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Zhang Z, Luo X, Jiang L, Wu H, Tan Z. How do HCN channels play a part in Alzheimer's and Parkinson's disease? Ageing Res Rev 2024; 100:102436. [PMID: 39047878 DOI: 10.1016/j.arr.2024.102436] [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: 04/16/2024] [Revised: 07/08/2024] [Accepted: 07/18/2024] [Indexed: 07/27/2024]
Abstract
Neurodegenerative diseases like Alzheimer's and Parkinson's disease (AD and PD) are well-known, yet their underlying causes remain unclear. Recent studies have suggested that disruption of ion channels contribute to their pathogenesis. Among these channels, the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, encoded by HCN1-4 genes, are of particular interest due to their role in generating hyperpolarization-activated current (Ih), which is crucial in various neural activities impacting memory and motor functions. A growing body of evidence underscores the pivotal role of HCN in Aβ generation, glial cell function, and ischemia-induced dementia; while HCN is expressed in various regions of the basal ganglia, modulating their functions and influencing motor disorders in PD; neuroinflammation triggered by microglial activation represents a shared pathological mechanism in both AD and PD, in which HCN also plays a significant part. This review delves into the neuronal functions governed by HCN, its roles in the aforementioned pathogenesis, its expression patterns in AD and PD, and discusses potential therapeutic drugs targeting HCN for the treatment of these diseases, aiming to offer a novel perspective and inspire future research endeavors.
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Affiliation(s)
- Zhuo Zhang
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410078, PR China; Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, PR China; National Clinical Research Center for Geriatric Disorders, Changsha 410008, PR China; Changsha Taihe Hospital, Changsha 410000, PR China; Hunan Key Laboratory for Bioanalysis of Complex Matrix Samples, Changsha 410205, PR China
| | - Xin Luo
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410078, PR China; Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, PR China; National Clinical Research Center for Geriatric Disorders, Changsha 410008, PR China; Changsha Taihe Hospital, Changsha 410000, PR China; Hunan Key Laboratory for Bioanalysis of Complex Matrix Samples, Changsha 410205, PR China
| | - Liping Jiang
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410078, PR China; Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, PR China; National Clinical Research Center for Geriatric Disorders, Changsha 410008, PR China; Department of Physiology, Basic Medical School, Hengyang Medical College, The Neuroscience Institute, University of South China, Hengyang 421001, PR China; Changsha Taihe Hospital, Changsha 410000, PR China; Hunan Key Laboratory for Bioanalysis of Complex Matrix Samples, Changsha 410205, PR China
| | - Huilan Wu
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410078, PR China; Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, PR China; National Clinical Research Center for Geriatric Disorders, Changsha 410008, PR China; Changsha Taihe Hospital, Changsha 410000, PR China; Hunan Key Laboratory for Bioanalysis of Complex Matrix Samples, Changsha 410205, PR China
| | - Zhirong Tan
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Hunan Key Laboratory of Pharmacogenetics, Institute of Clinical Pharmacology, Central South University, Changsha 410078, PR China; Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha 410078, PR China; National Clinical Research Center for Geriatric Disorders, Changsha 410008, PR China; Changsha Taihe Hospital, Changsha 410000, PR China; Hunan Key Laboratory for Bioanalysis of Complex Matrix Samples, Changsha 410205, PR China.
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Harde E, Hierl M, Weber M, Waiz D, Wyler R, Wach JY, Haab R, Gundlfinger A, He W, Schnider P, Paina M, Rolland JF, Greiter-Wilke A, Gasser R, Reutlinger M, Dupont A, Roberts S, O'Connor EC, Bartels B, Hall BJ. Selective and brain-penetrant HCN1 inhibitors reveal links between synaptic integration, cortical function, and working memory. Cell Chem Biol 2024; 31:577-592.e23. [PMID: 38042151 DOI: 10.1016/j.chembiol.2023.11.004] [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: 06/29/2023] [Revised: 09/28/2023] [Accepted: 11/07/2023] [Indexed: 12/04/2023]
Abstract
Hyperpolarization-activated and cyclic-nucleotide-gated 1 (HCN1) ion channels are proposed to be critical for cognitive function through regulation of synaptic integration. However, resolving the precise role of HCN1 in neurophysiology and exploiting its therapeutic potential has been hampered by minimally selective antagonists with poor potency and limited in vivo efficiency. Using automated electrophysiology in a small-molecule library screen and chemical optimization, we identified a primary carboxamide series of potent and selective HCN1 inhibitors with a distinct mode of action. In cognition-relevant brain circuits, selective inhibition of native HCN1 produced on-target effects, including enhanced excitatory postsynaptic potential summation, while administration of a selective HCN1 inhibitor to rats recovered decrement working memory. Unlike prior non-selective HCN antagonists, selective HCN1 inhibition did not alter cardiac physiology in human atrial cardiomyocytes or in rats. Collectively, selective HCN1 inhibitors described herein unmask HCN1 as a potential target for the treatment of cognitive dysfunction in brain disorders.
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Affiliation(s)
- Eva Harde
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
| | - Markus Hierl
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Michael Weber
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - David Waiz
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Roger Wyler
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Jean-Yves Wach
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Rachel Haab
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Anja Gundlfinger
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Weiping He
- WuXi AppTec (Wuhan) Co., Ltd, 666 Gaoxin Road, Wuhan East Lake High-Tech Development Zone, Wuhan, Huibei, China
| | - Patrick Schnider
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | | | | | - Andrea Greiter-Wilke
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Rodolfo Gasser
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Michael Reutlinger
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Amanda Dupont
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Sonia Roberts
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Eoin C O'Connor
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
| | - Björn Bartels
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
| | - Benjamin J Hall
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
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Kim D, Roh H, Lee HM, Kim SJ, Im M. Localization of hyperpolarization-activated cyclic nucleotide-gated channels in the vertebrate retinas across species and their physiological roles. Front Neuroanat 2024; 18:1385932. [PMID: 38562955 PMCID: PMC10982330 DOI: 10.3389/fnana.2024.1385932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 03/06/2024] [Indexed: 04/04/2024] Open
Abstract
Transmembrane proteins known as hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control the movement of Na+ and K+ ions across cellular membranes. HCN channels are known to be involved in crucial physiological functions in regulating neuronal excitability and rhythmicity, and pacemaker activity in the heart. Although HCN channels have been relatively well investigated in the brain, their distribution and function in the retina have received less attention, remaining their physiological roles to be comprehensively understood. Also, because recent studies reported HCN channels have been somewhat linked with the dysfunction of photoreceptors which are affected by retinal diseases, investigating HCN channels in the retina may offer valuable insights into disease mechanisms and potentially contribute to identifying novel therapeutic targets for retinal degenerative disorders. This paper endeavors to summarize the existing literature on the distribution and function of HCN channels reported in the vertebrate retinas of various species and discuss the potential implications for the treatment of retinal diseases. Then, we recapitulate current knowledge regarding the function and regulation of HCN channels, as well as their relevance to various neurological disorders.
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Affiliation(s)
- Daniel Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Department of Biomedical Sciences, College of Medicine, Seoul National University (SNU), Seoul, Republic of Korea
| | - Hyeonhee Roh
- School of Electrical Engineering, College of Engineering, Korea University, Seoul, Republic of Korea
| | - Hyung-Min Lee
- School of Electrical Engineering, College of Engineering, Korea University, Seoul, Republic of Korea
| | - Sang Jeong Kim
- Department of Biomedical Sciences, College of Medicine, Seoul National University (SNU), Seoul, Republic of Korea
| | - Maesoon Im
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science & Technology (UST), Seoul, Republic of Korea
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul, Republic of Korea
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Zhang H, Graham V, Nepliouev I, Stiber JA, Rosenberg P. STIM1 interacts with HCN4 channels to coordinate diastolic depolarization in the mouse Sinoatrial node. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.03.539287. [PMID: 37205552 PMCID: PMC10187156 DOI: 10.1101/2023.05.03.539287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Cardiomyocytes in the sinoatrial node (SAN) are specialized to undergo spontaneous diastolic depolarization (DD) to create action potentials (AP) that serve as the origin of the heartbeat. Two cellular clocks govern DD: the membrane clock where ion channels contribute ionic conductance to create DD and the Ca 2+ clock where rhythmic Ca 2+ release from sarcoplasmic reticulum (SR) during diastole contributes pacemaking. How the membrane and Ca 2+ clocks interact to synchronize and drive DD is not well understood. Here, we identified stromal interaction molecule 1 (STIM1), the activator of store operated Ca 2+ entry (SOCE), in the P-cell cardiomyocytes of the SAN. Functional studies from STIM1 KO mice reveal dramatic changes in properties of AP and DD. Mechanistically, we show that STIM1 regulates the funny currents and HCN4 channels that are required to initiate DD and maintain sinus rhythm in mice. Taken together, our studies suggest that STIM1 acts as a sensor for both the Ca 2+ and membrane clocks for mouse SAN for cardiac pacemaking.
