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Hu Y, Hou Y, Zhou S, Wang Y, Shen C, Mu L, Su D, Zhang R. Mechanism of assembly of snRNP cores assisted by ICln and the SMN complex in fission yeast. iScience 2023; 26:107604. [PMID: 37664592 PMCID: PMC10470402 DOI: 10.1016/j.isci.2023.107604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/11/2023] [Accepted: 08/08/2023] [Indexed: 09/05/2023] Open
Abstract
The spliceosomal snRNP cores, each comprised of a snRNA and a seven-membered Sm ring (D1/D2/F/E/G/D3/B), are assembled by twelve chaperoning proteins in human. However, only six assembly-assisting proteins, ICln and the SMN complex (SMN/Gemin2/Gemin6-8), have been found in Schizosaccharomyces pombe (Sp). Here, we used recombinant proteins to reconstitute the chaperone machinery and investigated the roles of these proteins systematically. We found that, like the human system, the assembly in S. pombe requires ICln and the SMN complex sequentially. However, there are several significant differences. For instance, h_F/E/G forms heterohexamers and heterotrimers, while Sp_F/E/G only forms heterohexamers; h_Gemin2 alone can bind D1/D2/F/E/G, but Sp_Gemin2 cannot. Moreover, we found that Sp_Gemin2 is essential using genetic approaches. These mechanistic studies reveal that these six proteins are necessary and sufficient for Sm core assembly at the molecular level, and enrich our understanding of the chaperone systems in species variation and evolution.
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Affiliation(s)
- Yan Hu
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Yan Hou
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Shijie Zhou
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Yingzhi Wang
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Congcong Shen
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Li Mu
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Dan Su
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
| | - Rundong Zhang
- Department of Ophthalmology, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu 610041, P.R. China
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Mateos JL, Sanchez SE, Legris M, Esteve-Bruna D, Torchio JC, Petrillo E, Goretti D, Blanco-Touriñán N, Seymour DK, Schmid M, Weigel D, Alabadí D, Yanovsky MJ. PICLN modulates alternative splicing and light/temperature responses in plants. PLANT PHYSIOLOGY 2023; 191:1036-1051. [PMID: 36423226 PMCID: PMC9922395 DOI: 10.1093/plphys/kiac527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 10/01/2022] [Indexed: 06/16/2023]
Abstract
Plants undergo transcriptome reprograming to adapt to daily and seasonal fluctuations in light and temperature conditions. While most efforts have focused on the role of master transcription factors, the importance of splicing factors modulating these processes is now emerging. Efficient pre-mRNA splicing depends on proper spliceosome assembly, which in plants and animals requires the methylosome complex. Ion Chloride nucleotide-sensitive protein (PICLN) is part of the methylosome complex in both humans and Arabidopsis (Arabidopsis thaliana), and we show here that the human PICLN ortholog rescues phenotypes of Arabidopsis picln mutants. Altered photomorphogenic and photoperiodic responses in Arabidopsis picln mutants are associated with changes in pre-mRNA splicing that partially overlap with those in PROTEIN ARGININE METHYL TRANSFERASE5 (prmt5) mutants. Mammalian PICLN also acts in concert with the Survival Motor Neuron (SMN) complex component GEMIN2 to modulate the late steps of UsnRNP assembly, and many alternative splicing events regulated by PICLN but not PRMT5, the main protein of the methylosome, are controlled by Arabidopsis GEMIN2. As with GEMIN2 and SM PROTEIN E1/PORCUPINE (SME1/PCP), low temperature, which increases PICLN expression, aggravates morphological and molecular defects of picln mutants. Taken together, these results establish a key role for PICLN in the regulation of pre-mRNA splicing and in mediating plant adaptation to daily and seasonal fluctuations in environmental conditions.
