied by an increase in intracellular Ca(2+) levels; the increase was partly blocked by nifedipine. These findings argue that electrical stimulation increases BDNF expression in spinal cord neurons by activating a Ca(2+)- and Erk-dependent signaling pathways.
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Affiliation(s)
- Wang Wenjin
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
| | - Liu Wenchao
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
| | - Zhu Hao
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
| | - Li Feng
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
| | - Wo Yan
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
| | - Shi Wodong
- The Ophthalmology Department, Shanghai 9th People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, No. 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Fan Xianqun
- The Ophthalmology Department, Shanghai 9th People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, No. 639 Zhi Zao Ju Road, Shanghai, 200011 China
| | - Ding Wenlong
- Department of Anatomy, Shanghai Jiao Tong University, School of Medicine, No. 227, South Chongqing Road, Shanghai, 200025 China
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21
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Incontro S, Ramírez-Franco J, Sánchez-Prieto J, Torres M. Membrane depolarization regulates AMPA receptor subunit expression in cerebellar granule cells in culture. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:14-26. [PMID: 21056598 DOI: 10.1016/j.bbamcr.2010.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 10/14/2010] [Accepted: 10/27/2010] [Indexed: 11/29/2022]
Abstract
The physiological responses of AMPA receptors can be modulated through the differential expression of their subunits and by modifying their number at the cell surface. Here we have studied the expression of AMPA receptor subunits (GluR1-4) mRNAs in cerebellar granule cells grown in depolarizing (25mMK(+)) medium, and we have evaluated the effect of decreasing the [K(+)] in the culture medium for 24 h on both GluR1-4 expression (both mRNA and protein) and their presence at the plasma membrane. The expression of the four AMPAR subunits increases as the [K(+)] decreases, although the increase in GluR2 and GluR3 was only observed in the cell soma but not in the dendrites. Calcium entry through L-type calcium channel and CaMKIV activation are responsible for the reduction in the expression of AMPA receptor subunits in cells cultured in depolarizing conditions. Indeed, prolonged reduction of extracellular [K(+)] or blockage of L-type calcium channels enhanced both the surface insertion of the four AMPAR subunits and the AMPA response measured through intracellular calcium increase. These findings reveal a balanced increase in functional AMPA receptors at the surface of cells that can trigger strong increases in calcium in response to the persistent reduction of calcium entry.
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Affiliation(s)
- Salvatore Incontro
- Departamento de Bioquimica, Universidad Complutense de Madrid, Madrid, Spain
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22
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Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2711] [Impact Index Per Article: 180.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
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Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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23
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Gerber AM, Beaman-Hall CM, Mathur A, Vallano ML. Reduced blockade by extracellular Mg(2+) is permissive to NMDA receptor activation in cerebellar granule neurons that model a migratory phenotype. J Neurochem 2010; 114:191-202. [PMID: 20403073 DOI: 10.1111/j.1471-4159.2010.06746.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
NMDA receptors (NMDAR) contribute to neuronal development throughout the CNS. However, their mode(s) of activation preceding synaptic maturation is unclear, as they are not co-localized with alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors (AMPARs) which normally provide sufficient depolarization to relieve voltage-dependent blockade by Mg(2+). We used cerebellar granule neurons (CGNs) cultured at a near-physiological KCl concentration to examine maturation-dependent changes in NMDAR responses. In contrast, most studies use KCl-supplemented medium to promote survival. At 2-4 days in vitro CGNs: (i) express developmental markers resembling the in vivo migratory phenotype; (ii) maintain a basal amount of calcium responsive element-binding protein phosphorylation that requires NMDARs and calcium/calmodulin-dependent kinases, but not AMPARs; (iii) exhibit NMDA-mediated Ca(2+) influx not effectively blocked by ambient Mg(2+) (0.75 mM) or AMPARs; (iv) maintain a more depolarized resting membrane potential and increased resistance compared to synaptically-connected CGNs. Moreover, migrating CGNs in explant cultures demonstrate NMDA-mediated Ca(2+) influx not effectively blocked by 0.75 mM Mg(2+), and NMDAR but not AMPAR antagonists slow migration. These data suggest the biophysical properties of immature CGNs render NMDARs less sensitive to Mg(2+) blockade, enhancing the likelihood of activation in the absence of AMPAR depolarization.
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Affiliation(s)
- Adam M Gerber
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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24
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Akiba Y, Sasaki H, Huerta PT, Estevez AG, Baker H, Cave JW. gamma-Aminobutyric acid-mediated regulation of the activity-dependent olfactory bulb dopaminergic phenotype. J Neurosci Res 2009; 87:2211-21. [PMID: 19301430 PMCID: PMC2765820 DOI: 10.1002/jnr.22055] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
gamma-Aminobutyric acid (GABA) regulates the proliferation and migration of olfactory bulb (OB) interneuron progenitors derived from the subventricular zone (SVZ), but the role of GABA in the differentiation of these progenitors has been largely unexplored. This study examines the role of GABA in the differentiation of OB dopaminergic interneurons using neonatal forebrain organotypic slice cultures prepared from transgenic mice expressing green fluorescent protein (GFP) under the control of the tyrosine hydroxylase (Th) gene promoter (ThGFP). KCl-mediated depolarization of the slices induced ThGFP expression. The addition of GABA to the depolarized slices further increased GFP fluorescence by inducing ThGFP expression in an additional set of periglomerular cells. These findings show that GABA promoted differentiation of SVZ-derived OB dopaminergic interneurons and suggest that GABA indirectly regulated Th expression and OB dopaminergic neuron differentiation through an acceleration of the maturation rate for the dopaminergic progenitors. Additional studies revealed that the effect of GABA on ThGFP expression required activation of L- and P/Q-type Ca2+ channels as well as GABA(A) and GABA(B) receptors. These voltage-gated Ca2+ channels and GABA receptors have previously been shown to be required for the coexpressed GABAergic phenotype in the OB interneurons. Together, these findings suggest that Th expression and the differentiation of OB dopaminergic interneurons are coupled to the coexpressed GABAergic phenotype and demonstrate a novel role for GABA in neurogenesis.
