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Zhang M, Zhang Z, Li H, Xia Y, Xing M, Xiao C, Cai W, Bu L, Li Y, Park TE, Tang Y, Ye X, Lin WJ. Blockage of VEGF function by bevacizumab alleviates early-stage cerebrovascular dysfunction and improves cognitive function in a mouse model of Alzheimer's disease. Transl Neurodegener 2024; 13:1. [PMID: 38173017 PMCID: PMC10763201 DOI: 10.1186/s40035-023-00388-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/14/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is a neurodegenerative disorder and the predominant type of dementia worldwide. It is characterized by the progressive and irreversible decline of cognitive functions. In addition to the pathological beta-amyloid (Aβ) deposition, glial activation, and neuronal injury in the postmortem brains of AD patients, increasing evidence suggests that the often overlooked vascular dysfunction is an important early event in AD pathophysiology. Vascular endothelial growth factor (VEGF) plays a critical role in regulating physiological functions and pathological changes in blood vessels, but whether VEGF is involved in the early stage of vascular pathology in AD remains unclear. METHODS We used an antiangiogenic agent for clinical cancer treatment, the humanized monoclonal anti-VEGF antibody bevacizumab, to block VEGF binding to its receptors in the 5×FAD mouse model at an early age. After treatment, memory performance was evaluated by a novel object recognition test, and cerebral vascular permeability and perfusion were examined by an Evans blue assay and blood flow scanning imaging analysis. Immunofluorescence staining was used to measure glial activation and Aβ deposits. VEGF and its receptors were analyzed by enzyme-linked immunosorbent assay and immunoblotting. RNA sequencing was performed to elucidate bevacizumab-associated transcriptional signatures in the hippocampus of 5×FAD mice. RESULTS Bevacizumab treatment administered from 4 months of age dramatically improved cerebrovascular functions, reduced glial activation, and restored long-term memory in both sexes of 5×FAD mice. Notably, a sex-specific change in different VEGF receptors was identified in the cortex and hippocampus of 5×FAD mice. Soluble VEGFR1 was decreased in female mice, while full-length VEGFR2 was increased in male mice. Bevacizumab treatment reversed the altered expression of receptors to be comparable to the level in the wild-type mice. Gene Set Enrichment Analysis of transcriptomic changes revealed that bevacizumab effectively reversed the changes in the gene sets associated with blood-brain barrier integrity and vascular smooth muscle contraction in 5×FAD mice. CONCLUSIONS Our study demonstrated the mechanistic roles of VEGF at the early stage of amyloidopathy and the protective effects of bevacizumab on cerebrovascular function and memory performance in 5×FAD mice. These findings also suggest the therapeutic potential of bevacizumab for the early intervention of AD.
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Affiliation(s)
- Min Zhang
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Province Translational Forensic Medicine Engineering Technology Research Center, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
| | - Zhan Zhang
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China
| | - Honghong Li
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
| | - Yuting Xia
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China
| | - Mengdan Xing
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China
| | - Chuan Xiao
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China
| | - Wenbao Cai
- Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Province Translational Forensic Medicine Engineering Technology Research Center, Sun Yat-sen University, Guangzhou, 510120, China
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China
| | - Lulu Bu
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
| | - Yi Li
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China
| | - Tae-Eun Park
- Department of Biomedical Engineering, College of Information and Biotechnology, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Yamei Tang
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China.
- Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China.
| | - Xiaojing Ye
- Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Province Translational Forensic Medicine Engineering Technology Research Center, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China.
| | - Wei-Jye Lin
- Brain Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510120, China.
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China.
- Nanhai Translational Innovation Center of Precision Immunology, Sun Yat-sen Memorial Hospital, Foshan, 528200, China.
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2
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Kodirov SA. Adam, amigo, brain, and K channel. Biophys Rev 2023; 15:1393-1424. [PMID: 37975011 PMCID: PMC10643815 DOI: 10.1007/s12551-023-01163-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/28/2023] [Indexed: 11/19/2023] Open
Abstract
Voltage-dependent K+ (Kv) channels are diverse, comprising the classical Shab - Kv2, Shaker - Kv1, Shal - Kv4, and Shaw - Kv3 families. The Shaker family alone consists of Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv1.5, Kv1.6, and Kv1.7. Moreover, the Shab family comprises two functional (Kv2.1 and Kv2.2) and several "silent" alpha subunits (Kv2.3, Kv5, Kv6, Kv8, and Kv9), which do not generate K current. However, e.g., Kv8.1, via heteromerization, inhibits outward currents of the same family or even that of Shaw. This property of Kv8.1 is similar to those of designated beta subunits or non-selective auxiliary elements, including ADAM or AMIGO proteins. Kv channels and, in turn, ADAM may modulate the synaptic long-term potentiation (LTP). Prevailingly, Kv1.1 and Kv1.5 are attributed to respective brain and heart pathologies, some of which may occur simultaneously. The aforementioned channel proteins are apparently involved in several brain pathologies, including schizophrenia and seizures.