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Majgaard J, Skov FG, Kim S, Hjortdal VE, Boedtkjer DMB. Positive chronotropic action of HCN channel antagonism in human collecting lymphatic vessels. Physiol Rep 2022; 10:e15401. [PMID: 35980021 PMCID: PMC9387113 DOI: 10.14814/phy2.15401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 06/16/2022] [Accepted: 07/09/2022] [Indexed: 06/15/2023] Open
Abstract
Spontaneous action potentials precede phasic contractile activity in human collecting lymphatic vessels. In this study, we investigated the expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in human collecting lymphatics and by pharmacological inhibition ex vivo tested their potential role in controlling contractile function. Spontaneous and agonist-evoked tension changes of isolated thoracic duct and mesenteric lymphatic vessels-obtained from surgical patients with informed consent-were investigated by isometric myography, and ivabradine, ZD7288 or cesium were used to inhibit HCN. Analysis of HCN isoforms by RT-PCR and immunofluorescence revealed HCN2 to be the predominantly expressed mRNA isoform in human thoracic duct and mesenteric lymphatic vessels and HCN2-immunoreactivity confirmed protein expression in both vessel types. However, in functional experiments ex vivo the HCN inhibitors ivabradine, ZD7288, and cesium failed to lower contraction frequency: conversely, all three antagonists induced a positive chronotropic effect with concurrent negative inotropic action, though these effects first occurred at concentrations regarded as supramaximal for HCN inhibition. Based on these results, we conclude that human collecting vessels express HCN channel proteins but under the ex vivo experimental conditions described here HCN channels have little involvement in regulating contraction frequency in human collecting lymphatic vessels. Furthermore, HCN antagonists can produce concentration-dependent positive chronotropic and negative inotropic effects, which are apparently unrelated to HCN antagonism.
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Affiliation(s)
- Jens Majgaard
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | | | - Sukhan Kim
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Vibeke Elisabeth Hjortdal
- Department of Clinical MedicineAarhus UniversityAarhusDenmark
- Department of Cardiothoracic and Vascular SurgeryAarhus University HospitalAarhusDenmark
| | - Donna M. B. Boedtkjer
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Department of Clinical MedicineAarhus UniversityAarhusDenmark
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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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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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Loss of HCN2 in Dorsal Hippocampus of Young Adult Mice Induces Specific Apoptosis of the CA1 Pyramidal Neuron Layer. Int J Mol Sci 2021; 22:ijms22136699. [PMID: 34206649 PMCID: PMC8269412 DOI: 10.3390/ijms22136699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/08/2021] [Accepted: 06/18/2021] [Indexed: 11/20/2022] Open
Abstract
Neurons inevitably rely on a proper repertoire and distribution of membrane-bound ion-conducting channels. Among these proteins, the family of hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels possesses unique properties giving rise to the corresponding Ih-current that contributes to various aspects of neural signaling. In mammals, four genes (hcn1-4) encode subunits of HCN channels. These subunits can assemble as hetero- or homotetrameric ion-conducting channels. In order to elaborate on the specific role of the HCN2 subunit in shaping electrical properties of neurons, we applied an Adeno-associated virus (AAV)-mediated, RNAi-based knock-down strategy of hcn2 gene expression both in vitro and in vivo. Electrophysiological measurements showed that HCN2 subunit knock-down resulted in specific yet anticipated changes in Ih-current properties in primary hippocampal neurons and, in addition, corroborated that the HCN2 subunit participates in postsynaptic signal integration. To further address the role of the HCN2 subunit in vivo, we injected recombinant (r)AAVs into the dorsal hippocampus of young adult male mice. Behavioral and biochemical analyses were conducted to assess the contribution of HCN2-containing channels in shaping hippocampal network properties. Surprisingly, knock-down of hcn2 expression resulted in a severe degeneration of the CA1 pyramidal cell layer, which did not occur in mice injected with control rAAV constructs. This finding might pinpoint to a vital and yet unknown contribution of HCN2 channels in establishing or maintaining the proper function of CA1 pyramidal neurons of the dorsal hippocampus.
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Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
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Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
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11
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Importance of evaluating protein glycosylation in pluripotent stem cell-derived cardiomyocytes for research and clinical applications. Pflugers Arch 2021; 473:1041-1059. [PMID: 33830329 PMCID: PMC8245383 DOI: 10.1007/s00424-021-02554-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 03/01/2021] [Accepted: 03/06/2021] [Indexed: 01/21/2023]
Abstract
Proper protein glycosylation is critical to normal cardiomyocyte physiology. Aberrant glycosylation can alter protein localization, structure, drug interactions, and cellular function. The in vitro differentiation of human pluripotent stem cells into cardiomyocytes (hPSC-CM) has become increasingly important to the study of protein function and to the fields of cardiac disease modeling, drug testing, drug discovery, and regenerative medicine. Here, we offer our perspective on the importance of protein glycosylation in hPSC-CM. Protein glycosylation is dynamic in hPSC-CM, but the timing and extent of glycosylation are still poorly defined. We provide new data highlighting how observed changes in hPSC-CM glycosylation may be caused by underlying differences in the protein or transcript abundance of enzymes involved in building and trimming the glycan structures or glycoprotein gene products. We also provide evidence that alternative splicing results in altered sites of glycosylation within the protein sequence. Our findings suggest the need to precisely define protein glycosylation events that may have a critical impact on the function and maturation state of hPSC-CM. Finally, we provide an overview of analytical strategies available for studying protein glycosylation and identify opportunities for the development of new bioinformatic approaches to integrate diverse protein glycosylation data types. We predict that these tools will promote the accurate assessment of protein glycosylation in future studies of hPSC-CM that will ultimately be of significant experimental and clinical benefit.
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12
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Concepcion FA, Khan MN, Ju Wang JD, Wei AD, Ojemann JG, Ko AL, Shi Y, Eng JK, Ramirez JM, Poolos NP. HCN Channel Phosphorylation Sites Mapped by Mass Spectrometry in Human Epilepsy Patients and in an Animal Model of Temporal Lobe Epilepsy. Neuroscience 2021; 460:13-30. [PMID: 33571596 DOI: 10.1016/j.neuroscience.2021.01.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/07/2021] [Accepted: 01/26/2021] [Indexed: 10/22/2022]
Abstract
Because hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels modulate the excitability of cortical and hippocampal principal neurons, these channels play a key role in the hyperexcitability that occurs during the development of epilepsy after a brain insult, or epileptogenesis. In epileptic rats generated by pilocarpine-induced status epilepticus, HCN channel activity is downregulated by two main mechanisms: a hyperpolarizing shift in gating and a decrease in amplitude of the current mediated by HCN channels, Ih. Because these mechanisms are modulated by various phosphorylation signaling pathways, we hypothesized that phosphorylation changes occur at individual HCN channel amino acid residues (phosphosites) during epileptogenesis. We collected CA1 hippocampal tissue from male Sprague Dawley rats made epileptic by pilocarpine-induced status epilepticus, and age-matched naïve controls. We also included resected human brain tissue containing epileptogenic zones (EZs) where seizures arise for comparison to our chronically epileptic rats. After enrichment for HCN1 and HCN2 isoforms by immunoprecipitation and trypsin in-gel digestion, the samples were analyzed by mass spectrometry. We identified numerous phosphosites from HCN1 and HCN2 channels, representing a novel survey of phosphorylation sites within HCN channels. We found high levels of HCN channel phosphosite homology between humans and rats. We also identified a novel HCN1 channel phosphosite S791, which underwent significantly increased phosphorylation during the chronic epilepsy stage. Heterologous expression of a phosphomimetic mutant, S791D, replicated a hyperpolarizing shift in Ih gating seen in neurons from chronically epileptic rats. These results show that HCN1 channel phosphorylation is altered in epilepsy and may be of pathogenic importance.
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Affiliation(s)
- F A Concepcion
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, WA, United States
| | - M N Khan
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, WA, United States
| | - J-D Ju Wang
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, WA, United States
| | - A D Wei
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, WA, United States
| | - J G Ojemann
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, WA, United States; Department of Neurological Surgery, University of Washington, Seattle, WA, United States
| | - A L Ko
- Department of Neurological Surgery, University of Washington, Seattle, WA, United States
| | - Y Shi
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, United States
| | - J K Eng
- Proteomics Resource, University of Washington, Seattle, WA, United States
| | - J-M Ramirez
- Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, WA, United States; Department of Neurological Surgery, University of Washington, Seattle, WA, United States
| | - N P Poolos
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, WA, United States.
