1
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Morris PG, Taylor JD, Paton JFR, Nogaret A. Single shot detection of alterations across multiple ionic currents from assimilation of cell membrane dynamics. Sci Rep 2024; 14:6031. [PMID: 38472404 DOI: 10.1038/s41598-024-56576-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
The dysfunction of ion channels is a causative factor in a variety of neurological diseases, thereby defining the implicated channels as key drug targets. The detection of functional changes in multiple specific ionic currents currently presents a challenge, particularly when the neurological causes are either a priori unknown, or are unexpected. Traditional patch clamp electrophysiology is a powerful tool in this regard but is low throughput. Here, we introduce a single-shot method for detecting alterations amongst a range of ion channel types from subtle changes in membrane voltage in response to a short chaotically driven current clamp protocol. We used data assimilation to estimate the parameters of individual ion channels and from these we reconstructed ionic currents which exhibit significantly lower error than the parameter estimates. Such reconstructed currents thereby become sensitive predictors of functional alterations in biological ion channels. The technique correctly predicted which ionic current was altered, and by approximately how much, following pharmacological blockade of BK, SK, A-type K+ and HCN channels in hippocampal CA1 neurons. We anticipate this assay technique could aid in the detection of functional changes in specific ionic currents during drug screening, as well as in research targeting ion channel dysfunction.
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Affiliation(s)
- Paul G Morris
- Department of Physics, University of Bath, Claverton Down, Bath, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Joseph D Taylor
- Department of Physics, University of Bath, Claverton Down, Bath, UK
| | - Julian F R Paton
- Manaaki Manawa - the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Alain Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, UK.
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2
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Alldred MJ, Pidikiti H, Heguy A, Roussos P, Ginsberg SD. Basal forebrain cholinergic neurons are vulnerable in a mouse model of Down syndrome and their molecular fingerprint is rescued by maternal choline supplementation. FASEB J 2023; 37:e22944. [PMID: 37191946 PMCID: PMC10292934 DOI: 10.1096/fj.202202111rr] [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: 12/19/2022] [Revised: 04/12/2023] [Accepted: 04/18/2023] [Indexed: 05/17/2023]
Abstract
Basal forebrain cholinergic neuron (BFCN) degeneration is a hallmark of Down syndrome (DS) and Alzheimer's disease (AD). Current therapeutics in these disorders have been unsuccessful in slowing disease progression, likely due to poorly understood complex pathological interactions and dysregulated pathways. The Ts65Dn trisomic mouse model recapitulates both cognitive and morphological deficits of DS and AD, including BFCN degeneration and has shown lifelong behavioral changes due to maternal choline supplementation (MCS). To test the impact of MCS on trisomic BFCNs, we performed laser capture microdissection to individually isolate choline acetyltransferase-immunopositive neurons in Ts65Dn and disomic littermates, in conjunction with MCS at the onset of BFCN degeneration. We utilized single population RNA sequencing (RNA-seq) to interrogate transcriptomic changes within medial septal nucleus (MSN) BFCNs. Leveraging multiple bioinformatic analysis programs on differentially expressed genes (DEGs) by genotype and diet, we identified key canonical pathways and altered physiological functions within Ts65Dn MSN BFCNs, which were attenuated by MCS in trisomic offspring, including the cholinergic, glutamatergic and GABAergic pathways. We linked differential gene expression bioinformatically to multiple neurological functions, including motor dysfunction/movement disorder, early onset neurological disease, ataxia and cognitive impairment via Ingenuity Pathway Analysis. DEGs within these identified pathways may underlie aberrant behavior in the DS mice, with MCS attenuating the underlying gene expression changes. We propose MCS ameliorates aberrant BFCN gene expression within the septohippocampal circuit of trisomic mice through normalization of principally the cholinergic, glutamatergic, and GABAergic signaling pathways, resulting in attenuation of underlying neurological disease functions.
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Affiliation(s)
- Melissa J. Alldred
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA
| | - Harshitha Pidikiti
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA
| | - Adriana Heguy
- Genome Technology Center, New York University Grossman School of Medicine, New York, NY, USA
| | - Panos Roussos
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA
- Departments of Genetics and Genomic Sciences and Psychiatry and the Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Stephen D. Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY, USA
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA
- Departments of Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY, USA
- NYU Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
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3
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Eom K, Lee HR, Hyun JH, An H, Lee YS, Ho WK, Lee SH. Gradual decorrelation of CA3 ensembles associated with contextual discrimination learning is impaired by Kv1.2 insufficiency. Hippocampus 2021; 32:193-216. [PMID: 34964210 DOI: 10.1002/hipo.23400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 11/30/2021] [Accepted: 12/12/2021] [Indexed: 12/13/2022]
Abstract
The associative network of hippocampal CA3 is thought to contribute to rapid formation of contextual memory from one-trial learning, but the network mechanisms underlying decorrelation of neuronal ensembles in CA3 is largely unknown. Kv1.2 expressions in rodent CA3 pyramidal cells (CA3-PCs) are polarized to distal apical dendrites, and its downregulation specifically enhances dendritic responses to perforant pathway (PP) synaptic inputs. We found that haploinsufficiency of Kv1.2 (Kcna2+/-) in CA3-PCs, but not Kv1.1 (Kcna1+/-), lowers the threshold for long-term potentiation (LTP) at PP-CA3 synapses, and that the Kcna2+/- mice are normal in discrimination of distinct contexts but impaired in discrimination of similar but slightly distinct contexts. We further examined the neuronal ensembles in CA3 and dentate gyrus (DG), which represent the two similar contexts using in situ hybridization of immediate early genes, Homer1a and Arc. The size and overlap of CA3 ensembles activated by the first visit to the similar contexts were not different between wild type and Kcna2+/- mice, but these ensemble parameters diverged over training days between genotypes, suggesting that abnormal plastic changes at PP-CA3 synapses of Kcna2+/- mice is responsible for the impaired pattern separation. Unlike CA3, DG ensembles were not different between two genotype mice. The DG ensembles were already separated on the first day, and their overlap did not further evolve. Eventually, the Kcna2+/- mice exhibited larger CA3 ensemble size and overlap upon retrieval of two contexts, compared to wild type or Kcna1+/- mice. These results suggest that sparse LTP at PP-CA3 synapse probably supervised by mossy fiber inputs is essential for gradual decorrelation of CA3 ensembles.
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Affiliation(s)
- Kisang Eom
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyoung Ro Lee
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jung Ho Hyun
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyunhoe An
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Republic of Korea
| | - Yong-Seok Lee
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Won-Kyung Ho
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Republic of Korea
| | - Suk-Ho Lee
- Cell Physiology Laboratory, Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Republic of Korea
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4
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Chou SM, Li KX, Huang MY, Chen C, Lin King YH, Li GG, Zhou W, Teo CF, Jan YN, Jan LY, Yang SB. Kv1.1 channels regulate early postnatal neurogenesis in mouse hippocampus via the TrkB signaling pathway. eLife 2021; 10:e58779. [PMID: 34018923 PMCID: PMC8208815 DOI: 10.7554/elife.58779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 05/20/2021] [Indexed: 12/20/2022] Open
Abstract
In the postnatal brain, neurogenesis occurs only within a few regions, such as the hippocampal sub-granular zone (SGZ). Postnatal neurogenesis is tightly regulated by factors that balance stem cell renewal with differentiation, and it gives rise to neurons that participate in learning and memory formation. The Kv1.1 channel, a voltage-gated potassium channel, was previously shown to suppress postnatal neurogenesis in the SGZ in a cell-autonomous manner. In this study, we have clarified the physiological and molecular mechanisms underlying Kv1.1-dependent postnatal neurogenesis. First, we discovered that the membrane potential of neural progenitor cells is highly dynamic during development. We further established a multinomial logistic regression model for cell-type classification based on the biophysical characteristics and corresponding cell markers. We found that the loss of Kv1.1 channel activity causes significant depolarization of type 2b neural progenitor cells. This depolarization is associated with increased tropomyosin receptor kinase B (TrkB) signaling and proliferation of neural progenitor cells; suppressing TrkB signaling reduces the extent of postnatal neurogenesis. Thus, our study defines the role of the Kv1.1 potassium channel in regulating the proliferation of postnatal neural progenitor cells in mouse hippocampus.
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Affiliation(s)
- Shu-Min Chou
- Institute of Biomedical Sciences, Academia SinicaTaipeiTaiwan
| | - Ke-Xin Li
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | | | - Chao Chen
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Yuan-Hung Lin King
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Neuroscience Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | | | - Wei Zhou
- Department of Anesthesia and Perioperative Care, University of California, San FranciscoSan FranciscoUnited States
| | - Chin Fen Teo
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Lily Yeh Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Shi-Bing Yang
- Institute of Biomedical Sciences, Academia SinicaTaipeiTaiwan
- Neuroscience Program of Academia Sinica, Academia SinicaTaipeiTaiwan
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5
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Cheret C, Ganzella M, Preobraschenski J, Jahn R, Ahnert-Hilger G. Vesicular Glutamate Transporters (SLCA17 A6, 7, 8) Control Synaptic Phosphate Levels. Cell Rep 2021; 34:108623. [PMID: 33440152 PMCID: PMC7809625 DOI: 10.1016/j.celrep.2020.108623] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 09/28/2020] [Accepted: 12/17/2020] [Indexed: 10/27/2022] Open
Abstract
Vesicular glutamate transporters (VGLUTs) fill synaptic vesicles with glutamate. VGLUTs were originally identified as sodium-dependent transporters of inorganic phosphate (Pi), but the physiological relevance of this activity remains unclear. Heterologous expression of all three VGLUTs greatly augments intracellular Pi levels. Using neuronal models, we show that translocation of VGLUTs to the plasma membrane during exocytosis results in highly increased Pi uptake. VGLUT-mediated Pi influx is counteracted by Pi efflux. Synaptosomes prepared from perinatal VGLUT2-/- mice that are virtually free of VGLUTs show drastically reduced cytosolic Pi levels and fail to import Pi. Glutamate partially competes with sodium (Na+)/Pi (NaPi)-uptake mediated by VGLUTs but does not appear to be transported. A nanobody that blocks glutamate transport by binding to the cytoplasmic domain of VGLUT1 abolishes Pi transport when co-expressed with VGLUT1. We conclude that VGLUTs have a dual function that is essential for both vesicular glutamate loading and Pi restoration in neurons.
