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Manori B, Vaknin A, Vaňková P, Nitzan A, Zaidel-Bar R, Man P, Giladi M, Haitin Y. Chloride intracellular channel (CLIC) proteins function as fusogens. Nat Commun 2024; 15:2085. [PMID: 38453905 PMCID: PMC10920813 DOI: 10.1038/s41467-024-46301-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 02/19/2024] [Indexed: 03/09/2024] Open
Abstract
Chloride Intracellular Channel (CLIC) family members uniquely transition between soluble and membrane-associated conformations. Despite decades of extensive functional and structural studies, CLICs' function as ion channels remains debated, rendering our understanding of their physiological role incomplete. Here, we expose the function of CLIC5 as a fusogen. We demonstrate that purified CLIC5 directly interacts with the membrane and induces fusion, as reflected by increased liposomal diameter and lipid and content mixing between liposomes. Moreover, we show that this activity is facilitated by acidic pH, a known trigger for CLICs' transition to a membrane-associated conformation, and that increased exposure of the hydrophobic inter-domain interface is crucial for this process. Finally, mutation of a conserved hydrophobic interfacial residue diminishes the fusogenic activity of CLIC5 in vitro and impairs excretory canal extension in C. elegans in vivo. Together, our results unravel the long-sought physiological role of these enigmatic proteins.
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Grants
- 1721/16 Israel Science Foundation (ISF)
- 1653/21 Israel Science Foundation (ISF)
- 3308/20 Israel Science Foundation (ISF)
- 01214 Israel Cancer Research Fund (Israel Cancer Research Fund, Inc.)
- 19202 Israel Cancer Research Fund (Israel Cancer Research Fund, Inc.)
- 20230029 Israel Cancer Association (ICA)
- CZ.1.05/1.1.00/02.0109 Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky (Ministry of Education, Science, Research and Sport of the Slovak Republic)
- 731077 EC | Horizon 2020 Framework Programme (EU Framework Programme for Research and Innovation H2020)
- The Claire and Amedee Maratier Institute for the Study of Blindness and Visual Disorders, Faculty of Medicine, Tel-Aviv University.
- The Czech Infrastructure for Integrative Structural Biology (CIISB) grant (LM2023042).
- The Kahn Foundation's Orion project, Tel Aviv Sourasky Medical Center, Israel. The Claire and Amedee Maratier Institute for the Study of Blindness and Visual Disorders, Faculty of Medicine, Tel-Aviv University.
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Affiliation(s)
- Bar Manori
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Alisa Vaknin
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Pavla Vaňková
- Institute of Biotechnology of the Czech Academy of Sciences, Division BioCeV, Prumyslova 595, 252 50, Vestec, Czech Republic
| | - Anat Nitzan
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Petr Man
- Institute of Microbiology of the Czech Academy of Sciences, Division BioCeV, Prumyslova 595, 252 50, Vestec, Czech Republic
| | - Moshe Giladi
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel.
- Tel Aviv Sourasky Medical Center, Tel Aviv, 6423906, Israel.
| | - Yoni Haitin
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel.
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel.
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2
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Kleinjan ML, Mao DY, Naiche LA, Joshi JC, Gupta A, Jesse JJ, Shaye DD, Mehta D, Kitajewski J. CLIC4 Regulates Endothelial Barrier Control by Mediating PAR1 Signaling via RhoA. Arterioscler Thromb Vasc Biol 2023; 43:1441-1454. [PMID: 37317855 PMCID: PMC10527476 DOI: 10.1161/atvbaha.123.319206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 05/30/2023] [Indexed: 06/16/2023]
Abstract
BACKGROUND Endothelial CLICs (chloride intracellular channel proteins) CLIC1 and CLIC4 are required for the GPCRs (G-protein-coupled receptors) S1PR1 (sphingosine-1-phosphate receptor 1) and S1PR3 to activate the small GTPases Rac1 (Ras-related C3 botulinum toxin substrate 1) and RhoA (Ras homolog family member A). To determine whether CLIC1 and CLIC4 function in additional endothelial GPCR pathways, we evaluated CLIC function in thrombin signaling via the thrombin-regulated PAR1 (protease-activated receptor 1) and downstream effector RhoA. METHODS We assessed the ability of CLIC1 and CLIC4 to relocalize to cell membranes in response to thrombin in human umbilical vein endothelial cells (HUVEC). We examined CLIC1 and CLIC4 function in HUVEC by knocking down expression of each CLIC protein and compared thrombin-mediated RhoA or Rac1 activation, ERM (ezrin/radixin/moesin) phosphorylation, and endothelial barrier modulation in control and CLIC knockdown HUVEC. We generated a conditional murine allele of Clic4 and examined PAR1-mediated lung microvascular permeability and retinal angiogenesis in mice with endothelial-specific loss of Clic4. RESULTS Thrombin promoted relocalization of CLIC4, but not CLIC1, to HUVEC membranes. Knockdown of CLIC4 in HUVEC reduced thrombin-mediated RhoA activation, ERM phosphorylation, and endothelial barrier disruption. Knockdown of CLIC1 did not reduce thrombin-mediated RhoA activity but prolonged the RhoA and endothelial barrier response to thrombin. Endothelial-specific deletion of Clic4 in mice reduced lung edema and microvascular permeability induced by PAR1 activating peptide. CONCLUSIONS CLIC4 is a critical effector of endothelial PAR1 signaling and is required to regulate RhoA-mediated endothelial barrier disruption in cultured endothelial cells and murine lung endothelium. CLIC1 was not critical for thrombin-mediated barrier disruption but contributed to the barrier recovery phase after thrombin treatment.
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Affiliation(s)
- Matthew L. Kleinjan
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - De Yu Mao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - L. A. Naiche
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Jagdish C. Joshi
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA
| | - Ahana Gupta
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Jordan J. Jesse
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Daniel D. Shaye
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Dolly Mehta
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA
| | - Jan Kitajewski
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
- University of Illinois Cancer Center, Chicago, IL, USA
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3
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Dosch J, Bergmann H, Tran V, Ebersberger I. FAS: assessing the similarity between proteins using multi-layered feature architectures. Bioinformatics 2023; 39:btad226. [PMID: 37084276 PMCID: PMC10185405 DOI: 10.1093/bioinformatics/btad226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/23/2023] [Accepted: 04/13/2023] [Indexed: 04/23/2023] Open
Abstract
MOTIVATION Protein sequence comparison is a fundamental element in the bioinformatics toolkit. When sequences are annotated with features such as functional domains, transmembrane domains, low complexity regions or secondary structure elements, the resulting feature architectures allow better informed comparisons. However, many existing schemes for scoring architecture similarities cannot cope with features arising from multiple annotation sources. Those that do fall short in the resolution of overlapping and redundant feature annotations. RESULTS Here, we introduce FAS, a scoring method that integrates features from multiple annotation sources in a directed acyclic architecture graph. Redundancies are resolved as part of the architecture comparison by finding the paths through the graphs that maximize the pair-wise architecture similarity. In a large-scale evaluation on more than 10 000 human-yeast ortholog pairs, architecture similarities assessed with FAS are consistently more plausible than those obtained using e-values to resolve overlaps or leaving overlaps unresolved. Three case studies demonstrate the utility of FAS on architecture comparison tasks: benchmarking of orthology assignment software, identification of functionally diverged orthologs, and diagnosing protein architecture changes stemming from faulty gene predictions. With the help of FAS, feature architecture comparisons can now be routinely integrated into these and many other applications. AVAILABILITY AND IMPLEMENTATION FAS is available as python package: https://pypi.org/project/greedyFAS/.
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Affiliation(s)
- Julian Dosch
- Applied Bioinformatics Group, Goethe University Frankfurt, Faculty of Biosciences, Institute of Cell Biology and Neuroscience, Frankfurt, 60438, Germany
| | - Holger Bergmann
- Applied Bioinformatics Group, Goethe University Frankfurt, Faculty of Biosciences, Institute of Cell Biology and Neuroscience, Frankfurt, 60438, Germany
| | - Vinh Tran
- Applied Bioinformatics Group, Goethe University Frankfurt, Faculty of Biosciences, Institute of Cell Biology and Neuroscience, Frankfurt, 60438, Germany
| | - Ingo Ebersberger
- Applied Bioinformatics Group, Goethe University Frankfurt, Faculty of Biosciences, Institute of Cell Biology and Neuroscience, Frankfurt, 60438, Germany
- Senckenberg Biodiversity and Climate Research Centre (S-BIKF), Frankfurt, 60325, Germany
- LOEWE Centre for Translational Biodiversity Genomics (TBG), Frankfurt, 60325, Germany
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4
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Structure-based discovery and in vitro validation of inhibitors of chloride intracellular channel 4 protein. Comput Struct Biotechnol J 2022; 21:688-701. [PMID: 36659928 PMCID: PMC9826898 DOI: 10.1016/j.csbj.2022.12.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 12/25/2022] Open
Abstract
The use of computer-aided methods have continued to propel accelerated drug discovery across various disease models, interestingly allowing the specific inhibition of pathogenic targets. Chloride Intracellular Channel Protein 4 (CLIC4) is a novel class of intracellular ion channel highly implicated in tumor and vascular biology. It regulates cell proliferation, apoptosis and angiogenesis; and is involved in multiple pathologic signaling pathways. Absence of specific inhibitors however impedes its advancement to translational research. Here, we integrate structural bioinformatics and experimental research approaches for the discovery and validation of small-molecule inhibitors of CLIC4. High-affinity allosteric binders were identified from a library of 1615 Food and Drug Administration (FDA)-approved drugs via a high-performance computing-powered blind-docking approach, resulting in the selection of amphotericin B and rapamycin. NMR assays confirmed the binding and conformational disruptive effects of both drugs while they also reversed stress-induced membrane translocation of CLIC4 and inhibited endothelial cell migration. Structural and dynamics simulation studies further revealed that the inhibitory mechanisms of these compounds were hinged on the allosteric modulation of the catalytic glutathione (GSH)-like site loop and the extended catalytic β loop which may elicit interference with the catalytic activities of CLIC4. Structure-based insights from this study provide the basis for the selective targeting of CLIC4 to treat the associated pathologies.
