1
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Zhang J, Liu S, Fan J, Yan R, Huang B, Zhou F, Yuan T, Gong J, Huang Z, Jiang D. Structural basis of human Slo2.2 channel gating and modulation. Cell Rep 2023; 42:112858. [PMID: 37494189 DOI: 10.1016/j.celrep.2023.112858] [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: 12/15/2022] [Revised: 06/16/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023] Open
Abstract
The sodium-activated Slo2.2 channel is abundantly expressed in the brain, playing a critical role in regulating neuronal excitability. The Na+-binding site and the underlying mechanisms of Na+-dependent activation remain unclear. Here, we present cryoelectron microscopy (cryo-EM) structures of human Slo2.2 in closed, open, and inhibitor-bound form at resolutions of 2.6-3.2 Å, revealing gating mechanisms of Slo2.2 regulation by cations and a potent inhibitor. The cytoplasmic gating ring domain of the closed Slo2.2 harbors multiple K+ and Zn2+ sites, which stabilize the channel in the closed conformation. The open Slo2.2 structure reveals at least two Na+-sensitive sites where Na+ binding induces expansion and rotation of the gating ring that opens the inner gate. Furthermore, a potent inhibitor wedges into a pocket formed by pore helix and S6 helix and blocks the pore. Together, our results provide a comprehensive structural framework for the investigation of Slo2.2 channel gating, Na+ sensation, and inhibition.
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Affiliation(s)
- Jiangtao Zhang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shiqi Liu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Junping Fan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Rui Yan
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Bo Huang
- Beijing StoneWise Technology Co Ltd., Haidian District, Beijing, China
| | - Feng Zhou
- Beijing StoneWise Technology Co Ltd., Haidian District, Beijing, China
| | - Tian Yuan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Jianke Gong
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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2
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Qing R, Hao S, Smorodina E, Jin D, Zalevsky A, Zhang S. Protein Design: From the Aspect of Water Solubility and Stability. Chem Rev 2022; 122:14085-14179. [PMID: 35921495 PMCID: PMC9523718 DOI: 10.1021/acs.chemrev.1c00757] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Indexed: 12/13/2022]
Abstract
Water solubility and structural stability are key merits for proteins defined by the primary sequence and 3D-conformation. Their manipulation represents important aspects of the protein design field that relies on the accurate placement of amino acids and molecular interactions, guided by underlying physiochemical principles. Emulated designer proteins with well-defined properties both fuel the knowledge-base for more precise computational design models and are used in various biomedical and nanotechnological applications. The continuous developments in protein science, increasing computing power, new algorithms, and characterization techniques provide sophisticated toolkits for solubility design beyond guess work. In this review, we summarize recent advances in the protein design field with respect to water solubility and structural stability. After introducing fundamental design rules, we discuss the transmembrane protein solubilization and de novo transmembrane protein design. Traditional strategies to enhance protein solubility and structural stability are introduced. The designs of stable protein complexes and high-order assemblies are covered. Computational methodologies behind these endeavors, including structure prediction programs, machine learning algorithms, and specialty software dedicated to the evaluation of protein solubility and aggregation, are discussed. The findings and opportunities for Cryo-EM are presented. This review provides an overview of significant progress and prospects in accurate protein design for solubility and stability.
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Affiliation(s)
- Rui Qing
- State
Key Laboratory of Microbial Metabolism, School of Life Sciences and
Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- Media
Lab, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- The
David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Shilei Hao
- Media
Lab, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Key
Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, China
| | - Eva Smorodina
- Department
of Immunology, University of Oslo and Oslo
University Hospital, Oslo 0424, Norway
| | - David Jin
- Avalon GloboCare
Corp., Freehold, New Jersey 07728, United States
| | - Arthur Zalevsky
- Laboratory
of Bioinformatics Approaches in Combinatorial Chemistry and Biology, Shemyakin−Ovchinnikov Institute of Bioorganic
Chemistry RAS, Moscow 117997, Russia
| | - Shuguang Zhang
- Media
Lab, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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3
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TMAO to the rescue of pathogenic protein variants. Biochim Biophys Acta Gen Subj 2022; 1866:130214. [PMID: 35902028 DOI: 10.1016/j.bbagen.2022.130214] [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: 02/03/2022] [Revised: 07/11/2022] [Accepted: 07/21/2022] [Indexed: 11/22/2022]
Abstract
Trimethylamine N-oxide (TMAO) is a chemical chaperone found in various organisms including humans. Various studies unveiled that it is an excellent protein-stabilizing agent, and induces folding of unstructured proteins. It is also well established that it can counteract the deleterious effects of urea, salt, and hydrostatic pressure on macromolecular integrity. There is also existence of large body of data regarding its ability to restore functional deficiency of various mutant proteins or pathogenic variants by correcting misfolding defects and inhibiting the formation of high-order toxic protein oligomers. Since an important class of human disease called "protein conformational disorders" is due to protein misfolding and/or formation of high-order oligomers, TMAO stands as a promising molecule for the therapeutic intervention of such diseases. The present review has been designed to gather a comprehensive knowledge of the TMAO's effect on the functional restoration of various mutants, identify its shortcomings and explore its potentiality as a lead molecule. Future prospects have also been suitably incorporated.
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4
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do Canto AM, Donatti A, Geraldis JC, Godoi AB, da Rosa DC, Lopes-Cendes I. Neuroproteomics in Epilepsy: What Do We Know so Far? Front Mol Neurosci 2021; 13:604158. [PMID: 33488359 PMCID: PMC7817846 DOI: 10.3389/fnmol.2020.604158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/09/2020] [Indexed: 12/12/2022] Open
Abstract
Epilepsies are chronic neurological diseases that affect approximately 2% of the world population. In addition to being one of the most frequent neurological disorders, treatment for patients with epilepsy remains a challenge, because a proportion of patients do not respond to the antiseizure medications that are currently available. This results in a severe economic and social burden for patients, families, and the healthcare system. A characteristic common to all forms of epilepsy is the occurrence of epileptic seizures that are caused by abnormal neuronal discharges, leading to a clinical manifestation that is dependent on the affected brain region. It is generally accepted that an imbalance between neuronal excitation and inhibition generates the synchronic electrical activity leading to seizures. However, it is still unclear how a normal neural circuit becomes susceptible to the generation of seizures or how epileptogenesis is induced. Herein, we review the results of recent proteomic studies applied to investigate the underlying mechanisms leading to epilepsies and how these findings may impact research and treatment for these disorders.
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Affiliation(s)
- Amanda M. do Canto
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
| | - Amanda Donatti
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
| | - Jaqueline C. Geraldis
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
| | - Alexandre B. Godoi
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
| | - Douglas C. da Rosa
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
| | - Iscia Lopes-Cendes
- Department of Medical Genetics and Genomic Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil
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5
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Feng X, Liu W, Cao F, Wang Y, Zhang G, Chen ZH, Wu F. Overexpression of HvAKT1 improves drought tolerance in barley by regulating root ion homeostasis and ROS and NO signaling. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6587-6600. [PMID: 32766860 DOI: 10.1093/jxb/eraa354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/28/2020] [Indexed: 05/24/2023]
Abstract
Potassium (K+) is the major cationic inorganic nutrient utilized for osmotic regulation, cell growth, and enzyme activation in plants. Inwardly rectifying K+ channel 1 (AKT1) is the primary channel for root K+ uptake in plants, but the function of HvAKT1 in barley plants under drought stress has not been fully elucidated. In this study, we conducted evolutionary bioinformatics, biotechnological, electrophysiological, and biochemical assays to explore molecular mechanisms of HvAKT1 in response to drought in barley. The expression of HvAKT1 was significantly up-regulated by drought stress in the roots of XZ5-a drought-tolerant wild barley genotype. We isolated and functionally characterized the plasma membrane-localized HvAKT1 using Agrobacterium-mediated plant transformation and Barley stripe mosaic virus-induced gene silencing of HvAKT1 in barley. Evolutionary bioinformatics indicated that the K+ selective filter in AKT1 originated from streptophyte algae and is evolutionarily conserved in land plants. Silencing of HvAKT1 resulted in significantly decreased biomass and suppressed K+ uptake in root epidermal cells under drought treatment. Disruption of HvAKT1 decreased root H+ efflux, H+-ATPase activity, and nitric oxide (NO) synthesis, but increased hydrogen peroxide (H2O2) production in the roots under drought stress. Furthermore, we observed that overexpression of HvAKT1 improves K+ uptake and increases drought resistance in barley. Our results highlight the importance of HvAKT1 for root K+ uptake and its pleiotropic effects on root H+-ATPase, and H2O2 and NO in response to drought stress, providing new insights into the genetic basis of drought tolerance and K+ nutrition in barley.
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Affiliation(s)
- Xue Feng
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
| | - Wenxing Liu
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
| | - Fangbin Cao
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
- Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, China
| | - Yizhou Wang
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
| | - Guoping Zhang
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
| | - Zhong-Hua Chen
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Collaborative Innovation Center for Grain Industry, College of Agriculture, Yangtze University, Jingzhou, China
| | - Feibo Wu
- Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus, Zhejiang University, Hangzhou, China
- Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, China
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6
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Feng X, Liu W, Qiu C, Zeng F, Wang Y, Zhang G, Chen Z, Wu F. HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H + homoeostasis. PLANT BIOTECHNOLOGY JOURNAL 2020; 18:1683-1696. [PMID: 31917885 PMCID: PMC7336388 DOI: 10.1111/pbi.13332] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 12/27/2019] [Accepted: 01/05/2020] [Indexed: 05/18/2023]
Abstract
Plant K+ uptake typically consists low-affinity mechanisms mediated by Shaker K+ channels (AKT/KAT/KC) and high-affinity mechanisms regulated by HAK/KUP/KT transporters, which are extensively studied. However, the evolutionary and genetic roles of both K+ uptake mechanisms for drought tolerance are not fully explored in crops adapted to dryland agriculture. Here, we employed evolutionary bioinformatics, biotechnological and electrophysiological approaches to determine the role of two important K+ transporters HvAKT2 and HvHAK1 in drought tolerance in barley. HvAKT2 and HvHAK1 were cloned and functionally characterized using barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) in drought-tolerant wild barley XZ5 and agrobacterium-mediated gene transfer in the barley cultivar Golden Promise. The hallmarks of the K+ selective filters of AKT2 and HAK1 are both found in homologues from strepotophyte algae, and they are evolutionarily conserved in strepotophyte algae and land plants. HvAKT2 and HvHAK1 are both localized to the plasma membrane and have high selectivity to K+ and Rb+ over other tested cations. Overexpression of HvAKT2 and HvHAK1 enhanced K+ uptake and H+ homoeostasis leading to drought tolerance in these transgenic lines. Moreover, HvAKT2- and HvHAK1-overexpressing lines showed distinct response of K+ , H+ and Ca2+ fluxes across plasma membrane and production of nitric oxide and hydrogen peroxide in leaves as compared to the wild type and silenced lines. High- and low-affinity K+ uptake mechanisms and their coordination with H+ homoeostasis play essential roles in drought adaptation of wild barley. These findings can potentially facilitate future breeding programs for resilient cereal crops in a changing global climate.