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Affiliation(s)
- Sodikdjon A. Kodirov
- Department of Biological Sciences, University of Texas at Brownsville, Brownsville, TX 78520 USA
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia
- Instituto de Medicina Molecular, Universidade de Lisboa, 1649-028 Lisbon, Portugal
- Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341 Russia
- Institute for Physiology and Pathophysiology, Johannes Kepler University, Linz, Austria
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3
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Sanders AL, Hermanson JN, Samuels DC, Plate L, Sanders CR. Compendium of proteins containing segments that exhibit
zero‐tolerance
to amino acid variation in humans. Protein Sci 2022; 31:e4408. [PMID: 36040257 PMCID: PMC9387208 DOI: 10.1002/pro.4408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/11/2022] [Accepted: 07/08/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Adam L. Sanders
- Department of Biochemistry Vanderbilt University School of Medicine—Basic Sciences Nashville Tennessee USA
| | - Jake N. Hermanson
- Quantitative Chemical and Physical Biology Graduate Program Vanderbilt University School of Medicine—Basic Sciences Nashville Tennessee USA
| | - David C. Samuels
- Department of Molecular Physiology and Biophysics Vanderbilt University School of Medicine Nashville Tennessee USA
| | - Lars Plate
- Departments of Chemistry and Biological Sciences Vanderbilt University Nashville Tennessee USA
| | - Charles R. Sanders
- Department of Biochemistry Vanderbilt University School of Medicine—Basic Sciences Nashville Tennessee USA
- Center for Structural Biology Vanderbilt University School of Medicine—Basic Sciences Nashville Tennessee USA
- Department of Medicine Vanderbilt University School of Medicine Nashville Tennessee USA
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4
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Jin L, Li Z, Wang C, Wang Y, Li X, Yang J, Zhao Y, Guo B. Contrasting population differentiation in two sympatric Triplophysa loaches on the Qinghai–Tibet Plateau. Front Genet 2022; 13:958076. [PMID: 36092882 PMCID: PMC9452750 DOI: 10.3389/fgene.2022.958076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/15/2022] [Indexed: 11/25/2022] Open
Abstract
Genetic differentiation in aquatic organisms is usually shaped by drainage connectivity. Sympatric aquatic species are thus expected to show similar population differentiation patterns and similar genetic responses to their habitats. Water bodies on the Qinghai–Tibet Plateau (QTP) have recently experienced dramatic physicochemical changes, threatening the biodiversity of aquatic organisms on the “roof of the world.” To uncover ecological genetics in Tibetan loaches (Triplophysa)—the largest component of the QTP ichthyofauna—we characterized population differentiation patterns and adaptive mechanisms to salinity change in two sympatric and phylogenetically closely related Tibetan loaches, T. stewarti and T. stenura, by integrating population genomic, transcriptomic, and electron probe microanalysis approaches. Based on millions of genome-wide SNPs, the two Tibetan loach species show contrasting population differentiation patterns, with highly geographically structured and clear genetic differentiation among T. stewarti populations, whereas there is no such observation in T. stenura, which is also supported by otolith microchemistry mapping. While limited genetic signals of parallel adaption to salinity changes between the two species are found from either genetic or gene expression variation perspective, a catalog of genes involved in ion transport, energy metabolism, structural reorganization, immune response, detoxification, and signal transduction is identified to be related to adaptation to salinity change in Triplophysa loaches. Together, our findings broaden our understanding of the population characteristics and adaptive mechanisms in sympatric Tibetan loach species and would contribute to biodiversity conservation and management of aquatic organisms on the QTP.
