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Hernández-Morales M, Morales-Weil K, Han SM, Han V, Tran T, Benner EJ, Pegram K, Meanor J, Miller EW, Kramer RH, Liu C. Electrophysiological Mechanisms and Validation of Ferritin-Based Magnetogenetics for Remote Control of Neurons. J Neurosci 2024; 44:e1717232024. [PMID: 38777598 PMCID: PMC11270515 DOI: 10.1523/jneurosci.1717-23.2024] [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: 09/07/2023] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024] Open
Abstract
Magnetogenetics was developed to remotely control genetically targeted neurons. A variant of magnetogenetics uses magnetic fields to activate transient receptor potential vanilloid (TRPV) channels when coupled with ferritin. Stimulation with static or RF magnetic fields of neurons expressing these channels induces Ca2+ transients and modulates behavior. However, the validity of ferritin-based magnetogenetics has been questioned due to controversies surrounding the underlying mechanisms and deficits in reproducibility. Here, we validated the magnetogenetic approach Ferritin-iron Redistribution to Ion Channels (FeRIC) using electrophysiological (Ephys) and imaging techniques. Previously, interference from RF stimulation rendered patch-clamp recordings inaccessible for magnetogenetics. We solved this limitation for FeRIC, and we studied the bioelectrical properties of neurons expressing TRPV4 (nonselective cation channel) and transmembrane member 16A (TMEM16A; chloride-permeable channel) coupled to ferritin (FeRIC channels) under RF stimulation. We used cultured neurons obtained from the rat hippocampus of either sex. We show that RF decreases the membrane resistance (Rm) and depolarizes the membrane potential in neurons expressing TRPV4FeRIC RF does not directly trigger action potential firing but increases the neuronal basal spiking frequency. In neurons expressing TMEM16AFeRIC, RF decreases the Rm, hyperpolarizes the membrane potential, and decreases the spiking frequency. Additionally, we corroborated the previously described biochemical mechanism responsible for RF-induced activation of ferritin-coupled ion channels. We solved an enduring problem for ferritin-based magnetogenetics, obtaining direct Ephys evidence of RF-induced activation of ferritin-coupled ion channels. We found that RF does not yield instantaneous changes in neuronal membrane potentials. Instead, RF produces responses that are long-lasting and moderate, but effective in controlling the bioelectrical properties of neurons.
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Affiliation(s)
- Miriam Hernández-Morales
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
| | - Koyam Morales-Weil
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
| | - Sang Min Han
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
| | - Victor Han
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
| | - Tiffany Tran
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
| | - Eric J Benner
- Division of Neonatology, Department of Pediatrics, Duke University Medical Center, Jean and George Brumley, Jr. Neonatal-Perinatal Institute, Durham, North Carolina 27710
| | - Kelly Pegram
- Division of Neonatology, Department of Pediatrics, Duke University Medical Center, Jean and George Brumley, Jr. Neonatal-Perinatal Institute, Durham, North Carolina 27710
| | - Jenna Meanor
- Division of Neonatology, Department of Pediatrics, Duke University Medical Center, Jean and George Brumley, Jr. Neonatal-Perinatal Institute, Durham, North Carolina 27710
| | - Evan W Miller
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
- Department of Chemistry, University of California, Berkeley, California 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Chunlei Liu
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720
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Li K, Guo Y, Wang Y, Zhu R, Chen W, Cheng T, Zhang X, Jia Y, Liu T, Zhang W, Jan LY, Jan YN. Drosophila TMEM63 and mouse TMEM63A are lysosomal mechanosensory ion channels. Nat Cell Biol 2024; 26:393-403. [PMID: 38388853 PMCID: PMC10940159 DOI: 10.1038/s41556-024-01353-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 01/10/2024] [Indexed: 02/24/2024]
Abstract
Cells sense physical forces and convert them into electrical or chemical signals, a process known as mechanotransduction. Whereas extensive studies focus on mechanotransduction at the plasma membrane, little is known about whether and how intracellular organelles sense mechanical force and the physiological functions of organellar mechanosensing. Here we identify the Drosophila TMEM63 (DmTMEM63) ion channel as an intrinsic mechanosensor of the lysosome, a major degradative organelle. Endogenous DmTMEM63 proteins localize to lysosomes, mediate lysosomal mechanosensitivity and modulate lysosomal morphology and function. Tmem63 mutant flies exhibit impaired lysosomal degradation, synaptic loss, progressive motor deficits and early death, with some of these mutant phenotypes recapitulating symptoms of TMEM63-associated human diseases. Importantly, mouse TMEM63A mediates lysosomal mechanosensitivity in Neuro-2a cells, indicative of functional conservation in mammals. Our findings reveal DmTMEM63 channel function in lysosomes and its physiological roles in vivo and provide a molecular basis to explore the mechanosensitive process in subcellular organelles.
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Affiliation(s)
- Kai Li
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Yanmeng Guo
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Yayu Wang
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Ruijun Zhu
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Wei Chen
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Tong Cheng
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Xiaofan Zhang
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Yinjun Jia
- School of Life Sciences, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Ting Liu
- School of Life Sciences, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Wei Zhang
- School of Life Sciences, Tsinghua-Peking Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Lily Yeh Jan
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA
| | - Yuh Nung Jan
- Department of Physiology, University of California at San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, CA, USA.
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3
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Griffis KG, Fehlhaber KE, Rieke F, Sampath AP. Light Adaptation of Retinal Rod Bipolar Cells. J Neurosci 2023; 43:4379-4389. [PMID: 37208176 PMCID: PMC10278674 DOI: 10.1523/jneurosci.0444-23.2023] [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: 03/10/2023] [Revised: 04/07/2023] [Accepted: 05/02/2023] [Indexed: 05/21/2023] Open
Abstract
The sensitivity of retinal cells is altered in background light to optimize the detection of contrast. For scotopic (rod) vision, substantial adaptation occurs in the first two cells, the rods and rod bipolar cells (RBCs), through sensitivity adjustments in rods and postsynaptic modulation of the transduction cascade in RBCs. To study the mechanisms mediating these components of adaptation, we made whole-cell, voltage-clamp recordings from retinal slices of mice from both sexes. Adaptation was assessed by fitting the Hill equation to response-intensity relationships with the parameters of half-maximal response (I1/2 ), Hill coefficient (n), and maximum response amplitude (Rmax ). We show that rod sensitivity decreases in backgrounds according to the Weber-Fechner relation with an I1/2 of ∼50 R* s-1 The sensitivity of RBCs follows a near-identical function, indicating that changes in RBC sensitivity in backgrounds bright enough to adapt the rods are mostly derived from the rods themselves. Backgrounds too dim to adapt the rods can however alter n, relieving a synaptic nonlinearity likely through entry of Ca2+ into the RBCs. There is also a surprising decrease of Rmax , indicating that a step in RBC synaptic transduction is desensitized or that the transduction channels became reluctant to open. This effect is greatly reduced after dialysis of BAPTA at a membrane potential of +50 mV to impede Ca2+ entry. Thus the effects of background illumination in RBCs are in part the result of processes intrinsic to the photoreceptors and in part derive from additional Ca2+-dependent processes at the first synapse of vision.SIGNIFICANCE STATEMENT Light adaptation adjusts the sensitivity of vision as ambient illumination changes. Adaptation for scotopic (rod) vision is known to occur partly in the rods and partly in the rest of the retina from presynaptic and postsynaptic mechanisms. We recorded light responses of rods and rod bipolar cells to identify different components of adaptation and study their mechanisms. We show that bipolar-cell sensitivity largely follows adaptation of the rods but that light too dim to adapt the rods produces a linearization of the bipolar-cell response and a surprising decrease in maximum response amplitude, both mediated by a change in intracellular Ca2+ These findings provide a new understanding of how the retina responds to changing illumination.
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Affiliation(s)
- Khris G Griffis
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, California 90095
| | - Katherine E Fehlhaber
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
| | - Alapakkam P Sampath
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
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Beltrán-Matas P, Hartveit E, Veruki ML. Functional properties of GABA A receptors of AII amacrine cells of the rat retina. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1134765. [PMID: 38983040 PMCID: PMC11182327 DOI: 10.3389/fopht.2023.1134765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 03/08/2023] [Indexed: 07/11/2024]
Abstract
Amacrine cells are a highly diverse group of inhibitory retinal interneurons that sculpt the responses of bipolar cells, ganglion cells, and other amacrine cells. They integrate excitatory inputs from bipolar cells and inhibitory inputs from other amacrine cells, but for most amacrine cells, little is known about the specificity and functional properties of their inhibitory inputs. Here, we have investigated GABAA receptors of the AII amacrine, a critical neuron in the rod pathway microcircuit, using patch-clamp recording in rat retinal slices. Puffer application of GABA evoked robust responses, but, surprisingly, spontaneous GABAA receptor-mediated postsynaptic currents were not observed, neither under control conditions nor following application of high-K+ solution to facilitate release. To investigate the biophysical and pharmacological properties of GABAA receptors in AIIs, we therefore used nucleated patches and a fast application system. Both brief and long pulses of GABA (3 mM) evoked GABAA receptor-mediated currents with slow, multi-exponential decay kinetics. The average weighted time constant (τw) of deactivation was ~163 ms. Desensitization was even slower, with τw ~330 ms. Non-stationary noise analysis of patch responses and directly observed channel gating yielded a single-channel conductance of ~23 pS. Pharmacological investigation suggested the presence of α2 and/or α3 subunits, as well as the γ2 subunit. Such subunit combinations are typical of GABAA receptors with slow kinetics. If synaptic GABAA receptors of AII amacrines have similar functional properties, the slow deactivation and desensitization kinetics will facilitate temporal summation of GABAergic inputs, allowing effective summation and synaptic integration to occur even for relatively low frequencies of inhibitory inputs.
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Affiliation(s)
| | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
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5
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Jain A, Woolley CS. Mechanisms That Underlie Expression of Estradiol-Induced Excitatory Synaptic Potentiation in the Hippocampus Differ between Males and Females. J Neurosci 2023; 43:1298-1309. [PMID: 36650060 PMCID: PMC9987570 DOI: 10.1523/jneurosci.2080-19.2023] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/19/2023] Open
Abstract
17β-estradiol (E2) is synthesized in the hippocampus of both sexes and acutely potentiates excitatory synapses in each sex. Previously, we found that the mechanisms for initiation of E2-induced synaptic potentiation differ between males and females, including in the molecular signaling involved. Here, we used electrical stimulation and two-photon glutamate uncaging in hippocampal slices from adult male and female rats to investigate whether the downstream consequences of distinct molecular signaling remain different between the sexes or converge to the same mechanism(s) of expression of potentiation. This showed that synaptic activity is necessary for expression of E2-induced potentiation in females but not males, which paralleled a sex-specific requirement in females for calcium-permeable AMPARs (cpAMPARs) to stabilize potentiation. Nonstationary fluctuation analysis of two-photon evoked unitary synaptic currents showed that the postsynaptic component of E2-induced potentiation occurs either through an increase in AMPAR conductance or in nonconductive properties of AMPARs (number of channels × open probability) and never both at the same synapse. In females, most synapses (76%) were potentiated via increased AMPAR conductance, whereas in males, more synapses (60%) were potentiated via an increase in nonconductive AMPAR properties. Inhibition of cpAMPARs eliminated E2-induced synaptic potentiation in females, whereas some synapses in males were unaffected by cpAMPAR inhibition; these synapses in males potentiated exclusively via increased AMPAR nonconductive properties. This sex bias in expression mechanisms of E2-induced synaptic potentiation underscores the concept of latent sex differences in mechanisms of synaptic plasticity in which the same outcome in each sex is achieved through distinct underlying mechanisms.SIGNIFICANCE STATEMENT Estrogens are synthesized in the brains of both sexes and potentiate excitatory synapses to the same degree in each sex. Despite this apparent similarity, the molecular signaling that initiates estrogen-induced synaptic potentiation differs between the sexes. Here we show that these differences extend to the mechanisms of expression of synaptic potentiation and result in distinct patterns of postsynaptic neurotransmitter receptor modulation in each sex. Such latent sex differences, in which the same outcome is achieved through distinct underlying mechanisms in males versus females, indicate that molecular mechanisms targeted for drug development may differ between the sexes even in the absence of an overt sex difference in behavior or disease.