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Affiliation(s)
- Cyril Cheret
- Institute for Integrative Neuroanatomy, Charité, Medical University of Berlin, 10115 Berlin, Germany
| | - Marcelo Ganzella
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, and University of Göttingen, 37077 Göttingen, Germany
| | - Julia Preobraschenski
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, and University of Göttingen, 37077 Göttingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, and University of Göttingen, 37077 Göttingen, Germany.
| | - Gudrun Ahnert-Hilger
- Institute for Integrative Neuroanatomy, Charité, Medical University of Berlin, 10115 Berlin, Germany; Laboratory of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, and University of Göttingen, 37077 Göttingen, Germany.
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6
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The potassium channel subunit K vβ1 serves as a major control point for synaptic facilitation. Proc Natl Acad Sci U S A 2020; 117:29937-29947. [PMID: 33168717 PMCID: PMC7703594 DOI: 10.1073/pnas.2000790117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nerve terminals generally engage in two opposite and essential forms of synaptic plasticity (facilitation or depression) that play critical roles in learning and memory. While the molecular components of both types of terminals are similar with regards to vesicle fusion, much less is known about their molecular control of electrical signaling. Measurements of the electrical impulses (action potentials) underlying these two forms of plasticity have been difficult in small nerve terminals due to their size. In this study we deployed optical physiology measurements to overcome this size barrier. Here, we identify a unique mechanism (Kvβ1 subunit) that enables broadening of the presynaptic action potentials that selectively supports synaptic facilitation, but does not alter any other aspects of nerve terminal function. Analysis of the presynaptic action potential’s (APsyn) role in synaptic facilitation in hippocampal pyramidal neurons has been difficult due to size limitations of axons. We overcame these size barriers by combining high-resolution optical recordings of membrane potential, exocytosis, and Ca2+ in cultured hippocampal neurons. These recordings revealed a critical and selective role for Kv1 channel inactivation in synaptic facilitation of excitatory hippocampal neurons. Presynaptic Kv1 channel inactivation was mediated by the Kvβ1 subunit and had a surprisingly rapid onset that was readily apparent even in brief physiological stimulation paradigms including paired-pulse stimulation. Genetic depletion of Kvβ1 blocked all broadening of the APsyn during high-frequency stimulation and eliminated synaptic facilitation without altering the initial probability of vesicle release. Thus, using all quantitative optical measurements of presynaptic physiology, we reveal a critical role for presynaptic Kv channels in synaptic facilitation at presynaptic terminals of the hippocampus upstream of the exocytic machinery.
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7
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Bacon TJ, Pickering AE, Mellor JR. Noradrenaline Release from Locus Coeruleus Terminals in the Hippocampus Enhances Excitation-Spike Coupling in CA1 Pyramidal Neurons Via β-Adrenoceptors. Cereb Cortex 2020; 30:6135-6151. [PMID: 32607551 PMCID: PMC7609922 DOI: 10.1093/cercor/bhaa159] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/13/2020] [Accepted: 05/13/2020] [Indexed: 12/29/2022] Open
Abstract
Release of the neuromodulator noradrenaline signals salience during wakefulness, flagging novel or important experiences to reconfigure information processing and memory representations in the hippocampus. Noradrenaline is therefore expected to enhance hippocampal responses to synaptic input; however, noradrenergic agonists have been found to have mixed and sometimes contradictory effects on Schaffer collateral synapses and the resulting CA1 output. Here, we examine the effects of endogenous, optogenetically driven noradrenaline release on synaptic transmission and spike output in mouse hippocampal CA1 pyramidal neurons. We show that endogenous noradrenaline release enhances the probability of CA1 pyramidal neuron spiking without altering feedforward excitatory or inhibitory synaptic inputs in the Schaffer collateral pathway. β-adrenoceptors mediate this enhancement of excitation-spike coupling by reducing the charge required to initiate action potentials, consistent with noradrenergic modulation of voltage-gated potassium channels. Furthermore, we find the likely effective concentration of endogenously released noradrenaline is sub-micromolar. Surprisingly, although comparable concentrations of exogenous noradrenaline cause robust depression of slow afterhyperpolarization currents, endogenous release of noradrenaline does not, indicating that endogenous noradrenaline release is targeted to specific cellular locations. These findings provide a mechanism by which targeted endogenous release of noradrenaline can enhance information transfer in the hippocampus in response to salient events.
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Affiliation(s)
- Travis J Bacon
- Centre for Synaptic Plasticity, University of Bristol, Bristol, UK
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK
| | - Anthony E Pickering
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK
- Bristol Anaesthesia, Pain & Critical Care Sciences, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol BS2 8HW, UK
| | - Jack R Mellor
- Centre for Synaptic Plasticity, University of Bristol, Bristol, UK
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK
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8
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Tian Y, Korn P, Tripathi P, Komnig D, Wiemuth D, Nikouee A, Classen A, Bolm C, Falkenburger BH, Lüscher B, Gründer S. The mono-ADP-ribosyltransferase ARTD10 regulates the voltage-gated K + channel Kv1.1 through protein kinase C delta. BMC Biol 2020; 18:143. [PMID: 33059680 PMCID: PMC7558731 DOI: 10.1186/s12915-020-00878-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 09/24/2020] [Indexed: 11/30/2022] Open
Abstract
Background ADP-ribosylation is a ubiquitous post-translational modification that involves both mono- and poly-ADP-ribosylation. ARTD10, also known as PARP10, mediates mono-ADP-ribosylation (MARylation) of substrate proteins. A previous screen identified protein kinase C delta (PKCδ) as a potential ARTD10 substrate, among several other kinases. The voltage-gated K+ channel Kv1.1 constitutes one of the dominant Kv channels in neurons of the central nervous system and the inactivation properties of Kv1.1 are modulated by PKC. In this study, we addressed the role of ARTD10-PKCδ as a regulator of Kv1.1. Results We found that ARTD10 inhibited PKCδ, which increased Kv1.1 current amplitude and the proportion of the inactivating current component in HeLa cells, indicating that ARTD10 regulates Kv1.1 in living cells. An inhibitor of ARTD10, OUL35, significantly decreased peak amplitude together with the proportion of the inactivating current component of Kv1.1-containing channels in primary hippocampal neurons, demonstrating that the ARTD10-PKCδ signaling cascade regulates native Kv1.1. Moreover, we show that the pharmacological blockade of ARTD10 increases excitability of hippocampal neurons. Conclusions Our results, for the first time, suggest that MARylation by ARTD10 controls neuronal excitability.
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Affiliation(s)
- Yuemin Tian
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Patricia Korn
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Priyanka Tripathi
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,Present address: Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Daniel Komnig
- Department of Neurology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany
| | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Azadeh Nikouee
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Arno Classen
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Carsten Bolm
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Björn H Falkenburger
- Department of Neurology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany.,Present address: Department of Neurology, Dresden University Medical Center, Fetscherstraße 74, 01307, Dresden, Germany
| | - Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
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9
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Zhou J, Brown AM, Lackey EP, Arancillo M, Lin T, Sillitoe RV. Purkinje cell neurotransmission patterns cerebellar basket cells into zonal modules defined by distinct pinceau sizes. eLife 2020; 9:55569. [PMID: 32990595 PMCID: PMC7561353 DOI: 10.7554/elife.55569] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 09/29/2020] [Indexed: 01/05/2023] Open
Abstract
Ramón y Cajal proclaimed the neuron doctrine based on circuit features he exemplified using cerebellar basket cell projections. Basket cells form dense inhibitory plexuses that wrap Purkinje cell somata and terminate as pinceaux at the initial segment of axons. Here, we demonstrate that HCN1, Kv1.1, PSD95 and GAD67 unexpectedly mark patterns of basket cell pinceaux that map onto Purkinje cell functional zones. Using cell-specific genetic tracing with an Ascl1CreERT2 mouse conditional allele, we reveal that basket cell zones comprise different sizes of pinceaux. We tested whether Purkinje cells instruct the assembly of inhibitory projections into zones, as they do for excitatory afferents. Genetically silencing Purkinje cell neurotransmission blocks the formation of sharp Purkinje cell zones and disrupts excitatory axon patterning. The distribution of pinceaux into size-specific zones is eliminated without Purkinje cell GABAergic output. Our data uncover the cellular and molecular diversity of a foundational synapse that revolutionized neuroscience.
