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Lenz M, Eichler A, Kruse P, Galanis C, Kleidonas D, Andrieux G, Boerries M, Jedlicka P, Müller U, Deller T, Vlachos A. The Amyloid Precursor Protein Regulates Synaptic Transmission at Medial Perforant Path Synapses. J Neurosci 2023; 43:5290-5304. [PMID: 37369586 PMCID: PMC10359033 DOI: 10.1523/jneurosci.1824-22.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 05/20/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
The perforant path provides the primary cortical excitatory input to the hippocampus. Because of its important role in information processing and coding, entorhinal projections to the dentate gyrus have been studied in considerable detail. Nevertheless, synaptic transmission between individual connected pairs of entorhinal stellate cells and dentate granule cells remains to be characterized. Here, we have used mouse organotypic entorhino-hippocampal tissue cultures of either sex, in which the entorhinal cortex (EC) to dentate granule cell (GC; EC-GC) projection is present, and EC-GC pairs can be studied using whole-cell patch-clamp recordings. By using cultures of wild-type mice, the properties of EC-GC synapses formed by afferents from the lateral and medial entorhinal cortex were compared, and differences in short-term plasticity were identified. As the perforant path is severely affected in Alzheimer's disease, we used tissue cultures of amyloid precursor protein (APP)-deficient mice to examine the role of APP at this synapse. APP deficiency altered excitatory neurotransmission at medial perforant path synapses, which was accompanied by transcriptomic and ultrastructural changes. Moreover, presynaptic but not postsynaptic APP deletion through the local injection of Cre-expressing adeno-associated viruses in conditional APPflox/flox tissue cultures increased the neurotransmission efficacy at perforant path synapses. In summary, these data suggest a physiological role for presynaptic APP at medial perforant path synapses that may be adversely affected under altered APP processing conditions.SIGNIFICANCE STATEMENT The hippocampus receives input from the entorhinal cortex via the perforant path. These projections to hippocampal dentate granule cells are of utmost importance for learning and memory formation. Although there is detailed knowledge about perforant path projections, the functional synaptic properties at the level of individual connected pairs of neurons are not well understood. In this study, we investigated the role of APP in mediating functional properties and transmission rules in individually connected neurons using paired whole-cell patch-clamp recordings and genetic tools in organotypic tissue cultures. Our results show that presynaptic APP expression limits excitatory neurotransmission via the perforant path, which could be compromised in pathologic conditions such as Alzheimer's disease.
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Affiliation(s)
- Maximilian Lenz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Hannover Medical School, Institute of Neuroanatomy and Cell Biology, 30625 Hannover, Germany
| | - Amelie Eichler
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Pia Kruse
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Christos Galanis
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Dimitrios Kleidonas
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Geoffroy Andrieux
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Melanie Boerries
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- German Cancer Consortium, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Peter Jedlicka
- Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus-Liebig-University, 35392 Giessen, Germany
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
| | - Ulrike Müller
- Institute of Pharmacy and Molecular Biotechnology, Functional Genomics, Ruprecht-Karls University Heidelberg, 69120 Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Center for Basics in Neuromodulation, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Center BrainLinks-BrainTools, University of Freiburg, 79104 Freiburg, Germany
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Muellerleile J, Vnencak M, Sethi MVA, Jungenitz T, Schwarzacher SW, Jedlicka P. Increased Network Inhibition in the Dentate Gyrus of Adult Neuroligin-4 Knock-Out Mice. eNeuro 2023; 10:10/4/ENEURO.0471-22.2023. [PMID: 37080762 PMCID: PMC10121080 DOI: 10.1523/eneuro.0471-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/01/2023] [Accepted: 03/12/2023] [Indexed: 04/22/2023] Open
Abstract
Loss-of-function mutations in neuroligin-4 (Nlgn4), a member of the neuroligin family of postsynaptic adhesion proteins, cause autism spectrum disorder in humans. Nlgn4 knockout (KO) in mice leads to social behavior deficits and complex alterations of synaptic inhibition or excitation, depending on the brain region. In the present work, we comprehensively analyzed synaptic function and plasticity at the cellular and network levels in hippocampal dentate gyrus of Nlgn4 KO mice. Compared with wild-type littermates, adult Nlgn4 KO mice exhibited increased paired-pulse inhibition of dentate granule cell population spikes, but no impairments in excitatory synaptic transmission or short-term and long-term plasticity in vivo In vitro patch-clamp recordings in neonatal organotypic entorhino-hippocampal slice cultures from Nlgn4 KO and wild-type littermates revealed no significant differences in excitatory or inhibitory synaptic transmission, homeostatic synaptic plasticity, and passive electrotonic properties in dentate granule cells, suggesting that the increased inhibition in vivo is the result of altered network activity in the adult Nlgn4 KO. A comparison with prior studies on Nlgn 1-3 knock-out mice reveals that each of the four neuroligins exerts a characteristic effect on both intrinsic cellular and network activity in the dentate gyrus in vivo.