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13
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Wang ZJ, Blanco I, Hayoz S, Brelidze TI. The HCN domain is required for HCN channel cell-surface expression and couples voltage- and cAMP-dependent gating mechanisms. J Biol Chem 2020; 295:8164-8173. [PMID: 32341127 DOI: 10.1074/jbc.ra120.013281] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/23/2020] [Indexed: 11/06/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are major regulators of synaptic plasticity and rhythmic activity in the heart and brain. Opening of HCN channels requires membrane hyperpolarization and is further facilitated by intracellular cyclic nucleotides (cNMPs). In HCN channels, membrane hyperpolarization is sensed by the membrane-spanning voltage sensor domain (VSD), and the cNMP-dependent gating is mediated by the intracellular cyclic nucleotide-binding domain (CNBD) connected to the pore-forming S6 transmembrane segment via the C-linker. Previous functional analysis of HCN channels has suggested a direct or allosteric coupling between the voltage- and cNMP-dependent activation mechanisms. However, the specifics of this coupling remain unclear. The first cryo-EM structure of an HCN1 channel revealed that a novel structural element, dubbed the HCN domain (HCND), forms a direct structural link between the VSD and C-linker-CNBD. In this study, we investigated the functional significance of the HCND. Deletion of the HCND prevented surface expression of HCN2 channels. Based on the HCN1 structure analysis, we identified Arg237 and Gly239 residues on the S2 of the VSD that form direct interactions with Ile135 on the HCND. Disrupting these interactions abolished HCN2 currents. We also identified three residues on the C-linker-CNBD (Glu478, Gln482, and His559) that form direct interactions with residues Arg154 and Ser158 on the HCND. Disrupting these interactions affected both voltage- and cAMP-dependent gating of HCN2 channels. These findings indicate that the HCND is necessary for the cell-surface expression of HCN channels and provides a functional link between voltage- and cAMP-dependent mechanisms of HCN channel gating.
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Affiliation(s)
- Ze-Jun Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA
| | - Ismary Blanco
- Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, D. C., USA
| | - Sebastien Hayoz
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA
| | - Tinatin I Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, D. C., USA .,Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, D. C., USA
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14
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Page DA, Magee KEA, Li J, Jung M, Young EC. Cytoplasmic Autoinhibition in HCN Channels is Regulated by the Transmembrane Region. J Membr Biol 2020; 253:153-166. [PMID: 32146488 PMCID: PMC7150657 DOI: 10.1007/s00232-020-00111-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 02/16/2020] [Indexed: 12/25/2022]
Abstract
Hyperpolarization-activated cation-nonselective (HCN) channels regulate electrical activity in the brain and heart in a cAMP-dependent manner. The voltage-gating of these channels is mediated by a transmembrane (TM) region but is additionally regulated by direct binding of cAMP to a cyclic nucleotide-binding (CNB) fold in the cytoplasmic C-terminal region. Cyclic AMP potentiation has been explained by an autoinhibition model which views the unliganded CNB fold as an inhibitory module whose influence is disrupted by cAMP binding. However, the HCN2 subtype uses two other CNB fold-mediated mechanisms called open-state trapping and Quick-Activation to respectively slow the deactivation kinetics and speed the activation kinetics, against predictions of an autoinhibition model. To test how these multiple mechanisms are influenced by the TM region, we replaced the TM region of HCN2 with that of HCN4. This HCN4 TM-replacement preserved cAMP potentiation but augmented the magnitude of autoinhibition by the unliganded CNB fold; it moreover disrupted open-state trapping and Quick-Activation so that autoinhibition became the dominant mechanism contributed by the C-terminal region to determine kinetics. Truncation within the CNB fold partially relieved this augmented autoinhibition. This argues against the C-terminal region acting like a portable module with consistent effects on TM regions of different subtypes. Our findings provide evidence that functional interactions between the HCN2 TM region and C-terminal region govern multiple CNB fold-mediated mechanisms, implying that the molecular mechanisms of autoinhibition, open-state trapping, and Quick-Activation include participation of TM region structures.
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Affiliation(s)
- Dana A Page
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Kaylee E A Magee
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.,Department of Biology, Kwantlen Polytechnic University, 12666 72 Avenue, Surrey, BC, V3W 2M8, Canada
| | - Jessica Li
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Matthew Jung
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Edgar C Young
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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15
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Incorporation of one N-glycosylation-deficient subunit within a tetramer of HCN2 channel is tolerated. Neuroreport 2019; 30:998-1003. [PMID: 31503201 DOI: 10.1097/wnr.0000000000001310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are glycoproteins N-glycosylated at a specific asparagine residue in the S5-S6 linker region. Previous reports suggested that N-glycosylation-deficient HCN2 N380Q (NQ) channels fail to properly target to the plasma membrane and are unable to form functional ion channels. HCN channels are known to homo- and hetero-oligomerize and it is not known whether HCN2-NQ subunits can oligomerize with wild type (wt) N-glycosylated subunits to form a tetrameric assembly. In the present study, homomeric NQ-mutant resulted in no current, cRNA titration experiments controlling the amount of wt-to-NQ injected into Xenopus oocytes indicated that the observed currents were consistent with a model where presence of a single nonglycosylated subunit in a tetrameric oligomer is tolerated forming functional channels. The activation voltage-dependence described by half-activation voltage and slope factor, and the reversal potential of the wt-NQ oligomeric channels were identical to the wt only tetrameric channels. Further incorporation of the nonglycosylated subunit rendered the channels nonconductive or not incorporated into the plasma membrane.
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16
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Rathour RK, Narayanan R. Degeneracy in hippocampal physiology and plasticity. Hippocampus 2019; 29:980-1022. [PMID: 31301166 PMCID: PMC6771840 DOI: 10.1002/hipo.23139] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 05/27/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022]
Abstract
Degeneracy, defined as the ability of structurally disparate elements to perform analogous function, has largely been assessed from the perspective of maintaining robustness of physiology or plasticity. How does the framework of degeneracy assimilate into an encoding system where the ability to change is an essential ingredient for storing new incoming information? Could degeneracy maintain the balance between the apparently contradictory goals of the need to change for encoding and the need to resist change towards maintaining homeostasis? In this review, we explore these fundamental questions with the mammalian hippocampus as an example encoding system. We systematically catalog lines of evidence, spanning multiple scales of analysis that point to the expression of degeneracy in hippocampal physiology and plasticity. We assess the potential of degeneracy as a framework to achieve the conjoint goals of encoding and homeostasis without cross-interferences. We postulate that biological complexity, involving interactions among the numerous parameters spanning different scales of analysis, could establish disparate routes towards accomplishing these conjoint goals. These disparate routes then provide several degrees of freedom to the encoding-homeostasis system in accomplishing its tasks in an input- and state-dependent manner. Finally, the expression of degeneracy spanning multiple scales offers an ideal reconciliation to several outstanding controversies, through the recognition that the seemingly contradictory disparate observations are merely alternate routes that the system might recruit towards accomplishment of its goals.
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Affiliation(s)
- Rahul K. Rathour
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
| | - Rishikesh Narayanan
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
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17
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Hammelmann V, Stieglitz MS, Hülle H, Le Meur K, Kass J, Brümmer M, Gruner C, Rötzer RD, Fenske S, Hartmann J, Zott B, Lüthi A, Spahn S, Moser M, Isbrandt D, Ludwig A, Konnerth A, Wahl-Schott C, Biel M. Abolishing cAMP sensitivity in HCN2 pacemaker channels induces generalized seizures. JCI Insight 2019; 4:126418. [PMID: 31045576 DOI: 10.1172/jci.insight.126418] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/02/2019] [Indexed: 12/17/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are dually gated channels that are operated by voltage and by neurotransmitters via the cAMP system. cAMP-dependent HCN regulation has been proposed to play a key role in regulating circuit behavior in the thalamus. By analyzing a knockin mouse model (HCN2EA), in which binding of cAMP to HCN2 was abolished by 2 amino acid exchanges (R591E, T592A), we found that cAMP gating of HCN2 is essential for regulating the transition between the burst and tonic modes of firing in thalamic dorsal-lateral geniculate (dLGN) and ventrobasal (VB) nuclei. HCN2EA mice display impaired visual learning, generalized seizures of thalamic origin, and altered NREM sleep properties. VB-specific deletion of HCN2, but not of HCN4, also induced these generalized seizures of the absence type, corroborating a key role of HCN2 in this particular nucleus for controlling consciousness. Together, our data define distinct pathological phenotypes resulting from the loss of cAMP-mediated gating of a neuronal HCN channel.
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Affiliation(s)
- Verena Hammelmann
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Marc Sebastian Stieglitz
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Henrik Hülle
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Karim Le Meur
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jennifer Kass
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Manuela Brümmer
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Gruner
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - René Dominik Rötzer
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefanie Fenske
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jana Hartmann
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Benedikt Zott
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Saskia Spahn
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Markus Moser
- Department for Molecular Medicine, Max-Planck-Institut für Biochemie, Martinsried, Germany
| | - Dirk Isbrandt
- DZNE Research Group, Experimental Neurophysiology, Institute for Molecular and Behavioral Neuroscience, University of Cologne, Germany
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Christian Wahl-Schott
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Institut für Neurophysiologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
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18
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Santos-Vera B, Vaquer-Alicea ADC, Maria-Rios CE, Montiel-Ramos A, Ramos-Cardona A, Vázquez-Torres R, Sanabria P, Jiménez-Rivera CA. Protein and surface expression of HCN2 and HCN4 subunits in mesocorticolimbic areas after cocaine sensitization. Neurochem Int 2019; 125:91-98. [PMID: 30794847 DOI: 10.1016/j.neuint.2019.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/05/2019] [Accepted: 02/06/2019] [Indexed: 01/20/2023]
Abstract
The Ih is a mixed depolarizing current present in neurons which, upon activation by hyperpolarization, modulates neuronal excitability in the mesocorticolimbic (MCL) system, an area which regulates emotions such as pleasure, reward, and motivation. Its biophysical properties are determined by HCN protein expression profiles, specifically HCN subunits 1-4. Previously, we reported that cocaine-induced behavioral sensitization increases HCN2 protein expression in all MCL areas with the Ventral Tegmental Area (VTA) showing the most significant increase. Recent evidence suggests that HCN4 also has an important expression in the MCL system. Although there is a significant expression of HCN channels in the MCL system their role in addictive processes is largely unknown. Thus, in this study we aim to compare HCN2 and HCN4 expression profiles and their cellular compartmental distribution in the MCL system, before and after cocaine sensitization. Surface/intracellular (S/I) ratio analysis indicates that VTA HCN2 subunits are mostly expressed in the cell surface in contrast to other areas tested. Our findings demonstrate that after cocaine sensitization, the HCN2 S/I ratio in the VTA was decreased whereas in the Prefrontal Cortex it was increased. In addition, HCN4 total expression in the VTA was decreased after cocaine sensitization, although the S/I ratio was not altered. Together, these results demonstrate differential cocaine effects on HCN2 and HCN4 protein expression profiles and therefore suggest a diverse Ih modulation of cellular activity during cocaine addictive processes.