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Affiliation(s)
- Xue Feng
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
- Jiangsu Co‐Innovation Center for Modern Production Technology of Grain CropsYangzhou UniversityYangzhouChina
| | - Wenxing Liu
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Cheng‐Wei Qiu
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
- Jiangsu Co‐Innovation Center for Modern Production Technology of Grain CropsYangzhou UniversityYangzhouChina
| | - Fanrong Zeng
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Yizhou Wang
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Guoping Zhang
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Zhong‐Hua Chen
- School of ScienceHawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
- Collaborative Innovation Center for Grain IndustryCollege of AgricultureYangtze UniversityJingzhouChina
| | - Feibo Wu
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
- Jiangsu Co‐Innovation Center for Modern Production Technology of Grain CropsYangzhou UniversityYangzhouChina
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7
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Ziegler GC, Röser C, Renner T, Hahn T, Ehlis AC, Weber H, Dempfle A, Walitza S, Jacob C, Romanos M, Fallgatter AJ, Reif A, Lesch KP. KCNJ6 variants modulate reward-related brain processes and impact executive functions in attention-deficit/hyperactivity disorder. Am J Med Genet B Neuropsychiatr Genet 2020; 183:247-257. [PMID: 31099984 DOI: 10.1002/ajmg.b.32734] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 04/04/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022]
Abstract
KCNJ6, encoding a potassium channel subunit, regulates the excitability of dopaminergic neurons and is expressed in attention-deficit/hyperactivity disorder (ADHD)-relevant brain regions. As a potential ADHD risk gene, KCNJ6, therefore, may contribute to the endophenotypic variation of the disorder. The impact of two SNPs, rs7275707 and rs6517442, both located in the transcriptional control region of KCNJ6, on reporter gene expression was explored in cultured cells. The KCNJ6 variants were then tested for association with ADHD and personality traits in a family-based sample (165 affected children) and an adult case-control sample (450 patients, 426 controls). Furthermore, the genotypic influence on performance in an n-back task and a cued continuous performance test (cCPT) was investigated by electroencephalography recordings. Finally, rs6517442 function was assessed by a reward anticipation paradigm using functional magnetic resonance imaging. Different haplotypes of rs7275707 and rs6517442 significantly influenced KCNJ6 gene expression proving their functional relevance on the molecular level. In the family-based children sample rs7275707 was associated with ADHD (p = .038). Moreover, rs7275707 showed association with the personality trait of Reward Dependence (p = .031). In the ADHD group, both rs7275707 and rs6517442 influenced the Go-centroid location in the cCPT and the N200 amplitude in the n-back task. Furthermore, ventral striatal activation was impacted by rs6517442 during reward anticipation. Our data indicate that functional variants of KCNJ6 influence brain activity during reward-related and executive processes supporting the view of a differential, age-dependent modulatory impact of dopamine-related brain processes in ADHD risk.
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Affiliation(s)
- Georg C Ziegler
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Christoph Röser
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Tobias Renner
- Department of Child and Adolescent Psychiatry, University of Tübingen, Tübingen, Germany
| | - Tim Hahn
- Department of Psychiatry and Psychotherapy, University of Münster, Münster, Germany
| | - Ann-Christine Ehlis
- Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| | - Heike Weber
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Astrid Dempfle
- Institute of Medical Biometry and Statistics, Christian Albrecht-University Kiel, Kiel, Germany
| | - Susanne Walitza
- Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Christian Jacob
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Psychiatry and Psychotherapy, Medius Hospital of Kirchheim, Kirchheim unter Teck, Germany
| | - Marcel Romanos
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Andreas J Fallgatter
- Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| | - Andreas Reif
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Psychiatry and Psychotherapy, University of Frankfurt, Frankfurt, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
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8
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Liu YD, Ma MY, Hu XB, Yan H, Zhang YK, Yang HX, Feng JH, Wang L, Zhang H, Zhang B, Li QB, Zhang JC, Kong QX. Brain Proteomic Profiling in Intractable Epilepsy Caused by TSC1 Truncating Mutations: A Small Sample Study. Front Neurol 2020; 11:475. [PMID: 32655475 PMCID: PMC7326032 DOI: 10.3389/fneur.2020.00475] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/30/2020] [Indexed: 01/01/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a genetic disease characterized by seizures, mental deficiency, and abnormalities of the skin, brain, kidney, heart, and lungs. TSC is inherited in an autosomal dominant manner and is caused by variations in either the TSC1 or TSC2 gene. TSC-related epilepsy (TRE) is the most prevalent and challenging clinical feature of TSC, and more than half of the patients have refractory epilepsy. In clinical practice, we found several patients of intractable epilepsy caused by TSC1 truncating mutations. To study the changes of protein expression in the brain, three cases of diseased brain tissue with TSC1 truncating mutation resected in intractable epilepsy operations and three cases of control brain tissue resected in craniocerebral trauma operations were collected to perform protein spectrum detection, and then the data-independent acquisition (DIA) workflow was used to analyze differentially expressed proteins. As a result, there were 55 up- and 55 down-regulated proteins found in the damaged brain tissue with TSC1 mutation compared to the control. Further bioinformatics analysis revealed that the differentially expressed proteins were mainly concentrated in the synaptic membrane between the patients with TSC and the control. Additionally, TSC1 truncating mutations may affect the pathway of amino acid metabolism. Our study provides a new idea to explore the brain damage mechanism caused by TSC1 mutations.
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Affiliation(s)
- Yi-Dan Liu
- Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Meng-Yu Ma
- Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xi-Bin Hu
- Department of Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Huan Yan
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Yan-Ke Zhang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Hao-Xiang Yang
- Clinical Medical College, Jining Medical University, Jining, China
| | - Jing-Hui Feng
- Clinical Medical College, Jining Medical University, Jining, China
| | - Lin Wang
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Hao Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Bin Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Qiu-Bo Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, China
| | - Jun-Chen Zhang
- Department of Neurosurgery, Affiliated Hospital of Jining Medical University, Jining, China
| | - Qing-Xia Kong
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China.,Institute of Epilepsy, Jining Medical University, Jining, China
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9
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Werner J, Arian J, Bernhardt I, Ryglewski S, Duch C. Differential localization of voltage-gated potassium channels during Drosophila metamorphosis. J Neurogenet 2020; 34:133-150. [PMID: 31997675 DOI: 10.1080/01677063.2020.1715972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Neuronal excitability is determined by the combination of different ion channels and their sub-neuronal localization. This study utilizes protein trap fly strains with endogenously tagged channels to analyze the spatial expression patterns of the four Shaker-related voltage-gated potassium channels, Kv1-4, in the larval, pupal, and adult Drosophila ventral nerve cord. We find that all four channels (Shaker, Kv1; Shab, Kv2; Shaw, Kv3; and Shal, Kv4) each show different spatial expression patterns in the Drosophila ventral nerve cord and are predominantly targeted to different sub-neuronal compartments. Shaker is abundantly expressed in axons, Shab also localizes to axons but mostly in commissures, Shaw expression is restricted to distinct parts of neuropils, and Shal is found somatodendritically, but also in axons of identified motoneurons. During early pupal life expression of all four Shaker-related channels is markedly decreased with an almost complete shutdown of expression at early pupal stage 5 (∼30% through metamorphosis). Re-expression of Kv1-4 channels at pupal stage 6 starts with abundant channel localization in neuronal somata, followed by channel targeting to the respective sub-neuronal compartments until late pupal life. The developmental time course of tagged Kv1-4 channel expression corresponds with previously published data on developmental changes in single neuron physiology, thus indicating that protein trap fly strains are a useful tool to analyze developmental regulation of potassium channel expression. Finally, we take advantage of the large diameter of the giant fiber (GF) interneuron to map channel expression onto the axon and axon terminals of an identified interneuron. Shaker, Shaw, and Shal but not Shab channels localize to the non-myelinated GF axonal membrane and axon terminals. This study constitutes a first step toward systematically analyzing sub-neuronal potassium channel localization in Drosophila. Functional implications as well as similarities and differences to Kv1-4 channel localization in mammalian neurons are discussed.
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Affiliation(s)
- Jan Werner
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jashar Arian
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ida Bernhardt
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Stefanie Ryglewski
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Carsten Duch
- Institute of Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
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10
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TrkA undergoes a tetramer-to-dimer conversion to open TrkH which enables changes in membrane potential. Nat Commun 2020; 11:547. [PMID: 31992706 PMCID: PMC6987127 DOI: 10.1038/s41467-019-14240-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 12/11/2019] [Indexed: 01/07/2023] Open
Abstract
TrkH is a bacterial ion channel implicated in K+ uptake and pH regulation. TrkH assembles with its regulatory protein, TrkA, which closes the channel when bound to ADP and opens it when bound to ATP. However, it is unknown how nucleotides control the gating of TrkH through TrkA. Here we report the structures of the TrkH-TrkA complex in the presence of ADP or ATP. TrkA forms a tetrameric ring when bound to ADP and constrains TrkH to a closed conformation. The TrkA ring splits into two TrkA dimers in the presence of ATP and releases the constraints on TrkH, resulting in an open channel conformation. Functional studies show that both the tetramer-to-dimer conversion of TrkA and the loss of constraints on TrkH are required for channel gating. In addition, deletion of TrkA in Escherichia coli depolarizes the cell, suggesting that the TrkH-TrkA complex couples changes in intracellular nucleotides to membrane potential.
