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Hughes BA, O'Buckley TK, Boero G, Morrow AL. Interneuron-Selective HCN Channel Knockdown in Prelimbic Cortex of Female Rats Mimics Effects of Chronic Ethanol Exposure. Alcohol 2024:S0741-8329(24)00099-5. [PMID: 39033967 DOI: 10.1016/j.alcohol.2024.07.005] [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: 04/25/2024] [Revised: 07/16/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024]
Abstract
Our laboratory has previously shown that chronic ethanol exposure elicits enhanced working memory performance in female, but not male, adult Sprague-Dawley rats, indicative of a fundamental sex difference in cortical plasticity. Recent studies have furthermore revealed that females display markedly reduced HCN-mediated channel activity in inhibitory Martinotti interneurons after chronic ethanol exposure that is similarly not observed in males. From these observations we hypothesized that alcohol elicits facilitated working memory performance via down-regulation of these channels' activity specifically within interneurons. To test this hypothesis, we employed a Pol-II compatible shRNA expression system to elicit targeted knockdown of HCN channel activity in these cells, and measured performance on a delayed Non-Match-to-Sample (NMS) T-maze test to gauge effects on working memory performance. A significant baseline enhancement of working memory performance with HCN channel knockdown was observed, indicative of a critical role for interneuron-expressed HCNs in maintaining optimal cortical network activity during cognitively-demanding tasks. Consistent with previous observations, ethanol exposure resulted in enhanced NMS T-maze performance, however elevated working memory performance was observed in both scram- and hcn-shRNA infected groups after alcohol administration. We therefore conclude that interneuron-expressed HCN channels, despite representing a minor population of total cortical HCN expression, contribute substantially to maintaining working memory processes. Downregulated HCN channel activity, though, does not alone appear sufficient to manifest alcohol-induced enhancement of working memory performance observed in female rats during acute withdrawal.
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Affiliation(s)
- Benjamin A Hughes
- Department of Psychiatry, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599; Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Todd K O'Buckley
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Giorgia Boero
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - A Leslie Morrow
- Department of Psychiatry, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599; Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599.
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Goniotaki D, Tamagnini F, Biasetti L, Rumpf SL, Troakes C, Pollack SJ, Ukwesa S, Sun H, Kraev I, Serpell LC, Noble W, Staras K, Hanger DP. Tau-mediated synaptic dysfunction is coupled with HCN channelopathy. Alzheimers Dement 2024. [PMID: 38994745 DOI: 10.1002/alz.14074] [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: 01/29/2024] [Revised: 05/01/2024] [Accepted: 05/25/2024] [Indexed: 07/13/2024]
Abstract
INTRODUCTION In tauopathies, altered tau processing correlates with impairments in synaptic density and function. Changes in hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contribute to disease-associated abnormalities in multiple neurodegenerative diseases. METHODS To investigate the link between tau and HCN channels, we performed histological, biochemical, ultrastructural, and functional analyses of hippocampal tissues from Alzheimer's disease (AD), age-matched controls, Tau35 mice, and/or Tau35 primary hippocampal neurons. RESULTS Expression of specific HCN channels is elevated in post mortem AD hippocampus. Tau35 mice develop progressive abnormalities including increased phosphorylated tau, enhanced HCN channel expression, decreased dendritic branching, reduced synapse density, and vesicle clustering defects. Tau35 primary neurons show increased HCN channel expression enhanced hyperpolarization-induced membrane voltage "sag" and changes in the frequency and kinetics of spontaneous excitatory postsynaptic currents. DISCUSSION Our findings are consistent with a model in which pathological changes in tauopathies impact HCN channels to drive network-wide structural and functional synaptic deficits. HIGHLIGHTS Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are functionally linked to the development of tauopathy. Expression of specific HCN channels is elevated in the hippocampus in Alzheimer's disease and the Tau35 mouse model of tauopathy. Increased expression of HCN channels in Tau35 mice is accompanied by hyperpolarization-induced membrane voltage "sag" demonstrating a detrimental effect of tau abnormalities on HCN channel function. Tau35 expression alters synaptic organization, causing a loosened vesicle clustering phenotype in Tau35 mice.
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Affiliation(s)
- Despoina Goniotaki
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Francesco Tamagnini
- Department of Pharmacy, School of Chemistry, Food and Pharmacy, University of Reading, Reading, UK
| | - Luca Biasetti
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, UK
| | - Svenja-Lotta Rumpf
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Claire Troakes
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Saskia J Pollack
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Shalom Ukwesa
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Haoyue Sun
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Igor Kraev
- Electron Microscopy Suite, STEM Faculty, The Open University, Milton Keynes, UK
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, UK
| | - Wendy Noble
- Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Kevin Staras
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, UK
| | - Diane P Hanger
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
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Lai S, Zhang L, Tu X, Ma X, Song Y, Cao K, Li M, Meng J, Shi Y, Wu Q, Yang C, Lan Z, Lau CG, Shi J, Ma W, Li S, Xue YX, Huang Z. Termination of convulsion seizures by destabilizing and perturbing seizure memory engrams. SCIENCE ADVANCES 2024; 10:eadk9484. [PMID: 38507477 PMCID: PMC10954199 DOI: 10.1126/sciadv.adk9484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 02/13/2024] [Indexed: 03/22/2024]
Abstract
Epileptogenesis, arising from alterations in synaptic strength, shares mechanistic and phenotypic parallels with memory formation. However, direct evidence supporting the existence of seizure memory remains scarce. Leveraging a conditioned seizure memory (CSM) paradigm, we found that CSM enabled the environmental cue to trigger seizure repetitively, and activating cue-responding engram cells could generate CSM artificially. Moreover, cue exposure initiated an analogous process of memory reconsolidation driven by mammalian target of rapamycin-brain-derived neurotrophic factor signaling. Pharmacological targeting of the mammalian target of rapamycin pathway within a limited time window reduced seizures in animals and interictal epileptiform discharges in patients with refractory seizures. Our findings reveal a causal link between seizure memory engrams and seizures, which leads us to a deeper understanding of epileptogenesis and points to a promising direction for epilepsy treatment.