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Affiliation(s)
- Bermary Santos-Vera
- Physiology Department, University of Puerto Rico, School of Medicine, Medical Sciences Campus, San Juan, 00936-5067, Puerto Rico
| | - Ana Del C Vaquer-Alicea
- Physiology Department, University of Puerto Rico, School of Medicine, Medical Sciences Campus, San Juan, 00936-5067, Puerto Rico
| | - Cristina E Maria-Rios
- Biology Department, University of Puerto Rico, Rio Piedras Campus, San Juan, 00936-5067, Puerto Rico
| | - Alan Montiel-Ramos
- Biology Department, University of Puerto Rico, Rio Piedras Campus, San Juan, 00936-5067, Puerto Rico
| | - Aynette Ramos-Cardona
- Psychology Department, University of Puerto Rico, Rio Piedras Campus, San Juan, 00936-5067, Puerto Rico
| | - Rafael Vázquez-Torres
- Physiology Department, University of Puerto Rico, School of Medicine, Medical Sciences Campus, San Juan, 00936-5067, Puerto Rico
| | - Priscila Sanabria
- Physiology Department, Universidad Central del Caribe, Bayamon, 00960, Puerto Rico
| | - Carlos A Jiménez-Rivera
- Physiology Department, University of Puerto Rico, School of Medicine, Medical Sciences Campus, San Juan, 00936-5067, Puerto Rico.
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19
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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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20
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HCN Channels: New Therapeutic Targets for Pain Treatment. Molecules 2018; 23:molecules23092094. [PMID: 30134541 PMCID: PMC6225464 DOI: 10.3390/molecules23092094] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/17/2018] [Accepted: 08/18/2018] [Indexed: 12/28/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are highly regulated proteins which respond to different cellular stimuli. The HCN currents (Ih) mediated by HCN1 and HCN2 drive the repetitive firing in nociceptive neurons. The role of HCN channels in pain has been widely investigated as targets for the development of new therapeutic drugs, but the comprehensive design of HCN channel modulators has been restricted due to the lack of crystallographic data. The three-dimensional structure of the human HCN1 channel was recently reported, opening new possibilities for the rational design of highly-selective HCN modulators. In this review, we discuss the structural and functional properties of HCN channels, their pharmacological inhibitors, and the potential strategies for designing new drugs to block the HCN channel function associated with pain perception.
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21
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Lopez-Rodriguez A, Holmgren M. Deglycosylation of Shaker K V channels affects voltage sensing and the open-closed transition. J Gen Physiol 2018; 150:1025-1034. [PMID: 29880580 PMCID: PMC6028503 DOI: 10.1085/jgp.201711958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 04/23/2018] [Accepted: 05/15/2018] [Indexed: 02/04/2023] Open
Abstract
Voltage-gated ion channels are subject to posttranslational modification, including glycosylation. Lopez-Rodriguez and Holmgren show that, in Shaker KV channels, deglycosylation influences voltage sensing and open–closed transitions but not binding of ligands to the protein. Most membrane proteins are subject to posttranslational glycosylation, which influences protein function, folding, solubility, stability, and trafficking. This modification has been proposed to protect proteins from proteolysis and modify protein–protein interactions. Voltage-activated ion channels are heavily glycosylated, which can result in up to 30% of the mature molecular mass being contributed by glycans. Normally, the functional consequences of glycosylation are assessed by comparing the function of fully glycosylated proteins with those in which glycosylation sites have been mutated or by expressing proteins in model cells lacking glycosylation enzymes. Here, we study the functional consequences of deglycosylation by PNGase F within the same population of voltage-activated potassium (KV) channels. We find that removal of sugar moieties has a small, but direct, influence on the voltage-sensing properties and final opening–closing transition of Shaker KV channels. Yet, we observe that the interactions of various ligands with different domains of the protein are not affected by deglycosylation. These results imply that the sugar mass attached to the voltage sensor neither represents a cargo for the dynamics of this domain nor imposes obstacles to the access of interacting molecules.
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Affiliation(s)
- Angelica Lopez-Rodriguez
- Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD .,Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, México
| | - Miguel Holmgren
- Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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22
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Riegelhaupt PM, Tibbs GR, Goldstein PA. HCN and K 2P Channels in Anesthetic Mechanisms Research. Methods Enzymol 2018; 602:391-416. [PMID: 29588040 DOI: 10.1016/bs.mie.2018.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ability of a diverse group of agents to produce general anesthesia has long been an area of intense speculation and investigation. Over the past century, we have seen a paradigm shift from proposing that the anesthetized state arises from nonspecific interaction of anesthetics with the lipid membrane to the recognition that the function of distinct, and identifiable, membrane-embedded proteins is dramatically altered in the presence of intravenous and inhaled agents. Among proteinaceous targets, metabotropic and ionotropic receptors garnered much of the attention over the last 30 years, and it is only relatively recently that voltage-gated ion channels have clearly and rigorously been shown to be important molecular targets. In this review, we will consider the experimental issues relevant to two important ion channel anesthetic targets, HCN and K2P.
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Affiliation(s)
| | - Gareth R Tibbs
- Weill Cornell Medical College, New York, NY, United States
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Sartiani L, Mannaioni G, Masi A, Novella Romanelli M, Cerbai E. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels. Pharmacol Rev 2017; 69:354-395. [PMID: 28878030 DOI: 10.1124/pr.117.014035] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.
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Affiliation(s)
- Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Alessio Masi
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
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Peripherin-2 and Rom-1 have opposing effects on rod outer segment targeting of retinitis pigmentosa-linked peripherin-2 mutants. Sci Rep 2017; 7:2321. [PMID: 28539581 PMCID: PMC5443838 DOI: 10.1038/s41598-017-02514-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022] Open
Abstract
Mutations in the photoreceptor outer segment (OS) specific peripherin-2 lead to autosomal dominant retinitis pigmentosa (adRP). By contrast, mutations in the peripherin-2 homolog Rom-1 cause digenic RP in combination with certain heterozygous mutations in peripherin-2. The mechanisms underlying the differential role of peripherin-2 and Rom-1 in RP pathophysiology remained elusive so far. Here, focusing on two adRP-linked peripherin-2 mutants, P210L and C214S, we analyzed the binding characteristics, protein assembly, and rod OS targeting of wild type (perWT), mutant peripherin-2 (perMT), or Rom-1 complexes, which can be formed in patients heterozygous for peripherin-2 mutations. Both mutants are misfolded and lead to decreased binding to perWT and Rom-1. Furthermore, both mutants are preferentially forming non-covalent perMT-perMT, perWT-perMT, and Rom-1-perMT dimers. However, only perWT-perMT, but not perMT-perMT or Rom-1-perMT complexes could be targeted to murine rod OS. Our study provides first evidence that non-covalent perWT-perMT dimers can be targeted to rod OS. Finally, our study unravels unexpected opposing roles of perWT and Rom-1 in rod OS targeting of adRP-linked peripherin-2 mutants and suggests a new treatment strategy for the affected individuals.
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Hyperpolarization-activated current I h in mouse trigeminal sensory neurons in a transgenic mouse model of familial hemiplegic migraine type-1. Neuroscience 2017; 351:47-64. [DOI: 10.1016/j.neuroscience.2017.03.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 03/15/2017] [Accepted: 03/20/2017] [Indexed: 12/19/2022]
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27
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Jiang N, Wu J, Leng T, Yang T, Zhou Y, Jiang Q, Wang B, Hu Y, Ji YH, Simon RP, Chu XP, Xiong ZG, Zha XM. Region specific contribution of ASIC2 to acidosis-and ischemia-induced neuronal injury. J Cereb Blood Flow Metab 2017; 37:528-540. [PMID: 26861816 PMCID: PMC5381448 DOI: 10.1177/0271678x16630558] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acidosis in the brain plays a critical role in neuronal injury in neurological diseases, including brain ischemia. One key mediator of acidosis-induced neuronal injury is the acid-sensing ion channels (ASICs). Current literature has focused on ASIC1a when studying acid signaling. The importance of ASIC2, which is also widely expressed in the brain, has not been appreciated. We found here a region-specific effect of ASIC2 on acid-mediated responses. Deleting ASIC2 reduced acid-activated current in cortical and striatal neurons, but had no significant effect in cerebellar granule neurons. In addition, we demonstrated that ASIC2 was important for ASIC1a expression, and that ASIC2a but not 2b facilitated ASIC1a surface trafficking in the brain. Further, we showed that ASIC2 deletion attenuated acidosis/ischemia-induced neuronal injury in organotypic hippocampal slices but had no effect in organotypic cerebellar slices. Consistent with an injurious role of ASIC2, we showed that ASIC2 deletion significantly protected the mouse brain from ischemic damage in vivo. These data suggest a critical region-specific contribution of ASIC2 to neuronal injury and reveal an important functional difference between ASIC2a and 2b in the brain.
