1
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Park P, Wong-Campos D, Itkis DG, Lee BH, Qi Y, Davis H, Antin B, Pasarkar A, Grimm JB, Plutkis SE, Holland KL, Paninski L, Lavis LD, Cohen AE. Dendritic excitations govern back-propagation via a spike-rate accelerometer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.02.543490. [PMID: 37398232 PMCID: PMC10312650 DOI: 10.1101/2023.06.02.543490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Dendrites on neurons support nonlinear electrical excitations, but the computational significance of these events is not well understood. We developed molecular, optical, and analytical tools to map sub-millisecond voltage dynamics throughout the dendritic trees of CA1 pyramidal neurons under diverse optogenetic and synaptic stimulus patterns, in acute brain slices. We observed history-dependent spike back-propagation in distal dendrites, driven by locally generated Na+ spikes (dSpikes). Dendritic depolarization created a transient window for dSpike propagation, opened by A-type K V channel inactivation, and closed by slow N a V inactivation. Collisions of dSpikes with synaptic inputs triggered calcium channel and N-methyl-D-aspartate receptor (NMDAR)-dependent plateau potentials, with accompanying complex spikes at the soma. This hierarchical ion channel network acts as a spike-rate accelerometer, providing an intuitive picture of how dendritic excitations shape associative plasticity rules.
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Affiliation(s)
- Pojeong Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - David Wong-Campos
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Daniel G Itkis
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Byung Hun Lee
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Yitong Qi
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Hunter Davis
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Benjamin Antin
- Departments of Statistics and Neuroscience, Columbia University, New York, NY, USA
| | - Amol Pasarkar
- Departments of Statistics and Neuroscience, Columbia University, New York, NY, USA
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Sarah E Plutkis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Katie L Holland
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Liam Paninski
- Departments of Statistics and Neuroscience, Columbia University, New York, NY, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Adam E Cohen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
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2
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Andreyanov M, Heinrich R, Berlin S. Design of Ultrapotent Genetically Encoded Inhibitors of Kv4.2 for Gating Neural Plasticity. J Neurosci 2024; 44:e2295222023. [PMID: 38154956 PMCID: PMC10869153 DOI: 10.1523/jneurosci.2295-22.2023] [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: 12/15/2022] [Revised: 11/05/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
The Kv4.2 potassium channel plays established roles in neuronal excitability, while also being implicated in plasticity. Current means to study the roles of Kv4.2 are limited, motivating us to design a genetically encoded membrane tethered Heteropodatoxin-2 (MetaPoda). We find that MetaPoda is an ultrapotent and selective gating-modifier of Kv4.2. We narrow its site of contact with the channel to two adjacent residues within the voltage sensitive domain (VSD) and, with docking simulations, suggest that the toxin binds the VSD from within the membrane. We also show that MetaPoda does not require an external linker of the channel for its activity. In neurons (obtained from female and male rat neonates), MetaPoda specifically, and potently, inhibits all Kv4 currents, leaving all other A-type currents unaffected. Inhibition of Kv4 in hippocampal neurons does not promote excessive excitability, as is expected from a simple potassium channel blocker. We do find that MetaPoda's prolonged expression (1 week) increases expression levels of the immediate early gene cFos and prevents potentiation. These findings argue for a major role of Kv4.2 in facilitating plasticity of hippocampal neurons. Lastly, we show that our engineering strategy is suitable for the swift engineering of another potent Kv4.2-selective membrane-tethered toxin, Phrixotoxin-1, denoted MetaPhix. Together, we provide two uniquely potent genetic tools to study Kv4.2 in neuronal excitability and plasticity.
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Affiliation(s)
- Michael Andreyanov
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
| | - Ronit Heinrich
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
| | - Shai Berlin
- Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa 3525433, Israel
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Parkins EV, Brager DH, Rymer JK, Burwinkel JM, Rojas D, Tiwari D, Hu YC, Gross C. Mir324 knockout regulates the structure of dendritic spines and impairs hippocampal long-term potentiation. Sci Rep 2023; 13:21919. [PMID: 38082035 PMCID: PMC10713680 DOI: 10.1038/s41598-023-49134-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 12/04/2023] [Indexed: 12/18/2023] Open
Abstract
MicroRNAs are an emerging class of synaptic regulators. These small noncoding RNAs post-transcriptionally regulate gene expression, thereby altering neuronal pathways and shaping cell-to-cell communication. Their ability to rapidly alter gene expression and target multiple pathways makes them interesting candidates in the study of synaptic plasticity. Here, we demonstrate that the proconvulsive microRNA miR-324-5p regulates excitatory synapse structure and function in the hippocampus of mice. Both Mir324 knockout (KO) and miR-324-5p antagomir treatment significantly reduce dendritic spine density in the hippocampal CA1 subregion, and Mir324 KO, but not miR-324-5p antagomir treatment, shift dendritic spine morphology, reducing the proportion of thin, "unstable" spines. Western blot and quantitative Real-Time PCR revealed changes in protein and mRNA levels for potassium channels, cytoskeletal components, and synaptic markers, including MAP2 and Kv4.2, which are important for long-term potentiation (LTP). In line with these findings, slice electrophysiology revealed that LTP is severely impaired in Mir324 KO mice, while neurotransmitter release probability remains unchanged. Overall, this study demonstrates that miR-324-5p regulates dendritic spine density, morphology, and plasticity in the hippocampus, potentially via multiple cytoskeletal and synaptic modulators.
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Affiliation(s)
- Emma V Parkins
- University of Cincinnati Neuroscience Graduate Program, Cincinnati, OH, 45229, USA
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Darrin H Brager
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, USA
| | - Jeffrey K Rymer
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - John M Burwinkel
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Diego Rojas
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Durgesh Tiwari
- University of Cincinnati Neuroscience Graduate Program, Cincinnati, OH, 45229, USA
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Yueh-Chiang Hu
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
- Transgenic Animal and Genome Editing Core Facility, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Christina Gross
- University of Cincinnati Neuroscience Graduate Program, Cincinnati, OH, 45229, USA.
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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4
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Nomura T, Taniguchi S, Wang YZ, Yeh NH, Wilen AP, Castillon CCM, Foote KM, Xu J, Armstrong JN, Savas JN, Swanson GT, Contractor A. A Pathogenic Missense Mutation in Kainate Receptors Elevates Dendritic Excitability and Synaptic Integration through Dysregulation of SK Channels. J Neurosci 2023; 43:7913-7928. [PMID: 37802657 PMCID: PMC10669804 DOI: 10.1523/jneurosci.1259-23.2023] [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: 07/07/2023] [Revised: 09/12/2023] [Accepted: 09/16/2023] [Indexed: 10/08/2023] Open
Abstract
Numerous rare variants that cause neurodevelopmental disorders (NDDs) occur within genes encoding synaptic proteins, including ionotropic glutamate receptors. However, in many cases, it remains unclear how damaging missense variants affect brain function. We determined the physiological consequences of an NDD causing missense mutation in the GRIK2 kainate receptor (KAR) gene, that results in a single amino acid change p.Ala657Thr in the GluK2 receptor subunit. We engineered this mutation in the mouse Grik2 gene, yielding a GluK2(A657T) mouse, and studied mice of both sexes to determine how hippocampal neuronal function is disrupted. Synaptic KAR currents in hippocampal CA3 pyramidal neurons from heterozygous A657T mice exhibited slow decay kinetics, consistent with incorporation of the mutant subunit into functional receptors. Unexpectedly, CA3 neurons demonstrated elevated action potential spiking because of downregulation of the small-conductance Ca2+ activated K+ channel (SK), which mediates the post-spike afterhyperpolarization. The reduction in SK activity resulted in increased CA3 dendritic excitability, increased EPSP-spike coupling, and lowered the threshold for the induction of LTP of the associational-commissural synapses in CA3 neurons. Pharmacological inhibition of SK channels in WT mice increased dendritic excitability and EPSP-spike coupling, mimicking the phenotype in A657T mice and suggesting a causative role for attenuated SK activity in aberrant excitability observed in the mutant mice. These findings demonstrate that a disease-associated missense mutation in GRIK2 leads to altered signaling through neuronal KARs, pleiotropic effects on neuronal and dendritic excitability, and implicate these processes in neuropathology in patients with genetic NDDs.SIGNIFICANCE STATEMENT Damaging mutations in genes encoding synaptic proteins have been identified in various neurodevelopmental disorders, but the functional consequences at the cellular and circuit level remain elusive. By generating a novel knock-in mutant mouse, this study examined the role of a pathogenic mutation in the GluK2 kainate receptor (KAR) subunit, a subclass of ionotropic glutamate receptors. Analyses of hippocampal CA3 pyramidal neurons determined elevated action potential firing because of an increase in dendritic excitability. Increased dendritic excitability was attributable to reduced activity of a Ca2+ activated K+ channel. These results indicate that a pathogenic KAR mutation results in dysregulation of dendritic K+ channels, which leads to an increase in synaptic integration and backpropagation of action potentials into distal dendrites.
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Affiliation(s)
- Toshihiro Nomura
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Sakiko Taniguchi
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Yi-Zhi Wang
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Nai-Hsing Yeh
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Anika P Wilen
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Charlotte C M Castillon
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Kendall M Foote
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Jian Xu
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - John N Armstrong
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Jeffrey N Savas
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Geoffrey T Swanson
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Neurobiology, Weinberg College of Arts and Sciences Northwestern University, Chicago, Illinois 60611
| | - Anis Contractor
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Psychiatry and Behavioral Sciences Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Neurobiology, Weinberg College of Arts and Sciences Northwestern University, Chicago, Illinois 60611
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5
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Mishra P, Narayanan R. The enigmatic HCN channels: A cellular neurophysiology perspective. Proteins 2023. [PMID: 37982354 DOI: 10.1002/prot.26643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/24/2023] [Accepted: 11/09/2023] [Indexed: 11/21/2023]
Abstract
What physiological role does a slow hyperpolarization-activated ion channel with mixed cation selectivity play in the fast world of neuronal action potentials that are driven by depolarization? That puzzling question has piqued the curiosity of physiology enthusiasts about the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are widely expressed across the body and especially in neurons. In this review, we emphasize the need to assess HCN channels from the perspective of how they respond to time-varying signals, while also accounting for their interactions with other co-expressing channels and receptors. First, we illustrate how the unique structural and functional characteristics of HCN channels allow them to mediate a slow negative feedback loop in the neurons that they express in. We present the several physiological implications of this negative feedback loop to neuronal response characteristics including neuronal gain, voltage sag and rebound, temporal summation, membrane potential resonance, inductive phase lead, spike triggered average, and coincidence detection. Next, we argue that the overall impact of HCN channels on neuronal physiology critically relies on their interactions with other co-expressing channels and receptors. Interactions with other channels allow HCN channels to mediate intrinsic oscillations, earning them the "pacemaker channel" moniker, and to regulate spike frequency adaptation, plateau potentials, neurotransmitter release from presynaptic terminals, and spike initiation at the axonal initial segment. We also explore the impact of spatially non-homogeneous subcellular distributions of HCN channels in different neuronal subtypes and their interactions with other channels and receptors. Finally, we discuss how plasticity in HCN channels is widely prevalent and can mediate different encoding, homeostatic, and neuroprotective functions in a neuron. In summary, we argue that HCN channels form an important class of channels that mediate a diversity of neuronal functions owing to their unique gating kinetics that made them a puzzle in the first place.