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Affiliation(s)
- Joy Zhou
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States
| | - Elizabeth P Lackey
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States
| | - Marife Arancillo
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States
| | - Tao Lin
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States
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10
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Transcriptome Analysis of iPSC-Derived Neurons from Rubinstein-Taybi Patients Reveals Deficits in Neuronal Differentiation. Mol Neurobiol 2020; 57:3685-3701. [PMID: 32562237 PMCID: PMC7399686 DOI: 10.1007/s12035-020-01983-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/08/2020] [Indexed: 12/17/2022]
Abstract
Rubinstein-Taybi syndrome (RSTS) is a rare multisystem developmental disorder with moderate to severe intellectual disability caused by heterozygous mutations of either CREBBP or EP300 genes encoding CBP/p300 chromatin regulators. We explored the gene programs and processes underlying the morphological and functional alterations shown by iPSC-derived neurons modeling RSTS to bridge the molecular changes resulting from defective CBP/p300 to cognitive impairment. By global transcriptome analysis, we compared the differentially expressed genes (DEGs) marking the transition from iPSC-derived neural progenitors to cortical neurons (iNeurons) of five RSTS patients carrying private CREBBP/EP300 mutations and manifesting differently graded neurocognitive signs with those of four healthy controls. Our data shows a defective and altered neuroprogenitor to neuron transcriptional program in the cells from RSTS patients. First, transcriptional regulation is weaker in RSTS as less genes than in controls are modulated, including genes of key processes of mature functional neurons, such as those for voltage-gated channels and neurotransmitters and their receptors. Second, regulation is subverted as genes acting at pre-terminal stages of neural differentiation in cell polarity and adhesive functions (members of the cadherin family) and axon extension/guidance (members of the semaphorins and SLIT receptors families) are improperly upregulated. Impairment or delay of RSTS neuronal differentiation program is also evidenced by decreased modulation of the overall number of neural differentiation markers, significantly impacting the initial and final stages of the differentiation cascade. Last, extensive downregulation of genes for RNA/DNA metabolic processes confirms that RSTS is a global transcription disorder, consistent with a syndrome driven by chromatin dysregulation. Interestingly, the morphological and functional alterations we have previously appointed as biomarkers of RSTS iNeurons provide functional support to the herein designed transcriptome profile pointing to key dysregulated neuronal genes as main contributors to patients’ cognitive deficit. The impact of RSTS transcriptome may go beyond RSTS as comparison of dysregulated genes across modeled neurodevelopmental disorders could unveil convergent genes of cognitive impairment.
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11
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Zhang Z, Qiu W, Gong H, Li G, Jiang Q, Liang P, Zheng H, Zhang P. Low-intensity ultrasound suppresses low-Mg2+-induced epileptiform discharges in juvenile mouse hippocampal slices. J Neural Eng 2019; 16:036006. [DOI: 10.1088/1741-2552/ab0b9a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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12
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Niespodziany I, Mullier B, André VM, Ghisdal P, Jnoff E, Moreno-Delgado D, Swinnen D, Sands Z, Wood M, Wolff C. Discovery of a small molecule modulator of the Kv1.1/Kvβ1 channel complex that reduces neuronal excitability and in vitro epileptiform activity. CNS Neurosci Ther 2018; 25:442-451. [PMID: 30242974 DOI: 10.1111/cns.13060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 11/27/2022] Open
Abstract
AIMS Kv1.1 (KCNA1) channels contribute to the control of neuronal excitability and have been associated with epilepsy. Kv1.1 channels can associate with the cytoplasmic Kvβ1 subunit resulting in rapid inactivating A-type currents. We hypothesized that removal of channel inactivation, by modulating Kv1.1/Kvβ1 interaction with a small molecule, would lead to decreased neuronal excitability and anticonvulsant activity. METHODS We applied high-throughput screening to identify ligands able to modulate the Kv1.1-T1 domain/Kvβ1 protein complex. We then selected a compound that was characterized on recombinant Kv1.1/Kvβ1 channels by electrophysiology and further evaluated on sustained neuronal firing and on in vitro epileptiform activity using a high K+ -low Ca2+ model in hippocampal slices. RESULTS We identified a novel compound able to modulate the interaction of the Kv1.1/Kvβ1 complex and that produced a functional inhibition of Kv1.1/Kvβ1 channel inactivation. We demonstrated that this compound reduced the sustained repetitive firing in hippocampal neurons and was able to abolish the development of in vitro epileptiform activity. CONCLUSIONS This study describes a rational drug discovery approach for the identification of novel ligands that inhibit Kv1.1 channel inactivation and provides pharmacological evidence that such a mechanism translates into physiological effects by reducing in vitro epileptiform activity.
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Affiliation(s)
| | - Brice Mullier
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | | | - Philippe Ghisdal
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Eric Jnoff
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | | | - Dominique Swinnen
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Zara Sands
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Martyn Wood
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Christian Wolff
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
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13
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Zhu P, Li J, Zhang L, Liang Z, Tang B, Liao WP, Yi YH, Su T. Development-related aberrations in Kv1.1 α-subunit exert disruptive effects on bioelectrical activities of neurons in a mouse model of fragile X syndrome. Prog Neuropsychopharmacol Biol Psychiatry 2018; 84:140-151. [PMID: 29481897 DOI: 10.1016/j.pnpbp.2018.02.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 02/22/2018] [Accepted: 02/22/2018] [Indexed: 10/18/2022]
Abstract
Kv1.1, a Shaker homologue potassium channel, plays a critical role in homeostatic regulation of neuronal excitability. Aberrations in the functional properties of Kv1.1 have been implicated in several neurological disorders featured by neuronal hyperexcitability. Fragile X syndrome (FXS), the most common form of inherited mental retardation, is characterized by hyperexcitability in neural network and intrinsic membrane properties. The Kv1.1 channel provides an intriguing mechanistic candidate for FXS. We investigated the development-related expression pattern of the Kv1.1 α-subunit by using a Fmr1 knockout (KO) mouse model of FXS. Markedly decreased protein expression of Kv1.1 was found in neonatal and adult stages when compared to age-matched wild-type (WT) mice. Immunohistochemical investigations supported the delayed development-related increases in Kv1.1 expression, especially in CA3 pyramidal neurons. By applying a Kv1.1-specific blocker, dendrotoxin-κ (DTX-κ), we isolated the Kv1.1-mediated currents in the CA3 pyramidal neurons. The isolated DTX-κ-sensitive current of neurons from KO mice exhibited decreased amplitude, lower threshold of activation, and faster recovery from inactivation. The equivalent reduction in potassium current in the WT neurons following application of the appropriate amount of DTX-κ reproduced the enhanced firing abilities of KO neurons, suggesting the Kv1.1 channel as a critical contributor to the hyperexcitability of KO neurons. The role of Kv1.1 in controlling neuronal discharges was further supported by the parallel developmental trajectories of Kv1.1 expression, current amplitude, and discharge impacts, with a significant correlation between the amplitude of Kv1.1-mediated currents and Kv1.1-blocking-induced firing enhancement. These data suggest that the expression of the Kv1.1 α-subunit has a profound pathological relevance to hyperexcitability in FXS, as well as implications for normal development, maintenance, and control of neuronal activities.
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Affiliation(s)
- Pingping Zhu
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China; Department of Neurology, Guangzhou Red Cross Hospital, Medical College, Jinan University, Guangzhou, China
| | - Jialing Li
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Liting Zhang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Zhanrong Liang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Bin Tang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Wei-Ping Liao
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Yong-Hong Yi
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Tao Su
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China.
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14
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Rangaraju S, Dammer EB, Raza SA, Rathakrishnan P, Xiao H, Gao T, Duong DM, Pennington MW, Lah JJ, Seyfried NT, Levey AI. Identification and therapeutic modulation of a pro-inflammatory subset of disease-associated-microglia in Alzheimer's disease. Mol Neurodegener 2018; 13:24. [PMID: 29784049 PMCID: PMC5963076 DOI: 10.1186/s13024-018-0254-8] [Citation(s) in RCA: 233] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 04/30/2018] [Indexed: 02/06/2023] Open
Abstract
Background Disease-associated-microglia (DAM) represent transcriptionally-distinct and neurodegeneration-specific microglial profiles with unclear significance in Alzheimer’s disease (AD). An understanding of heterogeneity within DAM and their key regulators may guide pre-clinical experimentation and drug discovery. Methods Weighted co-expression network analysis (WGCNA) was applied to existing microglial transcriptomic datasets from neuroinflammatory and neurodegenerative disease mouse models to identify modules of highly co-expressed genes. These modules were contrasted with known signatures of homeostatic microglia and DAM to reveal novel molecular heterogeneity within DAM. Flow cytometric validation studies were performed to confirm existence of distinct DAM sub-populations in AD mouse models predicted by WGCNA. Gene ontology analyses coupled with bioinformatics approaches revealed drug targets and transcriptional regulators of microglial modules predicted to favorably modulate neuroinflammation in AD. These guided in-vivo and in-vitro studies in mouse models of neuroinflammation and neurodegeneration (5xFAD) to determine whether inhibition of pro-inflammatory gene expression and promotion of amyloid clearance was feasible. We determined the human relevance of these findings by integrating our results with AD genome-wide association studies and human AD and non-disease post-mortem brain proteomes. Results WGCNA applied to microglial gene expression data revealed a transcriptomic framework of microglial activation that predicted distinct pro-inflammatory and anti-inflammatory phenotypes within DAM, which we confirmed in AD and aging models by flow cytometry. Pro-inflammatory DAM emerged earlier in mouse models of AD and were characterized by pro-inflammatory genes (Tlr2, Ptgs2, Il12b, Il1b), surface marker CD44, potassium channel Kv1.3 and regulators (NFkb, Stat1, RelA) while anti-inflammatory DAM expressed phagocytic genes (Igf1, Apoe, Myo1e), surface marker CXCR4 with distinct regulators (LXRα/β, Atf1). As neuro-immunomodulatory strategies, we validated LXRα/β agonism and Kv1.3 blockade by ShK-223 peptide that promoted anti-inflammatory DAM, inhibited pro-inflammatory DAM and augmented Aβ clearance in AD models. Human AD-risk genes were highly represented within homeostatic microglia suggesting causal roles for early microglial dysregulation in AD. Pro-inflammatory DAM proteins were positively associated with neuropathology and preceded cognitive decline confirming the therapeutic relevance of inhibiting pro-inflammatory DAM in AD. Conclusions We provide a predictive transcriptomic framework of microglial activation in neurodegeneration that can guide pre-clinical studies to characterize and therapeutically modulate neuroinflammation in AD. Electronic supplementary material The online version of this article (10.1186/s13024-018-0254-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Eric B Dammer
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | - Syed Ali Raza
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | | | - Hailian Xiao
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Tianwen Gao
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | - Duc M Duong
- Department of Biochemistry, Emory University, Atlanta, GA, 30322, USA
| | | | - James J Lah
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
| | | | - Allan I Levey
- Department of Neurology, Emory University, Atlanta, GA, 30322, USA
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15
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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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16
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Ondacova K, Moravcikova L, Jurkovicova D, Lacinova L. Fibrotic scar model and TGF-β1 differently modulate action potential firing and voltage-dependent ion currents in hippocampal neurons in primary culture. Eur J Neurosci 2017; 46:2161-2176. [DOI: 10.1111/ejn.13663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 07/17/2017] [Accepted: 07/21/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Katarina Ondacova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
| | - Lucia Moravcikova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
| | - Dana Jurkovicova
- KRD Molecular Technologies s. r. o.; Bratislava Slovakia
- Biomedical Research Center; Cancer Research Institute; Slovak Academy of Sciences; Bratislava Slovakia
| | - Lubica Lacinova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
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17
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Zhang Q, Yao J, Guang Y, Liang S, Guan J, Qin H, Liao X, Jin W, Zhang J, Pan J, Jia H, Yan J, Feng Z, Li W, Chen X. Locomotion-Related Population Cortical Ca 2+ Transients in Freely Behaving Mice. Front Neural Circuits 2017; 11:24. [PMID: 28439229 PMCID: PMC5383702 DOI: 10.3389/fncir.2017.00024] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 03/27/2017] [Indexed: 11/25/2022] Open
Abstract
Locomotion involves complex neural activity throughout different cortical and subcortical networks. The primary motor cortex (M1) receives a variety of projections from different brain regions and is responsible for executing movements. The primary visual cortex (V1) receives external visual stimuli and plays an important role in guiding locomotion. Understanding how exactly the M1 and the V1 are involved in locomotion requires recording the neural activities in these areas in freely moving animals. Here, we used an optical fiber-based method for the real-time monitoring of neuronal population activities in freely moving mice. We combined the bulk loading of a synthetic Ca2+ indicator and the optical fiber-based Ca2+ recordings of neuronal activities. An optical fiber 200 μm in diameter can detect the coherent activity of a subpopulation of neurons. In layer 5 of the M1 and V1, we showed that population Ca2+ transients reliably occurred preceding the impending locomotion. Interestingly, the M1 Ca2+ transients started ~100 ms earlier than that in V1. Furthermore, the population Ca2+ transients were robustly correlated with head movements. Thus, our work provides a simple but efficient approach for monitoring the cortical Ca2+ activity of a local cluster of neurons during locomotion in freely moving animals.