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Affiliation(s)
- Yosuke Akiba
- Burke Medical Research Institute, White Plains, NY, 10605
| | - Hayato Sasaki
- Burke Medical Research Institute, White Plains, NY, 10605
| | - Patricio T. Huerta
- Burke Medical Research Institute, White Plains, NY, 10605
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, 10021
| | - Alvaro G. Estevez
- Burke Medical Research Institute, White Plains, NY, 10605
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, 10021
| | - Harriet Baker
- Burke Medical Research Institute, White Plains, NY, 10605
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, 10021
| | - John W. Cave
- Burke Medical Research Institute, White Plains, NY, 10605
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, 10021
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Activity-dependent repression of Cbln1 expression: mechanism for developmental and homeostatic regulation of synapses in the cerebellum. J Neurosci 2009; 29:5425-34. [PMID: 19403810 DOI: 10.1523/jneurosci.4473-08.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cbln1, which belongs to the C1q/tumor necrosis factor superfamily, is released from cerebellar granule cells and plays a crucial role in forming and maintaining excitatory synapses between parallel fibers (PFs; axons of granule cells) and Purkinje cells not only during development but also in the adult cerebellum. Although neuronal activity is known to cause morphological changes at synapses, how Cbln1 signaling is affected by neuronal activity remains unclear. Here, we show that chronic stimulation of neuronal activity by elevating extracellular K(+) levels or by adding kainate decreased the expression of cbln1 mRNA within several hours in mature granule cells in a manner dependent on L-type voltage-dependent Ca(2+) channels and calcineurin. Chronic activity also reduced Cbln1 protein levels within a few days, during which time the number of excitatory synapses on Purkinje cell dendrites was reduced; this activity-induced reduction of synapses was prevented by the addition of exogenous Cbln1 to the culture medium. Therefore, the activity-dependent downregulation of cbln1 may serve as a new presynaptic mechanism by which PF-Purkinje cell synapses adapt to chronically elevated activity, thereby maintaining homeostasis. In addition, the expression of cbln1 mRNA was prevented when immature granule cells were maintained in high-K(+) medium. Since immature granule cells are chronically depolarized before migrating to the internal granule layer, this depolarization-dependent regulation of cbln1 mRNA expression may also serve as a developmental switch to facilitate PF synapse formation in mature granule cells in the internal granule layer.
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26
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Role of calcineurin signaling in membrane potential-regulated maturation of cerebellar granule cells. J Neurosci 2009; 29:2938-47. [PMID: 19261889 DOI: 10.1523/jneurosci.5932-08.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
At the early postnatal period, cerebellar granule cells proliferate, differentiate, migrate, and finally form refined synaptic connections with mossy fibers. During this period, the resting membrane potential of immature granule cells is relatively depolarized, but it becomes hyperpolarized in mature cells. This investigation was conducted to examine the role of this alteration in membrane potential and its downstream signaling mechanism in development and maturation of granule cells. Experiments were designed to precisely characterize the ontogenic processes of developing granule cells by combining organotypic cerebellar cultures with the specific expression of EGFP (enhanced green fluorescent protein) in granule cells by use of DNA transfection. Multiple approaches using morphology, electrophysiology, and immunohistochemistry demonstrated that granule cells developed and matured at the physiological KCl concentration in organotypic cultures in a temporally regulated manner. We addressed how persistent membrane depolarization influences the developmental and maturation processes of granule cells by depolarizing organotypic cultures with high KCl. Depolarization preserved the developmental processes of granule cells up to the stage of formation of immature dendrites but prevented the maturation processes for synaptic formation by granule cells. Importantly, this blockade of the terminal maturation of granule cells was reversed by inactivation of calcineurin with its specific inhibitor. This investigation has demonstrated that alteration of the membrane potential and its downstream calcineurin signaling play a pivotal role in triggering the maturation program for the synaptic organization of postnatally developing granule cells.