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Affiliation(s)
- Ling Jin
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zitong Li
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | - Chongnv Wang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Yingnan Wang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xinxin Li
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Jian Yang
- Assessment and Resource Conservation in Middle and Lower Reaches of the Yangtze River, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Yahui Zhao
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Baocheng Guo
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
- Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, China
- *Correspondence: Baocheng Guo,
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5
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Munjal NS, Sapra D, Parthasarathi KTS, Goyal A, Pandey A, Banerjee M, Sharma J. Deciphering the Interactions of SARS-CoV-2 Proteins with Human Ion Channels Using Machine-Learning-Based Methods. Pathogens 2022; 11:pathogens11020259. [PMID: 35215201 PMCID: PMC8874499 DOI: 10.3390/pathogens11020259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/31/2022] [Accepted: 02/08/2022] [Indexed: 01/04/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is accountable for the protracted COVID-19 pandemic. Its high transmission rate and pathogenicity led to health emergencies and economic crisis. Recent studies pertaining to the understanding of the molecular pathogenesis of SARS-CoV-2 infection exhibited the indispensable role of ion channels in viral infection inside the host. Moreover, machine learning (ML)-based algorithms are providing a higher accuracy for host-SARS-CoV-2 protein–protein interactions (PPIs). In this study, PPIs of SARS-CoV-2 proteins with human ion channels (HICs) were trained on the PPI-MetaGO algorithm. PPI networks (PPINs) and a signaling pathway map of HICs with SARS-CoV-2 proteins were generated. Additionally, various U.S. food and drug administration (FDA)-approved drugs interacting with the potential HICs were identified. The PPIs were predicted with 82.71% accuracy, 84.09% precision, 84.09% sensitivity, 0.89 AUC-ROC, 65.17% Matthews correlation coefficient score (MCC) and 84.09% F1 score. Several host pathways were found to be altered, including calcium signaling and taste transduction pathway. Potential HICs could serve as an initial set to the experimentalists for further validation. The study also reinforces the drug repurposing approach for the development of host directed antiviral drugs that may provide a better therapeutic management strategy for infection caused by SARS-CoV-2.
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Affiliation(s)
- Nupur S. Munjal
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Dikscha Sapra
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - K. T. Shreya Parthasarathi
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Abhishek Goyal
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Akhilesh Pandey
- Center for Molecular Medicine, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore 560029, India;
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Manidipa Banerjee
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India;
| | - Jyoti Sharma
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
- Manipal Academy of Higher Education (MAHE), Udupi 576104, India
- Correspondence:
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6
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KCNG1-Related Syndromic Form of Congenital Neuromuscular Channelopathy in a Crossbred Calf. Genes (Basel) 2021; 12:genes12111792. [PMID: 34828398 PMCID: PMC8618021 DOI: 10.3390/genes12111792] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 10/29/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Inherited channelopathies are a clinically and heritably heterogeneous group of disorders that result from ion channel dysfunction. The aim of this study was to characterize the clinicopathologic features of a Belgian Blue x Holstein crossbred calf with paradoxical myotonia congenita, craniofacial dysmorphism, and myelodysplasia, and to identify the most likely genetic etiology. The calf displayed episodes of exercise-induced generalized myotonic muscle stiffness accompanied by increase in serum potassium. It also showed slight flattening of the splanchnocranium with deviation to the right side. On gross pathology, myelodysplasia (hydrosyringomielia and segmental hypoplasia) in the lumbosacral intumescence region was noticed. Histopathology of the muscle profile revealed loss of the main shape in 5.3% of muscle fibers. Whole-genome sequencing revealed a heterozygous missense variant in KCNG1 affecting an evolutionary conserved residue (p.Trp416Cys). The mutation was predicted to be deleterious and to alter the pore helix of the ion transport domain of the transmembrane protein. The identified variant was present only in the affected calf and not seen in more than 5200 other sequenced bovine genomes. We speculate that the mutation occurred either as a parental germline mutation or post-zygotically in the developing embryo. This study implicates an important role for KCNG1 as a member of the potassium voltage-gated channel group in neurodegeneration. Providing the first possible KCNG1-related disease model, we have, therefore, identified a new potential candidate for related conditions both in animals and in humans. This study illustrates the enormous potential of phenotypically well-studied spontaneous mutants in domestic animals to provide new insights into the function of individual genes.