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Affiliation(s)
- Shirong Lai
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
- School of Health Management, Xihua University, Chengdu 610039, China
| | - Libo Zhang
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing 100191, China
- Shenzhen Public Service Platform for Clinical Application of Medical Imaging, Shenzhen Key Laboratory for Drug Addiction and Medication Safety, Department of Ultrasound, Peking University Shenzhen Hospital, Shenzhen-PKU-HKUST Medical Center, Shenzhen 518036, China
| | - Xinyu Tu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Xinyue Ma
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yujing Song
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Kexin Cao
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing 100191, China
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Miaomiao Li
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110022, China
| | - Jihong Meng
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110022, China
| | - Yiqiang Shi
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Qing Wu
- School of Health Management, Xihua University, Chengdu 610039, China
| | - Chen Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Zifan Lan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | | | - Jie Shi
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing 100191, China
| | - Weining Ma
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110022, China
| | - Shaoyi Li
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110022, China
| | - Yan-Xue Xue
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing 100191, China
- Chinese Institute for Brain Research, Beijing 102206, China
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
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Yuan T, Wang Y, Jin Y, Yang H, Xu S, Zhang H, Chen Q, Li N, Ma X, Song H, Peng C, Geng Z, Dong J, Duan G, Sun Q, Yang Y, Yang F, Huang Z. Coupling of Slack and Na V1.6 sensitizes Slack to quinidine blockade and guides anti-seizure strategy development. eLife 2024; 12:RP87559. [PMID: 38289338 PMCID: PMC10942592 DOI: 10.7554/elife.87559] [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] [Indexed: 02/01/2024] Open
Abstract
Quinidine has been used as an anticonvulsant to treat patients with KCNT1-related epilepsy by targeting gain-of-function KCNT1 pathogenic mutant variants. However, the detailed mechanism underlying quinidine's blockade against KCNT1 (Slack) remains elusive. Here, we report a functional and physical coupling of the voltage-gated sodium channel NaV1.6 and Slack. NaV1.6 binds to and highly sensitizes Slack to quinidine blockade. Homozygous knockout of NaV1.6 reduces the sensitivity of native sodium-activated potassium currents to quinidine blockade. NaV1.6-mediated sensitization requires the involvement of NaV1.6's N- and C-termini binding to Slack's C-terminus and is enhanced by transient sodium influx through NaV1.6. Moreover, disrupting the Slack-NaV1.6 interaction by viral expression of Slack's C-terminus can protect against SlackG269S-induced seizures in mice. These insights about a Slack-NaV1.6 complex challenge the traditional view of 'Slack as an isolated target' for anti-epileptic drug discovery efforts and can guide the development of innovative therapeutic strategies for KCNT1-related epilepsy.
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Affiliation(s)
- Tian Yuan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Yifan Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Yuchen Jin
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Hui Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Shuai Xu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Heng Zhang
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang UniversityZhejiangChina
| | - Qian Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Na Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Xinyue Ma
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Huifang Song
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Chao Peng
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Ze Geng
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Jie Dong
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Guifang Duan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Qi Sun
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue UniversityWest LafayetteUnited States
| | - Fan Yang
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang UniversityZhejiangChina
- Department of Biophysics, Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, HangzhouZhejiangChina
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science CenterBeijingChina
- IDG/McGovern Institute for Brain Research, Peking UniversityBeijingChina
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Topczewska A, Giacalone E, Pratt WS, Migliore M, Dolphin AC, Shah MM. T-type Ca 2+ and persistent Na + currents synergistically elevate ventral, not dorsal, entorhinal cortical stellate cell excitability. Cell Rep 2023; 42:112699. [PMID: 37368752 PMCID: PMC10687207 DOI: 10.1016/j.celrep.2023.112699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 03/08/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Dorsal and ventral medial entorhinal cortex (mEC) regions have distinct neural network firing patterns to differentially support functions such as spatial memory. Accordingly, mEC layer II dorsal stellate neurons are less excitable than ventral neurons. This is partly because the densities of inhibitory conductances are higher in dorsal than ventral neurons. Here, we report that T-type Ca2+ currents increase 3-fold along the dorsal-ventral axis in mEC layer II stellate neurons, with twice as much CaV3.2 mRNA in ventral mEC compared with dorsal mEC. Long depolarizing stimuli trigger T-type Ca2+ currents, which interact with persistent Na+ currents to elevate the membrane voltage and spike firing in ventral, not dorsal, neurons. T-type Ca2+ currents themselves prolong excitatory postsynaptic potentials (EPSPs) to enhance their summation and spike coupling in ventral neurons only. These findings indicate that T-type Ca2+ currents critically influence the dorsal-ventral mEC stellate neuron excitability gradient and, thereby, mEC dorsal-ventral circuit activity.
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Affiliation(s)
| | | | - Wendy S Pratt
- Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Michele Migliore
- Institute of Biophysics, National Research Council, 90146 Palermo, Italy
| | - Annette C Dolphin
- Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Mala M Shah
- Pharmacology, School of Pharmacy, University College London, London WC1N 4AX, UK.
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Willis DE, Goldstein PA. Targeting Affective Mood Disorders With Ketamine to Prevent Chronic Postsurgical Pain. FRONTIERS IN PAIN RESEARCH 2022; 3:872696. [PMID: 35832728 PMCID: PMC9271565 DOI: 10.3389/fpain.2022.872696] [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: 02/09/2022] [Accepted: 06/06/2022] [Indexed: 12/02/2022] Open
Abstract
The phencyclidine-derivative ketamine [2-(2-chlorophenyl)-2-(methylamino)cyclohexan-1-one] was added to the World Health Organization's Model List of Essential Medicines in 1985 and is also on the Model List of Essential Medicines for Children due to its efficacy and safety as an intravenous anesthetic. In sub-anesthetic doses, ketamine is an effective analgesic for the treatment of acute pain (such as may occur in the perioperative setting). Additionally, ketamine may have efficacy in relieving some forms of chronic pain. In 2019, Janssen Pharmaceuticals received regulatory-approval in both the United States and Europe for use of the S-enantiomer of ketamine in adults living with treatment-resistant major depressive disorder. Pre-existing anxiety/depression and the severity of postoperative pain are risk factors for development of chronic postsurgical pain. An important question is whether short-term administration of ketamine can prevent the conversion of acute postsurgical pain to chronic postsurgical pain. Here, we have reviewed ketamine's effects on the biopsychological processes underlying pain perception and affective mood disorders, focusing on non-NMDA receptor-mediated effects, with an emphasis on results from human trials where available.
