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Huang S, Balgi A, Pan Y, Li M, Zhang X, Du L, Zhou M, Roberge M, Li X. Identification of Methylosome Components as Negative Regulators of Plant Immunity Using Chemical Genetics. MOLECULAR PLANT 2016; 9:1620-1633. [PMID: 27756575 DOI: 10.1016/j.molp.2016.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 09/01/2016] [Accepted: 10/01/2016] [Indexed: 06/06/2023]
Abstract
Nucleotide-binding leucine-rich repeat (NLR) proteins serve as immune receptors in both plants and animals. To identify components required for NLR-mediated immunity, we designed and carried out a chemical genetics screen to search for small molecules that can alter immune responses in Arabidopsis thaliana. From 13 600 compounds, we identified Ro 8-4304 that was able to specifically suppress the severe autoimmune phenotypes of chs3-2D (chilling sensitive 3, 2D), including the arrested growth morphology and heightened PR (Pathogenesis Related) gene expression. Further, six Ro 8-4304 insensitive mutants were uncovered from the Ro 8-4304-insensitive mutant (rim) screen using a mutagenized chs3-2D population. Positional cloning revealed that rim1 encodes an allele of AtICln (I, currents; Cl, chloride; n, nucleotide). Genetic and biochemical analysis demonstrated that AtICln is in the same protein complex with the methylosome components small nuclear ribonucleoprotein D3b (SmD3b) and protein arginine methyltransferase 5 (PRMT5), which are required for the biogenesis of small nuclear ribonucleoproteins (snRNPs) involved in mRNA splicing. Double mutant analysis revealed that SmD3b is also involved in the sensitivity to Ro 8-4304, and the prmt5-1 chs3-2D double mutant is lethal. Loss of AtICln, SmD3b, or PRMT5 function results in enhanced disease resistance against the virulent oomycete pathogen Hyaloperonospora arabidopsidis Noco2, suggesting that mRNA splicing plays a previously unknown negative role in plant immunity. The successful implementation of a high-throughput chemical genetic screen and the identification of a small-molecule compound affecting plant immunity indicate that chemical genetics is a powerful tool to study whole-organism plant defense pathways.
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Affiliation(s)
- Shuai Huang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Aruna Balgi
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Yaping Pan
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng Li
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xiaoran Zhang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Lilin Du
- National Institute of Biological Sciences, Beijing 102206, China
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michel Roberge
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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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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3
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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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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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5
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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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6
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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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7
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d'Anglemont de Tassigny A, Souktani R, Ghaleh B, Henry P, Berdeaux A. Structure and pharmacology of swelling-sensitive chloride channels, I(Cl,swell). Fundam Clin Pharmacol 2004; 17:539-53. [PMID: 14703715 DOI: 10.1046/j.1472-8206.2003.00197.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Since several years, the interest for chloride channels and more particularly for the enigmatic swelling-activated chloride channel (I(Cl,swell)) is increasing. Despite its well-characterized electrophysiological properties, the I(Cl,swell) structure and pharmacology are not totally elucidated. These channels are involved in a variety of cell functions, such as cardiac rhythm, cell proliferation and differentiation, cell volume regulation and cell death through apoptosis. This review will consider different aspects regarding structure, electrophysiological properties, pharmacology, modulation and functions of these swelling-activated chloride channels.
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8
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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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9
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Wehner F, Olsen H, Tinel H, Kinne-Saffran E, Kinne RKH. Cell volume regulation: osmolytes, osmolyte transport, and signal transduction. Rev Physiol Biochem Pharmacol 2004; 148:1-80. [PMID: 12687402 DOI: 10.1007/s10254-003-0009-x] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In recent years, it has become evident that the volume of a given cell is an important factor not only in defining its intracellular osmolality and its shape, but also in defining other cellular functions, such as transepithelial transport, cell migration, cell growth, cell death, and the regulation of intracellular metabolism. In addition, besides inorganic osmolytes, the existence of organic osmolytes in cells has been discovered. Osmolyte transport systems-channels and carriers alike-have been identified and characterized at a molecular level and also, to a certain extent, the intracellular signals regulating osmolyte movements across the plasma membrane. The current review reflects these developments and focuses on the contributions of inorganic and organic osmolytes and their transport systems in regulatory volume increase (RVI) and regulatory volume decrease (RVD) in a variety of cells. Furthermore, the current knowledge on signal transduction in volume regulation is compiled, revealing an astonishing diversity in transport systems, as well as of regulatory signals. The information available indicates the existence of intricate spatial and temporal networks that control cell volume and that we are just beginning to be able to investigate and to understand.