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Key Words
- A9C, 9-Anthracenecarboxylic acid
- AMPhB, Amphotericin B
- Ad, Adenovirus
- Allosteric inhibition
- Bad, BCL2 associated agonist of cell death
- Bcl-2, B-cell lymphoma 2
- Bcl-xL, B-cell lymphoma-extra large
- CDK, Cyclin-dependent kinases
- CLIC, Chloride intracellular channel protein
- Chloride intracellular channel protein 4
- Computational high-throughput screening
- DAPI, 4′,6-diamidino-2-phenylindole
- DIDS, 4,4′-Diisothiocyano-2,2′-stilbenedisulfonic acid
- DMSO, Dimethyl sulfoxide
- DOPE, Discrete optimized protein energy
- GPU, Graphics Processing Unit
- GSH-like catalytic site
- GST, glutathione S-transferases
- GUI, Graphical User Interface
- HEPES, (4-(2-hydroxyethyl)− 1-piperazineethanesulfonic acid;
- HIF, Hypoxia-inducible factor
- HSQC, Heteronuclear single quantum coherence spectroscopy
- HUVEC, Human umbilical vein endothelial cells
- IKKβ, Inhibitor of nuclear kappa-B-kinase subunit beta
- JNK, c-Jun N-terminal kinase
- MKK6, Mitogen-activated protein kinase kinase-6
- MOI, Multiplicity of infection
- NF-κB, Nuclear factor kappa-light-chain-enhancer of activated B cells
- NMR, Nuclear magnetic resonance
- NPT, The constant-temperature, constant-pressure ensemble
- NaCL, Sodium chloride
- Nuclear magnetic resonance
- PAH, Pulmonary arterial hypertension
- RAPA, Rapamycin
- SASA, Solvent accessible surface area
- SEK1, Dual specificity mitogen-activated protein kinase kinase 4
- Smad, Suppressor of Mothers against Decapentaplegic
- Structure-based drug discovery
- TEV, Tobacco etch virus
- TIP3P, Transferable intermolecular potential 3 P
- TROSY, Transverse relaxation optimized spectroscopy
- UCSF, University of California, San Francisco
- VEGF, Vascular endothelial growth factor
- p38, Mitogen activated protein kinases
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5
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Arena AF, Escudero J, Shaye DD. A metazoan-specific C-terminal motif in EXC-4 and Gα-Rho/Rac signaling regulate cell outgrowth during tubulogenesis in C. elegans. Development 2022; 149:285944. [PMID: 36398726 PMCID: PMC10108608 DOI: 10.1242/dev.200748] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022]
Abstract
Chloride intracellular channels (CLICs) are conserved proteins for which the cellular and molecular functions remain mysterious. An important insight into CLIC function came from the discovery that Caenorhabditis elegans EXC-4/CLIC regulates morphogenesis of the excretory canal (ExCa) cell, a single-cell tube. Subsequent work showed that mammalian CLICs regulate vascular development and angiogenesis, and human CLIC1 can rescue exc-4 mutants, suggesting conserved function in biological tube formation (tubulogenesis) and maintenance. However, the cell behaviors and signaling pathways regulated by EXC-4/CLICs during tubulogenesis in vivo remain largely unknown. We report a new exc-4 mutation, affecting a C-terminal residue conserved in virtually all metazoan CLICs, that reveals a specific role for EXC-4 in ExCa outgrowth. Cell culture studies suggest a function for CLICs in heterotrimeric G protein (Gα/β/γ)-Rho/Rac signaling, and Rho-family GTPases are common regulators of cell outgrowth. Using our new exc-4 mutant, we describe a previously unknown function for Gα-encoding genes (gpa-12/Gα12/13, gpa-7/Gαi, egl-30/Gαq and gsa-1/Gαs), ced-10/Rac and mig-2/RhoG in EXC-4-mediated ExCa outgrowth. Our results demonstrate that EXC-4/CLICs are primordial players in Gα-Rho/Rac-signaling, a pathway that is crucial for tubulogenesis in C. elegans and in vascular development.
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Affiliation(s)
- Anthony F Arena
- Department of Physiology and Biophysics, University of Illinois at Chicago - College of Medicine, Chicago, IL 60612, USA.,Graduate Education in Biomedical Sciences program, University of Illinois at Chicago - College of Medicine, Chicago, IL 60612, USA
| | - Julianna Escudero
- Department of Physiology and Biophysics, University of Illinois at Chicago - College of Medicine, Chicago, IL 60612, USA
| | - Daniel D Shaye
- Department of Physiology and Biophysics, University of Illinois at Chicago - College of Medicine, Chicago, IL 60612, USA.,Center for Cardiovascular Research, University of Illinois at Chicago - College of Medicine, Chicago, IL 60612, USA
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6
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Chuang JZ, Yang N, Nakajima N, Otsu W, Fu C, Yang HH, Lee MP, Akbar AF, Badea TC, Guo Z, Nuruzzaman A, Hsu KS, Dunaief JL, Sung CH. Retinal pigment epithelium-specific CLIC4 mutant is a mouse model of dry age-related macular degeneration. Nat Commun 2022; 13:374. [PMID: 35042858 PMCID: PMC8766482 DOI: 10.1038/s41467-021-27935-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/21/2021] [Indexed: 12/12/2022] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly. Dry AMD has unclear etiology and no treatment. Lipid-rich drusen are the hallmark of dry AMD. An AMD mouse model and insights into drusenogenesis are keys to better understanding of this disease. Chloride intracellular channel 4 (CLIC4) is a pleomorphic protein regulating diverse biological functions. Here we show that retinal pigment epithelium (RPE)-specific Clic4 knockout mice exhibit a full spectrum of functional and pathological hallmarks of dry AMD. Multidisciplinary longitudinal studies of disease progression in these mice support a mechanistic model that links RPE cell-autonomous aberrant lipid metabolism and transport to drusen formation.
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Affiliation(s)
- Jen-Zen Chuang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
| | - Nan Yang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Nobuyuki Nakajima
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Department of Urology, Tokai University, Kanagawa, Japan
| | - Wataru Otsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Cheng Fu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Howard Hua Yang
- The Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Maxwell Ping Lee
- The Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Tudor Constantin Badea
- National Eye Institute, National institute of Health, Bethesda, MD, USA
- Research and Development Institute, Transilvania University of Brasov, School of Medicine, Brasov, Romania
| | - Ziqi Guo
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Afnan Nuruzzaman
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Kuo-Shun Hsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Sloan Kettering Cancer Institute, New York, NY, USA
| | - Joshua L Dunaief
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ching-Hwa Sung
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
- Department of Cell and Developmental Biology, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
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7
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Arbildi P, La-Rocca S, Kun A, Lorenzatto KR, Monteiro KM, Zaha A, Mourglia-Ettlin G, Ferreira HB, Fernández V. Expression and distribution of glutathione transferases in protoscoleces of Echinococcus granulosus sensu lato. Acta Trop 2021; 221:105991. [PMID: 34089697 DOI: 10.1016/j.actatropica.2021.105991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 05/21/2021] [Accepted: 05/26/2021] [Indexed: 10/21/2022]
Abstract
Glutathione transferases (GSTs) belong to a diverse superfamily of multifunctional proteins involved in metabolic detoxification. In helminth parasite, GSTs are particularly relevant since they are also involved in host immunomodulation. Echinococcus granulosus sensu lato (s.l.) is a cestode parasite known to express at least three phylogenetically distant cytosolic GSTs: EgGST1 and EgGST2 previously grouped within Mu and Sigma classes, respectively; and EgGST3 related to both Omega and Sigma classes. To better characterize E. granulosus s.l. GSTs, herein their expression and distribution were assessed in the pre-adult protoscolex (PSC) parasite stage. Potential transcriptional regulatory mechanisms of the corresponding EgGST genes were also explored. Firstly, the transcription of the three EgGSTs was significantly induced during the early stages of the murine model of infection, suggesting a potential role during parasite establishment. EgGST1 was detected in the parenchyma of PSCs and its expression increased after H2O2 exposure, supporting its role in detoxification. EgGST2 was mainly detected on the PSCs tegument, strategically localized for potential immunoregulation functions due to its Sigma-class characteristics. In addition, its expression increased after anthelmintic treatment, suggesting a role in chemotherapy resistance. Finally, the Omega-related EgGST3 was localized throughout the entire PSC body, including suckers and tegument, and since its expression also increased after H2O2 treatment, a potential role in oxidative stress response could also be ascribed. On the other hand, known cis-acting regulatory motifs were detected in EgGST genes, suggesting similar transcription processes to other eukaryotes. The results herein reported provide additional data regarding the roles of EgGSTs in E. granulosus s.l. biology, contributing to a better understanding of its host-parasite interaction.