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11
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Case Report on: Very Early Afterdepolarizations in HiPSC-Cardiomyocytes-An Artifact by Big Conductance Calcium Activated Potassium Current (I bk,Ca). Cells 2020; 9:cells9010253. [PMID: 31968557 PMCID: PMC7017352 DOI: 10.3390/cells9010253] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/16/2019] [Accepted: 01/15/2020] [Indexed: 12/21/2022] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent an unlimited source of human CMs that could be a standard tool in drug research. However, there is concern whether hiPSC-CMs express all cardiac ion channels at physiological level and whether they might express non-cardiac ion channels. In a control hiPSC line, we found large, “noisy” outward K+ currents, when we measured outward potassium currents in isolated hiPSC-CMs. Currents were sensitive to iberiotoxin, the selective blocker of big conductance Ca2+-activated K+ current (IBK,Ca). Seven of 16 individual differentiation batches showed a strong initial repolarization in the action potentials (AP) recorded from engineered heart tissue (EHT) followed by very early afterdepolarizations, sometimes even with consecutive oscillations. Iberiotoxin stopped oscillations and normalized AP shape, but had no effect in other EHTs without oscillations or in human left ventricular tissue (LV). Expression levels of the alpha-subunit (KCa1.1) of the BKCa correlated with the presence of oscillations in hiPSC-CMs and was not detectable in LV. Taken together, individual batches of hiPSC-CMs can express sarcolemmal ion channels that are otherwise not found in the human heart, resulting in oscillating afterdepolarizations in the AP. HiPSC-CMs should be screened for expression of non-cardiac ion channels before being applied to drug research.
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12
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Revealing the ultrastructure of the membrane pores of intact Serratia marcescens cells by atomic force microscopy. Heliyon 2019; 5:e02636. [PMID: 31692582 PMCID: PMC6806401 DOI: 10.1016/j.heliyon.2019.e02636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/19/2019] [Accepted: 10/08/2019] [Indexed: 11/24/2022] Open
Abstract
This study aimed to characterize the surface ultrastructure of intact Serratia marcescens cells under physiological conditions. Topographic information of membrane pores of the cells was obtained by atomic force microscope (AFM). Three types of membrane pores (CH-1-Pore A, CH-1-Pore B and CH-1-Pore C) were observed and the spatial arrangements of membrane-spanning subunits in membranes were defined. High-resolution images revealed that the doughnut-shaped structures of CH-1-Pore A and CH-1-Pore B were composed of six-to-eight and four transmembrane subunits. The inverted teepee-shaped structure of CH-1-Pore C was segmented into two transmembrane subunits straddling a single funnel-like pore. This study, to the best of authors' knowledge, represents the first direct characterization of the surface ultrastructure of the membrane pores of Serratia marcescens CH-1 cells at the nanometer scale and offers new prospects of mapping membrane pores on intact prokaryotic cells.
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13
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Aguilar C, Raina JB, Fôret S, Hayward DC, Lapeyre B, Bourne DG, Miller DJ. Transcriptomic analysis reveals protein homeostasis breakdown in the coral Acropora millepora during hypo-saline stress. BMC Genomics 2019; 20:148. [PMID: 30786881 PMCID: PMC6381741 DOI: 10.1186/s12864-019-5527-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 02/13/2019] [Indexed: 11/18/2022] Open
Abstract
Background Coral reefs can experience salinity fluctuations due to rainfall and runoff; these events can have major impacts on the corals and lead to bleaching and mortality. On the Great Barrier Reef (GBR), low salinity events, which occur during summer seasons and can involve salinity dropping ~ 10 PSU correlate with declines in coral cover, and these events are predicted to increase in frequency and severity under future climate change scenarios. In other marine invertebrates, exposure to low salinity causes increased expression of genes involved in proteolysis, responses to oxidative stress, and membrane transport, but the effects that changes in salinity have on corals have so far received only limited attention. To better understand the coral response to hypo-osmotic stress, here we investigated the transcriptomic response of the coral Acropora millepora in both adult and juvenile life stages to acute (1 h) and more prolonged (24 h) exposure to low salinity. Results Differential gene expression analysis revealed the involvement of both common and specific response mechanisms in Acropora. The general response to environmental stressors included up-regulation of genes involved in the mitigation of macromolecular and oxidative damage, while up-regulation of genes involved in amino acid metabolism and transport represent specific responses to salinity stress. Conclusions This study is the first comprehensive transcriptomic analysis of the coral response to low salinity stress and provides important insights into the likely consequences of heavy rainfall and runoff events on coral reefs. Electronic supplementary material The online version of this article (10.1186/s12864-019-5527-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Catalina Aguilar
- AIMS@JCU and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.,ARC Centre of Excellence for Coral Reef Studies and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.,Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine & Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida, 33149, USA.,Atlantic Oceanographic and Meteorological Laboratories (AOML), NOAA, 4301 Rickenbacker Causeway, Miami, Florida, 33149, USA
| | - Jean-Baptiste Raina
- AIMS@JCU and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.,Climate Change Cluster (C3), University of Technology, Sydney, NSW, 2007, Australia
| | - Sylvain Fôret
- ARC Centre of Excellence for Coral Reef Studies and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.,Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - David C Hayward
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Bruno Lapeyre
- Laboratoire d'excellence CORAIL, Centre de Recherches Insulaires et Observatoire de l'Environnement (CRIOBE), Moorea, B.P.1013, Papeete, French Polynesia
| | - David G Bourne
- AIMS@JCU and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.,Australian Institute of Marine Science, Townsville, Queensland, 4810, Australia.,College of Science and Engineering, James Cook University, Townsville, 4811, Australia
| | - David J Miller
- AIMS@JCU and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia. .,ARC Centre of Excellence for Coral Reef Studies and Department of Molecular and Cell Biology, James Cook University, Townsville, Queensland, 4811, Australia.
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14
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Koide M, Moshkforoush A, Tsoukias NM, Hill-Eubanks DC, Wellman GC, Nelson MT, Dabertrand F. The yin and yang of K V channels in cerebral small vessel pathologies. Microcirculation 2018; 25. [PMID: 29247493 DOI: 10.1111/micc.12436] [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] [Received: 11/29/2017] [Accepted: 12/08/2017] [Indexed: 12/14/2022]
Abstract
Cerebral SVDs encompass a group of genetic and sporadic pathological processes leading to brain lesions, cognitive decline, and stroke. There is no specific treatment for SVDs, which progress silently for years before becoming clinically symptomatic. Here, we examine parallels in the functional defects of PAs in CADASIL, a monogenic form of SVD, and in response to SAH, a common type of hemorrhagic stroke that also targets the brain microvasculature. Both animal models exhibit dysregulation of the voltage-gated potassium channel, KV 1, in arteriolar myocytes, an impairment that compromises responses to vasoactive stimuli and impacts CBF autoregulation and local dilatory responses to neuronal activity (NVC). However, the extent to which this channelopathy-like defect ultimately contributes to these pathologies is unknown. Combining experimental data with computational modeling, we describe the role of KV 1 channels in the regulation of myocyte membrane potential at rest and during the modest increase in extracellular potassium associated with NVC. We conclude that PA resting membrane potential and myogenic tone depend strongly on KV 1.2/1.5 channel density, and that reciprocal changes in KV channel density in CADASIL and SAH produce opposite effects on extracellular potassium-mediated dilation during NVC.
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Affiliation(s)
- Masayo Koide
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Arash Moshkforoush
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Nikolaos M Tsoukias
- Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | | | - George C Wellman
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA.,Institute of Cardiovascular Sciences, University of Manchester, Manchester, UK
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15
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Zhu P, Li J, Zhang L, Liang Z, Tang B, Liao WP, Yi YH, Su T. Development-related aberrations in Kv1.1 α-subunit exert disruptive effects on bioelectrical activities of neurons in a mouse model of fragile X syndrome. Prog Neuropsychopharmacol Biol Psychiatry 2018; 84:140-151. [PMID: 29481897 DOI: 10.1016/j.pnpbp.2018.02.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 02/22/2018] [Accepted: 02/22/2018] [Indexed: 10/18/2022]
Abstract
Kv1.1, a Shaker homologue potassium channel, plays a critical role in homeostatic regulation of neuronal excitability. Aberrations in the functional properties of Kv1.1 have been implicated in several neurological disorders featured by neuronal hyperexcitability. Fragile X syndrome (FXS), the most common form of inherited mental retardation, is characterized by hyperexcitability in neural network and intrinsic membrane properties. The Kv1.1 channel provides an intriguing mechanistic candidate for FXS. We investigated the development-related expression pattern of the Kv1.1 α-subunit by using a Fmr1 knockout (KO) mouse model of FXS. Markedly decreased protein expression of Kv1.1 was found in neonatal and adult stages when compared to age-matched wild-type (WT) mice. Immunohistochemical investigations supported the delayed development-related increases in Kv1.1 expression, especially in CA3 pyramidal neurons. By applying a Kv1.1-specific blocker, dendrotoxin-κ (DTX-κ), we isolated the Kv1.1-mediated currents in the CA3 pyramidal neurons. The isolated DTX-κ-sensitive current of neurons from KO mice exhibited decreased amplitude, lower threshold of activation, and faster recovery from inactivation. The equivalent reduction in potassium current in the WT neurons following application of the appropriate amount of DTX-κ reproduced the enhanced firing abilities of KO neurons, suggesting the Kv1.1 channel as a critical contributor to the hyperexcitability of KO neurons. The role of Kv1.1 in controlling neuronal discharges was further supported by the parallel developmental trajectories of Kv1.1 expression, current amplitude, and discharge impacts, with a significant correlation between the amplitude of Kv1.1-mediated currents and Kv1.1-blocking-induced firing enhancement. These data suggest that the expression of the Kv1.1 α-subunit has a profound pathological relevance to hyperexcitability in FXS, as well as implications for normal development, maintenance, and control of neuronal activities.
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Affiliation(s)
- Pingping Zhu
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China; Department of Neurology, Guangzhou Red Cross Hospital, Medical College, Jinan University, Guangzhou, China
| | - Jialing Li
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Liting Zhang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Zhanrong Liang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Bin Tang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Wei-Ping Liao
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Yong-Hong Yi
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Tao Su
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China.