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Nakanishi S. Genetic manipulation study of information processing in the cerebellum. Neuroscience 2009; 162:723-31. [PMID: 19344639 DOI: 10.1016/j.neuroscience.2009.01.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 01/14/2009] [Accepted: 01/14/2009] [Indexed: 10/21/2022]
Abstract
The cerebellar circuitry consists of two main excitatory glutamatergic pathways. The inputs of mossy fibers and climbing fibers converge on Purkinje cells and deep cerebellar nuclei. In this circuitry, Golgi interneurons suppress granule cell excitability via the inhibitory GABA transmitter. A novel technique termed reversible neurotransmission blocking (RNB) was genetically established, in which granule cell transmission to Purkinje cells was selectively and reversibly blocked in the mouse cerebellar circuitry. This study revealed that Purkinje cells are essential for expression of conditioned eye-blink motor learning but that this memory is acquired and stored in deep cerebellar nuclei. A different technique termed immunotoxin-mediated cell targeting (IMCT) was developed to selectively ablate Golgi cells from the mouse cerebellar network. The study disclosed that excitatory glutamate receptors and inhibitory GABA receptors cooperatively act at Golgi cell-mossy fiber-granule cell synapses and are indispensable for motor coordination and adaptation. Finally, gene targeting of mGluR2 displayed that the metabotropic glutamate receptor acts collaboratively with the ionotropic AMPA receptors at granule cell-Golgi cell synapses and is crucial for the spatiotemporal regulation in the mouse cerebellar circuitry. The neural information is thus hierarchically regulated and integrated at different levels of the cerebellar network.
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Affiliation(s)
- S Nakanishi
- Department of Systems Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan.
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Chung KF, Widdicombe J. Peripheral mechanisms II: the pharmacology of peripherally active antitussive drugs. Handb Exp Pharmacol 2009; 187:155-86. [PMID: 18825340 PMCID: PMC7122788 DOI: 10.1007/978-3-540-79842-2_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cough is an indispensable defensive reflex. Although generally beneficial, it is also a common symptom of diseases such as asthma, chronic obstructive pulmonary disease, upper respiratory tract infections, idiopathic pulmonary fibrosis and lung cancer. Cough remains a major unmet medical need and although the centrally acting opioids have remained the antitussive of choice for decades, they have many unwanted side effects. However, new research into the behaviour of airway sensory nerves has provided greater insight into the mechanisms of cough and new avenues for the discovery of novel non-opioid antitussive drugs. In this review, the pathophysiological mechanisms of cough and the development of novel antitussive drugs are reviewed.
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Affiliation(s)
- Kian Fan Chung
- National Heart & Lung Institute, Imperial College, Dovehouse Street, London, SW3 6LY UK
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Abstract
INTRODUCTIONPrimary cultures of granule neurons from the post-natal rat cerebellum provide an excellent model system for molecular and cell biological studies of neuronal development and function. The cerebellar cortex, with its highly organized structure and few neuronal subtypes, offers a well-characterized neural circuitry. Many fundamental insights into the processes of neuronal apoptosis, migration, and differentiation in the mammalian central nervous system have come from investigating granule neurons in vitro. Granule neurons are the most abundant type of neurons in the brain. In addition to the sheer volume of granule neurons, the homogeneity of the population and the fact that they can be transfected with ease render them ideal for elucidating the molecular basis of neuronal development. This protocol for isolating granule neurons from post-natal rats is relatively straightforward and quick, making use of standard enzymatic and mechanical dissociation methods. In a serum-based medium containing an inhibitor of mitosis, cerebellar granule neurons can be maintained with high purity. Axons and dendrites can be clearly distinguished on the basis of morphology and markers. For even greater versatility, this protocol for culturing granule neurons can be combined with knockout or transgenic technologies, or used in cerebellar slice overlay assays.
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Affiliation(s)
- Parizad M. Bilimoria
- Department of Pathology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Azad Bonni
- Department of Pathology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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30
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Eichler SA, Kirischuk S, Jüttner R, Schafermeier PK, Legendre P, Lehmann TN, Gloveli T, Grantyn R, Meier JC. Glycinergic tonic inhibition of hippocampal neurons with depolarizing GABAergic transmission elicits histopathological signs of temporal lobe epilepsy. J Cell Mol Med 2008; 12:2848-66. [PMID: 19210758 PMCID: PMC3828897 DOI: 10.1111/j.1582-4934.2008.00357.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Accepted: 04/17/2008] [Indexed: 01/13/2023] Open
Abstract
An increasing number of epilepsy patients are afflicted with drug-resistant temporal lobe epilepsy (TLE) and require alternative therapeutic approaches. High-affinity glycine receptors (haGlyRs) are functionally adapted to tonic inhibition due to their response to hippocampal ambient glycine, and their synthesis is activity-dependent. Therefore, in our study, we scanned TLE hippocampectomies for expression of haGlyRs and characterized the effects mediated by these receptors using primary hippocampal neurons. Increased haGlyR expression occurred in TLE hippocampi obtained from patients with a severe course of disease. Furthermore, in TLE patients, haGlyR and potassium chloride cotransporter 2 (KCC2) expressions were inversely regulated. To examine this potential causal relationship with respect to TLE histopathology, we established a hippocampal cell culture system utilising tonic inhibition mediated by haGlyRs in response to hippocam-pal ambient glycine and in the context of a high Cl equilibrium potential, as is the case in TLE hippocampal neurons. We showed that hypoactive neurons increase their ratio between glutamatergic and GABAergic synapses, reduce their dendrite length and finally undergo excitotoxicity. Pharmacological dissection of the underlying processes revealed ionotropic glutamate and TrkB receptors as critical mediators between neuronal hypoactivity and the emergence of these TLE-characteristic histopathological signs. Moreover, our results indicate a beneficial role for KCC2, because decreasing the Cl- equilibrium potential by KCC2 expression also rescued hypoactive hippocampal neurons. Thus, our data support a causal relationship between increased haGlyR expression and the emergence of histopathological TLE-characteristic signs, and they establish a pathophysiological role for neuronal hypoactivity in the context of a high Cl- equilibrium potential.