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Affiliation(s)
- Quanchao Zhang
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Jiwei Yao
- Institute of Urinary Surgery, Southwest Hospital, Third Military Medical UniversityChongqing, China
| | - Yu Guang
- Department of Psychology, Third Military Medical UniversityChongqing, China
| | - Shanshan Liang
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Jiangheng Guan
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Han Qin
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Xiang Liao
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Wenjun Jin
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Jianxiong Zhang
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Junxia Pan
- Brain Research Center, Third Military Medical UniversityChongqing, China
| | - Hongbo Jia
- Brain Research Instrument Innovation Center, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of SciencesSuzhou, China
| | - Junan Yan
- Institute of Urinary Surgery, Southwest Hospital, Third Military Medical UniversityChongqing, China
| | - Zhengzhi Feng
- Department of Psychology, Third Military Medical UniversityChongqing, China
| | - Weibing Li
- Institute of Urinary Surgery, Southwest Hospital, Third Military Medical UniversityChongqing, China.,Clinical Center for Urological Disease, The Third Affiliated Hospital, Chongqing Medical UniversityChongqing, China
| | - Xiaowei Chen
- Brain Research Center, Third Military Medical UniversityChongqing, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
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18
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The role of axonal Kv1 channels in CA3 pyramidal cell excitability. Sci Rep 2017; 7:315. [PMID: 28331203 PMCID: PMC5428268 DOI: 10.1038/s41598-017-00388-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 02/22/2017] [Indexed: 01/24/2023] Open
Abstract
Axonal ion channels control spike initiation and propagation along the axon and determine action potential waveform. We show here that functional suppression of axonal Kv1 channels with local puff of dendrotoxin (DTx), laser or mechanical axotomy significantly increased excitability measured in the cell body. Importantly, the functional effect of DTx puffing or axotomy was not limited to the axon initial segment but was also seen on axon collaterals. In contrast, no effects were observed when DTx was puffed on single apical dendrites or after single dendrotomy. A simple model with Kv1 located in the axon reproduced the experimental observations and showed that the distance at which the effects of axon collateral cuts are seen depends on the axon space constant. In conclusion, Kv1 channels located in the axon proper greatly participate in intrinsic excitability of CA3 pyramidal neurons. This finding stresses the importance of the axonal compartment in the regulation of intrinsic neuronal excitability.
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19
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KV1 and KV3 Potassium Channels Identified at Presynaptic Terminals of the Corticostriatal Synapses in Rat. Neural Plast 2016; 2016:8782518. [PMID: 27379187 PMCID: PMC4917754 DOI: 10.1155/2016/8782518] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/12/2016] [Accepted: 05/16/2016] [Indexed: 12/19/2022] Open
Abstract
In the last years it has been increasingly clear that KV-channel activity modulates neurotransmitter release. The subcellular localization and composition of potassium channels are crucial to understanding its influence on neurotransmitter release. To investigate the role of KV in corticostriatal synapses modulation, we combined extracellular recording of population-spike and pharmacological blockage with specific and nonspecific blockers to identify several families of KV channels. We induced paired-pulse facilitation (PPF) and studied the changes in paired-pulse ratio (PPR) before and after the addition of specific KV blockers to determine whether particular KV subtypes were located pre- or postsynaptically. Initially, the presence of KV channels was tested by exposing brain slices to tetraethylammonium or 4-aminopyridine; in both cases we observed a decrease in PPR that was dose dependent. Further experiments with tityustoxin, margatoxin, hongotoxin, agitoxin, dendrotoxin, and BDS-I toxins all rendered a reduction in PPR. In contrast heteropodatoxin and phrixotoxin had no effect. Our results reveal that corticostriatal presynaptic KV channels have a complex stoichiometry, including heterologous combinations KV1.1, KV1.2, KV1.3, and KV1.6 isoforms, as well as KV3.4, but not KV4 channels. The variety of KV channels offers a wide spectrum of possibilities to regulate neurotransmitter release, providing fine-tuning mechanisms to modulate synaptic strength.
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20
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Petersen AV, Cotel F, Perrier JF. Plasticity of the Axon Initial Segment: Fast and Slow Processes with Multiple Functional Roles. Neuroscientist 2016; 23:364-373. [PMID: 27143656 DOI: 10.1177/1073858416648311] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The axon initial segment (AIS) is a key neuronal compartment because it is responsible for action potential initiation. The local density of Na+ channels, the biophysical properties of K+ channels, as well as the length and diameter of the AIS determine the spiking of neurons. These parameters undergo important modifications during development. The development of the AIS is governed by intrinsic mechanisms. In addition, surrounding neuronal networks modify its maturation. As a result, neurons get tuned to particular physiological functions. Neuronal activity also influences the morphology of the mature AIS. When excitatory neurons are hyperactive, their AIS undergo structural changes that decrease their excitability and thereby maintain the activity within a given range. These slow homeostatic regulatory mechanisms occur on a time scale of hours or days. In contrast, the activation of metabotropic receptors modulates the properties of ion channels expressed at the AIS within seconds and consequently produces fast adjustments of neuronal excitability. Recent results suggest that this plasticity plays important roles in physiological functions as diverse as memory formation, hearing, and motor control.
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Affiliation(s)
- Anders Victor Petersen
- 1 Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Florence Cotel
- 2 Queensland Brain Institute, University of Queensland, St Lucia, Australia
| | - Jean-François Perrier
- 1 Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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21
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Hyun JH, Eom K, Lee KH, Bae JY, Bae YC, Kim MH, Kim S, Ho WK, Lee SH. Kv1.2 mediates heterosynaptic modulation of direct cortical synaptic inputs in CA3 pyramidal cells. J Physiol 2015; 593:3617-43. [PMID: 26047212 DOI: 10.1113/jp270372] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 05/26/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We investigated the cellular mechanisms underlying mossy fibre-induced heterosynaptic long-term potentiation of perforant path (PP) inputs to CA3 pyramidal cells. Here we show that this heterosynaptic potentiation is mediated by downregulation of Kv1.2 channels. The downregulation of Kv1.2 preferentially enhanced PP-evoked EPSPs which occur at distal apical dendrites. Such enhancement of PP-EPSPs required activation of dendritic Na(+) channels, and its threshold was lowered by downregulation of Kv1.2. Our results may provide new insights into the long-standing question of how mossy fibre inputs constrain the CA3 network to sparsely represent direct cortical inputs. ABSTRACT A short high frequency stimulation of mossy fibres (MFs) induces long-term potentiation (LTP) of direct cortical or perforant path (PP) synaptic inputs in hippocampal CA3 pyramidal cells (CA3-PCs). However, the cellular mechanism underlying this heterosynaptic modulation remains elusive. Previously, we reported that repetitive somatic firing at 10 Hz downregulates Kv1.2 in the CA3-PCs. Here, we show that MF inputs induce similar somatic firing and downregulation of Kv1.2 in the CA3-PCs. The effect of Kv1.2 downregulation was specific to PP synaptic inputs that arrive at distal apical dendrites. We found that the somatodendritic expression of Kv1.2 is polarized to distal apical dendrites. Compartmental simulations based on this finding suggested that passive normalization of synaptic inputs and polarized distributions of dendritic ionic channels may facilitate the activation of dendritic Na(+) channels preferentially at distal apical dendrites. Indeed, partial block of dendritic Na(+) channels using 10 nm tetrodotoxin brought back the enhanced PP-evoked excitatory postsynaptic potentials (PP-EPSPs) to the baseline level. These results indicate that activity-dependent downregulation of Kv1.2 in CA3-PCs mediates MF-induced heterosynaptic LTP of PP-EPSPs by facilitating activation of Na(+) channels at distal apical dendrites.