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8
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Mao DY, Kleinjan ML, Jilishitz I, Swaminathan B, Obinata H, Komarova YA, Bayless KJ, Hla T, Kitajewski JK. CLIC1 and CLIC4 mediate endothelial S1P receptor signaling to facilitate Rac1 and RhoA activity and function. Sci Signal 2021; 14:14/679/eabc0425. [PMID: 33879602 DOI: 10.1126/scisignal.abc0425] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Chloride intracellular channels 1 (CLIC1) and 4 (CLIC4) are expressed in endothelial cells and regulate angiogenic behaviors in vitro, and the expression of Clic4 is important for vascular development and function in mice. Here, we found that CLIC1 and CLIC4 in endothelial cells regulate critical G protein-coupled receptor (GPCR) pathways associated with vascular development and disease. In cultured endothelial cells, we found that CLIC1 and CLIC4 transiently translocated to the plasma membrane in response to sphingosine 1-phosphate (S1P). Both CLIC1 and CLIC4 were essential for mediating S1P-induced activation of the small guanosine triphosphatase (GTPase) Rac1 downstream of S1P receptor 1 (S1PR1). In contrast, only CLIC1 was essential for S1P-induced activation of the small GTPase RhoA downstream of S1PR2 and S1PR3. Neither were required for other S1P-S1PR signaling outputs. Rescue experiments revealed that CLIC1 and CLIC4 were not functionally interchangeable, suggesting distinct and specific functions for CLICs in transducing GPCR signaling. These CLIC-mediated mechanisms were critical for S1P-induced stimulation of the barrier function in endothelial cell monolayers. Our results define CLICs as previously unknown players in the pathways linking GPCRs to small GTPases and vascular endothelial function.
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Affiliation(s)
- De Yu Mao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew L Kleinjan
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | | | - Bhairavi Swaminathan
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Hideru Obinata
- Education and Research Support Center, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yulia A Komarova
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA
| | - Kayla J Bayless
- Department of Molecular & Cellular Medicine, Texas A&M System Health Science Center, Bryan, TX, USA
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital, Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - Jan K Kitajewski
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA.
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9
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Chen J, Wang F, Lu Y, Yang S, Chen X, Huang Y, Lin X. CLC-3 and SOX2 regulate the cell cycle in DU145 cells. Oncol Lett 2020; 20:372. [PMID: 33154770 PMCID: PMC7608052 DOI: 10.3892/ol.2020.12235] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 07/23/2020] [Indexed: 12/28/2022] Open
Abstract
Sex determining region Y-box 2 (SOX2) is a transcription factor that serves a role in numerous different types of malignant cancer. Altered expression of chloride channel proteins has been described in a variety of malignancies. However, the association between SOX2 and chloride channel proteins is not yet fully understood. The present study investigated the association between SOX2 and chloride voltage-gated channel 3 (CLC-3) in prostate cancer. Flow cytometry demonstrated that the inactivation of CLC-3 or SOX2 arrested cell cycle progression in the G0/G1 phase. Furthermore, CLC-3 was observed to bind to SOX2, and vice versa, by co-immunoprecipitation. SOX2 appears to initiate and maintain prostate cancer tumorigenesis, in part, by modulating the cell cycle. These findings indicate the potential of SOX2 and CLC-3 as targets for the development of multi-targeted therapeutics.
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Affiliation(s)
- Jiahong Chen
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Fang Wang
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Yuli Lu
- Department of Epidemiology and Health Statistics, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Shangqi Yang
- Department of Epidemiology and Health Statistics, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Xueqin Chen
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Youwei Huang
- Department of Pathology and Pathophysiology, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China
| | - Xi Lin
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, P.R. China.,Key Laboratory for Environmental Exposure and Health, Environment College, Jinan University, Guangzhou, Guangdong 510632, P.R. China
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10
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Nguyen LTS, Robinson DN. The Unusual Suspects in Cytokinesis: Fitting the Pieces Together. Front Cell Dev Biol 2020; 8:441. [PMID: 32626704 PMCID: PMC7314909 DOI: 10.3389/fcell.2020.00441] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/11/2020] [Indexed: 01/24/2023] Open
Abstract
Cytokinesis is the step of the cell cycle in which the cell must faithfully separate the chromosomes and cytoplasm, yielding two daughter cells. The assembly and contraction of the contractile network is spatially and temporally coupled with the formation of the mitotic spindle to ensure the successful completion of cytokinesis. While decades of studies have elucidated the components of this machinery, the so-called usual suspects, and their functions, many lines of evidence are pointing to other unexpected proteins and sub-cellular systems as also being involved in cytokinesis. These we term the unusual suspects. In this review, we introduce recent discoveries on some of these new unusual suspects and begin to consider how these subcellular systems snap together to help complete the puzzle of cytokinesis.
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Affiliation(s)
- Ly T. S. Nguyen
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Douglas N. Robinson
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Chemical and Biomolecular Engineering, Johns Hopkins University Whiting School of Engineering, Baltimore, MD, United States
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11
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Yokoyama R, Kojima H, Takai R, Ohta T, Maeda H, Miyashita K, Mutoh M, Terasaki M. Effects of CLIC4 on Fucoxanthinol-Induced Apoptosis in Human Colorectal Cancer Cells. Nutr Cancer 2020; 73:889-898. [PMID: 33703973 DOI: 10.1080/01635581.2020.1779760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fucoxanthin is a marine xanthophyll found in edible brown algae, and a metabolite, fucoxanthinol (FxOH), possesses a potent apoptosis inducing effect in many cancer cells. Chloride intracellular channel 4 (CLIC4) is a member of the CLIC family that plays an important role in cancer development and apoptosis. However, the role of CLIC4 in FxOH-induced apoptosis is not well understood. In this study, we investigated whether CLIC4 affects the apoptotic properties of FxOH in human colorectal cancer (CRC) cells under FxOH treatment. Treating human CRC DLD-1 cells with 5.0 μmol/L FxOH significantly induced apoptosis. FxOH downregulated CLIC4, integrin β1, NHERF2 and pSmad2 (Ser465/467) by 0.6-, 0.7-, 0.7-, and 0.5-fold, respectively, compared with control cells without alteration of Rab35 expression. No colocalizing change was observed in CLIC4-related proteins in either control or FxOH-treated cells. CLIC4 knockdown suppressed cell growth and apoptosis. Interestingly, apoptosis induction by FxOH almost disappeared with CLIC4 knockdown. Our findings suggested that CLIC4 could be involved in FxOH-induced apoptosis in human CRC.
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Affiliation(s)
- Reo Yokoyama
- School of Pharmaceutical Sciences, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Hiroyuki Kojima
- School of Pharmaceutical Sciences, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Rie Takai
- Research Institute of Health Sciences, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Tohru Ohta
- Research Institute of Health Sciences, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Hayato Maeda
- Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan
| | - Kazuo Miyashita
- Laboratory of Biofunctional Material Chemistry, Division of Marine Bioscience, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan
| | - Michihiro Mutoh
- Epidemiology and Preventions Group, Center for Public Health Sciences, National Cancer Center, Chuo-ku, Tokyo, Japan
| | - Masaru Terasaki
- School of Pharmaceutical Sciences, Health Science University of Hokkaido, Ishikari-Tobetsu, Japan.,Cancer Prevention Laboratories, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan
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12
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Wilke BU, Kummer KK, Leitner MG, Kress M. Chloride - The Underrated Ion in Nociceptors. Front Neurosci 2020; 14:287. [PMID: 32322187 PMCID: PMC7158864 DOI: 10.3389/fnins.2020.00287] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 03/12/2020] [Indexed: 01/06/2023] Open
Abstract
In contrast to pain processing neurons in the spinal cord, where the importance of chloride conductances is already well established, chloride homeostasis in primary afferent neurons has received less attention. Sensory neurons maintain high intracellular chloride concentrations through balanced activity of Na+-K+-2Cl– cotransporter 1 (NKCC1) and K+-Cl– cotransporter 2 (KCC2). Whereas in other cell types activation of chloride conductances causes hyperpolarization, activation of the same conductances in primary afferent neurons may lead to inhibitory or excitatory depolarization depending on the actual chloride reversal potential and the total amount of chloride efflux during channel or transporter activation. Dorsal root ganglion (DRG) neurons express a multitude of chloride channel types belonging to different channel families, such as ligand-gated, ionotropic γ-aminobutyric acid (GABA) or glycine receptors, Ca2+-activated chloride channels of the anoctamin/TMEM16, bestrophin or tweety-homolog family, CLC chloride channels and transporters, cystic fibrosis transmembrane conductance regulator (CFTR) as well as volume-regulated anion channels (VRACs). Specific chloride conductances are involved in signal transduction and amplification at the peripheral nerve terminal, contribute to excitability and action potential generation of sensory neurons, or crucially shape synaptic transmission in the spinal dorsal horn. In addition, chloride channels can be modified by a plethora of inflammatory mediators affecting them directly, via protein-protein interaction, or through signaling cascades. Since chloride channels as well as mediators that modulate chloride fluxes are regulated in pain disorders and contribute to nociceptor excitation and sensitization it is timely and important to emphasize their critical role in nociceptive primary afferents in this review.
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Affiliation(s)
- Bettina U Wilke
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael G Leitner
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
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13
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Argenzio E, Innocenti M. The chloride intracellular channel protein CLIC4 inhibits filopodium formation induced by constitutively active mutants of formin mDia2. FEBS Lett 2020; 594:1750-1758. [PMID: 32145706 DOI: 10.1002/1873-3468.13766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/14/2020] [Accepted: 03/02/2020] [Indexed: 11/07/2022]
Abstract
Chloride intracellular channel 4 (CLIC4) functions in diverse actin-dependent processes. Upon Rho activation, CLIC4 reversibly translocates from the cytosol to the plasma membrane to regulate cell adhesion and migration. At the plasma membrane, CLIC4 counters the formation of filopodia, which requires actin assembly by the formin mammalian Diaphanous (mDia)2. To this end, mDia2 must be activated through conversion from the closed to the open conformation. Thus, CLIC4 could harness the activation or the open conformation of mDia2 to inhibit filopodium formation. Here, we find that CLIC4 silencing enhances the filopodia induced by two constitutively active mDia2 mutants. Furthermore, we report that CLIC4 binds the actin-regulatory region of mDia2 in vitro. These results suggest that CLIC4 modulates the activity of the open conformation of mDia2, shedding new light into how cells may control filopodia.
