1
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Chu M, Wang Y, Mu B, Ge H, Zhang C, Zhao F, Fu A, Luan S, Li L, Lan W. An ICln homolog contributes to osmotic and low-nitrate tolerance by enhancing nitrate accumulation in Arabidopsis. PLANT, CELL & ENVIRONMENT 2021; 44:1580-1595. [PMID: 33495993 DOI: 10.1111/pce.14005] [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: 11/26/2019] [Revised: 01/06/2021] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Nitrate (NO3- ) is a source of plant nutrients and osmolytes, but its delivery machineries under osmotic and low-nutrient stress remain largely unknown. Here, we report that AtICln, an Arabidopsis homolog of the nucleotide-sensitive chloride-conductance regulatory protein family (ICln), is involved in response to osmotic and low-NO3- stress. The gene AtICln, encoding plasma membrane-anchored proteins, was upregulated by various osmotic stresses, and its disruption impaired plant tolerance to osmotic stress. Compared with the wild type, the aticln mutant retained lower anions, particularly NO3- , and its growth retardation was not rescued by NO3- supply under osmotic stress. Interestingly, this mutant also displayed growth defects under low-NO3 stress, which were accompanied by decreases in NO3- accumulation, suggesting that AtICln may facilitate the NO3- accumulation under NO3- deficiency. Moreover, the low-NO3- hypersensitive phenotype of aticln mutant was overridden by the overexpression of NRT1.1, an important NO3- transporter in Arabidopsis low-NO3- responses. Further genetic analysis in the plants with altered activity of AtICln and NRT1.1 indicated that AtICln and NRT1.1 play a compensatory role in maintaining NO3- homeostasis under low-NO3- environments. These results suggest that AtICln is involved in cellular NO3- accumulation and thus determines osmotic adjustment and low-NO3- tolerance in plants.
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Affiliation(s)
- Moli Chu
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yuan Wang
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xi'an, China
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - Baicong Mu
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Haiman Ge
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Chi Zhang
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Fugeng Zhao
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Aigen Fu
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xi'an, China
| | - Sheng Luan
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | - Legong Li
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Wenzhi Lan
- State Key Laboratory for Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
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2
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Costa R, Remigante A, Civello DA, Bernardinelli E, Szabó Z, Morabito R, Marino A, Sarikas A, Patsch W, Paulmichl M, Janáky T, Miseta A, Nagy T, Dossena S. O-GlcNAcylation Suppresses the Ion Current IClswell by Preventing the Binding of the Protein ICln to α-Integrin. Front Cell Dev Biol 2020; 8:607080. [PMID: 33330510 PMCID: PMC7717961 DOI: 10.3389/fcell.2020.607080] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/23/2020] [Indexed: 12/30/2022] Open
Abstract
O-GlcNAcylation is a post-translational modification of proteins that controls a variety of cellular processes, is chronically elevated in diabetes mellitus, and may contribute to the progression of diabetic complications, including diabetic nephropathy. Our previous work showed that increases in the O-GlcNAcylation of cellular proteins impair the homeostatic reaction of the regulatory volume decrease (RVD) after cell swelling by an unknown mechanism. The activation of the swelling-induced chloride current IClswell is a key step in RVD, and ICln, a ubiquitous protein involved in the activation of IClswell, is O-GlcNAcylated. Here, we show that experimentally increased O-GlcNAcylation of cellular proteins inhibited the endogenous as well as the ICln-induced IClswell current and prevented RVD in a human renal cell line, while decreases in O-GlcNAcylation augmented the current magnitude. In parallel, increases or decreases in O-GlcNAcylation, respectively, weakened or stabilized the binding of ICln to the intracellular domain of α-integrin, a process that is essential for the activation of IClswell. Mutation of the putative YinOYang site at Ser67 rendered the ICln-induced IClswell current unresponsive to O-GlcNAc variations, and the ICln interaction with α-integrin insensitive to O-GlcNAcylation. In addition, exposure of cells to a hypotonic solution reduced the O-GlcNAcylation of cellular proteins. Together, these findings show that O-GlcNAcylation affects RVD by influencing IClswell and further indicate that hypotonicity may activate IClswell by reducing the O-GlcNAcylation of ICln at Ser67, therefore permitting its binding to α-integrin. We propose that disturbances in the regulation of cellular volume may contribute to disease in settings of chronically elevated O-GlcNAcylation, including diabetic nephropathy.
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Affiliation(s)
- Roberta Costa
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Alessia Remigante
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria.,Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Davide A Civello
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Zoltán Szabó
- Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Rossana Morabito
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Angela Marino
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Wolfgang Patsch
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Markus Paulmichl
- Department of Personalized Medicine, Humanomed, Klagenfurt, Austria
| | - Tamás Janáky
- Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Attila Miseta
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Nagy
- Department of Laboratory Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
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3
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Binding of the protein ICln to α-integrin contributes to the activation of ICl swell current. Sci Rep 2019; 9:12195. [PMID: 31434921 PMCID: PMC6704128 DOI: 10.1038/s41598-019-48496-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/06/2019] [Indexed: 12/13/2022] Open
Abstract
IClswell is the chloride current induced by cell swelling, and plays a fundamental role in several biological processes, including the regulatory volume decrease (RVD). ICln is a highly conserved, ubiquitously expressed and multifunctional protein involved in the activation of IClswell. In platelets, ICln binds to the intracellular domain of the integrin αIIb chain, however, whether the ICln/integrin interaction plays a role in RVD is not known. Here we show that a direct molecular interaction between ICln and the integrin α-chain is not restricted to platelets and involves highly conserved amino acid motifs. Integrin α recruits ICln to the plasma membrane, thereby facilitating the activation of IClswell during hypotonicity. Perturbation of the ICln/integrin interaction prevents the transposition of ICln towards the cell surface and, in parallel, impedes the activation of IClswell. We suggest that the ICln/integrin interaction interface may represent a new molecular target enabling specific IClswell suppression in pathological conditions when this current is deregulated or plays a detrimental role.
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4
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Russo A, Ranieri M, Di Mise A, Dossena S, Pellegrino T, Furia E, Nofziger C, Debellis L, Paulmichl M, Valenti G, Tamma G. Interleukin-13 increases pendrin abundance to the cell surface in bronchial NCI-H292 cells via Rho/actin signaling. Pflugers Arch 2017; 469:1163-1176. [PMID: 28378089 DOI: 10.1007/s00424-017-1970-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/20/2017] [Accepted: 03/22/2017] [Indexed: 11/28/2022]
Abstract
Interleukin-13 (IL13) is a major player in the development of airway hyperresponsiveness in several respiratory disorders. Emerging data suggest that an increased expression of pendrin in airway epithelia is associated with elevated airway hyperreactivity in asthma. Here, we investigate the effect of IL13 on pendrin localization and function using bronchiolar NCI-H292 cells. The data obtained revealed that IL13 increases the cell surface expression of pendrin. This effect was paralleled by a significant increase in the intracellular pH, possibly via indirect stimulation of NHE. IL13 effect on pendrin localization and intracellular pH was reversed by theophylline, a bronchodilator compound used to treat asthma. IL13 upregulated RhoA activity, a crucial protein controlling actin dynamics, via G-alpha-13. Specifically, IL13 stabilized actin cytoskeleton and promoted co-localization and a direct molecular interaction between pendrin and F-actin in the plasma membrane region. These effects were reversed following exposure of cells to theophylline. Selective inhibition of Rho kinase, a downstream effector of Rho, reduced the IL13-dependent cell surface expression of pendrin. Together, these data indicate that IL13 increases pendrin abundance to the cell surface via Rho/actin signaling, an effect reversed by theophylline.
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Affiliation(s)
- Annamaria Russo
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy.
| | - Annarita Di Mise
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Tommaso Pellegrino
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Emilia Furia
- Department of Chemistry and Chemical Technologies, University of Calabria, Rende, Italy
| | - Charity Nofziger
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Lucantonio Debellis
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Markus Paulmichl
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Giovanna Valenti
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy.,Istituto Nazionsale di Biostrutture e Biosistemi (I.N.B.B.), Rome, Italy.,Centre of Excellence Genomic and Proteomics GEBCA, University of Bari, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy. .,Istituto Nazionsale di Biostrutture e Biosistemi (I.N.B.B.), Rome, Italy.
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5
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Li B, Tester M, Gilliham M. Chloride on the Move. TRENDS IN PLANT SCIENCE 2017; 22:236-248. [PMID: 28081935 DOI: 10.1016/j.tplants.2016.12.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/21/2016] [Accepted: 12/11/2016] [Indexed: 05/20/2023]
Abstract
Chloride (Cl-) is an essential plant nutrient but under saline conditions it can accumulate to toxic levels in leaves; limiting this accumulation improves the salt tolerance of some crops. The rate-limiting step for this process - the transfer of Cl- from root symplast to xylem apoplast, which can antagonize delivery of the macronutrient nitrate (NO3-) to shoots - is regulated by abscisic acid (ABA) and is multigenic. Until recently the molecular mechanisms underpinning this salt-tolerance trait were poorly defined. We discuss here how recent advances highlight the role of newly identified transport proteins, some that directly transfer Cl- into the xylem, and others that act on endomembranes in 'gatekeeper' cell types in the root stele to control root-to-shoot delivery of Cl-.