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Affiliation(s)
- Sabrina A Eichler
- RNA Editing and Hyperexcitability Disorders Helmholtz Group, Max Delbrück Center for Molecular MedicineBerlin, Germany
| | - Sergei Kirischuk
- Developmental Physiology, Institute for Neurophysiology, Charité University Medicine BerlinGermany
| | - René Jüttner
- Developmental Neurobiology, Max Delbrück Center for Molecular MedicineBerlin, Germany
| | - Philipp K Schafermeier
- RNA Editing and Hyperexcitability Disorders Helmholtz Group, Max Delbrück Center for Molecular MedicineBerlin, Germany
| | - Pascal Legendre
- UMR CNRS 7102 NPA, Université Pierre et Marie CurieParis, France
| | | | - Tengis Gloveli
- Cellular and Network Physiology, Institute of Neurophysiology, Charité University Medicine BerlinGermany
| | - Rosemarie Grantyn
- Developmental Physiology, Institute for Neurophysiology, Charité University Medicine BerlinGermany
| | - Jochen C Meier
- RNA Editing and Hyperexcitability Disorders Helmholtz Group, Max Delbrück Center for Molecular MedicineBerlin, Germany
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Dual regulation of NR2B and NR2C expression by NMDA receptor activation in mouse cerebellar granule cell cultures. Proc Natl Acad Sci U S A 2008; 105:12010-5. [PMID: 18685090 DOI: 10.1073/pnas.0805574105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the developing cerebellum, switching of the subunit composition of NMDA receptors occurs in granule cells from NR2B-containing receptors to NR2C-containing ones. We investigated the mechanisms underlying switching of NR2B and NR2C subunit composition in primary cultures of mouse granule cells at the physiological KCl concentration (5 mM). Granule cells extensively extended their neuritic processes 48 h after having been cultured in serum-free medium containing 5 mM KCl. Consistent with this morphological change, NR2B mRNA and NR2C mRNA were down- and up-regulated, respectively, in the granule cells. This dual regulation of the two mRNAs was abrogated by blocking excitation of granule cells with TTX. This neuronal activity-dependent regulation of NR2B and NR2C mRNAs was abolished by the addition of selective antagonists of AMPA receptors and NMDA receptors. Furthermore, the dual regulation of NR2B and NR2C mRNAs in TTX-treated cells was restored by the addition of NMDA in the presence of the AMPA receptor antagonist, but not by that of AMPA in the presence of the NMDA receptor antagonist. Importantly, the NMDA receptor activation drove the NR2B/NR2C switching of NMDA receptors in the cell-surface membrane of granule cells. This investigation demonstrates that stimulation of NMDA receptors in conjunction with the AMPA receptor-mediated excitation of granule cells plays a key role in functional subunit switching of NMDA receptors in maturing granule cells at the physiological KCl concentration.
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Preconditioning with NMDA protects against toxicity of 3-nitropropionic acid or glutamate in cultured cerebellar granule neurons. Neurosci Lett 2008; 440:294-8. [PMID: 18565656 DOI: 10.1016/j.neulet.2008.05.066] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 05/09/2008] [Accepted: 05/20/2008] [Indexed: 12/29/2022]
Abstract
A brief sub-lethal ischaemic stimulus has been reported to protect against subsequent ischaemic damage in vivo, and in vitro following periods of hypoxia or oxygen-glucose deprivation (OGD). Preconditioning against neurotoxic stimuli has been linked to N-methyl-d-aspartate (NMDA) receptors, since receptor blockade prevents the protection afforded by OGD, and low doses of NMDA treatment are capable of preconditioning. The current study demonstrated that NMDA preconditioning also protects against 3-nitropropionic acid (3-NPA), a generator of both excitotoxic and oxidative damage, in addition to glutamate. Cerebellar granule neuronal (CGN) cultures prepared from 8-day neonatal Sprague-Dawley rats were maintained for 8 days prior to NMDA stimulation for 6h. At 9 days in vitro (DIV), preconditioned and control cultures were subjected to a toxic insult (1 microM-10 mM glutamate or 1 microM-10 mM 3-NPA). Neuronal viability was assessed by use of a fluorescein diacetate assay. Protection was effective with 100 microM NMDA preconditioning for 6 h against 1-100 microM glutamate, and also against 1-500 microM 3-NPA. The study demonstrates that NMDA preconditioning can be beneficial against excitotoxic treatments, even when these are potentially complicated by associated oxidative damage and metabolic compromise, as is the case for 3-NPA.
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Payne HL. The role of transmembrane AMPA receptor regulatory proteins (TARPs) in neurotransmission and receptor trafficking (Review). Mol Membr Biol 2008; 25:353-62. [PMID: 18446621 DOI: 10.1080/09687680801986480] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AMPA receptors (AMPAR) mediate the majority of fast excitatory neurotransmission in the central nervous system (CNS). Transmembrane AMPAR regulatory proteins (TARPs) have been identified as a novel family of proteins which act as auxiliary subunits of AMPARs to modulate AMPAR trafficking and function. The trafficking of AMPARs to regulate the number of receptors at the synapse plays a key role in various forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Expression of the prototypical TARP, stargazin/TARPgamma2, is ablated in the stargazer mutant mouse, an animal model of absence epilepsy and cerebellar ataxia. Studies on the stargazer mutant mouse have revealed that failure to express TARPgamma2 has widespread effects on the balance of expression of both excitatory (AMPAR) and inhibitory receptors (GABA(A) receptors, GABAR). The understanding of TARP function has implications for the future development of AMPAR potentiators, which have been shown to have therapeutic potential in both psychological and neurological disorders such as schizophrenia, depression and Parkinson's disease.