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Affiliation(s)
- Anant Jain
- Department of Neurobiology, Northwestern University, Evanston, Illinois 60208
| | - Catherine S Woolley
- Department of Neurobiology, Northwestern University, Evanston, Illinois 60208
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6
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Zhou L, Wang K, Xu Y, Dong BB, Wu DC, Wang ZX, Wang XT, Cai XY, Yang JT, Zheng R, Chen W, Shen Y, Wei JS. A patient-derived mutation of epilepsy-linked LGI1 increases seizure susceptibility through regulating K v1.1. Cell Biosci 2023; 13:34. [PMID: 36804022 PMCID: PMC9940402 DOI: 10.1186/s13578-023-00983-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 02/04/2023] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND Autosomal dominant lateral temporal epilepsy (ADLTE) is an inherited syndrome caused by mutations in the leucine-rich glioma inactivated 1 (LGI1) gene. It is known that functional LGI1 is secreted by excitatory neurons, GABAergic interneurons, and astrocytes, and regulates AMPA-type glutamate receptor-mediated synaptic transmission by binding ADAM22 and ADAM23. However, > 40 LGI1 mutations have been reported in familial ADLTE patients, more than half of which are secretion-defective. How these secretion-defective LGI1 mutations lead to epilepsy is unknown. RESULTS We identified a novel secretion-defective LGI1 mutation from a Chinese ADLTE family, LGI1-W183R. We specifically expressed mutant LGI1W183R in excitatory neurons lacking natural LGI1, and found that this mutation downregulated Kv1.1 activity, led to neuronal hyperexcitability and irregular spiking, and increased epilepsy susceptibility in mice. Further analysis revealed that restoring Kv1.1 in excitatory neurons rescued the defect of spiking capacity, improved epilepsy susceptibility, and prolonged the life-span of mice. CONCLUSIONS These results describe a role of secretion-defective LGI1 in maintaining neuronal excitability and reveal a new mechanism in the pathology of LGI1 mutation-related epilepsy.
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Affiliation(s)
- Lin Zhou
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Kang Wang
- grid.452661.20000 0004 1803 6319Department of Neurology, First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, 310003 China
| | - Yuxiang Xu
- grid.256922.80000 0000 9139 560XSchool of Life Sciences, Henan University, Kaifeng, 475004 China
| | - Bin-Bin Dong
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Deng-Chang Wu
- grid.452661.20000 0004 1803 6319Department of Neurology, First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, 310003 China
| | - Zhao-Xiang Wang
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Xin-Tai Wang
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Xin-Yu Cai
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Jin-Tao Yang
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Rui Zheng
- grid.13402.340000 0004 1759 700XDepartment of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020 China
| | - Wei Chen
- Department of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020, China.
| | - Ying Shen
- Department of Physiology and Department of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310020, China.
| | - Jian-She Wei
- School of Life Sciences, Henan University, Kaifeng, 475004, China.
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Beltrán-Matas P, Castilho Á, Tencer B, Veruki ML, Hartveit E. Inhibitory inputs to an inhibitory interneuron: Spontaneous postsynaptic currents and GABA A receptors of A17 amacrine cells in the rat retina. Eur J Neurosci 2022; 55:1442-1470. [PMID: 35236011 PMCID: PMC9314042 DOI: 10.1111/ejn.15634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/29/2022]
Abstract
Amacrine cells constitute a large and heterogenous group of inhibitory interneurons in the retina. The A17 amacrine plays an important role for visual signaling in the rod pathway microcircuit of the mammalian retina. It receives excitatory input from rod bipolar cells and provides feedback inhibition to the same cells. However, from ultrastructural investigations, there is evidence for input to A17s from other types of amacrine cells, presumably inhibitory, but there is a lack of information about the identity and functional properties of the synaptic receptors and how inhibition contributes to the integrative properties of A17s. Here, we studied the biophysical and pharmacological properties of GABAergic spontaneous inhibitory postsynaptic currents (spIPSCs) and GABAA receptors of A17 amacrines, using whole-cell and outside-out patch recordings from rat retinal slices. The spIPSCs displayed fast onsets (10-90% rise time ~740 μs) and double-exponential decays (τfast ~4.5 ms [43% of amplitude]; τslow ~22 ms). Ultrafast application of brief pulses of GABA (3 mM) to patches evoked responses with deactivation kinetics best fitted by a triple-exponential function (τ1 ~5.3 ms [55% of amplitude]; τ2 ~48 ms [32% amplitude]; τ3 ~187 ms). Non-stationary noise analysis of spIPSCs and patch responses yielded single-channel conductances of ~21 and ~25 pS, respectively. Pharmacological analysis suggested that the spIPSCs are mediated by receptors with an α1βγ2 subunit composition and the somatic receptors have an α2βγ2 and/or α3βγ2 composition. These results demonstrate the presence of synaptic GABAA receptors on A17s, which may play an important role in signal integration in these cells.
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Affiliation(s)
| | - Áurea Castilho
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Barbora Tencer
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
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8
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Janach GMS, Böhm M, Döhne N, Kim HR, Rosário M, Strauss U. Interferon-γ enhances neocortical synaptic inhibition by promoting membrane association and phosphorylation of GABA A receptors in a protein kinase C-dependent manner. Brain Behav Immun 2022; 101:153-164. [PMID: 34998939 DOI: 10.1016/j.bbi.2022.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 12/11/2021] [Accepted: 01/03/2022] [Indexed: 12/16/2022] Open
Abstract
Interferon-γ (IFN-γ), an important mediator of the antiviral immune response, can also act as a neuromodulator. CNS IFN-γ levels rise acutely in response to infection and therapeutically applied IFN-γ provokes CNS related side effects. Moreover, IFN-γ plays a key role in neurophysiological processes and a variety of chronic neurological and neuropsychiatric conditions. To close the gap between basic research, behavioral implications and clinical applicability, knowledge of the mechanism behind IFN-γ related changes in brain function is crucial. Here, we studied the underlying mechanism of acutely augmented neocortical inhibition by IFN-γ (1.000 IU ml-1) in layer 5 pyramidal neurons of male Wistar rats. We demonstrate postsynaptic mediation of IFN-γ augmented inhibition by pressure application of GABA and analysis of paired pulse ratios. IFN-γ increases membrane presence of GABAAR γ2, as quantified by cell surface biotinylation and functional synaptic GABAAR number, as determined by peak-scaled non-stationary noise analysis. The increase in functional receptor number was comparable to the increase in underlying miniature inhibitory postsynaptic current (mIPSC) amplitudes. Blockage of putative intracellular mediators, namely phosphoinositide 3-kinase and protein kinase C (PKC) by Wortmannin and Calphostin C, respectively, revealed PKC-dependency of the pro-inhibitory IFN-γ effect. This was corroborated by increased serine phosphorylation of P-serine PKC motifs on GABAAR γ2 upon IFN-γ application. GABAAR single channel conductance, intracellular chloride levels and GABAAR driving force are unlikely to contribute to the effect, as shown by single channel recordings and chloride imaging. The effect of IFN-γ on mIPSC amplitudes was similar in female and male rats, suggesting a gender-independent mechanism of action. Collectively, these results indicate a novel mechanism for the regulation of inhibition by IFN-γ, which could impact on neocortical function and therewith behavior.
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Affiliation(s)
- Gabriel M S Janach
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Maximilian Böhm
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Noah Döhne
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Ha-Rang Kim
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux, France
| | - Marta Rosário
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany
| | - Ulf Strauss
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Cell Biology and Neurobiology, Charitéplatz 1, 10117 Berlin, Germany.
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9
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Kadgien CA, Kamesh A, Milnerwood AJ. Endosomal traffic and glutamate synapse activity are increased in VPS35 D620N mutant knock-in mouse neurons, and resistant to LRRK2 kinase inhibition. Mol Brain 2021; 14:143. [PMID: 34530877 PMCID: PMC8447518 DOI: 10.1186/s13041-021-00848-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 08/27/2021] [Indexed: 12/26/2022] Open
Abstract
Vacuolar protein sorting 35 (VPS35) regulates neurotransmitter receptor recycling from endosomes. A missense mutation (D620N) in VPS35 leads to autosomal-dominant, late-onset Parkinson's disease. Here, we study the basic neurobiology of VPS35 and Parkinson's disease mutation effects in the D620N knock-in mouse and the effect of leucine-rich repeat kinase 2 (LRRK2) inhibition on synaptic phenotypes. The study was conducted using a VPS35 D620N knock-in mouse that expresses VPS35 at endogenous levels. Protein levels, phosphorylation states, and binding ratios in brain lysates from knock-in mice and wild-type littermates were assayed by co-immunoprecipitation and western blot. Dendritic protein co-localization, AMPA receptor surface expression, synapse density, and glutamatergic synapse activity in primary cortical cultures from knock-in and wild-type littermates were assayed using immunocytochemistry and whole-cell patch clamp electrophysiology. In brain tissue, we confirm VPS35 forms complexes with LRRK2 and AMPA-type glutamate receptor GluA1 subunits, in addition to NMDA-type glutamate receptor GluN1 subunits and D2-type dopamine receptors. Receptor and LRRK2 binding was unaltered in D620N knock-in mice, but we confirm the mutation results in reduced binding of VPS35 with WASH complex member FAM21, and increases phosphorylation of the LRRK2 kinase substrate Rab10, which is reversed by LRRK2 kinase inhibition in vivo. In cultured cortical neurons from knock-in mice, pRab10 is also increased, and reversed by LRRK2 inhibition. The mutation also results in increased endosomal recycling protein cluster density (VPS35-FAM21 co-clusters and Rab11 clusters), glutamate transmission, and GluA1 surface expression. LRRK2 kinase inhibition, which reversed Rab10 hyper-phosphorylation, did not rescue elevated glutamate release or surface GluA1 expression in knock-in neurons, but did alter AMPAR traffic in wild-type cells. The results improve our understanding of the cell biology of VPS35, and the consequences of the D620N mutation in developing neuronal networks. Together the data support a chronic synaptopathy model for latent neurodegeneration, providing phenotypes and candidate pathophysiological stresses that may drive eventual transition to late-stage parkinsonism in VPS35 PD. The study demonstrates the VPS35 mutation has effects that are independent of ongoing LRRK2 kinase activity, and that LRRK2 kinase inhibition alters basal physiology of glutamate synapses in vitro.
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Affiliation(s)
- Chelsie A Kadgien
- Graduate Program in Neuroscience and Centre for Applied Neurogenetics, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
| | - Anusha Kamesh
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada
| | - Austen J Milnerwood
- Graduate Program in Neuroscience and Centre for Applied Neurogenetics, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.