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Affiliation(s)
- Dianna E. Willis
- Burke Neurological Institute, White Plains, NY, United States
- Feil Family Brain and Mind Institute, Weill Cornell Medicine, New York, NY, United States
| | - Peter A. Goldstein
- Feil Family Brain and Mind Institute, Weill Cornell Medicine, New York, NY, United States
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, United States
- Department of Medicine, Weill Cornell Medicine, New York, NY, United States
- *Correspondence: Peter A. Goldstein
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Kessi M, Peng J, Duan H, He H, Chen B, Xiong J, Wang Y, Yang L, Wang G, Kiprotich K, Bamgbade OA, He F, Yin F. The Contribution of HCN Channelopathies in Different Epileptic Syndromes, Mechanisms, Modulators, and Potential Treatment Targets: A Systematic Review. Front Mol Neurosci 2022; 15:807202. [PMID: 35663267 PMCID: PMC9161305 DOI: 10.3389/fnmol.2022.807202] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
Background Hyperpolarization-activated cyclic nucleotide-gated (HCN) current reduces dendritic summation, suppresses dendritic calcium spikes, and enables inhibitory GABA-mediated postsynaptic potentials, thereby suppressing epilepsy. However, it is unclear whether increased HCN current can produce epilepsy. We hypothesized that gain-of-function (GOF) and loss-of-function (LOF) variants of HCN channel genes may cause epilepsy. Objectives This systematic review aims to summarize the role of HCN channelopathies in epilepsy, update genetic findings in patients, create genotype–phenotype correlations, and discuss animal models, GOF and LOF mechanisms, and potential treatment targets. Methods The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, for all years until August 2021. Results We identified pathogenic variants of HCN1 (n = 24), HCN2 (n = 8), HCN3 (n = 2), and HCN4 (n = 6) that were associated with epilepsy in 74 cases (43 HCN1, 20 HCN2, 2 HCN3, and 9 HCN4). Epilepsy was associated with GOF and LOF variants, and the mechanisms were indeterminate. Less than half of the cases became seizure-free and some developed drug-resistant epilepsy. Of the 74 cases, 12 (16.2%) died, comprising HCN1 (n = 4), HCN2 (n = 2), HCN3 (n = 2), and HCN4 (n = 4). Of the deceased cases, 10 (83%) had a sudden unexpected death in epilepsy (SUDEP) and 2 (16.7%) due to cardiopulmonary failure. SUDEP affected more adults (n = 10) than children (n = 2). HCN1 variants p.M234R, p.C329S, p.V414M, p.M153I, and p.M305L, as well as HCN2 variants p.S632W and delPPP (p.719–721), were associated with different phenotypes. HCN1 p.L157V and HCN4 p.R550C were associated with genetic generalized epilepsy. There are several HCN animal models, pharmacological targets, and modulators, but precise drugs have not been developed. Currently, there are no HCN channel openers. Conclusion We recommend clinicians to include HCN genes in epilepsy gene panels. Researchers should explore the possible underlying mechanisms for GOF and LOF variants by identifying the specific neuronal subtypes and neuroanatomical locations of each identified pathogenic variant. Researchers should identify specific HCN channel openers and blockers with high binding affinity. Such information will give clarity to the involvement of HCN channelopathies in epilepsy and provide the opportunity to develop targeted treatments.
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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
- Department of Pediatrics, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Haolin Duan
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Hailan He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Juan Xiong
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Ying Wang
- 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
| | - Guoli Wang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Karlmax Kiprotich
- Department of Epidemiology and Medical Statistics, School of Public Health, Moi University, Eldoret, Kenya
| | - Olumuyiwa A. Bamgbade
- Department of Anesthesiology and Pharmacology, University of British Columbia, Vancouver, BC, Canada
| | - Fang He
- 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
- *Correspondence: Fei Yin
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Santoro B, Shah MM. Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels as Drug Targets for Neurological Disorders. Annu Rev Pharmacol Toxicol 2020; 60:109-131. [PMID: 31914897 DOI: 10.1146/annurev-pharmtox-010919-023356] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are voltage-gated ion channels that critically modulate neuronal activity. Four HCN subunits (HCN1-4) have been cloned, each having a unique expression profile and distinctive effects on neuronal excitability within the brain. Consistent with this, the expression and function of these subunits are altered in diverse ways in neurological disorders. Here, we review current knowledge on the structure and distribution of the individual HCN channel isoforms, their effects on neuronal activity under physiological conditions, and how their expression and function are altered in neurological disorders, particularly epilepsy, neuropathic pain, and affective disorders. We discuss the suitability of HCN channels as therapeutic targets and how drugs might be strategically designed to specifically act on particular isoforms. We conclude that medicines that target individual HCN isoforms and/or their auxiliary subunit, TRIP8b, may provide valuable means of treating distinct neurological conditions.
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Affiliation(s)
- Bina Santoro
- Department of Neuroscience, Columbia University, New York, NY 10027, USA
| | - Mala M Shah
- Department of Pharmacology, School of Pharmacy, University College London, London WC1N 1AX, United Kingdom;
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Jin X, Chen Q, Song Y, Zheng J, Xiao K, Shao S, Fu Z, Yi M, Yang Y, Huang Z. Dopamine D2 receptors regulate the action potential threshold by modulating T‐type calcium channels in stellate cells of the medial entorhinal cortex. J Physiol 2019; 597:3363-3387. [PMID: 31049961 DOI: 10.1113/jp277976] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 04/24/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Xueqin Jin
- State Key Laboratory of Natural and Biomimetic DrugsDepartment of Molecular and Cellular PharmacologySchool of Pharmaceutical SciencesPeking University Health Science Centre Beijing 100191 China
| | - Qian Chen
- State Key Laboratory of Natural and Biomimetic DrugsDepartment of Molecular and Cellular PharmacologySchool of Pharmaceutical SciencesPeking University Health Science Centre Beijing 100191 China
| | - Yan Song
- State Key Laboratory of Natural and Biomimetic DrugsDepartment of Molecular and Cellular PharmacologySchool of Pharmaceutical SciencesPeking University Health Science Centre Beijing 100191 China
| | - Jie Zheng
- Neuroscience Research InstitutePeking University Health Science Center Beijing 100191 China
| | - Kuo Xiao
- State Key Laboratory of Natural and Biomimetic DrugsDepartment of Molecular and Cellular PharmacologySchool of Pharmaceutical SciencesPeking University Health Science Centre Beijing 100191 China
| | - Shan Shao
- Neuroscience Research InstitutePeking University Health Science Center Beijing 100191 China
| | - Zibing Fu
- Neuroscience Research InstitutePeking University Health Science Center Beijing 100191 China
| | - Ming Yi
- Neuroscience Research InstitutePeking University Health Science Center Beijing 100191 China
- Key Laboratory for NeuroscienceMinistry of Education/National Health and Family Planning CommissionPeking University Beijing 100191 China
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular PharmacologyCollege of Pharmacy, Purdue University West Lafayette IN 47907 USA
- Purdue Institute for Integrative Neuroscience 575 Stadium Mall Drive West Lafayette IN 47907 USA
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic DrugsDepartment of Molecular and Cellular PharmacologySchool of Pharmaceutical SciencesPeking University Health Science Centre Beijing 100191 China
- Key Laboratory for NeuroscienceMinistry of Education/National Health and Family Planning CommissionPeking University Beijing 100191 China
- Department of Molecular and Cellular PharmacologyPeking University Health Science Center 38 Xue Yuan Road Beijing 100191 China
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10
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Martinello K, Giacalone E, Migliore M, Brown DA, Shah MM. The subthreshold-active K V7 current regulates neurotransmission by limiting spike-induced Ca 2+ influx in hippocampal mossy fiber synaptic terminals. Commun Biol 2019; 2:145. [PMID: 31044170 PMCID: PMC6486593 DOI: 10.1038/s42003-019-0408-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/29/2019] [Indexed: 12/23/2022] Open
Abstract
Little is known about the properties and function of ion channels that affect synaptic terminal-resting properties. One particular subthreshold-active ion channel, the Kv7 potassium channel, is highly localized to axons, but its role in regulating synaptic terminal intrinsic excitability and release is largely unexplored. Using electrophysiological recordings together with computational modeling, we found that the KV7 current was active at rest in adult hippocampal mossy fiber synaptic terminals and enhanced their membrane conductance. The current also restrained action potential-induced Ca2+ influx via N- and P/Q-type Ca2+ channels in boutons. This was associated with a substantial reduction in the spike half-width and afterdepolarization following presynaptic spikes. Further, by constraining spike-induced Ca2+ influx, the presynaptic KV7 current decreased neurotransmission onto CA3 pyramidal neurons and short-term synaptic plasticity at the mossy fiber-CA3 synapse. This is a distinctive mechanism by which KV7 channels influence hippocampal neuronal excitability and synaptic plasticity.