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Affiliation(s)
- Julieta L Mateos
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1405BWE, Argentina
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
- RNA Biology and Molecular Physiology, Faculty of Biology, Bielefeld University, Biele-feld 33615, Germany
| | - Sabrina E Sanchez
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1405BWE, Argentina
| | - Martina Legris
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1405BWE, Argentina
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen 72076, Germany
| | - David Esteve-Bruna
- Instituto de Biología Molecular y Celular de Plantas (CSIC-Universidad Politecnica de Valencia), Valencia 46022, Spain
| | - Jeanette C Torchio
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1405BWE, Argentina
| | - Ezequiel Petrillo
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
| | - Daniela Goretti
- Department of Plant Physiology, Umea Plant Science Centre, Umea University, Umea SE-901 87, Sweden
| | - Noel Blanco-Touriñán
- Instituto de Biología Molecular y Celular de Plantas (CSIC-Universidad Politecnica de Valencia), Valencia 46022, Spain
| | - Danelle K Seymour
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen 72076, Germany
| | - Markus Schmid
- Department of Plant Physiology, Umea Plant Science Centre, Umea University, Umea SE-901 87, Sweden
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen 72076, Germany
| | - David Alabadí
- Instituto de Biología Molecular y Celular de Plantas (CSIC-Universidad Politecnica de Valencia), Valencia 46022, Spain
| | - Marcelo J Yanovsky
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1405BWE, Argentina
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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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Prusty AB, Meduri R, Prusty BK, Vanselow J, Schlosser A, Fischer U. Impaired spliceosomal UsnRNP assembly leads to Sm mRNA down-regulation and Sm protein degradation. J Cell Biol 2017. [PMID: 28637748 PMCID: PMC5551706 DOI: 10.1083/jcb.201611108] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cellular spliceosomal UsnRNP assembly is assisted by the PRMT5 and SMN complexes. Prusty et al. demonstrate that perturbations in the assembly machinery of UsnRNPs trigger complex cellular responses, using ribosomes, exosome-mediated RNA degradation, and autophagy to prevent Sm protein aggregation. Specialized assembly factors facilitate the formation of many macromolecular complexes in vivo. The formation of Sm core structures of spliceosomal U-rich small nuclear ribonucleoprotein particles (UsnRNPs) requires assembly factors united in protein arginine methyltransferase 5 (PRMT5) and survival motor neuron (SMN) complexes. We demonstrate that perturbations of this assembly machinery trigger complex cellular responses that prevent aggregation of unassembled Sm proteins. Inactivation of the SMN complex results in the initial tailback of Sm proteins on the PRMT5 complex, followed by down-regulation of their encoding mRNAs. In contrast, reduction of pICln, a PRMT5 complex subunit, leads to the retention of newly synthesized Sm proteins on ribosomes and their subsequent lysosomal degradation. Overexpression of Sm proteins under these conditions results in a surplus of Sm proteins over pICln, promoting their aggregation. Our studies identify an elaborate safeguarding system that prevents individual Sm proteins from aggregating, contributing to cellular UsnRNP homeostasis.
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Affiliation(s)
| | - Rajyalakshmi Meduri
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Bhupesh Kumar Prusty
- Department of Microbiology, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Jens Vanselow
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Utz Fischer
- Department of Biochemistry, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany .,Department of Radiation Medicine and Applied Sciences, University of California at San Diego, San Diego, CA
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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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Borg RM, Fenech Salerno B, Vassallo N, Bordonne R, Cauchi RJ. Disruption of snRNP biogenesis factors Tgs1 and pICln induces phenotypes that mirror aspects of SMN-Gemins complex perturbation in Drosophila, providing new insights into spinal muscular atrophy. Neurobiol Dis 2016; 94:245-58. [PMID: 27388936 DOI: 10.1016/j.nbd.2016.06.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 06/20/2016] [Accepted: 06/27/2016] [Indexed: 01/27/2023] Open
Abstract
The neuromuscular disorder, spinal muscular atrophy (SMA), results from insufficient levels of the survival motor neuron (SMN) protein. Together with Gemins 2-8 and Unrip, SMN forms the large macromolecular SMN-Gemins complex, which is known to be indispensable for chaperoning the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). It remains unclear whether disruption of this function is responsible for the selective neuromuscular degeneration in SMA. In the present study, we first show that loss of wmd, the Drosophila Unrip orthologue, has a negative impact on the motor system. However, due to lack of a functional relationship between wmd/Unrip and Gemin3, it is likely that Unrip joined the SMN-Gemins complex only recently in evolution. Second, we uncover that disruption of either Tgs1 or pICln, two cardinal players in snRNP biogenesis, results in viability and motor phenotypes that closely resemble those previously uncovered on loss of the constituent members of the SMN-Gemins complex. Interestingly, overexpression of both factors leads to motor dysfunction in Drosophila, a situation analogous to that of Gemin2. Toxicity is conserved in the yeast S. pombe where pICln overexpression induces a surplus of Sm proteins in the cytoplasm, indicating that a block in snRNP biogenesis is partly responsible for this phenotype. Importantly, we show a strong functional relationship and a physical interaction between Gemin3 and either Tgs1 or pICln. We propose that snRNP biogenesis is the pathway connecting the SMN-Gemins complex to a functional neuromuscular system, and its disturbance most likely leads to the motor dysfunction that is typical in SMA.