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Affiliation(s)
- Poonam Mishra
- Department of Neuroscience, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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6
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Srikanth S, Narayanan R. Heterogeneous off-target impact of ion-channel deletion on intrinsic properties of hippocampal model neurons that self-regulate calcium. Front Cell Neurosci 2023; 17:1241450. [PMID: 37904732 PMCID: PMC10613471 DOI: 10.3389/fncel.2023.1241450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 09/20/2023] [Indexed: 11/01/2023] Open
Abstract
How do neurons that implement cell-autonomous self-regulation of calcium react to knockout of individual ion-channel conductances? To address this question, we used a heterogeneous population of 78 conductance-based models of hippocampal pyramidal neurons that maintained cell-autonomous calcium homeostasis while receiving theta-frequency inputs. At calcium steady-state, we individually deleted each of the 11 active ion-channel conductances from each model. We measured the acute impact of deleting each conductance (one at a time) by comparing intrinsic electrophysiological properties before and immediately after channel deletion. The acute impact of deleting individual conductances on physiological properties (including calcium homeostasis) was heterogeneous, depending on the property, the specific model, and the deleted channel. The underlying many-to-many mapping between ion channels and properties pointed to ion-channel degeneracy. Next, we allowed the other conductances (barring the deleted conductance) to evolve towards achieving calcium homeostasis during theta-frequency activity. When calcium homeostasis was perturbed by ion-channel deletion, post-knockout plasticity in other conductances ensured resilience of calcium homeostasis to ion-channel deletion. These results demonstrate degeneracy in calcium homeostasis, as calcium homeostasis in knockout models was implemented in the absence of a channel that was earlier involved in the homeostatic process. Importantly, in reacquiring homeostasis, ion-channel conductances and physiological properties underwent heterogenous plasticity (dependent on the model, the property, and the deleted channel), even introducing changes in properties that were not directly connected to the deleted channel. Together, post-knockout plasticity geared towards maintaining homeostasis introduced heterogenous off-target effects on several channels and properties, suggesting that extreme caution be exercised in interpreting experimental outcomes involving channel knockouts.
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Affiliation(s)
- Sunandha Srikanth
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
- Undergraduate Program, Indian Institute of Science, Bangalore, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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7
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Zhao J, Bang S, Furutani K, McGinnis A, Jiang C, Roberts A, Donnelly CR, He Q, James ML, Berger M, Ko MC, Wang H, Palmiter RD, Ji RR. PD-L1/PD-1 checkpoint pathway regulates hippocampal neuronal excitability and learning and memory behavior. Neuron 2023; 111:2709-2726.e9. [PMID: 37348508 PMCID: PMC10529885 DOI: 10.1016/j.neuron.2023.05.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 02/15/2023] [Accepted: 05/25/2023] [Indexed: 06/24/2023]
Abstract
Programmed death protein 1 (PD-1) and its ligand PD-L1 constitute an immune checkpoint pathway. We report that neuronal PD-1 signaling regulates learning/memory in health and disease. Mice lacking PD-1 (encoded by Pdcd1) exhibit enhanced long-term potentiation (LTP) and memory. Intraventricular administration of anti-mouse PD-1 monoclonal antibody (RMP1-14) potentiated learning and memory. Selective deletion of PD-1 in excitatory neurons (but not microglia) also enhances LTP and memory. Traumatic brain injury (TBI) impairs learning and memory, which is rescued by Pdcd1 deletion or intraventricular PD-1 blockade. Conversely, re-expression of Pdcd1 in PD-1-deficient hippocampal neurons suppresses memory and LTP. Exogenous PD-L1 suppresses learning/memory in mice and the excitability of mouse and NHP hippocampal neurons through PD-1. Notably, neuronal activation suppresses PD-L1 secretion, and PD-L1/PD-1 signaling is distinctly regulated by learning and TBI. Thus, conditions that reduce PD-L1 levels or PD-1 signaling could promote memory in both physiological and pathological conditions.
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Affiliation(s)
- Junli Zhao
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Sangsu Bang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Kenta Furutani
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Aidan McGinnis
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Changyu Jiang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Alexus Roberts
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Christopher R Donnelly
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Qianru He
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Michael L James
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Miles Berger
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
| | - Haichen Wang
- Department of Neurology, Duke University Medical Center, Durham, NC 27710, USA
| | - Richard D Palmiter
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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8
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Bellotti AA, Murphy JG, O’Leary TS, Hoffman DA. Transport between im/mobile fractions shapes the speed and profile of cargo distribution in neurons. BIOPHYSICAL REPORTS 2022; 2:100082. [PMID: 36425667 PMCID: PMC9680811 DOI: 10.1016/j.bpr.2022.100082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/13/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
Neuronal function requires continuous distribution of ion channels and other proteins throughout large cell morphologies. Protein distribution is complicated by immobilization of freely diffusing subunits such as on lipid rafts or in postsynaptic densities. Here, we infer rates of immobilization for the voltage-gated potassium channel Kv4.2. Fluorescence recovery after photobleaching quantifies protein diffusion kinetics, typically reported as a recovery rate and mobile fraction. We show that, implicit in the fluorescence recovery, are rates of particle transfer between mobile and immobile fractions (im/mobilization). We performed photobleaching of fluorescein-tagged ion channel Kv4.2-sGFP2 in over 450 dendrites of rat hippocampal cells. Using mass-action models, we infer rates of Kv4.2-sGFP2 im/mobilization. Using a realistic neuron morphology, we show how these rates shape the speed and profile of subunit distribution. The experimental protocol and model inference introduced here is widely applicable to other cargo and experimental systems.
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Affiliation(s)
- Adriano A. Bellotti
- Department of Engineering, University of Cambridge, Cambridge, UK
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Jonathan G. Murphy
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | | | - Dax A. Hoffman
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
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9
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Hu JH, Liu Y, Hoffman DA. Identification of Kv4.2 protein complex and modifications by tandem affinity purification-mass spectrometry in primary neurons. Front Cell Neurosci 2022; 16:1070305. [PMID: 36568885 PMCID: PMC9788671 DOI: 10.3389/fncel.2022.1070305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/24/2022] [Indexed: 12/13/2022] Open
Abstract
Proteins usually form complexes to fulfill variable physiological functions. In neurons, communication relies on synapses where receptors, channels, and anchoring proteins form complexes to precisely control signal transduction, synaptic integration, and action potential firing. Although there are many published protocols to isolate protein complexes in cell lines, isolation in neurons has not been well established. Here we introduce a method that combines lentiviral protein expression with tandem affinity purification followed by mass-spectrometry (TAP-MS) to identify protein complexes in neurons. This protocol can also be used to identify post-translational modifications (PTMs) of synaptic proteins. We used the A-type voltage-gated K+ channel subunit Kv4.2 as the target protein. Kv4.2 is highly expressed in the hippocampus where it contributes to learning and memory through its regulation of neuronal excitability and synaptic plasticity. We tagged Kv4.2 with the calmodulin-binding-peptide (CBP) and streptavidin-binding-peptide (SBP) at its C-terminus and expressed it in neurons via lentivirus. Kv4.2 was purified by two-step TAP and samples were analyzed by MS. MS identified two prominently known Kv4.2 interacting proteins [dipeptidyl peptidase like (DPPs) and Kv channel-interacting proteins (KChIPs)] in addition to novel synaptic proteins including glutamate receptors, a calcium channel, and anchoring proteins. Co-immunoprecipitation and colocalization experiments validated the association of Kv4.2 with glutamate receptors. In addition to protein complex identification, we used TAP-MS to identify Kv4.2 phosphorylation sites. Several known and unknown phosphorylation sites were identified. These findings provide a novel path to identify protein-protein interactions and PTMs in neurons and shed light on mechanisms of neuronal signaling potentially involved in the pathology of neurological diseases.
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10
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Griego E, Segura-Villalobos D, Lamas M, Galván EJ. Maternal immune activation increases excitability via downregulation of A-type potassium channels and reduces dendritic complexity of hippocampal neurons of the offspring. Brain Behav Immun 2022; 105:67-81. [PMID: 35803480 DOI: 10.1016/j.bbi.2022.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/29/2022] [Accepted: 07/03/2022] [Indexed: 11/29/2022] Open
Abstract
The epidemiological association between bacterial or viral maternal infections during pregnancy and increased risk for developing psychiatric disorders in offspring is well documented. Numerous rodent and non-human primate studies of viral- or, to a lesser extent, bacterial-induced maternal immune activation (MIA) have documented a series of neurological alterations that may contribute to understanding the pathophysiology of schizophrenia and autism spectrum disorders. Long-term neuronal and behavioral alterations are now ascribed to the effect of maternal proinflammatory cytokines rather than the infection itself. However, detailed electrophysiological alterations in brain areas relevant to psychiatric disorders, such as the dorsal hippocampus, are lacking in response to bacterial-induced MIA. This study determined if electrophysiological and morphological alterations converge in CA1 pyramidal cells (CA1 PC) from the dorsal hippocampus in bacterial-induced MIA offspring. A series of changes in the functional expression of K+ and Na+ ion channels altered the passive and active membrane properties and triggered hyperexcitability of CA1 PC. Contributing to the hyperexcitability, the somatic A-type potassium current (IA) was decreased in MIA CA1 PC. Likewise, the spontaneous glutamatergic and GABAergic inputs were dysregulated and biased toward increased excitation, thereby reshaping the excitation-inhibition balance. Consistent with these findings, the dendritic branching complexity of MIA CA1 PC was reduced. Together, these morphophysiological alterations modify CA1 PC computational capabilities and contribute to explaining cellular alterations that may underlie the cognitive symptoms of MIA-associated psychiatric disorders.
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Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | | | - Mónica Lamas
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | - Emilio J Galván
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico.
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11
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A missense mutation in Kcnc3 causes hippocampal learning deficits in mice. Proc Natl Acad Sci U S A 2022; 119:e2204901119. [PMID: 35881790 PMCID: PMC9351536 DOI: 10.1073/pnas.2204901119] [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] [Indexed: 11/18/2022] Open
Abstract
Although a wide variety of genetic tools has been developed to study learning and memory, the molecular basis of memory encoding remains incompletely understood. Here, we undertook an unbiased approach to identify novel genes critical for memory encoding. From a large-scale, in vivo mutagenesis screen using contextual fear conditioning, we isolated in mice a mutant, named Clueless, with spatial learning deficits. A causative missense mutation (G434V) was found in the voltage-gated potassium channel, subfamily C member 3 (Kcnc3) gene in a region that encodes a transmembrane voltage sensor. Generation of a Kcnc3G434V CRISPR mutant mouse confirmed this mutation as the cause of the learning defects. While G434V had no effect on transcription, translation, or trafficking of the channel, electrophysiological analysis of the G434V mutant channel revealed a complete loss of voltage-gated conductance, a broadening of the action potential, and decreased neuronal firing. Together, our findings have revealed a role for Kcnc3 in learning and memory.
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12
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Exercise Improves Spatial Learning and Memory Performance through the Central GLP-1 Receptors. Behav Neurol 2022; 2022:2900628. [PMID: 35774081 PMCID: PMC9239811 DOI: 10.1155/2022/2900628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 06/05/2022] [Indexed: 11/27/2022] Open
Abstract
The glucagon-like peptide 1 (GLP-1) is a hormone which is produced in the enteroendocrine L-cells in the ileum and the neurons of nucleus tractus solitarius (NTS) in the brain which has numerous metabolic effects. The central GLP-1R's role in cognitive functioning is well known. On the contrary, it has been shown that exercise has positive effects on brain function. So, we decided to elucidate whether the central GLP-1 has a role in memory and learning. Thirty-two rats were used in this experiment in 4 groups. After anesthetizing the rats, the right lateral ventricle was detected, and a cannula was directed to the ventricle. Ten micrograms of exendin-3 or sterile saline, according to the group, was injected via ICV once daily for seven days. The rats in the exercise group considered an exercise period of one hour each day (17 meters per minute) for seven consecutive days. To evaluate the performance of memory and learning, a standard Morris water maze (MWM) tank was utilized. According to the results, the TE-exendin group showed a statistically significant difference from the TE-SAL group in both parameters of latency and time in the zone. In summary, memory and learning were improved by GLP-1R in the exercise group, but not in the sedentary group, which we can hypothesize that exercise can affect memory and learning through this pathway.