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Affiliation(s)
| | | | - Michele Migliore
- Institute of Biophysics, National Research Council, 90146 Palermo, Italy
| | - David A. Brown
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT UK
| | - Mala M. Shah
- UCL School of Pharmacy University College London, London, WC1N 1AX UK
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11
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Günther A, Luczak V, Gruteser N, Abel T, Baumann A. HCN4 knockdown in dorsal hippocampus promotes anxiety-like behavior in mice. GENES BRAIN AND BEHAVIOR 2019; 18:e12550. [PMID: 30585408 PMCID: PMC6850037 DOI: 10.1111/gbb.12550] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 12/03/2018] [Accepted: 12/22/2018] [Indexed: 12/29/2022]
Abstract
Hyperpolarization‐activated and cyclic nucleotide‐gated (HCN) channels mediate the Ih current in the murine hippocampus. Disruption of the Ih current by knockout of HCN1, HCN2 or tetratricopeptide repeat‐containing Rab8b‐interacting protein has been shown to affect physiological processes such as synaptic integration and maintenance of resting membrane potentials as well as several behaviors in mice, including depressive‐like and anxiety‐like behaviors. However, the potential involvement of the HCN4 isoform in these processes is unknown. Here, we assessed the contribution of the HCN4 isoform to neuronal processing and hippocampus‐based behaviors in mice. We show that HCN4 is expressed in various regions of the hippocampus, with distinct expression patterns that partially overlapped with other HCN isoforms. For behavioral analysis, we specifically modulated HCN4 expression by injecting recombinant adeno‐associated viral (rAAV) vectors mediating expression of short hairpin RNA against hcn4 (shHcn4) into the dorsal hippocampus of mice. HCN4 knockdown produced no effect on contextual fear conditioning or spatial memory. However, a pronounced anxiogenic effect was evident in mice treated with shHcn4 compared to control littermates. Our findings suggest that HCN4 specifically contributes to anxiety‐like behaviors in mice.
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Affiliation(s)
- Anne Günther
- Laboratory for Synaptic Molecules of Memory Persistence, Center for Brain Science, RIKEN, Saitama, Japan.,Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Vincent Luczak
- Division of Biological Sciences and Center for Neural Circuits and Behavior, Neurobiology Section, Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, California, USA
| | - Nadine Gruteser
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Ted Abel
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Arnd Baumann
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
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12
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Inhibition of Hsp70 Suppresses Neuronal Hyperexcitability and Attenuates Epilepsy by Enhancing A-Type Potassium Current. Cell Rep 2019; 26:168-181.e4. [DOI: 10.1016/j.celrep.2018.12.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 10/06/2018] [Accepted: 12/06/2018] [Indexed: 01/03/2023] Open
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13
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Zobeiri M, Chaudhary R, Datunashvili M, Heuermann RJ, Lüttjohann A, Narayanan V, Balfanz S, Meuth P, Chetkovich DM, Pape HC, Baumann A, van Luijtelaar G, Budde T. Modulation of thalamocortical oscillations by TRIP8b, an auxiliary subunit for HCN channels. Brain Struct Funct 2018; 223:1537-1564. [PMID: 29168010 PMCID: PMC5869905 DOI: 10.1007/s00429-017-1559-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/30/2017] [Indexed: 12/16/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels have important functions in controlling neuronal excitability and generating rhythmic oscillatory activity. The role of tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) in regulation of hyperpolarization-activated inward current, I h, in the thalamocortical system and its functional relevance for the physiological thalamocortical oscillations were investigated. A significant decrease in I h current density, in both thalamocortical relay (TC) and cortical pyramidal neurons was found in TRIP8b-deficient mice (TRIP8b-/-). In addition basal cAMP levels in the brain were found to be decreased while the availability of the fast transient A-type K+ current, I A, in TC neurons was increased. These changes were associated with alterations in intrinsic properties and firing patterns of TC neurons, as well as intrathalamic and thalamocortical network oscillations, revealing a significant increase in slow oscillations in the delta frequency range (0.5-4 Hz) during episodes of active-wakefulness. In addition, absence of TRIP8b suppresses the normal desynchronization response of the EEG during the switch from slow-wave sleep to wakefulness. It is concluded that TRIP8b is necessary for the modulation of physiological thalamocortical oscillations due to its direct effect on HCN channel expression in thalamus and cortex and that mechanisms related to reduced cAMP signaling may contribute to the present findings.
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Affiliation(s)
- Mehrnoush Zobeiri
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany.
| | - Rahul Chaudhary
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Maia Datunashvili
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Robert J Heuermann
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Feinberg School of Medicine, Northwestern University, 60611Chicago, USA
| | - Annika Lüttjohann
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Venu Narayanan
- Department of Neurology and Institute of Translational Neurology, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Sabine Balfanz
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Patrick Meuth
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Dane M Chetkovich
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Feinberg School of Medicine, Northwestern University, 60611Chicago, USA
| | - Hans-Christian Pape
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Arnd Baumann
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | | | - Thomas Budde
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany.
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14
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15
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Orts-Del'Immagine A, Pugh JR. Activity-dependent plasticity of presynaptic GABA B receptors at parallel fiber synapses. Synapse 2018; 72:e22027. [PMID: 29360168 DOI: 10.1002/syn.22027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/05/2018] [Accepted: 01/21/2018] [Indexed: 01/10/2023]
Abstract
Parallel fiber synapses in the cerebellum express a wide range of presynaptic receptors. However, presynaptic receptor expression at individual parallel fiber synapses is quite heterogeneous, suggesting physiological mechanisms regulate presynaptic receptor expression. We investigated changes in presynaptic GABAB receptors at parallel fiber-stellate cell synapses in acute cerebellar slices from juvenile mice. GABAB receptor-mediated inhibition of excitatory postsynaptic currents (EPSCs) is remarkably diverse at these synapses, with transmitter release at some synapses inhibited by >50% and little or no inhibition at others. GABAB receptor-mediated inhibition was significantly reduced following 4 Hz parallel fiber stimulation but not after stimulation at other frequencies. The reduction in GABAB receptor-mediated inhibition was replicated by bath application of forskolin and blocked by application of a PKA inhibitor, suggesting activation of adenylyl cyclase and PKA are required. Immunolabeling for an extracellular domain of the GABAB2 subunit revealed reduced surface expression in the molecular layer after exposure to forskolin. GABAB receptor-mediated inhibition of action potential evoked calcium transients in parallel fiber varicosities was also reduced following bath application of forskolin, confirming presynaptic receptors are responsible for the reduced EPSC inhibition. These data demonstrate that presynaptic GABAB receptor expression can be a plastic property of synapses, which may compliment other forms of synaptic plasticity. This opens the door to novel forms of receptor plasticity previously confined primarily to postsynaptic receptors.
