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Fan WY, Chen YM, Wang YF, Wang YQ, Hu JQ, Tang WX, Feng Y, Cheng Q, Xue L. L-Type Calcium Channel Modulates Low-Intensity Pulsed Ultrasound-Induced Excitation in Cultured Hippocampal Neurons. Neurosci Bull 2024; 40:921-936. [PMID: 38498092 PMCID: PMC11250733 DOI: 10.1007/s12264-024-01186-2] [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: 07/06/2023] [Accepted: 12/06/2023] [Indexed: 03/19/2024] Open
Abstract
As a noninvasive technique, ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo. The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and further impact the electrophysiological properties of targeted neurons. However, the underlying mechanism of low-intensity pulsed ultrasound (LIPUS)-induced neuro-modulation effects is still unclear. Here, we characterize the excitatory effects of LIPUS on spontaneous activity and the intracellular Ca2+ homeostasis in cultured hippocampal neurons. By whole-cell patch clamp recording, we found that 15 min of 1-MHz LIPUS boosts the frequency of both spontaneous action potentials and spontaneous excitatory synaptic currents (sEPSCs) and also increases the amplitude of sEPSCs in hippocampal neurons. This phenomenon lasts for > 10 min after LIPUS exposure. Together with Ca2+ imaging, we clarified that LIPUS increases the [Ca2+]cyto level by facilitating L-type Ca2+ channels (LTCCs). In addition, due to the [Ca2+]cyto elevation by LIPUS exposure, the Ca2+-dependent CaMKII-CREB pathway can be activated within 30 min to further regulate the gene transcription and protein expression. Our work suggests that LIPUS regulates neuronal activity in a Ca2+-dependent manner via LTCCs. This may also explain the multi-activation effects of LIPUS beyond neurons. LIPUS stimulation potentiates spontaneous neuronal activity by increasing Ca2+ influx.
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Affiliation(s)
- Wen-Yong Fan
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China
- Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yi-Ming Chen
- Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji University, Shanghai, 200070, China
| | - Yi-Fan Wang
- Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji University, Shanghai, 200070, China
| | - Yu-Qi Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China
- Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Jia-Qi Hu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China
- Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Center for Rehabilitation Medicine, Department of Pain Management, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, 310014, China
| | - Wen-Xu Tang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China
- Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yi Feng
- Department of Critical Care Medicine, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200080, China
| | - Qian Cheng
- Institute of Acoustics, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China.
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji University, Shanghai, 200070, China.
- Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai, 201210, China.
| | - Lei Xue
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200433, China.
- Department of Physiology and Neurobiology, School of Life Sciences, Fudan University, Shanghai, 200438, China.
- Research Institute of Intelligent Complex Systems, Fudan University, Shanghai, 200433, China.
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2
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Charlick JN, Bozadzhieva D, Butler AS, Wilkinson KA, Marrion NV. A single coiled-coil domain mutation in hIKCa channel subunits disrupts preferential formation of heteromeric hSK1:hIKCa channels. Eur J Neurosci 2024; 59:3-16. [PMID: 38018635 PMCID: PMC10952195 DOI: 10.1111/ejn.16189] [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: 02/09/2023] [Revised: 09/22/2023] [Accepted: 10/25/2023] [Indexed: 11/30/2023]
Abstract
The expression of IKCa (SK4) channel subunits overlaps with that of SK channel subunits, and it has been proposed that the two related subunits prefer to co-assemble to form heteromeric hSK1:hIKCa channels. This implicates hSK1:hIKCa heteromers in physiological roles that might have been attributed to activation of SK channels. We have used a mutation approach to confirm formation of heterometric hSK1:hIKCa channels. Introduction of residues within hSK1 that were predicted to impart sensitivity to the hIKCa current blocker TRAM-34 changed the pharmacology of functional heteromers. Heteromeric channels formed between wildtype hIKCa and mutant hSK1 subunits displayed a significantly higher sensitivity and maximum block to addition of TRAM-34 than heteromers formed between wildtype subunits. Heteromer formation was disrupted by a single point mutation within one COOH-terminal coiled-coil domain of the hIKCa channel subunit. This mutation only disrupted the formation of hSK1:hIKCa heteromeric channels, without affecting the formation of homomeric hIKCa channels. Finally, the Ca2+ gating sensitivity of heteromeric hSK1:hIKCa channels was found to be significantly lower than the Ca2+ gating sensitivity of homomeric hIKCa channels. These data confirmed the preferred formation of heteromeric channels that results from COOH-terminal interactions between subunits. The distinct sensitivity of the heteromer to activation by Ca2+ suggests that heteromeric channels fulfil a distinct function within those neurons that express both subunits.