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7
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Bar C, Kuchenbuch M, Barcia G, Schneider A, Jennesson M, Le Guyader G, Lesca G, Mignot C, Montomoli M, Parrini E, Isnard H, Rolland A, Keren B, Afenjar A, Dorison N, Sadleir LG, Breuillard D, Levy R, Rio M, Dupont S, Negrin S, Danieli A, Scalais E, De Saint Martin A, El Chehadeh S, Chelly J, Poisson A, Lebre A, Nica A, Odent S, Sekhara T, Brankovic V, Goldenberg A, Vrielynck P, Lederer D, Maurey H, Terrone G, Besmond C, Hubert L, Berquin P, Billette de Villemeur T, Isidor B, Freeman JL, Mefford HC, Myers CT, Howell KB, Rodríguez‐Sacristán Cascajo A, Meyer P, Genevieve D, Guët A, Doummar D, Durigneux J, van Dooren MF, de Wit MCY, Gerard M, Marey I, Munnich A, Guerrini R, Scheffer IE, Kabashi E, Nabbout R. Developmental and epilepsy spectrum of
KCNB1
encephalopathy with long‐term outcome. Epilepsia 2020; 61:2461-2473. [DOI: 10.1111/epi.16679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Claire Bar
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Mathieu Kuchenbuch
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Giulia Barcia
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
| | - Amy Schneider
- Department of Medicine Epilepsy Research Centre Austin Health University of Melbourne Heidelberg Victoria Australia
| | | | - Gwenaël Le Guyader
- Department of Genetics Poitiers University Hospital CenterPoitiers Cedex France
- EA3808–NEUVACOD Neurovascular and Cognitive Disorders Unit University of Poitiers Poitiers France
| | - Gaetan Lesca
- Department of Genetics Lyon Civil Hospices Lyon France
- NeuroMyoGène Institute National Center for Scientific Research Mixed Unit of Research 5310, National Institute of Health and Medical Research U1217University of LyonClaude Bernard Lyon 1 University Villeurbanne France
| | - Cyril Mignot
- National Institute of Health and Medical Research, U1127 National Center for Scientific Research Mixed Unit of Research 7225 Pierre and Marie Curie University Paris 6 Mixed Unit of Research S1127 Brain and Spine Institute Sorbonne University Paris France
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Martino Montomoli
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Hervé Isnard
- Pediatric Neurologist Medical Office Lyon France
| | - Anne Rolland
- Department of Pediatrics Nantes University Hospital Center Nantes France
| | - Boris Keren
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Alexandra Afenjar
- Department of Genetics and Medical Embryology Reference Center for Malformations and Congenital Diseases of the Cerebellum and Rare Causes of Intellectual Disabilities Sorbonne UniversityAP‐HP, Trousseau Hospital Paris France
| | - Nathalie Dorison
- Pediatric Neurosurgery Department Rothschild Foundation Hospital Paris France
- Department of Pediatric Neurology AP‐HP, Armand Trousseau HospitalSorbonne University Paris France
| | - Lynette G. Sadleir
- Department of Pediatrics and Child Health University of Otago Wellington New Zealand
| | - Delphine Breuillard
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Raphael Levy
- Department of Pediatric Radiology Necker‐Enfants Malades Hospital Paris France
| | - Marlène Rio
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
- Laboratory of Developmental Brain Disorders National Institute of Health and Medical Research Mixed Unit of Research 1163 Imagine InstituteSorbonne University Paris France
| | - Sophie Dupont
- National Institute of Health and Medical Research, U1127 National Center for Scientific Research Mixed Unit of Research 7225 Pierre and Marie Curie University Paris 6 Mixed Unit of Research S1127 Brain and Spine Institute Sorbonne University Paris France
- Epileptology Unit and Rehabilitation Unit AP‐HP, Pitie‐Salpêtrière‐Charles Foix Hospital Paris France
| | - Susanna Negrin
- Epilepsy and Clinical Neurophysiology Unit Scientific InstituteIRCCS E. Medea Treviso Italy
| | - Alberto Danieli
- Epilepsy and Clinical Neurophysiology Unit Scientific InstituteIRCCS E. Medea Treviso Italy
| | - Emmanuel Scalais
- Pediatric Neurology Unit Luxembourg Hospital Center Luxembourg City Luxembourg
| | - Anne De Saint Martin
- Department of Pediatric Neurology Strasbourg University HospitalHautepierre Hospital Strasbourg France
| | - Salima El Chehadeh
- Department of Medical Genetics Strasbourg University HospitalsHautepierre Hospital Strasbourg France
| | - Jamel Chelly
- Department of Medical Genetics Strasbourg University HospitalsHautepierre Hospital Strasbourg France
| | - Alice Poisson
- GénoPsy Reference Center for Diagnosis and Management of Genetic Psychiatric Disorders le Vinatier Hospital Center and EDR‐Psy Team (National Center for Scientific Research and Lyon 1 Claude Bernard University) Villeurbanne France
| | - Anne‐Sophie Lebre
- Reims University Hospital CenterMaison Blanche HospitalBiology Department Reims France
| | - Anca Nica
- Neurology Department Center for Clinical Research (CIC 1414) Rennes University Hospital Rennes France
- Laboratory of Signal ProcessingNational Institute of Health and Medical Research Mixed Unit of Research 1099 Rennes France