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Affiliation(s)
- Adeline Orts-Del'Immagine
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229
| | - Jason R Pugh
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229
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16
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Dai M, Wang W, Wang P, Iqbal MZ, Annabi N, Amin N. Realization of tunable artificial synapse and memory based on amorphous oxide semiconductor transistor. Sci Rep 2017; 7:10997. [PMID: 28887449 PMCID: PMC5591224 DOI: 10.1038/s41598-017-04641-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/15/2017] [Indexed: 11/10/2022] Open
Abstract
Recently, advanced designs and materials emerge to study biologically inspired neuromorphic circuit, such as oxide semiconductor devices. The existence of mobile ions in the oxide semiconductors could be somewhat regarded to be similar with the case of the ions movements among the neurons and synapses in the brain. Most of the previous studies focus on the spike time, pulse number and material species: however, a quantitative modeling is still needed to study the voltage dependence of the relaxation process of synaptic devices. Here, the gate pulse stimulated currents of oxide semiconductor devices have been employed to mimic and investigate artificial synapses functions. The modeling for relaxation process of important synaptic behaviors, excitatory post-synaptic current (EPSC), has been updated as a stretched-exponential function with voltage factors in a more quantitative way. This quantitative modeling investigation of representative synaptic transmission bias impacts would help to better simulate, realize and thus control neuromorphic computing.
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Affiliation(s)
- Mingzhi Dai
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
| | - Weiliang Wang
- Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
- Institute of Circuits and Systems, Ningbo University, Ningbo, 315211, China
| | - Pengjun Wang
- Institute of Circuits and Systems, Ningbo University, Ningbo, 315211, China
- College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou, 325035, China
| | - Muhammad Zahir Iqbal
- GIK Institute of Engineering Sciences & Technology, Topi 23640, Khyber, Pakhtunkhwa, Pakistan
| | - Nasim Annabi
- Department of Chemical Engineering, Northeastern University, Boston, USA
| | - Nasir Amin
- Government College University Faisalabad, Faisalabad, Pakistan
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17
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CDYL suppresses epileptogenesis in mice through repression of axonal Nav1.6 sodium channel expression. Nat Commun 2017; 8:355. [PMID: 28842554 PMCID: PMC5572458 DOI: 10.1038/s41467-017-00368-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 06/25/2017] [Indexed: 12/27/2022] Open
Abstract
Impairment of intrinsic plasticity is involved in a range of neurological disorders such as epilepsy. However, how intrinsic excitability is regulated is still not fully understood. Here we report that the epigenetic factor Chromodomain Y-like (CDYL) protein is a critical regulator of the initiation and maintenance of intrinsic neuroplasticity by regulating voltage-gated ion channels in mouse brains. CDYL binds to a regulatory element in the intron region of SCN8A and mainly recruits H3K27me3 activity for transcriptional repression of the gene. Knockdown of CDYL in hippocampal neurons results in augmented Nav1.6 currents, lower neuronal threshold, and increased seizure susceptibility, whereas transgenic mice over-expressing CDYL exhibit higher neuronal threshold and are less prone to epileptogenesis. Finally, examination of human brain tissues reveals decreased CDYL and increased SCN8A in the temporal lobe epilepsy group. Together, our findings indicate CDYL is a critical player for experience-dependent gene regulation in controlling intrinsic excitability. Alterations in intrinsic plasticity are important in epilepsy. Here the authors show that the epigenetic factor CDYL regulates the gene expression of the voltage gated sodium channel, Nav1.6, which contributes to seizures in a rat model of epilepsy.
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18
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Abstract
Major depressive disorder (MDD) is a chronic and potentially life threatening illness that carries a staggering global burden. Characterized by depressed mood, MDD is often difficult to diagnose and treat owing to heterogeneity of syndrome and complex etiology. Contemporary antidepressant treatments are based on improved monoamine-based formulations from serendipitous discoveries made > 60 years ago. Novel antidepressant treatments are necessary, as roughly half of patients using available antidepressants do not see long-term remission of depressive symptoms. Current development of treatment options focuses on generating efficacious antidepressants, identifying depression-related neural substrates, and better understanding the pathophysiological mechanisms of depression. Recent insight into the brain's mesocorticolimbic circuitry from animal models of depression underscores the importance of ionic mechanisms in neuronal homeostasis and dysregulation, and substantial evidence highlights a potential role for ion channels in mediating depression-related excitability changes. In particular, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential regulators of neuronal excitability. In this review, we describe seminal research on HCN channels in the prefrontal cortex and hippocampus in stress and depression-related behaviors, and highlight substantial evidence within the ventral tegmental area supporting the development of novel therapeutics targeting HCN channels in MDD. We argue that methods targeting the activity of reward-related brain areas have significant potential as superior treatments for depression.
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Affiliation(s)
- Stacy M Ku
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Ming-Hu Han
- Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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19
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Han Y, Heuermann RJ, Lyman KA, Fisher D, Ismail QA, Chetkovich DM. HCN-channel dendritic targeting requires bipartite interaction with TRIP8b and regulates antidepressant-like behavioral effects. Mol Psychiatry 2017; 22:458-465. [PMID: 27400855 PMCID: PMC5233690 DOI: 10.1038/mp.2016.99] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/25/2016] [Accepted: 05/10/2016] [Indexed: 12/29/2022]
Abstract
Major depressive disorder (MDD) is a prevalent psychiatric condition with limited therapeutic options beyond monoaminergic therapies. Although effective in some individuals, many patients fail to respond adequately to existing treatments, and new pharmacologic targets are needed. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate excitability in neurons, and blocking HCN channel function has been proposed as a novel antidepressant strategy. However, systemic blockade of HCN channels produces cardiac effects that limit this approach. Knockout (KO) of the brain-specific HCN-channel auxiliary subunit tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) also produces antidepressant-like behavioral effects and suggests that inhibiting TRIP8b function could produce antidepressant-like effects without affecting the heart. We examined the structural basis of TRIP8b-mediated HCN-channel trafficking and its relationship with antidepressant-like behavior using a viral rescue approach in TRIP8b KO mice. We found that restoring TRIP8b to the hippocampus was sufficient to reverse the impaired HCN-channel trafficking and antidepressant-like behavioral effects caused by TRIP8b KO. Moreover, we found that hippocampal expression of a mutated version of TRIP8b further impaired HCN-channel trafficking and increased the antidepressant-like behavioral phenotype of TRIP8b KO mice. Thus, modulating the TRIP8b-HCN interaction bidirectionally influences channel trafficking and antidepressant-like behavior. Overall, our work suggests that small-molecule inhibitors of the interaction between TRIP8b and HCN should produce antidepressant-like behaviors and could represent a new paradigm for the treatment of MDD.
