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Wang S, Zhang N, Xu H, Tan L, Wang J. Allelochemicals of Alexandrium tamarense and its algicidal mechanism for Prorocentrum donghaiense and Heterosigma akashiwo. CHEMOSPHERE 2024; 357:141953. [PMID: 38614395 DOI: 10.1016/j.chemosphere.2024.141953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/19/2024] [Accepted: 04/07/2024] [Indexed: 04/15/2024]
Abstract
The effects of culture filtrate of Alexandrium tamarense on Prorocentrum donghaiense and Heterosigma akashiwo were investigated, including determination of algal density, photosynthesis, intracellular enzyme content and activity. The filtrate of A. tamarense had a stronger inhibitory effect on P. donghaiense than H. akashiwo, and the inhibitory effect decreased with higher temperature treatment of the filtrate. Instantaneous fluorescence (Ft) and maximum quantum yield of photosystem II (Fv/Fm) values of both kinds of target algae were reduced as exposed to the filtrate of A. tamarense, which proved that allelopathy could inhibit the normal operation of photosynthetic system. The increase of Malondialdehyde (MDA) content of the two kinds of target algae indicated that the cell membrane was seriously damaged by allelochemicals released by A. tamarense. The different responses of Superoxide Dismutase (SOD) and Catalase (CAT) activity in two kinds of target algae demonstrated the complexity and diversity of allelopathic mechanism. The filtrate of A. tamarense also influenced the metabolic function (ATPases) of P. donghaiense and H. akashiwo, and the influence on P. donghaiense was greater. Liquid-liquid extraction was used to extract and isolate allelochemicals from the filtrate of A. tamarense. It was found that only component I with molecular weight of 424.2573 and 434.2857 could inhibit the growth of P. donghaiense by HPLC-MS.
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Affiliation(s)
- Shuhui Wang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Na Zhang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Hongyan Xu
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Liju Tan
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China
| | - Jiangtao Wang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
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Gu S, Zhu F, Zhang L, Wen J. Mid-Long Chain Dicarboxylic Acid Production via Systems Metabolic Engineering: Progress and Prospects. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:5555-5573. [PMID: 38442481 DOI: 10.1021/acs.jafc.4c00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Mid-to-long-chain dicarboxylic acids (DCAi, i ≥ 6) are organic compounds in which two carboxylic acid functional groups are present at the terminal position of the carbon chain. These acids find important applications as structural components and intermediates across various industrial sectors, including organic compound synthesis, food production, pharmaceutical development, and agricultural manufacturing. However, conventional petroleum-based DCA production methods cause environmental pollution, making sustainable development challenging. Hence, the demand for eco-friendly processes and renewable raw materials for DCA production is rising. Owing to advances in systems metabolic engineering, new tools from systems biology, synthetic biology, and evolutionary engineering can now be used for the sustainable production of energy-dense biofuels. Here, we explore systems metabolic engineering strategies for DCA synthesis in various chassis via the conversion of different raw materials into mid-to-long-chain DCAs. Subsequently, we discuss the future challenges in this field and propose synthetic biology approaches for the efficient production and successful commercialization of these acids.
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Affiliation(s)
- Shanna Gu
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals Co., Ltd, Dalian 116045, China
| | - Fuzhou Zhu
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
| | - Lin Zhang
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals Co., Ltd, Dalian 116045, China
| | - Jianping Wen
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
- Frontiers Science Center for Synthetic Biology (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072,China
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Calame DG, Moreno Vadillo C, Berger S, Lotze T, Shinawi M, Poupak J, Heller C, Cohen J, Person R, Telegrafi A, Phitsanuwong C, Fiala K, Thiffault I, Del Viso F, Zhou D, Fleming EA, Pastinen T, Fatemi A, Thomas S, Pascual SI, Torres RJ, Prior C, Gómez-González C, Biskup S, Lupski JR, Maric D, Holmgren M, Regier D, Yano ST. Cation leak through the ATP1A3 pump causes spasticity and intellectual disability. Brain 2023; 146:3162-3171. [PMID: 37043503 PMCID: PMC10393399 DOI: 10.1093/brain/awad124] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 02/09/2023] [Accepted: 02/28/2023] [Indexed: 04/13/2023] Open
Abstract
ATP1A3 encodes the α3 subunit of the sodium-potassium ATPase, one of two isoforms responsible for powering electrochemical gradients in neurons. Heterozygous pathogenic ATP1A3 variants produce several distinct neurological syndromes, yet the molecular basis for phenotypic variability is unclear. We report a novel recurrent variant, ATP1A3(NM_152296.5):c.2324C>T; p.(Pro775Leu), in nine individuals associated with the primary clinical features of progressive or non-progressive spasticity and developmental delay/intellectual disability. No patients fulfil diagnostic criteria for ATP1A3-associated syndromes, including alternating hemiplegia of childhood, rapid-onset dystonia-parkinsonism or cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss (CAPOS), and none were suspected of having an ATP1A3-related disorder. Uniquely among known ATP1A3 variants, P775L causes leakage of sodium ions and protons into the cell, associated with impaired sodium binding/occlusion kinetics favouring states with fewer bound ions. These phenotypic and electrophysiologic studies demonstrate that ATP1A3:c.2324C>T; p.(Pro775Leu) results in mild ATP1A3-related phenotypes resembling complex hereditary spastic paraplegia or idiopathic spastic cerebral palsy. Cation leak provides a molecular explanation for this genotype-phenotype correlation, adding another mechanism to further explain phenotypic variability and highlighting the importance of biophysical properties beyond ion transport rate in ion transport diseases.
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Affiliation(s)
- Daniel G Calame
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Texas Children’s Hospital, Houston, TX 77030, USA
| | - Cristina Moreno Vadillo
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Seth Berger
- Children’s National Rare Disease Institute, Children’s National Hospital, Washington, DC 20012, USA
| | - Timothy Lotze
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Texas Children’s Hospital, Houston, TX 77030, USA
| | - Marwan Shinawi
- Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Corina Heller
- Praxis Für Humangenetik Tübingen, Tuebingen 72076, Germany
- CeGaT GmbH, Tuebingen 72076, Germany
| | - Julie Cohen
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | | | | | - Chalongchai Phitsanuwong
- Section of Pediatric Neurology, Department of Pediatrics, Comer Children’s Hospital, University of Chicago, Chicago, IL 60637, USA
| | - Kaylene Fiala
- Section of Pediatric Neurology, Department of Pediatrics, Comer Children’s Hospital, University of Chicago, Chicago, IL 60637, USA
| | - Isabelle Thiffault
- Genomic Medicine Center, Children's Mercy Research Institute, Kansas City, MO 64108, USA
- School of Medicine, University of Missouri Kansas City, Kansas City, MO 64108, USA
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Florencia Del Viso
- Genomic Medicine Center, Children's Mercy Research Institute, Kansas City, MO 64108, USA
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Dihong Zhou
- School of Medicine, University of Missouri Kansas City, Kansas City, MO 64108, USA
- Department of Genetics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Emily A Fleming
- Department of Genetics, Children's Mercy Hospital, Kansas City, MO 64108, USA
| | - Tomi Pastinen
- Genomic Medicine Center, Children's Mercy Research Institute, Kansas City, MO 64108, USA
- School of Medicine, University of Missouri Kansas City, Kansas City, MO 64108, USA
| | - Ali Fatemi
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Sruthi Thomas
- Departments of Physical Medicine & Rehabilitation and Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Samuel I Pascual
- Department of Pediatric Neurology, La Paz University Hospital, Madrid, Spain
| | - Rosa J Torres
- La Paz University Hospital Health Research Institute (FIBHULP), IdiPaz, Madrid, Spain
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 20829 Madrid, Spain
| | - Carmen Prior
- Department of Genetics, Genetic Service, La Paz University Hospital, Madrid, Spain
| | - Clara Gómez-González
- Department of Genetics, Genetic Service, La Paz University Hospital, Madrid, Spain
| | - Saskia Biskup
- Praxis Für Humangenetik Tübingen, Tuebingen 72076, Germany
- CeGaT GmbH, Tuebingen 72076, Germany
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Texas Children’s Hospital, Houston, TX 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Miguel Holmgren
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Debra Regier
- Children’s National Rare Disease Institute, Children’s National Hospital, Washington, DC 20012, USA
| | - Sho T Yano
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Sokolov VS. Investigations of Electrogenic Ion Transport by Na+,K+-ATPase in Bilayer Lipid Membranes by Impedance Method. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2022. [DOI: 10.1134/s1990747822050117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Structure and function of H +/K + pump mutants reveal Na +/K + pump mechanisms. Nat Commun 2022; 13:5270. [PMID: 36085139 PMCID: PMC9463140 DOI: 10.1038/s41467-022-32793-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/17/2022] [Indexed: 11/09/2022] Open
Abstract
Ion-transport mechanisms evolve by changing ion-selectivity, such as switching from Na+ to H+ selectivity in secondary-active transporters or P-type-ATPases. Here we study primary-active transport via P-type ATPases using functional and structural analyses to demonstrate that four simultaneous residue substitutions transform the non-gastric H+/K+ pump, a strict H+-dependent electroneutral P-type ATPase, into a bona fide Na+-dependent electrogenic Na+/K+ pump. Conversion of a H+-dependent primary-active transporter into a Na+-dependent one provides a prototype for similar studies of ion-transport proteins. Moreover, we solve the structures of the wild-type non-gastric H+/K+ pump, a suitable drug target to treat cystic fibrosis, and of its Na+/K+ pump-mimicking mutant in two major conformations, providing insight on how Na+ binding drives a concerted mechanism leading to Na+/K+ pump phosphorylation.
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Sah D, Rai JPN, Ghosh A, Chakraborty M. A review on biosurfactant producing bacteria for remediation of petroleum contaminated soils. 3 Biotech 2022; 12:218. [PMID: 35965658 PMCID: PMC9365905 DOI: 10.1007/s13205-022-03277-1] [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: 05/09/2022] [Accepted: 07/21/2022] [Indexed: 11/01/2022] Open
Abstract
The discharge of potentially toxic petroleum hydrocarbons into the environment has been a matter of concern, as these organic pollutants accumulate in many ecosystems due to their hydrophobicity and low bioavailability. Petroleum hydrocarbons are neurotoxic and carcinogenic organic pollutants, extremely harmful to human and environmental health. Traditional treatment methods for removing hydrocarbons from polluted areas, including various mechanical and chemical strategies, are ineffective and costly. However, many indigenous microorganisms in soil and water can utilise hydrocarbon compounds as sources of carbon and energy and hence, can be employed to degrade hydrocarbon contaminants. Therefore, bioremediation using bacteria that degrade petroleum hydrocarbons is commonly viewed as an environmentally acceptable and effective method. The efficacy of bioremediation can be boosted further by using potential biosurfactant-producing microorganisms, as biosurfactants reduce surface tension, promote emulsification and micelle formation, making hydrocarbons bio-available for microbial breakdown. Further, introducing nanoparticles can improve the solubility of hydrophobic hydrocarbons as well as microbial synthesis of biosurfactants, hence establishing a favourable environment for microbial breakdown of these chemicals. The review provides insights into the role of microbes in the bioremediation of soils contaminated with petroleum hydrocarbons and emphasises the significance of biosurfactants and potential biosurfactant-producing bacteria. The review partly focusses on how nanotechnology is being employed in different critical bioremediation processes.