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Affiliation(s)
- Nan Jiang
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA.,2 School of Life Sciences, Shanghai University, Shanghai, China
| | - Junjun Wu
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA.,3 China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Tiandong Leng
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Tao Yang
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Yufan Zhou
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA
| | - Qian Jiang
- 5 Department of Basic Medical Science, University of Missouri-Kansas City, Kansas City, USA
| | - Bin Wang
- 6 Department of Mathematics and Statistics, University of South Alabama, Mobile, USA
| | - Youjia Hu
- 3 China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Yong-Hua Ji
- 2 School of Life Sciences, Shanghai University, Shanghai, China
| | - Roger P Simon
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Xiang-Ping Chu
- 5 Department of Basic Medical Science, University of Missouri-Kansas City, Kansas City, USA
| | - Zhi-Gang Xiong
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Xiang-Ming Zha
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA
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28
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Parker AR, Welch MA, Forster LA, Tasneem SM, Dubhashi JA, Baro DJ. SUMOylation of the Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel 2 Increases Surface Expression and the Maximal Conductance of the Hyperpolarization-Activated Current. Front Mol Neurosci 2017; 9:168. [PMID: 28127275 PMCID: PMC5226956 DOI: 10.3389/fnmol.2016.00168] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 12/26/2016] [Indexed: 11/13/2022] Open
Abstract
Small Ubiquitin-like Modifier (SUMO) is a ∼10 kDa peptide that can be post-translationally added to a lysine (K) on a target protein to facilitate protein–protein interactions. Recent studies have found that SUMOylation can be regulated in an activity-dependent manner and that ion channel SUMOylation can alter the biophysical properties and surface expression of the channel. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel surface expression can be regulated in an activity-dependent manner through unknown processes. We hypothesized that SUMOylation might influence the surface expression of HCN2 channels. In this manuscript, we show that HCN2 channels are SUMOylated in the mouse brain. Baseline levels of SUMOylation were also observed for a GFP-tagged HCN2 channel stably expressed in Human embryonic kidney (Hek) cells. Elevating GFP-HCN2 channel SUMOylation above baseline in Hek cells led to an increase in surface expression that augmented the hyperpolarization-activated current (Ih) mediated by these channels. Increased SUMOylation did not alter Ih voltage-dependence or kinetics of activation. There are five predicted intracellular SUMOylation sites on HCN2. Site-directed mutagenesis indicated that more than one K on the GFP-HCN2 channel was SUMOylated. Enhancing SUMOylation at one of the five predicted sites, K669, led to the increase in surface expression and IhGmax. The role of SUMOylation at additional sites is currently unknown. The SUMOylation site at K669 is also conserved in HCN1 channels. Aberrant SUMOylation has been linked to neurological diseases that also display alterations in HCN1 and HCN2 channel expression, such as seizures and Parkinson’s disease. This work is the first report that HCN channels can be SUMOylated and that this can regulate surface expression and Ih.
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Affiliation(s)
- Anna R Parker
- Department of Biology, Georgia State University Atlanta, GA, USA
| | - Meghyn A Welch
- Department of Biology, Georgia State University Atlanta, GA, USA
| | - Lori A Forster
- Neuroscience Institute, Georgia State University Atlanta, GA, USA
| | - Sarah M Tasneem
- Department of Biology, Georgia State University Atlanta, GA, USA
| | | | - Deborah J Baro
- Department of Biology, Georgia State UniversityAtlanta, GA, USA; Neuroscience Institute, Georgia State UniversityAtlanta, GA, USA
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Negrini D, Marcozzi C, Solari E, Bossi E, Cinquetti R, Reguzzoni M, Moriondo A. Hyperpolarization-activated cyclic nucleotide-gated channels in peripheral diaphragmatic lymphatics. Am J Physiol Heart Circ Physiol 2016; 311:H892-H903. [DOI: 10.1152/ajpheart.00193.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 08/01/2016] [Indexed: 11/22/2022]
Abstract
Diaphragmatic lymphatic function is mainly sustained by pressure changes in the tissue and serosal cavities during cardiorespiratory cycles. The most peripheral diaphragmatic lymphatics are equipped with muscle cells (LMCs), which exhibit spontaneous contraction, whose molecular machinery is still undetermined. Hypothesizing that spontaneous contraction might involve hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in lymphatic LMCs, diaphragmatic specimens, including spontaneously contracting lymphatics, were excised from 33 anesthetized rats, moved to a perfusion chamber containing HEPES-Tyrode's solution, and treated with HCN channels inhibitors cesium chloride (CsCl), ivabradine, and ZD-7288. Compared with control, exposure to 10 mM CsCl reduced (−65%, n = 13, P < 0.01) the contraction frequency (FL) and increased end-diastolic diameter (DL-d, +7.3%, P < 0.01) without changes in end-systolic diameter (DL-s). Ivabradine (300 μM) abolished contraction and increased DL-d (−14%, n = 10, P < 0.01) or caused an incomplete inhibition of FL ( n = 3, P < 0.01), leaving DL-d and DL-s unaltered. ZD-7288 (200 μM) completely ( n = 12, P < 0.01) abolished FL, while DL-d decreased to 90.9 ± 2.7% of control. HCN gene expression and immunostaining confirmed the presence of HCN1-4 channel isoforms, likely arranged in different configurations, in LMCs. Hence, all together, data suggest that HCN channels might play an important role in affecting contraction frequency of LMCs.
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Affiliation(s)
- Daniela Negrini
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Cristiana Marcozzi
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Eleonora Solari
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Elena Bossi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Marcella Reguzzoni
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
| | - Andrea Moriondo
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and
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30
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Characteristics of hyperpolarization-activated cyclic nucleotide-gated channels in dorsal root ganglion neurons at different ages and sizes. Neuroreport 2016; 26:981-7. [PMID: 26379059 DOI: 10.1097/wnr.0000000000000455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In rat's sensory neurons, hyperpolarization-activated inward currents (Ih) play an essential role in mediating action potentials and contributing to neuronal excitability. Classified by the size of neurons and ages, we studied the Ih and transcription levels of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels using electrophysiology and the single-cell RT-PCR. In voltage-clamp studies, Ih and half-maximal activation voltage (V1/2) changed with age and size. An analysis of all HCN subtypes in dorsal root ganglion (DRG) neurons by single-cell RT-PCR was carried out. HCN1 and HCN3 in medium-small elderly neurons had a weak expression. HCN2 in newborns and HCN4 in elderly rats also had a weak expression. The aim of this study is to examine the age-related Ih and HCN channels subunits in different ages and sizes of DRG neurons. The results would be significant in understanding the physiological and pathophysiological function of different sizes of DRG neurons in different age periods.
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31
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Tibbs GR, Posson DJ, Goldstein PA. Voltage-Gated Ion Channels in the PNS: Novel Therapies for Neuropathic Pain? Trends Pharmacol Sci 2016; 37:522-542. [DOI: 10.1016/j.tips.2016.05.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/24/2016] [Accepted: 05/03/2016] [Indexed: 12/19/2022]
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32
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Nguyen ONP, Böhm S, Gießl A, Butz ES, Wolfrum U, Brandstätter JH, Wahl-Schott C, Biel M, Becirovic E. Peripherin-2 differentially interacts with cone opsins in outer segments of cone photoreceptors. Hum Mol Genet 2016; 25:2367-2377. [PMID: 27033727 DOI: 10.1093/hmg/ddw103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 11/13/2022] Open
Abstract
Peripherin-2 is a glycomembrane protein exclusively expressed in the light-sensing compartments of rod and cone photoreceptors designated as outer segments (OS). Mutations in peripherin-2 are associated with degenerative retinal diseases either affecting rod or cone photoreceptors. While peripherin-2 has been extensively studied in rods, there is only little information on its supramolecular organization and function in cones. Recently, we have demonstrated that peripherin-2 interacts with the light detector rhodopsin in OS of rods. It remains unclear, however, if peripherin-2 also binds to cone opsins. Here, using a combination of co-immunoprecipitation analyses, transmission electron microscopy (TEM)-based immunolabeling experiments, and quantitative fluorescence resonance energy transfer (FRET) measurements in cone OS of wild type mice, we demonstrate that peripherin-2 binds to both, S-opsin and M-opsin. However, FRET-based quantification of the respective interactions indicated significantly less stringent binding of peripherin-2 to S-opsin compared to its interaction with M-opsin. Subsequent TEM-studies also showed less co-localization of peripherin-2 and S-opsin in cone OS compared to peripherin-2 and M-opsin. Furthermore, quantitative FRET analysis in acutely isolated cone OS revealed that the cone degeneration-causing V268I mutation in peripherin-2 selectively reduced binding to M-opsin without affecting the peripherin-2 interaction to S-opsin or rhodopsin. The differential binding of peripherin-2 to cone opsins and the mutant-specific interference with the peripherin-2/M-opsin binding points to a novel role of peripherin-2 in cones and might contribute to understanding the differential penetrance of certain peripherin-2 mutations in rods and cones. Finally, our results provide a proof-of-principle for quantitative FRET measurements of protein-protein interactions in cone OS.