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Affiliation(s)
- Rebecca M Borg
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta; Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Université Montpellier 1 and 2, Montpellier, France
| | - Benji Fenech Salerno
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Neville Vassallo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Rémy Bordonne
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Université Montpellier 1 and 2, Montpellier, France
| | - Ruben J Cauchi
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta.
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Pedersen SF, Okada Y, Nilius B. Biophysics and Physiology of the Volume-Regulated Anion Channel (VRAC)/Volume-Sensitive Outwardly Rectifying Anion Channel (VSOR). Pflugers Arch 2016; 468:371-83. [DOI: 10.1007/s00424-015-1781-6] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 12/19/2015] [Accepted: 12/21/2015] [Indexed: 01/25/2023]
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8
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Pedersen SF, Klausen TK, Nilius B. The identification of a volume-regulated anion channel: an amazing Odyssey. Acta Physiol (Oxf) 2015; 213:868-81. [PMID: 25565132 DOI: 10.1111/apha.12450] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/05/2014] [Accepted: 01/05/2015] [Indexed: 01/03/2023]
Abstract
The volume-regulated anion channel (VRAC) plays a pivotal role in cell volume regulation in essentially all cell types studied. Additionally, VRAC appears to contribute importantly to a wide range of other cellular functions and pathological events, including cell motility, cell proliferation, apoptosis and excitotoxic glutamate release in stroke. Although biophysically, pharmacologically and functionally thoroughly described, VRAC has until very recently remained a genetic orphan. The search for the molecular identity of VRAC has been long and has yielded multiple potential candidates, all of which eventually turned out to have properties not fully compatible with those of VRAC. Recently, two groups have independently identified the protein leucine-rich repeats containing 8A (LRRC8A), belonging to family of proteins (LRRC8A-E) distantly related to pannexins, as the likely pore-forming subunit of VRAC. In this brief review, we summarize the history of the discovery of VRAC, outline its basic biophysical and pharmacological properties, link these to several cellular functions in which VRAC appears to play important roles, and sketch the amazing search for the molecular identity of this channel. Finally, we describe properties of the LRRC8 proteins, highlight some features of the LRRC8A knockout mouse and discuss the impact of the discovery of LRRC8 as VRAC on future research.
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Affiliation(s)
- S. F. Pedersen
- Section for Cell and Developmental Biology; Department of Biology; Faculty of Science; University of Copenhagen; Copenhagen Denmark
| | - T. K. Klausen
- Section for Cell and Developmental Biology; Department of Biology; Faculty of Science; University of Copenhagen; Copenhagen Denmark
| | - B. Nilius
- Laboratory of Ion Channel Research; Department of Cellular and Molecular Medicine; KU Leuven, Campus Gasthuisberg; Leuven Belgium
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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: 4] [Impact Index Per Article: 0.4] [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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10
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Characterization and in vivo functional analysis of the Schizosaccharomyces pombe ICLN gene. Mol Cell Biol 2013; 34:595-605. [PMID: 24298023 DOI: 10.1128/mcb.01407-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the early steps of snRNP biogenesis, the survival motor neuron (SMN) complex acts together with the methylosome, an entity formed by the pICln protein, WD45, and the PRMT5 methyltransferase. To expand our understanding of the functional relationship between pICln and SMN in vivo, we performed a genetic analysis of an uncharacterized Schizosaccharomyces pombe pICln homolog. Although not essential, the S. pombe ICln (SpICln) protein is important for optimal yeast cell growth. The human ICLN gene complements the Δicln slow-growth phenotype, demonstrating that the identified SpICln sequence is the bona fide human homolog. Consistent with the role of human pICln inferred from in vitro experiments, we found that the SpICln protein is required for optimal production of the spliceosomal snRNPs and for efficient splicing in vivo. Genetic interaction approaches further demonstrate that modulation of ICln activity is unable to compensate for growth defects of SMN-deficient cells. Using a genome-wide approach and reverse transcription (RT)-PCR validation tests, we also show that splicing is differentially altered in Δicln cells. Our data are consistent with the notion that splice site selection and spliceosome kinetics are highly dependent on the concentration of core spliceosomal components.