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Affiliation(s)
- Julia Muellerleile
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
- Faculty of Biosciences, Goethe University Frankfurt, 60439 Frankfurt am Main, Germany
| | - Matej Vnencak
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Mohammad Valeed Ahmed Sethi
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Tassilo Jungenitz
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
- Faculty of Medicine, Justus-Liebig-University Giessen, 35392 Giessen, Germany
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A Network Model Reveals That the Experimentally Observed Switch of the Granule Cell Phenotype During Epilepsy Can Maintain the Pattern Separation Function of the Dentate Gyrus. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/978-3-319-99103-0_23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Synaptic Plasticity and Excitation-Inhibition Balance in the Dentate Gyrus: Insights from In Vivo Recordings in Neuroligin-1, Neuroligin-2, and Collybistin Knockouts. Neural Plast 2018; 2018:6015753. [PMID: 29670649 PMCID: PMC5835277 DOI: 10.1155/2018/6015753] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 12/02/2017] [Accepted: 12/11/2017] [Indexed: 01/29/2023] Open
Abstract
The hippocampal dentate gyrus plays a role in spatial learning and memory and is thought to encode differences between similar environments. The integrity of excitatory and inhibitory transmission and a fine balance between them is essential for efficient processing of information. Therefore, identification and functional characterization of crucial molecular players at excitatory and inhibitory inputs is critical for understanding the dentate gyrus function. In this minireview, we discuss recent studies unraveling molecular mechanisms of excitatory/inhibitory synaptic transmission, long-term synaptic plasticity, and dentate granule cell excitability in the hippocampus of live animals. We focus on the role of three major postsynaptic proteins localized at excitatory (neuroligin-1) and inhibitory synapses (neuroligin-2 and collybistin). In vivo recordings of field potentials have the advantage of characterizing the effects of the loss of these proteins on the input-output function of granule cells embedded in a network with intact connectivity. The lack of neuroligin-1 leads to deficient synaptic plasticity and reduced excitation but normal granule cell output, suggesting unaltered excitation-inhibition ratio. In contrast, the lack of neuroligin-2 and collybistin reduces inhibition resulting in a shift towards excitation of the dentate circuitry.
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5
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Beining M, Mongiat LA, Schwarzacher SW, Cuntz H, Jedlicka P. T2N as a new tool for robust electrophysiological modeling demonstrated for mature and adult-born dentate granule cells. eLife 2017; 6:e26517. [PMID: 29165247 PMCID: PMC5737656 DOI: 10.7554/elife.26517] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 11/21/2017] [Indexed: 12/18/2022] Open
Abstract
Compartmental models are the theoretical tool of choice for understanding single neuron computations. However, many models are incomplete, built ad hoc and require tuning for each novel condition rendering them of limited usability. Here, we present T2N, a powerful interface to control NEURON with Matlab and TREES toolbox, which supports generating models stable over a broad range of reconstructed and synthetic morphologies. We illustrate this for a novel, highly detailed active model of dentate granule cells (GCs) replicating a wide palette of experiments from various labs. By implementing known differences in ion channel composition and morphology, our model reproduces data from mouse or rat, mature or adult-born GCs as well as pharmacological interventions and epileptic conditions. This work sets a new benchmark for detailed compartmental modeling. T2N is suitable for creating robust models useful for large-scale networks that could lead to novel predictions. We discuss possible T2N application in degeneracy studies.