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Affiliation(s)
- Bo Li
- King Abdullah University of Science and Technology (KAUST), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Mark Tester
- King Abdullah University of Science and Technology (KAUST), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Matthew Gilliham
- Plant Transport and Signalling Group, Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, SA 5064, Australia.
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6
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Ranieri M, Tamma G, Di Mise A, Russo A, Centrone M, Svelto M, Calamita G, Valenti G. Negative feedback from CaSR signaling to aquaporin-2 sensitizes vasopressin to extracellular Ca2. J Cell Sci 2015; 128:2350-60. [PMID: 25977473 DOI: 10.1242/jcs.168096] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/05/2015] [Indexed: 01/10/2023] Open
Abstract
We previously described that high luminal Ca(2+) in the renal collecting duct attenuates short-term vasopressin-induced aquaporin-2 (AQP2) trafficking through activation of the Ca(2+)-sensing receptor (CaSR). Here, we evaluated AQP2 phosphorylation and permeability, in both renal HEK-293 cells and in the dissected inner medullary collecting duct, in response to specific activation of CaSR with NPS-R568. In CaSR-transfected cells, CaSR activation drastically reduced the basal levels of AQP2 phosphorylation at S256 (AQP2-pS256), thus having an opposite effect to vasopressin action. When forskolin stimulation was performed in the presence of NPS-R568, the increase in AQP2-pS256 and in the osmotic water permeability were prevented. In the freshly isolated inner mouse medullar collecting duct, stimulation with forskolin in the presence of NPS-R568 prevented the increase in AQP2-pS256 and osmotic water permeability. Our data demonstrate that the activation of CaSR in the collecting duct prevents the cAMP-dependent increase in AQP2-pS256 and water permeability, counteracting the short-term vasopressin response. By extension, our results suggest the attractive concept that CaSR expressed in distinct nephron segments exerts a negative feedback on hormones acting through cAMP, conferring high sensitivity of hormone to extracellular Ca(2+).
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Affiliation(s)
- Marianna Ranieri
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy
| | - Grazia Tamma
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy Istituto Nazionale di Biostrutture e Biosistemi (I.N.B.B.) 00136, Rome, Italy
| | - Annarita Di Mise
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy
| | - Annamaria Russo
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy
| | - Mariangela Centrone
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy
| | - Maria Svelto
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy Istituto Nazionale di Biostrutture e Biosistemi (I.N.B.B.) 00136, Rome, Italy Centro di Eccellenza di Genomica in campo Biomedico ed Agrario (CEGBA) 70125, Bari, Italy
| | - Giuseppe Calamita
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy Istituto Nazionale di Biostrutture e Biosistemi (I.N.B.B.) 00136, Rome, Italy
| | - Giovanna Valenti
- Dept of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, 70125, Bari, Italy Istituto Nazionale di Biostrutture e Biosistemi (I.N.B.B.) 00136, Rome, Italy Centro di Eccellenza di Genomica in campo Biomedico ed Agrario (CEGBA) 70125, Bari, Italy
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7
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Wang Z, Zhang J, Ye M, Zhu M, Zhang B, Roy M, Liu J, An X. Tumor suppressor role of protein 4.1B/DAL-1. Cell Mol Life Sci 2014; 71:4815-30. [PMID: 25183197 PMCID: PMC11113756 DOI: 10.1007/s00018-014-1707-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/21/2014] [Accepted: 08/15/2014] [Indexed: 12/14/2022]
Abstract
Protein 4.1B/DAL-1 is a membrane skeletal protein that belongs to the protein 4.1 family. Protein 4.1B/DAL-1 is localized to sites of cell-cell contact and functions as an adapter protein, linking the plasma membrane to the cytoskeleton or associated cytoplasmic signaling effectors and facilitating their activities in various pathways. Protein 4.1B/DAL-1 is involved in various cytoskeleton-associated processes, such as cell motility and adhesion. Moreover, protein 4.1B/DAL-1 also plays a regulatory role in cell growth, differentiation, and the establishment of epithelial-like cell structures. Protein 4.1B/DAL-1 is normally expressed in multiple human tissues, but loss of its expression or prominent down-regulation of its expression is frequently observed in corresponding tumor tissues and tumor cell lines, suggesting that protein 4.1B/DAL-1 is involved in the molecular pathogenesis of these tumors and acts as a potential tumor suppressor. This review will focus on the structure of protein 4.1B/DAL-1, 4.1B/DAL-1-interacting molecules, 4.1B/DAL-1 inactivation and tumor progression, and anti-tumor activity of the 4.1B/DAL-1.
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Affiliation(s)
- Zi Wang
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Ji Zhang
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
- Department of Hematology, The First Affiliated Hospital, University of South China, Hengyang, 421001 China
| | - Mao Ye
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, 410082 China
| | - Min Zhu
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Bin Zhang
- Department of Histology and Embryology, Xiangya School Medicine, Central South University, Changsha, 410083 China
| | - Mridul Roy
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Jing Liu
- Molecular Biology Research Center, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, 410078 China
- State Key Laboratory of Medical Genetics, Central South University, 110 Xiangya Road, Changsha, 410078 China
| | - Xiuli An
- Laboratory of Membrane Biology, New York Blood Center, 310 E 67th Street, New York, 10065 USA
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8
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Bazzini C, Benedetti L, Civello D, Zanoni C, Rossetti V, Marchesi D, Garavaglia ML, Paulmichl M, Francolini M, Meyer G, Rodighiero S. ICln: a new regulator of non-erythroid 4.1R localisation and function. PLoS One 2014; 9:e108826. [PMID: 25295618 PMCID: PMC4189953 DOI: 10.1371/journal.pone.0108826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 08/27/2014] [Indexed: 01/12/2023] Open
Abstract
To optimise the efficiency of cell machinery, cells can use the same protein (often called a hub protein) to participate in different cell functions by simply changing its target molecules. There are large data sets describing protein-protein interactions (“interactome”) but they frequently fail to consider the functional significance of the interactions themselves. We studied the interaction between two potential hub proteins, ICln and 4.1R (in the form of its two splicing variants 4.1R80 and 4.1R135), which are involved in such crucial cell functions as proliferation, RNA processing, cytoskeleton organisation and volume regulation. The sub-cellular localisation and role of native and chimeric 4.1R over-expressed proteins in human embryonic kidney (HEK) 293 cells were examined. ICln interacts with both 4.1R80 and 4.1R135 and its over-expression displaces 4.1R from the membrane regions, thus affecting 4.1R interaction with ß-actin. It was found that 4.1R80 and 4.1R135 are differently involved in regulating the swelling activated anion current (ICl,swell) upon hypotonic shock, a condition under which both isoforms are dislocated from the membrane region and thus contribute to ICl,swell current regulation. Both 4.1R isoforms are also differently involved in regulating cell morphology, and ICln counteracts their effects. The findings of this study confirm that 4.1R plays a role in cell volume regulation and cell morphology and indicate that ICln is a new negative regulator of 4.1R functions.