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Affiliation(s)
- Elisabetta Argenzio
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Metello Innocenti
- Heidelberg University Biochemistry Center (BZH), Heidelberg University, Germany
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14
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Gururaja Rao S, Patel NJ, Singh H. Intracellular Chloride Channels: Novel Biomarkers in Diseases. Front Physiol 2020; 11:96. [PMID: 32116799 PMCID: PMC7034325 DOI: 10.3389/fphys.2020.00096] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/27/2020] [Indexed: 12/27/2022] Open
Abstract
Ion channels are integral membrane proteins present on the plasma membrane as well as intracellular membranes. In the human genome, there are more than 400 known genes encoding ion channel proteins. Ion channels are known to regulate several cellular, organellar, and physiological processes. Any mutation or disruption in their function can result in pathological disorders, both common or rare. Ion channels present on the plasma membrane are widely acknowledged for their role in various biological processes, but in recent years, several studies have pointed out the importance of ion channels located in intracellular organelles. However, ion channels located in intracellular organelles are not well-understood in the context of physiological conditions, such as the generation of cellular excitability and ionic homeostasis. Due to the lack of information regarding their molecular identity and technical limitations of studying them, intracellular organelle ion channels have thus far been overlooked as potential therapeutic targets. In this review, we focus on a novel class of intracellular organelle ion channels, Chloride Intracellular Ion Channels (CLICs), mainly documented for their role in cardiovascular, neurophysiology, and tumor biology. CLICs have a single transmembrane domain, and in cells, they exist in cytosolic as well as membranous forms. They are predominantly present in intracellular organelles and have recently been shown to be localized to cardiomyocyte mitochondria as well as exosomes. In fact, a member of this family, CLIC5, is the first mitochondrial chloride channel to be identified on the molecular level in the inner mitochondrial membrane, while another member, CLIC4, is located predominantly in the outer mitochondrial membrane. In this review, we discuss this unique class of intracellular chloride channels, their role in pathologies, such as cardiovascular, cancer, and neurodegenerative diseases, and the recent developments concerning their usage as theraputic targets.
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Affiliation(s)
- Shubha Gururaja Rao
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Neel J Patel
- Department of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States
| | - Harpreet Singh
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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15
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Uretmen Kagiali ZC, Saner N, Akdag M, Sanal E, Degirmenci BS, Mollaoglu G, Ozlu N. CLIC4 and CLIC1 bridge plasma membrane and cortical actin network for a successful cytokinesis. Life Sci Alliance 2019; 3:3/2/e201900558. [PMID: 31879279 PMCID: PMC6933522 DOI: 10.26508/lsa.201900558] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 11/24/2022] Open
Abstract
CLIC members are required for the progression of cytokinesis by coupling the plasma membrane and cortical actin network at the cleavage furrow and polar cortex. CLIC4 and CLIC1 are members of the well-conserved chloride intracellular channel proteins (CLICs) structurally related to glutathione-S-transferases. Here, we report new roles of CLICs in cytokinesis. At the onset of cytokinesis, CLIC4 accumulates at the cleavage furrow and later localizes to the midbody in a RhoA-dependent manner. The cell cycle–dependent localization of CLIC4 is abolished when its glutathione S-transferase activity–related residues (C35A and F37D) are mutated. Ezrin, anillin, and ALIX are identified as interaction partners of CLIC4 at the cleavage furrow and midbody. Strikingly, CLIC4 facilitates the activation of ezrin at the cleavage furrow and reciprocally inhibition of ezrin activation diminishes the translocation of CLIC4 to the cleavage furrow. Furthermore, knockouts of CLIC4and CLIC1 cause abnormal blebbing at the polar cortex and regression of the cleavage furrow at late cytokinesis leading to multinucleated cells. We conclude that CLIC4 and CLIC1 function together with ezrin where they bridge plasma membrane and actin cytoskeleton at the polar cortex and cleavage furrow to promote cortical stability and successful completion of cytokinesis in mammalian cells.
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Affiliation(s)
| | - Nazan Saner
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Mehmet Akdag
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Erdem Sanal
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | | | - Gurkan Mollaoglu
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Nurhan Ozlu
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey .,Koç University Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey
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16
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Hsu KS, Otsu W, Li Y, Wang HC, Chen S, Tsang SH, Chuang JZ, Sung CH. CLIC4 regulates late endosomal trafficking and matrix degradation activity of MMP14 at focal adhesions in RPE cells. Sci Rep 2019; 9:12247. [PMID: 31439888 PMCID: PMC6706427 DOI: 10.1038/s41598-019-48438-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 08/05/2019] [Indexed: 12/17/2022] Open
Abstract
Dysregulation in the extracellular matrix (ECM) microenvironment surrounding the retinal pigment epithelium (RPE) has been implicated in the etiology of proliferative vitreoretinopathy and age-related macular degeneration. The regulation of ECM remodeling by RPE cells is not well understood. We show that membrane-type matrix metalloproteinase 14 (MMP14) is central to ECM degradation at the focal adhesions in human ARPE19 cells. The matrix degradative activity, but not the assembly, of the focal adhesion is regulated by chloride intracellular channel 4 (CLIC4). CLIC4 is co-localized with MMP14 in the late endosome. CLIC4 regulates the proper sorting of MMP14 into the lumen of the late endosome and its proteolytic activation in lipid rafts. CLIC4 has the newly-identified “late domain” motif that binds to MMP14 and to Tsg101, a component of the endosomal sorting complex required for transport (ESCRT) complex. Unlike the late domain mutant CLIC4, wild-type CLIC4 can rescue the late endosomal sorting defect of MMP14. Finally, CLIC4 knockdown inhibits the apical secretion of MMP2 in polarized human RPE monolayers. These results, taken together, demonstrate that CLIC4 is a novel matrix microenvironment modulator and a novel regulator for late endosomal cargo sorting. Moreover, the late endosomal sorting of MMP14 actively regulates its surface activation in RPE cells.
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Affiliation(s)
- Kuo-Shun Hsu
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY, USA.,Department of Surgery, Colorectal Service and Laboratory of Signal Transduction, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Wataru Otsu
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY, USA.,Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Yao Li
- Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Heuy-Ching Wang
- Ocular Trauma Task Area, US Army Institute of Surgical Research, Joint Base San Antonio-Fort Sam Houston, TX, San Antonio, USA
| | - Shuibing Chen
- Department of Surgery and Department of Biochemistry, Weill Medical College of Cornell University, New York, NY, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.,Jonas Children's Vision Care and Bernard & Shirlee Brown Glaucoma Laboratory, Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA.,Department of Pathology & Cell Biology, and Columbia Stem Cell Initiative, Columbia University Medical Center, New York, NY, USA
| | - Jen-Zen Chuang
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY, USA
| | - Ching-Hwa Sung
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY, USA. .,Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY, USA.
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17
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Argenzio E, Klarenbeek J, Kedziora KM, Nahidiazar L, Isogai T, Perrakis A, Jalink K, Moolenaar WH, Innocenti M. Profilin binding couples chloride intracellular channel protein CLIC4 to RhoA-mDia2 signaling and filopodium formation. J Biol Chem 2018; 293:19161-19176. [PMID: 30381396 PMCID: PMC6302171 DOI: 10.1074/jbc.ra118.002779] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 10/26/2018] [Indexed: 12/31/2022] Open
Abstract
Chloride intracellular channel 4 (CLIC4) is a cytosolic protein implicated in diverse actin-based processes, including integrin trafficking, cell adhesion, and tubulogenesis. CLIC4 is rapidly recruited to the plasma membrane by RhoA-activating agonists and then partly colocalizes with β1 integrins. Agonist-induced CLIC4 translocation depends on actin polymerization and requires conserved residues that make up a putative binding groove. However, the mechanism and significance of CLIC4 trafficking have been elusive. Here, we show that RhoA activation by either lysophosphatidic acid (LPA) or epidermal growth factor is necessary and sufficient for CLIC4 translocation to the plasma membrane and involves regulation by the RhoA effector mDia2, a driver of actin polymerization and filopodium formation. We found that CLIC4 binds the G-actin–binding protein profilin-1 via the same residues that are required for CLIC4 trafficking. Consistently, shRNA-induced profilin-1 silencing impaired agonist-induced CLIC4 trafficking and the formation of mDia2-dependent filopodia. Conversely, CLIC4 knockdown increased filopodium formation in an integrin-dependent manner, a phenotype rescued by wild-type CLIC4 but not by the trafficking-incompetent mutant CLIC4(C35A). Furthermore, CLIC4 accelerated LPA-induced filopodium retraction. We conclude that through profilin-1 binding, CLIC4 functions in a RhoA–mDia2–regulated signaling network to integrate cortical actin assembly and membrane protrusion. We propose that agonist-induced CLIC4 translocation provides a feedback mechanism that counteracts formin-driven filopodium formation.