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Affiliation(s)
- Jung Ho Hyun
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kisang Eom
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kyu-Hee Lee
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Jin Young Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Republic of Korea
| | - Yong Chul Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, 700-412, Republic of Korea
| | - Myoung-Hwan Kim
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Sooyun Kim
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Won-Kyung Ho
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Suk-Ho Lee
- Cell Physiology Laboratory, Department of Physiology and bioMembrane Plasticity Research Centre, Seoul National University College of Medicine and Neuroscience Research Institute, Seoul National University Medical Research Centre, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
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22
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Giglio AM, Storm JF. Postnatal development of temporal integration, spike timing and spike threshold regulation by a dendrotoxin-sensitive K+current in rat CA1 hippocampal cells. Eur J Neurosci 2013; 39:12-23. [DOI: 10.1111/ejn.12385] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 08/30/2013] [Accepted: 09/10/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Anna M. Giglio
- Institute of Basal Medicine; Department of Physiology and Centre of Molecular Biology and Neuroscience; University of Oslo; PB 1104 Blindern, 0317 Oslo Norway
| | - Johan F. Storm
- Institute of Basal Medicine; Department of Physiology and Centre of Molecular Biology and Neuroscience; University of Oslo; PB 1104 Blindern, 0317 Oslo Norway
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23
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Hyun JH, Eom K, Lee KH, Ho WK, Lee SH. Activity-dependent downregulation of D-type K+ channel subunit Kv1.2 in rat hippocampal CA3 pyramidal neurons. J Physiol 2013; 591:5525-40. [PMID: 23981714 DOI: 10.1113/jphysiol.2013.259002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The intrinsic excitability of neurons plays a critical role in the encoding of memory at Hebbian synapses and in the coupling of synaptic inputs to spike generation. It has not been studied whether somatic firing at a physiologically relevant frequency can induce intrinsic plasticity in hippocampal CA3 pyramidal cells (CA3-PCs). Here, we show that a conditioning train of 20 action potentials (APs) at 10 Hz causes a persistent reduction in the input conductance and an acceleration of the AP onset time in CA3-PCs, but not in CA1-PCs. Induction of such long-term potentiation of intrinsic excitability (LTP-IE) was accompanied by a reduction in the D-type K(+) current, and was abolished by the inhibition of endocytosis or protein tyrosine kinase (PTK). Consistently, the CA3-PCs from Kv1.2 knock-out mice displayed no LTP-IE with the same conditioning. Furthermore, the induction of LTP-IE depended on the back-propagating APs (bAPs) and intact distal apical dendrites. These results indicate that LTP-IE is mediated by the internalization of Kv1.2 channels from the distal regions of apical dendrites, which is triggered by bAP-induced dendritic Ca(2+) signalling and the consequent activation of PTK.
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Affiliation(s)
- Jung Ho Hyun
- S.-H. Lee: Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea.
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Activation of lysophosphatidic acid receptor by gintonin inhibits Kv1.2 channel activity: Involvement of tyrosine kinase and receptor protein tyrosine phosphatase α. Neurosci Lett 2013; 548:143-8. [DOI: 10.1016/j.neulet.2013.05.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 05/16/2013] [Accepted: 05/20/2013] [Indexed: 02/07/2023]
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25
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Serotonergic modulation of LTP at excitatory and inhibitory synapses in the developing rat visual cortex. Neuroscience 2013; 238:148-58. [DOI: 10.1016/j.neuroscience.2013.02.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 02/06/2013] [Accepted: 02/08/2013] [Indexed: 11/21/2022]
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Electrophysiological properties and synaptic function of mesenchymal stem cells during neurogenic differentiation - a mini-review. Int J Artif Organs 2012; 35:323-37. [PMID: 22505200 DOI: 10.5301/ijao.5000085] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2011] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Mesenchymal stem cells (MSCs) have gained considerable interest due to their potential use in cell therapies and tissue engineering. They have been reported to differentiate into various anchorage-dependent cell types, including bone, cartilage, and tendon. Our focus is on the differentiation of MSCs into neuron-like cells through the use of soluble chemical stimuli or specific growth factor supplements. The resulting cells appear to adopt neural phenotypes and express some typical neuronal markers, however, their electrophysiological properties and synaptic function remains unclear. RESULTS This mini-review illustrates how particular characteristics, electrophysiological properties, and synaptic functions of MSCs change during their neuronal differentiation. In particular we focus on changes in ion currents, ion channels, synaptic communication, and neurotransmitter release. We also highlight conflicting results, caused by inconsistencies in the experimental conditions used and in the methodologies adopted. CONCLUSIONS We conclude that there is insufficient data and that further, carefully controlled investigations are required in order to ascertain whether MSC-derived neuron-like cells can exhibit the necessary neuronal functions to become clinically relevant for use in neural repairs.
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Huang CY, Chu D, Hwang WC, Tsaur ML. Coexpression of high-voltage-activated ion channels Kv3.4 and Cav1.2 in pioneer axons during pathfinding in the developing rat forebrain. J Comp Neurol 2012; 520:3650-72. [DOI: 10.1002/cne.23119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Abstract
Voltage-gated K(+) channels (Kv) represent the largest family of genes in the K(+) channel family. The Kv1 subfamily plays an essential role in the initiation and shaping of action potentials, influencing action potential firing patterns and controlling neuronal excitability. Overlapping patterns with differential expression and precise localization of Kv1.1 and Kv1.2 channels targeted to specialized subcellular compartments contribute to distinctive patterns of neuronal excitability. Dynamic regulation of the components in these subcellular domains help to finely tune the cellular and regional networks. Disruption of the expression, distribution, and density of these channels through deletion or mutation of the genes encoding these channels, Kcna1 and Kcna2, is associated with neurologic pathologies including epilepsy and ataxia in humans and in rodent models. Kv1.1 and Kv1.2 knockout mice both have seizures beginning early in development; however, each express a different seizure type (pathway), although the channels are from the same subfamily and are abundantly coexpressed. Voltage-gated ion channels clustered in specific locations may present a novel therapeutic target for influencing excitability in neurologic disorders associated with some channelopathies.
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Affiliation(s)
- Carol A Robbins
- Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Seattle, WA 98195, USA
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Yang SB, Mclemore KD, Tasic B, Luo L, Jan YN, Jan LY. Kv1.1-dependent control of hippocampal neuron number as revealed by mosaic analysis with double markers. J Physiol 2012; 590:2645-58. [PMID: 22411008 DOI: 10.1113/jphysiol.2012.228486] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Megencephaly, or mceph, is a spontaneous frame-shift mutation of the mouse Kv1.1 gene. This mceph mutation results in a truncated Kv1.1 channel α-subunit without the channel pore domain or the voltage sensor. Interestingly, mceph/mceph mouse brains are enlarged and – unlike wild-type mouse brains – they keep growing throughout adulthood, especially in the hippocampus and ventral cortex. We used mosaic analysis with double markers (MADM) to identify the underlying mechanism. In mceph-MADM6 mice with only a small fraction of neurons homozygous for the mceph mutation, those homozygous mceph/mceph neurons in the hippocampus are more abundant than wild-type neurons produced by sister neural progenitors. In contrast, neither mceph/mceph astrocytes, nor neurons in the adjacent dorsal cortex (including the entorhinal and parietal cortex) exhibited overgrowth in the adult brain. The sizes of mceph/mceph hippocampal neurons were comparable to mceph/+ or wild-type neurons. Our mosaic analysis reveals that loss of Kv1.1 function causes an overproduction of hippocampal neurons, leading to an enlarged brain phenotype.
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Affiliation(s)
- Shi-Bing Yang
- Howard Hughes Medical Institute, Department of Physiology, University of California–San Francisco, San Francisco, CA, USA
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Iwasaki S, Nakajima T, Chihara Y, Inoue A, Fujimoto C, Yamasoba T. Developmental changes in the expression of Κv1 potassium channels in rat vestibular ganglion cells. Brain Res 2011; 1429:29-35. [PMID: 22079321 DOI: 10.1016/j.brainres.2011.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 09/21/2011] [Accepted: 10/10/2011] [Indexed: 12/01/2022]
Abstract
The primary afferent neurons of the vestibular ganglion convey sensory information from hair cells in the semicircular canals and otolith organs to the vestibular nuclei, the adjacent brainstem and the cerebellum. The intrinsic firing properties of vestibular ganglion cells (VGCs) are heterogeneous and have been classified into phasic, intermediate and tonic firing types on the basis of their response to injected depolarizing currents. A previous study from our group showed that the proportion of phasic discharging VGCs decreased during the first postnatal weeks. Moreover, α-dendrotoxin (α-DTX), a Kv1 potassium channels antagonist, turned neuron phasic firing to tonic, thus suggesting that these channels play an important role in the developmental changes of VGCs firing patterns. Here, by using immunohistochemistry, Western blotting and quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR), we explored the change in the expression of α-DTX-sensitive K(+) channels, Kv1.1, Kv1.2 and Kv1.6 in rat VGCs during early postnatal periods. We showed that expression of Kv1.6 protein is down-regulated together with expression of Kv1.6 mRNA after postnatal day 7 in rat VGCs whereas expression of Kv1.1 and Kv1.2 proteins did not change during the same developmental period. Our results suggest that down-regulation of the Kv1.6 protein and mRNA may be associated with maturation of excitable properties of primary vestibular neurons.