- Montreal Neurological Institute-Hospital, McGill University, Montreal, Canada.
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10
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Kim KW, Suh BC. Ethanol inhibits Kv7.2/7.3 channel open probability by reducing the PI(4,5)P2 sensitivity of Kv7.2 subunit. BMB Rep 2021. [PMID: 33408002 PMCID: PMC8249878 DOI: 10.5483/bmbrep.2021.54.6.231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Ethanol often causes critical health problems by altering the neuro-nal activities of the central and peripheral nerve systems. One of the cellular targets of ethanol is the plasma membrane proteins including ion channels and receptors. Recently, we reported that ethanol elevates membrane excitability in sympathetic neurons by inhibiting Kv7.2/7.3 channels in a cell type-specific manner. Even though our studies revealed that the inhibitory effects of ethanol on the Kv7.2/7.3 channel was diminished by the increase of plasma membrane phosphatidylinositol 4,5-bisphosphate (PI (4,5)P2), the molecular mechanism of ethanol on Kv7.2/7.3 channel inhibition remains unclear. By investigating the kinetics of Kv7.2/7.3 current in high K+ solution, we found that ethanol inhibited Kv7.2/7.3 channels through a mechanism distinct from that of tetraethylammonium (TEA) which enters into the pore and blocks the gate of the channels. Using a non-stationary noise analysis (NSNA), we demonstrated that the inhibitory effect of ethanol is the result of reduction of open probability (PO) of the Kv7.2/7.3 channel, but not of a single channel current (i) or channel number (N). Finally, ethanol selectively facilitated the kinetics of Kv7.2 current suppression by voltage-sensing phosphatase (VSP)-induced PI(4,5)P2 depletion, while it slowed down Kv7.2 current recovery from the VSP-induced inhibition. Together our results suggest that ethanol regulates neuronal activity through the reduction of open probability and PI(4,5)P2 sensitivity of Kv7.2/7.3 channels.
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Affiliation(s)
- Kwon-Woo Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
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11
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Ko W, Jung SR, Kim KW, Yeon JH, Park CG, Nam JH, Hille B, Suh BC. Allosteric modulation of alternatively spliced Ca 2+-activated Cl - channels TMEM16A by PI(4,5)P 2 and CaMKII. Proc Natl Acad Sci U S A 2020; 117:30787-30798. [PMID: 33199590 PMCID: PMC7720229 DOI: 10.1073/pnas.2014520117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transmembrane 16A (TMEM16A, anoctamin1), 1 of 10 TMEM16 family proteins, is a Cl- channel activated by intracellular Ca2+ and membrane voltage. This channel is also regulated by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. We find that two splice variants of TMEM16A show different sensitivity to endogenous PI(4,5)P2 degradation, where TMEM16A(ac) displays higher channel activity and more current inhibition by PI(4,5)P2 depletion than TMEM16A(a). These two channel isoforms differ in the alternative splicing of the c-segment (exon 13). The current amplitude and PI(4,5)P2 sensitivity of both TMEM16A(ac) and (a) are significantly strengthened by decreased free cytosolic ATP and by conditions that decrease phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaMKII). Noise analysis suggests that the augmentation of currents is due to a rise of single-channel current (i), but not of channel number (N) or open probability (PO). Mutagenesis points to arginine 486 in the first intracellular loop as a putative binding site for PI(4,5)P2, and to serine 673 in the third intracellular loop as a site for regulatory channel phosphorylation that modulates the action of PI(4,5)P2 In silico simulation suggests how phosphorylation of S673 allosterically and differently changes the structure of the distant PI(4,5)P2-binding site between channel splice variants with and without the c-segment exon. In sum, our study reveals the following: differential regulation of alternatively spliced TMEM16A(ac) and (a) by plasma membrane PI(4,5)P2, modification of these effects by channel phosphorylation, identification of the molecular sites, and mechanistic explanation by in silico simulation.
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Affiliation(s)
- Woori Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Kwon-Woo Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Jun-Hee Yeon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Cheon-Gyu Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, College of Medicine, Dongguk University, Gyeongju 38066, Republic of Korea
- Ion Channel Disease Research Center, College of Medicine, Dongguk University, Goyang, Gyeonggi-do 10326, Republic of Korea
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea;
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12
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Kramvis I, van Westen R, Lammertse HCA, Riga D, Heistek TS, Loebel A, Spijker S, Mansvelder HD, Meredith RM. Dysregulated Prefrontal Cortex Inhibition in Prepubescent and Adolescent Fragile X Mouse Model. Front Mol Neurosci 2020; 13:88. [PMID: 32528248 PMCID: PMC7264168 DOI: 10.3389/fnmol.2020.00088] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/28/2020] [Indexed: 11/13/2022] Open
Abstract
Changes in excitation and inhibition are associated with the pathobiology of neurodevelopmental disorders of intellectual disability and autism and are widely described in Fragile X syndrome (FXS). In the prefrontal cortex (PFC), essential for cognitive processing, excitatory connectivity and plasticity are found altered in the FXS mouse model, however, little is known about the state of inhibition. To that end, we investigated GABAergic signaling in the Fragile X Mental Retardation 1 (FMR1) knock out (Fmr1-KO) mouse medial PFC (mPFC). We report changes at the molecular, and functional levels of inhibition at three (prepubescence) and six (adolescence) postnatal weeks. Functional changes were most prominent during early postnatal development, resulting in stronger inhibition, through increased synaptic inhibitory drive and amplitude, and reduction of inhibitory short-term synaptic depression. Noise analysis of prepubescent post-synaptic currents demonstrated an increased number of receptors opening during peak current in Fmr1-KO inhibitory synapses. During adolescence amplitudes and plasticity changes normalized, however, the inhibitory drive was now reduced in Fmr1-KO, while synaptic kinetics were prolonged. Finally, adolescent GABAA receptor subunit α2 and GABAB receptor subtype B1 expression levels were different in Fmr1-KOs than WT littermate controls. Together these results extend the degree of synaptic GABAergic alterations in FXS, now to the mPFC of Fmr1-KO mice, a behaviourally relevant brain region in neurodevelopmental disorder pathology.
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Affiliation(s)
- Ioannis Kramvis
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Rhodé van Westen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Hanna C A Lammertse
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Danai Riga
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Tim S Heistek
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Alex Loebel
- Department of Neurobiology, Ludwig-Maximilians Universitat, Munich, Germany
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
| | - Rhiannon M Meredith
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, Netherlands
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13
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Chen TJ, Kula B, Nagy B, Barzan R, Gall A, Ehrlich I, Kukley M. In Vivo Regulation of Oligodendrocyte Precursor Cell Proliferation and Differentiation by the AMPA-Receptor Subunit GluA2. Cell Rep 2019; 25:852-861.e7. [PMID: 30355492 DOI: 10.1016/j.celrep.2018.09.066] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 08/09/2018] [Accepted: 09/19/2018] [Indexed: 01/01/2023] Open
Abstract
The functional role of AMPA receptor (AMPAR)-mediated synaptic signaling between neurons and oligodendrocyte precursor cells (OPCs) remains enigmatic. We modified the properties of AMPARs at axon-OPC synapses in the mouse corpus callosum in vivo during the peak of myelination by targeting the GluA2 subunit. Expression of the unedited (Ca2+ permeable) or the pore-dead GluA2 subunit of AMPARs triggered proliferation of OPCs and reduced their differentiation into oligodendrocytes. Expression of the cytoplasmic C-terminal (GluA2(813-862)) of the GluA2 subunit (C-tail), a modification designed to affect the interaction between GluA2 and AMPAR-binding proteins and to perturb trafficking of GluA2-containing AMPARs, decreased the differentiation of OPCs without affecting their proliferation. These findings suggest that ionotropic and non-ionotropic properties of AMPARs in OPCs, as well as specific aspects of AMPAR-mediated signaling at axon-OPC synapses in the mouse corpus callosum, are important for balancing the response of OPCs to proliferation and differentiation cues.
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Affiliation(s)
- Ting-Jiun Chen
- Group of Neuron Glia Interaction, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Graduate Training Centre of Neuroscience, University of Tübingen, 72074 Tübingen, Germany
| | - Bartosz Kula
- Group of Neuron Glia Interaction, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Graduate Training Centre of Neuroscience, University of Tübingen, 72074 Tübingen, Germany
| | - Bálint Nagy
- Group of Neuron Glia Interaction, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Graduate Training Centre of Neuroscience, University of Tübingen, 72074 Tübingen, Germany; Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria
| | - Ruxandra Barzan
- Group of Neuron Glia Interaction, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Graduate Training Centre of Neuroscience, University of Tübingen, 72074 Tübingen, Germany
| | - Andrea Gall
- Learning and Memory Group, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Learning and Memory Group, Hertie Institute for Brain Research, University of Tübingen, 72076 Tübingen, Germany; Department of Neurobiology, IBBS, University of Stuttgart, 70569 Stuttgart, Germany
| | - Ingrid Ehrlich
- Learning and Memory Group, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Learning and Memory Group, Hertie Institute for Brain Research, University of Tübingen, 72076 Tübingen, Germany; Department of Neurobiology, IBBS, University of Stuttgart, 70569 Stuttgart, Germany
| | - Maria Kukley
- Group of Neuron Glia Interaction, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, 72076 Tübingen, Germany; Department of Ophthalmology, Research Institute of Ophthalmology, Faculty of Medicine, University Hospital Tübingen, 72076 Tübingen, Germany.
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14
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Smith-Dijak AI, Nassrallah WB, Zhang LYJ, Geva M, Hayden MR, Raymond LA. Impairment and Restoration of Homeostatic Plasticity in Cultured Cortical Neurons From a Mouse Model of Huntington Disease. Front Cell Neurosci 2019; 13:209. [PMID: 31156395 PMCID: PMC6532531 DOI: 10.3389/fncel.2019.00209] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Huntington disease (HD) is an inherited neurodegenerative disorder caused by a mutation in the huntingtin gene. The onset of symptoms is preceded by synaptic dysfunction. Homeostatic synaptic plasticity (HSP) refers to processes that maintain the stability of networks of neurons, thought to be required to enable new learning and cognitive flexibility. One type of HSP is synaptic scaling, in which the strength of all of the synapses onto a cell increases or decreases following changes in the cell’s level of activity. Several pathways implicated in synaptic scaling are dysregulated in HD, including brain-derived neurotrophic factor (BDNF) and calcium signaling. Here, we investigated whether HSP is disrupted in cortical neurons from an HD mouse model. We treated cultured cortical neurons from wild-type (WT) FVB/N or YAC128 HD mice with tetrodotoxin (TTX) for 48 h to silence action potentials and then recorded miniature excitatory postsynaptic currents. In WT cultures, these increased in both amplitude and frequency after TTX treatment, and further experiments showed that this was a result of insertion of AMPA receptors and formation of new synapses, respectively. Manipulation of BDNF concentration in the culture medium revealed that BDNF signaling contributed to these changes. In contrast to WT cortical neurons, YAC128 cultures showed no response to action potential silencing. Strikingly, we were able to restore the TTX-induced changes in YAC128 cultures by treating them with pridopidine, a drug which enhances BDNF signaling through stimulation of the sigma-1 receptor (S1R), and with the S1R agonist 3-PPP. These data provide evidence for disruption of HSP in cortical neurons from an HD mouse model that is restored by stimulation of S1R. Our results suggest a potential new direction for developing therapy to mitigate cognitive deficits in HD.