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11
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Lewis R, May H, Mobasheri A, Barrett-Jolley R. Chondrocyte channel transcriptomics: do microarray data fit with expression and functional data? Channels (Austin) 2013; 7:459-67. [PMID: 23995703 PMCID: PMC4042480 DOI: 10.4161/chan.26071] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To date, a range of ion channels have been identified in chondrocytes using a number of different techniques, predominantly electrophysiological and/or biomolecular; each of these has its advantages and disadvantages. Here we aim to compare and contrast the data available from biophysical and microarray experiments. This letter analyses recent transcriptomics datasets from chondrocytes, accessible from the European Bioinformatics Institute (EBI). We discuss whether such bioinformatic analysis of microarray datasets can potentially accelerate identification and discovery of ion channels in chondrocytes. The ion channels which appear most frequently across these microarray datasets are discussed, along with their possible functions. We discuss whether functional or protein data exist which support the microarray data. A microarray experiment comparing gene expression in osteoarthritis and healthy cartilage is also discussed and we verify the differential expression of 2 of these genes, namely the genes encoding large calcium-activated potassium (BK) and aquaporin channels.
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Affiliation(s)
- Rebecca Lewis
- Musculoskeletal Biology; Institute of Ageing and Chronic Disease; Faculty of Health & Life Sciences; University of Liverpool; Liverpool, UK; The D-BOARD European Consortium for Biomarker Discovery
| | - Hannah May
- Musculoskeletal Biology; Institute of Ageing and Chronic Disease; Faculty of Health & Life Sciences; University of Liverpool; Liverpool, UK
| | - Ali Mobasheri
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis; Arthritis Research UK Pain Centre; Medical Research Council and Arthritis Research UK Centre for Musculoskeletal Ageing Research; The University of Nottingham; Queen's Medical Centre; Nottingham, UK; School of Life Sciences; University of Bradford; Bradford, UK; Center for Excellence in Genomic Medicine Research (CEGMR); King Fahad Medical Research Center (KFMRC); King AbdulAziz University; Jeddah, Saudi Arabia; The D-BOARD European Consortium for Biomarker Discovery
| | - Richard Barrett-Jolley
- Musculoskeletal Biology; Institute of Ageing and Chronic Disease; Faculty of Health & Life Sciences; University of Liverpool; Liverpool, UK; The D-BOARD European Consortium for Biomarker Discovery
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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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13
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Pesiridis GS, Diamond E, Van Duyne GD. Role of pICLn in methylation of Sm proteins by PRMT5. J Biol Chem 2009; 284:21347-59. [PMID: 19520849 PMCID: PMC2755859 DOI: 10.1074/jbc.m109.015578] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 06/10/2009] [Indexed: 11/25/2022] Open
Abstract
pICln is an essential, highly conserved 26-kDa protein whose functions include binding to Sm proteins in the cytoplasm of human cells and mediating the ordered and regulated assembly of the cell's RNA-splicing machinery by the survival motor neurons complex. pICln also interacts with PRMT5, the enzyme responsible for generating symmetric dimethylarginine modifications on the carboxyl-terminal regions of three of the canonical Sm proteins. To better understand the role of pICln in these cellular processes, we have investigated the properties of pICln and pICln.Sm complexes and the effects that pICln has on the methyltransferase activity of PRMT5. We find that pICln is a monomer in solution, binds with high affinity (K(d) approximately 160 nm) to SmD3-SmB, and forms 1:1 complexes with Sm proteins and Sm protein subcomplexes. The data support an end-capping model of pICln binding that supports current views of how pICln prevents Sm oligomerization on illicit RNA substrates. We have found that by co-expression with pICln, recombinant PRMT5 can be produced in a soluble, active form. PRMT5 alone has promiscuous activity toward a variety of known substrates. In the presence of pICln, however, PRMT5 methylation of Sm proteins is stimulated, but methylation of histones is inhibited. We have also found that mutations in pICln that do not affect Sm protein binding can still have a profound effect on the methyltransferase activity of the PRMT5 complex. Together, the data provide insights into pICln function and represent an important starting point for biochemical analyses of PRMT5.