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Affiliation(s)
- Shinichi Iwasaki
- Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
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Bucher D, Goaillard JM. Beyond faithful conduction: short-term dynamics, neuromodulation, and long-term regulation of spike propagation in the axon. Prog Neurobiol 2011; 94:307-46. [PMID: 21708220 PMCID: PMC3156869 DOI: 10.1016/j.pneurobio.2011.06.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 05/27/2011] [Accepted: 06/07/2011] [Indexed: 12/13/2022]
Abstract
Most spiking neurons are divided into functional compartments: a dendritic input region, a soma, a site of action potential initiation, an axon trunk and its collaterals for propagation of action potentials, and distal arborizations and terminals carrying the output synapses. The axon trunk and lower order branches are probably the most neglected and are often assumed to do nothing more than faithfully conducting action potentials. Nevertheless, there are numerous reports of complex membrane properties in non-synaptic axonal regions, owing to the presence of a multitude of different ion channels. Many different types of sodium and potassium channels have been described in axons, as well as calcium transients and hyperpolarization-activated inward currents. The complex time- and voltage-dependence resulting from the properties of ion channels can lead to activity-dependent changes in spike shape and resting potential, affecting the temporal fidelity of spike conduction. Neural coding can be altered by activity-dependent changes in conduction velocity, spike failures, and ectopic spike initiation. This is true under normal physiological conditions, and relevant for a number of neuropathies that lead to abnormal excitability. In addition, a growing number of studies show that the axon trunk can express receptors to glutamate, GABA, acetylcholine or biogenic amines, changing the relative contribution of some channels to axonal excitability and therefore rendering the contribution of this compartment to neural coding conditional on the presence of neuromodulators. Long-term regulatory processes, both during development and in the context of activity-dependent plasticity may also affect axonal properties to an underappreciated extent.
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Affiliation(s)
- Dirk Bucher
- The Whitney Laboratory and Department of Neuroscience, University of Florida, St. Augustine, FL 32080, USA.
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K(V)7/KCNQ channels are functionally expressed in oligodendrocyte progenitor cells. PLoS One 2011; 6:e21792. [PMID: 21750731 PMCID: PMC3130044 DOI: 10.1371/journal.pone.0021792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 06/12/2011] [Indexed: 11/26/2022] Open
Abstract
Background KV7/KCNQ channels are widely expressed in neurons and they have multiple important functions, including control of excitability, spike afterpotentials, adaptation, and theta resonance. Mutations in KCNQ genes have been demonstrated to associate with human neurological pathologies. However, little is known about whether KV7/KCNQ channels are expressed in oligodendrocyte lineage cells (OLCs) and what their functions in OLCs. Methods and Findings In this study, we characterized KV7/KCNQ channels expression in rat primary cultured OLCs by RT-PCR, immunostaining and electrophysiology. KCNQ2-5 mRNAs existed in all three developmental stages of rat primary cultured OLCs. KV7/KCNQ proteins were also detected in oligodendrocyte progenitor cells (OPCs, early developmental stages of OLCs) of rat primary cultures and cortex slices. Voltage-clamp recording revealed that the IM antagonist XE991 significantly reduced KV7/KCNQ channel current (IK(Q)) in OPCs but not in differentiated oligodendrocytes. In addition, inhibition of KV7/KCNQ channels promoted OPCs motility in vitro. Conclusions These findings showed that KV7/KCNQ channels were functionally expressed in rat primary cultured OLCs and might play an important role in OPCs functioning in physiological or pathological conditions.
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Abstract
STUDY DESIGN Responses of human mesenchymal stem cells from bone marrow (hBMSCs) were analyzed under chemical conditions, and then characterization of ion channels was evaluated by whole-cell patch clamp. OBJECTIVE To explore the possibility of differentiation of human bone marrow-derived mesenchymal stem cells into neuron-like cells in vitro under different conditions. SUMMARY OF BACKGROUND DATA The generation of mesenchymal stem cells into neuron-like cells has been studied. However, few of these studies characterized functional properties of the differentiated hBMSCs. METHODS hBMSCs (Passage 2) were expanded and cultured in vitro. After Passage 5 was subcultured, the cells were induced by cytokines and antioxidants. Morphologic observation, immunocytochemistry, Western blot analysis, and patch-clamp techniques were performed to evaluate properties of treated and control groups. RESULTS The differentiated neuronal cells from hBMSCs not only expressed neuron phenotype and membrane channel protein including Nav1.6, Kv1.2, Kv1.3, and Cav1.2 but also exhibited functional ion currents. Both hBMSCs and differentiated cells expressed Nav1.6, Kv1.2, Kv1.3, and Cav1.2 and voltage-activated potassium currents, including delayed rectifier, noise-like and transient outward currents. However, expression of channel proteins, such as sodium channel Nav1.6 and potassium channels Kv1.2 and Kv1.3, were upregulated. Consistently, their potassium currents were also enhanced in the differentiated cells. CONCLUSION hBMSCs possess of great potential to differentiate into functional neurons, indicating that hBMSCs may be an ideal cell source in managing a variety of clinical diseases such as spinal cord injury.
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Gu C, Barry J. Function and mechanism of axonal targeting of voltage-sensitive potassium channels. Prog Neurobiol 2011; 94:115-32. [PMID: 21530607 DOI: 10.1016/j.pneurobio.2011.04.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 03/22/2011] [Accepted: 04/01/2011] [Indexed: 12/20/2022]
Abstract
Precise localization of various ion channels into proper subcellular compartments is crucial for neuronal excitability and synaptic transmission. Axonal K(+) channels that are activated by depolarization of the membrane potential participate in the repolarizing phase of the action potential, and hence regulate action potential firing patterns, which encode output signals. Moreover, some of these channels can directly control neurotransmitter release at axonal terminals by constraining local membrane excitability and limiting Ca(2+) influx. K(+) channels differ not only in biophysical and pharmacological properties, but in expression and subcellular distribution as well. Importantly, proper targeting of channel proteins is a prerequisite for electrical and chemical functions of axons. In this review, we first highlight recent studies that demonstrate different roles of axonal K(+) channels in the local regulation of axonal excitability. Next, we focus on research progress in identifying axonal targeting motifs and machinery of several different types of K(+) channels present in axons. Regulation of K(+) channel targeting and activity may underlie a novel form of neuronal plasticity. This research field can contribute to generating novel therapeutic strategies through manipulating neuronal excitability in treating neurological diseases, such as multiple sclerosis, neuropathic pain, and Alzheimer's disease.
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Affiliation(s)
- Chen Gu
- Department of Neuroscience and Center for Molecular Neurobiology, The Ohio State University, Columbus, USA.
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35
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Abstract
Axons are generally considered as reliable transmission cables in which stable propagation occurs once an action potential is generated. Axon dysfunction occupies a central position in many inherited and acquired neurological disorders that affect both peripheral and central neurons. Recent findings suggest that the functional and computational repertoire of the axon is much richer than traditionally thought. Beyond classical axonal propagation, intrinsic voltage-gated ionic currents together with the geometrical properties of the axon determine several complex operations that not only control signal processing in brain circuits but also neuronal timing and synaptic efficacy. Recent evidence for the implication of these forms of axonal computation in the short-term dynamics of neuronal communication is discussed. Finally, we review how neuronal activity regulates both axon morphology and axonal function on a long-term time scale during development and adulthood.
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Affiliation(s)
- Dominique Debanne
- Institut National de la Santé et de la Recherche Médicale U.641 and Université de la Méditerranée, Faculté de Médecine Secteur Nord, Marseille, France
| | - Emilie Campanac
- Institut National de la Santé et de la Recherche Médicale U.641 and Université de la Méditerranée, Faculté de Médecine Secteur Nord, Marseille, France
| | - Andrzej Bialowas
- Institut National de la Santé et de la Recherche Médicale U.641 and Université de la Méditerranée, Faculté de Médecine Secteur Nord, Marseille, France
| | - Edmond Carlier
- Institut National de la Santé et de la Recherche Médicale U.641 and Université de la Méditerranée, Faculté de Médecine Secteur Nord, Marseille, France
| | - Gisèle Alcaraz
- Institut National de la Santé et de la Recherche Médicale U.641 and Université de la Méditerranée, Faculté de Médecine Secteur Nord, Marseille, France
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Boudkkazi S, Fronzaroli-Molinieres L, Debanne D. Presynaptic action potential waveform determines cortical synaptic latency. J Physiol 2011; 589:1117-31. [PMID: 21224227 DOI: 10.1113/jphysiol.2010.199653] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Synaptic latency at cortical synapses is determined by the presynaptic release probability (Pr). Short- and long-term presynaptic plasticity is associated with modulation of synaptic delay. We show here that the duration and amplitude of the presynaptic action potential also determine synaptic latency at neocortical and hippocampal excitatory synapses. Blockade of voltage-gated potassium (Kv) channels with 4-aminopyridine or dendrotoxin-I, but not tetraethylammonium, induced a 1–2 ms shift in latency at excitatory synaptic connections formed by pairs of neocortical pyramidal neurons. 4-Aminopyridine or dendrotoxin-I, but not tetraethylammonium, increased the duration of the action potential recorded in the axon, suggesting that presynaptic spike duration is controlled by axonal Kv1 potassium channels. Spike width-dependent changes in latency have been identified at the mossy fibre–CA3 cell synapses and contribute to stabilization of synaptic timing during repetitive stimulation. The effects of presynaptic spike amplitude on synaptic latency were also examined. Decreasing the amplitude of the presynaptic action potential with 15–30 nm TTX reduced synaptic latency by ∼0.5 ms. The regulation of synaptic timing by potassium and sodium channel blockers could not be attributed to modulation of axonal conduction. Rather, these effects are compatible with modifications of the kinetics of the presynaptic calcium current. We conclude that synaptic latency at cortical neurons is not constant but dynamically regulated by presynaptic action potential waveform.