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Affiliation(s)
- James N. Charlick
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Daniella Bozadzhieva
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Andrew S. Butler
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Kevin A. Wilkinson
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
| | - Neil V. Marrion
- School of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolUK
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3
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Maziar A, Critch TNRHY, Ghosh S, Rajani V, Flynn CM, Qin T, Reinhardt C, Man KNM, Lee A, Hell JW, Yuan Q. Aging differentially affects LTCC function in hippocampal CA1 and piriform cortex pyramidal neurons. Cereb Cortex 2023; 33:1489-1503. [PMID: 35437602 PMCID: PMC9930631 DOI: 10.1093/cercor/bhac152] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/25/2022] [Accepted: 03/27/2022] [Indexed: 11/14/2022] Open
Abstract
Aging is associated with cognitive decline and memory loss in humans. In rats, aging-associated neuronal excitability changes and impairments in learning have been extensively studied in the hippocampus. Here, we investigated the roles of L-type calcium channels (LTCCs) in the rat piriform cortex (PC), in comparison with those of the hippocampus. We employed spatial and olfactory tasks that involve the hippocampus and PC. LTCC blocker nimodipine administration impaired spontaneous location recognition in adult rats (6-9 months). However, the same blocker rescued the spatial learning deficiency in aged rats (19-23 months). In an odor-associative learning task, infusions of nimodipine into either the PC or dorsal CA1 impaired the ability of adult rats to learn a positive odor association. Again, in contrast, nimodipine rescued odor associative learning in aged rats. Aged CA1 neurons had higher somatic expression of LTCC Cav1.2 subunits, exhibited larger afterhyperpolarization (AHP) and lower excitability compared with adult neurons. In contrast, PC neurons from aged rats showed higher excitability and no difference in AHP. Cav1.2 expression was similar in adult and aged PC somata, but relatively higher in PSD95- puncta in aged dendrites. Our data suggest unique features of aging-associated changes in LTCCs in the PC and hippocampus.
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Affiliation(s)
- Aida Maziar
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Tristian N R H Y Critch
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Sourav Ghosh
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Vishaal Rajani
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Cassandra M Flynn
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Tian Qin
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Camila Reinhardt
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Kwun Nok Mimi Man
- Department of Pharmacology, School of Medicine, University of California-Davis, Sacramento, CA 95817, United States
| | - Amy Lee
- Department of Neuroscience, University of Texas-Austin, Austin, TX 78712, United States
| | - Johannes W Hell
- Department of Pharmacology, School of Medicine, University of California-Davis, Sacramento, CA 95817, United States
| | - Qi Yuan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
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4
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Zahra A, Liu R, Han W, Meng H, Wang Q, Wang Y, Campbell SL, Wu J. K Ca-Related Neurological Disorders: Phenotypic Spectrum and Therapeutic Indications. Curr Neuropharmacol 2023; 21:1504-1518. [PMID: 36503451 PMCID: PMC10472807 DOI: 10.2174/1570159x21666221208091805] [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: 04/21/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 12/14/2022] Open
Abstract
Although potassium channelopathies have been linked to a wide range of neurological conditions, the underlying pathogenic mechanism is not always clear, and a systematic summary of clinical manifestation is absent. Several neurological disorders have been associated with alterations of calcium-activated potassium channels (KCa channels), such as loss- or gain-of-function mutations, post-transcriptional modification, etc. Here, we outlined the current understanding of the molecular and cellular properties of three subtypes of KCa channels, including big conductance KCa channels (BK), small conductance KCa channels (SK), and the intermediate conductance KCa channels (IK). Next, we comprehensively reviewed the loss- or gain-of-function mutations of each KCa channel and described the corresponding mutation sites in specific diseases to broaden the phenotypic-genotypic spectrum of KCa-related neurological disorders. Moreover, we reviewed the current pharmaceutical strategies targeting KCa channels in KCa-related neurological disorders to provide new directions for drug discovery in anti-seizure medication.