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Affiliation(s)
- F Wehner
- Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
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10
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Ritter M, Ravasio A, Jakab M, Chwatal S, Fürst J, Laich A, Gschwentner M, Signorelli S, Burtscher C, Eichmüller S, Paulmichl M. Cell swelling stimulates cytosol to membrane transposition of ICln. J Biol Chem 2003; 278:50163-74. [PMID: 12970357 DOI: 10.1074/jbc.m300374200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [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 that is essential for cell volume regulation. It can be found in the cytosol and is associated with the cell membrane. Besides its role in the splicing process, ICln is critically involved in the generation of ion currents activated during regulatory volume decrease after cell swelling (RVDC). If reconstituted in artificial bilayers, ICln can form ion channels with biophysical properties related to RVDC. We investigated (i) the cytosol versus cell membrane distribution of ICln in rat kidney tubules, NIH 3T3 fibroblasts, Madin-Darby canine kidney (MDCK) cells, and LLC-PK1 epithelial cells, (ii) fluorescence resonance energy transfer (FRET) in living fibroblasts between fluorescently tagged ICln and fluorochromes in the cell membrane, and (iii) possible functional consequences of an enhanced ICln presence at the cell membrane. We demonstrate that ICln distribution in rat kidneys depends on the parenchymal localization and functional state of the tubules and that cell swelling causes ICln redistribution from the cytosol to the cell membrane in NIH 3T3 fibroblasts and LLC-PK1 cells. The addition of purified ICln protein to the extracellular solution or overexpression of farnesylated ICln leads to an increased anion permeability in NIH 3T3 fibroblasts. The swelling-induced redistribution of ICln correlates to altered kinetics of RVDC in NIH 3T3 fibroblasts, LLC-PK1 cells, and MDCK cells. In these cells, RVDC develops more rapidly, and in MDCK cells the rate of swelling-induced depolarization is accelerated if cells are swollen for a second time. This coincides with an enhanced ICln association with the cell membrane.
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Affiliation(s)
- Markus Ritter
- Department of Physiology, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria.
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Jentsch TJ, Stein V, Weinreich F, Zdebik AA. Molecular structure and physiological function of chloride channels. Physiol Rev 2002; 82:503-68. [PMID: 11917096 DOI: 10.1152/physrev.00029.2001] [Citation(s) in RCA: 934] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cl- channels reside both in the plasma membrane and in intracellular organelles. Their functions range from ion homeostasis to cell volume regulation, transepithelial transport, and regulation of electrical excitability. Their physiological roles are impressively illustrated by various inherited diseases and knock-out mouse models. Thus the loss of distinct Cl- channels leads to an impairment of transepithelial transport in cystic fibrosis and Bartter's syndrome, to increased muscle excitability in myotonia congenita, to reduced endosomal acidification and impaired endocytosis in Dent's disease, and to impaired extracellular acidification by osteoclasts and osteopetrosis. The disruption of several Cl- channels in mice results in blindness. Several classes of Cl- channels have not yet been identified at the molecular level. Three molecularly distinct Cl- channel families (CLC, CFTR, and ligand-gated GABA and glycine receptors) are well established. Mutagenesis and functional studies have yielded considerable insights into their structure and function. Recently, the detailed structure of bacterial CLC proteins was determined by X-ray analysis of three-dimensional crystals. Nonetheless, they are less well understood than cation channels and show remarkably different biophysical and structural properties. Other gene families (CLIC or CLCA) were also reported to encode Cl- channels but are less well characterized. This review focuses on molecularly identified Cl- channels and their physiological roles.
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Affiliation(s)
- Thomas J Jentsch
- Zentrum für Molekulare Neurobiologie Hamburg, Universität Hamburg, Hamburg, Germany.