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Chen R, Li YJ, Li JQ, Lv XX, Chen SZ, Li WZ, Feng J, Li XY. Electrical injury alters ion channel expression levels and electrophysiological properties in rabbit dorsal root ganglia neurons. Burns 2010; 37:304-11. [PMID: 21074329 DOI: 10.1016/j.burns.2010.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 08/12/2010] [Accepted: 08/19/2010] [Indexed: 02/02/2023]
Abstract
The electrophysiological and morphological changes of nerve fibers induced by electrical injury have been widely addressed. However, the changes of ion channels in neurons after electrical shocks have not been systematically investigated yet. In this study, the sciatic nerves of rabbit were injured by 50 V 50 Hz, 110 V 50 Hz, and 220 V 50 Hz alternating current, respectively. One week later, the expression levels and electrophysiological changes of voltage-gated potassium (Kv) and sodium (Nav) channels in dorsal root ganglia (DRG) neurons were evaluated by RT-PCR, immunofluorescence staining and patch clamp technique. The Nav1.1 expression was decreased by 50V injury. The Kv1.2, Kv1.4, Nav1.1 and Nav1.7 expression levels and Kv current densities were reduced after 110 V injury. Under the 220 V injury circumstance, Kv1.2, Nav1.1, Nav1.7 expression levels, Kv current densities and TTX-R Na(+) current densities were significantly decreased, while TTX-S Na(+) current densities increased. These findings suggest that the expression levels, subunit compositions, and electrophysiological properties of Kv and Nav channels are altered after electrical injury, and the severity of injury gets worse as injury voltage increases.
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Affiliation(s)
- Rui Chen
- Department of Burn and Plastic Surgery, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China
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38
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Dynamic and specific interaction between synaptic NR2-NMDA receptor and PDZ proteins. Proc Natl Acad Sci U S A 2010; 107:19561-6. [PMID: 20974938 DOI: 10.1073/pnas.1002690107] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The relative content of NR2 subunits in the NMDA receptor confers specific signaling properties and plasticity to synapses. However, the mechanisms that dynamically govern the retention of synaptic NMDARs, in particular 2A-NMDARs, remain poorly understood. Here, we investigate the dynamic interaction between NR2 C termini and proteins containing PSD-95/Discs-large/ZO-1 homology (PDZ) scaffold proteins at the single molecule level by using high-resolution imaging. We report that a biomimetic divalent competing ligand, mimicking the last 15 amino acids of NR2A C terminus, specifically and efficiently disrupts the interaction between 2A-NMDARs, but not 2B-NMDARs, and PDZ proteins on the time scale of minutes. Furthermore, displacing 2A-NMDARs out of synapses lead to a compensatory increase in synaptic NR2B-NMDARs, providing functional evidence that the anchoring mechanism of 2A- or 2B-NMDARs is different. These data reveal an unexpected role of the NR2 subunit divalent arrangement in providing specific anchoring within synapses, highlighting the need to study such dynamic interactions in native conditions.
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Luján R. Organisation of potassium channels on the neuronal surface. J Chem Neuroanat 2010; 40:1-20. [PMID: 20338235 DOI: 10.1016/j.jchemneu.2010.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 03/10/2010] [Accepted: 03/11/2010] [Indexed: 11/30/2022]
Abstract
Potassium channels are a family of ion channels that govern the intrinsic electrical properties of neurons in the brain. Molecular cloning has revealed over 100 genes encoding the pore-forming alpha subunits of potassium channels in mammals, making them the most diverse subset of ion channels. Multiplicity in this ion channel family is further generated through alternative splicing. The precise location of potassium channels along the dendro-somato-axonic surface of the neurons is an important factor in determining its functional impact. Today, it is widely accepted that potassium channels can be located at any subcellular compartment on the neuronal surface, at synaptic and extrasynaptic sites, from somata to dendritic shafts, dendritic spines, axons or axon terminals. However, they are not evenly distributed on the neuronal surface and depending on the potassium channel subtype, are instead concentrated at different compartments. This selective localization of ion channels to specific neuronal compartments has many different functional implications. One factor necessary to understand the role of potassium channels in neuronal function is to unravel their specialized distribution and subcellular localization within a cell, and this can only be achieved by electron microscopy. In this review, I summarize anatomical findings, describing their distribution in the central nervous system. The distinct regional, cellular and subcellular distribution of potassium channels in the brain will be discussed in view of their possible functional implications.
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Affiliation(s)
- Rafael Luján
- Departamento de Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02006 Albacete, Spain.
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40
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Age-dependent axonal expression of potassium channel proteins during development in mouse hippocampus. Histochem Cell Biol 2009; 133:301-12. [DOI: 10.1007/s00418-009-0668-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
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Hu D, Liu J, Xiong H. Enhancement of neuronal outward delayed rectifier K+ current by human monocyte-derived macrophages. Glia 2009; 57:1492-500. [PMID: 19306367 DOI: 10.1002/glia.20865] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Macrophages are critical cells in mediating the pathology of neurodegenerative disorders and enhancement of neuronal outward potassium (K(+)) current has implicated in neuronal apoptosis. To understand how activated macrophages induce neuronal dysfunction and injury, we studied the effects of lipopolysaccharide (LPS)-stimulated human monocytes-derived macrophage (MDM) on neuronal outward delayed rectifier K(+) current (I(K)) and resultant change on neuronal viability in primary rat hippocampal neuronal culture. Bath application of LPS-stimulated MDM-conditioned media (MCM) enhanced neuronal I(K) in a concentration-dependent manner, whereas non-stimulated MCM failed to alter neuronal I(K). The enhancement of neuronal I(K) was repeated in a macrophage-neuronal co-culture system. The link of stimulated MCM (MCM(+))-associated enhancement of I(K) to MCM(+)-induced neuronal injury, as detected by PI/DAPI (propidium iodide/4',6-diamidino-2-phenylindol) staining and MTT assay, was demonstrated by experimental results showing that addition of I(K) blocker tetraethylammonium to the culture protected hippocampal neurons from MCM(+)-associated challenge. Further investigation revealed elevated levels of K(v) 1.3 and K(v) 1.5 channel expression in hippocampal neurons after addition of MCM(+) to the culture. These results suggest that during brain inflammation macrophages, through their capacity of releasing bioactive molecules, induce neuronal injury by enhancing neuronal I(K) and that modulation of K(v) channels is a new approach to neuroprotection.
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Affiliation(s)
- Dehui Hu
- Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska 68198-5880, USA
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Arrested maturation of excitatory synapses in autosomal dominant lateral temporal lobe epilepsy. Nat Med 2009; 15:1208-14. [PMID: 19701204 PMCID: PMC2759408 DOI: 10.1038/nm.2019] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 07/28/2009] [Indexed: 02/08/2023]
Abstract
A subset of central glutamatergic synapses are coordinatelypruned and matured by unresolved mechanisms during early postnatal life. We report that human epilepsy gene LGI1, mutated in autosomal dominant lateral temporal lobe epilepsy (ADLTE), mediates this process in hippocampus. We introduced full-length genes encoding (1) ADLTE truncated mutant LGI1 (835delC) and (2) excess wild-type LGI1 proteins into transgenic mice. We discovered that the normal postnatal Kv1 channel-dependent down-regulation of presynaptic release probability and Src kinase-related decrease of postsynaptic NR2B/NR2A ratio were arrested by ADLTE mutant LGI1, and contrastingly, were magnified by excess wild-type LGI1. Concurrently, mutant LGI1 inhibited dendritic pruning and increased the spine density to markedly increase excitatory transmission. Inhibitory transmission, by contrast, was unaffected. Furthermore, mutant LGI1 promoted epileptiform discharge in vitro and kindling epileptogenesis in vivo with partial GABAA receptor blockade. Thus, LGI1 represents the first human gene mutated to promote epilepsy through impaired glutamatergic circuit maturation.
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Stirling L, Williams MR, Morielli AD. Dual roles for RHOA/RHO-kinase in the regulated trafficking of a voltage-sensitive potassium channel. Mol Biol Cell 2009; 20:2991-3002. [PMID: 19403695 DOI: 10.1091/mbc.e08-10-1074] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Kv1.2 is a member of the Shaker family of voltage-sensitive potassium channels and contributes to regulation of membrane excitability. The electrophysiological activity of Kv1.2 undergoes tyrosine kinase-dependent suppression in a process involving RhoA. We report that RhoA elicits suppression of Kv1.2 ionic current by modulating channel endocytosis. This occurs through two distinct pathways, one clathrin-dependent and the other cholesterol-dependent. Activation of Rho kinase (ROCK) via the lysophosphatidic acid (LPA) receptor elicits clathrin-dependent Kv1.2 endocytosis and consequent attenuation of its ionic current. LPA-induced channel endocytosis is blocked by the ROCK inhibitor Y27632 or by clathrin RNA interference. In contrast, steady-state endocytosis of Kv1.2 in unstimulated cells is cholesterol dependent. Inhibition of basal ROCK signaling with Y27632 increased surface Kv1.2, an effect that persists in the presence of clathrin small interfering RNA and that is not additive to the increase in surface channel levels elicited by the cholesterol sequestering drug filipin. Temperature block experiments show that ROCK affects cholesterol-dependent trafficking by modulating the recycling of endocytosed channel back to the plasma membrane. Both receptor-stimulated and steady-state Kv1.2 trafficking modulated by RhoA/ROCK required the activation of dynamin as well as the ROCK effector Lim-kinase, indicating a key role for actin remodeling in RhoA-dependent Kv1.2 regulation.