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Affiliation(s)
- Diksha Sah
- Department of Environmental Sciences, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 India
| | - J. P. N. Rai
- Department of Environmental Sciences, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 India
| | - Ankita Ghosh
- Department of Environmental Sciences, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 India
| | - Moumita Chakraborty
- Department of Environmental Sciences, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 India
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7
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Li Y, Liu X, Wang C, Su Z, Zhao K, Yang M, Chen S, Zhou L. Molecular and clinical characteristics of ATP1A3-related diseases. Front Neurol 2022; 13:924788. [PMID: 35968298 PMCID: PMC9373902 DOI: 10.3389/fneur.2022.924788] [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: 04/20/2022] [Accepted: 06/27/2022] [Indexed: 11/14/2022] Open
Abstract
Objective With detailed studies of ATP1A3-related diseases, the phenotypic spectrum of ATP1A3 has greatly expanded. This study aimed to potentially identify the mechanisms by which ATP1A3 caused neurological dysfunction by analyzing the clinical features and phenotypes of ATP1A3-related diseases, and exploring the distribution patterns of mutations in the subregions of the ATP1A3 protein, thus providing new and effective therapeutic approaches. Methods Databases of PubMed, Online Mendelian Inheritance in Man, and Human Gene Mutation Database, Wanfang Data, and Embase were searched for case reports of ATP1A3-related diseases. Following case screening, we collected clinical information and genetic testing results of patients, and analyzed the disease characteristics on the clinical phenotype spectrum associated with mutations, genetic characteristics of mutations, and effects of drug therapy. Results We collected 902 clinical cases related to ATP1A3 gene. From the results of previous studies, we further clarified the clinical characteristics of ATP1A3-related diseases, such as alternating hemiplegia of childhood (AHC), rapid-onset dystonia-parkinsonism; cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss syndrome, and relapsing encephalopathy with cerebellar ataxia, frequency of mutations in different phenotypes and their distribution in gene and protein structures, and differences in mutations in different clinical phenotypes. Regarding the efficacy of drug treatment, 80 of the 124 patients with AHC were treated with flunarizine, with an effectiveness rate of ~64.5%. Conclusions Nervous system dysfunction due to mutations of ATP1A3 gene was characterized by a group of genotypic–phenotypic interrelated disease pedigrees with multiple clinical manifestations. The presented results might help guide the diagnosis and treatment of ATP1A3-related diseases and provided new ideas for further exploring the mechanisms of nervous system diseases due to ATP1A3 mutations.
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Affiliation(s)
- Yinchao Li
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Xianyue Liu
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Chengzhe Wang
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zhengwei Su
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Ke Zhao
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Man Yang
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Shuda Chen
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
- *Correspondence: Shuda Chen
| | - Liemin Zhou
- Department of Neurology, The Seven Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Liemin Zhou
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8
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Fedosova NU, Habeck M, Nissen P. Structure and Function of Na,K-ATPase-The Sodium-Potassium Pump. Compr Physiol 2021; 12:2659-2679. [PMID: 34964112 DOI: 10.1002/cphy.c200018] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Na,K-ATPase is an ubiquitous enzyme actively transporting Na-ions out of the cell in exchange for K-ions, thereby maintaining their concentration gradients across the cell membrane. Since its discovery more than six decades ago the Na-pump has been studied extensively and its vital physiological role in essentially every cell has been established. This article aims at providing an overview of well-established biochemical properties with a focus on Na,K-ATPase isoforms, its transport mechanism and principle conformations, inhibitors, and insights gained from crystal structures. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.
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Affiliation(s)
| | - Michael Habeck
- Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
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Juhaszova M, Kobrinsky E, Zorov DB, Nuss HB, Yaniv Y, Fishbein KW, de Cabo R, Montoliu L, Gabelli SB, Aon MA, Cortassa S, Sollott SJ. ATP Synthase K +- and H +-Fluxes Drive ATP Synthesis and Enable Mitochondrial K +-"Uniporter" Function: I. Characterization of Ion Fluxes. FUNCTION (OXFORD, ENGLAND) 2021; 3:zqab065. [PMID: 35229078 PMCID: PMC8867323 DOI: 10.1093/function/zqab065] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 01/07/2023]
Abstract
ATP synthase (F1Fo) synthesizes daily our body's weight in ATP, whose production-rate can be transiently increased several-fold to meet changes in energy utilization. Using purified mammalian F1Fo-reconstituted proteoliposomes and isolated mitochondria, we show F1Fo can utilize both ΔΨm-driven H+- and K+-transport to synthesize ATP under physiological pH = 7.2 and K+ = 140 mEq/L conditions. Purely K+-driven ATP synthesis from single F1Fo molecules measured by bioluminescence photon detection could be directly demonstrated along with simultaneous measurements of unitary K+ currents by voltage clamp, both blocked by specific Fo inhibitors. In the presence of K+, compared to osmotically-matched conditions in which this cation is absent, isolated mitochondria display 3.5-fold higher rates of ATP synthesis, at the expense of 2.6-fold higher rates of oxygen consumption, these fluxes being driven by a 2.7:1 K+: H+ stoichiometry. The excellent agreement between the functional data obtained from purified F1Fo single molecule experiments and ATP synthase studied in the intact mitochondrion under unaltered OxPhos coupling by K+ presence, is entirely consistent with K+ transport through the ATP synthase driving the observed increase in ATP synthesis. Thus, both K+ (harnessing ΔΨm) and H+ (harnessing its chemical potential energy, ΔμH) drive ATP generation during normal physiology.
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Affiliation(s)
| | | | | | | | | | - Kenneth W Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Lluis Montoliu
- National Centre for Biotechnology (CNB-CSIC), Biomedical Research Networking Center on Rare Diseases (CIBERER-ISCIII), 28049, Madrid, Spain
| | - Sandra B Gabelli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA,Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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Chen J, Luo Y, Cao J, Xie L. Fluoride exposure changed the expression of microRNAs in gills of male zebrafish (Danio rerio). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 233:105789. [PMID: 33667915 DOI: 10.1016/j.aquatox.2021.105789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/19/2021] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
Fluoride has been found to cause detrimental effects on fish gills. Despite essential roles in various metabolism activities, whether and how miRNAs participate in the course of toxicity caused by fluoride in gills is still unclear. In this study, male zebrafish were exposed to 0, 20, 40 mg/L fluoride for 60 days to study the underlying osmotic regulatory mechanism by determining the influences of fluoride on the miRNAs and regulated genes in gills. mRNAs were isolated from the gills and the expression profiles were analyzed by using Illumina Hiseq 2500 platforms. Expressions of 7 differentially miRNAs and some related-genes in gills were validated by qRT-PCR. The results showed that miRNAs expressions were notably altered by fluoride. A total of 584 and 327 miRNAs were remarkably changed after 20 and 40 mg/L fluoride exposure, of which 322 were increased and 262 were decreased in 20 mg/L fluoride group, whereas 219 were elevated and 108 were reduced in 40 mg/L fluoride group. The differentially expressive miRNAs confirmed by qRT-PCR were consistent with micro-assay data. Cluster of Orthologous Groups of proteins (COG) function classification showed that the target genes of differentially expressive miRNAs are mainly related to signal transduction mechanisms, replication, transcription, inorganic ion transport and metabolism, repair and recombination, and energy formation and transformation. In addition, fluoride disturbed the expressions of target genes involved in the osmoregulation of the gill in the fluoride-exposed zebrafish, such as the increased expressions of OSTF1 and the decreased expressions of Na+-K+-ATPase, CFTR, and AQP-3, which provides a possibility that miRNAs regulation induced by fluoride has an effects on osmotic regulation, providing new hints to the osmotic regulatory mechanism of the toxicity caused by fluoride in zebrafish, and distinguishes new biomarkers of miRNAs for fluoride toxicity.
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Affiliation(s)
- Jianjie Chen
- College of Veterinary Medicine, Shanxi Agricultural University, Taigu, Shanxi, 030801, China
| | - Yongju Luo
- Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Science, Nanning, Guangxi, 530021, China
| | - Jinling Cao
- College of Food Science and Technology, Shanxi Agricultural University, Taigu, Shanxi, 030801, China.
| | - Lingtian Xie
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Environmental Theoretical Chemistry, South China Normal University, Guangzhou, 510006, China.
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11
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Li J, Xu Y, Song Q, Zhang S, Xie L, Yang J. Transmembrane transport mechanism of n-hexadecane by Candida tropicalis: Kinetic study and proteomic analysis. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 209:111789. [PMID: 33340957 DOI: 10.1016/j.ecoenv.2020.111789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/27/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Yeasts are the most predominant petroleum hydrocarbon-degrading fungi isolated from petroleum-contaminated soil. However, information of the transmembrane transport of petroleum hydrocarbon into yeast cells is limited. The present study was designed to explore the transmembrane transport mechanisms of the typical petroleum hydrocarbon n-hexadecane in Candida tropicalis cells with petroleum hydrocarbon biodegradation potential. Yeast cells were treated with n-hexadecane in different scenarios, and the percentage of intracellular n-hexadecane and transport dynamics were investigated accordingly. The intracellular concentration of n-hexadecane increased within 15 min, and transportation was inhibited by NaN3, an ATPase inhibitor. The uptake kinetics of n-hexadecane were well fitted by the Michaelis-Menten model, and Kt values ranged from 152.49 to 194.93 mg/L. All these findings indicated that n-hexadecane might cross the yeast cells in an energy-dependent manner and exhibit an affinity with the cell transport system. Moreover, the differentially expressed membrane proteins induced by n-hexadecane were identified and quantified by tandem mass tag labeling coupled with liquid chromatography tandem mass spectrometry analysis. The proteome analysis results demonstrated that energy production and conversion accounted for a large proportion of the functional classifications of the differentially expressed proteins, providing further evidence that sufficient energy supply is essential for transmembrane transport. Protein functional analysis also suggested that differentially expressed proteins associated with transmembrane transport processes are clearly enriched in endocytosis and phagosome pathways (p < 0.05), and the analysis supported the notion that the underlying transmembrane transport mechanism might be associated with endocytosis and phagosome pathways, revealing a new mechanism of n-hexadecane internalization by Candida tropicalis.
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Affiliation(s)
- Jian Li
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China.
| | - Ying Xu
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Quanwei Song
- State Key Laboratory of Petroleum Pollution Control, Beijing 102206, China
| | - Shurong Zhang
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Lin Xie
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China
| | - Jie Yang
- Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing 100875, China.
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12
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Kusunoki S, Kido J, Momosaki K, Sawada T, Kashiki T, Matsumoto S, Nakamura K. Effect of Flunarizine on Alternating Hemiplegia of Childhood in a Patient with the p.E815K Mutation in ATP1A3: A Case Report. Case Rep Neurol 2020; 12:299-306. [PMID: 33082768 PMCID: PMC7548950 DOI: 10.1159/000509287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/04/2020] [Indexed: 11/19/2022] Open
Abstract
Alternating hemiplegia of childhood (AHC) (MIM 104290) is characterized by transient repeated attacks of paresis on either or both sides of the body, oculomotor and autonomic abnormalities, movement disorders, and cognitive impairment. Preventing paroxysmal attacks, such as paresis and spasm, in patients with AHC is often difficult. An 8-month-old girl presented to our institution with intractable epilepsy. She developed AHC, with left-right alternating or bilateral recurrent plegia upon waking, involuntary movements, eye movement abnormalities, and psychomotor retardation. She had a heterozygous de novo p.E815K mutation in the <i>ATP1A3</i>gene. Patients with this mutation develop severe hemiplegic spells and convulsions, have a poor neuromotor developmental outcome, and are particularly difficult to treat. Flunarizine treatment has limited therapeutic effect in such patients; however, it was definitely effective for bulbar palsy in the present case. The present case further highlights the need for the development of other new treatments, such as a ketogenic diet.
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Affiliation(s)
| | - Jun Kido
- *Jun Kido, Department of Pediatrics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto City, Kumamoto 860-8556 (Japan),
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13
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Ahad MA, Kumaran KR, Ning T, Mansor NI, Effendy MA, Damodaran T, Lingam K, Wahab HA, Nordin N, Liao P, Müller CP, Hassan Z. Insights into the neuropathology of cerebral ischemia and its mechanisms. Rev Neurosci 2020; 31:521-538. [DOI: 10.1515/revneuro-2019-0099] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/09/2020] [Indexed: 11/15/2022]
Abstract
AbstractCerebral ischemia is a result of insufficient blood flow to the brain. It leads to limited supply of oxygen and other nutrients to meet metabolic demands. These phenomena lead to brain damage. There are two types of cerebral ischemia: focal and global ischemia. This condition has significant impact on patient’s health and health care system requirements. Animal models such as transient occlusion of the middle cerebral artery and permanent occlusion of extracranial vessels have been established to mimic the conditions of the respective type of cerebral ischemia and to further understand pathophysiological mechanisms of these ischemic conditions. It is important to understand the pathophysiology of cerebral ischemia in order to identify therapeutic strategies for prevention and treatment. Here, we review the neuropathologies that are caused by cerebral ischemia and discuss the mechanisms that occur in cerebral ischemia such as reduction of cerebral blood flow, hippocampal damage, white matter lesions, neuronal cell death, cholinergic dysfunction, excitotoxicity, calcium overload, cytotoxic oedema, a decline in adenosine triphosphate (ATP), malfunctioning of Na+/K+-ATPase, and the blood-brain barrier breakdown. Altogether, the information provided can be used to guide therapeutic strategies for cerebral ischemia.