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Affiliation(s)
- Marcel Beining
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck SocietyFrankfurtGermany
- Frankfurt Institute for Advanced StudiesFrankfurtGermany
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe UniversityFrankfurtGermany
- Faculty of BiosciencesGoethe UniversityFrankfurtGermany
| | - Lucas Alberto Mongiat
- Instituto de Investigación en Biodiversidad y MedioambienteUniversidad Nacional del Comahue-CONICETSan Carlos de BarilocheArgentina
| | | | - Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck SocietyFrankfurtGermany
- Frankfurt Institute for Advanced StudiesFrankfurtGermany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe UniversityFrankfurtGermany
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6
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Bezaire MJ, Raikov I, Burk K, Vyas D, Soltesz I. Interneuronal mechanisms of hippocampal theta oscillations in a full-scale model of the rodent CA1 circuit. eLife 2016; 5:e18566. [PMID: 28009257 DOI: 10.7554/elife.18566.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 12/15/2016] [Indexed: 05/25/2023] Open
Abstract
The hippocampal theta rhythm plays important roles in information processing; however, the mechanisms of its generation are not well understood. We developed a data-driven, supercomputer-based, full-scale (1:1) model of the rodent CA1 area and studied its interneurons during theta oscillations. Theta rhythm with phase-locked gamma oscillations and phase-preferential discharges of distinct interneuronal types spontaneously emerged from the isolated CA1 circuit without rhythmic inputs. Perturbation experiments identified parvalbumin-expressing interneurons and neurogliaform cells, as well as interneuronal diversity itself, as important factors in theta generation. These simulations reveal new insights into the spatiotemporal organization of the CA1 circuit during theta oscillations.
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Affiliation(s)
- Marianne J Bezaire
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Ivan Raikov
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
- Department of Neurosurgery, Stanford University, Stanford, United States
| | - Kelly Burk
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Dhrumil Vyas
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, United States
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7
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Bezaire MJ, Raikov I, Burk K, Vyas D, Soltesz I. Interneuronal mechanisms of hippocampal theta oscillations in a full-scale model of the rodent CA1 circuit. eLife 2016; 5. [PMID: 28009257 PMCID: PMC5313080 DOI: 10.7554/elife.18566] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 12/15/2016] [Indexed: 12/16/2022] Open
Abstract
The hippocampal theta rhythm plays important roles in information processing; however, the mechanisms of its generation are not well understood. We developed a data-driven, supercomputer-based, full-scale (1:1) model of the rodent CA1 area and studied its interneurons during theta oscillations. Theta rhythm with phase-locked gamma oscillations and phase-preferential discharges of distinct interneuronal types spontaneously emerged from the isolated CA1 circuit without rhythmic inputs. Perturbation experiments identified parvalbumin-expressing interneurons and neurogliaform cells, as well as interneuronal diversity itself, as important factors in theta generation. These simulations reveal new insights into the spatiotemporal organization of the CA1 circuit during theta oscillations. DOI:http://dx.doi.org/10.7554/eLife.18566.001
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Affiliation(s)
- Marianne J Bezaire
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Ivan Raikov
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States.,Department of Neurosurgery, Stanford University, Stanford, United States
| | - Kelly Burk
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Dhrumil Vyas
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, United States
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8
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O'Sullivan GA, Jedlicka P, Chen HX, Kalbouneh H, Ippolito A, Deller T, Nawrotzki RA, Kuhse J, Kalaidzidis YL, Kirsch J, Schwarzacher SW, Betz H. Forebrain-specific loss of synaptic GABAA receptors results in altered neuronal excitability and synaptic plasticity in mice. Mol Cell Neurosci 2016; 72:101-13. [PMID: 26829712 DOI: 10.1016/j.mcn.2016.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 11/16/2015] [Accepted: 01/25/2016] [Indexed: 10/22/2022] Open
Abstract
Mutations that result in the defective trafficking of γ2 subunit containing GABAA receptors (γ2-GABAARs) are known to reduce synaptic inhibition. Whether perturbed clustering of non-mutated GABAARs similarly reduces synaptic inhibition in vivo is less clear. In this study we provide evidence that the loss of postsynaptic γ2-GABAARs upon postnatal ablation of gephyrin, the major scaffolding protein of inhibitory postsynapses, from mature principal neurons within the forebrain results in reduced induction of long-term potentiation (LTP) and impaired network excitability within the hippocampal dentate gyrus. The preferential reduction in not only synaptic γ2-GABAAR cluster number at dendritic sites but also the decrease in γ2-GABAAR density within individual clusters at dendritic inhibitory synapses suggests that distal synapses are more sensitive to the loss of gephyrin expression than proximal synapses. The fact that these mice display behavioural features of anxiety and epilepsy emphasises the importance of postsynaptic γ2-GABAAR clustering for synaptic inhibition.