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Affiliation(s)
- Helen L Payne
- Centre for Integrative Neurosciences, School of Biological and Biomedical Sciences, Durham University, Durham, UK.
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34
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Kobayashi MS, Asai S, Ishikawa K, Nishida Y, Nagata T, Takahashi Y. Global profiling of influence of intra-ischemic brain temperature on gene expression in rat brain. ACTA ACUST UNITED AC 2008; 58:171-91. [PMID: 18440647 DOI: 10.1016/j.brainresrev.2008.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2007] [Revised: 02/08/2008] [Accepted: 03/08/2008] [Indexed: 12/20/2022]
Abstract
Mild to moderate differences in brain temperature are known to greatly affect the outcome of cerebral ischemia. The impact of brain temperature on ischemic disorders has been mainly evaluated through pathological analysis. However, no comprehensive analyses have been conducted at the gene expression level. Using a high-density oligonucleotide microarray, we screened 24000 genes in the hippocampus under hypothermic (32 degrees C), normothermic (37 degrees C), and hyperthermic (39 degrees C) conditions in a rat ischemia-reperfusion model. When the ischemic group at each intra-ischemic brain temperature was compared to a sham-operated control group, genes whose expression levels changed more than three-fold with statistical significance could be detected. In our screening condition, thirty-three genes (some of them novel) were obtained after screening, and extensive functional surveys and literature reviews were subsequently performed. In the hypothermic condition, many neuroprotective factor genes were obtained, whereas cell death- and cell damage-associated genes were detected as the brain temperature increased. At all intra-ischemic brain temperatures, multiple molecular chaperone genes were obtained. The finding that intra-ischemic brain temperature affects the expression level of many genes related to neuroprotection or neurotoxicity coincides with the different pathological outcomes at different brain temperatures, demonstrating the utility of the genetic approach.
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Affiliation(s)
- Megumi Sugahara Kobayashi
- Division of Genomic Epidemiology and Clinical Trials, Advanced Medical Research Center, Nihon University School of Medicine, Oyaguchi-Kami Machi, Itabashi-ku, Tokyo 173-8610, Japan
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Payne HL, Ives JH, Sieghart W, Thompson CL. AMPA and kainate receptors mediate mutually exclusive effects on GABA(A) receptor expression in cultured mouse cerebellar granule neurones. J Neurochem 2008; 104:173-86. [PMID: 17986225 DOI: 10.1111/j.1471-4159.2007.04989.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studies on animal models of epilepsy and cerebellar ataxia, e.g., stargazer mice (stg) have identified changes in the GABAergic properties of neurones associated with the affected brain loci. Whether these changes contribute to or constitute homeostatic adaptations to a state of altered neuronal excitability is as yet unknown. Using cultured cerebellar granule neurones from control [+/+; alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR)-competent, Kainate receptor (KAR)-competent] and stg (AMPAR-incompetent, KAR-competent), we investigated whether non-NMDA receptor (NMDAR) activity regulates GABA(A) receptor (GABAR) expression. Neurones were maintained in 5 mmol/L KCl-containing basal media or depolarizing media containing either 25 mmol/L KCl or the non-NMDAR agonist kainic acid (KA) (100 micromol/L). KCl- and KA-mediated depolarization down-regulated GABAR alpha1, alpha6 and beta2, but up-regulated alpha4, beta3 and delta subunits in +/+ neurones. The KCl-evoked but not KA-evoked effects were reciprocated in stg neurones compatible with AMPAR-regulation of GABAR expression. Conversely, GABAR gamma2 expression was insensitive to KCl-mediated depolarization, but was down-regulated by KA-treatment in a 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-reversible manner in +/+ and stg neurones compatible with a KAR-mediated response. KA-mediated up-regulation of GABAR alpha4, beta3 and delta was inhibited by L-type voltage-gated calcium channel (L-VGCC) blockers and the Ca2+/calmodulin-dependent protein kinase inhibitor, 4-[(2S)-2-[(5-isoquinolinylsulfonyl)methylamino]-3-oxo-3-(4-phenyl-1-piperazinyl)propyl] phenyl isoquinoline sulfonic acid ester (KN-62). Up-regulation of GABAR alpha4 and beta3 was also prevented by calcineurin (CaN) inhibitors, FK506 and cyclosporin A. Down-regulation of GABAR alpha1, alpha6 and beta2 was independent of L-VGCC activity, but was prevented by inhibitors of CaN. Thus, we provide evidence that a KAR-mediated and at least three mutually exclusive AMPAR-mediated signalling mechanisms regulate neuronal GABAR expression.
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Affiliation(s)
- Helen L Payne
- Centre for Integrative Neurosciences, School of Biological and Biomedical Sciences, University of Durham, Durham, UK.