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Affiliation(s)
- Mohamad Anuar Ahad
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Kesevan Rajah Kumaran
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Tiang Ning
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Nur Izzati Mansor
- Medical Genetics Unit, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | | | - Thenmoly Damodaran
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Kamilla Lingam
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Habibah Abdul Wahab
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang, Malaysia
- USM-RIKEN Centre for Aging Science (URICAS), Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
| | - Norshariza Nordin
- Medical Genetics Unit, Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
- Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Ping Liao
- Calcium Signaling Laboratory, National Neuroscience Institute, Singapore 308433, Singapore
| | - Christian P. Müller
- Section of Addiction Medicine, Department of Psychiatry and Psychotherapy, University Clinic, Friedrich Alexander University Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Zurina Hassan
- Centre for Drug Research, Universiti Sains Malaysia, 11800 Penang, Malaysia
- USM-RIKEN Centre for Aging Science (URICAS), Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
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14
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Moreno C, Yano S, Bezanilla F, Latorre R, Holmgren M. Transient Electrical Currents Mediated by the Na +/K +-ATPase: A Tour from Basic Biophysics to Human Diseases. Biophys J 2020; 119:236-242. [PMID: 32579966 PMCID: PMC7376075 DOI: 10.1016/j.bpj.2020.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/06/2020] [Accepted: 06/03/2020] [Indexed: 01/14/2023] Open
Abstract
The Na+/K+-ATPase is a chemical molecular machine responsible for the movement of Na+ and K+ ions across the cell membrane. These ions are moved against their electrochemical gradients, so the protein uses the free energy of ATP hydrolysis to transport them. In fact, the Na+/K+-ATPase is the single largest consumer of energy in most cells. In each pump cycle, the protein sequentially exports 3Na+ out of the cell, then imports 2K+ into the cell at an approximate rate of 200 cycles/s. In each half cycle of the transport process, there is a state in which ions are stably trapped within the permeation pathway of the protein by internal and external gates in their closed states. These gates are required to open alternately; otherwise, passive ion diffusion would be a wasteful end of the cell's energy. Once one of these gates open, ions diffuse from their binding sites to the accessible milieu, which involves moving through part of the electrical field across the membrane. Consequently, ions generate transient electrical currents first discovered more than 30 years ago. They have been studied in a variety of preparations, including native and heterologous expression systems. Here, we review three decades' worth of work using these transient electrical signals to understand the kinetic transitions of the movement of Na+ and K+ ions through the Na+/K+-ATPase and propose the significance that this work might have to the understanding of the dysfunction of human pump orthologs responsible for some newly discovered neurological pathologies.
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Affiliation(s)
- Cristina Moreno
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Sho Yano
- Medical Genetics and Genomic Medicine Training Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, University of Chicago, Gordon Center for Integrative Sciences, Chicago, Illinois
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Miguel Holmgren
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland.
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15
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Multipurpose Na + ions mediate excitation and cellular homeostasis: Evolution of the concept of Na + pumps and Na +/Ca 2+ exchangers. Cell Calcium 2020; 87:102166. [PMID: 32006802 DOI: 10.1016/j.ceca.2020.102166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/14/2022]
Abstract
Ionic signalling is the most ancient form of regulation of cellular functions in response to environmental challenges. Signals, mediated by Na+ fluxes and spatio-temporal fluctuations of Na+ concentration in cellular organelles and cellular compartments contribute to the most fundamental cellular processes such as membrane excitability and energy production. At the very core of ionic signalling lies the Na+-K+ ATP-driven pump (or NKA) which creates trans-plasmalemmal ion gradients that sustain ionic fluxes through ion channels and numerous Na+-dependent transporters that maintain cellular and tissue homeostasis. Here we present a brief account of the history of research into NKA, Na+ -dependent transporters and Na+ signalling.
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16
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Fernández ÁF, Liu Y, Ginet V, Shi M, Nah J, Zou Z, Zhou A, Posner BA, Xiao G, Tanguy M, Paradis V, Sadoshima J, Rautou PE, Puyal J, Hu MC, Levine B. Interaction between the autophagy protein Beclin 1 and Na+,K+-ATPase during starvation, exercise, and ischemia. JCI Insight 2020; 5:133282. [PMID: 31941841 DOI: 10.1172/jci.insight.133282] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/04/2019] [Indexed: 01/26/2023] Open
Abstract
Autosis is a distinct form of cell death that requires both autophagy genes and the Na+,K+-ATPase pump. However, the relationship between the autophagy machinery and Na+,K+-ATPase is unknown. We explored the hypothesis that Na+,K+-ATPase interacts with the autophagy protein Beclin 1 during stress and autosis-inducing conditions. Starvation increased the Beclin 1/Na+,K+-ATPase interaction in cultured cells, and this was blocked by cardiac glycosides, inhibitors of Na+,K+-ATPase. Increases in Beclin 1/Na+,K+-ATPase interaction were also observed in tissues from starved mice, livers of patients with anorexia nervosa, brains of neonatal rats subjected to cerebral hypoxia-ischemia (HI), and kidneys of mice subjected to renal ischemia/reperfusion injury (IRI). Cardiac glycosides blocked the increased Beclin 1/Na+,K+-ATPase interaction during cerebral HI injury and renal IRI. In the mouse renal IRI model, cardiac glycosides reduced numbers of autotic cells in the kidney and improved clinical outcome. Moreover, blockade of endogenous cardiac glycosides increased Beclin 1/Na+,K+-ATPase interaction and autotic cell death in mouse hearts during exercise. Thus, Beclin 1/Na+,K+-ATPase interaction is increased in stress conditions, and cardiac glycosides decrease this interaction and autosis in both pathophysiological and physiological settings. This crosstalk between cellular machinery that generates and consumes energy during stress may represent a fundamental homeostatic mechanism.
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Affiliation(s)
- Álvaro F Fernández
- Center for Autophagy Research.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Yang Liu
- Center for Autophagy Research.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Vanessa Ginet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Mingjun Shi
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jihoon Nah
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Zhongju Zou
- Center for Autophagy Research.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Howard Hughes Medical Institute
| | | | | | - Guanghua Xiao
- Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Marion Tanguy
- Centre de Recherche sur l'Inflammation, Université de Paris, Paris, France.,Service d'Hépatologie, Pôle des Maladies de l'Appareil Digestif, Département Hospitalo-Universitaire Unity, and
| | - Valérie Paradis
- Centre de Recherche sur l'Inflammation, Université de Paris, Paris, France.,Service d'Anatomie Pathologique, Hôpital Beaujon, Assistance Hôpitaux Publique de Paris, Clichy, France
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Pierre-Emmanuel Rautou
- Centre de Recherche sur l'Inflammation, Université de Paris, Paris, France.,Service d'Hépatologie, Pôle des Maladies de l'Appareil Digestif, Département Hospitalo-Universitaire Unity, and
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Beth Levine
- Center for Autophagy Research.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Howard Hughes Medical Institute
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17
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Munkert J, Gomes ER, Marostica LL, Cota BB, Lopes CLM, Andrade SF, Filho JDS, Alves RJ, Oliveira MC, Braga FC, Simões CO, Pádua RM, de Barros ALB. New 99mTc-Labeled Digitoxigenin Derivative for Cancer Cell Identification. ACS OMEGA 2019; 4:22048-22056. [PMID: 31891085 PMCID: PMC6933791 DOI: 10.1021/acsomega.9b03167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
In recent years, cardiac glycosides (CGs) have been investigated as potential antiviral and anticancer drugs. Digitoxigenin (DIG) and other CGs have been shown to bind and inhibit Na+/K+-adenosinetriphosphatase (ATPase). Tumor cells show a higher expression rate of the Na+/K+-ATPase protein or a stronger affinity towards the binding of CGs and are therefore more prone to CGs than non-tumor cells. Cancer imaging techniques using radiotracers targeted at specific receptors have yielded successful results. Technetium-99m (99mTc) is one of the radionuclides of choice to radiolabel pharmaceuticals because of its favorable physical and chemical properties along with reasonable costs. Herein, we describe a new Na+/K+-ATPase targeting radiotracer consisting of digitoxigenin and diethylenetriaminepentaacetic acid (DTPA), a bifunctional chelating ligand used to prepare 99mTc-labeled complexes, and its evaluation as an imaging probe. We report the synthesis and characterization of the radiolabeled compound including stability tests, blood clearance, and biodistribution in healthy mice. Additionally, we investigated the binding of the compound to A549 human non-small-cell lung cancer cells and the inhibition of the Na+/K+-ATPase by the labeled compound in vitro. The 99mTc-labeled DTPA-digitoxigenin (99mTc-DTPA-DIG) compound displayed high stability in vitro and in vivo, a fast renal excretion, and a specific binding towards A549 cancer cells in comparison to non-tumor cells. Therefore, 99mTc-DTPA-DIG could potentially be used for non-invasive visualization of tumor lesions by means of scintigraphic imaging.
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Affiliation(s)
- Jennifer Munkert
- Department
of Biology, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Staudtstrasse 5, 91058 Erlangen, Germany
| | - Eliza R. Gomes
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Lucas L. Marostica
- Department
of Pharmaceutical Sciences, Universidade
Federal de Santa Catarina, Florianópolis, SC 88040-970, Brazil
| | - Betânia B. Cota
- Laboratório
de Química de Produtos Naturais Bioativos, Centro de Pesquisa René Rachou, Fundação Oswaldo
Cruz, Av. Augusto de
Lima, 1715, Belo Horizonte, MG 30190-002, Brazil
| | - Cristina L. M. Lopes
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Saulo F. Andrade
- Faculty
of
Pharmaceutical Sciences, Universidade Federal
de Rio Grande do Sul, Av. Ipiranga, 2752, Porto Alegre, RS 90610-000, Brazil
| | - José
D. de Souza Filho
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Ricardo J. Alves
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Monica C. Oliveira
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Fernão C. Braga
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - Cláudia
M. O. Simões
- Department
of Pharmaceutical Sciences, Universidade
Federal de Santa Catarina, Florianópolis, SC 88040-970, Brazil
| | - Rodrigo M. Pádua
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
| | - André L. B. de Barros
- Faculty
of Pharmacy and Department of Chemistry, Universidade Federal
de Minas Gerais, Av. Pres. Antônio Carlos, 6627, Belo
Horizonte, MG 31270-901, Brazil
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18
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Askari A. The other functions of the sodium pump. Cell Calcium 2019; 84:102105. [DOI: 10.1016/j.ceca.2019.102105] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/21/2019] [Accepted: 10/28/2019] [Indexed: 01/14/2023]
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19
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External Ion Access in the Na/K Pump: Kinetics of Na +, K +, and Quaternary Amine Interaction. Biophys J 2019; 115:361-374. [PMID: 30021111 DOI: 10.1016/j.bpj.2018.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/18/2018] [Accepted: 06/06/2018] [Indexed: 11/23/2022] Open
Abstract
Na/K pumps build essential ion gradients across the plasmalemma of animal cells by coupling the extrusion of three Na+, with the import of two K+ and the hydrolysis of one ATP molecule. The mechanisms of selectivity and competition between Na+, K+, and inhibitory amines remain unclear. We measured the effects of external tetrapropylammonium (TPA+) and ethylenediamine (EDA2+) on three different Na/K pump transport modes in voltage-clamped Xenopus oocytes: 1) outward pump current (IP), 2) passive inward H+ current at negative voltages without Na+ or K+ (IH), and 3) transient charge movement reporting the voltage-dependent extracellular binding/release of Na+ (QNa). Both amines competed with K+ to inhibit IP. TPA+ inhibited IH without competing with H+, whereas EDA2+ did not alter IH at pH 7.6. TPA+ competed with Na+ in QNa measurements, reducing Na+-apparent affinity, evidenced by a ∼-75 mV shift in the charge-voltage curve (at 20 mM TPA+) without reduction of the total charge moved (Qtot). In contrast, EDA2+ and K+ did not compete with Na+ to inhibit QNa; both reduced Qtot without decreasing Na+-apparent affinity. EDA2+ (15 mM) right-shifted the charge-voltage curve by ∼+50 mV. Simultaneous occlusion of EDA2+ and Na+ by an E2P conformation unable to reach E1P was demonstrated by voltage-clamp fluorometry. Trypsinolysis experiments showed that EDA2+-bound pumps are much more proteolysis-resistant than Na+-, K+-, or TPA+-bound pumps, therefore uncovering unique EDA2+-bound conformations. K+ effects on QNa and IH were also evaluated in pumps inhibited with beryllium fluoride, a phosphate mimic. K+ reduced Qtot without shifting the charge-voltage curve, indicating noncompetitive effects, and partially inhibited IH to the same extent as TPA+ in non-beryllium-fluorinated pumps. These results demonstrate that K+ interacts with beryllium-fluorinated pumps inducing conformational changes that alter QNa and IH, suggesting that there are two external access pathways for proton transport by IH.