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Affiliation(s)
- Amy I Smith-Dijak
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, BC, Canada.,Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Wissam B Nassrallah
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, BC, Canada.,Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Lily Y J Zhang
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Michal Geva
- Research and Development, Teva Pharmaceutical Industries Ltd., Netanya, Israel
| | - Michael R Hayden
- Research and Development, Teva Pharmaceutical Industries Ltd., Netanya, Israel.,Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, BC, Canada
| | - Lynn A Raymond
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
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15
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Comhair J, Devoght J, Morelli G, Harvey RJ, Briz V, Borrie SC, Bagni C, Rigo JM, Schiffmann SN, Gall D, Brône B, Molchanova SM. Alpha2-Containing Glycine Receptors Promote Neonatal Spontaneous Activity of Striatal Medium Spiny Neurons and Support Maturation of Glutamatergic Inputs. Front Mol Neurosci 2018; 11:380. [PMID: 30374290 PMCID: PMC6196267 DOI: 10.3389/fnmol.2018.00380] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 09/24/2018] [Indexed: 12/16/2022] Open
Abstract
Glycine receptors (GlyRs) containing the α2 subunit are highly expressed in the developing brain, where they regulate neuronal migration and maturation, promote spontaneous network activity and subsequent development of synaptic connections. Mutations in GLRA2 are associated with autism spectrum disorder, but the underlying pathophysiology is not described yet. Here, using Glra2-knockout mice, we found a GlyR-dependent effect on neonatal spontaneous activity of dorsal striatum medium spiny neurons (MSNs) and maturation of the incoming glutamatergic innervation. Our data demonstrate that functional GlyRs are highly expressed in MSNs of one-week-old mice, but they do not generate endogenous chloride-mediated tonic or phasic current. Despite of that, knocking out the Glra2 severely affects the shape of action potentials and impairs spontaneous activity and the frequency of miniature AMPA receptor-mediated currents in MSNs. This reduction in spontaneous activity and glutamatergic signaling can attribute to the observed changes in neonatal behavioral phenotypes as seen in ultrasonic vocalizations and righting reflex. In adult Glra2-knockout animals, the glutamatergic synapses in MSNs remain functionally underdeveloped. The number of glutamatergic synapses and release probability at presynaptic site remain unaffected, but the amount of postsynaptic AMPA receptors is decreased. This deficit is a consequence of impaired development of the neuronal circuitry since acute inhibition of GlyRs by strychnine in adult MSNs does not affect the properties of glutamatergic synapses. Altogether, these results demonstrate that GlyR-mediated signaling supports neonatal spontaneous MSN activity and, in consequence, promotes the functional maturation of glutamatergic synapses on MSNs. The described mechanism might shed light on the pathophysiological mechanisms in GLRA2-linked autism spectrum disorder cases.
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Affiliation(s)
- Joris Comhair
- Laboratory of Neurophysiology, ULB-Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium.,BIOMED Research Institute, University of Hasselt, Hasselt, Belgium
| | - Jens Devoght
- BIOMED Research Institute, University of Hasselt, Hasselt, Belgium
| | - Giovanni Morelli
- BIOMED Research Institute, University of Hasselt, Hasselt, Belgium
| | - Robert J Harvey
- School of Health and Sport Sciences, University of the Sunshine Coast, Sippy Downs, QLD, Australia.,Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Victor Briz
- Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease, KU Leuven, Leuven, Belgium.,VIB Center for the Biology of Disease, Leuven, Belgium
| | - Sarah C Borrie
- Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease, KU Leuven, Leuven, Belgium.,VIB Center for the Biology of Disease, Leuven, Belgium
| | - Claudia Bagni
- Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease, KU Leuven, Leuven, Belgium.,VIB Center for the Biology of Disease, Leuven, Belgium
| | - Jean-Michel Rigo
- BIOMED Research Institute, University of Hasselt, Hasselt, Belgium
| | - Serge N Schiffmann
- Laboratory of Neurophysiology, ULB-Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - David Gall
- Laboratory of Neurophysiology, ULB-Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Bert Brône
- BIOMED Research Institute, University of Hasselt, Hasselt, Belgium
| | - Svetlana M Molchanova
- Laboratory of Neurophysiology, ULB-Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
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16
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Cordella A, Krashia P, Nobili A, Pignataro A, La Barbera L, Viscomi MT, Valzania A, Keller F, Ammassari-Teule M, Mercuri NB, Berretta N, D'Amelio M. Dopamine loss alters the hippocampus-nucleus accumbens synaptic transmission in the Tg2576 mouse model of Alzheimer's disease. Neurobiol Dis 2018; 116:142-154. [DOI: 10.1016/j.nbd.2018.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/07/2018] [Accepted: 05/15/2018] [Indexed: 12/14/2022] Open
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17
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Hay YA, Naudé J, Faure P, Lambolez B. Target Interneuron Preference in Thalamocortical Pathways Determines the Temporal Structure of Cortical Responses. Cereb Cortex 2018; 29:2815-2831. [DOI: 10.1093/cercor/bhy148] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 05/03/2018] [Accepted: 06/04/2018] [Indexed: 11/14/2022] Open
Abstract
Abstract
Sensory processing relies on fast detection of changes in environment, as well as integration of contextual cues over time. The mechanisms by which local circuits of the cerebral cortex simultaneously perform these opposite processes remain obscure. Thalamic “specific” nuclei relay sensory information, whereas “nonspecific” nuclei convey information on the environmental and behavioral contexts. We expressed channelrhodopsin in the ventrobasal specific (sensory) or the rhomboid nonspecific (contextual) thalamic nuclei. By selectively activating each thalamic pathway, we found that nonspecific inputs powerfully activate adapting (slow-responding) interneurons but weakly connect fast-spiking interneurons, whereas specific inputs exhibit opposite interneuron preference. Specific inputs thereby induce rapid feedforward inhibition that limits response duration, whereas, in the same cortical area, nonspecific inputs elicit delayed feedforward inhibition that enables lasting recurrent excitation. Using a mean field model, we confirm that cortical response dynamics depends on the type of interneuron targeted by thalamocortical inputs and show that efficient recruitment of adapting interneurons prolongs the cortical response and allows the summation of sensory and contextual inputs. Hence, target choice between slow- and fast-responding inhibitory neurons endows cortical networks with a simple computational solution to perform both sensory detection and integration.
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Affiliation(s)
- Y Audrey Hay
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| | - Jérémie Naudé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| | - Philippe Faure
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
| | - Bertrand Lambolez
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine-Institut de Biologie Paris Seine (NPS-IBPS), Paris, France
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18
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Rothman JS, Silver RA. NeuroMatic: An Integrated Open-Source Software Toolkit for Acquisition, Analysis and Simulation of Electrophysiological Data. Front Neuroinform 2018; 12:14. [PMID: 29670519 PMCID: PMC5893720 DOI: 10.3389/fninf.2018.00014] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/15/2018] [Indexed: 12/21/2022] Open
Abstract
Acquisition, analysis and simulation of electrophysiological properties of the nervous system require multiple software packages. This makes it difficult to conserve experimental metadata and track the analysis performed. It also complicates certain experimental approaches such as online analysis. To address this, we developed NeuroMatic, an open-source software toolkit that performs data acquisition (episodic, continuous and triggered recordings), data analysis (spike rasters, spontaneous event detection, curve fitting, stationarity) and simulations (stochastic synaptic transmission, synaptic short-term plasticity, integrate-and-fire and Hodgkin-Huxley-like single-compartment models). The merging of a wide range of tools into a single package facilitates a more integrated style of research, from the development of online analysis functions during data acquisition, to the simulation of synaptic conductance trains during dynamic-clamp experiments. Moreover, NeuroMatic has the advantage of working within Igor Pro, a platform-independent environment that includes an extensive library of built-in functions, a history window for reviewing the user's workflow and the ability to produce publication-quality graphics. Since its original release, NeuroMatic has been used in a wide range of scientific studies and its user base has grown considerably. NeuroMatic version 3.0 can be found at http://www.neuromatic.thinkrandom.com and https://github.com/SilverLabUCL/NeuroMatic.
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Affiliation(s)
- Jason S Rothman
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - R Angus Silver
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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19
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Studniarczyk D, Needham EL, Mitchison HM, Farrant M, Cull-Candy SG. Altered Cerebellar Short-Term Plasticity but No Change in Postsynaptic AMPA-Type Glutamate Receptors in a Mouse Model of Juvenile Batten Disease. eNeuro 2018; 5:ENEURO.0387-17.2018. [PMID: 29780879 PMCID: PMC5956745 DOI: 10.1523/eneuro.0387-17.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/22/2018] [Accepted: 03/27/2018] [Indexed: 12/28/2022] Open
Abstract
Juvenile Batten disease is the most common progressive neurodegenerative disorder of childhood. It is associated with mutations in the CLN3 gene, causing loss of function of CLN3 protein and degeneration of cerebellar and retinal neurons. It has been proposed that changes in granule cell AMPA-type glutamate receptors (AMPARs) contribute to the cerebellar dysfunction. In this study, we compared AMPAR properties and synaptic transmission in cerebellar granule cells from wild-type and Cln3 knock-out mice. In Cln3Δex1-6 cells, the amplitude of AMPA-evoked whole-cell currents was unchanged. Similarly, we found no change in the amplitude, kinetics, or rectification of synaptic currents evoked by individual quanta, or in their underlying single-channel conductance. We found no change in cerebellar expression of GluA2 or GluA4 protein. By contrast, we observed a reduced number of quantal events following mossy-fiber stimulation in Sr2+, altered short-term plasticity in conditions of reduced extracellular Ca2+, and reduced mossy fiber vesicle number. Thus, while our results suggest early presynaptic changes in the Cln3Δex1-6 mouse model of juvenile Batten disease, they reveal no evidence for altered postsynaptic AMPARs.
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Affiliation(s)
- Dorota Studniarczyk
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Elizabeth L. Needham
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Hannah M. Mitchison
- UCL Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, United Kingdom
| | - Mark Farrant
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Stuart G. Cull-Candy
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
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20
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Nobili A, Krashia P, Cordella A, La Barbera L, Dell'Acqua MC, Caruso A, Pignataro A, Marino R, Sciarra F, Biamonte F, Scattoni ML, Ammassari-Teule M, Cecconi F, Berretta N, Keller F, Mercuri NB, D'Amelio M. Ambra1 Shapes Hippocampal Inhibition/Excitation Balance: Role in Neurodevelopmental Disorders. Mol Neurobiol 2018; 55:7921-7940. [PMID: 29488136 PMCID: PMC6132777 DOI: 10.1007/s12035-018-0911-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/15/2018] [Indexed: 01/04/2023]
Abstract
Imbalances between excitatory and inhibitory synaptic transmission cause brain network dysfunction and are central to the pathogenesis of neurodevelopmental disorders. Parvalbumin interneurons are highly implicated in this imbalance. Here, we probed the social behavior and hippocampal function of mice carrying a haploinsufficiency for Ambra1, a pro-autophagic gene crucial for brain development. We show that heterozygous Ambra1 mice (Ambra+/−) are characterized by loss of hippocampal parvalbumin interneurons, decreases in the inhibition/excitation ratio, and altered social behaviors that are solely restricted to the female gender. Loss of parvalbumin interneurons in Ambra1+/− females is further linked to reductions of the inhibitory drive onto principal neurons and alterations in network oscillatory activity, CA1 synaptic plasticity, and pyramidal neuron spine density. Parvalbumin interneuron loss is underlined by increased apoptosis during the embryonic development of progenitor neurons in the medial ganglionic eminence. Together, these findings identify an Ambra1-dependent mechanism that drives inhibition/excitation imbalance in the hippocampus, contributing to abnormal brain activity reminiscent of neurodevelopmental disorders.