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Affiliation(s)
- Claudia Bazzini
- Department of Biosciences, University of Milan, Milan, Italy
| | - Lorena Benedetti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
- Fondazione Filarete for Biosciences and Innovation, Milan, Italy
| | - Davide Civello
- Department of Biosciences, University of Milan, Milan, Italy
| | - Chiara Zanoni
- Pharmaceutical Sciences Department (DISFARM), University of Milan, Milan, Italy
| | | | - Davide Marchesi
- Fondazione Filarete for Biosciences and Innovation, Milan, Italy
| | | | - Markus Paulmichl
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Maura Francolini
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
- Fondazione Filarete for Biosciences and Innovation, Milan, Italy
| | - Giuliano Meyer
- Department of Biosciences, University of Milan, Milan, Italy
| | - Simona Rodighiero
- Fondazione Filarete for Biosciences and Innovation, Milan, Italy
- * E-mail:
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9
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Reddy A, Cho J, Ling S, Reddy V, Shlykov M, Saier MH. Reliability of nine programs of topological predictions and their application to integral membrane channel and carrier proteins. J Mol Microbiol Biotechnol 2014; 24:161-90. [PMID: 24992992 DOI: 10.1159/000363506] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We evaluated topological predictions for nine different programs, HMMTOP, TMHMM, SVMTOP, DAS, SOSUI, TOPCONS, PHOBIUS, MEMSAT-SVM (hereinafter referred to as MEMSAT), and SPOCTOPUS. These programs were first evaluated using four large topologically well-defined families of secondary transporters, and the three best programs were further evaluated using topologically more diverse families of channels and carriers. In the initial studies, the order of accuracy was: SPOCTOPUS > MEMSAT > HMMTOP > TOPCONS > PHOBIUS > TMHMM > SVMTOP > DAS > SOSUI. Some families, such as the Sugar Porter Family (2.A.1.1) of the Major Facilitator Superfamily (MFS; TC #2.A.1) and the Amino Acid/Polyamine/Organocation (APC) Family (TC #2.A.3), were correctly predicted with high accuracy while others, such as the Mitochondrial Carrier (MC) (TC #2.A.29) and the K(+) transporter (Trk) families (TC #2.A.38), were predicted with much lower accuracy. For small, topologically homogeneous families, SPOCTOPUS and MEMSAT were generally most reliable, while with large, more diverse superfamilies, HMMTOP often proved to have the greatest prediction accuracy. We next developed a novel program, TM-STATS, that tabulates HMMTOP, SPOCTOPUS or MEMSAT-based topological predictions for any subdivision (class, subclass, superfamily, family, subfamily, or any combination of these) of the Transporter Classification Database (TCDB; www.tcdb.org) and examined the following subclasses: α-type channel proteins (TC subclasses 1.A and 1.E), secreted pore-forming toxins (TC subclass 1.C) and secondary carriers (subclass 2.A). Histograms were generated for each of these subclasses, and the results were analyzed according to subclass, family and protein. The results provide an update of topological predictions for integral membrane transport proteins as well as guides for the development of more reliable topological prediction programs, taking family-specific characteristics into account.
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Affiliation(s)
- Abhinay Reddy
- Department of Molecular Biology, University of California at San Diego, La Jolla, Calif., USA
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10
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Tamma G, Lasorsa D, Trimpert C, Ranieri M, Di Mise A, Mola MG, Mastrofrancesco L, Devuyst O, Svelto M, Deen PMT, Valenti G. A protein kinase A-independent pathway controlling aquaporin 2 trafficking as a possible cause for the syndrome of inappropriate antidiuresis associated with polycystic kidney disease 1 haploinsufficiency. J Am Soc Nephrol 2014; 25:2241-53. [PMID: 24700872 DOI: 10.1681/asn.2013111234] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Renal water reabsorption is controlled by arginine vasopressin (AVP), which binds to V2 receptors, resulting in protein kinase A (PKA) activation, phosphorylation of aquaporin 2 (AQP2) at serine 256, and translocation of AQP2 to the plasma membrane. However, AVP also causes dephosphorylation of AQP2 at S261. Recent studies showed that cyclin-dependent kinases (cdks) can phosphorylate AQP2 peptides at S261 in vitro. We investigated the possible role of cdks in the phosphorylation of AQP2 and identified a new PKA-independent pathway regulating AQP2 trafficking. In ex vivo kidney slices and MDCK-AQP2 cells, R-roscovitine, a specific inhibitor of cdks, increased pS256 levels and decreased pS261 levels. The changes in AQP2 phosphorylation status were paralleled by increases in cell surface expression of AQP2 and osmotic water permeability in the absence of forskolin stimulation. R-Roscovitine did not alter cAMP-dependent PKA activity but specifically reduced protein phosphatase 2A (PP2A) expression and activity in MDCK cells. Notably, we found reduced PP2A expression and activity and reduced pS261 levels in Pkd1(+/-) mice displaying a syndrome of inappropriate antidiuresis with high levels of pS256, despite unchanged AVP and cAMP. Similar to previous findings in Pkd1(+/-) mice, R-roscovitine treatment caused a significant decrease in intracellular calcium in MDCK cells. Our data indicate that reduced activity of PP2A, secondary to reduced intracellular Ca(2+) levels, promotes AQP2 trafficking independent of the AVP-PKA axis. This pathway may be relevant for explaining pathologic states characterized by inappropriate AVP secretion and positive water balance.
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Affiliation(s)
- Grazia Tamma
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy;
| | - Domenica Lasorsa
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Christiane Trimpert
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands; and
| | - Marianna Ranieri
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Annarita Di Mise
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Maria Grazia Mola
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lisa Mastrofrancesco
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Olivier Devuyst
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Maria Svelto
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Peter M T Deen
- Department of Physiology, Radboud University Medical Centre, Nijmegen, The Netherlands; and
| | - Giovanna Valenti
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
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11
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Gutierrez-Uzquiza A, Colon-Gonzalez F, Leonard TA, Canagarajah BJ, Wang H, Mayer BJ, Hurley JH, Kazanietz MG. Coordinated activation of the Rac-GAP β2-chimaerin by an atypical proline-rich domain and diacylglycerol. Nat Commun 2013; 4:1849. [PMID: 23673634 PMCID: PMC3700536 DOI: 10.1038/ncomms2834] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/04/2013] [Indexed: 02/08/2023] Open
Abstract
Chimaerins, a family of GTPase activating proteins (GAPs) for the small G-protein Rac, have been implicated in development, neuritogenesis, and cancer. These Rac-GAPs are regulated by the lipid second messenger diacylglycerol (DAG) generated by tyrosine-kinases such as the epidermal growth factor receptor (EGFR). Here we identify an atypical Pro-rich motif in chimaerins that binds to the adaptor protein Nck1. Unlike most Nck1 partners, chimaerins bind to the third SH3 domain of Nck1. This association is mediated by electrostatic interactions of basic residues within the Pro-rich motif with acidic clusters in the SH3 domain. EGF promotes the binding of β2-chimaerin to Nck1 in the cell periphery in a DAG-dependent manner. Moreover, β2-chimaerin translocation to the plasma membrane and its peripheral association with Rac1 requires Nck1. Our studies underscore a coordinated mechanism for β2-chimaerin activation that involves lipid interactions via the C1 domain and protein-protein interactions via the N-terminal Pro-rich region.
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Affiliation(s)
- Alvaro Gutierrez-Uzquiza
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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12
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Xiang H, Li X, Dai F, Xu X, Tan A, Chen L, Zhang G, Ding Y, Li Q, Lian J, Willden A, Guo Q, Xia Q, Wang J, Wang W. Comparative methylomics between domesticated and wild silkworms implies possible epigenetic influences on silkworm domestication. BMC Genomics 2013; 14:646. [PMID: 24059350 PMCID: PMC3852238 DOI: 10.1186/1471-2164-14-646] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 09/04/2013] [Indexed: 11/13/2022] Open
Abstract
Background In contrast to wild species, which have typically evolved phenotypes over long periods of natural selection, domesticates rapidly gained human-preferred agronomic traits in a relatively short-time frame via artificial selection. Under domesticated conditions, many traits can be observed that cannot only be due to environmental alteration. In the case of silkworms, aside from genetic divergence, whether epigenetic divergence played a role in domestication is an unanswered question. The silkworm is still an enigma in that it has two DNA methyltransferases (DNMT1 and DNMT2) but their functionality is unknown. Even in particular the functionality of the widely distributed DNMT1 remains unknown in insects in general. Results By embryonic RNA interference, we reveal that knockdown of silkworm Dnmt1 caused decreased hatchability, providing the first direct experimental evidence of functional significance of insect Dnmt1. In the light of this fact and those that DNA methylation is correlated with gene expression in silkworms and some agronomic traits in domesticated organisms are not stable, we comprehensively compare silk gland methylomes of 3 domesticated (Bombyx mori) and 4 wild (Bombyx mandarina) silkworms to identify differentially methylated genes between the two. We observed 2-fold more differentiated methylated cytosinces (mCs) in domesticated silkworms as compared to their wild counterparts, suggesting a trend of increasing DNA methylation during domestication. Further study of more domesticated and wild silkworms narrowed down the domesticates’ epimutations, and we were able to identify a number of differential genes. One such gene showing demethyaltion in domesticates correspondently displays lower gene expression, and more interestingly, has experienced selective sweep. A methylation-increased gene seems to result in higher expression in domesticates and the function of its Drosophila homolog was previously found to be essential for cell volume regulation, indicating a possible correlation with the enlargement of silk glands in domesticated silkworms. Conclusions Our results imply epigenetic influences at work during domestication, which gives insight into long time historical controversies regarding acquired inheritance.
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Affiliation(s)
- Hui Xiang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 East Jiaochang Road, Kunming, Yunnan Province 650223, China.