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Affiliation(s)
- Aqeela Zahra
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Department of Zoology, University of Sialkot, Sialkot 51310, Pakistan
| | - Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - Wenzhe Han
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Meng
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - YunFu Wang
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Susan L. Campbell
- Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Jianping Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
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5
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Zhan X, Drummond-Main C, Greening D, Yao J, Chen SWR, Appendino JP, Au PYB, Turner RW. Cannabidiol counters the effects of a dominant-negative pathogenic Kv7.2 variant. iScience 2022; 25:105092. [PMID: 36157585 PMCID: PMC9490039 DOI: 10.1016/j.isci.2022.105092] [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: 06/02/2022] [Revised: 08/17/2022] [Accepted: 09/02/2022] [Indexed: 11/04/2022] Open
Abstract
Epilepsy and neurodevelopmental disorders can arise from pathogenic variants of KCNQ (Kv7) channels. A patient with developmental and epileptic encephalopathy exhibited an in-frame deletion of histidine 260 on Kv7.2. Coexpression of Kv7.2 mutant (mut) subunits with Kv7.3 invoked a decrease in current density, a depolarizing shift in voltage for activation, and a decrease in membrane conductance. Biotinylation revealed an increased level of surface Kv7.2mut compared to Kv7.3 with no change in total membrane protein expression. Super-resolution and FRET imaging confirmed heteromeric channel formation and a higher expression density of Kv7.2mut. Cannabidiol (1 μM) offset the effects of Kv7.2mut by inducing a hyperpolarizing shift in voltage for activation independent of CB1 or CB2 receptors. These data reveal that the ability for cannabidiol to reduce the effects of a pathogenic Kv7.2 variant supports its use as a potential therapeutic to reduce seizure activity. A patient with epileptic encephalopathy exhibits a Kv7.2 deletion at H260 (Kv7.2mut) Kv7.2mut shows increased expression at the membrane compared to Kv7.3 Kv7.2mut acts in a dominant-negative manner to reduce Kv7 conductance Cannabidiol acts on Kv7.x activation voltage to offset the effects of Kv7.2mut
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Affiliation(s)
- Xiaoqin Zhan
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Chris Drummond-Main
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Dylan Greening
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Jinjing Yao
- Libin Cardiovascular Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - S W R Chen
- Libin Cardiovascular Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - J P Appendino
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Pediatric Department, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - P Y Billie Au
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Department of Medical Genetics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ray W Turner
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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6
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Shin J, Kovacheva L, Thomas D, Stojanovic S, Knowlton CJ, Mankel J, Boehm J, Farassat N, Paladini C, Striessnig J, Canavier CC, Geisslinger G, Roeper J. Ca v1.3 calcium channels are full-range linear amplifiers of firing frequencies in lateral DA SN neurons. SCIENCE ADVANCES 2022; 8:eabm4560. [PMID: 35675413 PMCID: PMC9177074 DOI: 10.1126/sciadv.abm4560] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 04/22/2022] [Indexed: 05/12/2023]
Abstract
The low-threshold L-type calcium channel Cav1.3 accelerates the pacemaker rate in the heart, but its functional role for the extended dynamic range of neuronal firing is still unresolved. Here, we show that Cav1.3 calcium channels act as unexpectedly simple, full-range linear amplifiers of firing rates for lateral dopamine substantia nigra (DA SN) neurons in mice. This means that they boost in vitro or in vivo firing frequencies between 2 and 50 hertz by about 30%. Furthermore, we demonstrate that clinically relevant, low nanomolar concentrations of the L-type channel inhibitor isradipine selectively reduce the in vivo firing activity of these nigrostriatal DA SN neurons at therapeutic plasma concentrations. Thus, our study identifies the pacemaker function of neuronal Cav1.3 channels and provides direct evidence that repurposing dihydropyridines such as isradipine is feasible to selectively modulate the in vivo activity of highly vulnerable DA SN subpopulations in Parkinson's disease.
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Affiliation(s)
- Josef Shin
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Lora Kovacheva
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Dominique Thomas
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Frankfurt am Main, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP and Fraunhofer Cluster of Excellence for Immune Mediated Diseases CIMD, Frankfurt am Main, Germany
| | - Strahinja Stojanovic
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Christopher J. Knowlton
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Johanna Mankel
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Johannes Boehm
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Navid Farassat
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
| | - Carlos Paladini
- UTSA Neuroscience Institute, University of Texas at San Antonio, San Antonio, TX, USA
| | - Jörg Striessnig
- University of Innsbruck, Department of Pharmacology and Toxicology, Center for Molecular Biosciences, Innsbruck, Austria
| | - Carmen C. Canavier
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP and Fraunhofer Cluster of Excellence for Immune Mediated Diseases CIMD, Frankfurt am Main, Germany
| | - Gerd Geisslinger
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Frankfurt am Main, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP and Fraunhofer Cluster of Excellence for Immune Mediated Diseases CIMD, Frankfurt am Main, Germany
| | - Jochen Roeper
- Goethe University, Institute of Neurophysiology, Neuroscience Center, Frankfurt am Main, Germany
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7
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Ion Channel Partnerships: Odd and Not-So-Odd Couples Controlling Neuronal Ion Channel Function. Int J Mol Sci 2022; 23:ijms23041953. [PMID: 35216068 PMCID: PMC8878034 DOI: 10.3390/ijms23041953] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/05/2022] [Accepted: 02/08/2022] [Indexed: 12/04/2022] Open
Abstract
The concerted function of the large number of ion channels expressed in excitable cells, including brain neurons, shapes diverse signaling events by controlling the electrical properties of membranes. It has long been recognized that specific groups of ion channels are functionally coupled in mediating ionic fluxes that impact membrane potential, and that these changes in membrane potential impact ion channel gating. Recent studies have identified distinct sets of ion channels that can also physically and functionally associate to regulate the function of either ion channel partner beyond that afforded by changes in membrane potential alone. Here, we review canonical examples of such ion channel partnerships, in which a Ca2+ channel is partnered with a Ca2+-activated K+ channel to provide a dedicated route for efficient coupling of Ca2+ influx to K+ channel activation. We also highlight examples of non-canonical ion channel partnerships between Ca2+ channels and voltage-gated K+ channels that are not intrinsically Ca2+ sensitive, but whose partnership nonetheless yields enhanced regulation of one or the other ion channel partner. We also discuss how these ion channel partnerships can be shaped by the subcellular compartments in which they are found and provide perspectives on how recent advances in techniques to identify proteins in close proximity to one another in native cells may lead to an expanded knowledge of other ion channel partnerships.