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Affiliation(s)
- Annalisa Nobili
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy
| | - Paraskevi Krashia
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy. .,Department of Systems Medicine, University of Rome 'Tor Vergata', 00133, Rome, Italy.
| | - Alberto Cordella
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Department of Systems Medicine, University of Rome 'Tor Vergata', 00133, Rome, Italy
| | - Livia La Barbera
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Department of Systems Medicine, University of Rome 'Tor Vergata', 00133, Rome, Italy
| | - Maria Concetta Dell'Acqua
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy
| | - Angela Caruso
- Research Coordination and Support Service, Istituto Superiore di Sanità (ISS), 00161, Rome, Italy
| | - Annabella Pignataro
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Institute of Cell Biology and Neurobiology (IBCN), National Research Council (CNR), 00143, Rome, Italy
| | - Ramona Marino
- Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy
| | - Francesca Sciarra
- Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy
| | - Filippo Biamonte
- Institute of Histology and Embryology, "A. Gemelli" Faculty of Medicine, Catholic University of the Sacred Heart, 00168, Rome, Italy
| | - Maria Luisa Scattoni
- Research Coordination and Support Service, Istituto Superiore di Sanità (ISS), 00161, Rome, Italy
| | - Martine Ammassari-Teule
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Institute of Cell Biology and Neurobiology (IBCN), National Research Council (CNR), 00143, Rome, Italy
| | - Francesco Cecconi
- Department of Biology, University of Rome 'Tor Vergata', 00133, Rome, Italy.,Cell Stress and Survival Group, Danish Cancer Society Research Center, DK-2100, Copenhagen, Denmark.,Department of Pediatric Hematology and Oncology, IRCSS Bambino Gesu Children's Hospital, 00165, Rome, Italy
| | - Nicola Berretta
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy
| | - Flavio Keller
- Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy
| | - Nicola Biagio Mercuri
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy.,Department of Systems Medicine, University of Rome 'Tor Vergata', 00133, Rome, Italy
| | - Marcello D'Amelio
- Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, 00143, Rome, Italy. .,Department of Medicine, University Campus-Biomedico, 00128, Rome, Italy.
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21
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Glutamate Activates AMPA Receptor Conductance in the Developing Schwann Cells of the Mammalian Peripheral Nerves. J Neurosci 2017; 37:11818-11834. [PMID: 29089441 DOI: 10.1523/jneurosci.1168-17.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 09/01/2017] [Accepted: 10/02/2017] [Indexed: 11/21/2022] Open
Abstract
Schwann cells (SCs) are myelinating cells of the PNS. Although SCs are known to express different channels and receptors on their surface, little is known about the activation and function of these proteins. Ionotropic glutamate receptors are thought to play an essential role during development of SC lineage and during peripheral nerve injury, so we sought to study their functional properties. We established a novel preparation of living peripheral nerve slices with preserved cellular architecture and used a patch-clamp technique to study AMPA-receptor (AMPAR)-mediated currents in SCs for the first time. We found that the majority of SCs in the nerves dissected from embryonic and neonatal mice of both sexes respond to the application of glutamate with inward current mediated by Ca2+-permeable AMPARs. Using stationary fluctuation analysis (SFA), we demonstrate that single-channel conductance of AMPARs in SCs is 8-11 pS, which is comparable to that in neurons. We further show that, when SCs become myelinating, they downregulate functional AMPARs. This study is the first to demonstrate AMPAR-mediated conductance in SCs of vertebrates, to investigate elementary properties of AMPARs in these cells, and to provide detailed electrophysiological and morphological characterization of SCs at different stages of development.SIGNIFICANCE STATEMENT We provide several important conceptual and technical advances in research on the PNS. We pioneer the first description of AMPA receptor (AMPAR)-mediated currents in the PNS glia of vertebrates and provide new insights into the properties of AMPAR channels in peripheral glia; for example, their Ca2+ permeability and single-channel conductance. We describe for the first time the electrophysiological and morphological properties of Schwann cells (SCs) at different stages of development and show that functional AMPARs are expressed only in developing, not mature, SCs. Finally, we introduce a preparation of peripheral nerve slices for patch-clamp recordings. This preparation opens new possibilities for studying the physiology of SCs in animal models and in surgical human samples.
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22
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Hartveit E, Zandt BJ, Madsen E, Castilho Á, Mørkve SH, Veruki ML. AMPA receptors at ribbon synapses in the mammalian retina: kinetic models and molecular identity. Brain Struct Funct 2017; 223:769-804. [PMID: 28936725 DOI: 10.1007/s00429-017-1520-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 09/10/2017] [Indexed: 10/24/2022]
Abstract
In chemical synapses, neurotransmitter molecules released from presynaptic vesicles activate populations of postsynaptic receptors that vary in functional properties depending on their subunit composition. Differential expression and localization of specific receptor subunits are thought to play fundamental roles in signal processing, but our understanding of how that expression is adapted to the signal processing in individual synapses and microcircuits is limited. At ribbon synapses, glutamate release is independent of action potentials and characterized by a high and rapidly changing rate of release. Adequately translating such presynaptic signals into postsynaptic electrical signals poses a considerable challenge for the receptor channels in these synapses. Here, we investigated the functional properties of AMPA receptors of AII amacrine cells in rat retina that receive input at spatially segregated ribbon synapses from OFF-cone and rod bipolar cells. Using patch-clamp recording from outside-out patches, we measured the concentration dependence of response amplitude and steady-state desensitization, the single-channel conductance and the maximum open probability. The GluA4 subunit seems critical for the functional properties of AMPA receptors in AII amacrines and immunocytochemical labeling suggested that GluA4 is located at synapses made by both OFF-cone bipolar cells and rod bipolar cells. Finally, we used a series of experimental observables to develop kinetic models for AII amacrine AMPA receptors and subsequently used the models to explore the behavior of the receptors and responses generated by glutamate concentration profiles mimicking those occurring in synapses. These models will facilitate future in silico modeling of synaptic signaling and processing in AII amacrine cells.
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Affiliation(s)
- Espen Hartveit
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
| | - Bas-Jan Zandt
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Blue Brain Project, École polytechnique fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Eirik Madsen
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Department of Radiology, Førde Central Hospital, Førde, Norway
| | - Áurea Castilho
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway
| | - Svein Harald Mørkve
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.,Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.,Department of Radiology, Haukeland University Hospital, Bergen, Norway
| | - Margaret Lin Veruki
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
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23
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Striatopallidal Neuron NMDA Receptors Control Synaptic Connectivity, Locomotor, and Goal-Directed Behaviors. J Neurosci 2017; 36:4976-92. [PMID: 27147651 DOI: 10.1523/jneurosci.2717-15.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 03/07/2016] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED The basal ganglia (BG) control action selection, motor programs, habits, and goal-directed learning. The striatum, the principal input structure of BG, is predominantly composed of medium-sized spiny neurons (MSNs). Arising from these spatially intermixed MSNs, two inhibitory outputs form two main efferent pathways, the direct and indirect pathways. Striatonigral MSNs give rise to the activating, direct pathway MSNs and striatopallidal MSNs to the inhibitory, indirect pathway (iMSNs). BG output nuclei integrate information from both pathways to fine-tune motor procedures and to acquire complex habits and skills. Therefore, balanced activity between both pathways is crucial for harmonious functions of the BG. Despite the increase in knowledge concerning the role of glutamate NMDA receptors (NMDA-Rs) in the striatum, understanding of the specific functions of NMDA-R iMSNs is still lacking. For this purpose, we generated a conditional knock-out mouse to address the functions of the NMDA-R in the indirect pathway. At the cellular level, deletion of GluN1 in iMSNs leads to a reduction in the number and strength of the excitatory corticostriatopallidal synapses. The subsequent scaling down in input integration leads to dysfunctional changes in BG output, which is seen as reduced habituation, delay in goal-directed learning, lack of associative behavior, and impairment in action selection or skill learning. The NMDA-R deletion in iMSNs causes a decrease in the synaptic strength of striatopallidal neurons, which in turn might lead to a imbalanced integration between direct and indirect MSN pathways, making mice less sensitive to environmental change. Therefore, their ability to learn and adapt to the environment-based experience was significantly affected. SIGNIFICANCE STATEMENT The striatum controls habits, locomotion, and goal-directed behaviors by coordinated activation of two antagonistic pathways. Insofar as NMDA receptors (NMDA-Rs) play a key role in synaptic plasticity essential for sustaining these behaviors, we generated a mouse model lacking NMDA-Rs specifically in striatopallidal neurons. To our knowledge, this is the first time that a specific deletion of inhibitory, indirect pathway medium-sized spiny neuron (iMSN) NMDA-Rs has been used to address the role of these receptors in the inhibitory pathway. Importantly, we found that this specific deletion led to a significant reduction in the number and strength of the cortico-iMSN synapses, which resulted in the significant impairments of behaviors orchestrated by the basal ganglia. Our findings indicate that the NMDA-Rs of the indirect pathway are essential for habituation, action selection, and goal-directed learning.
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24
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Renner MC, Albers EH, Gutierrez-Castellanos N, Reinders NR, van Huijstee AN, Xiong H, Lodder TR, Kessels HW. Synaptic plasticity through activation of GluA3-containing AMPA-receptors. eLife 2017; 6:25462. [PMID: 28762944 PMCID: PMC5578739 DOI: 10.7554/elife.25462] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 07/31/2017] [Indexed: 11/13/2022] Open
Abstract
Excitatory synaptic transmission is mediated by AMPA-type glutamate receptors (AMPARs). In CA1 pyramidal neurons of the hippocampus two types of AMPARs predominate: those that contain subunits GluA1 and GluA2 (GluA1/2), and those that contain GluA2 and GluA3 (GluA2/3). Whereas subunits GluA1 and GluA2 have been extensively studied, the contribution of GluA3 to synapse physiology has remained unclear. Here we show in mice that GluA2/3s are in a low-conductance state under basal conditions, and although present at synapses they contribute little to synaptic currents. When intracellular cyclic AMP (cAMP) levels rise, GluA2/3 channels shift to a high-conductance state, leading to synaptic potentiation. This cAMP-driven synaptic potentiation requires the activation of both protein kinase A (PKA) and the GTPase Ras, and is induced upon the activation of β-adrenergic receptors. Together, these experiments reveal a novel type of plasticity at CA1 hippocampal synapses that is expressed by the activation of GluA3-containing AMPARs.