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16
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Luo F, Zhou H. Clenbuterol reduces GABAergic transmission in prefrontal cortex layer 5/6 pyramidal neurons of juvenile rat via reducing action potentials firing frequency of GABAergic interneurons. J Neurochem 2017; 144:152-161. [DOI: 10.1111/jnc.14248] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 10/10/2017] [Accepted: 10/18/2017] [Indexed: 11/29/2022]
Affiliation(s)
- F. Luo
- Center for Neuropsychiatric Diseases; Institute of Life Science; Nanchang University; Nanchang China
- Department of Neuroscience; Yale University; New Haven CT USA
| | - H. Zhou
- Institute of Neurobiology & State Key Laboratory of Medical Neurobiology; Institutes of Brain Science; Fudan University; Shanghai China
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17
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Venom-derived peptides inhibiting Kir channels: Past, present, and future. Neuropharmacology 2017; 127:161-172. [PMID: 28716449 DOI: 10.1016/j.neuropharm.2017.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/05/2017] [Accepted: 07/13/2017] [Indexed: 12/17/2022]
Abstract
Inwardly rectifying K+ (Kir) channels play a significant role in vertebrate and invertebrate biology by regulating the movement of K+ ions involved in membrane transport and excitability. Yet unlike other ion channels including their ancestral K+-selective homologs, there are very few venom toxins known to target and inhibit Kir channels with the potency and selectivity found for the Ca2+-activated and voltage-gated K+ channel families. It is unclear whether this is simply due to a lack of discovery, or instead a consequence of the evolutionary processes that drive the development of venom components towards their targets based on a collective efficacy to 1) elicit pain for defensive purposes, 2) promote paralysis for prey capture, or 3) facilitate delivery of venom components into the circulation. The past two decades of venom screening has yielded three venom peptides with inhibitory activity towards mammalian Kir channels, including the discovery of tertiapin, a high-affinity pore blocker from the venom of the European honey bee Apis mellifera. Venomics and structure-based computational approaches represent exciting new frontiers for venom peptide development, where re-engineering peptide 'scaffolds' such as tertiapin may aid in the quest to expand the palette of potent and selective Kir channel blockers for future research and potentially new therapeutics. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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18
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Paeger L, Bardos V, Kloppenburg P. Transient voltage-activated K + currents in central antennal lobe neurons: cell type-specific functional properties. J Neurophysiol 2017; 117:2053-2064. [PMID: 28179480 PMCID: PMC5434483 DOI: 10.1152/jn.00685.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 02/07/2017] [Accepted: 02/07/2017] [Indexed: 02/01/2023] Open
Abstract
In this study we analyzed transient voltage-activated K+ currents (IA) of projection neurons and local interneurons in the antennal lobe of the cockroach Periplaneta americana The antennal lobe is the first synaptic processing station for olfactory information in insects. Local interneurons are crucial for computing olfactory information and form local synaptic connections exclusively in the antennal lobe, whereas a primary task of the projection neurons is the transfer of preprocessed olfactory information from the antennal lobe to higher order centers in the protocerebrum. The different physiological tasks of these neurons require specialized physiological and morphological neuronal phenotypes. We asked if and how the different physiological phenotypes are reflected in the functional properties of IA, which is crucial for shaping intrinsic electrophysiological properties of neurons. Whole cell patch-clamp recordings from adult male P. americana showed that all their central antennal lobe neurons can generate IA The current exhibited marked cell type-specific differences in voltage dependence of steady-state activation and inactivation, and differences in inactivation kinetics during sustained depolarization. Pharmacological experiments revealed that IA in all neuron types was partially blocked by α-dendrotoxin and phrixotoxin-2, which are considered blockers with specificity for Shaker- and Shal-type channels, respectively. These findings suggest that IA in each cell type is a mixed current generated by channels of both families. The functional role of IA was analyzed in experiments under current clamp, in which portions of IA were blocked by α-dendrotoxin or phrixotoxin-2. These experiments showed that IA contributes significantly to the intrinsic electrophysiological properties, such as the action potential waveform and membrane excitability.NEW & NOTEWORTHY In the insect olfactory system, projection neurons and local interneurons have task-specific electrophysiological and morphological phenotypes. Voltage-activated potassium channels play a crucial role in shaping functional properties of these neurons. This study revealed marked cell type-specific differences in the biophysical properties of transient voltage-activated potassium currents in central antennal lobe neurons.
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Affiliation(s)
- Lars Paeger
- Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Viktor Bardos
- Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Peter Kloppenburg
- Biocenter, Institute for Zoology, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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19
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Luo F, Zheng J, Sun X, Tang H. Inward rectifier K+ channel and T-type Ca2+ channel contribute to enhancement of GABAergic transmission induced by β1-adrenoceptor in the prefrontal cortex. Exp Neurol 2017; 288:51-61. [DOI: 10.1016/j.expneurol.2016.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/17/2016] [Accepted: 11/10/2016] [Indexed: 10/20/2022]
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20
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Amino Acid Properties of Trafficking Determinants in the Outer Pore-Forming Region of Kv1 Potassium Channels in Cell Lines. Cell Biochem Biophys 2017; 75:25-33. [PMID: 28054303 DOI: 10.1007/s12013-016-0779-9] [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: 12/15/2014] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
Abstract
Different classes of Kv1 potassium channels have different trafficking patterns despite having very similar amino acid sequences. Two amino acids responsible for these differences have been identified in the outer pore turret region of Kv1.1 and Kv1.4. Here we tested a series of substitutions at these two determinants on Kv1.4. All P506 substitutions tested resulted in a significant decrease in surface protein, total protein, and protein half-life, indicating that proline is required at 506 to stabilize protein conformation and increase trafficking to the cell surface. All K533 substitutions tested had no effect on total protein, suggesting that the lysine at 533 is not important for maintaining Kv1.4 protein conformation. However, a basic or long polar amino acid, such as K, R, or Q, at this position favored high surface protein and efficient trafficking of Kv1.4, whereas an acidic or short amino acid, such as D, E, S, L, N, or H, at this position induced partial high endoplasmic reticulum-retention. This intracellular retention was not due to protein misfolding. We propose that these four prolines and four lysines in a Kv1.4 homotetramer might provide a binding site for a putative endoplasmic reticulum-export molecule to ensure high cell surface protein expression of the channel.
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21
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Boraphech P, Suksabye P, Kulinfra N, Kongsang W, Thiravetyan P. Cleanup of trimethylamine (fishy odor) from contaminated air by various species of Sansevieria spp. and their leaf materials. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2016; 18:1002-1013. [PMID: 27294282 DOI: 10.1080/15226514.2016.1183569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Removal of trimethylamine (TMA) by 10 different living Sansevieria spp. and their dried leaf materials was studied. The results showed that living Sansevieria kirkii was the most effective plant while Sansevieria masoniana was the least effective in TMA removal. Two major pathways were involved in stomata opening and epicuticular wax on the leaf surface. In the presence of TMA, the stomata opening in Sansevieria spp. was induced, which enhanced TMA removal under light conditions. Dried leaf powders of Sansevieria spp. adsorbed TMA through their waxes. Therefore, both living and non-living Sansevieria spp. can be effectively used for removal of TMA.
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Affiliation(s)
- Phattara Boraphech
- a School of Bioresources and Technology, King Mongkut's University of Technology Thonburi , Bangkok , Thailand
| | - Parinda Suksabye
- b Department of Urban and Industrial Environment , Science and Technology Faculty, Suan Dusit Rajabhat University , Bangkok , Thailand
| | - Nipaporn Kulinfra
- b Department of Urban and Industrial Environment , Science and Technology Faculty, Suan Dusit Rajabhat University , Bangkok , Thailand
| | - Wascharangkoon Kongsang
- b Department of Urban and Industrial Environment , Science and Technology Faculty, Suan Dusit Rajabhat University , Bangkok , Thailand
| | - Paitip Thiravetyan
- a School of Bioresources and Technology, King Mongkut's University of Technology Thonburi , Bangkok , Thailand
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22
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The topogenic function of S4 promotes membrane insertion of the voltage-sensor domain in the KvAP channel. Biochem J 2016; 473:4361-4372. [PMID: 27694387 DOI: 10.1042/bcj20160746] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/20/2016] [Accepted: 09/30/2016] [Indexed: 11/17/2022]
Abstract
Voltage-dependent K+ (KV) channels control K+ permeability in response to shifts in the membrane potential. Voltage sensing in KV channels is mediated by the positively charged transmembrane domain S4. The best-characterized KV channel, KvAP, lacks the distinct hydrophilic region corresponding to the S3-S4 extracellular loop that is found in other K+ channels. In the present study, we evaluated the topogenic properties of the transmembrane regions within the voltage-sensing domain in KvAP. S3 had low membrane insertion activity, whereas S4 possessed a unique type-I signal anchor (SA-I) function, which enabled it to insert into the membrane by itself. S4 was also found to function as a stop-transfer signal for retention in the membrane. The length and structural nature of the extracellular S3-S4 loop affected the membrane insertion of S3 and S4, suggesting that S3 membrane insertion was dependent on S4. Replacement of charged residues within the transmembrane regions with residues of opposite charge revealed that Asp72 in S2 and Glu93 in S3 contributed to membrane insertion of S3 and S4, and increased the stability of S4 in the membrane. These results indicate that the SA-I function of S4, unique among K+ channels studied to date, promotes the insertion of S3 into the membrane, and that the charged residues essential for voltage sensing contribute to the membrane-insertion of the voltage sensor domain in KvAP.
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23
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Thayer DA, Yang SB, Jan YN, Jan LY. N-linked glycosylation of Kv1.2 voltage-gated potassium channel facilitates cell surface expression and enhances the stability of internalized channels. J Physiol 2016; 594:6701-6713. [PMID: 27377235 DOI: 10.1113/jp272394] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 06/09/2016] [Indexed: 01/20/2023] Open
Abstract
KEY POINTS Kv1.2 and related voltage-gated potassium channels have a highly conserved N-linked glycosylation site in the first extracellular loop, with complex glycosylation in COS-7 cells similar to endogenous Kv1.2 glycosylation in hippocampal neurons. COS-7 cells expressing Kv1.2 show a crucial role of this N-linked glycosylation in the forward trafficking of Kv1.2 to the cell membrane. Although both wild-type and non-glycosylated mutant Kv1.2 channels that have reached the cell membrane are internalized at a comparable rate, mutant channels are degraded at a faster rate. Treatment of wild-type Kv1.2 channels on the cell surface with glycosidase to remove sialic acids also results in the faster degradation of internalized channels. Glycosylation of Kv1.2 is important with respect to facilitating trafficking to the cell membrane and enhancing the stability of channels that have reached the cell membrane. ABSTRACT Studies in cultured hippocampal neurons and the COS-7 cell line demonstrate important roles for N-linked glycosylation of Kv1.2 channels in forward trafficking and protein degradation. Kv1.2 channels can contain complex N-linked glycans, which facilitate cell surface expression of the channels. Additionally, the protein stability of cell surface-expressed Kv1.2 channels is affected by glycosylation via differences in the degradation of internalized channels. The present study reveals the importance of N-linked complex glycosylation in boosting Kv1.2 channel density. Notably, sialic acids at the terminal sugar branches play an important role in dampening the degradation of Kv1.2 internalized from the cell membrane to promote its stability.