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Affiliation(s)
- G. Scott Pesiridis
- From the Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Evan Diamond
- From the Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Gregory D. Van Duyne
- From the Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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14
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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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15
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Abstract
Cl(-) channels are widely found anion pores that are regulated by a variety of signals and that play various roles. On the basis of molecular biologic findings, ligand-gated Cl(-) channels in synapses, cystic fibrosis transmembrane conductors (CFTRs) and ClC channel types have been established, followed by bestrophin and possibly by tweety, which encode Ca(2+)-activated Cl(-) channels. The ClC family has been shown to possess a variety of functions, including stabilization of membrane potential, excitation, cell-volume regulation, fluid transport, protein degradation in endosomal vesicles and possibly cell growth. The molecular structure of Cl(-) channel types varies from 1 to 12 transmembrane segments. By means of computer-based prediction, functional Cl(-) channels have been synthesized artificially, revealing that many possible ion pores are hidden in channel, transporter or unidentified hydrophobic membrane proteins. Thus, novel Cl(-)-conducting pores may be occasionally discovered, and evidence from molecular biologic studies will clarify their physiologic and pathophysiologic roles.
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Affiliation(s)
- M Suzuki
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical School, Tochigi 329-0498, Japan.
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16
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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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17
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Jiang W, Roemer ME, Newsham IF. The tumor suppressor DAL-1/4.1B modulates protein arginine N-methyltransferase 5 activity in a substrate-specific manner. Biochem Biophys Res Commun 2005; 329:522-30. [PMID: 15737618 DOI: 10.1016/j.bbrc.2005.01.153] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Indexed: 11/18/2022]
Abstract
We previously identified DAL-1/4.1B as a growth suppression protein involved in the pathogenesis of lung, breast, and meningioma tumors. Using yeast two-hybrid interaction cloning, protein arginine N-methyltransferase 3 (PRMT3) was originally identified as a DAL-1/4.1B-interacting protein. PRMTs catalyze the sequential transfer of methyl groups from S-adeonsyl-l-methionine to the guanidino nitrogens of arginine residues in proteins, the effect of which can include regulation of signal transduction, transcription regulation, and RNA transport, suggesting that modulating this event may have far-reaching impact. In this study, we assessed the impact of DAL-1/4.1B binding on the activity of another family member, PRMT5, both in vitro and in cells. In contrast to PRMT3, DAL-1/4.1B was found to mediate PRMT5 by either inhibiting (Sm proteins) or enhancing (myelin basic protein) protein methylation. We propose that this interaction between a tumor suppressor and a post-translational methylation enzyme is of biological importance in controlling tumorigenesis.
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Affiliation(s)
- Wei Jiang
- David and Doreen Hermelin Laboratory of Molecular Oncogenetics, Department of Neurosurgery, Hermelin Brain Tumor Center, Henry Ford Hospital, Detroit, MI 48202, USA
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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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Abstract
AIM This review describes molecular and functional properties of the following Cl- channels: the ClC family of voltage-dependent Cl- channels, the cAMP-activated transmembrane conductance regulator (CFTR), Ca2+ activated Cl- channels (CaCC) and volume-regulated anion channels (VRAC). If structural data are available, their relationship with the function of Cl- channels will be discussed. We also describe shortly some recently discovered channels, including high conductance Cl- channels and the family of bestrophins. We illustrate the growing physiological importance of these channels in the plasma membrane and in intracellular membranes, including their involvement in transepithelial transport, pH regulation of intracellular organelles, regulation of excitability and volume regulation. Finally, we discuss the role of Cl- channels in various diseases and describe the pathological phenotypes observed in knockout mice models.
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Affiliation(s)
- B Nilius
- KU Leuven, Laboratorium voor Fysiologie, Campus Gasthuisberg, Leuven, Belgium
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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: 941] [Impact Index Per Article: 42.8] [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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