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Pierce SK, Warren JW. The Taurine Efflux Portal Used to Regulate Cell Volume in Response to Hypoosmotic Stress Seems to Be Similar in Many Cell Types: Lessons to Be Learned from Molluscan Red Blood Cells1. ACTA ACUST UNITED AC 2001. [DOI: 10.1668/0003-1569(2001)041[0710:tteput]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Wang L, Chen L, Jacob TJ. The role of ClC-3 in volume-activated chloride currents and volume regulation in bovine epithelial cells demonstrated by antisense inhibition. J Physiol 2000; 524 Pt 1:63-75. [PMID: 10747184 PMCID: PMC2269844 DOI: 10.1111/j.1469-7793.2000.t01-1-00063.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
1. A chloride current with mild outward rectification was induced in the native bovine non-pigmented ciliary epithelial (NPCE) cells by a 23 % hypotonic solution. The current showed no or little inactivation at depolarized steps. 2. ATP blocked 88 and 61 % of the outward and inward components of the volume-activated chloride current (ICl,vol) with an IC50 of 5.3 and 9.6 mM, respectively. 3. The volume-activated chloride current was decreased and the activation of the current was delayed by inhibiting endogenous ClC-3 expression using a ClC-3 antisense oligonucleotide. The inhibition of the current as a function of antisense concentration was asymptotic with a maximum about 60 %. The remaining current was probably not derived from ClC-3 and was inhibited by ATP. 4. ClC-3 expression in the bovine NPCE cells was verified by immunofluorescence studies. ClC-3 immunofluorescence was distributed throughout the cells but with the predominant location within the nucleus. The expression of ClC-3 protein was diminished by the ClC-3 antisense oligonucleotide with the greatest diminution occurring in the nuclear region. 5. The size of the volume-activated chloride current was positively correlated with the ClC-3 immunofluorescence level. 6. Regulatory volume decrease of the NPCE cells was reduced by ClC-3 antisense oligonucleotide. 7. We conclude that endogenous ClC-3 is associated with the volume-activated chloride current and is involved in cell volume regulation, but that it can only contribute towards a proportion of the current in NPCE cells. 8. The nuclear predominance of ClC-3 immunofluorescence in NPCE cells, the absence of basal activity of chloride current and the marked pharmacological differences between IClC-3 and ICl,vol argue against ClC-3 being the only, or even the main, volume-activated chloride channel in NPCE cells.
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Affiliation(s)
- L Wang
- School of Biosciences, Cardiff University, Cardiff CF1 3US, UK
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14
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Chen L, Wang L, Jacob TJ. Association of intrinsic pICln with volume-activated Cl- current and volume regulation in a native epithelial cell. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C182-92. [PMID: 9886934 DOI: 10.1152/ajpcell.1999.276.1.c182] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the relationship between pICln, the volume-activated Cl- current, and volume regulation in native bovine nonpigmented ciliary epithelial (NPCE) cells. Immunofluorescence studies demonstrated the presence of pICln protein in the NPCE cells. Exposure to hypotonic solution activated a Cl- current and induced regulatory volume decrease (RVD) in freshly isolated bovine NPCE cells. Three antisense oligonucleotides complementary to human pICln mRNA were used in the experiments. The antisense oligonucleotides were taken up by the cells in a dose-dependent manner. The antisense oligonucleotides, designed to be complementary to the initiation codon region of the human pICln mRNA, "knocked down" the pICln protein immunofluorescence, delayed the activation of volume-activated Cl- current, diminished the value of the current, and reduced the ability of the cells to volume regulate. We conclude that pICln is involved in the activation pathway of the volume-activated Cl- current and RVD following hypotonic swelling.
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Affiliation(s)
- L Chen
- School of Biosciences, Cardiff University, Cardiff CF1 3US, United Kingdom
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The 30-kD Domain of Protein 4.1 Mediates Its Binding to the Carboxyl Terminus of pICln, a Protein Involved in Cellular Volume Regulation. Blood 1998. [DOI: 10.1182/blood.v92.4.1442.416k14_1442_1447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythrocyte protein 4.1 (P4.1) is an 80-kD cytoskeletal protein that is important for the maintenance of the structural integrity and flexibility of the red blood cell membrane. Limited chymotryptic digestion of erythroid P4.1 yields 4 structural domains corresponding to the 30-, 16-, 10-, and 22/24-kD domains. Using a yeast two-hybrid system, we isolated cDNA clones encoding pICln that specifically interacts with the 30-kD domain of P4.1. In this report, we show that the carboxyl-terminus (amino acid residues 103-237) of pICln binds to the 30-kD domain of P4.1 in a yeast two-hybrid system. The direct association between the 30-kD domain of P4.1 and pICln was further confirmed by the following findings: (1) the S35-methione–labeled pICln specifically bound to both GST/P4.1-80 (80 kD) and GST/P4.1-30 (30 kD) fusion proteins, but not to the proteins that lack the 30-kD domain; (2) coimmunoprecipitation analysis of the cell extracts from transfected SiHa cells showed that pICln and P4.1 associate in transfected cells. It was reported that pICln can form a complex with actin and may play a role involved in cellular volume regulation. The direct association between P4.1 and pICln suggests that pICln may link P4.1-bound cytoskeletal elements to an unidentified volume-sensitive chloride channel.© 1998 by The American Society of Hematology.