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Affiliation(s)
- Desiree A Thayer
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA.,Amunix, Mountain View, CA, USA
| | - Shi-Bing Yang
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA
| | - Lily Y Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA
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24
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Mitterauer B, Garvin AM, Dirnhofer R. The Sudden Infant Death Syndrome (SIDS): A Neuro-Molecular Hypothesis. Neuroscientist 2016. [DOI: 10.1177/107385840000600306] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Most of the children who die before age 1 in developed countries do so for unknown reasons, and these deaths are attributed to the sudden infant death syndrome (SIDS). Prospective cardiorespiratory monitoring of infants has revealed that SIDS victims have subtle differences in breathing and heartbeat patterns compared to controls. Because death must involve cardiorespiratory arrest, a straightforward explanation for SIDS is failure on the part of pacemaker neurons controlling the rhythmical processes of breathing or heartbeat. Genes coding for hyperpolarization-activated pacemaker cation channels have recently been isolated and are expressed in the heart and the brain. The authors propose that mutations in these genes and in other genes required for cardiorespiratory pacemaker activity will predispose an individual to SIDS during a window of vulnerability present in the first year of life. Furthermore, mutations in clock genes can alter a variety of rhythmical processes and may indirectly disturb cardiorespiratory function as well.
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Affiliation(s)
- Bernhard Mitterauer
- Institute of Forensic Neuropsychiatry, University of Salzburg, Ignaz-Harrerstrasse 79, 5020 Salzburg, Austria,
| | - Alex M. Garvin
- Department of Biochemistry, Biocentre, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
| | - Richard Dirnhofer
- Institute of Legal Medicine, University of Bern, Buhlstrasse 20, CH-3012 Bern, Switzerland
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Shi WL, Chen XL, Wang LX, Gong ZT, Li S, Li CL, Xie BB, Zhang W, Shi M, Li C, Zhang YZ, Song XY. Cellular and molecular insight into the inhibition of primary root growth of Arabidopsis induced by peptaibols, a class of linear peptide antibiotics mainly produced by Trichoderma spp. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:2191-205. [PMID: 26850879 PMCID: PMC4809282 DOI: 10.1093/jxb/erw023] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Trichoderma spp. are well known biocontrol agents that produce a variety of antibiotics. Peptaibols are a class of linear peptide antibiotics mainly produced by Trichoderma Alamethicin, the most studied peptaibol, is reported as toxic to plants at certain concentrations, while the mechanisms involved are unclear. We illustrated the toxic mechanisms of peptaibols by studying the growth-inhibitory effect of Trichokonin VI (TK VI), a peptaibol from Trichoderma longibrachiatum SMF2, on Arabidopsis primary roots. TK VI inhibited root growth by suppressing cell division and cell elongation, and disrupting root stem cell niche maintenance. TK VI increased auxin content and disrupted auxin response gradients in root tips. Further, we screened the Arabidopsis TK VI-resistant mutant tkr1. tkr1 harbors a point mutation in GORK, which encodes gated outwardly rectifying K(+)channel proteins. This mutation alleviated TK VI-induced suppression of K(+)efflux in roots, thereby stabilizing the auxin gradient. The tkr1 mutant also resisted the phytotoxicity of alamethicin. Our results indicate that GORK channels play a key role in peptaibol-plant interaction and that there is an inter-relationship between GORK channels and maintenance of auxin homeostasis. The cellular and molecular insight into the peptaibol-induced inhibition of plant root growth advances our understanding of Trichoderma-plant interactions.
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Affiliation(s)
- Wei-Ling Shi
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Li-Xia Wang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Zhi-Ting Gong
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Shuyu Li
- State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chun-Long Li
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan 250100, China
| | - Bin-Bin Xie
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Wei Zhang
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan 250100, China
| | - Mei Shi
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Chuanyou Li
- State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu-Zhong Zhang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
| | - Xiao-Yan Song
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research, Shandong University, Jinan 250100, China
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26
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Goyffon M, Saul F, Faure G. [Relationships between venomous function and innate immune function]. Biol Aujourdhui 2016; 209:195-210. [PMID: 26820828 DOI: 10.1051/jbio/2015018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Indexed: 06/05/2023]
Abstract
Venomous function is investigated in relation to innate immune function in two cases selected from scorpion venom and serpent venom. In the first case, structural analysis of scorpion toxins and defensins reveals a close interrelation between both functions (toxic and innate immune system function). In the second case, structural and functional studies of natural inhibitors of toxic snake venom phospholipases A2 reveal homology with components of the innate immune system, leading to a similar conclusion. Although there is a clear functional distinction between neurotoxins, which act by targeting membrane ion channels, and the circulating defensins which protect the organism from pathogens, the scorpion short toxins and defensins share a common protein folding scaffold with a conserved cysteine-stabilized alpha-beta motif of three disulfide bridges linking a short alpha helix and an antiparallel beta sheet. Genomic analysis suggests that these proteins share a common ancestor (long venom toxins were separated from an early gene family which gave rise to separate short toxin and defensin families). Furthermore, a scorpion toxin has been experimentally synthetized from an insect defensin, and an antibacterial scorpion peptide, androctonin (whose structure is similar to that of a cone snail venom toxin), was shown to have a similar high affinity for the postsynaptic acetylcholine receptor of Torpedo sp. Natural inhibitors of phospholipase A2 found in the blood of snakes are associated with the resistance of venomous snakes to their own highly neurotoxic venom proteins. Three classes of phospholipases A2 inhibitors (PLI-α, PLI-β, PLI-γ) have been identified. These inhibitors display diverse structural motifs related to innate immune proteins including carbohydrate recognition domains (CRD), leucine rich repeat domains (found in Toll-like receptors) and three finger domains, which clearly differentiate them from components of the adaptive immune system. Thus, in structure, function and phylogeny, venomous function in both vertebrates and invertebrates are clearly interrelated with innate immune function.
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Affiliation(s)
- Max Goyffon
- UMR CNRS 7245, Département RDDM, Muséum national d'Histoire naturelle, 57 rue Cuvier, 75005 Paris, France
| | - Frederick Saul
- Institut Pasteur, Plate-forme de Cristallographie, CNRS-UMR 3528, 25 rue du Docteur Roux, 75015 Paris, France
| | - Grazyna Faure
- Institut Pasteur, Unité Récepteurs-Canaux, CNRS-UMR 3571, 25 rue du Docteur Roux, 75015 Paris, France
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Clay JR. A Novel Method for the Description of Voltage-Gated Ionic Currents Based on Action Potential Clamp Results-Application to Hippocampal Mossy Fiber Boutons. Front Cell Neurosci 2016; 9:514. [PMID: 26793065 PMCID: PMC4710754 DOI: 10.3389/fncel.2015.00514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 12/21/2015] [Indexed: 11/13/2022] Open
Abstract
Action potential clamp (AP-clamp) recordings of the delayed rectifier K(+) current I K and the fast-activated Na(+) current I Na in rat hippocampal mossy fiber boutons (MFBs) are analyzed using a computational technique recently reported. The method is implemented using a digitized AP from an MFB and computationally applying that data set to published models of I K and I Na. These numerical results are compared with experimental AP-clamp recordings. The I Na result is consistent with experiment; the I K result is not. The difficulty with the I K model concerns the fully activated current-voltage relation, which is described here by the Goldman-Hodgkin-Katz dependence on the driving force (V-E K) rather than (V-E K) itself, the standard model for this aspect of ion permeation. That revision leads to the second-a much steeper voltage dependent activation curve for I K than the one obtained from normalization of a family of I K records by (V-E K). The revised model provides an improved description of the AP-clamp measurement of I K in MFBs compared with the standard approach. The method described here is general. It can be used to test models of ionic currents in any excitable cell. In this way it provides a novel approach to the relationship between ionic current and membrane excitability in neurons.
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Affiliation(s)
- John R Clay
- Department of Physiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health Rockville, MD, USA
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Zhang Y, Kong W, Gao Y, Liu X, Gao K, Xie H, Wu Y, Zhang Y, Wang J, Gao F, Wu X, Jiang Y. Gene Mutation Analysis in 253 Chinese Children with Unexplained Epilepsy and Intellectual/Developmental Disabilities. PLoS One 2015; 10:e0141782. [PMID: 26544041 PMCID: PMC4636363 DOI: 10.1371/journal.pone.0141782] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/13/2015] [Indexed: 12/18/2022] Open
Abstract
Objective Epilepsy and intellectual/developmental disabilities (ID/DD) have a high rate of co-occurrence. Here, we investigated gene mutations in Chinese children with unexplained epilepsy and ID/DD. Methods We used targeted next-generation sequencing to detect mutations within 300 genes related to epilepsy and ID/DD in 253 Chinese children with unexplained epilepsy and ID/DD. A series of filtering criteria was used to find the possible pathogenic variations. Validation and parental origin analyses were performed by Sanger sequencing. We reviewed the phenotypes of patients with each mutated gene. Results We identified 32 novel and 16 reported mutations within 24 genes in 46 patients. The detection rate was 18% (46/253) in the whole group and 26% (17/65) in the early-onset (before three months after birth) epilepsy group. To our knowledge, we are the first to report KCNAB1 is a disease-causing gene of epilepsy by identifying a novel de novo mutation (c.1062dupCA p.Leu355HisfsTer5) within this gene in one patient with early infantile epileptic encephalopathy (EIEE). Patients with an SCN1A mutation accounted for the largest proportion, 17% (8/46). A total of 38% (9/24) of the mutated genes re-occurred at least 2 times and 63% (15/24) occurred only one time. Ion channel genes are the most common (8/24) and genes related to synapse are the next most common to occur (5/24). Significance We have established genetic diagnosis for 46 patients of our cohort. Early-onset epilepsy had the highest detection rate. KCNAB1 mutation was first identified in EIEE patient. We expanded the phenotype and mutation spectrum of the genes we identified. The mutated genes in this cohort are mostly isolated. This suggests that epilepsy and ID/DD phenotypes occur as a consequence of brain dysfunction caused by a highly diverse population of mutated genes. Ion channel genes and genes related to synapse were more common mutated in this patient cohort.
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Affiliation(s)
- Yujia Zhang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
- Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
| | - Weijing Kong
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Yang Gao
- Department of Neurosurgery, the Second Hospital of Dalian Medical University, Dalian, China
| | - Xiaoyan Liu
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Kai Gao
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Han Xie
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Ye Wu
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Jingmin Wang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Feng Gao
- The Children’s Hospital, Zhejiang University School of Medicine, Zhejiang, China
| | - Xiru Wu
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Yuwu Jiang
- Department of Pediatrics and Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China
- Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
- * E-mail:
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Clinical heterogeneity associated with KCNA1 mutations include cataplexy and nonataxic presentations. Neurogenetics 2015; 17:11-6. [PMID: 26395884 DOI: 10.1007/s10048-015-0460-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/10/2015] [Indexed: 10/23/2022]
Abstract
Mutations in the KCNA1 gene are known to cause episodic ataxia/myokymia syndrome type 1 (EA1). Here, we describe two families with unique presentations who were enrolled in an IRB-approved study, extensively phenotyped, and whole exome sequencing (WES) performed. Family 1 had a diagnosis of isolated cataplexy triggered by sudden physical exertion in multiple affected individuals with heterogeneous neurological findings. All enrolled affected members carried a KCNA1 c.941T>C (p.I314T) mutation. Family 2 had an 8-year-old patient with muscle spasms with rigidity for whom WES revealed a previously reported heterozygous missense mutation in KCNA1 c.677C>G (p.T226R), confirming the diagnosis of EA1 without ataxia. WES identified variants in KCNA1 that explain both phenotypes expanding the phenotypic spectrum of diseases associated with mutations of this gene. KCNA1 mutations should be considered in patients of all ages with episodic neurological phenotypes, even when ataxia is not present. This is an example of the power of genomic approaches to identify pathogenic mutations in unsuspected genes responsible for heterogeneous diseases.