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Affiliation(s)
- O N Phuong Nguyen
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Sybille Böhm
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Andreas Gießl
- Department of Biology, Animal Physiology, Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany and
| | - Elisabeth S Butz
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Uwe Wolfrum
- Cell and Matrix Biology, Institute of Zoology, Johannes-Gutenberg Universität Mainz, 55128 Mainz, Germany
| | - Johann H Brandstätter
- Department of Biology, Animal Physiology, Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany and
| | - Christian Wahl-Schott
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Martin Biel
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Elvir Becirovic
- Munich Center for Integrated Protein Science CIPS , 81377 München, Germany, .,Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 München, Germany
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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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Becirovic E, Böhm S, Nguyen ONP, Riedmayr LM, Koch MA, Schulze E, Kohl S, Borsch O, Santos-Ferreira T, Ader M, Michalakis S, Biel M. In Vivo Analysis of Disease-Associated Point Mutations Unveils Profound Differences in mRNA Splicing of Peripherin-2 in Rod and Cone Photoreceptors. PLoS Genet 2016; 12:e1005811. [PMID: 26796962 PMCID: PMC4722987 DOI: 10.1371/journal.pgen.1005811] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 12/22/2015] [Indexed: 01/24/2023] Open
Abstract
Point mutations in peripherin-2 (PRPH2) are associated with severe retinal degenerative disorders affecting rod and/or cone photoreceptors. Various disease-causing mutations have been identified, but the exact contribution of a given mutation to the clinical phenotype remains unclear. Exonic point mutations are usually assumed to alter single amino acids, thereby influencing specific protein characteristics; however, they can also affect mRNA splicing. To examine the effects of distinct PRPH2 point mutations on mRNA splicing and protein expression in vivo, we designed PRPH2 minigenes containing the three coding exons and relevant intronic regions of human PRPH2. Minigenes carrying wild type PRPH2 or PRPH2 exon 2 mutations associated with rod or cone disorders were expressed in murine photoreceptors using recombinant adeno-associated virus (rAAV) vectors. We detect three PRPH2 splice isoforms in rods and cones: correctly spliced, intron 1 retention, and unspliced. In addition, we show that only the correctly spliced isoform results in detectable protein expression. Surprisingly, compared to rods, differential splicing leads to lower expression of correctly spliced and higher expression of unspliced PRPH2 in cones. These results were confirmed in qRT-PCR experiments from FAC-sorted murine rods and cones. Strikingly, three out of five cone disease-causing PRPH2 mutations profoundly enhanced correct splicing of PRPH2, which correlated with strong upregulation of mutant PRPH2 protein expression in cones. By contrast, four out of six PRPH2 mutants associated with rod disorders gave rise to a reduced PRPH2 protein expression via different mechanisms. These mechanisms include aberrant mRNA splicing, protein mislocalization, and protein degradation. Our data suggest that upregulation of PRPH2 levels in combination with defects in the PRPH2 function caused by the mutation might be an important mechanism leading to cone degeneration. By contrast, the pathology of rod-specific PRPH2 mutations is rather characterized by PRPH2 downregulation and impaired protein localization. Photoreceptors are the light sensing cells of the retina and consist of dim light and night vision mediating rods and daylight and color vision mediating cones. PRPH2 is crucial for the structural and functional integrity of photoreceptors. Some point mutations in PRPH2 lead to degeneration of rods, whereas others only affect cones. We examined the potential effects of 11 disease-linked PRPH2 mutations on mRNA splicing and protein expression in vivo. For this, we expressed six PRPH2 mutants associated with degeneration of rods in murine rods and five additional mutants linked to cone diseases in murine cones. We demonstrate that different splicing efficiencies of PRPH2 lead to its high expression in rods and to its low expression in cones. Furthermore, we show that the majority of PRPH2 mutants associated with cone disorders results in an upregulation of PRPH2 expression in cones by increasing the mRNA splicing efficiency. By contrast, the majority of PRPH2 mutants associated with rod diseases leads to a downregulation of PRPH2 expression in rods via different mechanisms including aberrant mRNA splicing. These results provide novel insights into the pathobiology of mRNA splicing in photoreceptors and might contribute to explain the differential penetrance of PRPH2 mutants in rods and cones.
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Affiliation(s)
- Elvir Becirovic
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
- * E-mail: (EB); (MB)
| | - Sybille Böhm
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Ong Nam Phuong Nguyen
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Lisa Maria Riedmayr
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Mirja Annika Koch
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Elisabeth Schulze
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Oliver Borsch
- Technische Universität Dresden, CRTD/DFG-Center for Regenerative Therapies Dresden, Cluster of Excellence, Dresden, Germany
| | - Tiago Santos-Ferreira
- Technische Universität Dresden, CRTD/DFG-Center for Regenerative Therapies Dresden, Cluster of Excellence, Dresden, Germany
| | - Marius Ader
- Technische Universität Dresden, CRTD/DFG-Center for Regenerative Therapies Dresden, Cluster of Excellence, Dresden, Germany
| | - Stylianos Michalakis
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
| | - Martin Biel
- Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, München, Germany
- Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, München, Germany
- * E-mail: (EB); (MB)
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35
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Gessele N, Garcia-Pino E, Omerbašić D, Park TJ, Koch U. Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber). PLoS One 2016; 11:e0146428. [PMID: 26760498 PMCID: PMC4711988 DOI: 10.1371/journal.pone.0146428] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 12/15/2015] [Indexed: 11/22/2022] Open
Abstract
Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.
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Affiliation(s)
- Nikodemus Gessele
- Neurophysiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Elisabet Garcia-Pino
- Neurophysiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Damir Omerbašić
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Thomas J. Park
- Laboratory of Integrative Neuroscience, Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Ursula Koch
- Neurophysiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
- * E-mail:
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Schön C, Asteriti S, Koch S, Sothilingam V, Garrido MG, Tanimoto N, Herms J, Seeliger MW, Cangiano L, Biel M, Michalakis S. Loss of HCN1 enhances disease progression in mouse models of CNG channel-linked retinitis pigmentosa and achromatopsia. Hum Mol Genet 2016; 25:1165-75. [DOI: 10.1093/hmg/ddv639] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/22/2015] [Indexed: 01/24/2023] Open
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Wemhöner K, Kanyshkova T, Silbernagel N, Fernandez-Orth J, Bittner S, Kiper AK, Rinné S, Netter MF, Meuth SG, Budde T, Decher N. An N-terminal deletion variant of HCN1 in the epileptic WAG/Rij strain modulates HCN current densities. Front Mol Neurosci 2015; 8:63. [PMID: 26578877 PMCID: PMC4630678 DOI: 10.3389/fnmol.2015.00063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/13/2015] [Indexed: 11/26/2022] Open
Abstract
Rats of the Wistar Albino Glaxo/Rij (WAG/Rij) strain show symptoms resembling human absence epilepsy. Thalamocortical neurons of WAG/Rij rats are characterized by an increased HCN1 expression, a negative shift in Ih activation curve, and an altered responsiveness of Ih to cAMP. We cloned HCN1 channels from rat thalamic cDNA libraries of the WAG/Rij strain and found an N-terminal deletion of 37 amino acids. In addition, WAG-HCN1 has a stretch of six amino acids, directly following the deletion, where the wild-type sequence (GNSVCF) is changed to a polyserine motif. These alterations were found solely in thalamus mRNA but not in genomic DNA. The truncated WAG-HCN1 was detected late postnatal in WAG/Rij rats and was not passed on to rats obtained from pairing WAG/Rij and non-epileptic August Copenhagen Irish rats. Heterologous expression in Xenopus oocytes revealed 2.2-fold increased current amplitude of WAG-HCN1 compared to rat HCN1. While WAG-HCN1 channels did not have altered current kinetics or changed regulation by protein kinases, fluorescence imaging revealed a faster and more pronounced surface expression of WAG-HCN1. Using co-expression experiments, we found that WAG-HCN1 channels suppress heteromeric HCN2 and HCN4 currents. Moreover, heteromeric channels of WAG-HCN1 with HCN2 have a reduced cAMP sensitivity. Functional studies revealed that the gain-of-function of WAG-HCN1 is not caused by the N-terminal deletion alone, thus requiring a change of the N-terminal GNSVCF motif. Our findings may help to explain previous observations in neurons of the WAG/Rij strain and indicate that WAG-HCN1 may contribute to the genesis of absence seizures in WAG/Rij rats.