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8
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Sahu G, Turner RW. The Molecular Basis for the Calcium-Dependent Slow Afterhyperpolarization in CA1 Hippocampal Pyramidal Neurons. Front Physiol 2022; 12:759707. [PMID: 35002757 PMCID: PMC8730529 DOI: 10.3389/fphys.2021.759707] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 12/02/2022] Open
Abstract
Neuronal signal transmission depends on the frequency, pattern, and timing of spike output, each of which are shaped by spike afterhyperpolarizations (AHPs). There are classically three post-spike AHPs of increasing duration categorized as fast, medium and slow AHPs that hyperpolarize a cell over a range of 10 ms to 30 s. Intensive early work on CA1 hippocampal pyramidal cells revealed that all three AHPs incorporate activation of calcium-gated potassium channels. The ionic basis for a fAHP was rapidly attributed to the actions of big conductance (BK) and the mAHP to small conductance (SK) or Kv7 potassium channels. In stark contrast, the ionic basis for a prominent slow AHP of up to 30 s duration remained an enigma for over 30 years. Recent advances in pharmacological, molecular, and imaging tools have uncovered the expression of a calcium-gated intermediate conductance potassium channel (IK, KCa3.1) in central neurons that proves to contribute to the slow AHP in CA1 hippocampal pyramidal cells. Together the data show that the sAHP arises in part from a core tripartite complex between Cav1.3 (L-type) calcium channels, ryanodine receptors, and IK channels at endoplasmic reticulum-plasma membrane junctions. Work on the sAHP in CA1 pyramidal neurons has again quickened pace, with identified contributions by both IK channels and the Na-K pump providing answers to several mysteries in the pharmacological properties of the sAHP.
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Affiliation(s)
- Giriraj Sahu
- National Institute of Pharmaceutical Education and Research Ahmedabad, Ahmedabad, India
| | - Ray W Turner
- Department Cell Biology & Anatomy, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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9
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Dixon RE, Navedo MF, Binder MD, Santana LF. Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters. Physiol Rev 2021; 102:1159-1210. [PMID: 34927454 DOI: 10.1152/physrev.00022.2021] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Cav1.2 and Cav1.3 channels to obligatory dimeric assembly and gating of voltage-gated Nav1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP3Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.
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Affiliation(s)
- Rose Ellen Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, United States
| | - Marc D Binder
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, United States
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
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10
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Hwang Y, Kim HC, Shin EJ. Repeated exposure to microcystin-leucine-arginine potentiates excitotoxicity induced by a low dose of kainate. Toxicology 2021; 460:152887. [PMID: 34352349 DOI: 10.1016/j.tox.2021.152887] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/15/2021] [Accepted: 07/30/2021] [Indexed: 02/08/2023]
Abstract
Microcystin-leucine-arginine (MLCR) is a cyanobacterial toxin, and has been demonstrated to cause neurotoxicity. In addition, MCLR has been identified as an inhibitor of protein phosphatase (PP)1 and PP2A, which are known to regulate the phosphorylation of various molecules related to synaptic excitability. Thus, in the present study, we examined whether MCLR exposure affects seizures induced by a low dose of kainic acid (KA; 0.05 μg, i.c.v.) administration. KA-induced seizure occurrence and seizure score significantly increased after repeated exposure to MCLR (2.5 or 5.0 μg/kg, i.p., once a day for 10 days), but not after acute MCLR exposure (2.5 or 5.0 μg/kg, i.p., 2 h and 30 min prior to KA administration), and hippocampal neuronal loss was consistently facilitated by repeated exposure to MCLR. In addition, repeated MCLR significantly elevated the membrane expression of kainate receptor GluK2 subunits, p-pan-protein kinase C (PKC), and p-extracellular signal-related kinase (ERK) at 1 h after KA. However, KA-induced membrane expression of Ca2+/calmodulin-dependent kinase II (CaMKII) was significantly reduced by repeated MCLR exposure. Consistent with the enhanced seizures and neurodegeneration, MCLR exposure significantly potentiated KA-induced oxidative stress and microglial activation, which was accompanied by increased expression of p-ERK and p-PKCδ in the hippocampus. The combined results suggest that repeated MCLR exposure potentiates KA-induced excitotoxicity in the hippocampus by increasing membrane GluK2 expression and enhancing oxidative stress and neuroinflammation through the modulation of p-CaMKII, p-PKC, and p-ERK.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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11
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Gandini MA, Zamponi GW. Voltage‐gated calcium channel nanodomains: molecular composition and function. FEBS J 2021; 289:614-633. [DOI: 10.1111/febs.15759] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Maria A. Gandini
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology Alberta Children’s Hospital Research Institute Hotchkiss Brain Institute Cumming School of Medicine University of Calgary AB Canada
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12
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Scott RC. Brains, complex systems and therapeutic opportunities in epilepsy. Seizure 2021; 90:155-159. [PMID: 33582003 DOI: 10.1016/j.seizure.2021.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 01/27/2021] [Accepted: 02/01/2021] [Indexed: 12/16/2022] Open
Abstract
The treatment of epilepsy remains extremely challenging for the thirty percent of people that do not become seizure free. This is despite the introduction of multiple new drugs over that last several decades, highlighting the need for new approaches to identifying novel therapeutic strategies. Conceptualizing the brain as a complex adaptive system and applying the tools that are used in addressing such systems provides an opportunity for expanding the space in which to search for new therapies. Epilepsy has long been considered a network disease at the level of whole brain connectivity, but the application of the concepts to gene and protein expression networks as well as to the dynamic behaviors of microcircuits has been underexplored. These levels of the brain complex adaptive system will be reviewed and a case made for the epilepsy community to embrace these concepts in order to reap to enormous potential rewards.