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13
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Ye W, Zhao H, Dai Y, Wang Y, Lo YH, Jan LY, Lee CH. Activation and closed-state inactivation mechanisms of the human voltage-gated K V4 channel complexes. Mol Cell 2022; 82:2427-2442.e4. [PMID: 35597238 DOI: 10.1016/j.molcel.2022.04.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/03/2022] [Accepted: 04/24/2022] [Indexed: 12/30/2022]
Abstract
The voltage-gated ion channel activity depends on both activation (transition from the resting state to the open state) and inactivation. Inactivation is a self-restraint mechanism to limit ion conduction and is as crucial to membrane excitability as activation. Inactivation can occur when the channel is open or closed. Although open-state inactivation is well understood, the molecular basis of closed-state inactivation has remained elusive. We report cryo-EM structures of human KV4.2 channel complexes in inactivated, open, and closed states. Closed-state inactivation of KV4 involves an unprecedented symmetry breakdown for pore closure by only two of the four S4-S5 linkers, distinct from known mechanisms of open-state inactivation. We further capture KV4 in a putative resting state, revealing how voltage sensor movements control the pore. Moreover, our structures provide insights regarding channel modulation by KChIP2 and DPP6 auxiliary subunits. Our findings elucidate mechanisms of closed-state inactivation and voltage-dependent activation of the KV4 channel.
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Affiliation(s)
- Wenlei Ye
- Department of Physiology, University of California, San Francisco, CA 94158, USA
| | - Hongtu Zhao
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yaxin Dai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yingdi Wang
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yu-Hua Lo
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA.
| | - Chia-Hsueh Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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14
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Bavan S, Goodkin HP, Papazian DM. Altered Closed State Inactivation Gating in Kv4.2 Channels Results in Developmental and Epileptic Encephalopathies in Human Patients. Hum Mutat 2022; 43:1286-1298. [PMID: 35510384 DOI: 10.1002/humu.24396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 04/27/2022] [Accepted: 05/01/2022] [Indexed: 11/06/2022]
Abstract
Kv4.2 subunits, encoded by KCND2, serve as the pore-forming components of voltage-gated, inactivating ISA K+ channels expressed in the brain. ISA channels inactivate without opening in response to subthreshold excitatory input, temporarily increasing neuronal excitability, the back propagation of action potentials, and Ca2+ influx into dendrites, thereby regulating mechanisms of spike timing-dependent synaptic plasticity. As previously described, a de novo variant in Kv4.2, p.Val404Met, is associated with an infant-onset developmental and epileptic encephalopathy (DEE) in monozygotic twin boys. The p.Val404Met variant enhances inactivation directly from closed states, but dramatically impairs inactivation after channel opening. We now report the identification of a closely related, novel, de novo variant in Kv4.2, p.Val402Leu, in a boy with an early-onset pharmacoresistant epilepsy that evolved to an epileptic aphasia syndrome (Continuous Spike Wave during Sleep Syndrome). Like p.Val404Met, the p.Val402Leu variant increases the rate of inactivation from closed states, but significantly slows inactivation after the pore opens. Although quantitatively the p.Val402Leu mutation alters channel kinetics less dramatically than p.Val404Met, our results strongly support the conclusion that p.Val402Leu and p.Val404Met cause the clinical features seen in the affected individuals and underscore the importance of closed state inactivation in ISA channels in normal brain development and function. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Selvan Bavan
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095-1571.,Labcorp Drug Development, Huntingdon, PE28 4HS, UK
| | - Howard P Goodkin
- Departments of Neurology and Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, 22903
| | - Diane M Papazian
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095-1571
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15
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Glycogen Synthase Kinase 3: Ion Channels, Plasticity, and Diseases. Int J Mol Sci 2022; 23:ijms23084413. [PMID: 35457230 PMCID: PMC9028019 DOI: 10.3390/ijms23084413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 12/15/2022] Open
Abstract
Glycogen synthase kinase 3β (GSK3) is a multifaceted serine/threonine (S/T) kinase expressed in all eukaryotic cells. GSK3β is highly enriched in neurons in the central nervous system where it acts as a central hub for intracellular signaling downstream of receptors critical for neuronal function. Unlike other kinases, GSK3β is constitutively active, and its modulation mainly involves inhibition via upstream regulatory pathways rather than increased activation. Through an intricate converging signaling system, a fine-tuned balance of active and inactive GSK3β acts as a central point for the phosphorylation of numerous primed and unprimed substrates. Although the full range of molecular targets is still unknown, recent results show that voltage-gated ion channels are among the downstream targets of GSK3β. Here, we discuss the direct and indirect mechanisms by which GSK3β phosphorylates voltage-gated Na+ channels (Nav1.2 and Nav1.6) and voltage-gated K+ channels (Kv4 and Kv7) and their physiological effects on intrinsic excitability, neuronal plasticity, and behavior. We also present evidence for how unbalanced GSK3β activity can lead to maladaptive plasticity that ultimately renders neuronal circuitry more vulnerable, increasing the risk for developing neuropsychiatric disorders. In conclusion, GSK3β-dependent modulation of voltage-gated ion channels may serve as an important pharmacological target for neurotherapeutic development.
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16
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Aceto G, Nardella L, Nanni S, Pecci V, Bertozzi A, Colussi C, D'Ascenzo M, Grassi C. Activation of histamine type 2 receptors enhances intrinsic excitability of medium spiny neurons in the nucleus accumbens. J Physiol 2022; 600:2225-2243. [PMID: 35343587 PMCID: PMC9325548 DOI: 10.1113/jp282962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/21/2022] [Indexed: 11/14/2022] Open
Abstract
Abstract Histaminergic neurons are exclusively located in the hypothalamic tuberomammillary nucleus, from where they project to many brain areas including the nucleus accumbens (NAc), a brain area that integrates diverse monoaminergic inputs to coordinate motivated behaviours. While the NAc expresses various histamine receptor subtypes, the mechanisms by which histamine modulates NAc activity are still poorly understood. Using whole‐cell patch‐clamp recordings, we found that pharmacological activation of histamine 2 (H2) receptors elevates the excitability of NAc medium spiny neurons (MSNs), while activation of H1 receptors failed to significantly affect MSN excitability. The evoked firing of MSNs increased after seconds of local H2 agonist administration and remained elevated for minutes. H2 receptor (H2R) activation accelerated subthreshold depolarization in response to current injection, reduced the latency to fire, diminished action potential afterhyperpolarization and increased the action potential half‐width. The increased excitability was protein kinase A‐dependent and associated with decreased A‐type K+ currents. In addition, selective pharmacological inhibition of the Kv4.2 channel, the main molecular determinant of A‐type K+ currents in MSNs, mimicked and occluded the increased excitability induced by H2R activation. Our results indicate that histaminergic transmission in the NAc increases MSN intrinsic excitability through H2R‐dependent modulation of Kv4.2 channels. Activation of H2R will significantly alter spike firing in MSNs in vivo, and this effect could be an important mechanism by which these receptors mediate certain aspects of goal‐induced behaviours. Key points Histamine is synthesized and released by hypothalamic neurons of the tuberomammillary nucleus and serves as a general modulator for whole‐brain activity including the nucleus accumbens. Histamine receptors type 2 (HR2), which are expressed in the nucleus accumbens, couple to Gαs/off proteins which elevate cyclic adenosine monophosphate levels and activate protein kinase A. Whole‐cell patch‐clamp recordings revealed that H2R activation increased the evoked firing in medium spiny neurons of the nucleus accumbens via protein kinase A‐dependent mechanisms. HR2 activation accelerated subthreshold depolarization in response to current injection, reduced the latency to fire, diminished action potential medium after‐hyperpolarization and increased the action potential half‐width. HR2 activation also reduced A‐type potassium current. Selective pharmacological inhibition of the Kv4.2 channel mimicked and occluded the increased excitability induced by H2R activation.
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Affiliation(s)
- Giuseppe Aceto
- Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Roma, Italia.,Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Luca Nardella
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Simona Nanni
- Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Roma, Italia.,Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Valeria Pecci
- Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Alessia Bertozzi
- Istituto di Analisi dei Sistemi ed Informatica "Antonio Ruberti", National Research Council, Rome, Italy
| | - Claudia Colussi
- Istituto di Analisi dei Sistemi ed Informatica "Antonio Ruberti", National Research Council, Rome, Italy
| | - Marcello D'Ascenzo
- Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Roma, Italia.,Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Claudio Grassi
- Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Roma, Italia.,Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
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17
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Kim KH, Oh Y, Liu J, Dababneh S, Xia Y, Kim RY, Kim DK, Ban K, Husain M, Hui CC, Backx PH. Irx5 and transient outward K + currents contribute to transmural contractile heterogeneities in the mouse ventricle. Am J Physiol Heart Circ Physiol 2022; 322:H725-H741. [PMID: 35245131 DOI: 10.1152/ajpheart.00572.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have established that fast transmural gradients of transient outward K+ current (Ito,f) correlate with regional differences in action potential (AP) profile and excitation-contraction coupling (ECC) with high Ito,f expression in the epimyocardium (EPI) being associated with short APs and low contractility and vice versa. Herein, we investigated the effects of disrupted Ito,f gradient on contractile properties using mouse models of Irx5 knockout (Irx5-KO) for selective Ito,f elevation in the endomyocardium (ENDO) of the left ventricle (LV) and Kcnd2 ablation (KV4.2-KO) for selective Ito,freduction in the EPI. Irx5-KO mice exhibited decreased global LV contractility in association with reductions in cell shortening and Ca2+ transient amplitudes in isolated ENDO but not EPI cardiomyocytes. Moreover, transcriptional profiling revealed that the primary effect of Irx5 ablation on ECC-related genes was to increase Ito,f gene expression (i.e. Kcnd2 and Kcnip2) in the ENDO, but not the EPI. Indeed, KV4.2-KO mice showed selective increases in cell shortening and Ca2+ transients in isolated EPI cardiomyocytes, leading to enhanced ventricular contractility and mice lacking both Irx5 and Kcnd2 displayed elevated ventricular contractility comparable to KV4.2-KO mice. Our findings demonstrate that the transmural electromechanical heterogeneities in the healthy ventricles depend on the Irx5-dependent Ito,f gradients. These observations provide a useful framework for assessing the molecular mechanisms underlying the alterations in contractile heterogeneity seen in the diseased heart.
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Affiliation(s)
- Kyoung-Han Kim
- University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Yena Oh
- University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Jie Liu
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Biology, Faculty of Science, York University, Toronto, ON, Canada
| | - Saif Dababneh
- University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Ying Xia
- University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ri Youn Kim
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Dae-Kyum Kim
- University of Ottawa Heart Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Kiwon Ban
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Mansoor Husain
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Chi-Chung Hui
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Peter H Backx
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Biology, Faculty of Science, York University, Toronto, ON, Canada.,Toronto General Research Institute, University Health Network, Toronto, ON, Canada
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18
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Murphy JG, Gutzmann JJ, Lin L, Hu J, Petralia RS, Wang YX, Hoffman DA. R-type voltage-gated Ca 2+ channels mediate A-type K + current regulation of synaptic input in hippocampal dendrites. Cell Rep 2022; 38:110264. [PMID: 35045307 PMCID: PMC10496648 DOI: 10.1016/j.celrep.2021.110264] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 01/22/2023] Open
Abstract
The subthreshold voltage-gated transient K+ current (IA) carried by pore-forming Kv4.2 subunits regulates the propagation of synaptic input, dendritic excitability, and synaptic plasticity in CA1 pyramidal neuron dendrites of the hippocampus. We report that the Ca2+ channel subunit Cav2.3 regulates IA in this cell type. We initially identified Cav2.3 as a Kv4.2-interacting protein in a proteomic screen and we confirmed Cav2.3-Kv4.2 complex association using multiple techniques. Functionally, Cav2.3 Ca2+-entry increases Kv4.2-mediated whole-cell current due to an increase in Kv4.2 surface expression. Using pharmacology and Cav2.3 knockout mice, we show that Cav2.3 regulates the dendritic gradient of IA. Furthermore, the loss of Cav2.3 function leads to the enhancement of AMPA receptor-mediated synaptic currents and NMDA receptor-mediated spine Ca2+ influx. These results propose that Cav2.3 and Kv4.2 are integral constituents of an ion channel complex that affects synaptic function in the hippocampus.