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Affiliation(s)
- Gregory A O'Sullivan
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60318 Frankfurt/Main, Germany; Max-Planck-Institute of Cell Biology & Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, 60590 Frankfurt/Main, Germany
| | - Hong-Xing Chen
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60318 Frankfurt/Main, Germany
| | - Heba Kalbouneh
- Institute of Anatomy & Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Angelo Ippolito
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, 60590 Frankfurt/Main, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, 60590 Frankfurt/Main, Germany
| | - Ralph A Nawrotzki
- Institute of Anatomy & Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Jochen Kuhse
- Institute of Anatomy & Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Yannis L Kalaidzidis
- Max-Planck-Institute of Cell Biology & Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Joachim Kirsch
- Institute of Anatomy & Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, 60590 Frankfurt/Main, Germany
| | - Heinrich Betz
- Department of Neurochemistry, Max-Planck-Institute for Brain Research, Deutschordenstrasse 46, 60318 Frankfurt/Main, Germany
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9
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Kim YJ, Kang TC. The role of TRPC6 in seizure susceptibility and seizure-related neuronal damage in the rat dentate gyrus. Neuroscience 2015; 307:215-30. [PMID: 26327362 DOI: 10.1016/j.neuroscience.2015.08.054] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/18/2015] [Accepted: 08/22/2015] [Indexed: 11/29/2022]
Abstract
Transient receptor potential canonical channel-6 (TRPC6) forms Ca(2+)-permeable non-selective cation channels in neurons. Although TRPC6 plays an important role in neurite outgrowth and neuronal survival during development, TRPC6 expression profiles available to identify distinctive hippocampal neuronal damage and hippocampal excitability in epilepsy are less defined. As compared to normal animals, TRPC6 expression was down-regulated in chronic epileptic rats showing spontaneous recurrent seizures. TRPC6 knockdown increased seizure susceptibility, excitability ratio and paired-pulse inhibition in the dentate gyrus (DG) of normal animals. Furthermore, TRPC6 knockdown promoted programmed neuronal necrosis in dentate granule cells, but prevented it in CA1 and CA3 neurons following status epilepticus. The present data suggest for the first time that TRPC6 may inhibit seizure susceptibility and neuronal vulnerability in the rat DG.
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Affiliation(s)
- Y-J Kim
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chunchon 200-702, South Korea
| | - T-C Kang
- Department of Anatomy and Neurobiology, Institute of Epilepsy Research, College of Medicine, Hallym University, Chunchon 200-702, South Korea.
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Tejada J, Roque AC. Computational models of dentate gyrus with epilepsy-induced morphological alterations in granule cells. Epilepsy Behav 2014; 38:63-70. [PMID: 24613760 DOI: 10.1016/j.yebeh.2014.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/05/2014] [Accepted: 02/05/2014] [Indexed: 01/24/2023]
Abstract
Temporal lobe epilepsy provokes a number of different morphological alterations in granule cells of the hippocampus dentate gyrus. These alterations may be associated with the hyperactivity and hypersynchrony found in the epileptic dentate gyrus, and their study requires the use of different kinds of approaches including computational modeling. Conductance-based models of both normal and epilepsy-induced morphologically altered granule cells have been used in the construction of network models of dentate gyrus to study the effects of these alterations on epilepsy. Here, we review these models and discuss their contributions to the understanding of the association between alterations in neuronal morphology and epilepsy in the dentate gyrus.
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Affiliation(s)
- Julian Tejada
- Departamento de Física, FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, SP 14040-901, Brazil; Departamento de Psicologia, DPS, Universidade Federal de Sergipe, SE 49100-000, Brazil.