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Affiliation(s)
- Maria C Renner
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Eva Hh Albers
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Nicolas Gutierrez-Castellanos
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Niels R Reinders
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Aile N van Huijstee
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Hui Xiong
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Tessa R Lodder
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Helmut W Kessels
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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25
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Gutierrez-Castellanos N, Da Silva-Matos CM, Zhou K, Canto CB, Renner MC, Koene LMC, Ozyildirim O, Sprengel R, Kessels HW, De Zeeuw CI. Motor Learning Requires Purkinje Cell Synaptic Potentiation through Activation of AMPA-Receptor Subunit GluA3. Neuron 2017; 93:409-424. [PMID: 28103481 PMCID: PMC5263704 DOI: 10.1016/j.neuron.2016.11.046] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 09/28/2016] [Accepted: 11/17/2016] [Indexed: 12/21/2022]
Abstract
Accumulating evidence indicates that cerebellar long-term potentiation (LTP) is necessary for procedural learning. However, little is known about its underlying molecular mechanisms. Whereas AMPA receptor (AMPAR) subunit rules for synaptic plasticity have been extensively studied in relation to declarative learning, it is unclear whether these rules apply to cerebellum-dependent motor learning. Here we show that LTP at the parallel-fiber-to-Purkinje-cell synapse and adaptation of the vestibulo-ocular reflex depend not on GluA1- but on GluA3-containing AMPARs. In contrast to the classic form of LTP implicated in declarative memory formation, this form of LTP does not require GluA1-AMPAR trafficking but rather requires changes in open-channel probability of GluA3-AMPARs mediated by cAMP signaling and activation of the protein directly activated by cAMP (Epac). We conclude that vestibulo-cerebellar motor learning is the first form of memory acquisition shown to depend on GluA3-dependent synaptic potentiation by increasing single-channel conductance. Cerebellar learning depends on expression of GluA3, but not GluA1, in Purkinje cells GluA3 is required to induce LTP, but not LTD, at PF-PC synapses GluA3-dependent potentiation involves a cAMP-driven change in channel conductance GluA3-mediated LTP and learning are induced via cAMP-mediated Epac activation
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Affiliation(s)
- Nicolas Gutierrez-Castellanos
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Cerebellar Coordination and Cognition Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Neuroscience, Erasmus MC Rotterdam, 3015 GE Rotterdam, the Netherlands
| | - Carla M Da Silva-Matos
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Cerebellar Coordination and Cognition Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands
| | - Kuikui Zhou
- Department of Neuroscience, Erasmus MC Rotterdam, 3015 GE Rotterdam, the Netherlands
| | - Cathrin B Canto
- Cerebellar Coordination and Cognition Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands
| | - Maria C Renner
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands
| | - Linda M C Koene
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands
| | - Ozgecan Ozyildirim
- Cerebellar Coordination and Cognition Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands
| | - Rolf Sprengel
- Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Helmut W Kessels
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands.
| | - Chris I De Zeeuw
- Cerebellar Coordination and Cognition Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Neuroscience, Erasmus MC Rotterdam, 3015 GE Rotterdam, the Netherlands
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26
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Watson JF, Ho H, Greger IH. Synaptic transmission and plasticity require AMPA receptor anchoring via its N-terminal domain. eLife 2017; 6. [PMID: 28290985 PMCID: PMC5370185 DOI: 10.7554/elife.23024] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 03/04/2017] [Indexed: 12/02/2022] Open
Abstract
AMPA-type glutamate receptors (AMPARs) mediate fast excitatory neurotransmission and are selectively recruited during activity-dependent plasticity to increase synaptic strength. A prerequisite for faithful signal transmission is the positioning and clustering of AMPARs at postsynaptic sites. The mechanisms underlying this positioning have largely been ascribed to the receptor cytoplasmic C-termini and to AMPAR-associated auxiliary subunits, both interacting with the postsynaptic scaffold. Here, using mouse organotypic hippocampal slices, we show that the extracellular AMPAR N-terminal domain (NTD), which projects midway into the synaptic cleft, plays a fundamental role in this process. This highly sequence-diverse domain mediates synaptic anchoring in a subunit-selective manner. Receptors lacking the NTD exhibit increased mobility in synapses, depress synaptic transmission and are unable to sustain long-term potentiation (LTP). Thus, synaptic transmission and the expression of LTP are dependent upon an AMPAR anchoring mechanism that is driven by the NTD. DOI:http://dx.doi.org/10.7554/eLife.23024.001 Neurons send signals via electrical impulses that are transmitted between cells by small molecules known as neurotransmitters. The information is passed from neuron to neuron at specialized points of contact termed synapses. On release of neurotransmitters from the first neuron, the molecules attach to ‘docking stations’ called receptors on the next neuron, referred to as the postsynaptic cell. One of these receptors, the AMPA receptor, transmits signals by binding to a neurotransmitter called glutamate. Previous research has shown that in order to bind glutamate effectively, these receptors need to be trapped and anchored at the correct location at the synapse. This trapping mechanism controls the number of receptors present, which strengthens the synapse, and ultimately mediates learning and memory. However, it is still not clear how AMPA receptor trapping is achieved. To investigate this question, Watson et al. examined how AMPA receptors (and mutant forms of the receptor) affect the communication between neurons using brain slices from mice. The experiments show that an external segment of the AMPA receptor called the N-terminal domain (or NTD for short) is a key element for receptor anchoring at the postsynapse. The AMPA receptor is made out of four different subunits; when the NTD portion was removed from one specific subunit, fewer receptors were anchored correctly at the postsynapse. When the NTD was removed from another subunit, it completely prevented the synapse from learning. Therefore, the NTD brings about subunit-selective anchoring of the AMPA receptor, which affects the ability of the synapse to transmit signals. Important next steps would be to identify the proteins that interact with the NTD and how this specific anchoring affects the strength of the synapse. Another key step will be to understand what mechanisms control the number of AMPA receptors at synapses, to ultimately enable learning. DOI:http://dx.doi.org/10.7554/eLife.23024.002
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Affiliation(s)
- Jake F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Hinze Ho
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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27
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Zhou Y, Tencerová B, Hartveit E, Veruki ML. Functional NMDA receptors are expressed by both AII and A17 amacrine cells in the rod pathway of the mammalian retina. J Neurophysiol 2016; 115:389-403. [PMID: 26561610 PMCID: PMC4760463 DOI: 10.1152/jn.00947.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/08/2015] [Indexed: 11/22/2022] Open
Abstract
At many glutamatergic synapses, non-N-methyl-d-aspartate (NMDA) and NMDA receptors are coexpressed postsynaptically. In the mammalian retina, glutamatergic rod bipolar cells are presynaptic to two rod amacrine cells (AII and A17) that constitute dyad postsynaptic partners opposite each presynaptic active zone. Whereas there is strong evidence for expression of non-NMDA receptors by both AII and A17 amacrines, the expression of NMDA receptors by the pre- and postsynaptic neurons in this microcircuit has not been resolved. In this study, using patch-clamp recording from visually identified cells in rat retinal slices, we investigated the expression and functional properties of NMDA receptors in these cells with a combination of pharmacological and biophysical methods. Pressure application of NMDA did not evoke a response in rod bipolar cells, but for both AII and A17 amacrines, NMDA evoked responses that were blocked by a competitive antagonist (CPP) applied extracellularly and an open channel blocker (MK-801) applied intracellularly. NMDA-evoked responses also displayed strong Mg(2+)-dependent voltage block and were independent of gap junction coupling. With low-frequency application (60-s intervals), NMDA-evoked responses remained stable for up to 50 min, but with higher-frequency stimulation (10- to 20-s intervals), NMDA responses were strongly and reversibly suppressed. We observed strong potentiation when NMDA was applied in nominally Ca(2+)-free extracellular solution, potentially reflecting Ca(2+)-dependent NMDA receptor inactivation. These results indicate that expression of functional (i.e., conductance-increasing) NMDA receptors is common to both AII and A17 amacrine cells and suggest that these receptors could play an important role for synaptic signaling, integration, or plasticity in the rod pathway.
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Affiliation(s)
- Yifan Zhou
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
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28
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Time-dependent modulation of glutamate synapses onto 5-HT neurons by antidepressant treatment. Neuropharmacology 2015; 95:130-43. [DOI: 10.1016/j.neuropharm.2015.02.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/18/2015] [Accepted: 02/19/2015] [Indexed: 11/23/2022]
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29
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Feigenspan A, Babai N. Functional properties of spontaneous excitatory currents and encoding of light/dark transitions in horizontal cells of the mouse retina. Eur J Neurosci 2015; 42:2615-32. [PMID: 26173960 DOI: 10.1111/ejn.13016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 06/23/2015] [Accepted: 07/07/2015] [Indexed: 02/01/2023]
Abstract
As all visual information is represented in the spatio-temporal dynamics of transmitter release from photoreceptors and the combined postsynaptic responses of second-order neurons, appropriate synaptic transfer functions are fundamental for a meaningful perception of the visual world. The functional contribution of horizontal cells to gain control and organization of bipolar and ganglion cell receptive fields can only be evaluated with an in-depth understanding of signal processing in horizontal cells. Therefore, a horizontal slice preparation of the mouse retina was established to record from horizontal cell bodies with their dendritic fields intact and receiving functional synaptic input from cone photoreceptors. Horizontal cell bodies showed spontaneous excitatory currents (spEPSCs) of monophasic and more complex multi-peak waveforms. spEPSCs were induced by quantal release of glutamate from presynaptic cones with a unitary amplitude of 3 pA. Non-stationary noise analysis revealed that spEPSCs with a monoexponential decay were mediated by 7-8 glutamate receptors with a single-channel amplitude of 1.55 pA. Responses to photopic full-field illumination were characterized by reduction of a tonic inward current or hyperpolarization, inhibition of spEPSCs, followed by a fast and transient inward current at light offset. The response to periodic dark/light transitions of different frequencies was dependent on the adaptational status of the cell with a limiting frequency of 10 Hz. Both on and off components of the light response were mediated by AMPA and kainate receptors. Detailed analysis of horizontal cell synaptic physiology is a prerequisite for understanding signal coding and processing at the photoreceptor ribbon synapse.
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Affiliation(s)
- Andreas Feigenspan
- Department of Biology, Division of Animal Physiology, University of Erlangen-Nuernberg, Staudtstrasse 5, D-91058, Erlangen, German
| | - Norbert Babai
- Department of Biology, Division of Animal Physiology, University of Erlangen-Nuernberg, Staudtstrasse 5, D-91058, Erlangen, German
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30
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Disruption of a neural microcircuit in the rod pathway of the mammalian retina by diabetes mellitus. J Neurosci 2015; 35:5422-33. [PMID: 25834065 DOI: 10.1523/jneurosci.5285-14.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Diabetes leads to dysfunction of the neural retina before and independent of classical microvascular diabetic retinopathy, but previous studies have failed to demonstrate which neurons and circuits are affected at the earliest stages. Here, using patch-clamp recording and two-photon Ca(2+) imaging in rat retinal slices, we investigated diabetes-evoked changes in a microcircuit consisting of rod bipolar cells and their dyad postsynaptic targets, AII and A17 amacrine cells, which play an essential role in processing scotopic visual signals. AII amacrines forward their signals to ON- and OFF-cone bipolar cells and A17 amacrines provide GABAergic feedback inhibition to rod bipolar cells. Whereas Ca(2+)-permeable AMPA receptors mediate input from rod bipolar cells to both AII and A17 amacrines, diabetes changes the synaptic receptors on A17, but not AII amacrine cells. This was expressed as a change in pharmacological properties and single-channel conductance of the synaptic receptors, consistent with an upregulation of the AMPA receptor GluA2 subunit and reduced Ca(2+) permeability. In addition, two-photon imaging revealed reduced agonist-evoked influx of Ca(2+) in dendritic varicosities of A17 amacrine cells from diabetic compared with normal animals. Because Ca(2+)-permeable receptors in A17 amacrine cells mediate synaptic release of GABA, the reduced Ca(2+) permeability of these receptors in diabetic animals leads to reduced release of GABA, followed by disinhibition and increased release of glutamate from rod bipolar cells. This perturbation of neuron and microcircuit dynamics can explain the decreased dynamic range and sensitivity of scotopic vision that has been observed in diabetes.