| | - Sylvie Odent
- Reference Center for Rare Developmental Abnormalities CLAD‐Ouest Rennes University Hospital Center Rennes France
- National Center for Scientific Research Mixed Unit of Research 6290, Institute of Genetics and Development of Rennes (IGDR)University of Rennes Rennes France
| | - Tayeb Sekhara
- Department of Pediatric Neurology C.H.I.R.E.C Brussels Belgium
| | | | - Alice Goldenberg
- Reference Center for Developmental Anomalies and Malformation Syndromes Rouen University Hospital Center Rouen France
| | - Pascal Vrielynck
- Reference Center for Refractory Epilepsy, Catholic University of Louvain William Lennox Neurological Hospital Ottignies Belgium
| | | | - Hélène Maurey
- Department of Pediatric Neurology AP‐HP, Bicêtre University Hospital Kremlin Bicêtre France
| | - Gaetano Terrone
- Department of Translational Medical Sciences Section of Pediatrics, Child Neurology Unit Federico II University Naples Italy
| | - Claude Besmond
- Translational Genetics National Institute of Health and Medical Research Mixed Unit of Research 1163Imagine InstituteUniversity of Paris Paris France
| | - Laurence Hubert
- Translational Genetics National Institute of Health and Medical Research Mixed Unit of Research 1163Imagine InstituteUniversity of Paris Paris France
| | - Patrick Berquin
- Department of Pediatric Neurology Amiens‐Picardie University Hospital CenterUniversity of Picardy Jules Verne Amiens France
| | | | - Bertrand Isidor
- Department of Clinical Genetics Nantes University Hospital Center Nantes France
| | - Jeremy L. Freeman
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
| | - Heather C. Mefford
- Department of Pediatrics Division of Genetic Medicine University of Washington Seattle Washington United States
| | - Candace T. Myers
- Department of Pediatrics Division of Genetic Medicine University of Washington Seattle Washington United States
| | - Katherine B. Howell
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
| | - Andrés Rodríguez‐Sacristán Cascajo
- Pediatric Neurology Unit Department of Pediatric Virgen Macarena Hospital Seville Spain
- Department of Pediatrics School of Medicine University of Seville Seville Spain
| | - Pierre Meyer
- Department of Pediatric Neurology Montpellier University Hospital Center Montpellier France
- PhyMedExp National Institute of Health and Medical Research, U1046National Center for Scientific Research Mixed Unit of Research 9214University of Montpellier Montpellier France
| | - David Genevieve
- Department of Medical Genetics, Rare Disease, and Personalized Medicine IRMBUniversity of MontpellierNational Institute of Health and Medical ResearchMontpellier University Hospital Center Montpellier France
| | - Agnès Guët
- Department of Pediatrics Louis‐Mourier Hospital Colombes France
| | - Diane Doummar
- Department of Pediatric Neurology AP‐HP, Armand Trousseau HospitalSorbonne University Paris France
| | - Julien Durigneux
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
| | - Marieke F. van Dooren
- Department of Clinical Genetics Erasmus University Medical Center Rotterdam the Netherlands
| | - Marie Claire Y. de Wit
- Department of Pediatric Neurology and ENCORE Expertise Center Erasmus University Medical Center Sophia Children’s Hospital Rotterdam the Netherlands
| | - Marion Gerard
- Clinical Genetics Côte de Nacre University Hospital Center Caen France
| | - Isabelle Marey
- Department of Genetics Rare Causes of Intellectual Disability Reference Center AP‐HP, Pitié‐Salpêtrière HospitalSorbonne University Paris France
| | - Arnold Munnich
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
- Department of Clinical Genetics AP‐HP, Necker‐Enfants Malades Hospital Paris France
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics, and Neurobiology Unit and Laboratories Neuroscience Department A. Meyer Children's HospitalUniversity of Florence Florence Italy
| | - Ingrid E. Scheffer
- Department of Medicine Epilepsy Research Centre Austin Health University of Melbourne Heidelberg Victoria Australia
- Departments of Neurology and Paediatrics Royal Children's Hospital University of Melbourne Melbourne Victoria Australia
- Murdoch Children’s Research Institute Melbourne Victoria Australia
- Florey Institute of Neurosciences and Mental Health Heidelberg Victoria Australia
| | - Edor Kabashi
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
| | - Rima Nabbout
- Department of Pediatric Neurology Reference Center for Rare Epilepsies Assistance Publique‐Hôpitaux de Paris (AP‐HP), Necker‐Enfants Malades Hospital Paris France
- Imagine Institute, Mixed Unit of Research 1163 University of ParisSorbonne University Paris France
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8