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30
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Boraphech P, Thiravetyan P. Removal of trimethylamine (fishy odor) by C₃ and CAM plants. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:11543-11557. [PMID: 25827651 DOI: 10.1007/s11356-015-4364-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/11/2015] [Indexed: 06/04/2023]
Abstract
From screening 23 plant species, it was found that Pterocarpus indicus (C3) and Sansevieria trifasciata (crassulacean acid metabolism (CAM)) were the most effective in polar gaseous trimethylamine (TMA) uptake, reaching up to 90% uptake of initial TMA (100 ppm) within 8 h, and could remove TMA at cycles 1-4 without affecting photosystem II (PSII) photochemistry. Up to 55 and 45% of TMA was taken up by S. trifasciata stomata and leaf epicuticular wax, respectively. During cycles 1-4, interestingly, S. trifasciata changed its stomata apertures, which was directly induced by gaseous TMA and light treatments. In contrast, for P. indicus the leaf epicuticular wax and stem were the major pathways of TMA removal, followed by stomata; these pathways accounted for 46, 46, and 8%, respectively, of TMA removal percentages. Fatty acids, particularly tetradecanoic (C14) acid and octadecanoic (C18) acid, were found to be the main cuticular wax components in both plants, and were associated with TMA removal ability. Moreover, the plants could degrade TMA via multiple metabolic pathways associated with carbon/nitrogen interactions. In CAM plants, one of the crucial pathways enabled 78% of TMA to be transformed directly to dimethylamine (DMA) and methylamine (MA), which differed from C3 plant pathways. Various metabolites were also produced for further detoxification and mineralization so that TMA was completely degraded by plants.
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Affiliation(s)
- Phattara Boraphech
- School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand
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31
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A structural model for facultative anion channels in an oligomeric membrane protein: the yeast TRK (K+) system. Pflugers Arch 2015; 467:2447-60. [DOI: 10.1007/s00424-015-1712-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 12/16/2022]
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Fohlmeister JF. Voltage gating by molecular subunits of Na+ and K+ ion channels: higher-dimensional cubic kinetics, rate constants, and temperature. J Neurophysiol 2015; 113:3759-77. [PMID: 25867741 DOI: 10.1152/jn.00551.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 03/25/2015] [Indexed: 11/22/2022] Open
Abstract
The structural similarity between the primary molecules of voltage-gated Na and K channels (alpha subunits) and activation gating in the Hodgkin-Huxley model is brought into full agreement by increasing the model's sodium kinetics to fourth order (m(3) → m(4)). Both structures then virtually imply activation gating by four independent subprocesses acting in parallel. The kinetics coalesce in four-dimensional (4D) cubic diagrams (16 states, 32 reversible transitions) that show the structure to be highly failure resistant against significant partial loss of gating function. Rate constants, as fitted in phase plot data of retinal ganglion cell excitation, reflect the molecular nature of the gating transitions. Additional dimensions (6D cubic diagrams) accommodate kinetically coupled sodium inactivation and gating processes associated with beta subunits. The gating transitions of coupled sodium inactivation appear to be thermodynamically irreversible; response to dielectric surface charges (capacitive displacement) provides a potential energy source for those transitions and yields highly energy-efficient excitation. A comparison of temperature responses of the squid giant axon (apparently Arrhenius) and mammalian channel gating yields kinetic Q10 = 2.2 for alpha unit gating, whose transitions are rate-limiting at mammalian temperatures; beta unit kinetic Q10 = 14 reproduces the observed non-Arrhenius deviation of mammalian gating at low temperatures; the Q10 of sodium inactivation gating matches the rate-limiting component of activation gating at all temperatures. The model kinetics reproduce the physiologically large frequency range for repetitive firing in ganglion cells and the physiologically observed strong temperature dependence of recovery from inactivation.
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Affiliation(s)
- Jürgen F Fohlmeister
- Department of Integrative Biology and Physiology and Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Bittsánszky A, Pilinszky K, Gyulai G, Komives T. Overcoming ammonium toxicity. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 231:184-90. [PMID: 25576003 DOI: 10.1016/j.plantsci.2014.12.005] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 12/05/2014] [Accepted: 12/06/2014] [Indexed: 05/20/2023]
Abstract
Ammonia (ammonium ion under physiological conditions) is one of the key nitrogen sources in cellular amino acid biosynthesis. It is continuously produced in living organisms by a number of biochemical processes, but its accumulation in cells leads to tissue damage. Current knowledge suggests that a few enzymes and transporters are responsible for maintaining the delicate balance of ammonium fluxes in plant tissues. In this study we analyze the data in the scientific literature and the publicly available information on the dozens of biochemical reactions in which endogenous ammonium is produced or consumed, the enzymes that catalyze them, and the enzyme and transporter mutants listed in plant metabolic and genetic databases (Plant Metabolic Network, TAIR, and Genevestigator). Our compiled data show a surprisingly high number of little-studied reactions that might influence cellular ammonium concentrations. The role of ammonium in apoptosis, its relation to oxidative stress, and alterations in ammonium metabolism induced by environmental stress need to be explored in order to develop methods to manage ammonium toxicity.
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Affiliation(s)
- András Bittsánszky
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary
| | - Katalin Pilinszky
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary
| | - Gábor Gyulai
- Department of Genetics and Plant Breeding, Szent István University, Páter K. 1, 2103 Gödöllő, Hungary
| | - Tamas Komives
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary.
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Venglovecz V, Rakonczay Z, Gray MA, Hegyi P. Potassium channels in pancreatic duct epithelial cells: their role, function and pathophysiological relevance. Pflugers Arch 2014; 467:625-40. [PMID: 25074489 DOI: 10.1007/s00424-014-1585-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/09/2014] [Accepted: 07/18/2014] [Indexed: 12/14/2022]
Abstract
Pancreatic ductal epithelial cells play a fundamental role in HCO3 (-) secretion, a process which is essential for maintaining the integrity of the pancreas. Although several studies have implicated impaired HCO3 (-) and fluid secretion as a triggering factor in the development of pancreatitis, the mechanism and regulation of HCO3 (-) secretion is still not completely understood. To date, most studies on the ion transporters that orchestrate ductal HCO3 (-) secretion have focussed on the role of Cl(-)/HCO3 (-) exchangers and Cl(-) channels, whereas much less is known about the role of K(+) channels. However, there is growing evidence that many types of K(+) channels are present in ductal cells where they have an essential role in establishing and maintaining the electrochemical driving force for anion secretion. For this reason, strategies that increase K(+) channel function may help to restore impaired HCO3 (-) and fluid secretion, such as in pancreatitis, and therefore provide novel directions for future pancreatic therapy. In this review, our aims are to summarize the types of K(+) channels found in pancreatic ductal cells and to discuss their individual roles in ductal HCO3 (-) secretion. We will also describe how K(+) channels are involved in pathophysiological conditions and discuss how they could act as new molecular targets for the development of therapeutic approaches to treat pancreatic diseases.
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Affiliation(s)
- Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary,
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Garcia K, Zimmermann SD. The role of mycorrhizal associations in plant potassium nutrition. FRONTIERS IN PLANT SCIENCE 2014; 5:337. [PMID: 25101097 PMCID: PMC4101882 DOI: 10.3389/fpls.2014.00337] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/25/2014] [Indexed: 05/05/2023]
Abstract
Potassium (K(+)) is one of the most abundant elements of soil composition but it's very low availability limits plant growth and productivity of ecosystems. Because this cation participates in many biological processes, its constitutive uptake from soil solution is crucial for the plant cell machinery. Thus, the understanding of strategies responsible of K(+) nutrition is a major issue in plant science. Mycorrhizal associations occurring between roots and hyphae of underground fungi improve hydro-mineral nutrition of the majority of terrestrial plants. The contribution of this mutualistic symbiosis to the enhancement of plant K(+) nutrition is not well understood and poorly studied so far. This mini-review examines the current knowledge about the impact of both arbuscular mycorrhizal and ectomycorrhizal symbioses on the transfer of K(+) from the soil to the plants. A model summarizing plant and fungal transport systems identified and hypothetically involved in K(+) transport is proposed. In addition, some data related to benefits for plants provided by the improvement of K(+) nutrition thanks to mycorrhizal symbioses are presented.
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Affiliation(s)
| | - Sabine D. Zimmermann
- Biochimie et Physiologie Moléculaire des Plantes, UMR 5004 CNRS/INRA/SupAgro/UM2Montpellier, France
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36
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Lassche S, Lainez S, Bloem BR, van de Warrenburg BP, Hofmeijer J, Lemmink HH, Hoenderop JG, Bindels RJ, Drost G. A novel KCNA1
mutation causing episodic ataxia type I. Muscle Nerve 2014; 50:289-91. [DOI: 10.1002/mus.24242] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/24/2014] [Accepted: 03/13/2014] [Indexed: 01/09/2023]
Affiliation(s)
- Saskia Lassche
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center; Nijmegen The Netherlands
| | - Sergio Lainez
- Department of Physiology; Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center; Nijmegen The Netherlands
- Department of Pharmacolgy; University of Cambridge; Cambridge UK
| | - Bastiaan R. Bloem
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center; Nijmegen The Netherlands
| | - Bart P.C. van de Warrenburg
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center; Nijmegen The Netherlands
| | - Jeannette Hofmeijer
- Clinical Neurophysiology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente; Enschede The Netherlands
| | - Henny H. Lemmink
- Department of Genetics; University Medical Centre Groningen; Groningen The Netherlands
| | - Joost G.J. Hoenderop
- Department of Physiology; Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center; Nijmegen The Netherlands
| | - René J.M. Bindels
- Department of Physiology; Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Center; Nijmegen The Netherlands
| | - Gea Drost
- Department of Neurology and Department of Neurosurgery; University Medical Centre Groningen, University of Groningen; P.O. Box 30.001 9700 RB Groningen The Netherlands
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Levin EJ, Zhou M. Recent progress on the structure and function of the TrkH/KtrB ion channel. Curr Opin Struct Biol 2014; 27:95-101. [PMID: 25011047 DOI: 10.1016/j.sbi.2014.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Members of the Superfamily of K(+) Transporters (SKT) are integral membrane proteins that mediate the uptake of ions into non-animal cells. Although these proteins are homologous to the well-characterized K(+) channel family, relatively little was known about their transport and gating mechanisms until the recent determination of crystal structures for two SKT proteins, TrkH and KtrB. These structures reveal that the SKT proteins are channels, containing a flexible loop in the middle of the permeation pathway that may act as a gate. Two different conformational changes have been observed for the associated gating rings, suggesting different mechanisms of regulation by the binding of nucleotides.