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Affiliation(s)
- Jonathan G Murphy
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jakob J Gutzmann
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lin Lin
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiahua Hu
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dax A Hoffman
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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Liu X, Kumar V, Tsai NP, Auerbach BD. Hyperexcitability and Homeostasis in Fragile X Syndrome. Front Mol Neurosci 2022; 14:805929. [PMID: 35069112 PMCID: PMC8770333 DOI: 10.3389/fnmol.2021.805929] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/14/2021] [Indexed: 01/13/2023] Open
Abstract
Fragile X Syndrome (FXS) is a leading inherited cause of autism and intellectual disability, resulting from a mutation in the FMR1 gene and subsequent loss of its protein product FMRP. Despite this simple genetic origin, FXS is a phenotypically complex disorder with a range of physical and neurocognitive disruptions. While numerous molecular and cellular pathways are affected by FMRP loss, there is growing evidence that circuit hyperexcitability may be a common convergence point that can account for many of the wide-ranging phenotypes seen in FXS. The mechanisms for hyperexcitability in FXS include alterations to excitatory synaptic function and connectivity, reduced inhibitory neuron activity, as well as changes to ion channel expression and conductance. However, understanding the impact of FMR1 mutation on circuit function is complicated by the inherent plasticity in neural circuits, which display an array of homeostatic mechanisms to maintain activity near set levels. FMRP is also an important regulator of activity-dependent plasticity in the brain, meaning that dysregulated plasticity can be both a cause and consequence of hyperexcitable networks in FXS. This makes it difficult to separate the direct effects of FMR1 mutation from the myriad and pleiotropic compensatory changes associated with it, both of which are likely to contribute to FXS pathophysiology. Here we will: (1) review evidence for hyperexcitability and homeostatic plasticity phenotypes in FXS models, focusing on similarities/differences across brain regions, cell-types, and developmental time points; (2) examine how excitability and plasticity disruptions interact with each other to ultimately contribute to circuit dysfunction in FXS; and (3) discuss how these synaptic and circuit deficits contribute to disease-relevant behavioral phenotypes like epilepsy and sensory hypersensitivity. Through this discussion of where the current field stands, we aim to introduce perspectives moving forward in FXS research.
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Affiliation(s)
- Xiaopeng Liu
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Vipendra Kumar
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Nien-Pei Tsai
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Benjamin D. Auerbach
- Deparment of Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- *Correspondence: Benjamin D. Auerbach
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20
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Wang K, Xu F, Maylie J, Xu J. Anti-Müllerian Hormone Regulation of Synaptic Transmission in the Hippocampus Requires MAPK Signaling and Kv4.2 Potassium Channel Activity. Front Neurosci 2022; 15:772251. [PMID: 34975379 PMCID: PMC8716599 DOI: 10.3389/fnins.2021.772251] [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: 09/07/2021] [Accepted: 12/01/2021] [Indexed: 11/13/2022] Open
Abstract
Anti-Müllerian hormone (AMH) is a paracrine factor generated peripherally by the gonads to regulate gonadal function in adult mammals. We recently reported that AMH and AMH-specific receptor Anti-Müllerian hormone receptor 2 (AMHR2) are expressed in the hippocampus, and exogenous AMH protein rapidly increased synaptic transmission and long-term synaptic plasticity at the CA3-CA1 synapses. Here we examined the cell-specific expression of AMHR2 and the cellular mechanism of rapid boosting effect of AMH on synaptic transmission in mouse hippocampus. Immunofluorescence staining showed that AMHR2 was specifically expressed in the soma and dendrites of hippocampal pyramidal neurons, but not glial cells. Electrophysiological recordings on acute hippocampal slices showed that AMH did not affect AMPAR-mediated or N-Methyl-D-aspartic acid receptor (NMDAR)-mediated excitatory postsynaptic currents at the CA3-CA1 synapses. The small-conductance Ca2+-activated K+ channel (SK2) and A-type K+ channel (Kv4.2) contribute to shaping excitatory postsynaptic potentials (EPSPs) at the CA3-CA1 synapses. Bath application of apamin to block SK2 did not alter AMH effect on increasing EPSPs, whereas blocking Kv4.2 channel with 4-aminopyridine, or chelating internal Ca2+ with BAPTA occluded the action of AMH on boosting EPSPs. Kv4.2 activity is regulated by p38 mitogen-activated kinase (MAPK). Blocking p38 MAPK with SB203580 occluded the effect of AMH on increasing EPSPs. These results show that Kv4.2 channel contributes to the rapid action of AMH on boosting synaptic transmission in a Ca2+- and p38 MAPK-dependent manner. Our findings provide functional evidence that AMH enhances synaptic transmission through Kv4.2 channel in the hippocampus, suggesting a possible role of Kv4.2 channel in AMH-regulated neuronal process underlying learning and memory.
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Affiliation(s)
- Kang Wang
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Fuhua Xu
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - James Maylie
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Jing Xu
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, United States
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21
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Vallejos MJ, Eadaim A, Hahm ET, Tsunoda S. Age-related changes in Kv4/Shal and Kv1/Shaker expression in Drosophila and a role for reactive oxygen species. PLoS One 2021; 16:e0261087. [PMID: 34932577 PMCID: PMC8691634 DOI: 10.1371/journal.pone.0261087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/23/2021] [Indexed: 11/19/2022] Open
Abstract
Age-related changes in ion channel expression are likely to affect neuronal signaling. Here, we examine how age affects Kv4/Shal and Kv1/Shaker K+ channel protein levels in Drosophila. We show that Kv4/Shal protein levels decline sharply from 3 days to 10 days, then more gradually from 10 to 40 days after eclosion. In contrast, Kv1/Shaker protein exhibits a transient increase at 10 days that then stabilizes and eventually declines at 40 days. We present data that begin to show a relationship between reactive oxygen species (ROS), Kv4/Shal, and locomotor performance. We show that Kv4/Shal levels are negatively affected by ROS, and that over-expression of Catalase or RNAi knock-down of the ROS-generating enzyme, Nicotinamide Adenine Dinucleotide Phosphate (NADPH) Oxidase (NOX), can attenuate the loss of Kv4/Shal protein. Finally, we compare levels of Kv4.2 and Kv4.3 in the hippocampus, olfactory bulb, cerebellum, and motor cortex of mice aged 6 weeks and 1 year. While there was no global decline in Kv4.2/4.3 that parallels what we report in Drosophila, we did find that Kv4.2/4.3 are differentially affected in various brain regions; this survey of changes may help inform mammalian studies that examine neuronal function with age.
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Affiliation(s)
- Maximiliano J. Vallejos
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Abdunaser Eadaim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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22
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A general principle of dendritic constancy: A neuron's size- and shape-invariant excitability. Neuron 2021; 109:3647-3662.e7. [PMID: 34555313 DOI: 10.1016/j.neuron.2021.08.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 06/29/2021] [Accepted: 08/20/2021] [Indexed: 11/20/2022]
Abstract
Reducing neuronal size results in less membrane and therefore lower input conductance. Smaller neurons are thus more excitable, as seen in their responses to somatic current injections. However, the impact of a neuron's size and shape on its voltage responses to dendritic synaptic activation is much less understood. Here we use analytical cable theory to predict voltage responses to distributed synaptic inputs in unbranched cables, showing that these are entirely independent of dendritic length. For a given synaptic density, neuronal responses depend only on the average dendritic diameter and intrinsic conductivity. This remains valid for a wide range of morphologies irrespective of their arborization complexity. Spiking models indicate that morphology-invariant numbers of spikes approximate the percentage of active synapses. In contrast to spike rate, spike times do depend on dendrite morphology. In summary, neuronal excitability in response to distributed synaptic inputs is largely unaffected by dendrite length or complexity.
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23
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Clifton NE, Collado-Torres L, Burke EE, Pardiñas AF, Harwood JC, Di Florio A, Walters JTR, Owen MJ, O'Donovan MC, Weinberger DR, Holmans PA, Jaffe AE, Hall J. Developmental Profile of Psychiatric Risk Associated With Voltage-Gated Cation Channel Activity. Biol Psychiatry 2021; 90:399-408. [PMID: 33965196 PMCID: PMC8375582 DOI: 10.1016/j.biopsych.2021.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/26/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Recent breakthroughs in psychiatric genetics have implicated biological pathways onto which genetic risk for psychiatric disorders converges. However, these studies do not reveal the developmental time point(s) at which these pathways are relevant. METHODS We aimed to determine the relationship between psychiatric risk and developmental gene expression relating to discrete biological pathways. We used postmortem RNA sequencing data (BrainSeq and BrainSpan) from brain tissue at multiple prenatal and postnatal time points, with summary statistics from recent genome-wide association studies of schizophrenia, bipolar disorder, and major depressive disorder. We prioritized gene sets for overall enrichment of association with each disorder and then tested the relationship between the association of their constituent genes with their relative expression at each developmental stage. RESULTS We observed relationships between the expression of genes involved in voltage-gated cation channel activity during early midfetal, adolescence, and early adulthood time points and association with schizophrenia and bipolar disorder, such that genes more strongly associated with these disorders had relatively low expression during early midfetal development and higher expression during adolescence and early adulthood. The relationship with schizophrenia was strongest for the subset of genes related to calcium channel activity, while for bipolar disorder, the relationship was distributed between calcium and potassium channel activity genes. CONCLUSIONS Our results indicate periods during development when biological pathways related to the activity of calcium and potassium channels may be most vulnerable to the effects of genetic variants conferring risk for psychiatric disorders. Furthermore, they indicate key time points and potential targets for disorder-specific therapeutic interventions.
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Affiliation(s)
- Nicholas E Clifton
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom; MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom.
| | - Leonardo Collado-Torres
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, Maryland; Centre for Computational Biology, Johns Hopkins University Medical Campus, Baltimore, Maryland
| | - Emily E Burke
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, Maryland
| | - Antonio F Pardiñas
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Janet C Harwood
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Arianna Di Florio
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - James T R Walters
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Michael J Owen
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom; MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Michael C O'Donovan
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Daniel R Weinberger
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, Maryland; Departments of Psychiatry, Neurology, Neuroscience and Genetic Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Peter A Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Andrew E Jaffe
- Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, Maryland; Centre for Computational Biology, Johns Hopkins University Medical Campus, Baltimore, Maryland; Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom; MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
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24
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Lamothe SM, Kurata HT. Slc7a5 alters Kvβ-mediated regulation of Kv1.2. J Gen Physiol 2021; 152:151687. [PMID: 32311044 PMCID: PMC7335012 DOI: 10.1085/jgp.201912524] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/22/2020] [Accepted: 03/13/2020] [Indexed: 01/15/2023] Open
Abstract
The voltage-gated potassium channel Kv1.2 plays a pivotal role in neuronal excitability and is regulated by a variety of known and unknown extrinsic factors. The canonical accessory subunit of Kv1.2, Kvβ, promotes N-type inactivation and cell surface expression of the channel. We recently reported that a neutral amino acid transporter, Slc7a5, alters the function and expression of Kv1.2. In the current study, we investigated the effects of Slc7a5 on Kv1.2 in the presence of Kvβ1.2 subunits. We observed that Slc7a5-induced suppression of Kv1.2 current and protein expression was attenuated with cotransfection of Kvβ1.2. However, gating effects mediated by Slc7a5, including disinhibition and a hyperpolarizing shift in channel activation, were observed together with Kvβ-mediated inactivation, indicating convergent regulation of Kv1.2 by both regulatory proteins. Slc7a5 influenced several properties of Kvβ-induced inactivation of Kv1.2, including accelerated inactivation, a hyperpolarizing shift and greater extent of steady-state inactivation, and delayed recovery from inactivation. These modified inactivation properties were also apparent in altered deactivation of the Kv1.2/Kvβ/Slc7a5 channel complex. Taken together, these findings illustrate a functional interaction arising from simultaneous regulation of Kv1.2 by Kvβ and Slc7a5, leading to powerful effects on Kv1.2 expression, gating, and overall channel function.