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Determining the correct stoichiometry of Kv2.1/Kv6.4 heterotetramers, functional in multiple stoichiometrical configurations. Proc Natl Acad Sci U S A 2020; 117:9365-9376. [PMID: 32284408 DOI: 10.1073/pnas.1916166117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The electrically silent (KvS) members of the voltage-gated potassium (Kv) subfamilies Kv5, Kv6, Kv8, and Kv9 selectively modulate Kv2 subunits by forming heterotetrameric Kv2/KvS channels. Based on the reported 3:1 stoichiometry of Kv2.1/Kv9.3 channels, we tested the hypothesis that Kv2.1/Kv6.4 channels express, in contrast to the assumed 3:1, in a 2:2 stoichiometry. We investigate the Kv2.1/Kv6.4 stoichiometry using single subunit counting and functional characterization of tetrameric concatemers. For selecting the most probable stoichiometry, we introduce a model-selection method that is applicable for any multimeric complex by investigating the stoichiometry of Kv2.1/Kv6.4 channels. Weighted likelihood calculations bring rigor to a powerful technique. Using the weighted-likelihood model-selection method and analysis of electrophysiological data, we show that Kv2.1/Kv6.4 channels express, in contrast to the assumed 3:1, in a 2:2 stoichiometry. Within this stoichiometry, the Kv6.4 subunits have to be positioned alternating with Kv2.1 to express functional channels. The variability in Kv2/KvS assembly increases the diversity of heterotetrameric configurations and extends the regulatory possibilities of KvS by allowing the presence of more than one silent subunit.
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9
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Bocksteins E. Kv5, Kv6, Kv8, and Kv9 subunits: No simple silent bystanders. J Gen Physiol 2016; 147:105-25. [PMID: 26755771 PMCID: PMC4727947 DOI: 10.1085/jgp.201511507] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/11/2015] [Indexed: 12/19/2022] Open
Abstract
Members of the electrically silent voltage-gated K(+) (Kv) subfamilies (Kv5, Kv6, Kv8, and Kv9, collectively identified as electrically silent voltage-gated K(+) channel [KvS] subunits) do not form functional homotetrameric channels but assemble with Kv2 subunits into heterotetrameric Kv2/KvS channels with unique biophysical properties. Unlike the ubiquitously expressed Kv2 subunits, KvS subunits show a more restricted expression. This raises the possibility that Kv2/KvS heterotetramers have tissue-specific functions, making them potential targets for the development of novel therapeutic strategies. Here, I provide an overview of the expression of KvS subunits in different tissues and discuss their proposed role in various physiological and pathophysiological processes. This overview demonstrates the importance of KvS subunits and Kv2/KvS heterotetramers in vivo and the importance of considering KvS subunits and Kv2/KvS heterotetramers in the development of novel treatments.
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Affiliation(s)
- Elke Bocksteins
- Laboratory for Molecular Biophysics, Physiology, and Pharmacology, Department for Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium
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10
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Bocksteins E, Mayeur E, Van Tilborg A, Regnier G, Timmermans JP, Snyders DJ. The subfamily-specific interaction between Kv2.1 and Kv6.4 subunits is determined by interactions between the N- and C-termini. PLoS One 2014; 9:e98960. [PMID: 24901643 PMCID: PMC4047056 DOI: 10.1371/journal.pone.0098960] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 05/08/2014] [Indexed: 12/14/2022] Open
Abstract
The "silent" voltage-gated potassium (KvS) channel subunit Kv6.4 does not form electrically functional homotetramers at the plasma membrane but assembles with Kv2.1 subunits, generating functional Kv2.1/Kv6.4 heterotetramers. The N-terminal T1 domain determines the subfamily-specific assembly of Kv1-4 subunits by preventing interactions between subunits that belong to different subfamilies. For Kv6.4, yeast-two-hybrid experiments showed an interaction of the Kv6.4 N-terminus with the Kv2.1 N-terminus, but unexpectedly also with the Kv3.1 N-terminus. We confirmed this interaction by Fluorescence Resonance Energy Transfer (FRET) and co-immunoprecipitation (co-IP) using N-terminal Kv3.1 and Kv6.4 fragments. However, full-length Kv3.1 and Kv6.4 subunits do not form heterotetramers at the plasma membrane. Therefore, additional interactions between the Kv6.4 and Kv2.1 subunits should be important in the Kv2.1/Kv6.4 subfamily-specificity. Using FRET and co-IP approaches with N- and C-terminal fragments we observed that the Kv6.4 C-terminus physically interacts with the Kv2.1 N-terminus but not with the Kv3.1 N-terminus. The N-terminal amino acid sequence CDD which is conserved between Kv2 and KvS subunits appeared to be a key determinant since charge reversals with arginine substitutions abolished the interaction between the N-terminus of Kv2.1 and the C-terminus of both Kv2.1 and Kv6.4. In addition, the Kv6.4(CKv3.1) chimera in which the C-terminus of Kv6.4 was replaced by the corresponding domain of Kv3.1, disrupted the assembly with Kv2.1. These results indicate that the subfamily-specific Kv2.1/Kv6.4 heterotetramerization is determined by interactions between Kv2.1 and Kv6.4 that involve both the N- and C-termini in which the conserved N-terminal CDD sequence plays a key role.