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Affiliation(s)
| | | | | | | | | | - Anastassis Perrakis
- Biochemistry, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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18
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Qi Y, Mair N, Kummer KK, Leitner MG, Camprubí-Robles M, Langeslag M, Kress M. Identification of Chloride Channels CLCN3 and CLCN5 Mediating the Excitatory Cl - Currents Activated by Sphingosine-1-Phosphate in Sensory Neurons. Front Mol Neurosci 2018; 11:33. [PMID: 29479306 PMCID: PMC5811518 DOI: 10.3389/fnmol.2018.00033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/24/2018] [Indexed: 12/27/2022] Open
Abstract
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid involved in numerous physiological and pathophysiological processes. We have previously reported a S1P-induced nocifensive response in mice by excitation of sensory neurons via activation of an excitatory chloride current. The underlying molecular mechanism for the S1P-induced chloride conductance remains elusive. In the present study, we identified two CLCN voltage-gated chloride channels, CLCN3 and CLCN5, which mediated a S1P-induced excitatory Cl- current in sensory neurons by combining RNA-seq, adenovirus-based gene silencing and whole-cell electrophysiological voltage-clamp recordings. Downregulation of CLCN3 and CLCN5 channels by adenovirus-mediated delivery of shRNA dramatically reduced S1P-induced Cl- current and membrane depolarization in sensory neurons. The mechanism of S1P-induced activation of the chloride current involved Rho GTPase but not Rho-associated protein kinase. Although S1P-induced potentiation of TRPV1-mediated ionic currents also involved Rho-dependent process, the lack of correlation of the S1P-activated Cl- current and the potentiation of TRPV1 by S1P suggests that CLCN3 and CLCN5 are necessary components for S1P-induced excitatory Cl- currents but not for the amplification of TRPV1-mediated currents in sensory neurons. This study provides a novel mechanistic insight into the importance of bioactive sphingolipids in nociception.
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Affiliation(s)
- Yanmei Qi
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Norbert Mair
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael G Leitner
- Department of Neurophysiology, Philipps University of Marburg, Marburg, Germany
| | - María Camprubí-Robles
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michiel Langeslag
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
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19
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Argenzio E, Moolenaar WH. Emerging biological roles of Cl- intracellular channel proteins. J Cell Sci 2017; 129:4165-4174. [PMID: 27852828 DOI: 10.1242/jcs.189795] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cl- intracellular channels (CLICs) are a family of six evolutionary conserved cytosolic proteins that exist in both soluble and membrane-associated forms; however, their functions have long been elusive. Soluble CLICs adopt a glutathione S-transferase (GST)-fold, can induce ion currents in artificial membranes and show oxidoreductase activity in vitro, but there is no convincing evidence of CLICs having such activities in vivo. Recent studies have revealed a role for CLIC proteins in Rho-regulated cortical actin dynamics as well as vesicular trafficking and integrin recycling, the latter of which are under the control of Rab GTPases. In this Commentary, we discuss the emerging roles of CLIC proteins in these processes and the lessons learned from gene-targeting studies. We also highlight outstanding questions regarding the molecular function(s) of these important but still poorly understood proteins.
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Affiliation(s)
- Elisabetta Argenzio
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Wouter H Moolenaar
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
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20
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Brum AM, van der Leije CS, Schreuders-Koedam M, Verhoeven J, Janssen M, Dekkers DH, Demmers JA, Eijken M, van de Peppel J, van Leeuwen JP, van der Eerden BC. Identification of Chloride Intracellular Channel Protein 3 as a Novel Gene Affecting Human Bone Formation. JBMR Plus 2017; 1:16-26. [PMID: 30283877 PMCID: PMC6124162 DOI: 10.1002/jbm4.10003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 03/09/2017] [Indexed: 12/14/2022] Open
Abstract
Osteoporosis is a common skeletal disorder characterized by low bone mass leading to increased bone fragility and fracture susceptibility. The bone building cells, osteoblasts, are derived from mesenchymal stromal cells (MSCs); however, with increasing age osteogenic differentiation is diminished and more adipocytes are seen in the bone marrow, suggesting a shift in MSC lineage commitment. Identification of specific factors that stimulate osteoblast differentiation from human MSCs may deliver therapeutic targets to treat osteoporosis. The aim of this study was to identify novel genes involved in osteoblast differentiation of human bone marrow–derived MSCs (hMSCs). We identified the gene chloride intracellular channel protein 3 (CLIC3) to be strongly upregulated during MSC‐derived osteoblast differentiation. Lentiviral overexpression of CLIC3 in hMSCs caused a 60% increase of matrix mineralization. Conversely, knockdown of CLIC3 in hMSCs using two short‐hairpin RNAs (shRNAs) against CLIC3 resulted in a 69% to 76% reduction in CLIC3 mRNA expression, 53% to 37% less alkaline phosphatase (ALP) activity, and 78% to 88% less matrix mineralization compared to scrambled control. Next, we used an in vivo human bone formation model in which hMSCs lentivirally transduced with the CLIC3 overexpression construct were loaded onto a scaffold (hydroxyapatite‐tricalcium‐phosphate), implanted under the skin of NOD‐SCID mice, and analyzed for bone formation 8 weeks later. CLIC3 overexpression led to a 15‐fold increase in bone formation (0.33% versus 5.05% bone area relative to scaffold). Using a Clic3‐His‐tagged pull‐down assay and liquid chromatography–mass spectrometry (LS/MS)‐based proteomics analysis in lysates of osteogenically differentiated hMSCs, we showed that CLIC3 interacts with NIMA‐related kinase 9 (NEK9) and phosphatidylserine synthase 1 (PTDSS1) in vitro, and this finding was supported by immunofluorescent analysis. In addition, inhibition of NEK9 or PTDSS1 gene expression by shRNAs inhibited osteoblast differentiation and mineralization. In conclusion, we successfully identified CLIC3 to be a lineage‐specific gene regulating osteoblast differentiation and bone formation through its interaction with NEK9 and PTDSS1. © The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
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Affiliation(s)
- Andrea M Brum
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | - Cindy S van der Leije
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | - Marijke Schreuders-Koedam
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | - Jeroen Verhoeven
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | | | - Dick Hw Dekkers
- Proteomics Center Erasmus University Medical Center Rotterdam The Netherlands
| | - Jeroen Aa Demmers
- Proteomics Center Erasmus University Medical Center Rotterdam The Netherlands
| | | | - Jeroen van de Peppel
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | - Johannes Ptm van Leeuwen
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
| | - Bram Cj van der Eerden
- Department of Internal Medicine School of Molecular Medicine Erasmus University Medical Center Rotterdam the Netherlands
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21
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Tavasoli M, Al-Momany A, Wang X, Li L, Edwards JC, Ballermann BJ. Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium. Am J Physiol Renal Physiol 2016; 311:F945-F957. [PMID: 27582103 DOI: 10.1152/ajprenal.00353.2016] [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: 06/13/2016] [Accepted: 08/25/2016] [Indexed: 01/17/2023] Open
Abstract
The chloride intracellular channel (CLIC) 5A is expressed at very high levels in renal glomeruli, in both endothelial cells (EC) and podocytes. CLIC5A stimulates Rac1- and phosphatidylinositol (4,5)-bisphosphate-dependent ERM (ezrin, radixin, moesin) activation. ERM proteins, in turn, function in lumen formation and in the development of actin-based cellular projections. In mice lacking CLIC5A, ERM phosphorylation is profoundly reduced in podocytes, but preserved in glomerular EC. Since glomerular EC also express CLIC4, we reasoned that, if CLIC4 activates ERM proteins like CLIC5A, then CLIC4 could compensate for the CLIC5A loss in glomerular EC. In glomeruli of CLIC5-deficient mice, CLIC4 expression was upregulated and colocalized with moesin and ezrin in glomerular EC, but not in podocytes. In cultured glomerular EC, CLIC4 silencing reduced ERM phosphorylation and cytoskeletal association, and expression of exogenous CLIC4 or CLIC5A rescued ERM de-phosphorylation due to CLIC4 silencing. In mice lacking either CLIC4 or CLIC5, ERM phosphorylation was retained in glomerular EC, but, in mice lacking both CLIC4 and CLIC5, glomerular EC ERM phosphorylation was profoundly reduced. Although glomerular EC fenestrae developed normally in dual CLIC4/CLIC5-deficient mice, the density of fenestrae declined substantially by 8 mo of age, along with the deposition of subendothelial electron-lucent material. The dual CLIC4/CLIC5-deficient mice developed spontaneous proteinuria, glomerular cell proliferation, and matrix deposition. Thus CLIC4 stimulates ERM activation and can compensate for CLIC5A in glomerular EC. The findings indicate that CLIC4/CLIC5A-mediated ERM activation is required for maintenance of the glomerular capillary architecture.
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Affiliation(s)
- Mahtab Tavasoli
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Abass Al-Momany
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
| | - Xin Wang
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Laiji Li
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - John C Edwards
- Department of Internal Medicine, St. Louis University, St. Louis, Missouri
| | - Barbara J Ballermann
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; .,Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
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CLIC4 regulates apical exocytosis and renal tube luminogenesis through retromer- and actin-mediated endocytic trafficking. Nat Commun 2016; 7:10412. [PMID: 26786190 PMCID: PMC4736046 DOI: 10.1038/ncomms10412] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 12/04/2015] [Indexed: 02/07/2023] Open
Abstract
Chloride intracellular channel 4 (CLIC4) is a mammalian homologue of EXC-4 whose mutation is associated with cystic excretory canals in nematodes. Here we show that CLIC4-null mouse embryos exhibit impaired renal tubulogenesis. In both developing and developed kidneys, CLIC4 is specifically enriched in the proximal tubule epithelial cells, in which CLIC4 is important for luminal delivery, microvillus morphogenesis, and endolysosomal biogenesis. Adult CLIC4-null proximal tubules display aberrant dilation. In MDCK 3D cultures, CLIC4 is expressed on early endosome, recycling endosome and apical transport carriers before reaching its steady-state apical membrane localization in mature lumen. CLIC4 suppression causes impaired apical vesicle coalescence and central lumen formation, a phenotype that can be rescued by Rab8 and Cdc42. Furthermore, we show that retromer- and branched actin-mediated trafficking on early endosome regulates apical delivery during early luminogenesis. CLIC4 selectively modulates retromer-mediated apical transport by negatively regulating the formation of branched actin on early endosomes. Chloride intracellular channel (CLIC) 4 is an ion channel, localized in the cytoplasm, and first identified as an actin binding protein. Here, Chou et al. knockout CLIC4 in mice and observe tubulogenesis and renal proximal tubule dilation defects, which is caused by irregular actin and endosomal trafficking.