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Affiliation(s)
- Shawn M Lamothe
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Harley T Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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25
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Oulé M, Atucha E, Wells TM, Macharadze T, Sauvage MM, Kreutz MR, Lopez-Rojas J. Dendritic Kv4.2 potassium channels selectively mediate spatial pattern separation in the dentate gyrus. iScience 2021; 24:102876. [PMID: 34386734 PMCID: PMC8346659 DOI: 10.1016/j.isci.2021.102876] [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: 02/12/2021] [Revised: 04/22/2021] [Accepted: 07/14/2021] [Indexed: 11/23/2022] Open
Abstract
The capacity to distinguish comparable experiences is fundamental for the recall of similar memories and has been proposed to require pattern separation in the dentate gyrus (DG). However, the cellular mechanisms by which mature granule cells (GCs) of the DG accomplish this function are poorly characterized. Here, we show that Kv4.2 channels selectively modulate the excitability of medial dendrites of dentate GCs. These dendrites are targeted by the medial entorhinal cortex, the main source of spatial inputs to the DG. Accordingly, we found that the spatial pattern separation capability of animals lacking the Kv4.2 channel is significantly impaired. This points to the role of intrinsic excitability in supporting the mnemonic function of the dentate and to the Kv4.2 channel as a candidate substrate promoting spatial pattern separation.
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Affiliation(s)
- Marie Oulé
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Erika Atucha
- Functional Architecture of Memory Department, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Tenyse M. Wells
- Functional Architecture of Memory Department, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Tamar Macharadze
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Department of Anesthesiology and Intensive Care Medicine, Otto-von-Guericke-University, 39120 Magdeburg, Germany
| | - Magdalena M. Sauvage
- Functional Architecture of Memory Department, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Otto von Guericke University, Medical Faculty, Functional Neuroplasticity Department, 39120, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
| | - Michael R. Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
- Leibniz Group 'Dendritic Organelles and Synaptic Function', University Medical Center Hamburg-Eppendorf, Center for Molecular Neurobiology (ZMNH), 20251 Hamburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany
| | - Jeffrey Lopez-Rojas
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), 39106 Magdeburg, Germany
- Department of Neuroscience, The Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10027, USA
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26
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Xiao F, Zhang X, Ni P, Yu H, Gao Q, Li M, Huo P, Wei Z, Wang S, Zhang Y, Zhao R, Li A, Li Z, Li Y, Cheng H, Du L, Ren S, Yu Q, Liu Y, Zhao Y. Voltage-dependent potassium channel Kv4.2 alleviates the ischemic stroke impairments through activating neurogenesis. Neurochem Int 2021; 150:105155. [PMID: 34384853 DOI: 10.1016/j.neuint.2021.105155] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/29/2021] [Accepted: 08/07/2021] [Indexed: 10/20/2022]
Abstract
As well as their ion transportation function, the voltage-dependent potassium channels could act as the cell signal inducer in a variety of pathogenic processes. However, their roles in neurogenesis after stroke insults have not been clearly illustrated. In our preliminary study, the expressions of voltage-dependent potassium channels Kv4.2 was significantly decreased after stroke in cortex, striatum and hippocampus by real-time quantitative PCR assay. To underlie the neuroprotection of Kv4.2 in stroke rehabilitation, recombinant plasmids encoding the cDNAs of mouse Kv4.2 was constructed. Behavioral tests showed that the increased Kv4.2 could be beneficial to the recovery of the sensory, the motor functions and the cognitive deficits after stroke. Temozolomide (TMZ), an inhibitor of neurogenesis, could partially abolish the mentioned protections of Kv4.2. The immunocytochemical staining showed that Kv4.2 could promote the proliferations of neural stem cells and induce the neural stem cells to differentiate into neurons in vitro and in vivo. And Kv4.2 could up-regulate the expressions of ERK1/2, p-ERK1/2, p-STAT3, NGF, p-TrkA, and BDNF, CAMKII and the concentration of intracellular Ca2+. Namely, we concluded that Kv4.2 promoted neurogenesis through ERK1/2/STAT3, NGF/TrkA, Ca2+/CAMKII signal pathways and rescued the ischemic impairments. Kv4.2 might be a potential drug target for ischemic stroke intervention.
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Affiliation(s)
- Fuyao Xiao
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Xiaojie Zhang
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Pinfei Ni
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Haibo Yu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, PR China
| | - Qiming Gao
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Mengyao Li
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Peiyun Huo
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Ziwei Wei
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Sihan Wang
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Yi Zhang
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Rui Zhao
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Aixue Li
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China; Department of Clinical Medicine, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Zhirui Li
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Yuejia Li
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Haixiao Cheng
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China
| | - Libo Du
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Suping Ren
- Beijing Institute of Transfusion Medicine, Beijing, 100850, PR China
| | - Qun Yu
- Beijing Institute of Transfusion Medicine, Beijing, 100850, PR China
| | - Yang Liu
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Yuming Zhao
- Department of Pharmacology, School of Basic Medical Science, Capital Medical University, Beijing, PR China.
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27
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Yang W, Zhou X, Zimmermann HR, Ma T. Brain-specific suppression of AMPKα2 isoform impairs cognition and hippocampal LTP by PERK-mediated eIF2α phosphorylation. Mol Psychiatry 2021; 26:1880-1897. [PMID: 32366952 PMCID: PMC8054310 DOI: 10.1038/s41380-020-0739-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 04/07/2020] [Accepted: 04/16/2020] [Indexed: 12/13/2022]
Abstract
The AMP-activated protein kinase (AMPK) is a molecular sensor to maintain energy homeostasis. The two isoforms of the AMPK catalytic subunit (AMPKα1 and α2) are both expressed in brains, but their roles in cognition are unknown. We generated conditional knockout mice in which brain AMPKα isoforms are selectively suppressed (AMPKα1/α2 cKO), and determined the isoform-specific effects in mice of either sex on cognition and synaptic plasticity. AMPKα2 cKO but not AMPKα1 cKO displayed impaired cognition and hippocampal late long-term potentiation (L-LTP). Further, AMPKα2 cKO mice exhibited decreased dendritic spine density and abnormal spine morphology in hippocampus. Electron microscope imaging demonstrated reduced postsynaptic density formation and fewer dendritic polyribosomes in hippocampi of AMPKα2 cKO mice. Biochemical studies revealed unexpected findings that repression of AMPKα2 resulted in increased phosphorylation of mRNA translational factor eIF2α and its kinase PERK. Importantly, L-LTP failure and cognitive impairments displayed in AMPKα2 cKO mice were alleviated by suppressing PERK activity pharmacologically or genetically. In summary, we demonstrate here that brain-specific suppression of AMPKα2 isoform impairs cognition and hippocampal LTP by PERK-mediated eIF2α phosphorylation, providing molecular mechanisms linking metabolism, protein synthesis, and cognition.
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Affiliation(s)
- Wenzhong Yang
- Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Xueyan Zhou
- Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Helena R. Zimmermann
- Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Tao Ma
- Department of Internal Medicine-Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA. .,Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA. .,Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
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28
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Eadaim A, Hahm ET, Justice ED, Tsunoda S. Cholinergic Synaptic Homeostasis Is Tuned by an NFAT-Mediated α7 nAChR-K v4/Shal Coupled Regulatory System. Cell Rep 2021; 32:108119. [PMID: 32905767 PMCID: PMC7521586 DOI: 10.1016/j.celrep.2020.108119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/23/2020] [Accepted: 08/17/2020] [Indexed: 11/26/2022] Open
Abstract
Homeostatic synaptic plasticity (HSP) involves compensatory mechanisms employed by neurons and circuits to preserve signaling when confronted with global changes in activity that may occur during physiological and pathological conditions. Cholinergic neurons, which are especially affected in some pathologies, have recently been shown to exhibit HSP mediated by nicotinic acetylcholine receptors (nAChRs). In Drosophila central neurons, pharmacological blockade of activity induces a homeostatic response mediated by the Drosophila α7 (Dα7) nAChR, which is tuned by a subsequent increase in expression of the voltage-dependent Kv4/Shal channel. Here, we show that an in vivo reduction of cholinergic signaling induces HSP mediated by Dα7 nAChRs, and this upregulation of Dα7 itself is sufficient to trigger transcriptional activation, mediated by nuclear factor of activated T cells (NFAT), of the Kv4/Shal gene, revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons. Eadaim et al. show that in vivo reduction of cholinergic signaling in Drosophila neurons induces synaptic homeostasis mediated by Dα7 nAChRs. This upregulation of Dα7 induces Kv4/Shal gene expression mediated by nuclear factor of activated T cells (NFAT), revealing a receptor-ion channel system coupled for homeostatic tuning in cholinergic neurons.
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Affiliation(s)
- Abdunaser Eadaim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Eu-Teum Hahm
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Elizabeth D Justice
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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29
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Cheng P, Qiu Z, Du Y. Potassium channels and autism spectrum disorder: An overview. Int J Dev Neurosci 2021; 81:479-491. [PMID: 34008235 DOI: 10.1002/jdn.10123] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/08/2021] [Accepted: 05/11/2021] [Indexed: 11/07/2022] Open
Abstract
Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders characterized by impaired social interaction and communication, and restricted, repetitive patterns of behaviors, interests, or activities. It had been demonstrated that potassium channels played a key role in regulating neuronal excitability, which was closely associated with neurological diseases including epilepsy, ataxia, myoclonus, and psychiatric disorders. In recent years, a growing body of evidence from whole-genome sequencing and whole-exome sequencing had identified several ASD susceptibility genes of potassium channels in ASD subjects. Genetically dysfunction of potassium channels may be involved in altered neuronal excitability and abnormal brain function in the pathogenesis of ASD. This review summarizes current findings on the features of ASD-risk genes (KCND2, KCNQ2, KCNQ3, KCNH5, KCNJ2, KCNJ10, and KCNMA1) and further expatiate their potential role in the pathogenicity of ASD.
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Affiliation(s)
- Peipei Cheng
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zilong Qiu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
| | - Yasong Du
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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30
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Hayman DJ, Modebadze T, Charlton S, Cheung K, Soul J, Lin H, Hao Y, Miles CG, Tsompani D, Jackson RM, Briggs MD, Piróg KA, Clark IM, Barter MJ, Clowry GJ, LeBeau FEN, Young DA. Increased hippocampal excitability in miR-324-null mice. Sci Rep 2021; 11:10452. [PMID: 34001919 PMCID: PMC8129095 DOI: 10.1038/s41598-021-89874-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 04/30/2021] [Indexed: 12/31/2022] Open
Abstract
MicroRNAs are non-coding RNAs that act to downregulate the expression of target genes by translational repression and degradation of messenger RNA molecules. Individual microRNAs have the ability to specifically target a wide array of gene transcripts, therefore allowing each microRNA to play key roles in multiple biological pathways. miR-324 is a microRNA predicted to target thousands of RNA transcripts and is expressed far more highly in the brain than in any other tissue, suggesting that it may play a role in one or multiple neurological pathways. Here we present data from the first global miR-324-null mice, in which increased excitability and interictal discharges were identified in vitro in the hippocampus. RNA sequencing was used to identify differentially expressed genes in miR-324-null mice which may contribute to this increased hippocampal excitability, and 3'UTR luciferase assays and western blotting revealed that two of these, Suox and Cd300lf, are novel direct targets of miR-324. Characterisation of microRNAs that produce an effect on neurological activity, such as miR-324, and identification of the pathways they regulate will allow a better understanding of the processes involved in normal neurological function and in turn may present novel pharmaceutical targets in treating neurological disease.
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Affiliation(s)
- Dan J Hayman
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Tamara Modebadze
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Sarah Charlton
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Kat Cheung
- Bioinformatics Support Unit, Faculty of Medical Sciences, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Jamie Soul
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Hua Lin
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Yao Hao
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
- Orthopedics Department, First Hospital of Shanxi Medical University, Yingze District, Taiyuan, 030000, China
| | - Colin G Miles
- Translational and Clinical Research Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Dimitra Tsompani
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Robert M Jackson
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Michael D Briggs
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Katarzyna A Piróg
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Ian M Clark
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Matt J Barter
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Gavin J Clowry
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - Fiona E N LeBeau
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
| | - David A Young
- Biosciences Institute, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK.
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31
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Johnston J. Pharmacology of A-Type K + Channels. Handb Exp Pharmacol 2021; 267:167-183. [PMID: 33907894 DOI: 10.1007/164_2021_456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Transient outward potassium currents were first described nearly 60 years ago, since then major strides have been made in understanding their molecular basis and physiological roles. From the large family of voltage-gated potassium channels members of 3 subfamilies can produce such fast-inactivating A-type potassium currents. Each subfamily gives rise to currents with distinct biophysical properties and pharmacological profiles and a simple workflow is provided to aid the identification of channels mediating A-type currents in native cells. Their unique properties and regulation enable A-type K+ channels to perform varied roles in excitable cells including repolarisation of the cardiac action potential, controlling spike and synaptic timing, regulating dendritic integration and long-term potentiation as well as being a locus of neural plasticity.