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20
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Burton AG, Hopper K. Hyponatremia in dogs and cats. J Vet Emerg Crit Care (San Antonio) 2019; 29:461-471. [DOI: 10.1111/vec.12881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/04/2017] [Accepted: 09/06/2017] [Indexed: 01/10/2023]
Affiliation(s)
| | - Kate Hopper
- Department of Veterinary Surgical and Radiological SciencesUniversity of California Davis CA
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21
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Sampedro Castañeda M, Zanoteli E, Scalco RS, Scaramuzzi V, Marques Caldas V, Conti Reed U, da Silva AMS, O'Callaghan B, Phadke R, Bugiardini E, Sud R, McCall S, Hanna MG, Poulsen H, Männikkö R, Matthews E. A novel ATP1A2 mutation in a patient with hypokalaemic periodic paralysis and CNS symptoms. Brain 2019; 141:3308-3318. [PMID: 30423015 PMCID: PMC6262219 DOI: 10.1093/brain/awy283] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 09/25/2018] [Indexed: 01/26/2023] Open
Abstract
Hypokalaemic periodic paralysis is a rare genetic neuromuscular disease characterized by episodes of skeletal muscle paralysis associated with low serum potassium. Muscle fibre inexcitability during attacks of paralysis is due to an aberrant depolarizing leak current through mutant voltage sensing domains of either the sarcolemmal voltage-gated calcium or sodium channel. We report a child with hypokalaemic periodic paralysis and CNS involvement, including seizures, but without mutations in the known periodic paralysis genes. We identified a novel heterozygous de novo missense mutation in the ATP1A2 gene encoding the α2 subunit of the Na+/K+-ATPase that is abundantly expressed in skeletal muscle and in brain astrocytes. Pump activity is crucial for Na+ and K+ homeostasis following sustained muscle or neuronal activity and its dysfunction is linked to the CNS disorders hemiplegic migraine and alternating hemiplegia of childhood, but muscle dysfunction has not been reported. Electrophysiological measurements of mutant pump activity in Xenopus oocytes revealed lower turnover rates in physiological extracellular K+ and an anomalous inward leak current in hypokalaemic conditions, predicted to lead to muscle depolarization. Our data provide important evidence supporting a leak current as the major pathomechanism underlying hypokalaemic periodic paralysis and indicate ATP1A2 as a new hypokalaemic periodic paralysis gene.
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Affiliation(s)
- Marisol Sampedro Castañeda
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Edmar Zanoteli
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Renata S Scalco
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Vinicius Scaramuzzi
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Vitor Marques Caldas
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Umbertina Conti Reed
- Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | | | - Benjamin O'Callaghan
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Rahul Phadke
- Division of Neuropathology, UCL Institute of Neurology, London, UK
| | - Enrico Bugiardini
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Richa Sud
- Neurogenetics Unit, UCL Institute of Neurology, Queen Square, London, UK
| | - Samuel McCall
- Neurogenetics Unit, UCL Institute of Neurology, Queen Square, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Hanne Poulsen
- DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, DK-8000 Aarhus, Denmark
| | - Roope Männikkö
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, UK
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22
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Meyer DJ, Gatto C, Artigas P. Na/K Pump Mutations Associated with Primary Hyperaldosteronism Cause Loss of Function. Biochemistry 2019; 58:1774-1785. [PMID: 30811176 DOI: 10.1021/acs.biochem.9b00051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Primary hyperaldosteronism (Conn's syndrome), a common cause of secondary hypertension, is frequently produced by unilateral aldosterone-producing adenomas that carry mutations in ion-transporting genes, including ATP1A1, encoding the Na/K pump's α1 subunit. Whether Na/K pump mutant-mediated inward currents are required to depolarize the cell and increase aldosterone production remains unclear, as such currents were observed in four out of five mutants described so far. Here, we use electrophysiology and uptake of the K+ congener 86Rb+, to characterize the effects of eight additional Na/K pump mutations in transmembrane segments TM1 (delM102-L103, delL103-L104, and delM102-I106), TM4 (delI322-I325 and I327S), and TM9 (delF956-E961, delF959-E961, and delE960-L964), expressed in Xenopus oocytes. All deletion mutants induced abnormal inward currents of different amplitudes at physiological voltages, while I327S lacked such currents. A detailed functional characterization revealed that I327S significantly reduces intracellular Na+ affinity without altering affinity for external K+. 86Rb+-uptake experiments show that I327S dramatically impairs function under physiological concentrations of Na+ and K+. Since Na/K pumps in the adrenal cortex may be formed by association of α1 with β3 instead of β1 subunits, we evaluated whether G99R (another mutant without inward currents when associated with β1) would show inward currents when associated with β3. We found that the kinetic characteristics of either mutant or wild-type α1β3 pumps expressed in Xenopus oocytes to be indistinguishable from those of α1β1 pumps. The observed functional consequences of each hyperaldosteronism mutant point to the loss of Na/K pump function as the common feature of all mutants, which is sufficient to induce hyperaldosteronism.
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Affiliation(s)
- Dylan J Meyer
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research , Texas Tech University Health Sciences Center , Lubbock , Texas 79430 , United States
| | - Craig Gatto
- School of Biological Sciences , Illinois State University , Normal , Illinois 61790 , United States
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research , Texas Tech University Health Sciences Center , Lubbock , Texas 79430 , United States
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23
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Roenn CP, Li M, Schack VR, Forster IC, Holm R, Toustrup-Jensen MS, Andersen JP, Petrou S, Vilsen B. Functional consequences of the CAPOS mutation E818K of Na +,K +-ATPase. J Biol Chem 2018; 294:269-280. [PMID: 30409907 DOI: 10.1074/jbc.ra118.004591] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/04/2018] [Indexed: 11/06/2022] Open
Abstract
The cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) syndrome is caused by the single mutation E818K of the α3-isoform of Na+,K+-ATPase. Here, using biochemical and electrophysiological approaches, we examined the functional characteristics of E818K, as well as of E818Q and E818A mutants. We found that these amino acid substitutions reduce the apparent Na+ affinity at the cytoplasmic-facing sites of the pump protein and that this effect is more pronounced for the lysine and glutamine substitutions (3-4-fold) than for the alanine substitution. The electrophysiological measurements indicated a more conspicuous, ∼30-fold reduction of apparent Na+ affinity for the extracellular-facing sites in the CAPOS mutant, which was related to an accelerated transition between the phosphoenzyme intermediates E1P and E2P. The apparent affinity for K+ activation of the ATPase activity was unaffected by these substitutions, suggesting that primarily the Na+-specific site III is affected. Furthermore, the apparent affinities for ATP and vanadate were WT-like in E818K, indicating a normal E1-E2 equilibrium of the dephosphoenzyme. Proton-leak currents were not increased in E818K. However, the CAPOS mutation caused a weaker voltage dependence of the pumping rate and a stronger inhibition by cytoplasmic K+ than the WT enzyme, which together with the reduced Na+ affinity of the cytoplasmic-facing sites precluded proper pump activation under physiological conditions. The functional deficiencies could be traced to the participation of Glu-818 in an intricate hydrogen-bonding/salt-bridge network, connecting it to key residues involved in Na+ interaction at site III.
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Affiliation(s)
- Christian P Roenn
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Melody Li
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Vivien R Schack
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ian C Forster
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Rikke Holm
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | | | - Jens P Andersen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
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24
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Cornelius F, Tsunekawa N, Toyoshima C. Distinct pH dependencies of Na +/K + selectivity at the two faces of Na,K-ATPase. J Biol Chem 2017; 293:2195-2205. [PMID: 29247005 DOI: 10.1074/jbc.ra117.000700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/28/2017] [Indexed: 11/06/2022] Open
Abstract
The sodium pump (Na,K-ATPase) in animal cells is vital for actively maintaining ATP hydrolysis-powered Na+ and K+ electrochemical gradients across the cell membrane. These ion gradients drive co- and countertransport and are critical for establishing the membrane potential. It has been an enigma how Na,K-ATPase discriminates between Na+ and K+, despite the pumped ion on each side being at a lower concentration than the other ion. Recent crystal structures of analogs of the intermediate conformations E2·Pi·2K+ and Na+-bound E1∼P·ADP suggest that the dimensions of the respective binding sites in Na,K-ATPase are crucial in determining its selectivity. Here, we found that the selectivity at each membrane face is pH-dependent and that this dependence is unique for each face. Most notable was a strong increase in the specific affinity for K+ at the extracellular face (i.e. E2 conformation) as the pH is lowered from 7.5 to 5. We also observed a smaller increase in affinity for K+ on the cytoplasmic side (E1 conformation), which reduced the selectivity for Na+ Theoretical analysis of the pKa values of ion-coordinating acidic amino acid residues suggested that the face-specific pH dependences and Na+/K+ selectivities may arise from the protonation or ionization of key residues. The increase in K+ selectivity at low pH on the cytoplasmic face, for instance, appeared to be associated with Asp808 protonation. We conclude that changes in the ionization state of coordinating residues in Na,K-ATPase could contribute to altering face-specific ion selectivity.
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Affiliation(s)
- Flemming Cornelius
- From the Department of Biomedicine, University of Aarhus, Ole Worms Allé 6, 8000 Aarhus C, Denmark and
| | - Naoki Tsunekawa
- the Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032
| | - Chikashi Toyoshima
- the Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032
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25
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Abstract
Insufficient sodium-ion extrusion by mutated Na+,K+-ATPases causes hyperaldosteronism.
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26
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Meyer DJ, Gatto C, Artigas P. On the effect of hyperaldosteronism-inducing mutations in Na/K pumps. J Gen Physiol 2017; 149:1009-1028. [PMID: 29030398 PMCID: PMC5677107 DOI: 10.1085/jgp.201711827] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 11/29/2022] Open
Abstract
Mutated Na/K pumps in adrenal adenomas are thought to cause hyperaldosteronism via a gain-of-function effect involving a depolarizing inward current. The findings of Meyer et al. suggest instead that the common mechanism by which Na/K pump mutants lead to hyperaldosteronism is a loss-of-function. Primary aldosteronism, a condition in which too much aldosterone is produced and that leads to hypertension, is often initiated by an aldosterone-producing adenoma within the zona glomerulosa of the adrenal cortex. Somatic mutations of ATP1A1, encoding the Na/K pump α1 subunit, have been found in these adenomas. It has been proposed that a passive inward current transported by several of these mutant pumps is a "gain-of-function" activity that produces membrane depolarization and concomitant increases in aldosterone production. Here, we investigate whether the inward current through mutant Na/K pumps is large enough to induce depolarization of the cells that harbor them. We first investigate inward currents induced by these mutations in Xenopus Na/K pumps expressed in Xenopus oocytes and find that these inward currents are similar in amplitude to wild-type outward Na/K pump currents. Subsequently, we perform a detailed functional evaluation of the human Na/K pump mutants L104R, delF100-L104, V332G, and EETA963S expressed in Xenopus oocytes. By combining two-electrode voltage clamp with [3H]ouabain binding, we measure the turnover rate of these inward currents and compare it to the turnover rate for outward current through wild-type pumps. We find that the turnover rate of the inward current through two of these mutants (EETA963S and L104R) is too small to induce significant cell depolarization. Electrophysiological characterization of another hyperaldosteronism-inducing mutation, G99R, reveals the absence of inward currents under many different conditions, including in the presence of the regulator FXYD1 as well as with mammalian ionic concentrations and body temperatures. Instead, we observe robust outward currents, but with significantly reduced affinities for intracellular Na+ and extracellular K+. Collectively, our results point to loss-of-function as the common mechanism for the hyperaldosteronism induced by these Na/K pump mutants.