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Affiliation(s)
- Lee Stirling
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA
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Bender RA, Baram TZ. Hyperpolarization activated cyclic-nucleotide gated (HCN) channels in developing neuronal networks. Prog Neurobiol 2008; 86:129-40. [PMID: 18834920 PMCID: PMC2606691 DOI: 10.1016/j.pneurobio.2008.09.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 07/24/2008] [Accepted: 09/04/2008] [Indexed: 12/23/2022]
Abstract
Developing neuronal networks evolve continuously, requiring that neurons modulate both their intrinsic properties and their responses to incoming synaptic signals. Emerging evidence supports roles for the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in this neuronal plasticity. HCN channels seem particularly suited for fine-tuning neuronal properties and responses because of their remarkably large and variable repertoire of functions, enabling integration of a wide range of cellular signals. Here, we discuss the involvement of HCN channels in cortical and hippocampal network maturation, and consider potential roles of developmental HCN channel dysregulation in brain disorders such as epilepsy.
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Affiliation(s)
- Roland A. Bender
- Institute of Anatomy I, University of Hamburg, D-20246 Hamburg, Germany, Phone: +49-40-428034333, Fax: +49-40-428034966, E-mail:
| | - Tallie Z. Baram
- Departments Anatomy/Neurobiology, Pediatrics & Neurology, University of California, Irvine, CA 92697-4475, USA, Phone: +1-949-824-3307, Fax: +1-949-824-1106, E-mail:
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Okada M, Matsuda H. Chronic lentiviral expression of inwardly rectifying K+ channels (Kir2.1) reduces neuronal activity and downregulates voltage-gated potassium currents in hippocampus. Neuroscience 2008; 156:289-97. [PMID: 18713648 DOI: 10.1016/j.neuroscience.2008.07.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 06/19/2008] [Accepted: 07/17/2008] [Indexed: 10/21/2022]
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McKeown L, Swanton L, Robinson P, Jones OT. Surface expression and distribution of voltage-gated potassium channels in neurons (Review). Mol Membr Biol 2008; 25:332-43. [PMID: 18446619 DOI: 10.1080/09687680801992470] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The last decade has witnessed an exponential increase in interest in one of the great mysteries of nerve cell biology: Specifically, how do neurons know where to place the ion channels that control their excitability? Many of the most important insights have been gleaned from studies on the voltage-gated potassium channels (Kvs) which underlie the shape, duration and frequency of action potentials. In this review, we gather recent evidence on the expression, trafficking and maintenance mechanisms which control the surface density of Kvs in different subcellular compartments of neurons and how these may be regulated to control cell excitability.
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Affiliation(s)
- Lynn McKeown
- Faculty of Life Sciences, The University of Manchester, Manchester, UK
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Ribeiro PAO, Sbragia L, Gilioli R, Langone F, Conte FF, Lopes-Cendes I. Expression profile of Lgi1 gene in mouse brain during development. J Mol Neurosci 2008; 35:323-9. [PMID: 18563303 DOI: 10.1007/s12031-008-9096-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 04/28/2008] [Indexed: 11/29/2022]
Abstract
Mutations in LGI1 were described in patients with autosomal dominant partial epilepsy with auditory features (ADPEAF), and recent clinical findings have implicated LGI1 in human brain development. However, the precise role of LGI1 in epileptogenesis remains largely unknown. The objective of this study was to determine the expression pattern of Lgi1 in mice brain during development and in adult animals. Real-time polymerase chain reaction (PCR) quantification and Western blot experiments showed a relative low expression during intrauterine stages, increasing until adulthood. In addition, we did not find significant differences between left and right hemispheres. The hippocampus presented higher levels of Lgi1 expression when compared to the neocortex and the cerebellum of adult animals; however, these results did not reach statistical significance. This study was the first to determine a specific profile of Lgi1 gene expression during central nervous system development, which suggests a possible inhibitory function in latter stages of development. In addition, we did not find differences in hemispheric expression that could explain the predominance of left-sided abnormalities in patients with ADPEAF.
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Affiliation(s)
- Patrícia A O Ribeiro
- Department of Medical Genetics, University of Campinas, Campinas, São Paulo, Brazil
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Standard antiepileptic drugs fail to block epileptiform activity in rat organotypic hippocampal slice cultures. Br J Pharmacol 2008; 154:709-24. [PMID: 18414393 DOI: 10.1038/bjp.2008.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Earlier studies had demonstrated that tonic-clonic seizure-like events (SLEs) resembling electrographic correlates of limbic seizures in animals and humans can be induced in organotypic hippocampal slice cultures (OHSCs). We have explored OHSCs for their suitability to serve as in vitro models of limbic seizures for studying seizure mechanisms and screening new antiepileptic compounds. EXPERIMENTAL APPROACH OHSCs were cultivated according to the interface method. Neuronal activity and extracellular potassium concentration were recorded under submerged conditions. SLEs were induced by lowering magnesium concentration or by applying the potassium channel blocker 4-aminopyridine. The effects of standard antiepileptic drugs (AEDs), carbamazepine, phenytoin, valproic acid, clonazepam, diazepam and phenobarbital sodium on SLEs were analysed. KEY RESULTS In more than 93% of OHSCs, AEDs did not prevent the induction of SLEs or stop ongoing seizure activity even when toxic concentrations were applied. This pharmacoresistance was independent of the method of seizure provocation, postnatal age at explantation (P2-P10) and cultivation time in vitro (2 months). SLEs were reversibly blocked by glutamate antagonists or the GABA(A)-agonist muscimol. CONCLUSIONS AND IMPLICATIONS We present a simple to establish in vitro model of tonic-clonic SLEs that is a priori pharmacoresistant and thus has an advantage over animal models of pharmacoresistant seizures in which responders and non-responders can be sorted out only after an experiment. OHSCs could be suitable for exploring mechanisms of pharmacoresistant seizures and be used for the identification of new anticonvulsive compounds eventually effective in drug refractory epilepsy.
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Martin S, Wilkinson KA, Nishimune A, Henley JM. Emerging extranuclear roles of protein SUMOylation in neuronal function and dysfunction. Nat Rev Neurosci 2007; 8:948-59. [PMID: 17987030 PMCID: PMC3314512 DOI: 10.1038/nrn2276] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Post-translational protein modifications are integral components of signalling cascades that enable cells to efficiently, rapidly and reversibly respond to extracellular stimuli. These modifications have crucial roles in the CNS, where the communication between neurons is particularly complex. SUMOylation is a post-translational modification in which a member of the small ubiquitin-like modifier (SUMO) family of proteins is conjugated to lysine residues in target proteins. It is well established that SUMOylation controls many aspects of nuclear function, but it is now clear that it is also a key determinant in many extranuclear neuronal processes, and it has also been implicated in a wide range of neuropathological conditions.
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Affiliation(s)
- Stéphane Martin
- MRC Centre for Synaptic Plasticity, Department of Anatomy, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, UK
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Wenzel HJ, Vacher H, Clark E, Trimmer JS, Lee AL, Sapolsky RM, Tempel BL, Schwartzkroin PA. Structural consequences of Kcna1 gene deletion and transfer in the mouse hippocampus. Epilepsia 2007; 48:2023-46. [PMID: 17651419 PMCID: PMC2752664 DOI: 10.1111/j.1528-1167.2007.01189.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
PURPOSE Mice lacking the Kv1.1 potassium channel alpha subunit encoded by the Kcna1 gene develop recurrent behavioral seizures early in life. We examined the neuropathological consequences of seizure activity in the Kv1.1(-/-) (knock-out) mouse, and explored the effects of injecting a viral vector carrying the deleted Kcna1 gene into hippocampal neurons. METHODS Morphological techniques were used to assess neuropathological patterns in hippocampus of Kv1.1(-/-) animals. Immunohistochemical and biochemical techniques were used to monitor ion channel expression in Kv1.1(-/-) brain. Both wild-type and knockout mice were injected (bilaterally into hippocampus) with an HSV1 amplicon vector that contained the rat Kcna1 subunit gene and/or the E. coli lacZ reporter gene. Vector-injected mice were examined to determine the extent of neuronal infection. RESULTS Video/EEG monitoring confirmed interictal abnormalities and seizure occurrence in Kv1.1(-/-) mice. Neuropathological assessment suggested that hippocampal damage (silver stain) and reorganization (Timm stain) occurred only after animals had exhibited severe prolonged seizures (status epilepticus). Ablation of Kcna1 did not result in compensatory changes in expression levels of other related ion channel subunits. Vector injection resulted in infection primarily of granule cells in hippocampus, but the number of infected neurons was quite variable across subjects. Kcna1 immunocytochemistry showed "ectopic" Kv1.1 alpha channel subunit expression. CONCLUSIONS Kcna1 deletion in mice results in a seizure disorder that resembles--electrographically and neuropathologically--the patterns seen in rodent models of temporal lobe epilepsy. HSV1 vector-mediated gene transfer into hippocampus yielded variable neuronal infection.
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Affiliation(s)
- H. Jürgen Wenzel
- Department of Neurological Surgery, School of Medicine, University of California, Davis, CA
| | - Helene Vacher
- Department of Pharmacology, School of Medicine, University of California, Davis, CA
| | - Eliana Clark
- Department of Pharmacology, School of Medicine, University of California, Davis, CA
| | - James S. Trimmer
- Department of Pharmacology, School of Medicine, University of California, Davis, CA
| | - Angela L. Lee
- Department of Biological Sciences, Stanford University, Stanford, CA
| | | | - Bruce L Tempel
- Departments of Otolaryngology and Pharmacology, School of Medicine, University of Washington, Seattle, WA
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