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23
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Transcriptional over-expression of chloride intracellular channels 3 and 4 in malignant pleural mesothelioma. Comput Biol Chem 2015; 59 Pt A:111-6. [DOI: 10.1016/j.compbiolchem.2015.09.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 08/19/2015] [Accepted: 09/24/2015] [Indexed: 01/09/2023]
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Lucitti JL, Tarte NJ, Faber JE. Chloride intracellular channel 4 is required for maturation of the cerebral collateral circulation. Am J Physiol Heart Circ Physiol 2015; 309:H1141-50. [PMID: 26276819 DOI: 10.1152/ajpheart.00451.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/13/2015] [Indexed: 12/20/2022]
Abstract
The number and diameter of native collaterals in tissues of healthy mice vary widely, resulting in large differences in tissue injury in occlusive diseases. Recent studies suggest similar variation may exist in humans. Collateral variation in mice is determined by genetic background-dependent differences in embryonic collateral formation, by variation in maturation of the nascent collaterals, and by environmental factors such as aging that cause collateral rarefaction in the adult. Recently, formation of the collateral circulation in the brain was found to involve a unique VEGF-A-dependent "arteriolar" angiogenic sprouting-like mechanism. Elsewhere, chloride intracellular protein 4 (CLIC4) was implicated but not investigated directly, prompting the present study. Deletion of Clic4 had no effect on embryonic collaterogenesis. However, during collateral maturation from embryonic day 18.5 to postnatal day 7, reduced mural cell investment was observed and excessive pruning of collaterals occurred. Growth in collateral diameter was reduced. This resulted in 50% fewer collaterals of smaller diameter in the adult and thus larger infarct volume after middle cerebral artery occlusion. During collateral maturation, CLIC4 deficiency resulted in reduced expression of Vegfr2, Vegfr1, Vegfc, and mural cell markers, but not notch-pathway genes. Overexpression of VEGF-A in Clic4(-/-) mice had no effect on collaterogenesis, but rescued the above defects in collateral maturation by preventing mural cell loss and collateral pruning, thus restoring collateral number and diameter and reducing stroke severity in the adult. CLIC4 is not required for collaterogenesis but is essential for perinatal maturation of nascent collaterals through a mechanism that supports VEGF signaling.
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Affiliation(s)
- Jennifer L Lucitti
- Department of Cell Biology and Physiology and the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Natalie J Tarte
- Department of Cell Biology and Physiology and the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - James E Faber
- Department of Cell Biology and Physiology and the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Lecat S, Matthes HWD, Pepperkok R, Simpson JC, Galzi JL. A Fluorescent Live Imaging Screening Assay Based on Translocation Criteria Identifies Novel Cytoplasmic Proteins Implicated in G Protein-coupled Receptor Signaling Pathways. Mol Cell Proteomics 2015; 14:1385-99. [PMID: 25759509 PMCID: PMC4424407 DOI: 10.1074/mcp.m114.046698] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/20/2015] [Indexed: 12/13/2022] Open
Abstract
Several cytoplasmic proteins that are involved in G protein-coupled receptor signaling cascades are known to translocate to the plasma membrane upon receptor activation, such as beta-arrestin2. Based on this example and in order to identify new cytoplasmic proteins implicated in the ON-and-OFF cycle of G protein-coupled receptor, a live-imaging screen of fluorescently labeled cytoplasmic proteins was performed using translocation criteria. The screening of 193 fluorescently tagged human proteins identified eight proteins that responded to activation of the tachykinin NK2 receptor by a change in their intracellular localization. Previously we have presented the functional characterization of one of these proteins, REDD1, that translocates to the plasma membrane. Here we report the results of the entire screening. The process of cell activation was recorded on videos at different time points and all the videos can be visualized on a dedicated website. The proteins BAIAP3 and BIN1, partially translocated to the plasma membrane upon activation of NK2 receptors. Proteins ARHGAP12 and PKM2 translocated toward membrane blebs. Three proteins that associate with the cytoskeleton were of particular interest : PLEKHH2 rearranged from individual dots located near the cell-substrate adhesion surface into lines of dots. The speriolin-like protein, SPATC1L, redistributed to cell-cell junctions. The Chloride intracellular Channel protein, CLIC2, translocated from actin-enriched plasma membrane bundles to cell-cell junctions upon activation of NK2 receptors. CLIC2, and one of its close paralogs, CLIC4, were further shown to respond with the same translocation pattern to muscarinic M3 and lysophosphatidic LPA receptors. This screen allowed us to identify potential actors in signaling pathways downstream of G protein-coupled receptors and could be scaled-up for high-content screening.
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Affiliation(s)
- Sandra Lecat
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France;
| | - Hans W D Matthes
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
| | - Rainer Pepperkok
- §European Molecular Biology Laboratory, Advanced Light Microscopy Facility, Meyerhofstr 1, 69117 Heidelberg, Germany
| | - Jeremy C Simpson
- ¶¶School of Biology and Environmental Science and UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jean-Luc Galzi
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
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26
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Özlü N, Qureshi MH, Toyoda Y, Renard BY, Mollaoglu G, Özkan NE, Bulbul S, Poser I, Timm W, Hyman AA, Mitchison TJ, Steen JA. Quantitative comparison of a human cancer cell surface proteome between interphase and mitosis. EMBO J 2014; 34:251-65. [PMID: 25476450 DOI: 10.15252/embj.201385162] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The cell surface is the cellular compartment responsible for communication with the environment. The interior of mammalian cells undergoes dramatic reorganization when cells enter mitosis. These changes are triggered by activation of the CDK1 kinase and have been studied extensively. In contrast, very little is known of the cell surface changes during cell division. We undertook a quantitative proteomic comparison of cell surface-exposed proteins in human cancer cells that were tightly synchronized in mitosis or interphase. Six hundred and twenty-eight surface and surface-associated proteins in HeLa cells were identified; of these, 27 were significantly enriched at the cell surface in mitosis and 37 in interphase. Using imaging techniques, we confirmed the mitosis-selective cell surface localization of protocadherin PCDH7, a member of a family with anti-adhesive roles in embryos. We show that PCDH7 is required for development of full mitotic rounding pressure at the onset of mitosis. Our analysis provided basic information on how cell cycle progression affects the cell surface. It also provides potential pharmacodynamic biomarkers for anti-mitotic cancer chemotherapy.
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Affiliation(s)
- Nurhan Özlü
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey Proteomics Center at Children's Hospital Boston, Boston, MA, USA Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Mohammad H Qureshi
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Yusuke Toyoda
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Bernhard Y Renard
- Research Group Bioinformatics (NG 4), Robert Koch-Institute, Berlin, Germany
| | - Gürkan Mollaoglu
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Nazlı E Özkan
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Selda Bulbul
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Ina Poser
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Wiebke Timm
- Proteomics Center at Children's Hospital Boston, Boston, MA, USA
| | - Anthony A Hyman
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Judith A Steen
- Proteomics Center at Children's Hospital Boston, Boston, MA, USA Department of Neurobiology, Harvard Medical School and Children's Hospital Boston, Boston, MA, USA
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Argenzio E, Margadant C, Leyton-Puig D, Janssen H, Jalink K, Sonnenberg A, Moolenaar WH. CLIC4 regulates cell adhesion and β1 integrin trafficking. J Cell Sci 2014; 127:5189-203. [DOI: 10.1242/jcs.150623] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Chloride intracellular channel (CLIC) protein CLIC4 exists in both soluble and membrane-associated forms, and is implicated in diverse cellular processes, ranging from ion channel formation to intracellular membrane remodeling. CLIC4 is rapidly recruited to the plasma membrane by lysophosphatidic acid (LPA) and serum, suggesting a possible role for CLIC4 in exocytic-endocytic trafficking. However, the function and subcellular target(s) of CLIC4 remain elusive. Here we show that in HeLa and MDA-MB-231 cells, CLIC4 knockdown decreases cell-matrix adhesion, cell spreading and integrin signalling, while increasing cell motility. LPA stimulates the recruitment of CLIC4 to β1 integrins at the plasma membrane and in Rab35-positive endosomes. CLIC4 is required for both the internalization and the serum/LPA-induced recycling of β1 integrins, but not for EGF receptor trafficking. Furthermore, we show that CLIC4 suppresses Rab35 activity and antagonizes Rab35-dependent regulation of β1-integrin trafficking. Our results define CLIC4 as a regulator of Rab35 activity and serum/LPA-dependent integrin trafficking.
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28
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Tung JJ, Tattersall IW, Kitajewski J. Tips, stalks, tubes: notch-mediated cell fate determination and mechanisms of tubulogenesis during angiogenesis. Cold Spring Harb Perspect Med 2013; 2:a006601. [PMID: 22355796 DOI: 10.1101/cshperspect.a006601] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Angiogenesis is the process of developing vascular sprouts from existing blood vessels. Luminal endothelial cells convert into "tip" cells that contribute to the development of a multicellular stalk, which then undergoes lumen formation. In this review, we consider a variety of cellular and molecular pathways that mediate these transitions. We focus first on Notch signaling in cell fate determination as a mechanism to define tip and stalk cells. We next discuss the current models of lumen formation and describe new players in this process, such as chloride intracellular channel proteins. Finally, we consider the possible medical therapeutic benefits of understanding these processes and acknowledge potential obstacles in drug development.