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13
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Procino G, Mastrofrancesco L, Tamma G, Lasorsa DR, Ranieri M, Stringini G, Emma F, Svelto M, Valenti G. Calcium-sensing receptor and aquaporin 2 interplay in hypercalciuria-associated renal concentrating defect in humans. An in vivo and in vitro study. PLoS One 2012; 7:e33145. [PMID: 22403735 PMCID: PMC3293925 DOI: 10.1371/journal.pone.0033145] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 02/10/2012] [Indexed: 01/08/2023] Open
Abstract
One mechanism proposed for reducing the risk of calcium renal stones is activation of the calcium-sensing receptor (CaR) on the apical membranes of collecting duct principal cells by high luminal calcium. This would reduce the abundance of aquaporin-2 (AQP2) and in turn the rate of water reabsorption. While evidence in cells and in hypercalciuric animal models supports this hypothesis, the relevance of the interplay between the CaR and AQP2 in humans is not clear. This paper reports for the first time a detailed correlation between urinary AQP2 excretion under acute vasopressin action (DDAVP treatment) in hypercalciuric subjects and in parallel analyzes AQP2-CaR crosstalk in a mouse collecting duct cell line (MCD4) expressing endogenous and functional CaR. In normocalciurics, DDAVP administration resulted in a significant increase in AQP2 excretion paralleled by an increase in urinary osmolality indicating a physiological response to DDAVP. In contrast, in hypercalciurics, baseline AQP2 excretion was high and did not significantly increase after DDAVP. Moreover DDAVP treatment was accompanied by a less pronounced increase in urinary osmolality. These data indicate reduced urinary concentrating ability in response to vasopressin in hypercalciurics. Consistent with these results, biotinylation experiments in MCD4 cells revealed that membrane AQP2 expression in unstimulated cells exposed to CaR agonists was higher than in control cells and did not increase significantly in response to short term exposure to forskolin (FK). Interestingly, we found that CaR activation by specific agonists reduced the increase in cAMP and prevented any reduction in Rho activity in response to FK, two crucial pathways for AQP2 translocation. These data support the hypothesis that CaR–AQP2 interplay represents an internal renal defense to mitigate the effects of hypercalciuria on the risk of calcium precipitation during antidiuresis. This mechanism and possibly reduced medulla tonicity may explain the lower concentrating ability observed in hypercalciuric patients.
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Affiliation(s)
- Giuseppe Procino
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Lisa Mastrofrancesco
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Domenica Rita Lasorsa
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | | | | | - Maria Svelto
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
- * E-mail:
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14
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Schedlbauer A, Gandini R, Kontaxis G, Paulmichl M, Furst J, Konrat R. The C-terminus of ICln is natively disordered but displays local structural preformation. Cell Physiol Biochem 2011; 28:1203-10. [PMID: 22179008 DOI: 10.1159/000335852] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2011] [Indexed: 11/19/2022] Open
Abstract
ICln is a vital, ubiquitously expressed protein with roles in cell volume regulation, angiogenesis, cell morphology, activation of platelets and RNA processing. In previous work we have determined the 3D structure of the N-terminus of ICln (residues 1-159), which folds into a PH-like domain followed by an unstructured region (residues H134 - Q159) containing protein-protein interaction sites. Here we present sequence-specific resonance assignments of the C-terminus (residues Q159 - H235) of ICln by NMR, and show that this region of the protein is intrinsically unstructured. By applying (13)Cα- (13)Cβ secondary chemical shifts to detect possible preferences for secondary structure elements we show that the C-terminus of ICln adopts a preferred α-helical organization between residues E170 and E187, and exists preferentially in extended conformations (β-strands) between residues D161 to Y168 and E217 to T223.
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15
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Tamma G, Dossena S, Nofziger C, Valenti G, Svelto M, Paulmichl M. EGF stimulates IClswell by a redistribution of proteins involved in cell volume regulation. Cell Physiol Biochem 2011; 28:1191-202. [PMID: 22179007 DOI: 10.1159/000335851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2011] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND ICln is a multifunctional protein involved in the generation of chloride currents activated during regulatory volume decrease (RVD) after cell swelling (ICl(swell)). Growth factor receptors play a key role in different cellular processes and epidermal growth factor (EGF) regulates swelling-activated chloride permeability. AIM We set out to investigate if the EGF-induced upregulation of ICl(swell) could be explained by a rearrangement of ICln subcellular distribution and interaction with its molecular partners. METHODS NIH-3T3 fibroblasts were serum-deprived for 24 hours and stimulated with EGF (40 ng/ml) for 30 minutes. ICl(swell) activation, ICln distribution and interaction with its molecular partner HSPC038 were assessed by whole cell patch clamp and fluorescence resonance energy transfer (FRET). RESULTS EGF treatment significantly enhanced the direct molecular interaction between ICln and HSPC038 and also resulted in an increase of ICln and HSPC038 association with the plasma membrane. Importantly, these events are associated with a significant increase of ICl(swell). CONCLUSIONS The present data indicate that EGF might exert its role in the modulation of volume-sensitive chloride currents in part through activation and translocation of ICln and HSPC038 to the plasma membrane.
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Affiliation(s)
- Grazia Tamma
- Department of General and Environmental Physiology, University of Bari, Bari
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16
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Dossena S, Gandini R, Tamma G, Vezzoli V, Nofziger C, Tamplenizza M, Salvioni E, Bernardinelli E, Meyer G, Valenti G, Wolf-Watz M, Fürst J, Paulmichl M. The molecular and functional interaction between ICln and HSPC038 proteins modulates the regulation of cell volume. J Biol Chem 2011; 286:40659-70. [PMID: 21917931 PMCID: PMC3220508 DOI: 10.1074/jbc.m111.260430] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Identifying functional partners for protein/protein interactions can be a difficult challenge. We proposed the use of the operon structure of the Caenorhabditis elegans genome as a “new gene-finding tool” (Eichmüller, S., Vezzoli, V., Bazzini, C., Ritter, M., Fürst, J., Jakab, M., Ravasio, A., Chwatal, S., Dossena, S., Bottà, G., Meyer, G., Maier, B., Valenti, G., Lang, F., and Paulmichl, M. (2004) J. Biol. Chem. 279, 7136–7146) that could be functionally translated to the human system. Here we show the validity of this approach by studying the predicted functional interaction between ICln and HSPC038. In C. elegans, the gene encoding for the ICln homolog (icln-1) is embedded in an operon with two other genes, Nx (the human homolog of Nx is HSPC038) and Ny. ICln is a highly conserved, ubiquitously expressed multifunctional protein that plays a critical role in the regulatory volume decrease after cell swelling. Following hypotonic stress, ICln translocates from the cytosol to the plasma membrane, where it has been proposed to participate in the activation of the swelling-induced chloride current (IClswell). Here we show that the interaction between human ICln and HSPC038 plays a role in volume regulation after cell swelling and that HSPC038 acts as an escort, directing ICln to the cell membrane after cell swelling and facilitating the activation of IClswell. Assessment of the NMR structure of HSPC038 showed the presence of a zinc finger motif. Moreover, NMR and additional biochemical techniques enabled us to identify the putative ICln/HSPC038 interacting sites, thereby explaining the functional interaction of both proteins on a molecular level.
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Affiliation(s)
- Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, A-5020 Salzburg, Austria.
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17
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Procino G, Barbieri C, Carmosino M, Tamma G, Milano S, De Benedictis L, Mola MG, Lazo-Fernandez Y, Valenti G, Svelto M. Fluvastatin modulates renal water reabsorption in vivo through increased AQP2 availability at the apical plasma membrane of collecting duct cells. Pflugers Arch 2011; 462:753-66. [PMID: 21858457 DOI: 10.1007/s00424-011-1007-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 07/28/2011] [Accepted: 08/01/2011] [Indexed: 01/20/2023]
Abstract
X-linked nephrogenic diabetes insipidus (XNDI), a severe pathological condition characterized by greatly impaired urine-concentrating ability of the kidney, is caused by inactivating mutations in the V2 vasopressin receptor (V2R) gene. The lack of functional V2Rs prevents vasopressin-induced shuttling of aquaporin-2 (AQP2) water channels to the apical plasma membrane of kidney collecting duct principal cells, thus promoting water reabsorption from urine to the interstitium. At present, no specific pharmacological therapy exists for the treatment of XNDI. We have previously reported that the cholesterol-lowering drug lovastatin increases AQP2 membrane expression in renal cells in vitro. Here we report the novel finding that fluvastatin, another member of the statins family, greatly increases kidney water reabsorption in vivo in mice in a vasopressin-independent fashion. Consistent with this observation, fluvastatin is able to increase AQP2 membrane expression in the collecting duct of treated mice. Additional in vivo and in vitro experiments indicate that these effects of fluvastatin are most likely caused by fluvastatin-dependent changes in the prenylation status of key proteins regulating AQP2 trafficking in collecting duct cells. We identified members of the Rho and Rab families of proteins as possible candidates whose reduced prenylation might result in the accumulation of AQP2 at the plasma membrane. In conclusion, these results strongly suggest that fluvastatin, or other drugs of the statin family, may prove useful in the therapy of XNDI.