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GABAergic transmission to kisspeptin neurons is differentially regulated by time of day and estradiol in female mice. J Neurosci 2015; 34:16296-308. [PMID: 25471569 DOI: 10.1523/jneurosci.3057-14.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) secretion is regulated by estradiol feedback. This feedback switches from negative to positive in females; this switch depends on time of day in many species. Estradiol feedback is likely conveyed via afferents. Kisspeptin neurons of the arcuate nucleus and anteroventral-periventricular region (AVPV) may differentially regulate GnRH neurons during negative and positive feedback, respectively. We tested estradiol and time of day regulation of GABAergic transmission and postsynaptic response to GABA in these two populations using transgenic mice with GFP-identified kisspeptin neurons. Ovariectomized (OVX) mice treated or not with estradiol (E) were studied in the AM (negative feedback) or PM (positive feedback). GABAA receptor reversal potential was unaffected by time of day or estradiol. GABA depolarized the membrane potential of arcuate neurons from OVX+E mice; this response was blunted in cells from OVX mice. GABA hyperpolarized AVPV kisspeptin neurons, except in the OVX PM group in which GABA did not alter membrane potential attributable to a PM hyperpolarization of baseline membrane potential. In both kisspeptin neuron populations from OVX mice, the frequency of GABAergic spontaneous postsynaptic currents was increased in the PM; this increase was blunted by estradiol. In arcuate, but not AVPV, kisspeptin neurons, estradiol reduced miniature postsynaptic current amplitude independent of time of day. Using nonstationary fluctuation analysis and diazepam to manipulate GABAA receptor apparent affinity, the decrease in arcuate miniature postsynaptic current amplitude was attributed to decreased number of receptors bound by GABA. Time of day and estradiol feedback thus both target presynaptic and postsynaptic mechanisms to differentially regulate kisspeptin neurons via GABAergic transmission.
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Target-specific properties of thalamocortical synapses onto layer 4 of mouse primary visual cortex. J Neurosci 2015; 34:15455-65. [PMID: 25392512 DOI: 10.1523/jneurosci.2595-14.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In primary sensory cortices, thalamocortical (TC) inputs can directly activate excitatory and inhibitory neurons. In vivo experiments in the main input layer (L4) of primary visual cortex (V1) have shown that excitatory and inhibitory neurons have different tuning properties. The different functional properties may arise from distinct intrinsic properties of L4 neurons, but could also depend on cell type-specific properties of the synaptic inputs from the lateral geniculate nucleus of the thalamus (LGN) onto L4 neurons. While anatomical studies identified LGN inputs onto both excitatory and inhibitory neurons in V1, their synaptic properties have not been investigated. Here we used an optogenetic approach to selectively activate LGN terminal fields in acute coronal slices containing V1, and recorded monosynaptic currents from excitatory and inhibitory neurons in L4. LGN afferents made monosynaptic connections with pyramidal (Pyr) and fast-spiking (FS) neurons. TC EPSCs on FS neurons were larger and showed steeper short-term depression in response to repetitive stimulation than those on Pyr neurons. LGN inputs onto Pyr and FS neurons also differed in postsynaptic receptor composition and organization of presynaptic release sites. Together, our results demonstrate that LGN input onto L4 neurons in mouse V1 have target-specific presynaptic and postsynaptic properties. Distinct mechanisms of activation of feedforward excitatory and inhibitory neurons in the main input layer of V1 are likely to endow neurons with different response properties to incoming visual stimuli.
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Rebound potentiation of inhibition in juvenile visual cortex requires vision-induced BDNF expression. J Neurosci 2014; 34:10770-9. [PMID: 25100608 DOI: 10.1523/jneurosci.5454-13.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The developmental increase in the strength of inhibitory synaptic circuits defines the time window of the critical period for plasticity in sensory cortices. Conceptually, plasticity of inhibitory synapses is an attractive mechanism to allow for homeostatic adaptation to the sensory environment. However, a brief duration of visual deprivation that causes maximal change in excitatory synapses produces minimal change in inhibitory synaptic transmission. Here we examined developmental and experience-dependent changes in inhibition by measuring miniature IPSCs (mIPSCs) in layer 2/3 pyramidal neurons of mouse visual cortex. During development from postnatal day 21 (P21) to P35, GABAA receptor function changed from fewer higher-conductance channels to more numerous lower-conductance channels without altering the average mIPSC amplitude. Although a week of visual deprivation did not alter the average mIPSC amplitude, a subsequent 2 h exposure to light produced a rapid rebound potentiation. This form of plasticity is restricted to a critical period before the developmental change in GABAergic synaptic properties is completed, and hence is absent by P35. Visual experience-dependent rebound potentiation of mIPSCs is accompanied by an increase in the open channel number and requires activity-dependent transcription of brain-derived neurotrophic factor (BDNF). Mice lacking BDNF transcription through promoter IV did not show developmental changes in inhibition and lacked rebound potentiation. Our results suggest that sensory experience may have distinct functional consequences in normal versus deprived sensory cortices, and that experience-dependent BDNF expression controls the plasticity of inhibitory synaptic transmission particularly when recovering vision during the critical period.
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Bright DP, Smart TG. Methods for recording and measuring tonic GABAA receptor-mediated inhibition. Front Neural Circuits 2013; 7:193. [PMID: 24367296 PMCID: PMC3852068 DOI: 10.3389/fncir.2013.00193] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/18/2013] [Indexed: 01/12/2023] Open
Abstract
Tonic inhibitory conductances mediated by GABAA receptors have now been identified and characterized in many different brain regions. Most experimental studies of tonic GABAergic inhibition have been carried out using acute brain slice preparations but tonic currents have been recorded under a variety of different conditions. This diversity of recording conditions is likely to impact upon many of the factors responsible for controlling tonic inhibition and can make comparison between different studies difficult. In this review, we will firstly consider how various experimental conditions, including age of animal, recording temperature and solution composition, are likely to influence tonic GABAA conductances. We will then consider some technical considerations related to how the tonic conductance is measured and subsequently analyzed, including how the use of current noise may provide a complementary and reliable method for quantifying changes in tonic current.
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Affiliation(s)
- Damian P Bright
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
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Differential subcellular targeting of glutamate receptor subtypes during homeostatic synaptic plasticity. J Neurosci 2013; 33:13547-59. [PMID: 23946413 DOI: 10.1523/jneurosci.1873-13.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Homeostatic processes are believed to contribute to the stability of neuronal networks that are perpetually influenced by Hebbian forms of synaptic plasticity. Whereas the rules governing the targeting and trafficking of AMPA and NMDA subtypes of glutamate receptors during rapid Hebbian LTP have been extensively studied, those that are operant during homeostatic forms of synaptic strengthening are less well understood. Here, we used biochemical, biophysical, and pharmacological approaches to investigate glutamate receptor regulation during homeostatic synaptic plasticity. We show in rat organotypic hippocampal slices that prolonged network silencing induced a robust surface upregulation of GluA2-lacking AMPARs, not only at synapses, but also at extrasynaptic dendritic and somatic regions of CA1 pyramidal neurons. We also detected a shift in NMDAR subunit composition that, in contrast to the cell-wide surface delivery of GluA2-lacking AMPARs, occurred exclusively at synapses. The subunit composition and subcellular distribution of AMPARs and NMDARs are therefore distinctly regulated during homeostatic synaptic plasticity. Thus, because subunit composition dictates key channel properties, such as agonist affinity, gating kinetics, and calcium permeability, the homeostatic synaptic process transcends the simple modulation of synaptic strength by also regulating the signaling and integrative properties of central synapses.
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Target-specific IPSC kinetics promote temporal processing in auditory parallel pathways. J Neurosci 2013; 33:1598-614. [PMID: 23345233 DOI: 10.1523/jneurosci.2541-12.2013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The acoustic environment contains biologically relevant information on timescales from microseconds to tens of seconds. The auditory brainstem nuclei process this temporal information through parallel pathways that originate in the cochlear nucleus from different classes of cells. Although the roles of ion channels and excitatory synapses in temporal processing have been well studied, the contribution of inhibition is less well understood. Here, we show in CBA/CaJ mice that the two major projection neurons of the ventral cochlear nucleus, the bushy and T-stellate cells, receive glycinergic inhibition with different synaptic conductance time courses. Bushy cells, which provide precisely timed spike trains used in sound localization and pitch identification, receive slow inhibitory inputs. In contrast, T-stellate cells, which encode slower envelope information, receive inhibition that is eightfold faster. Both types of inhibition improved the precision of spike timing but engage different cellular mechanisms and operate on different timescales. Computer models reveal that slow IPSCs in bushy cells can improve spike timing on the scale of tens of microseconds. Although fast and slow IPSCs in T-stellate cells improve spike timing on the scale of milliseconds, only fast IPSCs can enhance the detection of narrowband acoustic signals in a complex background. Our results suggest that target-specific IPSC kinetics are critical for the segregated parallel processing of temporal information from the sensory environment.
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Distinct sensory requirements for unimodal and cross-modal homeostatic synaptic plasticity. J Neurosci 2012; 32:8469-74. [PMID: 22723686 DOI: 10.1523/jneurosci.1424-12.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Loss of a sensory modality elicits both unimodal changes in the deprived cortex and cross-modal alterations in the remaining sensory systems. Unimodal changes are proposed to recruit the deprived cortex for processing the remaining senses, while cross-modal changes are thought to refine processing of spared senses. Hence coordinated unimodal and cross-modal changes are likely beneficial. Despite this expectation, we report in mice that losing behaviorally relevant patterned vision is sufficient to trigger cross-modal synaptic changes in the primary somatosensory cortex barrel fields, but is insufficient to drive unimodal synaptic plasticity in visual cortex (V1), which requires a complete loss of visual activity. In addition, cross-modal changes depend on whisker inputs. Our results demonstrate that unimodal and cross-modal synaptic plasticity occur independently of each other and rely on distinct sensory requirements.
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CREB-dependent transcriptional control and quantal changes in persistent long-term potentiation in hippocampal interneurons. J Neurosci 2012; 32:6335-50. [PMID: 22553039 DOI: 10.1523/jneurosci.5463-11.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mounting evidence indicates an important role of long-term synaptic plasticity in hippocampal inhibitory interneurons in learning and memory. The cellular and molecular mechanisms that underlie such persistent changes in synaptic function in interneurons remain, however, largely undetermined. A transcription- and translation-dependent form of long-term potentiation was uncovered at excitatory synapses onto hippocampal interneurons in oriens-alveus (OA-INs) which is induced by activation of type 1 metabotropic glutamate receptors (cL-LTP(mGluR1)). Here, we use (1) a combination of pharmacological siRNA knock-down and overexpression approaches to reveal the molecular mechanisms of transcriptional control via cAMP response element-binding protein (CREB) during induction, and (2) quantal analysis to identify synaptic changes during maintenance of cL-LTP(mGluR1) in rat hippocampus. Induction stimulated CREB phosphorylation in OA-INs via extracellular signal-regulated protein kinase (ERK) signaling. Also, CREB knockdown impaired cL-LTP(mGluR1), whereas CREB overexpression facilitated the induction, demonstrating a necessary and permissive role of CREB via ERK signaling in transcriptional control in cL-LTP(mGluR1). Quantal analysis of synaptic responses during cL-LTP(mGluR1) maintenance revealed an increased number of quanta released, corresponding to enhanced transmitter release and a larger quantal size, indicating enhanced responsiveness to individual quanta. Fluctuation analysis of synaptic currents uncovered an increase in conductance and number of functional postsynaptic receptors contributing to single quanta. Our findings indicate that CREB-dependent transcription is a necessary permissive switch for eliciting persistent presynaptic and postsynaptic quantal changes at excitatory synapses in inhibitory local circuits, uncovering cell type-specific coupling of induction and expression mechanisms during persistent synaptic plasticity which may contribute to hippocampal long-term memory processes.