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36
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Payne HL, Connelly WM, Ives JH, Lehner R, Furtmuller B, Sieghart W, Tiwari P, Lucocq JM, Lees G, Thompson CL. GABAA alpha6-containing receptors are selectively compromised in cerebellar granule cells of the ataxic mouse, stargazer. J Biol Chem 2007; 282:29130-43. [PMID: 17646167 PMCID: PMC2974090 DOI: 10.1074/jbc.m700111200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stargazer mice fail to express the gamma2 isoform of transmembrane alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate (AMPA) receptor regulatory proteins that has been shown to be absolutely required for the trafficking and synaptic targeting of excitatory AMPA receptors in adult murine cerebellar granule cells. Here we show that 30 +/- 6% fewer inhibitory gamma-aminobutyric acid, type A (GABA(A)), receptors were expressed in adult stargazer cerebellum compared with controls because of a specific loss of GABA(A) receptor expression in the cerebellar granule cell layer. Radioligand binding assays allied to in situ immunogold-EM analysis and furosemide-sensitive tonic current estimates revealed that expression of the extrasynaptic (alpha6betaxdelta) alpha6-containing GABA(A) receptor were markedly and selectively reduced in stargazer. These observations were compatible with a marked reduction in expression of GABA(A) receptor alpha6, delta (mature cerebellar granule cell-specific proteins), and beta3 subunit expression in stargazer. The subunit composition of the residual alpha6-containing GABA(A) receptors was unaffected by the stargazer mutation. However, we did find evidence of an approximately 4-fold up-regulation of alpha1betadelta receptors that may compensate for the loss of alpha6-containing GABA(A) receptors. PCR analysis identified a dramatic reduction in the steady-state level of alpha6 mRNA, compatible with alpha6 being the primary target of the stargazer mutation-mediated GABA(A) receptor abnormalities. We propose that some aspects of assembly, trafficking, targeting, and/or expression of extrasynaptic alpha6-containing GABA(A) receptors in cerebellar granule cells are selectively regulated by AMPA receptor-mediated signaling.
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Affiliation(s)
- Helen L Payne
- Centre for Integrative Neurosciences, School of Biological and Biomedical Sciences, Science Research Laboratories, Durham University, South Road, Durham DH1 3LE, United Kingdom.
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Arancio O, Chao MV. Neurotrophins, synaptic plasticity and dementia. Curr Opin Neurobiol 2007; 17:325-30. [PMID: 17419049 DOI: 10.1016/j.conb.2007.03.013] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Accepted: 03/28/2007] [Indexed: 01/08/2023]
Abstract
The growing realization that neurotrophins, such as brain-derived neurotrophic factor (BDNF), are crucial in modulating synaptic plasticity has broadened the spectrum of their trophic actions. At the same time, it has become clear that Abeta peptides derived from amyloid precursor protein (APP) have dramatic effects on synaptic transmission before the onset of the neurodegenerative disease. Because neurotrophins and Abeta are responsible for affecting both synaptic and cognitive function, it is likely that their mechanisms of action will be related and might even intersect. This review highlights several recent findings that suggest trophic factors and APP use similar pathways to control neuronal activity.
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Affiliation(s)
- Ottavio Arancio
- Department of Pathology and Taub Institute, Columbia University College of Physicians and Surgeons, 630 W168th Street, New York, NY 10032, USA
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Mansuy IM, Shenolikar S. Protein serine/threonine phosphatases in neuronal plasticity and disorders of learning and memory. Trends Neurosci 2006; 29:679-86. [PMID: 17084465 DOI: 10.1016/j.tins.2006.10.004] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 07/28/2006] [Accepted: 10/19/2006] [Indexed: 01/12/2023]
Abstract
Phosphorylation and dephosphorylation of cellular proteins by protein kinases and phosphatases represent important mechanisms for controlling major biological events. In the nervous system, protein phosphatases are contained in highly dynamic complexes localized within specialized subcellular compartments and they ensure timely dephosphorylation of multiple neuronal phosphoproteins. This modulates the responsiveness of individual synapses to neural activity and controls synaptic plasticity. These enzymes in turn play a key role in many forms of learning and memory, and their dysfunction contributes to cognitive deficits associated with aging and dementias or neurodegenerative diseases. Here, we review key modes of regulation of neuronal protein serine/threonine phosphatases and their contribution to disorders of learning and memory.