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Affiliation(s)
- Giuseppe Procino
- Department of General and Environmental Physiology, University of Bari, Bari, Italy.
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18
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Tamma G, Lasorsa D, Ranieri M, Mastrofrancesco L, Valenti G, Svelto M. Integrin signaling modulates AQP2 trafficking via Arg-Gly-Asp (RGD) motif. Cell Physiol Biochem 2011; 27:739-48. [PMID: 21691091 DOI: 10.1159/000330082] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2011] [Indexed: 12/20/2022] Open
Abstract
Aquaporin-2 (AQP2) increases the water permeability of renal collecting ducts in response to vasopressin. Vasopressin stimulation is accompanied by a profound remodeling of actin cytoskeleton whose dynamics are regulated by crosstalk between intracellular and extracellular signals. Here, we report that AQP2 contains a conserved RGD domain in its external C-loop. Co-immunoprecipitation experiments demonstrated that AQP2 binds integrin β1 in renal tissue and in MCD4 cells. To investigate the role of this interaction on AQP2 trafficking, cells were exposed to synthetic RGD-containing peptides, GRGDNP or GRGDSP, able to bind certain integrins. Incubation with these peptides increased the membrane expression of AQP2 in the absence of hormonal stimulation as assessed by confocal analysis and cell surface biotinylation. To identify the signals underlying the effects of peptides on AQP2 trafficking, some possible intracellular messengers were evaluated. Exposure of MCD4 cells to GRGDNP increased intracellular cAMP as assessed by FRET studies while GRGDSP increased intracellular calcium concentration. Taken together, these data propose integrins as new players controlling the cellular localization of AQP2, via two distinct signal transduction pathways dependent on cAMP and calcium respectively.
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Affiliation(s)
- Grazia Tamma
- Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, 70125 Bari, Italy.
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19
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Brumós J, Talón M, Bouhlal R, Colmenero-Flores JM. Cl- homeostasis in includer and excluder citrus rootstocks: transport mechanisms and identification of candidate genes. PLANT, CELL & ENVIRONMENT 2010; 33:2012-27. [PMID: 20573047 DOI: 10.1111/j.1365-3040.2010.02202.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To reveal specific Cl(-) transport activities in the symplastic pathway, uptake, long-distance transport and distribution of Cl(-) have been investigated in the citrus rootstocks Carrizo citrange (CC, Cl(-) includer) and Cleopatra mandarin (CM, Cl(-) excluder). Using an external concentration of 4.5 mm Cl(-) , both species actively transported Cl(-) to levels that exceeded the critical requirement concentration by one and two orders of magnitude in the excluder and the includer rootstocks, respectively. Both CC and CM modulated Cl(-) influx according to the availability of the nutrient as uptake capacity was induced by Cl(-) starvation, but inhibited after Cl(-) resupply. Net Cl(-) uptake was higher in the includer CC, an observation that correlated with a lower root-to-shoot transport capacity in the excluder CM. The patterns of tissue Cl(-) accumulation indicated that chloride exclusion in the salt-tolerant rootstock CM was caused by a reduced net Cl(-) loading into the root xylem. Genes CcCCC1, CcSLAH1 and CcICln1 putatively involved in the regulation of chloride transport were isolated and their expression analysed in response to both changes in the nutritional status of Cl(-) and salt stress. The previously uncharacterized ICln gene exhibited a strong repression to Cl(-) application in the excluder rootstock, suggesting a role in regulating Cl(-) homeostasis in plants.
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Affiliation(s)
- Javier Brumós
- Instituto Valenciano de Investigaciones Agrarias, Centro de Genómica, Valencia, Spain
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20
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Rid R, Onder K, Trost A, Bauer J, Hintner H, Ritter M, Jakab M, Costa I, Reischl W, Richter K, MacDonald S, Jendrach M, Bereiter-Hahn J, Breitenbach M. H2O2-dependent translocation of TCTP into the nucleus enables its interaction with VDR in human keratinocytes: TCTP as a further module in calcitriol signalling. J Steroid Biochem Mol Biol 2010; 118:29-40. [PMID: 19815065 DOI: 10.1016/j.jsbmb.2009.09.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2009] [Revised: 09/27/2009] [Accepted: 09/29/2009] [Indexed: 01/07/2023]
Abstract
Translationally controlled tumour protein (TCTP) is an evolutionarily highly conserved molecule implicated in many processes related to cell cycle progression, proliferation and growth, to the protection against harmful conditions including apoptosis and to the human allergic response. We are showing here that after application of mild oxidative stress, human TCTP relocates from the cytoplasm to the nuclei of HaCaT keratinocytes where it directly associates with the ligand-binding domain of endogenous vitamin D(3) receptor (VDR) through its helical domain 2 (AA 71-132). Interestingly, the latter harbours a putative nuclear hormone receptor coregulatory LxxLL-like motif which seems to be involved in the interaction. Moreover, we demonstrate that VDR transcriptionally induces the expression of TCTP by binding to a previously unknown VDR response element within the TCTP promotor. Conversely, ectopically overexpressed TCTP downregulates the amount of VDR on both mRNA as well as protein level. These data, to conclude, suggest a kind of feedback regulation between TCTP and VDR to regulate a variety of (Ca(2+) dependent) cellular effects and in this way further underscore the physiological relevance of this novel protein-protein interaction.
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MESH Headings
- Active Transport, Cell Nucleus/drug effects
- Active Transport, Cell Nucleus/physiology
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Calcitriol/pharmacology
- Calcitriol/physiology
- Cell Line, Transformed
- Cell Nucleus/metabolism
- Cytoplasm/metabolism
- DNA/metabolism
- Electrophoretic Mobility Shift Assay
- Feedback, Physiological/physiology
- Fluorescence Resonance Energy Transfer
- Gene Expression/genetics
- Gene Expression Regulation, Neoplastic/physiology
- Humans
- Hydrogen Peroxide/pharmacology
- Immunoprecipitation
- Keratinocytes/drug effects
- Keratinocytes/metabolism
- Oxidative Stress/drug effects
- Oxidative Stress/physiology
- Promoter Regions, Genetic/genetics
- Protein Binding/drug effects
- Protein Binding/physiology
- Protein Interaction Domains and Motifs/physiology
- Receptors, Calcitriol/genetics
- Receptors, Calcitriol/metabolism
- Recombinant Proteins/metabolism
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Tumor Protein, Translationally-Controlled 1
- Two-Hybrid System Techniques
- Vitamin D Response Element/genetics
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Affiliation(s)
- Raphaela Rid
- Department of Cell Biology, Division of Genetics, University of Salzburg, Salzburg, Austria
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21
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Ischemia’s Proliferative and Morphological Effects: Analyzing the Roles of Hypoxia, Hypercapnia, and Glucose. Cell Mol Bioeng 2009. [DOI: 10.1007/s12195-009-0098-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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22
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Li YH, Eto K, Horikawa S, Uchida S, Sasaki S, Li XJ, Noda Y. Aquaporin-2 regulates cell volume recovery via tropomyosin. Int J Biochem Cell Biol 2009; 41:2466-76. [DOI: 10.1016/j.biocel.2009.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 07/06/2009] [Accepted: 07/23/2009] [Indexed: 12/01/2022]
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23
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Trost A, Costa I, Jakab M, Ritter M, Haim M, Hintner H, Bauer JW, Önder K. K16 is a further new candidate for homotypic intermediate filament protein interactions. Exp Dermatol 2009; 19:e241-50. [DOI: 10.1111/j.1600-0625.2010.01071.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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24
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Tejada-Jiménez M, Galván A, Fernández E, Llamas A. Homeostasis of the micronutrients Ni, Mo and Cl with specific biochemical functions. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:358-363. [PMID: 19487155 DOI: 10.1016/j.pbi.2009.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 04/27/2009] [Accepted: 04/27/2009] [Indexed: 05/27/2023]
Abstract
Homeostasis of three elements nickel, molybdenum and chloride is analysed. These micronutrients, at amounts varying in orders of magnitude, fulfil important cell functions. In general terms, cells use similar strategies to ensure that the elements are within physiological ranges avoiding high toxic concentrations. These strategies correspond to specific carriers, channels and pumps, intermediate steps (chelating/sequestration/binding/metabolic conversion/storage), final steps related to specific enzyme functionality and putative sensing proteins. Single cell homeostasis, coordinated with an efficient redistribution by xylem loading, ensures in turn homeostasis at the whole plant level. Recent advances are based on the molecular identification of some key components.