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Affiliation(s)
- Jamie Johnston
- Faculty of Biological Sciences, University of Leeds, Leeds, UK.
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32
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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33
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Kim KR, Kim Y, Jeong HJ, Kang JS, Lee SH, Kim Y, Lee SH, Ho WK. Impaired pattern separation in Tg2576 mice is associated with hyperexcitable dentate gyrus caused by Kv4.1 downregulation. Mol Brain 2021; 14:62. [PMID: 33785038 PMCID: PMC8011083 DOI: 10.1186/s13041-021-00774-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/23/2021] [Indexed: 12/05/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that causes memory loss. Most AD researches have focused on neurodegeneration mechanisms. Considering that neurodegenerative changes are not reversible, understanding early functional changes before neurodegeneration is critical to develop new strategies for early detection and treatment of AD. We found that Tg2576 mice exhibited impaired pattern separation at the early preclinical stage. Based on previous studies suggesting a critical role of dentate gyrus (DG) in pattern separation, we investigated functional changes in DG of Tg2576 mice. We found that granule cells in DG (DG-GCs) in Tg2576 mice showed increased action potential firing in response to long depolarizations and reduced 4-AP sensitive K+-currents compared to DG-GCs in wild-type (WT) mice. Among Kv4 family channels, Kv4.1 mRNA expression in DG was significantly lower in Tg2576 mice. We confirmed that Kv4.1 protein expression was reduced in Tg2576, and this reduction was restored by antioxidant treatment. Hyperexcitable DG and impaired pattern separation in Tg2576 mice were also recovered by antioxidant treatment. These results highlight the hyperexcitability of DG-GCs as a pathophysiologic mechanism underlying early cognitive deficits in AD and Kv4.1 as a new target for AD pathogenesis in relation to increased oxidative stress.
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Affiliation(s)
- Kyung-Ran Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Yoonsub Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Hyeon-Ju Jeong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Sang Hun Lee
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Yujin Kim
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Suk-Ho Lee
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Korea
| | - Won-Kyung Ho
- Department of Physiology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Korea.
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea.
- Department of Brain and Cognitive Science, Seoul National University College of Natural Science, Seoul, Korea.
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34
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Hegemann RU, Abraham WC. Postsynaptic cell firing triggers bidirectional metaplasticity depending on the LTP induction protocol. J Neurophysiol 2021; 125:1624-1635. [PMID: 33760659 DOI: 10.1152/jn.00514.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cell firing has been reported to variably upregulate or downregulate subsequently induced long-term potentiation (LTP). The aim of this study was to elucidate the parameters critical to driving each direction of the metaplasticity effect. The main focus was on the commonly used θ-burst stimulation (TBS) and high-frequency stimulation (HFS) protocols that are known to trigger distinct intracellular signaling cascades. To study action potential (AP)-induced metaplasticity, we used intracellular recordings from CA1 pyramidal cells of rat hippocampal slices. Somatic current injections were used to induce θ-burst firing (TBF) or high-frequency firing (HFF) for priming purposes, whereas LTP was induced 15 min later via TBS of Schaffer collaterals in stratum radiatum. TBS-LTP was inhibited by both priming protocols. Conversely, HFS-LTP was facilitated by HFF priming but not affected by TBF priming. Interestingly, both priming protocols reduced AP firing during TBS-LTP induction, and this effect correlated with the reduction of TBS-LTP. However, LTP was not rescued by restoring AP firing with somatic current injections during the TBS. Analysis of intrinsic properties revealed few changes, apart from a priming-induced increase in the medium afterhyperpolarization (HFF priming) and a decrease in the EPSP amplitude/slope ratio (TBF priming), which could in principle contribute to the inhibition of TBS-LTP by reducing depolarization and associated Ca2+ influx following synaptic activity or AP backpropagation. Overall, these data indicate that the more physiological TBS protocol for inducing LTP is particularly susceptible to homeostatic feedback inhibition by prior bouts of postsynaptic cell firing.NEW & NOTEWORTHY The induction of LTP in the hippocampus was bidirectionally regulated by prior postsynaptic cell firing, with θ-burst stimulation-induced LTP being consistently impaired by prior spiking, whereas high-frequency stimulation-induced LTP was either not changed or facilitated. Reductions in cell firing during LTP induction did not explain the LTP impairment. Overall, different patterns of postsynaptic firing induce distinct intracellular changes that can increase or decrease LTP depending on the induction protocol.
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Affiliation(s)
- Regina U Hegemann
- Department of Psychology, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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35
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Pacheco-Rojas DO, Delgado-Ramírez M, Villatoro-Gómez K, Moreno-Galindo EG, Rodríguez-Menchaca AA, Sánchez-Chapula JA, Ferrer T. Riluzole inhibits Kv4.2 channels acting on the closed and closed inactivated states. Eur J Pharmacol 2021; 899:174026. [PMID: 33722592 DOI: 10.1016/j.ejphar.2021.174026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 03/02/2021] [Accepted: 03/09/2021] [Indexed: 11/18/2022]
Abstract
Riluzole is an anticonvulsant drug also used to treat the amyotrophic lateral sclerosis and major depressive disorder. This compound has antiglutamatergic activity and is an important multichannel blocker. However, little is known about its actions on the Kv4.2 channels, the molecular correlate of the A-type K+ current (IA) and the fast transient outward current (Itof). Here, we investigated the effects of riluzole on Kv4.2 channels transiently expressed in HEK-293 cells. Riluzole inhibited Kv4.2 channels with an IC50 of 190 ± 14 μM and the effect was voltage- and frequency-independent. The activation rate of the current (at +50 mV) was not affected by the drug, nor the voltage dependence of channel activation, but the inactivation rate was accelerated by 100 and 300 μM riluzole. When Kv4.2 channels were maintained at the closed state, riluzole incubation induced a tonic current inhibition. In addition, riluzole significantly shifted the voltage dependence of inactivation to hyperpolarized potentials without affecting the recovery from inactivation. In the presence of the drug, the closed-state inactivation was significantly accelerated, and the percentage of inactivated channels was increased. Altogether, our findings indicate that riluzole inhibits Kv4.2 channels mainly affecting the closed and closed-inactivated states.
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Affiliation(s)
- David O Pacheco-Rojas
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Mayra Delgado-Ramírez
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Kathya Villatoro-Gómez
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza #2405, Col. Los Filtros, San Luis Potosí, SLP, 78210, Mexico
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico.
| | - Tania Ferrer
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965 Col, Villas San Sebastián, Colima, COL, 28045, Mexico.
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36
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Tiwari D, Schaefer TL, Schroeder-Carter LM, Krzeski JC, Bunk AT, Parkins EV, Snider A, Danzer R, Williams MT, Vorhees CV, Danzer SC, Gross C. The potassium channel Kv4.2 regulates dendritic spine morphology, electroencephalographic characteristics and seizure susceptibility in mice. Exp Neurol 2020; 334:113437. [PMID: 32822706 PMCID: PMC7642025 DOI: 10.1016/j.expneurol.2020.113437] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 08/13/2020] [Accepted: 08/17/2020] [Indexed: 01/21/2023]
Abstract
The voltage-gated potassium channel Kv4.2 is a critical regulator of dendritic excitability in the hippocampus and is crucial for dendritic signal integration. Kv4.2 mRNA and protein expression as well as function are reduced in several genetic and pharmacologically induced rodent models of epilepsy and autism. It is not known, however, whether reduced Kv4.2 is just an epiphenomenon or a disease-contributing cause of neuronal hyperexcitability and behavioral impairments in these neurological disorders. To address this question, we used male and female mice heterozygous for a Kv.2 deletion and adult-onset manipulation of hippocampal Kv4.2 expression in male mice to assess the role of Kv4.2 in regulating neuronal network excitability, morphology and anxiety-related behaviors. We observed a reduction in dendritic spine density and reduced proportions of thin and stubby spines but no changes in anxiety, overall activity, or retention of conditioned freezing memory in Kv4.2 heterozygous mice compared with wildtype littermates. Using EEG analyses, we showed elevated theta power and increased spike frequency in Kv4.2 heterozygous mice under basal conditions. In addition, the latency to onset of kainic acid-induced seizures was significantly shortened in Kv4.2 heterozygous mice compared with wildtype littermates, which was accompanied by a significant increase in theta power. By contrast, overexpressing Kv4.2 in wildtype mice through intrahippocampal injection of Kv4.2-expressing lentivirus delayed seizure onset and reduced EEG power. These results suggest that Kv4.2 is an important regulator of neuronal network excitability and dendritic spine morphology, but not anxiety-related behaviors. In the future, manipulation of Kv4.2 expression could be used to alter seizure susceptibility in epilepsy.
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Affiliation(s)
- Durgesh Tiwari
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Tori L Schaefer
- Division of Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | | | - Joseph C Krzeski
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Alexander T Bunk
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Emma V Parkins
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Andrew Snider
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Reese Danzer
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Michael T Williams
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Charles V Vorhees
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Steve C Danzer
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Christina Gross
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
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37
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Alfaro-Ruíz R, Aguado C, Martín-Belmonte A, Moreno-Martínez AE, Luján R. Cellular and Subcellular Localisation of Kv4-Associated KChIP Proteins in the Rat Cerebellum. Int J Mol Sci 2020; 21:ijms21176403. [PMID: 32899153 PMCID: PMC7503578 DOI: 10.3390/ijms21176403] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 11/29/2022] Open
Abstract
The K+ channel interacting proteins (KChIPs) are a family of cytosolic proteins that interact with Kv4 channels, leading to higher current density, modulation of channel inactivation and faster recovery from inactivation. Using immunohistochemical techniques at the light and electron microscopic level combined with quantitative analysis, we investigated the cellular and subcellular localisation of KChIP3 and KChIP4 to compare their distribution patterns with those for Kv4.2 and Kv4.3 in the cerebellar cortex. Immunohistochemistry at the light microscopic level demonstrated that KChIP3, KChIP4, Kv4.2 and Kv4.3 proteins were widely expressed in the cerebellum, with mostly overlapping patterns. Immunoelectron microscopic techniques showed that KChIP3, KChIP4, Kv4.2 and Kv4.3 shared virtually the same somato-dendritic domains of Purkinje cells and granule cells. Application of quantitative approaches showed that KChIP3 and KChIP4 were mainly membrane-associated, but also present at cytoplasmic sites close to the plasma membrane, in dendritic spines and shafts of Purkinje cells (PCs) and dendrites of granule cells (GCs). Similarly, immunoparticles for Kv4.2 and Kv4.3 were observed along the plasma membrane and at intracellular sites in the same neuron populations. In addition to the preferential postsynaptic distribution, KChIPs and Kv4 were also distributed presynaptically in parallel fibres and mossy fibres. Immunoparticles for KChIP3, KChIP4 and Kv4.3 were detected in parallel fibres, and KChIP3, KChIP4, Kv4.2 and Kv4.3 were found in parallel fibres, indicating that composition of KChIP and Kv4 seems to be input-dependent. Together, our findings unravelled previously uncharacterised KChIP and Kv4 subcellular localisation patterns in neurons, revealed that KChIP have additional Kv4-unrelated functions in the cerebellum and support the formation of macromolecular complexes between KChIP3 and KChIP4 with heterotetrameric Kv4.2/Kv4.3 channels.
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Affiliation(s)
| | | | | | | | - Rafael Luján
- Correspondence: ; Tel.: +34-967-599200 (ext. 2196)
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38
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Hu JH, Malloy C, Hoffman DA. P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation. Int J Mol Sci 2020; 21:ijms21165921. [PMID: 32824677 PMCID: PMC7460594 DOI: 10.3390/ijms21165921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/06/2020] [Accepted: 08/14/2020] [Indexed: 01/23/2023] Open
Abstract
The subthreshold, transient A-type K+ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input-output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.