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Affiliation(s)
- Isabelle M Mansuy
- Brain Research Institute, Medical Faculty of the University Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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Colley BS, Biju KC, Visegrady A, Campbell S, Fadool DA. Neurotrophin B receptor kinase increases Kv subfamily member 1.3 (Kv1.3) ion channel half-life and surface expression. Neuroscience 2006; 144:531-46. [PMID: 17101229 PMCID: PMC1884406 DOI: 10.1016/j.neuroscience.2006.09.055] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Revised: 09/21/2006] [Accepted: 09/22/2006] [Indexed: 01/29/2023]
Abstract
Kv subfamily member 1.3 (Kv1.3), a member of the Shaker family of potassium channels, has been found to play diverse roles in immunity, metabolism, insulin resistance, sensory discrimination, and axonal targeting in addition to its traditional role in the stabilization of the resting potential. We demonstrate that the neurotrophin B receptor (TrkB) causes an upregulation of Kv1.3 ion channel protein expression in the absence of the preferred ligand for the receptor (brain-derived neurotrophic factor; BDNF) and oppositely downregulates levels of Kv subfamily member 1.5. Although the effect occurs in the absence of the ligand, Kv1.3 upregulation by TrkB is dependent upon the catalytic domain of the TrkB kinase as well as tyrosine (Y) residues in the N and C terminus of the Kv1.3 channel. Using pulse-chase experiments we find that TrkB alters the half-life residence of the channel by approximately 2x and allows it to sustain activity as reflected in an increased current magnitude without alteration of kinetic properties. TrkB and Kv1.3 co-immunoprecipitate from tissue preparations of the mouse olfactory bulb and olfactory cortex, and by immunocytochemical approaches, are found to be co-localized in the glomerular, mitral cell, and internal plexiform layers of the olfactory bulb. These data suggest that Kv1.3 is not only modulated by direct phosphorylation in the presence of BDNF-activated TrkB kinase, but also may be fine tuned via regulation of surface expression while in the proximity of neurotrophic factor receptors. Given the variability of TrkB expression during development, regeneration, or neuronal activation, modulation of surface expression and turnover of Kv channels could significantly impact neuronal excitability, distinct from that of tyrosine kinase phosphorylation.
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Affiliation(s)
- B S Colley
- Department of Biological Science, Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
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Bui CJ, McGann AC, Middleton FA, Beaman-Hall CM, Vallano ML. Transcriptional profiling of depolarization-dependent phenotypic alterations in primary cultures of developing granule neurons. Brain Res 2006; 1119:13-25. [PMID: 16989786 DOI: 10.1016/j.brainres.2006.08.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 06/20/2006] [Accepted: 08/11/2006] [Indexed: 12/17/2022]
Abstract
Rat cerebellar granule neurons cultured in medium supplemented with elevated KCl are extensively used as a model to examine the coupling between neural activity and Ca(2+)-dependent gene expression. Elevated (25 mM) KCl is believed to mimic endogenous neural activity because it promotes depolarization and Ca(+2)-dependent survival and some aspects of maturation. By comparison, at least half of the granule neurons grown in standard medium containing 5 mM KCl undergo apoptosis beginning approximately 4 days in vitro. However, accumulating evidence suggests that chronic depolarization induces phenotypic abnormalities whereas growth in chemically defined medium containing 5 mM KCl more closely resembles the constitutive phenotype. To examine this, oligonucleotide microarrays and RT-PCR of selected mRNAs were used to compare transcription profiles of cultures grown in 5 mM and 25 mM KCl. In some cases, N-methyl-D-aspartate (NMDA) which, like elevated KCl, promotes long-term survival was also tested. Robust changes in several gene groups were observed and indicated that growth in elevated KCl: induces expression of mRNAs that are not normally observed; represses expression of mRNAs that should be present; maintains expression of mRNAs that are markers of immature neurons. Supplementation of the growth medium with NMDA instead of elevated KCl produces similar abnormalities. Altogether, these data indicate that growth in 5 mM KCl more closely mimics survival and maturation of granule neurons in vivo and should therefore be adopted in future studies.
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Affiliation(s)
- Cuong J Bui
- Department of Neurosurgery, SUNY, Upstate Medical University, Syracuse, NY 13210, USA
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Payne HL, Donoghue PS, Connelly WMK, Hinterreiter S, Tiwari P, Ives JH, Hann V, Sieghart W, Lees G, Thompson CL. Aberrant GABA(A) receptor expression in the dentate gyrus of the epileptic mutant mouse stargazer. J Neurosci 2006; 26:8600-8. [PMID: 16914686 PMCID: PMC2974089 DOI: 10.1523/jneurosci.1088-06.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 06/15/2006] [Accepted: 07/06/2006] [Indexed: 11/21/2022] Open
Abstract
Stargazer (stg) mutant mice fail to express stargazin [transmembrane AMPA receptor regulatory protein gamma2 (TARPgamma2)] and consequently experience absence seizure-like thalamocortical spike-wave discharges that pervade the hippocampal formation via the dentate gyrus (DG). As in other seizure models, the dentate granule cells of stg develop elaborate reentrant axon collaterals and transiently overexpress brain-derived neurotrophic factor. We investigated whether GABAergic parameters were affected by the stg mutation in this brain region. GABA(A) receptor (GABAR) alpha4 and beta3 subunits were consistently upregulated, GABAR delta expression appeared to be variably reduced, whereas GABAR alpha1, beta2, and gamma2 subunits and the GABAR synaptic anchoring protein gephyrin were essentially unaffected. We established that the alpha4 betagamma2 subunit-containing, flunitrazepam-insensitive subtype of GABARs, not normally a significant GABAR in DG neurons, was strongly upregulated in stg DG, apparently arising at the expense of extrasynaptic alpha4 betadelta-containing receptors. This change was associated with a reduction in neurosteroid-sensitive GABAR-mediated tonic current. This switch in GABAR subtypes was not reciprocated in the tottering mouse model of absence epilepsy implicating a unique, intrinsic adaptation of GABAergic networks in stg. Contrary to previous reports that suggested that TARPgamma2 is expressed in the dentate, we find that TARPgamma2 was neither detected in stg nor control DG. We report that TARPgamma8 is the principal TARP isoform found in the DG and that its expression is compromised by the stargazer mutation. These effects on GABAergic parameters and TARPgamma8 expression are likely to arise as a consequence of failed expression of TARPgamma2 elsewhere in the brain, resulting in hyperexcitable inputs to the dentate.