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Affiliation(s)
- Konstantin Wemhöner
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Tatyana Kanyshkova
- Institute for Physiology I, Westfälische Wilhelms-Universität Münster, Germany
| | - Nicole Silbernagel
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | | | - Stefan Bittner
- Department of Neurology, University Medical Center, Johannes Gutenberg-University Mainz Mainz, Germany
| | - Aytug K Kiper
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Michael F Netter
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms-Universität Münster, Germany
| | - Thomas Budde
- Institute for Physiology I, Westfälische Wilhelms-Universität Münster, Germany
| | - Niels Decher
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
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López-González Z, Ayala-Aguilera C, Martinez-Morales F, Galicia-Cruz O, Salvador-Hernández C, Pedraza-Chaverri J, Medeiros M, Hernández AM, Escobar LI. Immunolocalization of hyperpolarization-activated cationic HCN1 and HCN3 channels in the rat nephron: regulation of HCN3 by potassium diets. Histochem Cell Biol 2015; 145:25-40. [PMID: 26515056 DOI: 10.1007/s00418-015-1375-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2015] [Indexed: 12/22/2022]
Abstract
Hyperpolarization-activated cationic and cyclic nucleotide-gated channels (HCN) comprise four homologous subunits (HCN1-HCN4). HCN channels are found in excitable and non-excitable tissues in mammals. We have previously shown that HCN2 may transport ammonium (NH4 (+)), besides sodium (Na(+)), in the rat distal nephron. In the present work, we identified HCN1 and HCN3 in the proximal tubule (PT) and HCN3 in the thick ascending limb of Henle (TALH) of the rat kidney. Immunoblot assays detected HCN1 (130 kDa) and HCN3 (90 KDa) and their truncated proteins C-terminal HCN1 (93 KDa) and N-terminal HCN3 (65 KDa) in enriched plasma membranes from cortex (CX) and outer medulla (OM), as well as in brush-border membrane vesicles. Immunofluorescence assays confirmed apical localization of HCN1 and HCN3 in the PT. HCN3 was also found at the basolateral membrane of TALH. We evaluated chronic changes in mineral dietary on HCN3 protein abundance. Animals were fed with three different diets: sodium-deficient (SD) diet, potassium-deficient (KD) diet, and high-potassium (HK) diet. Up-regulation of HCN3 was observed in OM by KD and in CX and OM by HK; the opposite effect occurred with the N-terminal truncated HCN3 in CX (KD) and OM (HK). SD diet did not produce any change. Since HCN channels activate with membrane hyperpolarization, our results suggest that HCN channels may play a role in the Na(+)-K(+)-ATPase activity, contributing to Na(+), K(+), and acid-base homeostasis in the rat kidney.
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Affiliation(s)
- Zinaeli López-González
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico, DF, México
| | - Cosete Ayala-Aguilera
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico, DF, México
| | - Flavio Martinez-Morales
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Othir Galicia-Cruz
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Carolina Salvador-Hernández
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico, DF, México
| | - José Pedraza-Chaverri
- Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México, México, DF, México
| | - Mara Medeiros
- Laboratorio de Investigación en Nefrología y Metabolismo Mineral Óseo, Hospital Infantil de México Federico Gómez, México, México
| | - Ana Maria Hernández
- Laboratorio de Investigación en Nefrología y Metabolismo Mineral Óseo, Hospital Infantil de México Federico Gómez, México, México
| | - Laura I Escobar
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico, DF, México.
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Smith T, Al Otaibi M, Sathish J, Djouhri L. Increased expression of HCN2 channel protein in L4 dorsal root ganglion neurons following axotomy of L5- and inflammation of L4-spinal nerves in rats. Neuroscience 2015; 295:90-102. [DOI: 10.1016/j.neuroscience.2015.03.041] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/28/2015] [Accepted: 03/19/2015] [Indexed: 12/31/2022]
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Effects of N-glycosylation on hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Biochem J 2015; 466:77-84. [PMID: 25423599 DOI: 10.1042/bj20140692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are activated by membrane hyperpolarization and conduct an inward cation current, which contributes to rhythmic electrical activity of neural and cardiac pacemaker cells. HCN channels have been shown to undergo N-linked glycosylation, and the N-glycosylation has been shown to be required for membrane trafficking and possibly function. In this study, recombinant wild-type (WT) and glycosylation-defective N380Q HCN2 channels were individually or co-expressed in HEK-293 cells. We demonstrate that glycosylation is required for trafficking to the plasma membrane and for the stability of HCN channels in the cell. Interestingly, the heteromeric HCN2 channels of WT and glycosylation-defective N380Q have been observed on cell membranes, indicating that not all four subunits of a tetrameric HCN2 channel need to be glycosylated for HCN2 channels to traffic to plasma membranes. Subsequently, we investigate the effect of N-glycosylation on the function of HCN2 channels. We developed a fluorescence-based flux assay, which makes it possible to establish a negative potential inside liposomes to open HCN2 channels. Using this flux assay, we demonstrate that glycosylation-defective N380Q HCN2 channels reconstituted into liposomes function similarly to WT HCN2 channels. This suggests that N-glycosylation is not required for HCN2 channels to function.
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Herrmann S, Schnorr S, Ludwig A. HCN channels--modulators of cardiac and neuronal excitability. Int J Mol Sci 2015; 16:1429-47. [PMID: 25580535 PMCID: PMC4307311 DOI: 10.3390/ijms16011429] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/31/2014] [Indexed: 01/06/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1-4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides and the modulation by tyrosine phosphorylation. The four isoforms are differentially expressed in various excitable tissues. This review will mainly focus on recent insights into the functional role of the channels apart from their classic role as pacemakers. The importance of HCN channels in the cardiac ventricle and ventricular hypertrophy will be discussed. In addition, their functional significance in the peripheral nervous system and nociception will be examined. The data, which are mainly derived from studies using transgenic mice, suggest that HCN channels contribute significantly to cellular excitability in these tissues. Remarkably, the impact of the channels is clearly more pronounced in pathophysiological states including ventricular hypertrophy as well as neural inflammation and neuropathy suggesting that HCN channels may constitute promising drug targets in the treatment of these conditions. This perspective as well as the current therapeutic use of HCN blockers will also be addressed.
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Affiliation(s)
- Stefan Herrmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Sabine Schnorr
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
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Yoshimoto R, Iwasaki S, Takago H, Nakajima T, Sahara Y, Kitamura K. Developmental increase in hyperpolarization-activated current regulates intrinsic firing properties in rat vestibular ganglion cells. Neuroscience 2014; 284:632-642. [PMID: 25450961 DOI: 10.1016/j.neuroscience.2014.10.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 12/22/2022]
Abstract
The primary vestibular neurons convey afferent information from hair cells in the inner ear to the vestibular nuclei and the cerebellum. The intrinsic firing properties of vestibular ganglion cells (VGCs) are heterogeneous to sustained membrane depolarization, and undergo marked developmental changes from phasic to tonic types during the early postnatal period. Previous studies have shown that low-voltage-activated potassium channels, Kv1 and Kv7, play a critical role in determining the firing pattern of VGCs. In the present study, we explored the developmental changes in the properties of hyperpolarization-activated current (Ih) in rat VGCs and the role played by Ih in determining the firing properties of VGCs. Tonic firing VGCs showed a larger current density of Ih as compared to phasic firing VGCs, and tonic firing VGCs became phasic firing in the presence of ZD7288, an Ih channel blocker, indicating that Ih contributes to control the firing pattern of VGCs. The amplitude of Ih increased and the activation kinetics of Ih became faster during the developmental period. Analysis of developmental changes in the expression of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels revealed that expression of HCN1 protein and its mRNA increased during the developmental period, whereas expression of HCN2-4 protein and its mRNA did not change. Our results suggest that HCN1 channels as well as Kv1 channels are critical in determining the firing pattern of rat VGCs and that developmental up-regulation of HCN1 transforms VGCs from phasic to tonic firing phenotypes.
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Affiliation(s)
- R Yoshimoto
- Department of Otolaryngology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - S Iwasaki
- Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
| | - H Takago
- Department of Rehabilitation for Sensory Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Saitama, Japan
| | - T Nakajima
- Department of Circular Physiology, Faculty of Medicine, University of Tokyo, Tokyo, Japan
| | - Y Sahara
- Department of Physiology, Iwate Medical University, School of Dentistry, Iwate, Japan
| | - K Kitamura
- Department of Otolaryngology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
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43
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Calejo AI, Reverendo M, Silva VS, Pereira PM, Santos MAS, Zorec R, Gonçalves PP. Differences in the expression pattern of HCN isoforms among mammalian tissues: sources and implications. Mol Biol Rep 2014; 41:297-307. [PMID: 24234751 DOI: 10.1007/s11033-013-2862-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 11/05/2013] [Indexed: 01/28/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play a critical role in a broad range of cell types, but the expression of the various HCN isoforms is still poorly understood. In the present study we have compared the expression of HCN isoforms in rat excitable and non-excitable tissues at both the mRNA and protein levels. Real-time PCR and Western blot analysis revealed distinct expression patterns of the four HCN isoforms in brain, heart, pituitary and kidney, with inconsistent mRNA-protein expression correlation. The HCN2 was the most abundant mRNA transcript (95.6, 78.0 and 59.0 % in kidney heart and pituitary, respectively) except in the brain (42.0 %) whereas HCN4 was the most abundant protein isoform. Our results suggest that HCN channels are mostly produced by the HCN4 isoform in heart, which contrasts with the sharp differences in the isoform stoichiometry in pituitary (15 HCN4:2 HCN2:1 HCN1:1 HCN3), kidney (24 HCN4:2 HCN3:1 HCN2:1 HCN1) and brain (3 HCN4:2 HCN2:1 HCN1:1 HCN3). Moreover, deviations of the electrophoretic molecular weight (MW) of the HCN isoforms relative to the theoretical MW were observed, suggesting that N-glycosylation and enzymatic proteolysis influences HCN channel surface expression. We hypothesize that selective cleavage of HCN channels by membrane bound metalloendopeptidases could account for the multiplicity of properties of native HCN channels in different tissues.