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Affiliation(s)
- Dylan J Meyer
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX.,School of Biological Sciences, Illinois State University, Normal, IL
| | - Craig Gatto
- School of Biological Sciences, Illinois State University, Normal, IL
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX
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27
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Intracellular Requirements for Passive Proton Transport through the Na +,K +-ATPase. Biophys J 2017; 111:2430-2439. [PMID: 27926844 DOI: 10.1016/j.bpj.2016.09.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/26/2016] [Accepted: 09/28/2016] [Indexed: 11/21/2022] Open
Abstract
The Na+,K+-ATPase (NKA or Na/K pump) hydrolyzes one ATP to exchange three intracellular Na+ (Na+i) for two extracellular K+ (K+o) across the plasma membrane by cycling through a set of reversible transitions between phosphorylated and dephosphorylated conformations, alternately opening ion-binding sites externally (E2) or internally (E1). With subsaturating [Na+]o and [K+]o, the phosphorylated E2P conformation passively imports protons generating an inward current (IH), which may be exacerbated in NKA-subunit mutations associated with human disease. To elucidate the mechanisms of IH, we studied the effects of intracellular ligands (transported ions, nucleotides, and beryllium fluoride) on IH and, for comparison, on transient currents measured at normal Na+o (QNa). Utilizing inside-out patches from Xenopus oocytes heterologously expressing NKA, we observed that 1) in the presence of Na+i, IH and QNa were both activated by ATP, but not ADP; 2) the [Na+]i dependence of IH in saturating ATP showed K0.5,Na = 1.8 ± 0.2 mM and the [ATP] dependence at saturating [Na+]i yielded K0.5,ATP = 48 ± 11 μM (in comparison, Na+i-dependent QNa yields K0.5,Na = 0.8 ± 0.2 mM and K0.5,ATP = 0.43 ± 0.03 μM; 3) ATP activated IH in the presence of K+i (∼15% of the IH observed in Na+i) only when Mg2+i was also present; and 4) beryllium fluoride induced maximal IH even in the absence of nucleotide. These data indicate that IH occurs when NKA is in an externally open E2P state with nucleotide bound, a conformation that can be reached through forward Na/K pump phosphorylation of E1, with Na+i and ATP, or by backward binding of K+i to E1, which drives the pump to the occluded E2(2K), where free Pi (at the micromolar levels found in millimolar ATP solutions) promotes external release of occluded K+ by backdoor NKA phosphorylation. Maximal IH through beryllium-fluorinated NKA indicates that this complex mimics ATP-bound E2P states.
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28
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Isaksen TJ, Kros L, Vedovato N, Holm TH, Vitenzon A, Gadsby DC, Khodakhah K, Lykke-Hartmann K. Hypothermia-induced dystonia and abnormal cerebellar activity in a mouse model with a single disease-mutation in the sodium-potassium pump. PLoS Genet 2017; 13:e1006763. [PMID: 28472154 PMCID: PMC5436892 DOI: 10.1371/journal.pgen.1006763] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 05/18/2017] [Accepted: 04/17/2017] [Indexed: 11/18/2022] Open
Abstract
Mutations in the neuron-specific α3 isoform of the Na+/K+-ATPase are found in patients suffering from Rapid onset Dystonia Parkinsonism and Alternating Hemiplegia of Childhood, two closely related movement disorders. We show that mice harboring a heterozygous hot spot disease mutation, D801Y (α3+/D801Y), suffer abrupt hypothermia-induced dystonia identified by electromyographic recordings. Single-neuron in vivo recordings in awake α3+/D801Y mice revealed irregular firing of Purkinje cells and their synaptic targets, the deep cerebellar nuclei neurons, which was further exacerbated during dystonia and evolved into abnormal high-frequency burst-like firing. Biophysically, we show that the D-to-Y mutation abolished pump-mediated Na+/K+ exchange, but allowed the pumps to bind Na+ and become phosphorylated. These findings implicate aberrant cerebellar activity in α3 isoform-related dystonia and add to the functional understanding of the scarce and severe mutations in the α3 isoform Na+/K+-ATPase. The neurological spectrum associated with mutations in the ATP1A3 gene, encoding the α3 isoform of the Na+/K+-ATPase, is complex and still poorly understood. To elucidate the disease-specific pathophysiology, we examined a mouse model harboring the mutation D801Y, which was originally found in a patient with Rapid onset Dystonia Parkinsonism, but recently, also in a patient with Alternating Hemiplegia of Childhood. We found that this model exhibited motor deficits and developed dystonia when exposed to a drop in body temperature. Cerebellar in vivo recordings in awake mice revealed irregular firing of Purkinje cells and their synaptic targets, the deep cerebellar nuclei neurons, which was further exacerbated and evolved into abnormal high-frequency burst firing during dystonia. The development of specific neurological features within the ATP1A3 mutation spectrum, such as dystonia, are thought to reflect the functional consequences of each mutation, thus to investigate the consequence of the D801Y mutations we characterized mutated D-to-Y Na+/K+-ATPases expressed in Xenopus oocytes. These in vitro studies showed that the D-to-Y mutation abolishes pump-mediated Na+/K+ exchange, but still allows the pumps to bind Na+ and become phosphorylated, trapping them in conformations that instead support proton influx.
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Affiliation(s)
- Toke Jost Isaksen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Lieke Kros
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Natascia Vedovato
- The Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York, United States of America
| | - Thomas Hellesøe Holm
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Ariel Vitenzon
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - David C. Gadsby
- The Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York, United States of America
| | - Kamran Khodakhah
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Karin Lykke-Hartmann
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- * E-mail:
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29
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Pedersen JT, Palmgren M. Why do plants lack sodium pumps and would they benefit from having one? FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:473-479. [PMID: 32480580 DOI: 10.1071/fp16422] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 01/31/2017] [Indexed: 05/26/2023]
Abstract
The purpose of this minireview is to discuss the feasibility of creating a new generation of salt-tolerant plants that express Na+/K+-ATPases from animals or green algae. Attempts to generate salt-tolerant plants have focussed on increase the expression of or introducing salt stress-related genes from plants, bryophytes and yeast. Even though these approaches have resulted in plants with increased salt tolerance, plant growth is decreased under salt stress and often also under normal growth conditions. New strategies to increase salt tolerance are therefore needed. Theoretically, plants transformed with an animal-type Na+/K+-ATPase should not only display a high degree of salt tolerance but should also reduce the stress response exhibited by the first generation of salt-tolerant plants under both normal and salt stress conditions. The biological feasibility of such a strategy of producing transgenic plants that display improved growth on saline soil but are indistinguishable from wild-type plants under normal growth conditions, is discussed.
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Affiliation(s)
- Jesper T Pedersen
- Center for Membrane Pumps in Cells and Disease, Danish National Research Foundation, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Michael Palmgren
- Center for Membrane Pumps in Cells and Disease, Danish National Research Foundation, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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30
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Han M, Kopec W, Solov’yov IA, Khandelia H. Glutamate Water Gates in the Ion Binding Pocket of Na + Bound Na +, K +-ATPase. Sci Rep 2017; 7:39829. [PMID: 28084301 PMCID: PMC5233988 DOI: 10.1038/srep39829] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/25/2016] [Indexed: 11/15/2022] Open
Abstract
The dynamically changing protonation states of the six acidic amino acid residues in the ion binding pocket of the Na+, K+ -ATPase (NKA) during the ion transport cycle are proposed to drive ion binding, release and possibly determine Na+ or K+ selectivity. We use molecular dynamics (MD) and density functional theory (DFT) simulations to determine the protonation scheme of the Na+ bound conformation of NKA. MD simulations of all possible protonation schemes show that the bound Na+ ions are most stably bound when three or four protons reside in the binding sites, and that Glu954 in site III is always protonated. Glutamic acid residues in the three binding sites act as water gates, and their deprotonation triggers water entry to the binding sites. From DFT calculations of Na+ binding energies, we conclude that three protons in the binding site are needed to effectively bind Na+ from water and four are needed to release them in the next step. Protonation of Asp926 in site III will induce Na+ release, and Glu327, Glu954 and Glu779 are all likely to be protonated in the Na+ bound occluded conformation. Our data provides key insights into the role of protons in the Na+ binding and release mechanism of NKA.
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Affiliation(s)
- Minwoo Han
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Wojciech Kopec
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Ilia A. Solov’yov
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Himanshu Khandelia
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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31
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The Inner Workings of Proton Slippage through the Sodium Pump. Biophys J 2016; 111:2342-2344. [PMID: 27926835 DOI: 10.1016/j.bpj.2016.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 11/21/2022] Open
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32
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Abstract
The recently available genomic sequencing techniques have led to breakthroughs in understanding of the underlying genetic mechanisms in adrenocortical tumours. Disease-causing mutations have been described for aldosterone-producing adenomas, cortisol-producing adenomas and adrenocortical carcinomas. Further, knowledge gained from transcriptome analyses and methylation arrays has provided new insights into the development of these tumours. Elucidation of the genomic landscape of adrenocortical tumours and improved techniques may in the future be useful for early diagnosis through the detection of mutated DNA in the circulation. Moreover, compounds that bind specifically to altered proteins may be used as screening targets or therapeutic agents. Regulation of cortisol release by interaction with an altered subunit in adenylate cyclase may be more complex, but may provide a new option for regulating steroid release. Information about derangements in adrenocortical carcinoma is already helpful for determining patient prognosis. With further knowledge, we may be able to identify novel biomarkers that effectively and noninvasively help in differentiating between benign and malignant disease. It is clear that the next few years will provide much novel information that hopefully will aid in the treatment of patients with adrenocortical tumours.
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Affiliation(s)
- T Åkerström
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - T Carling
- Endocrine Research Unit, Yale University, New Haven, CT, USA
| | - F Beuschlein
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany
| | - P Hellman
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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33
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Lu FM, Deisl C, Hilgemann DW. Profound regulation of Na/K pump activity by transient elevations of cytoplasmic calcium in murine cardiac myocytes. eLife 2016; 5. [PMID: 27627745 PMCID: PMC5050017 DOI: 10.7554/elife.19267] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/09/2016] [Indexed: 01/06/2023] Open
Abstract
Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activation of Ca influx by reverse Na/Ca exchange enhances pump currents and attenuates current decay, while repeated Ca elevations suppress pump currents. Pump current enhancement reverses over 3 min, and results are similar in myocytes lacking the regulatory protein, phospholemman. Classical signaling mechanisms, including Ca-activated protein kinases and reactive oxygen, are evidently not involved. Electrogenic signals mediated by intramembrane movement of hydrophobic ions, such as hexyltriphenylphosphonium (C6TPP), increase and decrease in parallel with pump currents. Thus, transient Ca elevation and Na/K pump inactivation cause opposing sarcolemma changes that may affect diverse membrane processes.