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Affiliation(s)
- Ye Han
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Robert J. Heuermann
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Kyle A. Lyman
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Daniel Fisher
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Quratul-Ain Ismail
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Dane M. Chetkovich
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
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20
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The Dendrites of CA2 and CA1 Pyramidal Neurons Differentially Regulate Information Flow in the Cortico-Hippocampal Circuit. J Neurosci 2017; 37:3276-3293. [PMID: 28213444 DOI: 10.1523/jneurosci.2219-16.2017] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/27/2016] [Accepted: 02/07/2017] [Indexed: 12/29/2022] Open
Abstract
The impact of a given neuronal pathway depends on the number of synapses it makes with its postsynaptic target, the strength of each individual synapse, and the integrative properties of the postsynaptic dendrites. Here we explore the cellular and synaptic mechanisms responsible for the differential excitatory drive from the entorhinal cortical pathway onto mouse CA2 compared with CA1 pyramidal neurons (PNs). Although both types of neurons receive direct input from entorhinal cortex onto their distal dendrites, these inputs produce a 5- to 6-fold larger EPSP at the soma of CA2 compared with CA1 PNs, which is sufficient to drive action potential output from CA2 but not CA1. Experimental and computational approaches reveal that dendritic propagation is more efficient in CA2 than CA1 as a result of differences in dendritic morphology and dendritic expression of the hyperpolarization-activated cation current (Ih). Furthermore, there are three times as many cortical inputs onto CA2 compared with CA1 PN distal dendrites. Using a computational model, we demonstrate that the differences in dendritic properties of CA2 compared with CA1 PNs are necessary to enable the CA2 PNs to generate their characteristically large EPSPs in response to their cortical inputs; in contrast, CA1 dendritic properties limit the size of the EPSPs they generate, even to a similar number of cortical inputs. Thus, the matching of dendritic integrative properties with the density of innervation is crucial for the differential processing of information from the direct cortical inputs by CA2 compared with CA1 PNs.SIGNIFICANCE STATEMENT Recent discoveries have shown that the long-neglected hippocampal CA2 region has distinct synaptic properties and plays a prominent role in social memory and schizophrenia. This study addresses the puzzling finding that the direct entorhinal cortical inputs to hippocampus, which target the very distal pyramidal neuron dendrites, provide an unusually strong excitatory drive at the soma of CA2 pyramidal neurons, with EPSPs that are 5-6 times larger than those in CA1 pyramidal neurons. We here elucidate synaptic and dendritic mechanisms that account quantitatively for the marked difference in EPSP size. Our findings further demonstrate the general importance of fine-tuning the integrative properties of neuronal dendrites to their density of synaptic innervation.
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21
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Huang Z, Li G, Aguado C, Lujan R, Shah MM. HCN1 channels reduce the rate of exocytosis from a subset of cortical synaptic terminals. Sci Rep 2017; 7:40257. [PMID: 28071723 PMCID: PMC5223132 DOI: 10.1038/srep40257] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/02/2016] [Indexed: 12/18/2022] Open
Abstract
The hyperpolarization-activated cyclic nucleotide-gated (HCN1) channels are predominantly located in pyramidal cell dendrites within the cortex. Recent evidence suggests these channels also exist pre-synaptically in a subset of synaptic terminals within the mature entorhinal cortex (EC). Inhibition of pre-synaptic HCN channels enhances miniature excitatory post-synaptic currents (mEPSCs) onto EC layer III pyramidal neurons, suggesting that these channels decrease the release of the neurotransmitter, glutamate. Thus, do pre-synaptic HCN channels alter the rate of synaptic vesicle exocytosis and thereby enhance neurotransmitter release? To address this, we imaged the release of FM1-43, a dye that is incorporated into synaptic vesicles, from EC synaptic terminals using two photon microscopy in slices obtained from forebrain specific HCN1 deficient mice, global HCN1 knockouts and their wildtype littermates. This coupled with electrophysiology and pharmacology showed that HCN1 channels restrict the rate of exocytosis from a subset of cortical synaptic terminals within the EC and in this way, constrain non-action potential-dependent and action potential-dependent spontaneous release as well as synchronous, evoked release. Since HCN1 channels also affect post-synaptic potential kinetics and integration, our results indicate that there are diverse ways by which HCN1 channels influence synaptic strength and plasticity.
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Affiliation(s)
- Zhuo Huang
- UCL School of Pharmacy, University College London, London, WC1N 1AX, UK
| | - Gengyu Li
- UCL School of Pharmacy, University College London, London, WC1N 1AX, UK
| | - Carolina Aguado
- Departamento de Ciencias Medicas, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Rafael Lujan
- Departamento de Ciencias Medicas, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Mala M Shah
- UCL School of Pharmacy, University College London, London, WC1N 1AX, UK
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22
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Howell RD, Pugh JR. Biphasic modulation of parallel fibre synaptic transmission by co-activation of presynaptic GABAA and GABAB receptors in mice. J Physiol 2016; 594:3651-66. [PMID: 27061582 DOI: 10.1113/jp272124] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/30/2016] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Many excitatory synapses co-express presynaptic GABAA and GABAB receptors, despite their opposing actions on synaptic transmission. It is still unclear how co-activation of these receptors modulates synapse function. We measured presynaptic GABA receptor function at parallel fibre synapses onto stellate cells in the cerebellum using whole-cell patch-clamp recording and photolytic uncaging of RuBi-GABA. Activation of presynaptic GABA receptors results in a transient (∼100 ms) enhancement of synaptic transmission (mediated by GABAA receptors) followed by a long lasting (>500 ms) inhibition of transmission (mediated by GABAB receptors). When activated just prior to high-frequency trains of stimulation, presynaptic GABAA and GABAB receptors work together to reduce short-term facilitation/enhance depression, altering the filtering properties of synaptic transmission. Inhibition of synaptic transmission by GABAB receptors is more sensitive to GABA than enhancement by GABAA receptors, suggesting GABAB receptors may be activated by ambient GABA or release from greater distances. ABSTRACT GABAA and GABAB receptors are co-expressed at many presynaptic terminals in the central nervous system. Previous studies have shown that GABAA receptors typically enhance vesicle release while GABAB receptors inhibit release. However, it is not clear how the competing actions of these receptors modulate synaptic transmission when co-activated, as is likely in vivo. We investigated this question at parallel fibre synapses in the cerebellum, which co-express presynaptic GABAA and GABAB receptors. In acute slices from C57BL/6 mice, we find that co-activation of presynaptic GABA receptors by photolytic uncaging of RuBi-GABA has a biphasic effect on EPSC amplitudes recorded from stellate cells. Synchronous and asynchronous EPSCs evoked within ∼100 ms of GABA uncaging were increased, while EPSCs evoked ∼300-600 ms after GABA uncaging were reduced compared to interleaved control sweeps. We confirmed these effects are presynaptic by measuring the paired-pulse ratio, variance of EPSC amplitudes, and response probability. During trains of high-frequency stimulation GABAA and GABAB receptors work together (rather than oppose one another) to reduce short-term facilitation when GABA is uncaged just prior to the onset of stimulation. We also find that GABAB receptor-mediated inhibition can be elicited by lower GABA concentrations than GABAA receptor-mediated enhancement of EPSCs, suggesting GABAB receptors may be selectively activated by ambient GABA or release from more distance synapses. These data suggest that GABA, acting through both presynaptic GABAA and GABAB receptors, modulate the amplitude and short-term plasticity of excitatory synapses, a result not possible from activation of either receptor type alone.