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Affiliation(s)
- Rod C Scott
- University of Vermont, 95 Carrigan Drive, Burlington, VT, 05405, United States; University of Vermont Medical Center, United States; Great Ormond Street Hospital for Children NHS Trust, United Kingdom.
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13
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Yeow SQZ, Loh KWZ, Soong TW. Calcium Channel Splice Variants and Their Effects in Brain and Cardiovascular Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:67-86. [DOI: 10.1007/978-981-16-4254-8_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Kim CH, Kim S, Kim SH, Roh J, Jin H, Song B. Role of densin-180 in mouse ventral hippocampal neurons in 24-hr retention of contextual fear conditioning. Brain Behav 2020; 10:e01891. [PMID: 33064361 PMCID: PMC7749528 DOI: 10.1002/brb3.1891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/01/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Densin-180 interacts with postsynaptic molecules including calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) but its function in learning and memory process has been unclear. METHODS To investigate a role of hippocampal densin-180 in contextual fear conditioning (CFC) learning and memory processes, knockdown (KD) of densin-180 in hippocampal subareas was applied. RESULTS First, ventral hippocampal (vHC) densin-180 KD impaired single-trial CFC (stCFC) memory one day later. stCFC caused freezing behaviors to reach the peak about one hour later in both control and KD mice, but then freezing was disappeared at 2 hr postshock in KD mice. Second, stCFC caused an immediate and transient reduction of vHC densin-180 in control mice, which was not observed in KD mice. Third, stCFC caused phosphorylated-T286 (p-T286) CaMKIIα to change similarly to densin-180, but p-T305 CaMKIIα was increased 1 hr later in control mice. In KD mice, these effects were gone. Moreover, both basal levels of p-T286 and p-T305 CaMKIIα were reduced without change in total CaMKIIα in KD mice. Fourth, we found double-trial CFC (dtCFC) memory acquisition and retrieval kinetics were different from those of stCFC in vHC KD mice. In addition, densin-180 in dorsal hippocampal area appeared to play its unique role during the very early retrieval period of both CFC memories. CONCLUSION This study shows that vHC densin-180 is necessary for stCFC memory formation and retrieval and suggests that both densin-180 and p-T305 CaMKIIα at 1 ~ 2 hr postshock are important for stCFC memory formation. We conclude that roles of hippocampal neuronal densin-180 in CFC are temporally dynamic and differential depending on the pattern of conditioning stimuli and its location along the dorsoventral axis of hippocampal formation.
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Affiliation(s)
- Chong-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Seoyul Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Su-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Jongtae Roh
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Harin Jin
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
| | - Bokyung Song
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul, Korea.,Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
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15
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Guo X, Fu Y, Zhang Y, Wang T, Lu L, Luo X, Wang K, Huang J, Xie T, Zheng C, Yang K, Tong J, Zuo L, Kang L, Tan Y, Jiang K, Li CSR, Luo X. Replicated risk CACNA1C variants for major psychiatric disorders may serve as potential therapeutic targets for the shared depressive endophenotype. JOURNAL OF NEUROSCIENCE & COGNITIVE STUDIES 2020; 4:1017. [PMID: 34046650 PMCID: PMC8153461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Genome-wide association studies (GWASs) have reported numerous associations between risk variants and major psychiatric disorders (MPDs) including schizophrenia (SCZ), bipolar disorder (BPD), major depressive disorder (MDD) and others. We reviewed all of the published GWASs, and extracted the genome-wide significant (p<10-6) and replicated associations between risk SNPs and MPDs. We found the associations of 6 variants located in 6 genes, including L type voltage-gated calcium channel (LTCCs) subunit alpha1 C gene (CACNA1C), that were genome-wide significant (2.0×10 -8 ≤p≤1.0×10 -6 ) and replicated at single-point level across at least two GWASs. Among them, the associations between MPDs and rs1006737 within CACNA1C are most robust. Thus, as a next step, the expression of the replicated risk genes in human hippocampus was analyzed. We found CACNA1C had significant mRNA expression in human hippocampus in two independent cohorts. Finally, we tried to elucidate the roles of venlafaxine and ω-3 PUFAs in the mRNA expression regulation of the replicated risk genes in hippocampus. We used cDNA chip-based microarray profiling to explore the transcriptome-wide mRNA expression regulation by ω-3 PUFAs (0.72/kg/d) and venlafaxine (0.25/kg/d) treatment in chronic mild stress (CMS) rats. ω-3 PUFAs and venlafaxine treatment elicited significant CACNA1C up-regulation. We concluded that CACNA1C might confer the genetic vulnerability to the shared depressive symptoms across MPDs and CACNA1C might be the therapeutic target for depressive endophenotype as well.