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Affiliation(s)
- Fang-Min Lu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
| | - Christine Deisl
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
| | - Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, United States
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34
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Holm R, Toustrup-Jensen MS, Einholm AP, Schack VR, Andersen JP, Vilsen B. Neurological disease mutations of α3 Na +,K +-ATPase: Structural and functional perspectives and rescue of compromised function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1807-1828. [PMID: 27577505 DOI: 10.1016/j.bbabio.2016.08.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 08/19/2016] [Accepted: 08/25/2016] [Indexed: 11/26/2022]
Abstract
Na+,K+-ATPase creates transmembrane ion gradients crucial to the function of the central nervous system. The α-subunit of Na+,K+-ATPase exists as four isoforms (α1-α4). Several neurological phenotypes derive from α3 mutations. The effects of some of these mutations on Na+,K+-ATPase function have been studied in vitro. Here we discuss the α3 disease mutations as well as information derived from studies of corresponding mutations of α1 in the light of the high-resolution crystal structures of the Na+,K+-ATPase. A high proportion of the α3 disease mutations occur in the transmembrane sector and nearby regions essential to Na+ and K+ binding. In several cases the compromised function can be traced to disturbance of the Na+ specific binding site III. Recently, a secondary mutation was found to rescue the defective Na+ binding caused by a disease mutation. A perspective is that it may be possible to develop an efficient pharmaceutical mimicking the rescuing effect.
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Affiliation(s)
- Rikke Holm
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | | | - Anja P Einholm
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | - Vivien R Schack
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | - Jens P Andersen
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark.
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35
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Friedrich T, Tavraz NN, Junghans C. ATP1A2 Mutations in Migraine: Seeing through the Facets of an Ion Pump onto the Neurobiology of Disease. Front Physiol 2016; 7:239. [PMID: 27445835 PMCID: PMC4914835 DOI: 10.3389/fphys.2016.00239] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/03/2016] [Indexed: 12/31/2022] Open
Abstract
Mutations in four genes have been identified in familial hemiplegic migraine (FHM), from which CACNA1A (FHM type 1) and SCN1A (FHM type 3) code for neuronal voltage-gated calcium or sodium channels, respectively, while ATP1A2 (FHM type 2) encodes the α2 isoform of the Na(+),K(+)-ATPase's catalytic subunit, thus classifying FHM primarily as an ion channel/ion transporter pathology. FHM type 4 is attributed to mutations in the PRRT2 gene, which encodes a proline-rich transmembrane protein of as yet unknown function. The Na(+),K(+)-ATPase maintains the physiological gradients for Na(+) and K(+) ions and is, therefore, critical for the activity of ion channels and transporters involved neuronal excitability, neurotransmitter uptake or Ca(2+) signaling. Strikingly diverse functional abnormalities have been identified for disease-linked ATP1A2 mutations which frequently lead to changes in the enzyme's voltage-dependent properties, kinetics, or apparent cation affinities, but some mutations are truly deleterious for enzyme function and thus cause full haploinsufficiency. Here, we summarize structural and functional data about the Na(+),K(+)-ATPase available to date and an overview is provided about the particular properties of the α2 isoform that explain its physiological relevance in electrically excitable tissues. In addition, current concepts about the neurobiology of migraine, the correlations between primary brain dysfunction and mechanisms of headache pain generation are described, together with insights gained recently from modeling approaches in computational neuroscience. Then, a survey is given about ATP1A2 mutations implicated in migraine cases as documented in the literature with focus on mutations that were described to completely destroy enzyme function, or lead to misfolded or mistargeted protein in particular model cell lines. We also discuss whether or not there are correlations between these most severe mutational effects and clinical phenotypes. Finally, perspectives for future research on the implications of Na(+),K(+)-ATPase mutations in human pathologies are presented.
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Affiliation(s)
- Thomas Friedrich
- Department of Physical Chemistry/Bioenergetics, Institute of Chemistry, Technical University of BerlinBerlin, Germany
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36
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Cheng D, Feng M, Ji Y, Wu W, Hu Z. Effects of Celangulin IV and V From Celastrus angulatus Maxim on Na+/K+-ATPase Activities of the Oriental Armyworm (Lepidoptera: Noctuidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2016; 16:iew051. [PMID: 27324586 PMCID: PMC4913500 DOI: 10.1093/jisesa/iew051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/26/2016] [Indexed: 05/27/2023]
Abstract
Na(+)/K(+)-ATPase (sodium pump) is an important target for the development of botanical pesticide as it is responsible for transforming chemical energy in ATP to osmotic work and maintaining electrochemical Na(+ )and K(+ )gradients across the cell membrane of most animal cells. Celangulin IV (C-IV) and V (C-V), which are isolated from the root bark of Celastrus angulatus, are the major active ingredients of this insecticidal plant. The activities of C-IV and C-V on Na(+)/K(+)-ATPase were investigated by ultramicro measuring method to evaluate the effects of C-IV and C-V on Na(+)/K(+)-ATPase activities of the brain from the fifth Mythimna separata larvae and to discuss the insecticidal mechanism of C-IV and C-V. Results indicate that inhibitory activities of Na(+)/K(+)-ATPase by C-IV and C-V possess an obvious concentration-dependent in vitro. Compared with C-IV, the inhibition of C-V on Na(+)/K(+)-ATPase was not striking. In vivo, at a concentration of 25 mg/liter, the inhibition ratio of C-IV on Na(+)/K(+)-ATPase activity from the brain in narcosis and recovery period was more remarkable than that of C-V. Furthermore, the insects were fed with different mixture ratios of C-IV and C-V. The inhibition extent of Na(+)/K(+)-ATPase activity was corresponded with the dose of C-IV. However, C-V had no notable effects. This finding may mean that the mechanism of action of C-IV and C-V on Na(+)/K(+)-ATPase were different. Na(+)/K -ATPase may be an action target of C-IV and C-V.
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Affiliation(s)
- Dan Cheng
- College of Plant Protection, Institute of Pesticide Science, Northwest A&F University, Yangling, Shaanxi 712100, China (; ; ; ; ) Key Laboratory of Botanical Pesticide R & D in Shaanxi Province, Yangling, Shaanxi 712100, China
| | - Mingxing Feng
- College of Plant Protection, Institute of Pesticide Science, Northwest A&F University, Yangling, Shaanxi 712100, China (; ; ; ; ) Key Laboratory of Botanical Pesticide R & D in Shaanxi Province, Yangling, Shaanxi 712100, China
| | - Yufei Ji
- College of Plant Protection, Institute of Pesticide Science, Northwest A&F University, Yangling, Shaanxi 712100, China (; ; ; ; ) Key Laboratory of Botanical Pesticide R & D in Shaanxi Province, Yangling, Shaanxi 712100, China
| | - Wenjun Wu
- College of Plant Protection, Institute of Pesticide Science, Northwest A&F University, Yangling, Shaanxi 712100, China (; ; ; ; ) Key Laboratory of Botanical Pesticide R & D in Shaanxi Province, Yangling, Shaanxi 712100, China
| | - Zhaonong Hu
- College of Plant Protection, Institute of Pesticide Science, Northwest A&F University, Yangling, Shaanxi 712100, China (; ; ; ; ) Key Laboratory of Botanical Pesticide R & D in Shaanxi Province, Yangling, Shaanxi 712100, China
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Holm TH, Lykke-Hartmann K. Insights into the Pathology of the α3 Na(+)/K(+)-ATPase Ion Pump in Neurological Disorders; Lessons from Animal Models. Front Physiol 2016; 7:209. [PMID: 27378932 PMCID: PMC4906016 DOI: 10.3389/fphys.2016.00209] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 05/22/2016] [Indexed: 01/08/2023] Open
Abstract
The transmembrane Na(+)-/K(+) ATPase is located at the plasma membrane of all mammalian cells. The Na(+)-/K(+) ATPase utilizes energy from ATP hydrolysis to extrude three Na(+) cations and import two K(+) cations into the cell. The minimum constellation for an active Na(+)-/K(+) ATPase is one alpha (α) and one beta (β) subunit. Mammals express four α isoforms (α1-4), encoded by the ATP1A1-4 genes, respectively. The α1 isoform is ubiquitously expressed in the adult central nervous system (CNS) whereas α2 primarily is expressed in astrocytes and α3 in neurons. Na(+) and K(+) are the principal ions involved in action potential propagation during neuronal depolarization. The α1 and α3 Na(+)-/K(+) ATPases are therefore prime candidates for restoring neuronal membrane potential after depolarization and for maintaining neuronal excitability. The α3 isoform has approximately four-fold lower Na(+) affinity compared to α1 and is specifically required for rapid restoration of large transient increases in [Na(+)]i. Conditions associated with α3 deficiency are therefore likely aggravated by suprathreshold neuronal activity. The α3 isoform been suggested to support re-uptake of neurotransmitters. These processes are required for normal brain activity, and in fact autosomal dominant de novo mutations in ATP1A3 encoding the α3 isoform has been found to cause the three neurological diseases Rapid Onset Dystonia Parkinsonism (RDP), Alternating Hemiplegia of Childhood (AHC), and Cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS). All three diseases cause acute onset of neurological symptoms, but the predominant neurological manifestations differ with particularly early onset of hemiplegic/dystonic episodes and mental decline in AHC, ataxic encephalopathy and impairment of vision and hearing in CAPOS syndrome and late onset of dystonia/parkinsonism in RDP. Several mouse models have been generated to study the in vivo consequences of Atp1a3 modulation. The different mice show varying degrees of hyperactivity, gait problems, and learning disability as well as stress-induced seizures. With the advent of several Atp1a3-gene or chemically modified animal models that closely phenocopy many aspects of the human disorders, we will be able to reach a much better understanding of the etiology of RDP, AHC, and CAPOS syndrome.
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Affiliation(s)
- Thomas H. Holm
- Department of Biomedicine, Aarhus UniversityAarhus, Denmark
- Department of Molecular Biology and Genetics, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Aarhus UniversityAarhus, Denmark
| | - Karin Lykke-Hartmann
- Department of Biomedicine, Aarhus UniversityAarhus, Denmark
- Department of Molecular Biology and Genetics, Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Aarhus UniversityAarhus, Denmark
- Aarhus Institute of Advanced Studies, Aarhus UniversityAarhus, Denmark
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Durlacher CT, Chow K, Chen XW, He ZX, Zhang X, Yang T, Zhou SF. Targeting Na⁺/K⁺ -translocating adenosine triphosphatase in cancer treatment. Clin Exp Pharmacol Physiol 2016; 42:427-43. [PMID: 25739707 DOI: 10.1111/1440-1681.12385] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/09/2015] [Accepted: 02/21/2015] [Indexed: 12/24/2022]
Abstract
The Na(+) /K(+) -translocating adenosine triphosphatase (ATPase) transports sodium and potassium across the plasma membrane and represents a potential target in cancer chemotherapy. Na(+) /K(+) -ATPase belongs to the P-type ATPase family (also known as E1-E2 ATPase), which is involved in transporting certain ions, metals, and lipids across the plasma membrane of mammalian cells. In humans, the Na(+) /K(+) -ATPase is a binary complex of an α-subunit that has four isoforms (α1 -α4 ) and a β-subunit that has three isoforms (β1 -β3 ). This review aims to update our knowledge on the role of Na(+) /K(+) -ATPase in cancer development and metastasis, as well as on how Na(+) /K(+) -ATPase inhibitors kill tumour cells. The Na(+) /K(+) -ATPase has been found to be associated with cancer initiation, growth, development, and metastasis. Cardiac glycosides have exhibited anticancer effects in cell-based and mouse studies via inhibition of the Na(+) /K(+) -ATPase and other mechanisms. Na(+) /K(+) -ATPase inhibitors may kill cancer cells via induction of apoptosis and autophagy, radical oxygen species production, and cell cycle arrest. They also modulate multiple signalling pathways that regulate cancer cell survival and death, which contributes to their antiproliferative activities in cancer cells. The clinical evidence supporting the use of Na(+) /K(+) -ATPase inhibitors as anticancer drugs is weak. Several phase I and phase II clinical trials with digoxin, Anvirzel, and huachansu (an intravenous formulated extract of the venom of the wild toad), either alone or more often in combination with other anticancer agents, have shown acceptable safety profiles but limited efficacy in cancer patients. Well-designed randomized clinical trials with reasonable sample sizes are certainly warranted to confirm the efficacy and safety of cardiac glycosides for the treatment of cancer.