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Affiliation(s)
- Rebecca D Howell
- University of Texas Health Science Center at San Antonio, Department of Physiology, San Antonio, TX 78229, USA
| | - Jason R Pugh
- University of Texas Health Science Center at San Antonio, Department of Physiology, San Antonio, TX 78229, USA
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23
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Brennan GP, Baram TZ, Poolos NP. Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channels in Epilepsy. Cold Spring Harb Perspect Med 2016; 6:a022384. [PMID: 26931806 DOI: 10.1101/cshperspect.a022384] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Epilepsy is a common brain disorder characterized by the occurrence of spontaneous seizures. These bursts of synchronous firing arise from abnormalities of neuronal networks. Excitability of individual neurons and neuronal networks is largely governed by ion channels and, indeed, abnormalities of a number of ion channels resulting from mutations or aberrant expression and trafficking underlie several types of epilepsy. Here, we focus on the hyperpolarization-activated cyclic nucleotide-gated ion (HCN) channels that conduct Ih current. This conductance plays complex and diverse roles in the regulation of neuronal and network excitability. We describe the normal function of HCN channels and discuss how aberrant expression, assembly, trafficking, and posttranslational modifications contribute to experimental and human epilepsy.
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Affiliation(s)
- Gary P Brennan
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475
| | - Tallie Z Baram
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475 Departments of Anatomy/Neurobiology and Neurology, University of California-Irvine, Irvine, California 92697-4475
| | - Nicholas P Poolos
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, Washington 98104
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24
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Kopp-Scheinpflug C, Pigott BM, Forsythe ID. Nitric oxide selectively suppresses IH currents mediated by HCN1-containing channels. J Physiol 2015; 593:1685-700. [PMID: 25605440 PMCID: PMC4386966 DOI: 10.1113/jphysiol.2014.282194] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 01/16/2015] [Indexed: 12/12/2022] Open
Abstract
Hyperpolarization-activated non-specific cation-permeable channels (HCN) mediate I(H) currents, which are modulated by cGMP and cAMP and by nitric oxide (NO) signalling. Channel properties depend upon subunit composition (HCN1-4 and accessory subunits) as demonstrated in expression systems, but physiological relevance requires investigation in native neurons with intact intracellular signalling. Here we use the superior olivary complex (SOC), which exhibits a distinctive pattern of HCN1 and HCN2 expression, to investigate NO modulation of the respective I(H) currents, and compare properties in wild-type and HCN1 knockout mice. The medial nucleus of the trapezoid body (MNTB) expresses HCN2 subunits exclusively, and sends inhibitory projections to the medial and lateral superior olives (MSO, LSO) and the superior paraolivary nucleus (SPN). In contrast to the MNTB, these target nuclei possess an I(H) with fast kinetics, and they express HCN1 subunits. NO is generated in the SOC following synaptic activity and here we show that NO selectively suppresses HCN1, while enhancing IH mediated by HCN2 subunits. NO hyperpolarizes the half-activation of HCN1-mediated currents and slows the kinetics of native IH currents in the MSO, LSO and SPN. This modulation was independent of cGMP and absent in transgenic mice lacking HCN1. Independently, NO signalling depolarizes the half-activation of HCN2-mediated I(H) currents in a cGMP-dependent manner. Thus, NO selectively suppresses fast HCN1-mediated I(H) and facilitates a slow HCN2-mediated I(H) , so generating a spectrum of modulation, dependent on the local expression of HCN1 and/or HCN2.
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Affiliation(s)
- Cornelia Kopp-Scheinpflug
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Großhadernerstr. 282152, Planegg-Martinsried, Germany
| | - Beatrice M Pigott
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, LE1 9HN, UK
| | - Ian D Forsythe
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, LE1 9HN, UK
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25
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Martinello K, Huang Z, Lujan R, Tran B, Watanabe M, Cooper EC, Brown DA, Shah MM. Cholinergic afferent stimulation induces axonal function plasticity in adult hippocampal granule cells. Neuron 2015; 85:346-63. [PMID: 25578363 PMCID: PMC4306544 DOI: 10.1016/j.neuron.2014.12.030] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2014] [Indexed: 01/25/2023]
Abstract
Acetylcholine critically influences hippocampal-dependent learning. Cholinergic fibers innervate hippocampal neuron axons, dendrites, and somata. The effects of acetylcholine on axonal information processing, though, remain unknown. By stimulating cholinergic fibers and making electrophysiological recordings from hippocampal dentate gyrus granule cells, we show that synaptically released acetylcholine preferentially lowered the action potential threshold, enhancing intrinsic excitability and synaptic potential-spike coupling. These effects persisted for at least 30 min after the stimulation paradigm and were due to muscarinic receptor activation. This caused sustained elevation of axonal intracellular Ca2+ via T-type Ca2+ channels, as indicated by two-photon imaging. The enhanced Ca2+ levels inhibited an axonal KV7/M current, decreasing the spike threshold. In support, immunohistochemistry revealed muscarinic M1 receptor, CaV3.2, and KV7.2/7.3 subunit localization in granule cell axons. Since alterations in axonal signaling affect neuronal firing patterns and neurotransmitter release, this is an unreported cellular mechanism by which acetylcholine might, at least partly, enhance cognitive processing. Cholinergic fiber stimulation caused a persistent reduction in the spike threshold Post-synaptic muscarinic receptor activation enhanced axonal CaV3.2 channel activity The sustained Ca2+ entry inhibited axonal KV7 channels, lowering the spike threshold The lower spike threshold increased the propensity for action potential generation
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Affiliation(s)
| | - Zhuo Huang
- UCL School of Pharmacy, University College London, London, WC1N 1AX, UK
| | - Rafael Lujan
- Departamento de Ciencias Medicas, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Baouyen Tran
- Neurology and Neuroscience, Baylor College of Medicine, TX 77030, USA
| | - Masahiko Watanabe
- Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Edward C Cooper
- Neurology and Neuroscience, Baylor College of Medicine, TX 77030, USA
| | - David A Brown
- Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Mala M Shah
- UCL School of Pharmacy, University College London, London, WC1N 1AX, UK.