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Affiliation(s)
- Manuel Tejada-Jiménez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Campus de Rabanales, Córdoba, Spain
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25
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Fujimoto W, Miki T, Ogura T, Zhang M, Seino Y, Satin LS, Nakaya H, Seino S. Niflumic acid-sensitive ion channels play an important role in the induction of glucose-stimulated insulin secretion by cyclic AMP in mice. Diabetologia 2009; 52:863-72. [PMID: 19266181 PMCID: PMC4696557 DOI: 10.1007/s00125-009-1306-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Accepted: 02/08/2009] [Indexed: 01/27/2023]
Abstract
AIMS/HYPOTHESIS We have previously reported that glucose-stimulated insulin secretion (GSIS) is induced by glucagon-like peptide-1 (GLP-1) in mice lacking ATP-sensitive K(+) (K(ATP)) channels (Kir6.2(-/-) mice [up-to-date symbol for Kir6.2 gene is Kcnj11]), in which glucose alone does not trigger insulin secretion. This study aimed to clarify the mechanism involved in the induction of GSIS by GLP-1. METHODS Pancreas perfusion experiments were performed using wild-type (Kir6.2(+/+)) or Kir6.2(-/-) mice. Glucose concentrations were either changed abruptly from 2.8 to 16.7 mmol/l or increased stepwise (1.4 mmol/l per step) from 2.8 to 12.5 mmol/l. Electrophysiological experiments were performed using pancreatic beta cells isolated from Kir6.2(-/-) mice or clonal pancreatic beta cells (MIN6 cells) after pharmacologically inhibiting their K(ATP) channels with glibenclamide. RESULTS The combination of cyclic AMP plus 16.7 mmol/l glucose evoked insulin secretion in Kir6.2(-/-) pancreases where glucose alone was ineffective as a secretagogue. The secretion was blocked by the application of niflumic acid. In K(ATP) channel-inactivated MIN6 cells, niflumic acid similarly inhibited the membrane depolarisation caused by cAMP plus glucose. Surprisingly, stepwise increases of glucose concentration triggered insulin secretion only in the presence of cAMP or GLP-1 in Kir6.2(+/+), as in Kir6.2(-/-) pancreases. CONCLUSIONS/INTERPRETATION Niflumic acid-sensitive ion channels participate in the induction of GSIS by cyclic AMP in Kir6.2(-/-) beta cells. Cyclic AMP thus not only acts as a potentiator of insulin secretion, but appears to be permissive for GSIS via novel, niflumic acid-sensitive ion channels. This mechanism may be physiologically important for triggering insulin secretion when the plasma glucose concentration increases gradually rather than abruptly.
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Affiliation(s)
- W. Fujimoto
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - T. Miki
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
- Department of Autonomic Physiology (C3), Graduate School of Medicine, Chiba University, Chiba, Japan
| | - T. Ogura
- Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - M. Zhang
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Y. Seino
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
- Division of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - L. S. Satin
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - H. Nakaya
- Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - S. Seino
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
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Larkin D, Treumann A, Murphy D, DeChaumont C, Kiernan A, Moran N. Compartmentalization regulates the interaction between the platelet integrin alpha IIb beta 3 and ICln. Br J Haematol 2008; 144:580-90. [PMID: 19055659 DOI: 10.1111/j.1365-2141.2008.07483.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The volume-regulating protein, ICln, interacts with the conserved KxGFFKR alpha-integrin signature motif. ICln is an abundant protein (4455 +/- 650 molecules/platelet) found exclusively in the soluble cytosolic fraction of unactivated platelets. In contrast, its binding partner, the platelet integrin alpha(IIb)beta(3), is present in detergent-insoluble fractions associated with membrane and cytoskeleton subcellular localizations. This study investigated factors that regulate the interaction of ICln with alpha(IIb)beta(3) during platelet activation. His-tagged recombinant ICln bound equally to purified alpha(IIb)beta(3) and to integrin from resting or activated platelets. Binding was not affected by direct integrin activation with Mn(++) or by inhibitors of integrin occupancy (abciximab, RGD). However, the capacity for interaction between integrin and recombinant ICln was slowly downregulated following prolonged platelet activation for >300 s. In parallel, ICln redistributed to membrane and cytoskeletal platelet subcellular fractions. The time-course of this redistribution preceded the downregulation of integrin binding capacity and suggests that only a short window of opportunity exists for ICln interaction with alpha(IIb)beta(3) to occur. Thus, although ICln has the inherent capacity to bind to alpha(IIb)beta(3) regardless of its activation state, it can only do so following platelet activation. Activation-dependent subcellular redistribution of ICln represents a novel, temporally-regulated mechanism for control of integrin function in platelets.
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Affiliation(s)
- Deirdre Larkin
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
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27
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Rodighiero S, Bazzini C, Ritter M, Fürst J, Botta G, Meyer G, Paulmichl M. Fixation, mounting and sealing with nail polish of cell specimens lead to incorrect FRET measurements using acceptor photobleaching. Cell Physiol Biochem 2008; 21:489-98. [PMID: 18453757 DOI: 10.1159/000129642] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2008] [Indexed: 11/19/2022] Open
Abstract
Fluorescence resonance energy transfer (FRET) is a technique used for the study of functional interactions between molecules. The intimate vicinity between two fluorescent molecules (FRET-pair; donor and acceptor) allows for an energy transfer, which can be directly calculated as the so called FRET efficiency. This technique is used in fixed as well as living cells. Here we show first, measured by the FRET technique, that the ICln ion channel is transposed from the cytosol towards the cellular membrane in HEK cells after swelling, and second, that the calculation of the FRET efficiency by de-quenching the donor cyan-fluorescent-protein (CFP) emission due to acceptor-photobleaching leads to erroneous estimate of the FRET efficiency in fixed, mounted and sealed specimens. The acceptor photobleaching leads to a modification of the donor cyan-fluorescent-protein, which shows then a strong emission, thus mimicking functional interaction between CFP (donor) and yellow-fluorescent-protein (YFP; acceptor). Moreover, the procedure of acceptor photobleaching masks physiological (non random) interaction between molecules within the fixed, mounted and sealed cell. We show that no artifactual CFP modifications arise when using the acceptor photobleaching technique under in vivo conditions, and we offer strategies to minimize erroneous FRET efficiency calculations if cells need to be fixed.
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Abstract
Chloride channels represent a relatively under-explored target class for drug discovery as elucidation of their identity and physiological roles has lagged behind that of many other drug targets. Chloride channels are involved in a wide range of biological functions, including epithelial fluid secretion, cell-volume regulation, neuroexcitation, smooth-muscle contraction and acidification of intracellular organelles. Mutations in several chloride channels cause human diseases, including cystic fibrosis, macular degeneration, myotonia, kidney stones, renal salt wasting and hyperekplexia. Chloride-channel modulators have potential applications in the treatment of some of these disorders, as well as in secretory diarrhoeas, polycystic kidney disease, osteoporosis and hypertension. Modulators of GABA(A) (gamma-aminobutyric acid A) receptor chloride channels are in clinical use and several small-molecule chloride-channel modulators are in preclinical development and clinical trials. Here, we discuss the broad opportunities that remain in chloride-channel-based drug discovery.
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Affiliation(s)
- Alan S Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, California 94143-0521, USA.
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29
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Lang F, Gulbins E, Szabo I, Vereninov A, Huber SM. Ion Channels, Cell Volume, Cell Proliferation and Apoptotic Cell Death. SENSING WITH ION CHANNELS 2008. [DOI: 10.1007/978-3-540-72739-2_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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30
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Abstract
Survival of human and animal cells requires avoidance of excessive alterations of cell volume. The osmolarity amassed by cellular accumulation of organic substances must be compensated by lowering cytosolic ion concentrations. The Na+/K+ ATPase extrudes Na+ in exchange for K+, which can permeate the cell membrane through K+ channels. K+ exit generates a cell-negative potential difference across the cell membrane, driving the exit of anions such as Cl-. The low cytosolic Cl- concentrations counterbalance the excess cellular osmolarity by organic substances. Cell volume regulation following cell swelling involves releasing ions through activation of K+ channels and/or anion channels, KCl-cotransport, or parallel activation of K+/H+ exchange and Cl-/HCO3- exchange. Cell volume regulation following cell shrinkage involves accumulation of ions through activation of Na+,K+,2Cl- cotransport, Na+/H+ exchange in parallel to Cl-/HCO3- exchange, or Na+ channels. The Na+ taken up is extruded by the Na+/K+ ATPase in exchange for K+. Shrunken cells further accumulate organic osmolytes such as sorbitol and glycerophosphorylcholine, and monomeric amino acids by altered metabolism and myoinositol (inositol), betaine, taurine, and amino acids by Na+ coupled transport. They release osmolytes during cell swelling. Challenges of cell volume homeostasis include transport, hormones, transmitters, and drugs. Moreover, alterations of cell volume participate in the machinery regulating cell proliferation and apoptotic cell death. Deranged cell volume regulation significantly contributes to the pathophysiology of several disorders such as liver insufficiency, diabetic ketoacidosis, hypercatabolism, fibrosing disease, sickle cell anemia, and infection.