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44
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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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45
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Wilkars W, Wollberg J, Mohr E, Han M, Chetkovich DM, Bähring R, Bender RA. Nedd4‐2 regulates surface expression and may affect
N
‐glycosylation of hyperpolarization‐activated cyclic nucleotide‐gated (HCN)‐1 channels. FASEB J 2014; 28:2177-90. [DOI: 10.1096/fj.13-242032] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Wiebke Wilkars
- Institute of NeuroanatomyUniversity of Hamburg Medical CenterHamburgGermany
| | - Jessica Wollberg
- Institute of Cellular and Integrative PhysiologyUniversity of Hamburg Medical CenterHamburgGermany
| | - Evita Mohr
- Institute of NeuroanatomyUniversity of Hamburg Medical CenterHamburgGermany
| | - Mieri Han
- Institute of NeuroanatomyUniversity of Hamburg Medical CenterHamburgGermany
| | - Dane M. Chetkovich
- Davee Department of Neurology and Clinical NeurosciencesNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
- Department of PhysiologyNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
| | - Robert Bähring
- Institute of Cellular and Integrative PhysiologyUniversity of Hamburg Medical CenterHamburgGermany
| | - Roland A. Bender
- Institute of NeuroanatomyUniversity of Hamburg Medical CenterHamburgGermany
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47
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He C, Chen F, Li B, Hu Z. Neurophysiology of HCN channels: From cellular functions to multiple regulations. Prog Neurobiol 2014; 112:1-23. [DOI: 10.1016/j.pneurobio.2013.10.001] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 10/01/2013] [Accepted: 10/07/2013] [Indexed: 12/18/2022]
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48
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Klöckner U, Rueckschloss U, Grossmann C, Matzat S, Schumann K, Ebelt H, Müller-Werdan U, Loppnow H, Werdan K, Gekle M. Inhibition of cardiac pacemaker channel hHCN2 depends on intercalation of lipopolysaccharide into channel-containing membrane microdomains. J Physiol 2013; 592:1199-211. [PMID: 24366264 DOI: 10.1113/jphysiol.2013.268540] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Depressed heart rate variability in severe inflammatory diseases can be partially explained by the lipopolysaccharide (LPS)-dependent modulation of cardiac pacemaker channels. Recently, we showed that LPS inhibits pacemaker current in sinoatrial node cells and in HEK293 cells expressing cloned pacemaker channels, respectively. The present study was designed to verify whether this inhibition involves LPS-dependent intracellular signalling and to identify structures of LPS responsible for pacemaker current modulation. We examined the effect of LPS on the activity of human hyperpolarization-activated cyclic nucleotide-gated channel 2 (hHCN2) stably expressed in HEK293 cells. In whole-cell recordings, bath application of LPS decreased pacemaker current (IhHCN2) amplitude. The same protocol had no effect on channel activity in cell-attached patch recordings, in which channels are protected from the LPS-containing bath solution. This demonstrates that LPS must interact directly with or close to the channel protein. After cleavage of LPS into lipid A and the polysaccharide chain, neither of them alone impaired IhHCN2, which suggests that modulation of channel activity critically depends on the integrity of the entire LPS molecule. We furthermore showed that β-cyclodextrin interfered with LPS-dependent channel modulation predominantly via scavenging of lipid A, thereby abrogating the capability of LPS to intercalate into target cell membranes. We conclude that LPS impairs IhHCN2 by a local mechanism that is restricted to the vicinity of the channels. Furthermore, intercalation of lipid A into target cell membranes is a prerequisite for the inhibition that is suggested to depend on the direct interaction of the LPS polysaccharide chain with cardiac pacemaker channels.
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Affiliation(s)
- Udo Klöckner
- Julius Bernstein Institut für Physiologie, Martin Luther Universität Halle-Wittenberg, Magdeburger Strasse 6, 06112 Halle (Saale), Germany.
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49
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Nakamura Y, Shi X, Numata T, Mori Y, Inoue R, Lossin C, Baram TZ, Hirose S. Novel HCN2 mutation contributes to febrile seizures by shifting the channel's kinetics in a temperature-dependent manner. PLoS One 2013; 8:e80376. [PMID: 24324597 PMCID: PMC3851455 DOI: 10.1371/journal.pone.0080376] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 10/02/2013] [Indexed: 12/27/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated currents, known as I h, are involved in the control of rhythmic activity in neuronal circuits and in determining neuronal properties including the resting membrane potential. Recent studies have shown that HCN channels play a role in seizure susceptibility and in absence and limbic epilepsy including temporal lobe epilepsy following long febrile seizures (FS). This study focused on the potential contributions of abnormalities in the HCN2 isoform and their role in FS. A novel heterozygous missense mutation in HCN2 exon 1 leading to p.S126L was identified in two unrelated patients with FS. The mutation was inherited from the mother who had suffered from FS in a pedigree. To determine the effect of this substitution we conducted whole-cell patch clamp electrophysiology. We found that mutant channels had elevated sensitivity to temperature. More specifically, they displayed faster kinetics at higher temperature. Kinetic shift by change of temperature sensitivity rather than the shift of voltage dependence led to increased availability of I h in conditions promoting FS. Responses to cyclic AMP did not differ between wildtype and mutant channels. Thus, mutant HCN2 channels cause significant cAMP-independent enhanced availability of I h during high temperatures, which may contribute to hyperthermia-induced neuronal hyperexcitability in some individuals with FS.
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Affiliation(s)
- Yuki Nakamura
- Department of Pediatrics, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Xiuyu Shi
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China
| | - Tomohiro Numata
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Ryuji Inoue
- Department of Physiology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Christoph Lossin
- Department of Neurology, School of Medicine University of California Davis, Sacramento, California, United States of America
| | - Tallie Z. Baram
- Departments of Anatomy & Neurobiology, Pediatrics, and Neurology, University of California Irvine, Irvine, California, United States of America
| | - Shinichi Hirose
- Department of Pediatrics, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
- * E-mail:
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50
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Meighan SE, Meighan PC, Rich ED, Brown RL, Varnum MD. Cyclic nucleotide-gated channel subunit glycosylation regulates matrix metalloproteinase-dependent changes in channel gating. Biochemistry 2013; 52:8352-62. [PMID: 24164424 DOI: 10.1021/bi400824x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cyclic-nucleotide gated (CNG) channels are essential for phototransduction within retinal photoreceptors. We have demonstrated previously that the enzymatic activity of matrix metalloproteinase-2 and -9, members of the matrix metalloproteinase (MMP) family of extracellular, Ca(2+)- and Zn(2+)-dependent proteases, enhances the ligand sensitivity of both rod (CNGA1 and CNGB1) and cone (CNGA3 and CNGB3) CNG channels. Additionally, we have observed a decrease in the maximal CNG channel current (Imax) that begins late during MMP-directed gating changes. Here we demonstrate that CNG channels become nonconductive after prolonged MMP exposure. Concurrent with the loss of conductive channels is the increased relative contribution of channels exhibiting nonmodified gating properties, suggesting the presence of a subpopulation of channels that are protected from MMP-induced gating effects. CNGA subunits are known to possess one extracellular core glycosylation site, located at one of two possible positions within the turret loop near the pore-forming region. Our results indicate that CNGA glycosylation can impede MMP-dependent modification of CNG channels. Furthermore, the relative position of the glycosylation site within the pore turret influences the extent of MMP-dependent proteolysis. Glycosylation at the site found in CNGA3 subunits was found to be protective, while glycosylation at the bovine CNGA1 site was not. Relocating the glycosylation site in CNGA1 to the position found in CNGA3 recapitulated CNGA3-like protection from MMP-dependent processing. Taken together, these data indicate that CNGA glycosylation may protect CNG channels from MMP-dependent proteolysis, consistent with MMP modification of channel function having a requirement for physical access to the extracellular face of the channel.
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Affiliation(s)
- Starla E Meighan
- Program in Neuroscience, Department of Integrative Physiology and Neuroscience, ‡WWAMI Medical Education Program, and §Center for Integrated Biotechnology, Washington State University , P.O. Box 647620, Pullman, Washington 99164, United States
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