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Affiliation(s)
- Cameron T Durlacher
- Department of Pharmaceutical Science, College of Pharmacy, University of South Florida, Tampa, FL, USA
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Åkerström T, Maharjan R, Sven Willenberg H, Cupisti K, Ip J, Moser A, Stålberg P, Robinson B, Alexander Iwen K, Dralle H, Walz MK, Lehnert H, Sidhu S, Gomez-Sanchez C, Hellman P, Björklund P. Activating mutations in CTNNB1 in aldosterone producing adenomas. Sci Rep 2016; 6:19546. [PMID: 26815163 PMCID: PMC4728393 DOI: 10.1038/srep19546] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/12/2015] [Indexed: 12/11/2022] Open
Abstract
Primary aldosteronism (PA) is the most common cause of secondary hypertension with a prevalence of 5–10% in unreferred hypertensive patients. Aldosterone producing adenomas (APAs) constitute a large proportion of PA cases and represent a surgically correctable form of the disease. The WNT signaling pathway is activated in APAs. In other tumors, a frequent cause of aberrant WNT signaling is mutation in the CTNNB1 gene coding for β-catenin. Our objective was to screen for CTNNB1 mutations in a well-characterized cohort of 198 APAs. Somatic CTNNB1 mutations were detected in 5.1% of the tumors, occurring mutually exclusive from mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D. All of the observed mutations altered serine/threonine residues in the GSK3β binding domain in exon 3. The mutations were associated with stabilized β-catenin and increased AXIN2 expression, suggesting activation of WNT signaling. By CYP11B2 mRNA expression, CYP11B2 protein expression, and direct measurement of aldosterone in tumor tissue, we confirmed the ability for aldosterone production. This report provides compelling evidence that aberrant WNT signaling caused by mutations in CTNNB1 occur in APAs. This also suggests that other mechanisms that constitutively activate the WNT pathway may be important in APA formation.
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Affiliation(s)
- Tobias Åkerström
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Rajani Maharjan
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Kenko Cupisti
- General, Visceral and Pediatric Surgery University Hospital Düsseldorf, Düsseldorf, Germany
| | - Julian Ip
- University of Sydney, Endocrine Surgical Unit and Cancer Genetics, Hormones and Cancer Group, Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, Australia
| | - Ana Moser
- Department of Medicine I, University of Lübeck, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Peter Stålberg
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Bruce Robinson
- University of Sydney, Endocrine Surgical Unit and Cancer Genetics, Hormones and Cancer Group, Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, Australia
| | - K Alexander Iwen
- Department of Medicine I, University of Lübeck, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Henning Dralle
- Department of General, Visceral and Vascular Surgery, University Hospital, University of Halle-Wittenberg, Halle/Saale, Germany. Sweden
| | - Martin K Walz
- Klinik für Chirurgie und Zentrum für Minimal Invasive Chirurgie, Kliniken Essen-Mitte, Essen, Germany
| | - Hendrik Lehnert
- Department of Medicine I, University of Lübeck, University Hospital Schleswig-Holstein, Lübeck, Germany
| | - Stan Sidhu
- University of Sydney, Endocrine Surgical Unit and Cancer Genetics, Hormones and Cancer Group, Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, Australia
| | - Celso Gomez-Sanchez
- Endocrine Section, Department of Medicine, G.V. (Sonny) Montgomery VA Medical Center and University of Mississippi Medical Center, Jackson, USA
| | - Per Hellman
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Peyman Björklund
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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Clausen MV, Nissen P, Poulsen H. The α4 isoform of the Na⁺,K⁺-ATPase is tuned for changing extracellular environments. FEBS J 2015; 283:282-93. [PMID: 26476261 DOI: 10.1111/febs.13567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 09/20/2015] [Accepted: 10/15/2015] [Indexed: 11/30/2022]
Abstract
In their journey from the male to the female reproductive tract, spermatozoa are confronted with a constantly changing environment. To cope with the associated challenges, spermatozoa express a distinct set of transporters, channels and pumps. One of the membrane proteins unique to spermatozoa is the α4 isoform of the Na(+) ,K(+) -ATPase. In addition to α4, spermatozoa express the ubiquous α1 variant. To get a detailed understanding of how α1 and α4 differ, and why spermatozoa need an additional Na(+) ,K(+) -ATPase, we have conducted an electrophysiological comparison of the rodent isoforms (rat α4 versus mouse α1-3) using the Xenopus oocyte expression system. We demonstrate isoform-specific differences in the voltage sensitivity of steady-state turnover, with α2 being the more sensitive, and α1 and α2 having faster Na(+) release kinetics than α3 and α4. Our data further show that the α1 and α2 turnover rates are fast compared with those of α3 and α4. Finally, α4 is less influenced by changes in extracellular Na(+) and temperature than α1. Based on these findings, we discuss the possibility that evolution has selected robust activity rather than rapid turnover for α4.
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Affiliation(s)
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
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41
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Kirshenbaum GS, Dachtler J, Roder JC, Clapcote SJ. Transgenic rescue of phenotypic deficits in a mouse model of alternating hemiplegia of childhood. Neurogenetics 2015; 17:57-63. [PMID: 26463346 PMCID: PMC4701769 DOI: 10.1007/s10048-015-0461-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 09/16/2015] [Indexed: 11/13/2022]
Abstract
Missense mutations in ATP1A3 encoding Na+,K+-ATPase α3 are the primary cause of alternating hemiplegia of childhood (AHC). Most ATP1A3 mutations in AHC lie within a cluster in or near transmembrane α-helix TM6, including I810N that is also found in the Myshkin mouse model of AHC. These mutations all substantially reduce Na+,K+-ATPase α3 activity. Herein, we show that Myshkin mice carrying a wild-type Atp1a3 transgene that confers a 16 % increase in brain-specific total Na+,K+-ATPase activity show significant phenotypic improvements compared with non-transgenic Myshkin mice. Interventions to increase the activity of wild-type Na+,K+-ATPase α3 in AHC patients should be investigated further.
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Affiliation(s)
- Greer S Kirshenbaum
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University Avenue, Toronto, ON, M5G 1X5, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - James Dachtler
- School of Biomedical Sciences, Garstang Building, University of Leeds, Leeds, LS2 9JT, UK
| | - John C Roder
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University Avenue, Toronto, ON, M5G 1X5, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Steven J Clapcote
- School of Biomedical Sciences, Garstang Building, University of Leeds, Leeds, LS2 9JT, UK.
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DiFranco M, Hakimjavadi H, Lingrel JB, Heiny JA. Na,K-ATPase α2 activity in mammalian skeletal muscle T-tubules is acutely stimulated by extracellular K+. ACTA ACUST UNITED AC 2015; 146:281-94. [PMID: 26371210 PMCID: PMC4586590 DOI: 10.1085/jgp.201511407] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 08/21/2015] [Indexed: 11/20/2022]
Abstract
The K+ affinity of the Na,K-ATPase α2 isoform matches its activity to the range of extracellular K+ concentrations in the T-tubules at rest and during contraction, maintaining the excitability of active muscle. The Na,K-ATPase α2 isoform is the predominant Na,K-ATPase in adult skeletal muscle and the sole Na,K-ATPase in the transverse tubules (T-tubules). In quiescent muscles, the α2 isozyme operates substantially below its maximal transport capacity. Unlike the α1 isoform, the α2 isoform is not required for maintaining resting ion gradients or the resting membrane potential, canonical roles of the Na,K-ATPase in most other cells. However, α2 activity is stimulated immediately upon the start of contraction and, in working muscles, its contribution is crucial to maintaining excitation and resisting fatigue. Here, we show that α2 activity is determined in part by the K+ concentration in the T-tubules, through its K+ substrate affinity. Apparent K+ affinity was determined from measurements of the K1/2 for K+ activation of pump current in intact, voltage-clamped mouse flexor digitorum brevis muscle fibers. Pump current generated by the α2 Na,K-ATPase, Ip, was identified as the outward current activated by K+ and inhibited by micromolar ouabain. Ip was outward at all potentials studied (−90 to −30 mV) and increased with depolarization in the subthreshold range, −90 to −50 mV. The Q10 was 2.1 over the range of 22–37°C. The K1/2,K of Ip was 4.3 ± 0.3 mM at −90 mV and was relatively voltage independent. This K+ affinity is lower than that reported for other cell types but closely matches the dynamic range of extracellular K+ concentrations in the T-tubules. During muscle contraction, T-tubule luminal K+ increases in proportion to the frequency and duration of action potential firing. This K1/2,K predicts a low fractional occupancy of K+ substrate sites at the resting extracellular K+ concentration, with occupancy increasing in proportion to the frequency of membrane excitation. The stimulation of preexisting pumps by greater K+ site occupancy thus provides a rapid mechanism for increasing α2 activity in working muscles.
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Affiliation(s)
- Marino DiFranco
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hesamedin Hakimjavadi
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Jerry B Lingrel
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
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Tashkin VY, Gavrilchik AN, Ilovaisky AI, Apell HJ, Sokolov VS. Electrogenic binding of ions at the cytoplasmic side of the Na+,K+-ATPase. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2015. [DOI: 10.1134/s1990747815020105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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44
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Regulation of cough by neuronal Na(+)-K(+) ATPases. Curr Opin Pharmacol 2015; 22:140-5. [PMID: 26048736 DOI: 10.1016/j.coph.2015.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/29/2015] [Accepted: 05/01/2015] [Indexed: 01/10/2023]
Abstract
The Na(+)-K(+) ATPases play an essential role in establishing the sodium gradients in excitable cells. Multiple isoforms of the sodium pumps have been identified, with tissue and cell specific expression patterns. Because the vagal afferent nerves regulating cough must be activated at sustained high frequencies of action potential patterning to achieve cough initiation thresholds, it is a certainty that sodium pump function is essential to maintaining cough reflex sensitivities in health and in disease. The mechanisms by which Na(+)-K(+) ATPases regulate bronchopulmonary vagal afferent nerve excitability are reviewed as are potential therapeutic strategies targeting the sodium pumps in cough.
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45
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Viollet L, Glusman G, Murphy KJ, Newcomb TM, Reyna SP, Sweney M, Nelson B, Andermann F, Andermann E, Acsadi G, Barbano RL, Brown C, Brunkow ME, Chugani HT, Cheyette SR, Collins A, DeBrosse SD, Galas D, Friedman J, Hood L, Huff C, Jorde LB, King MD, LaSalle B, Leventer RJ, Lewelt AJ, Massart MB, Mérida MR, Ptáček LJ, Roach JC, Rust RS, Renault F, Sanger TD, Sotero de Menezes MA, Tennyson R, Uldall P, Zhang Y, Zupanc M, Xin W, Silver K, Swoboda KJ. Alternating Hemiplegia of Childhood: Retrospective Genetic Study and Genotype-Phenotype Correlations in 187 Subjects from the US AHCF Registry. PLoS One 2015; 10:e0127045. [PMID: 25996915 PMCID: PMC4440742 DOI: 10.1371/journal.pone.0127045] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 04/11/2015] [Indexed: 11/21/2022] Open
Abstract
Mutations in ATP1A3 cause Alternating Hemiplegia of Childhood (AHC) by disrupting function of the neuronal Na+/K+ ATPase. Published studies to date indicate 2 recurrent mutations, D801N and E815K, and a more severe phenotype in the E815K cohort. We performed mutation analysis and retrospective genotype-phenotype correlations in all eligible patients with AHC enrolled in the US AHC Foundation registry from 1997-2012. Clinical data were abstracted from standardized caregivers’ questionnaires and medical records and confirmed by expert clinicians. We identified ATP1A3 mutations by Sanger and whole genome sequencing, and compared phenotypes within and between 4 groups of subjects, those with D801N, E815K, other ATP1A3 or no ATP1A3 mutations. We identified heterozygous ATP1A3 mutations in 154 of 187 (82%) AHC patients. Of 34 unique mutations, 31 (91%) are missense, and 16 (47%) had not been previously reported. Concordant with prior studies, more than 2/3 of all mutations are clustered in exons 17 and 18. Of 143 simplex occurrences, 58 had D801N (40%), 38 had E815K (26%) and 11 had G937R (8%) mutations. Patients with an E815K mutation demonstrate an earlier age of onset, more severe motor impairment and a higher prevalence of status epilepticus. This study further expands the number and spectrum of ATP1A3 mutations associated with AHC and confirms a more deleterious effect of the E815K mutation on selected neurologic outcomes. However, the complexity of the disorder and the extensive phenotypic variability among subgroups merits caution and emphasizes the need for further studies.