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Affiliation(s)
- Jennifer J Tung
- Department of Obstetrics/Gynecology and Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York 10032, USA
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29
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Jiang L, Phang JM, Yu J, Harrop SJ, Sokolova AV, Duff AP, Wilk KE, Alkhamici H, Breit SN, Valenzuela SM, Brown LJ, Curmi PMG. CLIC proteins, ezrin, radixin, moesin and the coupling of membranes to the actin cytoskeleton: a smoking gun? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:643-57. [PMID: 23732235 DOI: 10.1016/j.bbamem.2013.05.025] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 12/20/2022]
Abstract
The CLIC proteins are a highly conserved family of metazoan proteins with the unusual ability to adopt both soluble and integral membrane forms. The physiological functions of CLIC proteins may include enzymatic activity in the soluble form and anion channel activity in the integral membrane form. CLIC proteins are associated with the ERM proteins: ezrin, radixin and moesin. ERM proteins act as cross-linkers between membranes and the cortical actin cytoskeleton. Both CLIC and ERM proteins are controlled by Rho family small GTPases. CLIC proteins, ERM and Rho GTPases act in a concerted manner to control active membrane processes including the maintenance of microvillar structures, phagocytosis and vesicle trafficking. All of these processes involve the interaction of membranes with the underlying cortical actin cytoskeleton. The relationships between Rho GTPases, CLIC proteins, ERM proteins and the membrane:actin cytoskeleton interface are reviewed. Speculative models are proposed involving the formation of localised multi-protein complexes on the membrane surface that assemble via multiple weak interactions. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Lele Jiang
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia
| | - Juanita M Phang
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Jiang Yu
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Stephen J Harrop
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Anna V Sokolova
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Anthony P Duff
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Krystyna E Wilk
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Heba Alkhamici
- School of Medical and Molecular Biosciences, The University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Samuel N Breit
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia
| | - Stella M Valenzuela
- School of Medical and Molecular Biosciences, The University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Louise J Brown
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Paul M G Curmi
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia; School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia.
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30
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Sphingosine-1-phosphate-induced nociceptor excitation and ongoing pain behavior in mice and humans is largely mediated by S1P3 receptor. J Neurosci 2013; 33:2582-92. [PMID: 23392686 DOI: 10.1523/jneurosci.4479-12.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The biolipid sphingosine-1-phosphate (S1P) is an essential modulator of innate immunity, cell migration, and wound healing. It is released locally upon acute tissue injury from endothelial cells and activated thrombocytes and, therefore, may give rise to acute post-traumatic pain sensation via a yet elusive molecular mechanism. We have used an interdisciplinary approach to address this question, and we find that intradermal injection of S1P induced significant licking and flinching behavior in wild-type mice and a dose-dependent flare reaction in human skin as a sign of acute activation of nociceptive nerve terminals. Notably, S1P evoked a small excitatory ionic current that resulted in nociceptor depolarization and action potential firing. This ionic current was preserved in "cation-free" solution and blocked by the nonspecific Cl(-) channel inhibitor niflumic acid and by preincubation with the G-protein inhibitor GDP-β-S. Notably, S1P(3) receptor was detected in virtually all neurons in human and mouse DRG. In line with this finding, S1P-induced neuronal responses and spontaneous pain behavior in vivo were substantially reduced in S1P(3)(-/-) mice, whereas in control S1P(1) floxed (S1P(1)(fl/fl)) mice and mice with a nociceptor-specific deletion of S1P(1)(-/-) receptor (SNS-S1P(1)(-/-)), neither the S1P-induced responses in vitro nor the S1P-evoked pain-like behavior was altered. Therefore, these findings indicate that S1P evokes significant nociception via G-protein-dependent activation of an excitatory Cl(-) conductance that is largely mediated by S1P(3) receptors present in nociceptors, and point to these receptors as valuable therapeutic targets for post-traumatic pain.
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31
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Shin JB, Krey JF, Hassan A, Metlagel Z, Tauscher AN, Pagana JM, Sherman NE, Jeffery ED, Spinelli KJ, Zhao H, Wilmarth PA, Choi D, David LL, Auer M, Barr-Gillespie PG. Molecular architecture of the chick vestibular hair bundle. Nat Neurosci 2013; 16:365-74. [PMID: 23334578 PMCID: PMC3581746 DOI: 10.1038/nn.3312] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 12/17/2012] [Indexed: 12/31/2022]
Abstract
Hair bundles of the inner ear have a specialized structure and protein composition that underlies their sensitivity to mechanical stimulation. Using mass spectrometry, we identified and quantified >1,100 proteins, present from a few to 400,000 copies per stereocilium, from purified chick bundles; 336 of these were significantly enriched in bundles. Bundle proteins that we detected have been shown to regulate cytoskeleton structure and dynamics, energy metabolism, phospholipid synthesis and cell signaling. Three-dimensional imaging using electron tomography allowed us to count the number of actin-actin cross-linkers and actin-membrane connectors; these values compared well to those obtained from mass spectrometry. Network analysis revealed several hub proteins, including RDX (radixin) and SLC9A3R2 (NHERF2), which interact with many bundle proteins and may perform functions essential for bundle structure and function. The quantitative mass spectrometry of bundle proteins reported here establishes a framework for future characterization of dynamic processes that shape bundle structure and function.
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Affiliation(s)
- Jung-Bum Shin
- Department of Neuroscience, University of Virginia, Charlottesville, Virginia, USA
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32
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Zhong J, Kong X, Zhang H, Yu C, Xu Y, Kang J, Yu H, Yi H, Yang X, Sun L. Inhibition of CLIC4 enhances autophagy and triggers mitochondrial and ER stress-induced apoptosis in human glioma U251 cells under starvation. PLoS One 2012; 7:e39378. [PMID: 22761775 PMCID: PMC3382619 DOI: 10.1371/journal.pone.0039378] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/21/2012] [Indexed: 12/19/2022] Open
Abstract
CLIC4/mtCLIC, a chloride intracellular channel protein, localizes to mitochondria, endoplasmic reticulum (ER), nucleus and cytoplasm, and participates in the apoptotic response to stress. Apoptosis and autophagy, the main types of the programmed cell death, seem interconnected under certain stress conditions. However, the role of CLIC4 in autophagy regulation has yet to be determined. In this study, we demonstrate upregulation and nuclear translocation of the CLIC4 protein following starvation in U251 cells. CLIC4 siRNA transfection enhanced autophagy with increased LC3-II protein and puncta accumulation in U251 cells under starvation conditions. In that condition, the interaction of the 14-3-3 epsilon isoform with CLIC4 was abolished and resulted in Beclin 1 overactivation, which further activated autophagy. Moreover, inhibiting the expression of CLIC4 triggered both mitochondrial apoptosis involved in Bax/Bcl-2 and cytochrome c release under starvation and endoplasmic reticulum stress-induced apoptosis with CHOP and caspase-4 upregulation. These results demonstrate that CLIC4 nuclear translocation is an integral part of the cellular response to starvation. Inhibiting the expression of CLIC4 enhances autophagy and contributes to mitochondrial and ER stress-induced apoptosis under starvation.
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Affiliation(s)
- Jiateng Zhong
- Department of Pathophysiology, Norman Bethune College of Medicine, Jilin University, Changchun, Jilin, China
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33
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Suh KS, Malik M, Shukla A, Ryscavage A, Wright L, Jividen K, Crutchley JM, Dumont RA, Fernandez-Salas E, Webster JD, Simpson RM, Yuspa SH. CLIC4 is a tumor suppressor for cutaneous squamous cell cancer. Carcinogenesis 2012; 33:986-95. [PMID: 22387366 DOI: 10.1093/carcin/bgs115] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Chloride intracellular channel (CLIC) 4 is a member of a redox-regulated, metamorphic multifunctional protein family, first characterized as intracellular chloride channels. Current knowledge indicates that CLICs participate in signaling, cytoskeleton integrity and differentiation functions of multiple tissues. In metabolically stressed skin keratinocytes, cytoplasmic CLIC4 is S-nitrosylated and translocates to the nucleus where it enhances transforming growth factor-β (TGF-β) signaling by protecting phospho-Smad 2 and 3 from dephosphorylation. CLIC4 expression is diminished in multiple human epithelial cancers, and the protein is excluded from the nucleus. We now show that CLIC4 expression is reduced in chemically induced mouse skin papillomas, mouse and human squamous carcinomas and squamous cancer cell lines, and the protein is excluded from the nucleus. The extent of reduction in CLIC4 coincides with progression of squamous tumors from benign to malignant. Inhibiting antioxidant defense in tumor cells increases S-nitrosylation and nuclear translocation of CLIC4. Adenoviral-mediated reconstitution of nuclear CLIC4 in squamous cancer cells enhances TGF-β-dependent transcriptional activity and inhibits growth. Adenoviral targeting of CLIC4 to the nucleus of tumor cells in orthografts inhibits tumor growth, whereas elevation of CLIC4 in transgenic epidermis reduces de novo chemically induced skin tumor formation. In parallel, overexpression of exogenous CLIC4 in squamous tumor orthografts suppresses tumor growth and enhances TGF-β signaling. These results indicate that CLIC4 suppresses the growth of squamous cancers, that reduced CLIC4 expression and nuclear residence detected in cancer cells is associated with the altered redox state of tumor cells and the absence of detectable nuclear CLIC4 in cancers contributes to TGF-β resistance and enhances tumor development.