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Affiliation(s)
- Xiaoyun Guo
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P. R. China
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
- Cellular &Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Yingmei Fu
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P. R. China
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, P.R. China
| | - Yong Zhang
- Tianjin Mental Health Center, Tianjin 300222, China
| | - Tong Wang
- Cellular &Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Lu Lu
- Departments of Genetics, Genomics, Informatics, Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Xingqun Luo
- Department of Clinical Medicine, College of Integrated Traditional Chinese and Western Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350004, China
| | - Kesheng Wang
- Department of Biostatistics and Epidemiology, College of Public Health, East Tennessee State University, Johnson City, TN 37614, USA
| | - Juncao Huang
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
| | - Ting Xie
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
| | | | - Kebing Yang
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
| | - Jinghui Tong
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
| | - Lingjun Zuo
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Longli Kang
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Diseases of Tibet Autonomous Region, Xizang Minzu University School of Medicine, Xiangyang, Shaanxi 712082, China
| | - Yunlong Tan
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
| | - Kaida Jiang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P. R. China
| | - Chiang-shan R. Li
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Xingguang Luo
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
- Biological Psychiatry Research Center, Beijing Huilongguan Hospital, Beijing 100096, China
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16
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Pousinha PA, Mouska X, Bianchi D, Temido-Ferreira M, Rajão-Saraiva J, Gomes R, Fernandez SP, Salgueiro-Pereira AR, Gandin C, Raymond EF, Barik J, Goutagny R, Bethus I, Lopes LV, Migliore M, Marie H. The Amyloid Precursor Protein C-Terminal Domain Alters CA1 Neuron Firing, Modifying Hippocampus Oscillations and Impairing Spatial Memory Encoding. Cell Rep 2020; 29:317-331.e5. [PMID: 31597094 DOI: 10.1016/j.celrep.2019.08.103] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/09/2019] [Accepted: 08/29/2019] [Indexed: 12/15/2022] Open
Abstract
There is a growing consensus that Alzheimer's disease (AD) involves failure of the homeostatic machinery, which underlies the firing stability of neural circuits. What are the culprits leading to neuron firing instability? The amyloid precursor protein (APP) is central to AD pathogenesis, and we recently showed that its intracellular domain (AICD) could modify synaptic signal integration. We now hypothesize that AICD modifies neuron firing activity, thus contributing to the disruption of memory processes. Using cellular, electrophysiological, and behavioral techniques, we show that pathological AICD levels weaken CA1 neuron firing activity through a gene-transcription-dependent mechanism. Furthermore, increased AICD production in hippocampal neurons modifies oscillatory activity, specifically in the γ-frequency range, and disrupts spatial memory task. Collectively, our data suggest that AICD pathological levels, observed in AD mouse models and in human patients, might contribute to progressive neuron homeostatic failure, driving the shift from normal aging to AD.