| | - Antonio C Roque
- Departamento de Física, FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, SP 14040-901, Brazil
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Sanchez-Mut JV, Aso E, Panayotis N, Lott I, Dierssen M, Rabano A, Urdinguio RG, Fernandez AF, Astudillo A, Martin-Subero JI, Balint B, Fraga MF, Gomez A, Gurnot C, Roux JC, Avila J, Hensch TK, Ferrer I, Esteller M. DNA methylation map of mouse and human brain identifies target genes in Alzheimer's disease. ACTA ACUST UNITED AC 2013; 136:3018-27. [PMID: 24030951 PMCID: PMC3784285 DOI: 10.1093/brain/awt237] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The central nervous system has a pattern of gene expression that is closely regulated with respect to functional and anatomical regions. DNA methylation is a major regulator of transcriptional activity, and aberrations in the distribution of this epigenetic mark may be involved in many neurological disorders, such as Alzheimer’s disease. Herein, we have analysed 12 distinct mouse brain regions according to their CpG 5’-end gene methylation patterns and observed their unique epigenetic landscapes. The DNA methylomes obtained from the cerebral cortex were used to identify aberrant DNA methylation changes that occurred in two mouse models of Alzheimer’s disease. We were able to translate these findings to patients with Alzheimer’s disease, identifying DNA methylation-associated silencing of three targets genes: thromboxane A2 receptor (TBXA2R), sorbin and SH3 domain containing 3 (SORBS3) and spectrin beta 4 (SPTBN4). These hypermethylation targets indicate that the cyclic AMP response element-binding protein (CREB) activation pathway and the axon initial segment could contribute to the disease.
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Affiliation(s)
- Jose V Sanchez-Mut
- 1 Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
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12
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Xiao M, Bosch MK, Nerbonne JM, Ornitz DM. FGF14 localization and organization of the axon initial segment. Mol Cell Neurosci 2013; 56:393-403. [PMID: 23891806 DOI: 10.1016/j.mcn.2013.07.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 06/26/2013] [Accepted: 07/21/2013] [Indexed: 01/26/2023] Open
Abstract
The axon initial segment (AIS) is highly enriched in the structural proteins ankyrin G and βIV-spectrin, the pore-forming (α) subunits of voltage-gated sodium (Nav) channels, and functional Nav channels, and is critical for the initiation of action potentials. We previously reported that FGF14, a member of the intracellular FGF (iFGF) sub-family, is expressed in cerebellar Purkinje neurons and that the targeted inactivation of Fgf14 in mice (Fgf14(-/-)) results in markedly reduced Purkinje neuron excitability. Here, we demonstrate that FGF14 immunoreactivity is high in the AIS of Purkinje neurons and is distributed in a decreasing, proximal to distal, gradient. This pattern is evident early in the postnatal development of Purkinje neurons and is also observed in many other types of central neurons. In (Scn8a(med)) mice, which are deficient in expression of the Nav1.6 α subunit, FGF14 immunoreactivity is markedly increased and expanded in the Purkinje neuron AIS, in parallel with increased expression of the Nav1.1 (Scn1a) α subunit and expanded expression of βIV-spectrin. Although Nav1.1, FGF14, and βIV-spectrin are affected, ankyrin G immunoreactivity at the AIS of Scn8a(med) and wild type (WT) Purkinje neurons was not significantly different. In Fgf14(-/-) Purkinje neurons, βIV-spectrin and ankyrin G immunoreactivity at the AIS were also similar to WT Purkinje neurons, although both the Nav1.1 and Nav1.6 α subunits are modestly, but significantly (p<0.005), reduced within sub-domains of the AIS, changes that may contribute to the reduced excitability of Fgf14(-/-) Purkinje neurons.
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Affiliation(s)
- Maolei Xiao
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Kähne T, Kolodziej A, Smalla KH, Eisenschmidt E, Haus UU, Weismantel R, Kropf S, Wetzel W, Ohl FW, Tischmeyer W, Naumann M, Gundelfinger ED. Synaptic proteome changes in mouse brain regions upon auditory discrimination learning. Proteomics 2012; 12:2433-44. [PMID: 22696468 PMCID: PMC3509369 DOI: 10.1002/pmic.201100669] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Changes in synaptic efficacy underlying learning and memory processes are assumed to be associated with alterations of the protein composition of synapses. Here, we performed a quantitative proteomic screen to monitor changes in the synaptic proteome of four brain areas (auditory cortex, frontal cortex, hippocampus striatum) during auditory learning. Mice were trained in a shuttle box GO/NO-GO paradigm to discriminate between rising and falling frequency modulated tones to avoid mild electric foot shock. Control-treated mice received corresponding numbers of either the tones or the foot shocks. Six hours and 24 h later, the composition of a fraction enriched in synaptic cytomatrix-associated proteins was compared to that obtained from naïve mice by quantitative mass spectrometry. In the synaptic protein fraction obtained from trained mice, the average percentage (±SEM) of downregulated proteins (59.9 ± 0.5%) exceeded that of upregulated proteins (23.5 ± 0.8%) in the brain regions studied. This effect was significantly smaller in foot shock (42.7 ± 0.6% down, 40.7 ± 1.0% up) and tone controls (43.9 ± 1.0% down, 39.7 ± 0.9% up). These data suggest that learning processes initially induce removal and/or degradation of proteins from presynaptic and postsynaptic cytoskeletal matrices before these structures can acquire a new, postlearning organisation. In silico analysis points to a general role of insulin-like signalling in this process.