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Affiliation(s)
- Elke Bocksteins
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Evy Mayeur
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Abbi Van Tilborg
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Glenn Regnier
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Jean-Pierre Timmermans
- Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
| | - Dirk J. Snyders
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- * E-mail:
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11
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Smith KE, Wilkie SE, Tebbs-Warner JT, Jarvis BJ, Gallasch L, Stocker M, Hunt DM. Functional analysis of missense mutations in Kv8.2 causing cone dystrophy with supernormal rod electroretinogram. J Biol Chem 2012; 287:43972-83. [PMID: 23115240 DOI: 10.1074/jbc.m112.388033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in KCNV2 have been proposed as the molecular basis for cone dystrophy with supernormal rod electroretinogram. KCNV2 codes for the modulatory voltage-gated potassium channel α-subunit, Kv8.2, which is incapable of forming functional channels on its own. Functional heteromeric channels are however formed with Kv2.1 in heterologous expression systems, with both α-subunit genes expressed in rod and cone photoreceptors. Of the 30 mutations identified in the KCNV2 gene, we have selected three missense mutations localized in the potassium channel pore and two missense mutations localized in the tetramerization domain for analysis. We characterized the differences between homomeric Kv2.1 and heteromeric Kv2.1/Kv8.2 channels and investigated the influence of the selected mutations on the function of heteromeric channels. We found that two pore mutations (W467G and G478R) led to the formation of nonconducting heteromeric Kv2.1/Kv8.2 channels, whereas the mutations localized in the tetramerization domain prevented heteromer generation and resulted in the formation of homomeric Kv2.1 channels only. Consequently, our study suggests the existence of two distinct molecular mechanisms involved in the disease pathology.
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Affiliation(s)
- Katie E Smith
- University College London Institute of Ophthalmology, London EC1V 9EL, United Kingdom
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12
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Bocksteins E, Snyders DJ. Electrically Silent Kv Subunits: Their Molecular and Functional Characteristics. Physiology (Bethesda) 2012; 27:73-84. [DOI: 10.1152/physiol.00023.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Electrically silent voltage-gated potassium (KvS) α-subunits do not form homotetramers but heterotetramerize with Kv2 subunits, generating functional Kv2/KvS channel complexes in which the KvS subunits modulate the Kv2 current. This poses intriguing questions into the molecular mechanisms by which these KvS subunits cannot form functional homotetramers, why they only interact with Kv2 subunits, and how they modulate the Kv2 current.
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Affiliation(s)
- Elke Bocksteins
- Department of Biomedical Sciences, Laboratory for Molecular Biophysics, Physiology and Pharmacology, University of Antwerp, Antwerpen, Belgium
| | - Dirk J. Snyders
- Department of Biomedical Sciences, Laboratory for Molecular Biophysics, Physiology and Pharmacology, University of Antwerp, Antwerpen, Belgium
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13
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Subunit-dependent axonal trafficking of distinct alpha heteromeric potassium channel complexes. J Neurosci 2011; 31:13224-35. [PMID: 21917805 DOI: 10.1523/jneurosci.0976-11.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated potassium (Kv) channels are critical for neuronal excitability and are targeted to specific subcellular compartments to carry out their unique functions. While it is widely believed that Kv channels exist as heteromeric complexes in neurons, direct tests of the hypothesis that specific heteromeric channel populations display divergent spatial and temporal dynamics are limited. Using a bimolecular fluorescence complementation approach, we monitored the assembly and localization of cell surface channel complexes in living cells. While PSD95-mediated clustering was subunit independent, selective visualization of heteromeric Kv complexes in rat hippocampal neurons revealed subunit-dependent localization that was not predicted by analyzing individual subunits. Assembly of Kv1.1 with Kv1.4 prevented axonal localization but not surface expression, while inclusion of Kv1.2 imparted clustering at presynaptic sites and decreased channel mobility within the axon. This mechanism by which specific Kv channel subunits can act in a dominant manner to impose unique trafficking properties to heteromeric complexes extended to Shab-related family of Kv channels. When coexpressed, Kv2.1 and Kv2.2 heteromultimers did not aggregate in somatodendritic clusters observed with expression of Kv2.1 alone. These studies demonstrate selective axonal trafficking and surface localization of distinct Kv channels based on their subunit composition.