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26
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Pan Y, Laird JG, Yamaguchi DM, Baker SA. A di-arginine ER retention signal regulates trafficking of HCN1 channels from the early secretory pathway to the plasma membrane. Cell Mol Life Sci 2014; 72:833-43. [PMID: 25142030 PMCID: PMC4309907 DOI: 10.1007/s00018-014-1705-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/14/2014] [Accepted: 08/12/2014] [Indexed: 12/25/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels carry Ih, which contributes to neuronal excitability and signal transmission in the nervous system. Controlling the trafficking of HCN1 is an important aspect of its regulation, yet the details of this process are poorly understood. Here, we investigated how the C-terminus of HCN1 regulates trafficking by testing for its ability to redirect the localization of a non-targeted reporter in transgenic Xenopus laevis photoreceptors. We found that HCN1 contains an ER localization signal and through a series of deletion constructs, identified the responsible di-arginine ER retention signal. This signal is located in the intrinsically disordered region of the C-terminus of HCN1. To test the function of the ER retention signal in intact channels, we expressed wild type and mutant HCN1 in HEK293 cells and found this signal negatively regulates surface expression of HCN1. In summary, we report a new mode of regulating HCN1 trafficking: through the use of a di-arginine ER retention signal that monitors processing of the channel in the early secretory pathway.
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Affiliation(s)
- Yuan Pan
- Department of Biochemistry, Carver College of Medicine, University of Iowa, 51 Newton Road, Biochemistry, 4-712 BSB, Iowa City, IA, 52242, USA
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27
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Shah MM. Cortical HCN channels: function, trafficking and plasticity. J Physiol 2014; 592:2711-9. [PMID: 24756635 PMCID: PMC4104471 DOI: 10.1113/jphysiol.2013.270058] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 04/15/2014] [Indexed: 12/26/2022] Open
Abstract
The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels belong to the superfamily of voltage-gated potassium ion channels. They are, however, activated by hyperpolarizing potentials and are permeable to cations. Four HCN subunits have been cloned, of which HCN1 and HCN2 subunits are predominantly expressed in the cortex. These subunits are principally located in pyramidal cell dendrites, although they are also found at lower concentrations in the somata of pyramidal neurons as well as other neuron subtypes. HCN channels are actively trafficked to dendrites by binding to the chaperone protein TRIP8b. Somato-dendritic HCN channels in pyramidal neurons modulate spike firing and synaptic potential integration by influencing the membrane resistance and resting membrane potential. Intriguingly, HCN channels are present in certain cortical axons and synaptic terminals too. Here, they regulate synaptic transmission but the underlying mechanisms appear to vary considerably amongst different synaptic terminals. In conclusion, HCN channels are expressed in multiple neuronal subcellular compartments in the cortex, where they have a diverse and complex effect on neuronal excitability.
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Affiliation(s)
- Mala M Shah
- Department of Pharmacology, UCL School of Pharmacy, London, UK
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28
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Pan Y, Bhattarai S, Modestou M, Drack AV, Chetkovich DM, Baker SA. TRIP8b is required for maximal expression of HCN1 in the mouse retina. PLoS One 2014; 9:e85850. [PMID: 24409334 PMCID: PMC3883711 DOI: 10.1371/journal.pone.0085850] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/31/2013] [Indexed: 01/04/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are cation-selective channels present in retina, brain and heart. The activity of HCN channels contributes to signal integration, cell excitability and pacemaker activity. HCN1 channels expressed in photoreceptors participate in keeping light responses transient and are required for normal mesopic vision. The subcellular localization of HCN1 varies among cell types. In photoreceptors HCN1 is concentrated in the inner segments while in other retinal neurons, HCN1 is evenly distributed though the cell. This is in contrast to hippocampal neurons where HCN1 is concentrated in a subset of dendrites. A key regulator of HCN1 trafficking and activity is tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b). Multiple splice isoforms of TRIP8b are expressed throughout the brain and can differentially regulate the surface expression and activity of HCN1. The purpose of the present study was to determine which isoforms of TRIP8b are expressed in the retina and to test if loss of TRIP8b alters HCN1 expression or trafficking. We found that TRIP8b colocalizes with HCN1 in multiple retina neurons and all major splice isoforms of TRIP8b are expressed in the retina. Photoreceptors express three different isoforms. In TRIP8b knockout mice, the ability of HCN1 to traffic to the surface of retinal neurons is unaffected. However, there is a large decrease in the total amount of HCN1. We conclude that TRIP8b in the retina is needed to achieve maximal expression of HCN1.
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Affiliation(s)
- Yuan Pan
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Sajag Bhattarai
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Modestos Modestou
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Arlene V. Drack
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Dane M. Chetkovich
- The Ken & Ruth Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Sheila A. Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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29
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Brager DH, Lewis AS, Chetkovich DM, Johnston D. Short- and long-term plasticity in CA1 neurons from mice lacking h-channel auxiliary subunit TRIP8b. J Neurophysiol 2013; 110:2350-7. [PMID: 23966674 PMCID: PMC3841871 DOI: 10.1152/jn.00218.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 08/17/2013] [Indexed: 01/11/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated nonselective cation channels (HCN or h-channels) are important regulators of neuronal physiology contributing to passive membrane properties, such as resting membrane potential and input resistance (R(N)), and to intrinsic oscillatory activity and synaptic integration. The correct membrane targeting of h-channels is regulated in part by the auxiliary h-channel protein TRIP8b. The genetic deletion of TRIP8b results in a loss of functional h-channels, which affects the postsynaptic integrative properties of neurons. We investigated the impact of TRIP8b deletion on long-term potentiation (LTP) at the two major excitatory inputs to CA1 pyramidal neurons: Schaffer collateral (SC) and perforant path (PP). We found that SC LTP was not significantly different between neurons from wild-type and TRIP8b-knockout mice. There was, however, significantly more short-term potentiation in knockout neurons. We also found that the persistent increase in h-current (I(h)) that normally occurs after LTP induction was absent in knockout neurons. The lack of I(h) plasticity was not restricted to activity-dependent induction, because the depletion of intracellular calcium stores also failed to produce the expected increase in I(h). Interestingly, pairing of SC and PP inputs resulted in a form of LTP in knockout neurons that did not occur in wild-type neurons. These results suggest that the physiological impact of TRIP8b deletion is not restricted to the integrative properties of neurons but also includes both synaptic and intrinsic plasticity.
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Affiliation(s)
- Darrin H Brager
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas
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30
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Abstract
Photoreceptors are exquisitely adapted to transform light stimuli into electrical signals that modulate neurotransmitter release. These cells are organized into several compartments including the unique outer segment (OS). Its whole function is to absorb light and transduce this signal into a change of membrane potential. Another compartment is the inner segment where much of metabolism and regulation of membrane potential takes place and that connects the OS and synapse. The synapse is the compartment where changes in membrane potentials are relayed to other neurons in the retina via release of neurotransmitter. The composition of the plasma membrane surrounding these compartments varies to accommodate their specific functions. In this chapter, we discuss the organization of the plasma membrane emphasizing the protein composition of each region as it relates to visual signaling. We also point out examples where mutations in these proteins cause visual impairment.
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Affiliation(s)
- Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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