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Affiliation(s)
- Elena J Levin
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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38
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Large conductance Ca2+-activated K+ channel (BKCa) α-subunit splice variants in resistance arteries from rat cerebral and skeletal muscle vasculature. PLoS One 2014; 9:e98863. [PMID: 24921651 PMCID: PMC4055454 DOI: 10.1371/journal.pone.0098863] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 05/07/2014] [Indexed: 11/19/2022] Open
Abstract
Previous studies report functional differences in large conductance Ca2+ activated-K+ channels (BKCa) of smooth muscle cells (VSMC) from rat cerebral and cremaster muscle resistance arteries. The present studies aimed to determine if this complexity in BKCa activity may, in part, be due to splice variants in the pore-forming α-subunit. BKCa variants in the intracellular C terminus of the α-subunit, and their relative expression to total α-subunit, were examined by qPCR. Sequencing of RT-PCR products showed two α-subunit variants, ZERO and STREX, to be identical in cremaster and cerebral arteries. Levels of STREX mRNA expression were, however, significantly higher in cremaster VSMCs (28.9±4.2% of total α-BKCa) compared with cerebral vessels (16.5±0.9%). Further, a low level of BKCa SS4 α-subunit variant was seen in cerebral arteries, while undetectable in cremaster arteries. Protein biotinylation assays, in expression systems and arterial preparations, were used to determine whether differences in splice variant mRNA expression affect surface membrane/cytosolic location of the channel. In AD-293 and CHO-K1 cells, rat STREX was more likely to be located at the plasma membrane compared to ZERO, although the great majority of channel protein was in the membrane in both cases. Co-expression of β1-BKCa subunit with STREX or ZERO did not influence the dominant membrane expression of α-BKCa subunits, whereas in the absence of α-BKCa, a significant proportion of β1-subunit remained cytosolic. Biotinylation assays of cremaster and cerebral arteries showed that differences in STREX/ZERO expression do not alter membrane/cytosolic distribution of the channel under basal conditions. These data, however, revealed that the amount of α-BKCa in cerebral arteries is approximately 20X higher than in cremaster vessels. Thus, the data support the major functional differences in BKCa activity in cremaster, as compared to cerebral VSMCs, being related to total α-BKCa expression, regardless of differences in splice variant expression.
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Anschütz U, Becker D, Shabala S. Going beyond nutrition: regulation of potassium homoeostasis as a common denominator of plant adaptive responses to environment. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:670-87. [PMID: 24635902 DOI: 10.1016/j.jplph.2014.01.009] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/14/2014] [Accepted: 01/17/2014] [Indexed: 05/18/2023]
Abstract
Partially and fully completed plant genome sequencing projects in both lower and higher plants allow drawing a comprehensive picture of the molecular and structural diversities of plant potassium transporter genes and their encoded proteins. While the early focus of the research in this field was aimed on the structure-function studies and understanding of the molecular mechanisms underlying K(+) transport, availability of Arabidopsis thaliana mutant collections in combination with micro-array techniques have significantly advanced our understanding of K(+) channel physiology, providing novel insights into the transcriptional regulation of potassium homeostasis in plants. More recently, posttranslational regulation of potassium transport systems has moved into the center stage of potassium transport research. The current review is focused on the most exciting developments in this field. By summarizing recent work on potassium transporter regulation we show that potassium transport in general, and potassium channels in particular, represent important targets and are mediators of the cellular responses during different developmental stages in a plant's life cycle. We show that regulation of intracellular K(+) homeostasis is essential to mediate plant adaptive responses to a broad range of abiotic and biotic stresses including drought, salinity, and oxidative stress. We further link post-translational regulation of K(+) channels with programmed cell death and show that K(+) plays a critical role in controlling the latter process. Thus, is appears that K(+) is not just the essential nutrient required to support optimal plant growth and yield but is also an important signaling agent mediating a wide range of plant adaptive responses to environment.
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Affiliation(s)
- Uta Anschütz
- University of Wuerzburg, Plant Molecular Biology & Biophysics, Wuerzburg, Germany
| | - Dirk Becker
- University of Wuerzburg, Plant Molecular Biology & Biophysics, Wuerzburg, Germany.
| | - Sergey Shabala
- School of Agricultural Science, University of Tasmania, Hobart, Australia
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Tinker A, Harmer SC. K+channels in the heart: new insights and therapeutic implications. Expert Rev Clin Pharmacol 2014; 3:305-19. [DOI: 10.1586/ecp.10.14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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García del Caño G, Montaña M, Aretxabala X, González-Burguera I, López de Jesús M, Barrondo S, Sallés J. Nuclear phospholipase C-β1 and diacylglycerol LIPASE-α in brain cortical neurons. Adv Biol Regul 2014; 54:12-23. [PMID: 24076015 DOI: 10.1016/j.jbior.2013.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 09/03/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
Phosphoinositide (PtdIns) signaling involves the generation of lipid second messengers in response to stimuli in a receptor-mediated manner at the plasma membrane. In neuronal cells of adult brain, the standard model proposes that activation of metabotropic receptors coupled to Phospholipase C-β1 (PLC-β1) is linked to endocannabinoid signaling through the production of diacylglycerol (DAG), which could be systematically metabolized by 1,2-diacylglycerol Lipases (DAGL) to produce an increase of 2-arachidonoyl-glycerol (2-AG), the most abundant endocannabinoid in the brain. However, the existence of a nuclear PtdIns metabolism independent from that occurring elsewhere in the cell is now widely accepted, suggesting that the nucleus constitutes both a functional and a distinct compartment for PtdIns metabolism. In this review, we shall highlight the main achievements in the field of neuronal nuclear inositol lipid metabolism with particular attention to progress made linked to the 2-AG biosynthesis. Our aim has been to identify potential sites of 2-AG synthesis other than the neuronal cytoplasmic compartment by determining the subcellular localization of PLC-β1 and DAGL-α, which is much more abundant than DAGL-β in brain. Our data show that PLC-β1 and DAGL-α are detected in discrete brain regions, with a marked predominance of pyramidal morphologies of positive cortical cells, consistent with their role in the biosynthesis and release of 2-AG by pyramidal neurons to control their synaptic inputs. However, as novelty, we showed here an integrated description of the localization of PLC-β1 and DAGL-α in the neuronal nuclear compartment. We discuss our comparative analysis of the expression patterns of PLC-β1 and DAGL-α, providing some insight into the potential autocrine role of 2-AG production in the neuronal nuclear compartment that probably subserve additional roles to the recognized activation of the CB1 cannabinoid receptor.
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Affiliation(s)
- Gontzal García del Caño
- Departamento de Neurociencias, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain
| | - Mario Montaña
- Departamento de Farmacología, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain; CIBERSAM, Spain
| | - Xabier Aretxabala
- Departamento de Neurociencias, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain
| | - Imanol González-Burguera
- Departamento de Farmacología, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain
| | - Maider López de Jesús
- Departamento de Farmacología, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain; CIBERSAM, Spain
| | - Sergio Barrondo
- Departamento de Farmacología, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain; CIBERSAM, Spain
| | - Joan Sallés
- Departamento de Farmacología, Facultad de Farmacia (Vitoria-Gasteiz), Universidad del País Vasco (UPV/EHU), Spain; CIBERSAM, Spain.
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Isacoff EY, Jan LY, Minor DL. Conduits of life's spark: a perspective on ion channel research since the birth of neuron. Neuron 2013; 80:658-74. [PMID: 24183018 DOI: 10.1016/j.neuron.2013.10.040] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Heartbeats, muscle twitches, and lightning-fast thoughts are all manifestations of bioelectricity and rely on the activity of a class of membrane proteins known as ion channels. The basic function of an ion channel can be distilled into, "The hole opens. Ions go through. The hole closes." Studies of the fundamental mechanisms by which this process happens and the consequences of such activity in the setting of excitable cells remains the central focus of much of the field. One might wonder after so many years of detailed poking at such a seemingly simple process, is there anything left to learn?
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Affiliation(s)
- Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Takahashi K, Naruse K. Stretch-activated BK channel and heart function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 110:239-44. [PMID: 23281538 DOI: 10.1016/j.pbiomolbio.2012.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The heart is an organ that is exposed to extreme dynamic mechanical stimuli. From birth till death, the heart indefinitely repeats periodic contraction and dilation, i.e., shortening and elongation of cardiomyocytes. Mechanical stretch elicits a change in heart rate and may cause arrhythmia if it is excessive. Thus, mechanosensitivity is crucial to heart function. The molecule that is substantially involved in mechanosensitivity is a stretch-activated ion channel. Among several ion channels believed to be activated by stretch in the heart, the stretch-activated KCa (SAKCA) channel, a member of the group of large conductance (Big Potassium, BK) channels, shows a mechanosensitive (MS) response to membrane stretch. As BK channels respond to voltage and intracellular calcium concentration with large conductance, they are considered to be involved in repolarization after depolarization. Some BK channels are known to be activated by stretch and are expressed in a number of cells, including human osteoblasts and guinea pig intestinal neurons. The SAKCA channel was found to be sensitive to stretch in the chick heart. Given that the cardiomyocyte is unremittingly exposed to contraction and dilation and that it generates action potential and its contractility is modulated by intracellular calcium concentration, the SAKCA channel, which is dependent voltage and calcium, may be involved in action potential generation. It was recently reported that a BK channel is involved in the modulation of heart rate in the mouse. Further studies regarding the role of MS BK channels, including SAKCA, in the modulation of heart rate and contractility are expected.