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14
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Kihira Y, Hermanstyne TO, Misonou H. Formation of heteromeric Kv2 channels in mammalian brain neurons. J Biol Chem 2010; 285:15048-15055. [PMID: 20202934 DOI: 10.1074/jbc.m109.074260] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The formation of heteromeric tetramers is a common feature of voltage-gated potassium (Kv) channels. This results in the generation of a variety of tetrameric Kv channels that exhibit distinct biophysical and biochemical characteristics. Kv2 delayed rectifier channels are, however, unique exceptions. It has been previously shown that mammalian Kv2.1 and Kv2.2 are localized in distinct domains of neuronal membranes and are not capable of forming heteromeric channels with each other (Hwang, P. M., Glatt, C. E., Bredt, D. S., Yellen, G., and Snyder, S. H. (1992) Neuron 8, 473-481). In this study, we report a novel form of rat Kv2.2, Kv2.2(long), which has not been previously recognized. Our data indicate that Kv2.2(long) is the predominant form of Kv2.2 expressed in cortical pyramidal neurons. In contrast to the previous findings, we also found that rat Kv2.1 and Kv2.2(long) are colocalized in the somata and proximal dendrites of cortical pyramidal neurons and are capable of forming functional heteromeric delayed rectifier channels. Our results suggest that the delayed rectifier currents, which regulate action potential firing, are encoded by heteromeric Kv2 channels in cortical neurons.
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Affiliation(s)
- Yoshitaka Kihira
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201
| | - Tracey O Hermanstyne
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201; Program in Neuroscience, University of Maryland, Baltimore, Maryland 21201
| | - Hiroaki Misonou
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201; Program in Neuroscience, University of Maryland, Baltimore, Maryland 21201.
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15
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Bocksteins E, Labro AJ, Mayeur E, Bruyns T, Timmermans JP, Adriaensen D, Snyders DJ. Conserved negative charges in the N-terminal tetramerization domain mediate efficient assembly of Kv2.1 and Kv2.1/Kv6.4 channels. J Biol Chem 2009; 284:31625-34. [PMID: 19717558 DOI: 10.1074/jbc.m109.039479] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated potassium (Kv) channels are transmembrane tetramers of individual alpha-subunits. Eight different Shaker-related Kv subfamilies have been identified in which the tetramerization domain T1, located on the intracellular N terminus, facilitates and controls the assembly of both homo- and heterotetrameric channels. Only the Kv2 alpha-subunits are able to form heterotetramers with members of the silent Kv subfamilies (Kv5, Kv6, Kv8, and Kv9). The T1 domain contains two subdomains, A and B box, which presumably determine subfamily specificity by preventing incompatible subunits to assemble. In contrast, little is known about the involvement of the A/B linker sequence. Both Kv2 and silent Kv subfamilies contain a fully conserved and negatively charged sequence (CDD) in this linker that is lacking in the other subfamilies. Neutralizing these aspartates in Kv2.1 by mutating them to alanines did not affect the gating properties, but reduced the current density moderately. However, charge reversal arginine substitutions strongly reduced the current density of these homotetrameric mutant Kv2.1 channels and immunocytochemistry confirmed the reduced expression at the plasma membrane. Förster resonance energy transfer measurements using confocal microscopy showed that the latter was not due to impaired trafficking, but to a failure to assemble the tetramer. This was further confirmed with co-immunoprecipitation experiments. The corresponding arginine substitution in Kv6.4 prevented its heterotetrameric interaction with Kv2.1. These results indicate that these aspartates (especially the first one) in the A/B box linker of the T1 domain are required for efficient assembly of both homotetrameric Kv2.1 and heterotetrameric Kv2.1/silent Kv6.4 channels.
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Affiliation(s)
- Elke Bocksteins
- Department of Biomedical Sciences, Laboratory for Molecular Biophysics, Physiology and Pharmacology, University of Antwerp, CDE, Universiteitsplein 1, 2610 Antwerp, Belgium
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