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Affiliation(s)
| | - Xavier Mouska
- Université Côte d'Azur, CNRS UMR 7275, IPMC, Valbonne, France
| | - Daniela Bianchi
- Institute of Biophysics, National Research Council, Palermo, Italy
| | - Mariana Temido-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Universidade de Lisboa, Lisboa, Portugal
| | - Joana Rajão-Saraiva
- Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Universidade de Lisboa, Lisboa, Portugal
| | - Rui Gomes
- Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Universidade de Lisboa, Lisboa, Portugal
| | | | | | - Carine Gandin
- Université Côte d'Azur, CNRS UMR 7275, IPMC, Valbonne, France
| | | | - Jacques Barik
- Université Côte d'Azur, CNRS UMR 7275, IPMC, Valbonne, France
| | - Romain Goutagny
- Université de Strasbourg, CNRS UMR 7364, LNCA, Strasbourg, France
| | - Ingrid Bethus
- Université Côte d'Azur, CNRS UMR 7275, IPMC, Valbonne, France
| | - Luisa V Lopes
- Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Universidade de Lisboa, Lisboa, Portugal
| | - Michele Migliore
- Institute of Biophysics, National Research Council, Palermo, Italy
| | - Hélène Marie
- Université Côte d'Azur, CNRS UMR 7275, IPMC, Valbonne, France
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17
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Wang S, Cortes CJ. Interactions with PDZ proteins diversify voltage-gated calcium channel signaling. J Neurosci Res 2020; 99:332-348. [PMID: 32476168 DOI: 10.1002/jnr.24650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 11/12/2022]
Abstract
Voltage-gated Ca2+ (CaV ) channels are crucial for neuronal excitability and synaptic transmission upon depolarization. Their properties in vivo are modulated by their interaction with a variety of scaffolding proteins. Such interactions can influence the function and localization of CaV channels, as well as their coupling to intracellular second messengers and regulatory pathways, thus amplifying their signaling potential. Among these scaffolding proteins, a subset of PDZ (postsynaptic density-95, Drosophila discs-large, and zona occludens)-domain containing proteins play diverse roles in modulating CaV channel properties. At the presynaptic terminal, PDZ proteins enrich CaV channels in the active zone, enabling neurotransmitter release by maintaining a tight and vital link between channels and vesicles. In the postsynaptic density, these interactions are essential in regulating dendritic spine morphology and postsynaptic signaling cascades. In this review, we highlight the studies that demonstrate dynamic regulations of neuronal CaV channels by PDZ proteins. We discuss the role of PDZ proteins in controlling channel activity, regulating channel cell surface density, and influencing channel-mediated downstream signaling events. We highlight the importance of PDZ protein regulations of CaV channels and evaluate the link between this regulatory effect and human disease.
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Affiliation(s)
- Shiyi Wang
- Department of Cell Biology, Duke University, Durham, NC, USA.,Department of Neurology, Duke University, Durham, NC, USA
| | - Constanza J Cortes
- Department of Neurology, Duke University, Durham, NC, USA.,Department of Cell, Developmental and Integrative Biology, University of Alabama Birmingham, Birmingham, AL, USA
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18
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Protein Kinase A-Mediated Suppression of the Slow Afterhyperpolarizing KCa3.1 Current in Temporal Lobe Epilepsy. J Neurosci 2019; 39:9914-9926. [PMID: 31672789 DOI: 10.1523/jneurosci.1603-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 09/24/2019] [Accepted: 10/07/2019] [Indexed: 01/01/2023] Open
Abstract
Brain insults, such as trauma, stroke, anoxia, and status epilepticus (SE), cause multiple changes in synaptic function and intrinsic properties of surviving neurons that may lead to the development of epilepsy. Experimentally, a single SE episode, induced by the convulsant pilocarpine, initiates the development of an epileptic condition resembling human temporal lobe epilepsy (TLE). Principal hippocampal neurons from such epileptic animals display enhanced spike output in response to excitatory stimuli compared with neurons from nonepileptic animals. This enhanced firing is negatively related to the size of the slow afterhyperpolarization (sAHP), which is reduced in the epileptic neurons. The sAHP is an intrinsic neuronal negative feedback mechanism consisting normally of two partially overlapping components produced by disparate mechanisms. One component is generated by activation of Ca2+-gated K+ (KCa) channels, likely KCa3.1, consequent to spike Ca2+ influx (the KCa-sAHP component). The second component is generated by enhancement of the electrogenic Na+/K+ ATPase (NKA) by spike Na+ influx (NKA-sAHP component). Here we show that the KCa-sAHP component is markedly reduced in male rat epileptic neurons, whereas the NKA-sAHP component is not altered. The KCa-sAHP reduction is due to the downregulation of KCa3.1 channels, mediated by cAMP-dependent protein kinase A (PKA). This sustained effect can be acutely reversed by applying PKA inhibitors, leading also to normalization of the spike output of epileptic neurons. We propose that the novel "acquired channelopathy" described here, namely, PKA-mediated downregulation of KCa3.1 activity, provides an innovative target for developing new treatments for TLE, hopefully overcoming the pharmacoresistance to traditional drugs.SIGNIFICANCE STATEMENT Epilepsy, a common neurological disorder, often develops following a brain insult. Identifying key molecular and cellular mechanisms underlying acquired epilepsy is critical for developing effective antiepileptic therapies. In an experimental model of acquired epilepsy, we show that principal hippocampal neurons become intrinsically hyperexcitable. This alteration is due predominantly to the downregulation of a ubiquitous class of potassium ion channels, KCa3.1, whose main function is to dampen neuronal excitability. KCa3.1 downregulation is mediated by the cAMP-dependent protein kinase A (PKA) signaling pathway. Most importantly, it can be acutely reversed by PKA inhibitors, leading to recovery of KCa3.1 function and normalization of neuronal excitability. The discovery of this novel epileptogenic mechanism hopefully will facilitate the development of more efficient pharmacotherapy for acquired epilepsy.