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Affiliation(s)
- Louis Viollet
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Gustavo Glusman
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Kelley J. Murphy
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Tara M. Newcomb
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Sandra P. Reyna
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Matthew Sweney
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Benjamin Nelson
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Frederick Andermann
- Neurogenetics Unit, Montreal Neurologic Institute and Hospital, McGill University, Montreal Quebec, Canada
| | - Eva Andermann
- Neurogenetics Unit, Montreal Neurologic Institute and Hospital, McGill University, Montreal Quebec, Canada
| | - Gyula Acsadi
- Departments of Pediatrics and Neurology, Connecticut Children's Medical Center and University of Connecticut School of Medicine, Hartford, CT, United States of America
| | - Richard L. Barbano
- Department of Neurology, University of Rochester School of Medicine, Rochester, New York, United States of America
| | - Candida Brown
- Diablo Valley Child Neurology, an affiliate of Stanford Health Alliance, Pleasant Hill, California, United States of America
| | - Mary E. Brunkow
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Harry T. Chugani
- Division of Pediatric Neurology, Children's Hospital of Michigan, Wayne State University, Detroit, Michigan, United States of America
| | - Sarah R. Cheyette
- Department of Child Neurology, Palo Alto Medical Foundation Redwood City Clinic, Redwood City, California, United States of America
| | - Abigail Collins
- Department of Pediatric Neurology, Children’s Hospital Colorado, University of Colorado Hospital, Aurora, Colorado, United States of America
| | - Suzanne D. DeBrosse
- Departments of Genetics and Genome Sciences, Pediatrics, and Neurology, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio, United States of America
| | - David Galas
- Pacific Northwest Diabetes Research Institute, Seattle, Washington, United States of America
| | - Jennifer Friedman
- Departments of Neuroscience and Pediatrics, University of California San Diego, San Diego, California, United States of America
| | - Lee Hood
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Chad Huff
- Department of Epidemiology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Lynn B. Jorde
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, United States of America
| | - Mary D. King
- Departments of Pediatrics and Neurology, University College Dublin School of Medicine and Medical Science, Dublin, Ireland
| | - Bernie LaSalle
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Richard J. Leventer
- Children’s Neuroscience Centre, Murdoch Childrens Research Institute, University of Melbourne Department of Paediatrics, The Royal Children’s Hospital Melbourne, Parkville Victoria, Australia
| | - Aga J. Lewelt
- Department of Pediatrics, College of Medicine Jacksonville, University of Florida, Jacksonville, Florida, United States of America
| | - Mylynda B. Massart
- Department of Family Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Mario R. Mérida
- Stevens Henager College, Salt Lake City, Utah, United States of America
| | - Louis J. Ptáček
- Department of Neurology, University of California San Francisco, San Francisco, California, United States of America
| | - Jared C. Roach
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Robert S. Rust
- Center for Medical Ethics and Humanities in Medicine, University Of Virginia UVA health system, Charlottesville, Virginia, United States of America
| | - Francis Renault
- Departement de Neurophysiologie. Hopital Armand Trousseau APHP, Paris, France
| | - Terry D. Sanger
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, United States of America
| | | | - Rachel Tennyson
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
| | - Peter Uldall
- Department of Paediatrics and Adolescent Medicine, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Yue Zhang
- Study Design and Biostatistics Center, University of Utah, Salt Lake City, Utah, United States of America
| | - Mary Zupanc
- Department of Neurology, Children’s Hospital Orange County, and Department of Pediatrics, University of California, Orange, California, United States of America
| | - Winnie Xin
- Center for Human Genetic Research, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Kenneth Silver
- Departments of Pediatrics and Neurology, University of Chicago and Comer Children's Hospital, Chicago, Illinois, United States of America
| | - Kathryn J. Swoboda
- Pediatric Motor Disorders Research Program, Departments of Neurology and Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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46
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Holm R, Einholm AP, Andersen JP, Vilsen B. Rescue of Na+ affinity in aspartate 928 mutants of Na+,K+-ATPase by secondary mutation of glutamate 314. J Biol Chem 2015; 290:9801-11. [PMID: 25713066 DOI: 10.1074/jbc.m114.625509] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Indexed: 11/06/2022] Open
Abstract
The Na(+),K(+)-ATPase binds Na(+) at three transport sites denoted I, II, and III, of which site III is Na(+)-specific and suggested to be the first occupied in the cooperative binding process activating phosphorylation from ATP. Here we demonstrate that the asparagine substitution of the aspartate associated with site III found in patients with rapid-onset dystonia parkinsonism or alternating hemiplegia of childhood causes a dramatic reduction of Na(+) affinity in the α1-, α2-, and α3-isoforms of Na(+),K(+)-ATPase, whereas other substitutions of this aspartate are much less disruptive. This is likely due to interference by the amide function of the asparagine side chain with Na(+)-coordinating residues in site III. Remarkably, the Na(+) affinity of site III aspartate to asparagine and alanine mutants is rescued by second-site mutation of a glutamate in the extracellular part of the fourth transmembrane helix, distant to site III. This gain-of-function mutation works without recovery of the lost cooperativity and selectivity of Na(+) binding and does not affect the E1-E2 conformational equilibrium or the maximum phosphorylation rate. Hence, the rescue of Na(+) affinity is likely intrinsic to the Na(+) binding pocket, and the underlying mechanism could be a tightening of Na(+) binding at Na(+) site II, possibly via movement of transmembrane helix four. The second-site mutation also improves Na(+),K(+) pump function in intact cells. Rescue of Na(+) affinity and Na(+) and K(+) transport by second-site mutation is unique in the history of Na(+),K(+)-ATPase and points to new possibilities for treatment of neurological patients carrying Na(+),K(+)-ATPase mutations.
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Affiliation(s)
- Rikke Holm
- From the Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
| | - Anja P Einholm
- From the Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
| | - Jens P Andersen
- From the Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
| | - Bente Vilsen
- From the Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
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Mitchell TJ, Zugarramurdi C, Olivera JF, Gatto C, Artigas P. Sodium and proton effects on inward proton transport through Na/K pumps. Biophys J 2015; 106:2555-65. [PMID: 24940773 DOI: 10.1016/j.bpj.2014.04.053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/12/2014] [Accepted: 04/23/2014] [Indexed: 11/29/2022] Open
Abstract
The Na/K pump hydrolyzes ATP to export three intracellular Na (Nai) as it imports two extracellular K (Ko) across animal plasma membranes. Within the protein, two ion-binding sites (sites I and II) can reciprocally bind Na or K, but a third site (site III) exclusively binds Na in a voltage-dependent fashion. In the absence of Nao and Ko, the pump passively imports protons, generating an inward current (IH). To elucidate the mechanisms of IH, we used voltage-clamp techniques to investigate the [H]o, [Na]o, and voltage dependence of IH in Na/K pumps from ventricular myocytes and in ouabain-resistant pumps expressed in Xenopus oocytes. Lowering pHo revealed that Ho both activates IH (in a voltage-dependent manner) and inhibits it (in a voltage-independent manner) by binding to different sites. Nao effects depend on pHo; at pHo where no Ho inhibition is observed, Nao inhibits IH at all concentrations, but when applied at pHo that inhibits pump-mediated current, low [Na]o activates IH and high [Na]o inhibits it. Our results demonstrate that IH is a property inherent to Na/K pumps, not linked to the oocyte expression environment, explains differences in the characteristics of IH previously reported in the literature, and supports a model in which 1), protons leak through site III; 2), binding of two Na or two protons to sites I and II inhibits proton transport; and 3), pumps with mixed Na/proton occupancy of sites I and II remain permeable to protons.
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Affiliation(s)
- Travis J Mitchell
- Department of Cell and Molecular Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas; School of Biological Sciences. Illinois State University, Normal, Illinois
| | - Camila Zugarramurdi
- Department of Cell and Molecular Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - J Fernando Olivera
- Department of Cell and Molecular Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Craig Gatto
- School of Biological Sciences. Illinois State University, Normal, Illinois
| | - Pablo Artigas
- Department of Cell and Molecular Physiology, Texas Tech University Health Sciences Center, Lubbock, Texas.
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A functional correlate of severity in alternating hemiplegia of childhood. Neurobiol Dis 2015; 77:88-93. [PMID: 25681536 DOI: 10.1016/j.nbd.2015.02.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 01/19/2015] [Accepted: 02/04/2015] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Mutations in ATP1A3, the gene that encodes the α3 subunit of the Na(+)/K(+) ATPase, are the primary cause of alternating hemiplegia of childhood (AHC). Correlations between different mutations and AHC severity were recently reported, with E815K identified in severe and D801N and G947R in milder cases. This study aims to explore the molecular pathological mechanisms in AHC and to identify functional correlates for mutations associated with different levels of disease severity. METHODS Human wild type ATP1A3, and E815K, D801N and G947R mutants were expressed in Xenopus laevis oocytes and Na(+)/K(+) ATPase function measured. Structural homology models of the human α3 subunit containing AHC mutations were created. RESULTS The AHC mutations examined all showed similar levels of reduction in forward cycling. Wild type forward cycling was reduced by coexpression with any mutant, indicating dominant negative interactions. Proton transport was measured and found to be selectively impaired only in E815K. Homology modeling showed that D801 and G947 lie within or near known cation binding sites while E815 is more distal. Despite its effect on proton transport, E815K was also distant from the proposed proton transport route. INTERPRETATION Loss of forward cycling and dominant negativity are common and likely necessary pathomechanisms for AHC. In addition, loss of proton transport correlated with severity of AHC. D801N and G947R are likely to directly disrupt normal Na(+)/K(+) binding while E815K may disrupt forward cycling and proton transport via allosteric mechanisms yet to be elucidated.
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Kao L, Azimov R, Abuladze N, Newman D, Kurtz I. Human SLC4A11-C functions as a DIDS-stimulatable H⁺(OH⁻) permeation pathway: partial correction of R109H mutant transport. Am J Physiol Cell Physiol 2014; 308:C176-88. [PMID: 25394471 DOI: 10.1152/ajpcell.00271.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The SLC4A11 gene mutations cause a variety of genetic corneal diseases, including congenital hereditary endothelial dystrophy 2 (CHED2), Harboyan syndrome, some cases of Fuchs' endothelial dystrophy (FECD), and possibly familial keratoconus. Three NH2-terminal variants of the human SLC4A11 gene, named SLC4A11-A, -B, and -C are known. The SLC4A11-B variant has been the focus of previous studies. Both the expression of the SLC4A11-C variant in the cornea and its functional properties have not been characterized, and therefore its potential pathophysiological role in corneal diseases remains to be explored. In the present study, we demonstrate that SLC4A11-C is the predominant SLC4A11 variant expressed in human corneal endothelial mRNA and that the transporter functions as an electrogenic H(+)(OH(-)) permeation pathway. Disulfonic stilbenes, including 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS), 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate (H2DIDS), and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonate (SITS), which are known to bind covalently, increased SLC4A11-C-mediated H(+)(OH(-)) flux by 150-200% without having a significant effect in mock-transfected cells. Noncovalently interacting 4,4'-diaminostilbene-2,2'-disulfonate (DADS) was without effect. We tested the efficacy of DIDS on the functionally impaired R109H mutant (SLC4A11-C numbering) that causes CHED2. DIDS (1 mM) increased H(+)(OH(-)) flux through the mutant transporter by ∼40-90%. These studies provide a basis for future testing of more specific chemically modified dilsulfonic stilbenes as potential therapeutic agents to improve the functional impairment of specific SLC4A11 mutant transporters.
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Affiliation(s)
- Liyo Kao
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Rustam Azimov
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Natalia Abuladze
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Debra Newman
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and
| | - Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; and Brain Research Institute, University of California Los Angeles, Los Angeles, California
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50
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Apell HJ. Does the sodium pump have secret levels? Biophys J 2014; 106:2552-4. [PMID: 24940772 DOI: 10.1016/j.bpj.2014.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 05/06/2014] [Indexed: 10/25/2022] Open
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