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The 30-kD Domain of Protein 4.1 Mediates Its Binding to the Carboxyl Terminus of pICln, a Protein Involved in Cellular Volume Regulation. Blood 1998. [DOI: 10.1182/blood.v92.4.1442] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractErythrocyte protein 4.1 (P4.1) is an 80-kD cytoskeletal protein that is important for the maintenance of the structural integrity and flexibility of the red blood cell membrane. Limited chymotryptic digestion of erythroid P4.1 yields 4 structural domains corresponding to the 30-, 16-, 10-, and 22/24-kD domains. Using a yeast two-hybrid system, we isolated cDNA clones encoding pICln that specifically interacts with the 30-kD domain of P4.1. In this report, we show that the carboxyl-terminus (amino acid residues 103-237) of pICln binds to the 30-kD domain of P4.1 in a yeast two-hybrid system. The direct association between the 30-kD domain of P4.1 and pICln was further confirmed by the following findings: (1) the S35-methione–labeled pICln specifically bound to both GST/P4.1-80 (80 kD) and GST/P4.1-30 (30 kD) fusion proteins, but not to the proteins that lack the 30-kD domain; (2) coimmunoprecipitation analysis of the cell extracts from transfected SiHa cells showed that pICln and P4.1 associate in transfected cells. It was reported that pICln can form a complex with actin and may play a role involved in cellular volume regulation. The direct association between P4.1 and pICln suggests that pICln may link P4.1-bound cytoskeletal elements to an unidentified volume-sensitive chloride channel.© 1998 by The American Society of Hematology.
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Emma F, Breton S, Morrison R, Wright S, Strange K. Effect of cell swelling on membrane and cytoplasmic distribution of pICln. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:C1545-51. [PMID: 9696697 DOI: 10.1152/ajpcell.1998.274.6.c1545] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
pICln is found ubiquitously in mammalian cells and is postulated to play a critical role in cell volume regulation. Mutagenesis studies led to the proposal that pICln is a swelling-activated anion channel. However, recent studies in Madin-Darby canine kidney cells and endothelial cells have shown that the protein is localized primarily to the cytoplasm. It has therefore been postulated that activation involves reversible translocation of pICln from the cytoplasm and insertion into the plasma membrane. We tested this hypothesis using several different approaches. Fractionation of C6 glioma cells into plasma membrane- and cytoplasm-containing fractions demonstrated that approximately 90% of the recovered pICln was confined to the cytosol. Swelling had no effect on the relative amount of protein present in the plasma membrane fraction. Immunofluorescence microscopy revealed that pICln is localized primarily, if not exclusively, to the cytoplasm of swollen and nonswollen cells. Similarly, transfection of cells with a green fluorescent protein-labeled pICln construct failed to reveal any membrane localization of the protein. These findings do not support the hypothesis that pICln is a volume regulatory anion channel activated by swelling-induced membrane insertion.
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Affiliation(s)
- F Emma
- Renal Division, Children's Hospital, Boston, Massachusetts 02115, USA
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Strange K. Molecular identity of the outwardly rectifying, swelling-activated anion channel: time to reevaluate pICln. J Gen Physiol 1998; 111:617-22. [PMID: 9565399 PMCID: PMC2217135 DOI: 10.1085/jgp.111.5.617] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/1997] [Accepted: 03/16/1998] [Indexed: 11/29/2022] Open
Affiliation(s)
- K Strange
- Laboratory of Cellular and Molecular Physiology, Departments of Anesthesiology and Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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