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19
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Junctophilin Proteins Tether a Cav1-RyR2-KCa3.1 Tripartite Complex to Regulate Neuronal Excitability. Cell Rep 2019; 28:2427-2442.e6. [DOI: 10.1016/j.celrep.2019.07.075] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/20/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022] Open
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20
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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21
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Higham J, Sahu G, Wazen RM, Colarusso P, Gregorie A, Harvey BSJ, Goudswaard L, Varley G, Sheppard DN, Turner RW, Marrion NV. Preferred Formation of Heteromeric Channels between Coexpressed SK1 and IKCa Channel Subunits Provides a Unique Pharmacological Profile of Ca 2+-Activated Potassium Channels. Mol Pharmacol 2019; 96:115-126. [PMID: 31048549 DOI: 10.1124/mol.118.115634] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/27/2019] [Indexed: 01/19/2023] Open
Abstract
Three small conductance calcium-activated potassium channel (SK) subunits have been cloned and found to preferentially form heteromeric channels when expressed in a heterologous expression system. The original cloning of the gene encoding the intermediate conductance calcium-activated potassium channel (IKCa) was termed SK4 because of the high homology between channel subtypes. Recent immunovisualization suggests that IKCa is expressed in the same subcellular compartments of some neurons as SK channel subunits. Stochastic optical reconstruction microscopy super-resolution microscopy revealed that coexpressed IKCa and SK1 channel subunits were closely associated, a finding substantiated by measurement of fluorescence resonance energy transfer between coexpressed fluorophore-tagged subunits. Expression of homomeric SK1 channels produced current that displayed typical sensitivity to SK channel inhibitors, while expressed IKCa channel current was inhibited by known IKCa channel blockers. Expression of both SK1 and IKCa subunits gave a current that displayed no sensitivity to SK channel inhibitors and a decreased sensitivity to IKCa current inhibitors. Single channel recording indicated that coexpression of SK1 and IKCa subunits produced channels with properties intermediate between those observed for homomeric channels. These data indicate that SK1 and IKCa channel subunits preferentially combine to form heteromeric channels that display pharmacological and biophysical properties distinct from those seen with homomeric channels.
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Affiliation(s)
- James Higham
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Giriraj Sahu
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rima-Marie Wazen
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Pina Colarusso
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Alice Gregorie
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Bartholomew S J Harvey
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Lucy Goudswaard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gemma Varley
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ray W Turner
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Neil V Marrion
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom (J.H., A.G., B.S.J.H., L.G., G.V., D.N.S., N.V.M.); and Hotchkiss Brain Institute (G.S., R.W.T.) and Snyder Institute for Chronic Diseases (R.-M.W., P.C.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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22
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Moore AR, Richards SE, Kenny K, Royer L, Chan U, Flavahan K, Van Hooser SD, Paradis S. Rem2 stabilizes intrinsic excitability and spontaneous firing in visual circuits. eLife 2018; 7:e33092. [PMID: 29809135 PMCID: PMC6010341 DOI: 10.7554/elife.33092] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/28/2018] [Indexed: 12/20/2022] Open
Abstract
Sensory experience plays an important role in shaping neural circuitry by affecting the synaptic connectivity and intrinsic properties of individual neurons. Identifying the molecular players responsible for converting external stimuli into altered neuronal output remains a crucial step in understanding experience-dependent plasticity and circuit function. Here, we investigate the role of the activity-regulated, non-canonical Ras-like GTPase Rem2 in visual circuit plasticity. We demonstrate that Rem2-/- mice fail to exhibit normal ocular dominance plasticity during the critical period. At the cellular level, our data establish a cell-autonomous role for Rem2 in regulating intrinsic excitability of layer 2/3 pyramidal neurons, prior to changes in synaptic function. Consistent with these findings, both in vitro and in vivo recordings reveal increased spontaneous firing rates in the absence of Rem2. Taken together, our data demonstrate that Rem2 is a key molecule that regulates neuronal excitability and circuit function in the context of changing sensory experience.
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Affiliation(s)
- Anna R Moore
- Department of BiologyBrandeis UniversityWalthamUnited States
| | - Sarah E Richards
- Department of BiologyBrandeis UniversityWalthamUnited States
- Volen Center for Complex SystemsBrandeis UniversityWalthamUnited States
| | - Katelyn Kenny
- National Center for Behavioral GenomicsBrandeis UniversityWalthamUnited States
| | - Leandro Royer
- Department of BiologyBrandeis UniversityWalthamUnited States
| | - Urann Chan
- Department of BiologyBrandeis UniversityWalthamUnited States
| | - Kelly Flavahan
- Department of BiologyBrandeis UniversityWalthamUnited States
| | - Stephen D Van Hooser
- Department of BiologyBrandeis UniversityWalthamUnited States
- Volen Center for Complex SystemsBrandeis UniversityWalthamUnited States
| | - Suzanne Paradis
- Department of BiologyBrandeis UniversityWalthamUnited States
- Volen Center for Complex SystemsBrandeis UniversityWalthamUnited States
- National Center for Behavioral GenomicsBrandeis UniversityWalthamUnited States
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