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Affiliation(s)
- Ken Takahashi
- Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
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Casieri L, Ait Lahmidi N, Doidy J, Veneault-Fourrey C, Migeon A, Bonneau L, Courty PE, Garcia K, Charbonnier M, Delteil A, Brun A, Zimmermann S, Plassard C, Wipf D. Biotrophic transportome in mutualistic plant-fungal interactions. MYCORRHIZA 2013; 23:597-625. [PMID: 23572325 DOI: 10.1007/s00572-013-0496-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/13/2013] [Indexed: 05/08/2023]
Abstract
Understanding the mechanisms that underlie nutrient use efficiency and carbon allocation along with mycorrhizal interactions is critical for managing croplands and forests soundly. Indeed, nutrient availability, uptake and exchange in biotrophic interactions drive plant growth and modulate biomass allocation. These parameters are crucial for plant yield, a major issue in the context of high biomass production. Transport processes across the polarized membrane interfaces are of major importance in the functioning of the established mycorrhizal association as the symbiotic relationship is based on a 'fair trade' between the fungus and the host plant. Nutrient and/or metabolite uptake and exchanges, at biotrophic interfaces, are controlled by membrane transporters whose regulation patterns are essential for determining the outcome of plant-fungus interactions and adapting to changes in soil nutrient quantity and/or quality. In the present review, we summarize the current state of the art regarding transport systems in the two major forms of mycorrhiza, namely ecto- and arbuscular mycorrhiza.
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Affiliation(s)
- Leonardo Casieri
- UMR Agroécologie INRA 1347/Agrosup/Université de Bourgogne, Pôle Interactions Plantes Microorganismes ERL 6300 CNRS, BP 86510, 21065, Dijon Cedex, France,
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Waszkielewicz AM, Gunia A, Szkaradek N, Słoczyńska K, Krupińska S, Marona H. Ion channels as drug targets in central nervous system disorders. Curr Med Chem 2013; 20:1241-85. [PMID: 23409712 PMCID: PMC3706965 DOI: 10.2174/0929867311320100005] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 01/14/2013] [Accepted: 01/18/2013] [Indexed: 12/27/2022]
Abstract
Ion channel targeted drugs have always been related with either the central nervous system (CNS), the peripheral nervous system, or the cardiovascular system. Within the CNS, basic indications of drugs are: sleep disorders, anxiety, epilepsy, pain, etc. However, traditional channel blockers have multiple adverse events, mainly due to low specificity of mechanism of action. Lately, novel ion channel subtypes have been discovered, which gives premises to drug discovery process led towards specific channel subtypes. An example is Na(+) channels, whose subtypes 1.3 and 1.7-1.9 are responsible for pain, and 1.1 and 1.2 - for epilepsy. Moreover, new drug candidates have been recognized. This review is focusing on ion channels subtypes, which play a significant role in current drug discovery and development process. The knowledge on channel subtypes has developed rapidly, giving new nomenclatures of ion channels. For example, Ca(2+)s channels are not any more divided to T, L, N, P/Q, and R, but they are described as Ca(v)1.1-Ca(v)3.3, with even newer nomenclature α1A-α1I and α1S. Moreover, new channels such as P2X1-P2X7, as well as TRPA1-TRPV1 have been discovered, giving premises for new types of analgesic drugs.
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Affiliation(s)
- A M Waszkielewicz
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Street, 30-688 Krakow, Poland.
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Abstract
Ion channels are integral membrane proteins that allow the flow of ions across membranes down their electrochemical gradients and are a major determinant of cellular excitability. They play an important role in a variety of biological processes as diverse as insulin release from beta cells in the pancreas through to cardiac and smooth muscle contraction. We have used total internal reflection fluorescence (TIRF) microscopy to watch ion channels being transported in vesicles along microtubules within the cytoplasm of the cell. Furthermore, we can directly observe the fusion of these vesicles with the plasma membrane and the release and radial dispersion of single ion channels into the membrane. Finally, automated single-particle tracking of these objects allowed us to determine their diffusional behavior.
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Zhong YS, Wang J, Liu WM, Zhu YH. Potassium ion channels in retinal ganglion cells (review). Mol Med Rep 2013; 8:311-9. [PMID: 23732984 DOI: 10.3892/mmr.2013.1508] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 05/22/2013] [Indexed: 11/06/2022] Open
Abstract
Retinal ganglion cells (RGCs) consolidate visual processing and constitute the last step prior to the transmission of signals to higher brain centers. RGC death is a major cause of visual impairment in optic neuropathies, including glaucoma, age‑related macular degeneration, diabetic retinopathy, uveoretinitis and vitreoretinopathy. Discharge patterns of RGCs are primarily determined by the presence of ion channels. As the most diverse group of ion channels, potassium (K+) channels play key roles in modulating the electrical properties of RGCs. Biochemical, molecular and pharmacological studies have identified a number of K+ channels in RGCs, including inwardly rectifying K+ (Kir), ATP‑sensitive K+ (KATP), tandem‑pore domain K+ (TASK), voltage‑gated K+ (Kv), ether‑à‑go‑go (Eag) and Ca2+‑activated K+ (KCa) channels. Kir channels are important in the maintenance of the resting membrane potential and controlling RGC excitability. KATP channels are involved in RGC survival and neuroprotection. TASK channels are hypothesized to contribute to the regulation of resting membrane potentials and firing patterns of RGCs. Kv channels are important regulators of cellular excitability, functioning to modulate the amplitude, duration and frequency of action potentials and subthreshold depolarizations, and are also important in RGC development and protection. Eag channels may contribute to dendritic repolarization during excitatory postsynaptic potentials and to the attenuation of the back propagation of action potentials. KCa channels have been observed to contribute to repetitive firing in RGCs. Considering these important roles of K+ channels in RGCs, the study of K+ channels may be beneficial in elucidating the pathophysiology of RGCs and exploring novel RGC protection strategies.
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Affiliation(s)
- Yi-Sheng Zhong
- Department of Ophthalmology, Ruijin Hospital Affiliated Medical School, Shanghai Jiaotong University, Shanghai 200025, P.R. China
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Barry J, Xu M, Gu Y, Dangel AW, Jukkola P, Shrestha C, Gu C. Activation of conventional kinesin motors in clusters by Shaw voltage-gated K+ channels. J Cell Sci 2013; 126:2027-41. [PMID: 23487040 DOI: 10.1242/jcs.122234] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The conventional kinesin motor transports many different cargos to specific locations in neurons. How cargos regulate motor function remains unclear. Here we focus on KIF5, the heavy chain of conventional kinesin, and report that the Kv3 (Shaw) voltage-gated K(+) channel, the only known tetrameric KIF5-binding protein, clusters and activates KIF5 motors during axonal transport. Endogenous KIF5 often forms clusters along axons, suggesting a potential role of KIF5-binding proteins. Our biochemical assays reveal that the high-affinity multimeric binding between the Kv3.1 T1 domain and KIF5B requires three basic residues in the KIF5B tail. Kv3.1 T1 competes with the motor domain and microtubules, but not with kinesin light chain 1 (KLC1), for binding to the KIF5B tail. Live-cell imaging assays show that four KIF5-binding proteins, Kv3.1, KLC1 and two synaptic proteins SNAP25 and VAMP2, differ in how they regulate KIF5B distribution. Only Kv3.1 markedly increases the frequency and number of KIF5B-YFP anterograde puncta. Deletion of Kv3.1 channels reduces KIF5 clusters in mouse cerebellar neurons. Therefore, clustering and activation of KIF5 motors by Kv3 regulate the motor number in carrier vesicles containing the channel proteins, contributing not only to the specificity of Kv3 channel transport, but also to the cargo-mediated regulation of motor function.
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Affiliation(s)
- Joshua Barry
- Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, OH 43210, USA
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Ahmad Waza A, Andrabi K, Ul Hussain M. Adenosine-triphosphate-sensitive K+ channel (Kir6.1): a novel phosphospecific interaction partner of connexin 43 (Cx43). Exp Cell Res 2012; 318:2559-66. [PMID: 22960107 DOI: 10.1016/j.yexcr.2012.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 01/30/2023]
Abstract
Connexin 43 (Cx43) is a phosphoprotein expressed in a wide variety of cells. Cx43 and adenosine-triphosphate-sensitive K(+)channels [K(+)(ATP)] are part of same signaling pathway that regulates cell survival during stress and ischemia preconditioning. Molecular mechanism for their coordinated role in ischemia/hypoxia preconditioning is not well known. Using pull down, co-immunoprecipitation assays and co-localization studies we provide evidence, for the first time that Kir6.1, a K(+)(ATP) channel protein component, can interact with Cx43. Further we show that the interaction was phospho-specific such that Cx43 phosphorylated at serine 262 (S262) interacted with Kir6.1 in preference to the unphosphorylated form of Cx43. Introduction of phospho-deficient mutation at serine 262 (S262A) in Cx43 completely abolished the interaction. Our data provide an interesting lead about a possible partnership between Cx43 and Kir6.1, which will help in better understanding their role in ischemia/hypoxia preconditioning.
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Kaufmann WA, Matsui K, Jeromin A, Nerbonne JM, Ferraguti F. Kv4.2 potassium channels segregate to extrasynaptic domains and influence intrasynaptic NMDA receptor NR2B subunit expression. Brain Struct Funct 2012; 218:1115-32. [PMID: 22932868 PMCID: PMC3748322 DOI: 10.1007/s00429-012-0450-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/08/2012] [Indexed: 12/23/2022]
Abstract
Neurons of the intercalated cell clusters (ITCs) represent an important relay site for information flow within amygdala nuclei. These neurons receive mainly glutamatergic inputs from the basolateral amygdala at their dendritic domains and provide feed-forward inhibition to the central nucleus. Voltage-gated potassium channels type-4.2 (Kv4.2) are main players in dendritic signal processing and integration providing a key component of the A currents. In this study, the subcellular localization and distribution of the Kv4.2 was studied in ITC neurons by means of light- and electron microscopy, and compared to other types of central principal neurons. Several ultrastructural immunolocalization techniques were applied including pre-embedding techniques and, most importantly, SDS-digested freeze-fracture replica labeling. We found Kv4.2 densely expressed in somato-dendritic domains of ITC neurons where they show a differential distribution pattern as revealed by nearest neighbor analysis. Comparing ITC neurons with hippocampal pyramidal and cerebellar granule cells, a cell type- and domain-dependent organization in Kv4.2 distribution was observed. Kv4.2 subunits were localized to extrasynaptic sites where they were found to influence intrasynaptic NMDA receptor subunit expression. In samples of Kv4.2 knockout mice, the frequency of NR1-positive synapses containing the NR2B subunit was significantly increased. This indicates a strong, yet indirect effect of Kv4.2 on the synaptic content of NMDA receptor subtypes, and a likely role in synaptic plasticity at ITC neurons.
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Affiliation(s)
- Walter A Kaufmann
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr Strasse 1a, 6020 Innsbruck, Austria.
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