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Affiliation(s)
- Florian Lang
- Department of Physiology I, University of Tübingen, Tübingen, Germany.
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31
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Rivera A, De Franceschi L, Peters LL, Gascard P, Mohandas N, Brugnara C. Effect of complete protein 4.1R deficiency on ion transport properties of murine erythrocytes. Am J Physiol Cell Physiol 2006; 291:C880-6. [PMID: 16774987 DOI: 10.1152/ajpcell.00436.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Moderate hemolytic anemia, abnormal erythrocyte morphology (spherocytosis), and decreased membrane stability are observed in mice with complete deficiency of all erythroid protein 4.1 protein isoforms (4.1(-/-); Shi TS et al. J Clin Invest 103: 331, 1999). We have examined the effects of erythroid protein 4.1 (4.1R) deficiency on erythrocyte cation transport and volume regulation. 4.1(-/-) mice exhibited erythrocyte dehydration that was associated with reduced cellular K and increased Na content. Increased Na permeability was observed in these mice, mostly mediated by Na/H exchange with normal Na-K pump and Na-K-2Cl cotransport activities. The Na/H exchange of 4.1(-/-) erythrocytes was markedly activated by exposure to hypertonic conditions (18.2 +/- 3.2 in 4.1(-/-) vs. 9.8 +/- 1.3 mmol/10(13) cell x h in control mice), with an abnormal dependence on osmolality (EC(50) = 417 +/- 42 in 4.1(-/-) vs. 460 +/- 35 mosmol/kgH(2)O in control mice), suggestive of an upregulated functional state. While the affinity for internal protons was not altered (K(0.5) = 489.7 +/- 0.7 vs. 537.0 +/- 0.56 nM in control mice), the V(max) of the H-induced Na/H exchange activity was markedly elevated in 4.1(-/-) erythrocytes (V(max) 91.47 +/- 7.2 compared with 46.52 +/- 5.4 mmol/10(13) cell x h in control mice). Na/H exchange activation by okadaic acid was absent in 4.1(-/-) erythrocytes. Altogether, these results suggest that erythroid protein 4.1 plays a major role in volume regulation and physiologically downregulates Na/H exchange in mouse erythrocytes. Upregulation of the Na/H exchange is an important contributor to the elevated cell Na content of 4.1(-/-) erythrocytes.
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Affiliation(s)
- Alicia Rivera
- Children's Hospital Boston, Dept. of Laboratory Medicine, Harvard Medical School, Boston, MA 02115, USA.
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32
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Jakab M, Grundbichler M, Benicky J, Ravasio A, Chwatal S, Schmidt S, Strbak V, Fürst J, Paulmichl M, Ritter M. Glucose induces anion conductance and cytosol-to-membrane transposition of ICln in INS-1E rat insulinoma cells. Cell Physiol Biochem 2006; 18:21-34. [PMID: 16914887 DOI: 10.1159/000095131] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The metabolic coupling of insulin secretion by pancreatic beta cells is mediated by membrane depolarization due to increased glucose-driven ATP production and closure of K(ATP) channels. Alternative pathways may involve the activation of anion channels by cell swelling upon glucose uptake. In INS-1E insulinoma cells superfusion with an isotonic solution containing 20 mM glucose or a 30% hypotonic solution leads to the activation of a chloride conductance with biophysical and pharmacological properties of anion currents activated in many other cell types during regulatory volume decrease (RVD), i.e. outward rectification, inactivation at positive membrane potentials and block by anion channel inhibitors like NPPB, DIDS, 4-hydroxytamoxifen and extracellular ATP. The current is not inhibited by tolbutamide and remains activated for at least 10 min when reducing the extracellular glucose concentration from 20 mM to 5 mM, but inactivates back to control levels when cells are exposed to a 20% hypertonic extracellular solution containing 20 mM glucose. This chloride current can likewise be induced by 20 mM 3-Omethylglucose, which is taken up but not metabolized by the cells, suggesting that cellular sugar uptake is involved in current activation. Fluorescence resonance energy transfer (FRET) experiments show that chloride current activation by 20 mM glucose and glucose-induced cell swelling are accompanied by a significant, transient redistribution of the membrane associated fraction of ICln, a multifunctional 'connector hub' protein involved in cell volume regulation and generation of RVD currents.
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Affiliation(s)
- Martin Jakab
- Institute of Physiology and Pathophysiology, Paracelsus Private Medical University, Salzburg
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33
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Fürst J, Bottà G, Saino S, Dopinto S, Gandini R, Dossena S, Vezzoli V, Rodighiero S, Bazzini C, Garavaglia ML, Meyer G, Jakab M, Ritter M, Wappl-Kornherr E, Paulmichl M. The ICln interactome. Acta Physiol (Oxf) 2006; 187:43-9. [PMID: 16734741 DOI: 10.1111/j.1748-1716.2006.01549.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The many different functional phenotypes described in mammalian cells can only be explained by an intense interaction of the underlying proteins, substantiated by the fact that the number of independently expressed proteins in living cells seems not to exceed 25 K, a number way too small to explain the >250 K different phenotypes on a one-protein-one-function base. Therefore, the study of the interactome of the different proteins is of utmost importance. Here, we describe the present knowledge of the ICln interactome. ICln is a protein, we cloned and whose function was reported to be as divers as (i) ion permeation, (ii) cytoskeletal organization, and (iii) RNA processing. The role of ICln in these different functional modules can be described best as being a 'connector hub' with 'date hub' function.
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Affiliation(s)
- J Fürst
- Department of Physiology and Medical Physics, Innsbruck Medical University, Innsbruck, Austria
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34
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Fürst J, Schedlbauer A, Gandini R, Garavaglia ML, Saino S, Gschwentner M, Sarg B, Lindner H, Jakab M, Ritter M, Bazzini C, Botta G, Meyer G, Kontaxis G, Tilly BC, Konrat R, Paulmichl M. ICln159 folds into a pleckstrin homology domain-like structure. Interaction with kinases and the splicing factor LSm4. J Biol Chem 2005; 280:31276-82. [PMID: 15905169 DOI: 10.1074/jbc.m500541200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ICln is a multifunctional protein involved in regulatory mechanisms as different as membrane ion transport and RNA splicing. The protein is water-soluble, and during regulatory volume decrease after cell swelling, it is able to migrate from the cytosol to the cell membrane. Purified, water-soluble ICln is able to insert into lipid bilayers to form ion channels. Here, we show that ICln159, a truncated ICln mutant, which is also able to form ion channels in lipid bilayers, belongs to the pleckstrin homology (PH) domain superfold family of proteins. The ICln PH domain shows unusual properties as it lacks the electrostatic surface polarization seen in classical PH domains. However, similar to many classical PH domain-containing proteins, ICln interacts with protein kinase C, and in addition, interacts with cAMP-dependent protein kinase and cGMP-dependent protein kinase type II but not cGMP-dependent protein kinase type Ibeta. A major phosphorylation site for all three kinases is Ser-45 within the ICln PH domain. Furthermore, ICln159 interacts with LSm4, a protein involved in splicing and mRNA degradation, suggesting that the ICln159 PH domain may serve as a protein-protein interaction platform.
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Affiliation(s)
- Johannes Fürst
- Department of Physiology and Medical Physics, Innsbruck Medical University, Fritz-Pregl Strasse 3, A-6020 Innsbruck, Austria
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35
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Liu R, Carretero OA, Ren Y, Garvin JL. Increased intracellular pH at the macula densa activates nNOS during tubuloglomerular feedback. Kidney Int 2005; 67:1837-43. [PMID: 15840031 DOI: 10.1111/j.1523-1755.2005.00282.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The macula densa senses increasing NaCl concentrations in tubular fluid and increases afferent arteriole tone by a process known as tubuloglomerular feedback (TGF). Nitric oxide (NO) production by macula densa neuronal nitric oxide synthase (nNOS) is enhanced by increasing NaCl in the macula densa lumen, and the NO thus formed inhibits TGF. Blocking apical Na(+)/H(+) exchange with amiloride augments TGF and mimics the effect of nNOS inhibition. We hypothesized that increasing NaCl in the macula densa lumen raises macula densa intracellular pH (pH(i)) and activates nNOS. METHODS The thick ascending limb and a portion of the distal tubule with intact macula densa plaque adherent to the glomerulus were microdissected and perfused. Macula densa perfusate was changed from a low (10 mmol/L) to high NaCl solution (80 mmol/L) to mimic the conditions that induce TGF. Osmolality of both solutions was 180 mOsm, so that changing the solutions did not alter cell volume. RESULTS Macula densa pH(i) increased significantly from 7.0 +/- 0.5 to 7.8 +/- 0.6 when the perfusate was changed from low to high (P < 0.05; N= 5). When amiloride was added to inhibit Na(+)/H(+) exchange, the increase in pH(i) during TGF was blocked (N= 5). Fluorescence intensity of DAF-2, an NO-sensitive dye, increased by 28.8 +/- 4.1% after increasing luminal NaCl (N= 5), indicating an increase in NO production. In the presence of the Na(+)/H(+) exchanger inhibitor amiloride or the nNOS inhibitor 7-NI, the increase in NO induced by switching the macula densa perfusate from low to high was blunted. To study whether changes in pH(i) can directly alter NO production, we used nigericin, a K(+)/H(+) ionophore, to equilibrate luminal and intracellular pH. When macula densa pH was raised from 7.3 to 7.8 in the presence of 10(-5) mol/L nigericin in the low NaCl solution, fluorescence of DAF-2 in the macula densa increased by 17.9 +/- 1.3% (P < 0.01; N= 5). In the presence of 7-NI, the increase in NO induced by raising pH(i) was blocked (N= 5). CONCLUSION We concluded that macula densa pH(i) increases during TGF, and this increase in pH(i) activates nNos.