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39
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Hiratani N, Latham PE. Rapid Bayesian learning in the mammalian olfactory system. Nat Commun 2020; 11:3845. [PMID: 32737295 PMCID: PMC7395793 DOI: 10.1038/s41467-020-17490-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 07/02/2020] [Indexed: 01/17/2023] Open
Abstract
Many experimental studies suggest that animals can rapidly learn to identify odors and predict the rewards associated with them. However, the underlying plasticity mechanism remains elusive. In particular, it is not clear how olfactory circuits achieve rapid, data efficient learning with local synaptic plasticity. Here, we formulate olfactory learning as a Bayesian optimization process, then map the learning rules into a computational model of the mammalian olfactory circuit. The model is capable of odor identification from a small number of observations, while reproducing cellular plasticity commonly observed during development. We extend the framework to reward-based learning, and show that the circuit is able to rapidly learn odor-reward association with a plausible neural architecture. These results deepen our theoretical understanding of unsupervised learning in the mammalian brain. How can rodents make sense of the olfactory environment without supervision? Here, the authors formulate olfactory learning as an integrated Bayesian inference problem, then derive a set of synaptic plasticity rules and neural dynamics that enables near-optimal learning of odor identification.
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Affiliation(s)
- Naoki Hiratani
- Gatsby Computational Neuroscience Unit, University College London, 25 Howland Street, London, W1T 4JG, UK.
| | - Peter E Latham
- Gatsby Computational Neuroscience Unit, University College London, 25 Howland Street, London, W1T 4JG, UK
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40
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Aceto G, Re A, Mattera A, Leone L, Colussi C, Rinaudo M, Scala F, Gironi K, Barbati SA, Fusco S, Green T, Laezza F, D'Ascenzo M, Grassi C. GSK3β Modulates Timing-Dependent Long-Term Depression Through Direct Phosphorylation of Kv4.2 Channels. Cereb Cortex 2020; 29:1851-1865. [PMID: 29790931 DOI: 10.1093/cercor/bhy042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/15/2018] [Accepted: 02/07/2018] [Indexed: 12/31/2022] Open
Abstract
Spike timing-dependent plasticity (STDP) is a form of activity-dependent remodeling of synaptic strength that underlies memory formation. Despite its key role in dictating learning rules in the brain circuits, the molecular mechanisms mediating STDP are still poorly understood. Here, we show that spike timing-dependent long-term depression (tLTD) and A-type K+ currents are modulated by pharmacological agents affecting the levels of active glycogen-synthase kinase 3 (GSK3) and by GSK3β knockdown in layer 2/3 of the mouse somatosensory cortex. Moreover, the blockade of A-type K+ currents mimics the effects of GSK3 up-regulation on tLTD and occludes further changes in synaptic strength. Pharmacological, immunohistochemical and biochemical experiments revealed that GSK3β influence over tLTD induction is mediated by direct phosphorylation at Ser-616 of the Kv4.2 subunit, a molecular determinant of A-type K+ currents. Collectively, these results identify the functional interaction between GSK3β and Kv4.2 channel as a novel mechanism for tLTD modulation providing exciting insight into the understanding of GSK3β role in synaptic plasticity.
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Affiliation(s)
- Giuseppe Aceto
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Agnese Re
- Institute of Cell Biology and Neurobiology, National Research Council, Rome, Italy
| | - Andrea Mattera
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Lucia Leone
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A Gemelli, IRCCS, Rome, Italy
| | - Claudia Colussi
- Institute of Cell Biology and Neurobiology, National Research Council, Rome, Italy
| | - Marco Rinaudo
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Federico Scala
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Katia Gironi
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy
| | | | - Salvatore Fusco
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A Gemelli, IRCCS, Rome, Italy
| | - Thomas Green
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Fernanda Laezza
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA
| | - Marcello D'Ascenzo
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A Gemelli, IRCCS, Rome, Italy
| | - Claudio Grassi
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A Gemelli, IRCCS, Rome, Italy
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41
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Kessi M, Chen B, Peng J, Tang Y, Olatoutou E, He F, Yang L, Yin F. Intellectual Disability and Potassium Channelopathies: A Systematic Review. Front Genet 2020; 11:614. [PMID: 32655623 PMCID: PMC7324798 DOI: 10.3389/fgene.2020.00614] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/20/2020] [Indexed: 01/15/2023] Open
Abstract
Intellectual disability (ID) manifests prior to adulthood as severe limitations to intellectual function and adaptive behavior. The role of potassium channelopathies in ID is poorly understood. Therefore, we aimed to evaluate the relationship between ID and potassium channelopathies. We hypothesized that potassium channelopathies are strongly associated with ID initiation, and that both gain- and loss-of-function mutations lead to ID. This systematic review explores the burden of potassium channelopathies, possible mechanisms, advancements using animal models, therapies, and existing gaps. The literature search encompassed both PubMed and Embase up to October 2019. A total of 75 articles describing 338 cases were included in this review. Nineteen channelopathies were identified, affecting the following genes: KCNMA1, KCNN3, KCNT1, KCNT2, KCNJ10, KCNJ6, KCNJ11, KCNA2, KCNA4, KCND3, KCNH1, KCNQ2, KCNAB1, KCNQ3, KCNQ5, KCNC1, KCNB1, KCNC3, and KCTD3. Twelve of these genes presented both gain- and loss-of-function properties, three displayed gain-of-function only, three exhibited loss-of-function only, and one had unknown function. How gain- and loss-of-function mutations can both lead to ID remains largely unknown. We identified only a few animal studies that focused on the mechanisms of ID in relation to potassium channelopathies and some of the few available therapeutic options (channel openers or blockers) appear to offer limited efficacy. In conclusion, potassium channelopathies contribute to the initiation of ID in several instances and this review provides a comprehensive overview of which molecular players are involved in some of the most prominent disease phenotypes.
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Affiliation(s)
- Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China.,Kilimanjaro Christian Medical University College, Moshi, Tanzania.,Mawenzi Regional Referral Hospital, Moshi, Tanzania
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Yulin Tang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Eleonore Olatoutou
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Lifen Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
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42
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Ohtsuki G, Shishikura M, Ozaki A. Synergistic excitability plasticity in cerebellar functioning. FEBS J 2020; 287:4557-4593. [PMID: 32367676 DOI: 10.1111/febs.15355] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 04/22/2020] [Accepted: 04/30/2020] [Indexed: 12/27/2022]
Abstract
The cerebellum, a universal processor for sensory acquisition and internal models, and its association with synaptic and nonsynaptic plasticity have been envisioned as the biological correlates of learning, perception, and even thought. Indeed, the cerebellum is no longer considered merely as the locus of motor coordination and its learning. Here, we introduce the mechanisms underlying the induction of multiple types of plasticity in cerebellar circuit and give an overview focusing on the plasticity of nonsynaptic intrinsic excitability. The discovery of long-term potentiation of synaptic responsiveness in hippocampal neurons led investigations into changes of their intrinsic excitability. This activity-dependent potentiation of neuronal excitability is distinct from that of synaptic efficacy. Systematic examination of excitability plasticity has indicated that the modulation of various types of Ca2+ - and voltage-dependent K+ channels underlies the phenomenon, which is also triggered by immune activity. Intrinsic plasticity is expressed specifically on dendrites and modifies the integrative processing and filtering effect. In Purkinje cells, modulation of the discordance of synaptic current on soma and dendrite suggested a novel type of cellular learning mechanism. This property enables a plausible synergy between synaptic efficacy and intrinsic excitability, by amplifying electrical conductivity and influencing the polarity of bidirectional synaptic plasticity. Furthermore, the induction of intrinsic plasticity in the cerebellum correlates with motor performance and cognitive processes, through functional connections from the cerebellar nuclei to neocortex and associated regions: for example, thalamus and midbrain. Taken together, recent advances in neuroscience have begun to shed light on the complex functioning of nonsynaptic excitability and the synergy.
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Affiliation(s)
- Gen Ohtsuki
- The Hakubi Center for Advanced Research, Kyoto University, Japan.,Department of Biophysics, Kyoto University Graduate School of Science, Japan.,Department of Drug Discovery Medicine, Kyoto University Graduate School of Medicine, Japan
| | - Mari Shishikura
- Department of Biophysics, Kyoto University Graduate School of Science, Japan
| | - Akitoshi Ozaki
- Department of Biophysics, Kyoto University Graduate School of Science, Japan
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Grandi FC, De Tomasi L, Mustapha M. Single-Cell RNA Analysis of Type I Spiral Ganglion Neurons Reveals a Lmx1a Population in the Cochlea. Front Mol Neurosci 2020; 13:83. [PMID: 32523514 PMCID: PMC7261882 DOI: 10.3389/fnmol.2020.00083] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
In the mature cochlea, each inner hair cell (IHC) is innervated by multiple spiral ganglion neurons of type I (SGNI). SGNIs are morphologically and electro-physiologically diverse. Also, they differ in their susceptibility to noise insult. However, the molecular underpinnings of their identity and physiological differences remain poorly understood. In this study, we developed a novel triple transgenic mouse, which enabled the isolation of pure populations of SGNIs and the analysis of a 96-gene panel via single-cell qPCR. We found three distinct populations of Type I SGNs, which were marked by their exclusive expression of Lmx1a, Slc4a4, or Mfap4/Fzd2, respectively, at postnatal days P3, P8, and P12. Our data suggest that afferent SGN subtypes are established genetically before the onset of hearing and that the expression of key physiological markers, such as ion channels, is heterogeneous and may be underlying the heterogeneous firing proprieties of SGNIs.
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Affiliation(s)
| | - Lara De Tomasi
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Mirna Mustapha
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom.,Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
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Hu JH, Malloy C, Tabor GT, Gutzmann JJ, Liu Y, Abebe D, Karlsson RM, Durell S, Cameron HA, Hoffman DA. Activity-dependent isomerization of Kv4.2 by Pin1 regulates cognitive flexibility. Nat Commun 2020; 11:1567. [PMID: 32218435 PMCID: PMC7099064 DOI: 10.1038/s41467-020-15390-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 02/29/2020] [Indexed: 11/28/2022] Open
Abstract
Voltage-gated K+ channels function in macromolecular complexes with accessory subunits to regulate brain function. Here, we describe a peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1)-dependent mechanism that regulates the association of the A-type K+ channel subunit Kv4.2 with its auxiliary subunit dipeptidyl peptidase 6 (DPP6), and thereby modulates neuronal excitability and cognitive flexibility. We show that activity-induced Kv4.2 phosphorylation triggers Pin1 binding to, and isomerization of, Kv4.2 at the pThr607-Pro motif, leading to the dissociation of the Kv4.2-DPP6 complex. We generated a novel mouse line harboring a knock-in Thr607 to Ala (Kv4.2TA) mutation that abolished dynamic Pin1 binding to Kv4.2. CA1 pyramidal neurons of the hippocampus from these mice exhibited altered Kv4.2-DPP6 interaction, increased A-type K+ current, and reduced neuronal excitability. Behaviorally, Kv4.2TA mice displayed normal initial learning but improved reversal learning in both Morris water maze and lever press paradigms. These findings reveal a Pin1-mediated mechanism regulating reversal learning and provide potential targets for the treatment of neuropsychiatric disorders characterized by cognitive inflexibility.
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Affiliation(s)
- Jia-Hua Hu
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - Cole Malloy
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - G Travis Tabor
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
- Medical Scientist Training Program, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Jakob J Gutzmann
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - Ying Liu
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - Daniel Abebe
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA
| | - Rose-Marie Karlsson
- Section on Neuroplasticity, National Institute of Mental Health, Bethesda, MD, 20892, USA
| | - Stewart Durell
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, MD, 20892, USA
| | - Heather A Cameron
- Section on Neuroplasticity, National Institute of Mental Health, Bethesda, MD, 20892, USA
| | - Dax A Hoffman
- Section on Molecular Neurophysiology and Biophysics, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, 20892, USA.