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Nakanishi S, Okazawa M. Membrane potential-regulated Ca2+ signalling in development and maturation of mammalian cerebellar granule cells. J Physiol 2006; 575:389-95. [PMID: 16793900 PMCID: PMC1819456 DOI: 10.1113/jphysiol.2006.113340] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
In many developing neuronal cell types, the resting membrane potential is relatively depolarized, then gradually hyperpolarizes during the early postnatal period. The regulatory roles of membrane potential changes in neuronal development and maturation have been extensively studied in developing cerebellar granule cells, using primary culture under depolarizing and non-depolarizing conditions in combination with in vivo analysis. Depolarization enhances calcium entry via voltage-sensitive Ca2+ channels (VSCCs) and activates Ca2+-calmodulin-dependent protein kinase (CaMK) and calcineurin phophatase (CaN). The activation of CaN induces many genes encoding extracellular and intracellular signalling molecules implicated in granule cell development. The inactivation of CaN in turn up-regulates many other genes characteristic of mature granule cells, including NR2C NMDA receptor and GABAAalpha1 and alpha6 receptors. The induction of NR2C also requires CaMK-up-regulated brain-derived neurotrophic factor (BDNF), indicating a convergence of signalling mechanism of the CaMK and CaN cascades. The inactivation of CaN maintains the phosphorylated and sumoylated form of a transcriptional myocyte enhances factor 2A (MEF2A) regulator. This form of MEF2A acts as a transcriptional repressor and is essential for the dendritic morphogenesis of differentiated granule cells. Collectively, the membrane potential change and the resulting Ca2+ signalling play a pivotal role in development and maturation of neuronal cells.
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Chen BS, Braud S, Badger JD, Isaac JTR, Roche KW. Regulation of NR1/NR2C N-Methyl-D-aspartate (NMDA) Receptors by Phosphorylation*. J Biol Chem 2006; 281:16583-90. [PMID: 16606616 DOI: 10.1074/jbc.m513029200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NR2C-containing N-methyl-D-aspartate (NMDA) receptors are highly expressed in cerebellar granule cells where they mediate the majority of current in the adult. NMDA receptors composed of NR1/NR2C exhibit a low conductance and reduced sensitivity to Mg(2+), compared with the more commonly studied NR2A- and NR2B-containing receptors. Despite these interesting features, very little is known about the regulation of NR2C function. Here we investigate the role of phosphorylation of NR2C in regulating NMDA receptor trafficking and ion channel properties. We identify a phosphorylation site, serine 1244 (Ser(1244)), near the extreme COOH terminus of NR2C, which is phosphorylated by both cAMP-dependent protein kinase and protein kinase C. This residue is located adjacent to the consensus PDZ ligand, a region that regulates protein-protein interactions and receptor trafficking in NR2A and NR2B. We show that Ser(1244) on NR2C is phosphorylated in vitro, in heterologous cells, and in neurons. Moreover, we demonstrate for the first time that NR2C interacts with the PSD-95 family of PDZ domain-containing proteins but that phosphorylation of Ser(1244) does not influence this PDZ interaction. Furthermore, Ser(1244) phosphorylation does not regulate surface expression of NR1/NR2C receptors. However, we find that this site does regulate the kinetics of the ion channel: a phosphomimetic mutation at Ser(1244) accelerates both the rise and decay of NMDA-evoked currents in excised patches from HEK-293 cells. Therefore, phosphorylation of Ser(1244) does not regulate trafficking but unexpectedly affects ion channel function, suggesting that phosphorylation of Ser(1244) on NR2C may be important in defining the functional properties of NMDA receptor-mediated currents in the cerebellum.
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Affiliation(s)
- Bo-Shiun Chen
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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Sato M, Suzuki K, Nakanishi S. Expression profile of BDNF-responsive genes during cerebellar granule cell development. Biochem Biophys Res Commun 2006; 341:304-9. [PMID: 16426579 DOI: 10.1016/j.bbrc.2005.12.184] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 12/22/2005] [Indexed: 01/19/2023]
Abstract
With the aid of microarray and PCR analysis, this investigation sought expression profiles of BDNF-regulated genes in cultured mouse cerebellar granule cells and addressed their relevance to gene regulation in developing granule cells in vivo. Many of the BDNF-upregulated and downregulated genes identified were upregulated and downregulated, respectively, during cerebellar development. This developmental change was, at least partly, prevented in the TrkB receptor-deficient cerebellum. The BDNF-upregulated genes were distributed in either postmigratory or both premigratory and postmigratory granule cells at postnatal day 8 (P8) and were still present in mature granule cells at P21. In contrast, the BDNF-downregulated genes were predominantly expressed in premigratory granule cells at P8 and disappeared at P21. Furthermore, many of the BDNF-upregulated gene products are implicated in signaling cascades of N-methyl-D-aspartate receptors and MAP kinase. The results indicate that BDNF signaling plays a pivotal role in promoting gene expression in granule cell development and maturation.
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Affiliation(s)
- Masaaki Sato
- Department of Molecular and Systems Biology, Graduate School of Biostudies, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
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