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Affiliation(s)
- Ruisheng Liu
- Hypertension & Vascular Research Division, Henry Ford Hospital, Detroit, Michigan 48202, USA.
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Park JB, Son SJ, Lee GS, Cho PY, Song KS, Ryu PD, Kang SY, Hong SJ. Molecular and electrophysiological characterization of nucleotide-sensitive chloride current-inducing protein of Fasciola hepatica. Mol Biochem Parasitol 2005; 140:197-203. [PMID: 15760659 DOI: 10.1016/j.molbiopara.2005.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Accepted: 01/12/2005] [Indexed: 11/16/2022]
Abstract
Nucleotide-sensitive chloride current regulating proteins (ICln's) of the chloride channels have been characterized from man and animals. An ICln of Fasciola hepatica (ICln-Fh) consisting of 231 amino acids revealed high similarities to both consensus domain of ICln's and two acidic residue-abundant patches in its C-terminus. Native ICln-Fh protein was confirmed present in F. hepatica soluble extract by immunoblotting. The recombinant ICln-Fh protein expressed in collagenase-defolliculated Xenopus oocytes induced fast rising and outward rectifying Cl- currents (I(Cln-Fh)). The recombinant ICln-Fh protein, however, did not trigger cell swelling-induced Cl- currents (I(Cl-swell)). The I(Cln-Fh) currents were significantly reduced by substituting external Cl- with gluconic acid and by externally adding cAMP. Collectively, these results suggest that ICln-Fh protein is an inducer of Cl- currents in F. hepatica.
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Affiliation(s)
- Jin Bong Park
- Department of Physiology, College of Medicine, Chungnam National University, Taejeon 301-131, Republic of Korea
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37
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Larkin D, Murphy D, Reilly DF, Cahill M, Sattler E, Harriott P, Cahill DJ, Moran N. ICln, a Novel Integrin αIIbβ3-Associated Protein, Functionally Regulates Platelet Activation. J Biol Chem 2004; 279:27286-93. [PMID: 15075326 DOI: 10.1074/jbc.m402159200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A critical role for the conserved alpha-integrin cytoplasmic motif, KVGFFKR, is recognized in the regulation of activation of the platelet integrin alpha(IIb)beta(3). To understand the molecular mechanisms of this regulation, we sought to determine the nature of the protein interactions with this cytoplasmic motif. We used a tagged synthetic peptide, biotin-KVGFFKR, to probe a high density protein expression array (37,200 recombinant human proteins) for high affinity interactions. A number of potential integrin-binding proteins were identified. One such protein, a chloride channel regulatory protein, ICln, was characterized further because its affinity for the integrin peptide was highest as was its expression in platelets. We verified the presence of ICln in human platelets by PCR, Western blots, immunohistochemistry, and its co-association with alpha(IIb)beta(3) by surface plasmon resonance. The affinity of this interaction was 82.2 +/- 24.4 nm in a cell free assay. ICln co-immunoprecipitates with alpha(IIb)beta(3) in platelet lysates demonstrating that this interaction is physiologically relevant. Furthermore, immobilized KVGFFKR peptides, but not control KAAAAAR peptides, specifically extract ICln from platelet lysates. Acyclovir (100 microm to 5 mm), a pharmacological inhibitor of the ICln chloride channel, specifically inhibits integrin activation (PAC-1 expression) and platelet aggregation without affecting CD62 P expression confirming a specific role for ICln in integrin activation. In parallel, a cell-permeable peptide corresponding to the potential integrin-recognition domain on ICln (AKFEEE, 10-100 microm) also inhibits platelet function. Thus, we have identified, verified, and characterized a novel functional interaction between the platelet integrin and ICln, in the platelet membrane.
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Affiliation(s)
- Deirdre Larkin
- Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin
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Meyer G, Rodighiero S, Guizzardi F, Bazzini C, Bottà G, Bertocchi C, Garavaglia L, Dossena S, Manfredi R, Sironi C, Catania A, Paulmichl M. Volume-regulated Cl- channels in human pleural mesothelioma cells. FEBS Lett 2004; 559:45-50. [PMID: 14960305 DOI: 10.1016/s0014-5793(04)00020-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 12/17/2003] [Accepted: 01/05/2004] [Indexed: 11/28/2022]
Abstract
Anion channels in human mesothelial and mesothelioma cell lines were characterized by patch-clamp and biomolecular approaches. We found an outwardly rectifying anionic current which was inactivated at positive voltages and inhibited by extracellular adenosine 5'-triphosphate (ATP). Mesothelial and mesothelioma cells behaved differently concerning current inactivation properties. Inactivation is more pronounced and has a steeper onset in mesothelial cells. Different reversal potentials, in asymmetrical Cl(-) solutions, that could be attributed to a different selectivity of the channel, have been observed in the two cell lines. Mesothelioma cell single-channel analysis indicates that the number of the same active anion channel (3-4 pS) increased under hypoosmotic conditions. Immunocytochemistry experiments showed the presence of ICln protein in the cytosol and in the plasma membrane. Western blot analysis revealed an increase of ICln in the membrane under hypotonic conditions, an event possibly related to the activation of Cl(-) channels.
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Affiliation(s)
- Giuliano Meyer
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Via Celoria 26, I-20133 Milan, Italy.
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Sardini A, Amey JS, Weylandt KH, Nobles M, Valverde MA, Higgins CF. Cell volume regulation and swelling-activated chloride channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1618:153-62. [PMID: 14729152 DOI: 10.1016/j.bbamem.2003.10.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Maintenance of a constant volume is essential for normal cell function. Following cell swelling, as a consequence of reduction of extracellular osmolarity or increase of intracellular content of osmolytes, animal cells are able to restore their original volume by activation of potassium and chloride conductances. The loss of these ions, followed passively by water, is responsible for the homeostatic response called regulatory volume decrease (RVD). Activation of a chloride conductance upon cell swelling is a key step in RVD. Several proteins have been proposed as candidates for this chloride conductance. The status of the field is reviewed, with particular emphasis on ClC-3, a member of the ClC family which has been recently proposed as the chloride channel involved in cell volume regulation.
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Affiliation(s)
- Alessandro Sardini
- MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
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40
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Ritter M, Bertocchi C, Jakab M, Fürst J, Paulmichl M. Further characterization of the nematode IClnN2 protein reconstituted in lipid bilayers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 559:245-251. [PMID: 18727245 DOI: 10.1007/0-387-23752-6_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- M Ritter
- Institute of Physiology, University of Innsbruck, Fritz-Pregl Strasse 3, A-6020 Innsbruck, Austria.
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Eichmüller S, Vezzoli V, Bazzini C, Ritter M, Fürst J, Jakab M, Ravasio A, Chwatal S, Dossena S, Bottà G, Meyer G, Maier B, Valenti G, Lang F, Paulmichl M. A new gene-finding tool: using the Caenorhabditis elegans operons for identifying functional partner proteins in human cells. J Biol Chem 2003; 279:7136-46. [PMID: 14615488 DOI: 10.1074/jbc.m307347200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
How can a large number of different phenotypes be generated by a limited number of genotypes? Promiscuity between different, structurally related and/or unrelated proteins seems to provide a plausible explanation to this pertinent question. Strategies able to predict such functional interrelations between different proteins are important to restrict the number of putative candidate proteins, which can then be subjected to time-consuming functional tests. Here we describe the use of the operon structure of the nematode genome to identify partner proteins in human cells. In this work we focus on ion channels proteins, which build an interface between the cell and the outside world and are responsible for a growing number of diseases in humans. However, the proposed strategy for the partner protein quest is not restricted to this scientific area but can be adopted in virtually every field of human biology where protein-protein interactions are assumed.
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Affiliation(s)
- Sonja Eichmüller
- Institute of Physiology, University of Innsbruck, Fritz-Pregl Strasse 3, A-6020 Innsbruck, Austria
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