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Affiliation(s)
- Thilo Kähne
- Institute of Experimental Internal Medicine, Medical School, Otto von Guericke University, Magdeburg, Germany
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Schneider CJ, Bezaire M, Soltesz I. Toward a full-scale computational model of the rat dentate gyrus. Front Neural Circuits 2012; 6:83. [PMID: 23162433 PMCID: PMC3499761 DOI: 10.3389/fncir.2012.00083] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 10/27/2012] [Indexed: 11/13/2022] Open
Abstract
Recent advances in parallel computing, including the creation of the parallel version of the NEURON simulation environment, have allowed for a previously unattainable level of complexity and detail in neural network models. Previously, we published a functional NEURON model of the rat dentate gyrus with over 50,000 biophysically realistic, multicompartmental neurons, but network simulations could only utilize a single processor. By converting the model to take advantage of parallel NEURON, we are now able to utilize greater computational resources and are able to simulate the full-scale dentate gyrus, containing over a million neurons. This has eliminated the previous necessity for scaling adjustments and allowed for a more direct comparison to experimental techniques and results. The translation to parallel computing has provided a superlinear speedup of computation time and dramatically increased the overall computer memory available to the model. The incorporation of additional computational resources has allowed for more detail and elements to be included in the model, bringing the model closer to a more complete and accurate representation of the biological dentate gyrus. As an example of a major step toward an increasingly accurate representation of the biological dentate gyrus, we discuss the incorporation of realistic granule cell dendrites into the model. Our previous model contained simplified, two-dimensional dendritic morphologies that were identical for neurons of the same class. Using the software tools L-Neuron and L-Measure, we are able to introduce cell-to-cell variability by generating detailed, three-dimensional granule cell morphologies that are based on biological reconstructions. Through these and other improvements, we aim to construct a more complete full-scale model of the rat dentate gyrus, to provide a better tool to delineate the functional role of cell types within the dentate gyrus and their pathological changes observed in epilepsy.
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Affiliation(s)
- Calvin J Schneider
- Department of Anatomy and Neurobiology, University of California Irvine Irvine, CA, USA
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Abstract
With the rapid rise in our knowledge about the structural and functional properties of neuronal microcircuits and the exponentially increasing power of computers, it has become possible to closely integrate experimental findings with large-scale, anatomically and biophysically realistic computational simulations of control and epileptic neuronal networks with unprecedented precision and predictive power. In this paper, we discuss the biological basis of model development, and outline specific applications, including exciting new computational and experimental results concerning the roles of aberrant hyperconnected hub-like neurons in seizures.
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Affiliation(s)
- Marianne Case
- Anatomy & Neurobiology, University of California-Irvine, CA 92697, USA.
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Functional consequences of the lack of amyloid precursor protein in the mouse dentate gyrus in vivo. Exp Brain Res 2011; 217:441-7. [PMID: 22076403 DOI: 10.1007/s00221-011-2911-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 10/07/2011] [Indexed: 01/15/2023]
Abstract
The amyloid precursor protein (APP) plays a crucial role in the pathogenesis of Alzheimer's disease. Here, we studied whether the lack of APP affects the synaptic properties in the dentate gyrus by measuring granule cell field potentials evoked by perforant path stimulation in anesthetized 9-11-month-old APP-deficient mice in vivo. We found decreased paired-pulse facilitation, indicating altered presynaptic short-term plasticity in the APP-deficient dentate gyrus. In contrast, excitatory synaptic strength and granule cell firing were unchanged in APP knockout mice. Likewise, long-term potentiation (LTP) induced by a theta-burst stimulation protocol was not impaired in the absence of APP. These findings suggest that the deletion of APP may affect presynaptic plasticity of synaptic transmission at the perforant path-granule cell synapse but leaves synaptic efficacy intact and LTP preserved, possibly due to functional redundancy within the APP gene family.