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Marty VN, Spigelman I. Long-lasting alterations in membrane properties, k(+) currents, and glutamatergic synaptic currents of nucleus accumbens medium spiny neurons in a rat model of alcohol dependence. Front Neurosci 2012; 6:86. [PMID: 22701402 PMCID: PMC3370662 DOI: 10.3389/fnins.2012.00086] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/22/2012] [Indexed: 01/19/2023] Open
Abstract
Chronic alcohol exposure causes marked changes in reinforcement mechanisms and motivational state that are thought to contribute to the development of cravings and relapse during protracted withdrawal. The nucleus accumbens (NAcc) is a key structure of the mesolimbic dopaminergic reward system. Although the NAcc plays an important role in mediating alcohol-seeking behaviors, little is known about the molecular mechanisms underlying alcohol-induced neuroadaptive changes in NAcc function. The aim of this study was to investigate the effects of chronic intermittent ethanol (CIE) treatment, a rat model of alcohol withdrawal and dependence, on intrinsic electrical membrane properties and glutamatergic synaptic transmission of medium spiny neurons (MSNs) in the NAcc core during protracted withdrawal. We show that CIE treatment followed by prolonged withdrawal increased the inward rectification of MSNs observed at hyperpolarized potentials. In addition, MSNs from CIE-treated animals displayed a lower input resistance, faster action potentials (APs), and larger fast afterhyperpolarizations (fAHPs) than MSNs from vehicle-treated animals, all suggestive of increases in K(+)-channel conductances. Significant increases in the Cs(+)-sensitive inwardly rectifying K(+)-current accounted for the increased input resistance, while increases in the A-type K(+)-current accounted for the faster APs and increased fAHPs in MSNs from CIE rats. We also show that the amplitude and the conductance of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated mEPSCs were enhanced in CIE-treated animals due to an increase in a small fraction of functional postsynaptic GluA2-lacking AMPARs. These long-lasting modifications of excitability and excitatory synaptic receptor function of MSNs in the NAcc core could play a critical role in the neuroadaptive changes underlying alcohol withdrawal and dependence.
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Affiliation(s)
- Vincent N Marty
- Division of Oral Biology and Medicine, School of Dentistry, University of California Los Angeles, CA, USA
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Kueh S, Dempster J, Head S, Morley J. Reduced postsynaptic GABAA receptor number and enhanced gaboxadol induced change in holding currents in Purkinje cells of the dystrophin-deficient mdx mouse. Neurobiol Dis 2011; 43:558-64. [DOI: 10.1016/j.nbd.2011.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 04/18/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022] Open
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Abstract
Acid-sensing ion channels (ASICs), a member of the degenerin/epithelial Na+ channel superfamily, are widely expressed in the mammalian CNS. Accumulating evidence suggests that ASIC current density is higher in GABAergic interneurons than that in glutamatergic pyramidal neurons (PNs) in the hippocampus. Such differential expression of ASICs in cortical networks is thought to be a key element for seizure termination. However, GABAergic interneurons are highly diverse; it is unclear whether the functional expression of ASICs differs in distinct GABAergic interneuron subtypes. Moreover, the subunit composition of ASICs in individual GABAergic interneurons remains unknown. By combining patch-clamp recording and single-cell reverse transcription (RT)-PCR analysis, we correlated ASIC currents with their gene expression in acute rat hippocampal slices. The results yielded several surprising findings. First, ASIC current density of oriens lacunosum-moleculare (O-LM) cells in the CA1 region, a classical type of dendrite-targeting interneuron, is 6 times greater than that of fast-spiking basket cells (BCs) in the dentate gyrus, a major class of soma-targeting interneuron. Second, the recovery of ASICs from desensitization is slowest in BCs, intermediate in PNs, and fastest in O-LM cells. Third, the tarantula venom psalmotoxin 1, the specific blocker for ASIC1a homomers, inhibits ASIC currents in BCs but not in O-LM cells. Finally, single-cell RT-PCR analysis reveals coexpression of ASIC1a and ASIC2 subunit transcripts in O-LM cells, whereas only ASIC1a subunit transcript is detected in most BCs. Thus, differential expression of ASICs in inhibitory microcircuits likely contributes to the distinct roles of GABAergic interneurons in normal physiology and pathophysiology.
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Goodchild SJ, Lamy C, Seutin V, Marrion NV. Inhibition of K(Ca)2.2 and K(Ca)2.3 channel currents by protonation of outer pore histidine residues. ACTA ACUST UNITED AC 2010; 134:295-308. [PMID: 19786583 PMCID: PMC2757770 DOI: 10.1085/jgp.200910252] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ion channels are often modulated by changes in extracellular pH, with most examples resulting from shifts in the ionization state of histidine residue(s) in the channel pore. The application of acidic extracellular solution inhibited expressed K(Ca)2.2 (SK2) and K(Ca)2.3 (SK3) channel currents, with K(Ca)2.3 (pIC(50) of approximately 6.8) being approximately fourfold more sensitive than K(Ca)2.2 (pIC(50) of approximately 6.2). Inhibition was found to be voltage dependent, resulting from a shift in the affinity for the rectifying intracellular divalent cation(s) at the inner mouth of the selectivity filter. The inhibition by extracellular protons resulted from a reduction in the single-channel conductance, without significant changes in open-state kinetics or open probability. K(Ca)2.2 and K(Ca)2.3 subunits both possess a histidine residue in their outer pore region between the transmembrane S5 segment and the pore helix, with K(Ca)2.3 also exhibiting an additional histidine residue between the selectivity filter and S6. Mutagenesis revealed that the outer pore histidine common to both channels was critical for inhibition. The greater sensitivity of K(Ca)2.3 currents to protons arose from the additional histidine residue in the pore, which was more proximal to the conduction pathway and in the electrostatic vicinity of the ion conduction pathway. The decrease of channel conductance by extracellular protons was mimicked by mutation of the outer pore histidine in K(Ca)2.2 to an asparagine residue. These data suggest that local interactions involving the outer turret histidine residues are crucial to enable high conductance openings, with protonation inhibiting current by changing pore shape.
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Affiliation(s)
- Samuel J Goodchild
- Department of Physiology and Pharmacology, University of Bristol, England, UK
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Broky J, Douglass KM, Ellis J, Dogariu A. Fluctuations of scattered waves: going beyond the ensemble average. OPTICS EXPRESS 2009; 17:10466-10471. [PMID: 19550442 DOI: 10.1364/oe.17.010466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interaction between coherent waves and random media is a complicated, deterministic process that is usually examined upon ensemble averaging. The result of one realization of the interaction process depends on the specific disorder present in an experimentally controllable interaction volume. We show that this randomness can be quantified and structural information not apparent in the ensemble average can be obtained. We use the information entropy as a viable measure of randomness and we demonstrate that its rate of change provides means for discriminating between media with identical mean characteristics.
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Affiliation(s)
- J Broky
- College of Optics and Photonics, CREOL, University of Central Florida, Orlando, Florida 32816, USA
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Mørkve SH, Hartveit E. Properties of glycine receptors underlying synaptic currents in presynaptic axon terminals of rod bipolar cells in the rat retina. J Physiol 2009; 587:3813-30. [PMID: 19528247 DOI: 10.1113/jphysiol.2009.173583] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The excitability of presynaptic terminals can be controlled by synaptic input that directly targets the terminals. Retinal rod bipolar axon terminals receive presynaptic input from different types of amacrine cells, some of which are glycinergic. Here, we have performed patch-clamp recordings from rod bipolar axon terminals in rat retinal slices. We used whole-cell recordings to study glycinergic inhibitory postsynaptic currents (IPSCs) under conditions of adequate local voltage clamp and outside-out patch recordings to study biophysical and pharmacological properties of the glycine receptors with ultrafast application. Glycinergic IPSCs, recorded in both intact cells and isolated terminals, were strychnine sensitive and displayed fast kinetics with a double-exponential decay. Ultrafast application of brief (approximately 1 ms) pulses of glycine (3 mM) to patches evoked responses with fast, double-exponential deactivation kinetics, no evidence of desensitization in double-pulse experiments, relatively low apparent affinity (EC(50) approximately 100 microM), and high maximum open probability (0.9). Longer pulses evoked slow, double-exponential desensitization and double-pulse experiments indicated slow, double-exponential recovery from desensitization. Non-stationary noise analysis of IPSCs and patch responses yielded single-channel conductances of approximately 41 pS and approximately 64 pS, respectively. Directly observed single-channel gating occurred at approximately 40-50 pS and approximately 80-90 pS in both types of responses, suggesting a mixture of heteromeric and homomeric receptors. Synaptic release of glycine leads to transient receptor activation, with about eight receptors available to bind transmitter after release of a single vesicle. With a low intracellular chloride concentration, this leads to either hyperpolarizing or shunting inhibition that will counteract passive and regenerative depolarization and depolarization-evoked transmitter release.
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Affiliation(s)
- Svein Harald Mørkve
- University of Bergen, Department of Biomedicine, Jonas Lies vei 91, N-5009 Bergen, Norway.
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Low-conductance HCN1 ion channels augment the frequency response of rod and cone photoreceptors. J Neurosci 2009; 29:5841-53. [PMID: 19420251 DOI: 10.1523/jneurosci.5746-08.2009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels are expressed in several tissues throughout the body, including the heart, the CNS, and the retina. HCN channels are found in many neurons in the retina, but their most established role is in generating the hyperpolarization-activated current, I(h), in photoreceptors. This current makes the light response of rod and cone photoreceptors more transient, an effect similar to that of a high-pass filter. A unique property of HCN channels is their small single-channel current, which is below the thermal noise threshold of measuring electronics. We use nonstationary fluctuation analysis (NSFA) in the intact retina to estimate the conductance of single HCN channels, revealing a conductance of approximately 650 fS in both rod and cone photoreceptors. We also analyze the properties of HCN channels in salamander rods and cones, from the biophysical to the functional level, showing that HCN1 is the predominant isoform in both cells, and demonstrate how HCN1 channels speed up the light response of both rods and cones under distinct adaptational conditions. We show that in rods and cones, HCN channels increase the natural frequency response of single cells by modifying the photocurrent input, which is limited in its frequency response by the speed of a molecular signaling cascade. In doing so, HCN channels form the first of several systems in the retina that augment the speed of the visual response, allowing an animal to perceive visual stimuli that change more quickly than the underlying photocurrent.
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Paired-recordings from synaptically coupled cortical and hippocampal neurons in acute and cultured brain slices. Nat Protoc 2008; 3:1559-68. [PMID: 18802437 DOI: 10.1038/nprot.2008.147] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Analysis of synaptic transmission, synaptic plasticity, axonal processing, synaptic timing or electrical coupling requires the simultaneous recording of both the pre- and postsynaptic compartments. Paired-recording technique of monosynaptically connected neurons is also an appropriate technique to probe the function of small molecules (calcium buffers, peptides or small proteins) at presynaptic terminals that are too small to allow direct whole-cell patch-clamp recording. We describe here a protocol for obtaining, in acute and cultured slices, synaptically connected pairs of cortical and hippocampal neurons, with a reasonably high probability. The protocol includes four main stages (acute/cultured slice preparation, visualization, recording and analysis) and can be completed in approximately 4 h.
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