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Chronic mild stress alters synaptic plasticity in the nucleus accumbens through GSK3β-dependent modulation of Kv4.2 channels. Proc Natl Acad Sci U S A 2020; 117:8143-8153. [PMID: 32209671 DOI: 10.1073/pnas.1917423117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although major depressive disorder (MDD) is highly prevalent, its pathophysiology is poorly understood. Recent evidence suggests that glycogen-synthase kinase 3β (GSK3β) plays a key role in memory formation, yet its role in mood regulation remains controversial. Here, we investigated whether GSK3β activity in the nucleus accumbens (NAc) is associated with depression-like behaviors and synaptic plasticity. We performed whole-cell patch-clamp recordings of medium spiny neurons (MSNs) in the NAc and determined the role of GSK3β in spike timing-dependent long-term potentiation (tLTP) in the chronic unpredictable mild stress (CUMS) mouse model of depression. To assess the specific role of GSK3β in tLTP, we used in vivo genetic silencing by an adeno-associated viral vector (AAV2) short hairpin RNA against GSK3β. In addition, we examined the role of the voltage-gated potassium Kv4.2 subunit, a molecular determinant of A-type K+ currents, as a potential downstream target of GSK3β. We found increased levels of active GSK3β and augmented tLTP in CUMS mice, a phenotype that was prevented by selective GSK3β knockdown. Furthermore, knockdown of GSK3β in the NAc ameliorated depressive-like behavior in CUMS mice. Electrophysiological, immunohistochemical, biochemical, and pharmacological experiments revealed that inhibition of the Kv4.2 channel through direct phosphorylation at Ser-616 mediated the GSK3β-dependent tLTP changes in CUMS mice. Our results identify GSK3β regulation of Kv4.2 channels as a molecular mechanism of MSN maladaptive plasticity underlying depression-like behaviors and suggest that the GSK3β-Kv4.2 axis may be an attractive therapeutic target for MDD.
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Kv4.1, a Key Ion Channel For Low Frequency Firing of Dentate Granule Cells, Is Crucial for Pattern Separation. J Neurosci 2020; 40:2200-2214. [PMID: 32047055 DOI: 10.1523/jneurosci.1541-19.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 12/30/2019] [Accepted: 01/23/2020] [Indexed: 11/21/2022] Open
Abstract
The dentate gyrus (DG) in the hippocampus may play key roles in remembering distinct episodes through pattern separation, which may be subserved by the sparse firing properties of granule cells (GCs) in the DG. Low intrinsic excitability is characteristic of mature GCs, but ion channel mechanisms are not fully understood. Here, we investigated ionic channel mechanisms for firing frequency regulation in hippocampal GCs using male and female mice, and identified Kv4.1 as a key player. Immunofluorescence analysis showed that Kv4.1 was preferentially expressed in the DG, and its expression level determined by Western blot analysis was higher at 8-week than 3-week-old mice, suggesting a developmental regulation of Kv4.1 expression. With respect to firing frequency, GCs are categorized into two distinctive groups: low-frequency (LF) and high-frequency (HF) firing GCs. Input resistance (R in) of most LF-GCs is lower than 200 MΩ, suggesting that LF-GCs are fully mature GCs. Kv4.1 channel inhibition by intracellular perfusion of Kv4.1 antibody increased firing rates and gain of the input-output relationship selectively in LF-GCs with no significant effect on resting membrane potential and R in, but had no effect in HF-GCs. Importantly, mature GCs from mice depleted of Kv4.1 transcripts in the DG showed increased firing frequency, and these mice showed an impairment in contextual discrimination task. Our findings suggest that Kv4.1 expression occurring at late stage of GC maturation is essential for low excitability of DG networks and thereby contributes to pattern separation.SIGNIFICANCE STATEMENT The sparse activity of dentate granule cells (GCs), which is essential for pattern separation, is supported by high inhibitory inputs and low intrinsic excitability of GCs. Low excitability of GCs is thought to be attributable to a high K+ conductance at resting membrane potentials, but this study identifies Kv4.1, a depolarization-activated K+ channel, as a key ion channel that regulates firing of GCs without affecting resting membrane potentials. Kv4.1 expression is developmentally regulated and Kv4.1 currents are detected only in mature GCs that show low-frequency firing, but not in less mature high-frequency firing GCs. Furthermore, mice depleted of Kv4.1 transcripts in the dentate gyrus show impaired pattern separation, suggesting that Kv4.1 is crucial for sparse coding and pattern separation.
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Jain A, Narayanan R. Degeneracy in the emergence of spike-triggered average of hippocampal pyramidal neurons. Sci Rep 2020; 10:374. [PMID: 31941985 PMCID: PMC6962224 DOI: 10.1038/s41598-019-57243-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 12/26/2019] [Indexed: 12/15/2022] Open
Abstract
Hippocampal pyramidal neurons are endowed with signature excitability characteristics, exhibit theta-frequency selectivity - manifesting as impedance resonance and as a band-pass structure in the spike-triggered average (STA) - and coincidence detection tuned for gamma-frequency inputs. Are there specific constraints on molecular-scale (ion channel) properties in the concomitant emergence of cellular-scale encoding (feature detection and selectivity) and excitability characteristics? Here, we employed a biophysically-constrained unbiased stochastic search strategy involving thousands of conductance-based models, spanning 11 active ion channels, to assess the concomitant emergence of 14 different electrophysiological measurements. Despite the strong biophysical and physiological constraints, we found models that were similar in terms of their spectral selectivity, operating mode along the integrator-coincidence detection continuum and intrinsic excitability characteristics. The parametric combinations that resulted in these functionally similar models were non-unique with weak pair-wise correlations. Employing virtual knockout of individual ion channels in these functionally similar models, we found a many-to-many relationship between channels and physiological characteristics to mediate this degeneracy, and predicted a dominant role for HCN and transient potassium channels in regulating hippocampal neuronal STA. Our analyses reveals the expression of degeneracy, that results from synergistic interactions among disparate channel components, in the concomitant emergence of neuronal excitability and encoding characteristics.
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Affiliation(s)
- Abha Jain
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.,Undergraduate program, Indian Institute of Science, Bangalore, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
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48
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Mishra P, Narayanan R. Heterogeneities in intrinsic excitability and frequency-dependent response properties of granule cells across the blades of the rat dentate gyrus. J Neurophysiol 2020; 123:755-772. [PMID: 31913748 PMCID: PMC7052640 DOI: 10.1152/jn.00443.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The dentate gyrus (DG), the input gate to the hippocampus proper, is anatomically segregated into three different sectors, namely, the suprapyramidal blade, the crest region, and the infrapyramidal blade. Although there are well-established differences between these sectors in terms of neuronal morphology, connectivity patterns, and activity levels, differences in electrophysiological properties of granule cells within these sectors have remained unexplored. Here, employing somatic whole cell patch-clamp recordings from the rat DG, we demonstrate that granule cells in these sectors manifest considerable heterogeneities in their intrinsic excitability, temporal summation, action potential characteristics, and frequency-dependent response properties. Across sectors, these neurons showed positive temporal summation of their responses to inputs mimicking excitatory postsynaptic currents and showed little to no sag in their voltage responses to pulse currents. Consistently, the impedance amplitude profile manifested low-pass characteristics and the impedance phase profile lacked positive phase values at all measured frequencies and voltages and for all sectors. Granule cells in all sectors exhibited class I excitability, with broadly linear firing rate profiles, and granule cells in the crest region fired significantly fewer action potentials compared with those in the infrapyramidal blade. Finally, we found weak pairwise correlations across the 18 different measurements obtained individually from each of the three sectors, providing evidence that these measurements are indeed reporting distinct aspects of neuronal physiology. Together, our analyses show that granule cells act as integrators of afferent information and emphasize the need to account for the considerable physiological heterogeneities in assessing their roles in information encoding and processing.NEW & NOTEWORTHY We employed whole cell patch-clamp recordings from granule cells in the three subregions of the rat dentate gyrus to demonstrate considerable heterogeneities in their intrinsic excitability, temporal summation, action potential characteristics, and frequency-dependent response properties. Across sectors, granule cells did not express membrane potential resonance, and their impedance profiles lacked inductive phase leads at all measured frequencies. Our analyses also show that granule cells manifest class I excitability characteristics, categorizing them as integrators of afferent information.
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Affiliation(s)
- Poonam Mishra
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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Basak R, Narayanan R. Robust emergence of sharply tuned place-cell responses in hippocampal neurons with structural and biophysical heterogeneities. Brain Struct Funct 2020; 225:567-590. [PMID: 31900587 DOI: 10.1007/s00429-019-02018-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 12/17/2019] [Indexed: 01/06/2023]
Abstract
Hippocampal pyramidal neurons sustain propagation of fast electrical signals and are electrotonically non-compact structures exhibiting cell-to-cell variability in their complex dendritic arborization. In this study, we demonstrate that sharp place-field tuning and several somatodendritic functional maps concomitantly emerge despite the presence of geometrical heterogeneities in these neurons. We establish this employing an unbiased stochastic search strategy involving thousands of models that spanned several morphologies and distinct profiles of dispersed synaptic localization and channel expression. Mechanistically, employing virtual knockout models (VKMs), we explored the impact of bidirectional modulation in dendritic spike prevalence on place-field tuning sharpness. Consistent with the prior literature, we found that across all morphologies, virtual knockout of either dendritic fast sodium channels or N-methyl-D-aspartate receptors led to a reduction in dendritic spike prevalence, whereas A-type potassium channel knockouts resulted in a non-specific increase in dendritic spike prevalence. However, place-field tuning sharpness was critically impaired in all three sets of VKMs, demonstrating that sharpness in feature tuning is maintained by an intricate balance between mechanisms that promote and those that prevent dendritic spike initiation. From the functional standpoint of the emergence of sharp feature tuning and intrinsic functional maps, within this framework, geometric variability was compensated by a combination of synaptic democracy, the ability of randomly dispersed synapses to yield sharp tuning through dendritic spike initiation, and ion-channel degeneracy. Our results suggest electrotonically non-compact neurons to be endowed with several degrees of freedom, encompassing channel expression, synaptic localization and morphological microstructure, in achieving sharp feature encoding and excitability homeostasis.
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Affiliation(s)
- Reshma Basak
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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50
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Siddiqui S, Khan F, Jamali KS, Musharraf SG. Madecassic Acid Reduces Fast Transient Potassium Channels and Promotes Neurite Elongation in Hippocampal CA1 Neurons. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2019; 19:12-26. [PMID: 31713492 DOI: 10.2174/1871527318666191111105508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVE Madecassic Acid (MA) is well known to induce neurite elongation. However, its correlation with the expression of fast transient potassium (AKv) channels during neuronal development has not been well studied. Therefore, the present study was designed to investigate the effects of MA on the modulation of AKv channels during neurite outgrowth. METHODS Neurite outgrowth was measured with morphometry software, and Kv4 currents were recorded by using the patch clamp technique. RESULTS The ability of MA to promote neurite outgrowth is dose-dependent and was blocked by using the mitogen/extracellular signal-regulated kinase (MEK) inhibitor U0126. MA reduced the peak current density and surface expression of the AKv channel Kv4.2 with or without the presence of NaN3. The surface expression of Kv4.2 channels was also reduced after MA treatment of growing neurons. Ethylene glycol tetraacetic acid (EGTA) and an N-methyl-D-aspartate (NMDA) receptor blocker, MK801 along with MA prevented the effect of MA on neurite length, indicating that calcium entry through NMDA receptors is necessary for MA-induced neurite outgrowth. CONCLUSION The data demonstrated that MA increased neurite outgrowth by internalizing AKv channels in neurons. Any alterations in the precise density of ion channels can lead to deleterious consequences on health because it changes the electrical and mechanical function of a neuron or a cell. Modulating ion channel's density is exciting research in order to develop novel drugs for the therapeutic treatment of various diseases of CNS.
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Affiliation(s)
- Sonia Siddiqui
- Department of Biochemistry, Dow University of Health Sciences (DUHS), Karachi, Pakistan.,Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences (ICCBS), University of Karachi 75270, Pakistan
| | - Faisal Khan
- Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences (ICCBS), University of Karachi 75270, Pakistan
| | - Khawar Saeed Jamali
- Department of Surgery, Dow University of Health Sciences (DUHS), Karachi, Pakistan
| | - Syed Ghulam Musharraf
- HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi 75270, Pakistan
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