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Affiliation(s)
- K Stephen Suh
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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Palmfeldt J, Vang S, Stenbroen V, Pavlou E, Baycheva M, Buchal G, Monavari AA, Augoustides-Savvopoulou P, Mandel H, Gregersen N. Proteomics reveals that redox regulation is disrupted in patients with ethylmalonic encephalopathy. J Proteome Res 2011; 10:2389-96. [PMID: 21410200 DOI: 10.1021/pr101218d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Deficiency of the sulfide metabolizing protein ETHE1 is the cause of ethylmalonic encephalopathy (EE), an inherited and severe metabolic disorder. To study the molecular effects of EE, we performed a proteomics study on mitochondria from cultured patient fibroblast cells. Samples from six patients were analyzed and revealed seven differentially regulated proteins compared with healthy controls. Two proteins involved in pathways of detoxification and oxidative/reductive stress were underrepresented in EE patient samples: mitochondrial superoxide dismutase (SOD2) and aldehyde dehydrogenase X (ALDH1B). Sulfide:quinone oxidoreductase (SQRDL), which takes part in the same sulfide pathway as ETHE1, was also underrepresented in EE patients. The other differentially regulated proteins were apoptosis inducing factor (AIFM1), lactate dehydrogenase (LDHB), chloride intracellular channel (CLIC4) and dimethylarginine dimethylaminohydrolase 1 (DDAH1). These proteins have been reported to be involved in encephalopathy, energy metabolism, ion transport, and nitric oxide regulation, respectively. Interestingly, oxidoreductase activity was overrepresented among the regulated proteins indicating that redox perturbation plays an important role in the molecular mechanism of EE. This observation may explain the wide range of symptoms associated with the disease, and highlights the potency of the novel gaseous mediator sulfide.
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Affiliation(s)
- Johan Palmfeldt
- Research Unit for Molecular Medicine, Aarhus University Hospital, Skejby, Denmark.
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35
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Abdul-Salam VB, Wharton J, Cupitt J, Berryman M, Edwards RJ, Wilkins MR. Proteomic analysis of lung tissues from patients with pulmonary arterial hypertension. Circulation 2010; 122:2058-67. [PMID: 21041689 DOI: 10.1161/circulationaha.110.972745] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pulmonary arterial hypertension is a disorder of vascular remodeling causing increased resistance to pulmonary blood flow. The expression of proteins in lungs from pulmonary arterial hypertension patients was investigated in an unbiased approach to further understand the pathobiology of this disease. METHODS AND RESULTS Label-free liquid chromatography tandem mass spectrometry was used to compare protein profiles in surgical samples of lungs from 8 patients with pulmonary arterial hypertension and 8 control subjects. More than 300 proteins were detected. On the basis of robust criteria, the levels of 25 proteins varied between the 2 groups. The majority of upregulated proteins were associated with cell growth, proliferation, and cell metabolism. Novel findings included an increased expression of chloride intracellular channel 4, receptor for advanced glycation end products, and periostin. Increased expression of chloride intracellular channel 4, a multifunctional protein involved in angiogenesis, and several signaling pathways implicated in pulmonary arterial hypertension--transforming growth factor-β, vascular endothelial growth factor, and bone morphogenetic protein--was confirmed by Western blotting and localized predominantly to endothelial cells in occlusive and plexiform vascular lesions. CONCLUSIONS Label-free proteomics identified differences in the expression of several proteins in the pulmonary arterial hypertension lung, many of which are relevant to the disease process. Increased expression of chloride intracellular channel 4 may be pertinent to the disorganized angiogenesis of plexiform lesions.
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Affiliation(s)
- Vahitha B Abdul-Salam
- Centre for Pharmacology and Therapeutics, Department of Medicine, Imperial College London, London, UK
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36
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Goodchild SC, Howell MW, Littler DR, Mandyam RA, Sale KL, Mazzanti M, Breit SN, Curmi PMG, Brown LJ. Metamorphic response of the CLIC1 chloride intracellular ion channel protein upon membrane interaction. Biochemistry 2010; 49:5278-89. [PMID: 20507120 DOI: 10.1021/bi100111c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A striking feature of the CLIC (chloride intracellular channel) protein family is the ability of its members to convert between a soluble state and an integral membrane channel form. Direct evidence of the structural transition required for the CLIC protein to autonomously insert into the membrane is lacking, largely because of the challenge of probing the conformation of the membrane-bound protein. However, insights into the CLIC transmembrane form can be gained by biophysical methods such as fluorescence resonance energy transfer (FRET) spectroscopy. This approach was used to measure distances from tryptophan 35, located within the CLIC1 putative N-domain transmembrane region, to three native cysteine residues within the C-terminal domain. These distances were computed both in aqueous solution and upon the addition of membrane vesicles. The FRET distances were used as constraints for modeling of a structure for the CLIC1 integral membrane form. The data are suggestive of a large conformational unfolding occurring between the N- and C-domains of CLIC1 upon interaction with the membrane. Consistent with previous findings, the N-terminal domain of CLIC1 is likely to insert into the lipid bilayer, while the C-domain remains in solution on the extravesicular side of the membrane.
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Affiliation(s)
- Sophia C Goodchild
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Littler DR, Brown LJ, Breit SN, Perrakis A, Curmi PMG. Structure of human CLIC3 at 2 A resolution. Proteins 2010; 78:1594-600. [PMID: 20146363 DOI: 10.1002/prot.22675] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- D R Littler
- Department of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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38
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Wegner B, Al-Momany A, Kulak SC, Kozlowski K, Obeidat M, Jahroudi N, Paes J, Berryman M, Ballermann BJ. CLIC5A, a component of the ezrin-podocalyxin complex in glomeruli, is a determinant of podocyte integrity. Am J Physiol Renal Physiol 2010; 298:F1492-503. [PMID: 20335315 DOI: 10.1152/ajprenal.00030.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The chloride intracellular channel 5A (CLIC5A) protein, one of two isoforms produced by the CLIC5 gene, was isolated originally as part of a cytoskeletal protein complex containing ezrin from placental microvilli. Whether CLIC5A functions as a bona fide ion channel is controversial. We reported previously that a CLIC5 transcript is enriched approximately 800-fold in human renal glomeruli relative to most other tissues. Therefore, this study sought to explore CLIC5 expression and function in glomeruli. RT-PCR and Western blots show that CLIC5A is the predominant CLIC5 isoform expressed in glomeruli. Confocal immunofluorescence and immunogold electron microscopy reveal high levels of CLIC5A protein in glomerular endothelial cells and podocytes. In podocytes, CLIC5A localizes to the apical plasma membrane of foot processes, similar to the known distribution of podocalyxin and ezrin. Ezrin and podocalyxin colocalize with CLIC5A in glomeruli, and podocalyxin coimmunoprecipitates with CLIC5A from glomerular lysates. In glomeruli of jitterbug (jbg/jbg) mice, which lack the CLIC5A protein, ezrin and phospho-ERM levels in podocytes are markedly lower than in wild-type mice. Transmission electron microscopy reveals patchy broadening and effacement of podocyte foot processes as well as vacuolization of glomerular endothelial cells. These ultrastructural changes are associated with microalbuminuria at baseline and increased susceptibility to adriamycin-induced glomerular injury compared with wild-type mice. Together, the data suggest that CLIC5A is required for the development and/or maintenance of the proper glomerular endothelial cell and podocyte architecture. We postulate that the interaction between podocalyxin and subjacent filamentous actin, which requires ezrin, is compromised in podocytes of CLIC5A-deficient mice, leading to dysfunction under unfavorable genetic or environmental conditions.
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Affiliation(s)
- Binytha Wegner
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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39
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Two decades with dimorphic Chloride Intracellular Channels (CLICs). FEBS Lett 2010; 584:2112-21. [DOI: 10.1016/j.febslet.2010.03.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 01/11/2023]
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40
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Chloride channels of intracellular membranes. FEBS Lett 2010; 584:2102-11. [PMID: 20100480 DOI: 10.1016/j.febslet.2010.01.037] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 01/13/2010] [Accepted: 01/19/2010] [Indexed: 11/20/2022]
Abstract
Proteins implicated as intracellular chloride channels include the intracellular ClC proteins, the bestrophins, the cystic fibrosis transmembrane conductance regulator, the CLICs, and the recently described Golgi pH regulator. This paper examines current hypotheses regarding roles of intracellular chloride channels and reviews the evidence supporting a role in intracellular chloride transport for each of these proteins.
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41
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Littler DR, Harrop SJ, Goodchild SC, Phang JM, Mynott AV, Jiang L, Valenzuela SM, Mazzanti M, Brown LJ, Breit SN, Curmi PMG. The enigma of the CLIC proteins: Ion channels, redox proteins, enzymes, scaffolding proteins? FEBS Lett 2010; 584:2093-101. [PMID: 20085760 DOI: 10.1016/j.febslet.2010.01.027] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 12/13/2022]
Abstract
Chloride intracellular channel proteins (CLICs) are distinct from most ion channels in that they have both soluble and integral membrane forms. CLICs are highly conserved in chordates, with six vertebrate paralogues. CLIC-like proteins are found in other metazoans. CLICs form channels in artificial bilayers in a process favoured by oxidising conditions and low pH. They are structurally plastic, with CLIC1 adopting two distinct soluble conformations. Phylogenetic and structural data indicate that CLICs are likely to have enzymatic function. The physiological role of CLICs appears to be maintenance of intracellular membranes, which is associated with tubulogenesis but may involve other substructures.
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Affiliation(s)
- Dene R Littler
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
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