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Devaux JJ. The C-terminal domain of ßIV-spectrin is crucial for KCNQ2 aggregation and excitability at nodes of Ranvier. J Physiol 2010; 588:4719-30. [PMID: 20962009 DOI: 10.1113/jphysiol.2010.196022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The spectrin cytoskeleton has an important function in the targeting of proteins to excitable membrane domains. In axons, βIV-spectrin stabilizes voltage-gated sodium (Nav) channel clusters at nodes of Ranvier and axon initial segments, two regions crucial for the generation and conduction of action potentials. Here, I investigated the physiology of the neuromuscular junction and peripheral nerves in quivering-3J mice, which show a frame-shift base insertion in the Spnb4 gene and lack the C-terminus of βIV-spectrin. The quivering-3J mice show prominent spontaneous and evoked hyperactivities at diaphragm neuromuscular junctions. These neuromyotonic and myokymic discharges were more prominent in adult animals when tremors and ataxia were pronounced. Recordings of sciatic and phrenic nerves showed that the hyperactivities originate in myelinated axons distally from nerve terminals. Axon and myelin structure in the PNS were unaffected in quivering-3J mice. Of interest, KCNQ2 subunit aggregates were undetectable at PNS and CNS nodes, whereas Nav and Kv1.1/Kv1.2 channels were properly concentrated at nodal and juxtaparanodal regions, respectively. The protein level of KCNQ2 subunits was normal in mutant animals, suggesting that KCNQ2 subunit absence stems from clustering or trafficking defects in axons. The quivering-3J nodes also presented high densities of ankyrin-G and CK2α, two cytosolic molecules involved with aggregating Nav and KCNQ2/3 channels in axons. Because βIV-spectrin does not interact with KCNQ2/3 subunits, it is suspected that βIV-spectrin regulates the distribution of KCNQ2/3 subunits in axonal subdomains via regulatory partners. Retigabine, an activator of KCNQ2/3 channels, attenuated the repetitive activities in quivering-3J mice, suggesting that depletion of KCNQ2 subunits at nodes initiates neuromyotonic/myokymic discharges. These findings demonstrate that spectrin cytoskeleton finely regulates ion channel distribution and implicates KCNQ2/3 subunits in axonal excitability and in myokymia aetiology.
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Affiliation(s)
- Jérôme J Devaux
- Département Signalisation Neuronale, CRN2M, UMR 6231, CNRS, Faculté de Médecine - Secteur Nord, Université de la Méditerranée-Université Paul Cézanne, CS80011, Bd Pierre Dramard, 13344 Marseille Cedex 15, France.
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Jedlicka P, Hoon M, Papadopoulos T, Vlachos A, Winkels R, Poulopoulos A, Betz H, Deller T, Brose N, Varoqueaux F, Schwarzacher SW. Increased Dentate Gyrus Excitability in Neuroligin-2-Deficient Mice in Vivo. Cereb Cortex 2010; 21:357-67. [DOI: 10.1093/cercor/bhq100] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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Wimmer VC, Reid CA, So EYW, Berkovic SF, Petrou S. Axon initial segment dysfunction in epilepsy. J Physiol 2010; 588:1829-40. [PMID: 20375142 DOI: 10.1113/jphysiol.2010.188417] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The axon initial segment (AIS) contains the site of action potential initiation and plays a major role in neuronal excitability. AIS function relies on high concentrations of different ion channels and complex regulatory mechanisms that orchestrate molecular microarchitecture. We review recent evidence that a large number of ion channels associated with epilepsy are enriched at the AIS, making it a 'hotspot' for epileptogenesis. Furthermore, we present novel data on the clustering of GABRgamma2 receptors in the AIS of cortical and hippocampal neurons in a knock in mouse model of a human genetic epilepsy. This article highlights the molecular coincidence of epilepsy mutations at the AIS and reviews pathogenic mechanisms converging at the AIS.
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Affiliation(s)
- Verena C Wimmer
- Florey Neuroscience Institutes, University of Melbourne, Parkville 3010, Victoria, Australia
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Jedlicka P, Deller T, Schwarzacher SW. Computational modeling of GABAA receptor-mediated paired-pulse inhibition in the dentate gyrus. J Comput Neurosci 2010; 29:509-19. [DOI: 10.1007/s10827-010-0214-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 12/11/2009] [Accepted: 01/07/2010] [Indexed: 10/19/2022]
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