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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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Bezbradica JS, Bryant CE. Inflammasomes as regulators of mechano-immunity. EMBO Rep 2024; 25:21-30. [PMID: 38177903 PMCID: PMC10897344 DOI: 10.1038/s44319-023-00008-2] [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: 08/28/2023] [Revised: 10/25/2023] [Accepted: 11/10/2023] [Indexed: 01/06/2024] Open
Abstract
Mechano-immunity, the intersection between cellular or tissue mechanics and immune cell function, is emerging as an important factor in many inflammatory diseases. Mechano-sensing defines how cells detect mechanical changes in their environment. Mechano-response defines how cells adapt to such changes, e.g. form synapses, signal or migrate. Inflammasomes are intracellular immune sensors that detect changes in tissue and cell homoeostasis during infection or injury. We and others recently found that mechano-sensing of tissue topology (swollen tissue), topography (presence and distribution of foreign solid implant) or biomechanics (stiffness), alters inflammasome activity. Once activated, inflammasomes induce the secretion of inflammatory cytokines, but also change cellular mechanical properties, which influence how cells move, change their shape, and interact with other cells. When overactive, inflammasomes lead to chronic inflammation. This clearly places inflammasomes as important players in mechano-immunity. Here, we discuss a model whereby inflammasomes integrate pathogen- and tissue-injury signals, with changes in tissue mechanics, to shape the downstream inflammatory responses and allow cell and tissue mechano-adaptation. We will review the emerging evidence that supports this model.
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Affiliation(s)
| | - Clare E Bryant
- Department of Veterinary Medicine, University of Cambridge, Cambridge, Cambridgeshire, UK.
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3
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Loyo-Celis V, Patel D, Sanghvi S, Kaur K, Ponnalagu D, Zheng Y, Bindra S, Bhachu HR, Deschenes I, Gururaja Rao S, Singh H. Biophysical characterization of chloride intracellular channel 6 (CLIC6). J Biol Chem 2023; 299:105349. [PMID: 37838179 PMCID: PMC10641671 DOI: 10.1016/j.jbc.2023.105349] [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: 01/11/2023] [Revised: 09/27/2023] [Accepted: 09/30/2023] [Indexed: 10/16/2023] Open
Abstract
Chloride intracellular channels (CLICs) are a family of proteins that exist in soluble and transmembrane forms. The newest discovered member of the family CLIC6 is implicated in breast, ovarian, lung gastric, and pancreatic cancers and is also known to interact with dopamine-(D(2)-like) receptors. The soluble structure of the channel has been resolved, but the exact physiological role of CLIC6, biophysical characterization, and the membrane structure remain unknown. Here, we aimed to characterize the biophysical properties of this channel using a patch-clamp approach. To determine the biophysical properties of CLIC6, we expressed CLIC6 in HEK-293 cells. On ectopic expression, CLIC6 localizes to the plasma membrane of HEK-293 cells. We established the biophysical properties of CLIC6 by using electrophysiological approaches. Using various anions and potassium (K+) solutions, we determined that CLIC6 is more permeable to chloride-(Cl-) as compared to bromide-(Br-), fluoride-(F-), and K+ ions. In the whole-cell configuration, the CLIC6 currents were inhibited after the addition of 10 μM of IAA-94 (CLIC-specific blocker). CLIC6 was also found to be regulated by pH and redox potential. We demonstrate that the histidine residue at 648 (H648) in the C terminus and cysteine residue in the N terminus (C487) are directly involved in the pH-induced conformational change and redox regulation of CLIC6, respectively. Using qRT-PCR, we identified that CLIC6 is most abundant in the lung and brain, and we recorded the CLIC6 current in mouse lung epithelial cells. Overall, we have determined the biophysical properties of CLIC6 and established it as a Cl- channel.
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Affiliation(s)
- Veronica Loyo-Celis
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Devendra Patel
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Shridhar Sanghvi
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA; Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, Ohio, USA
| | - Kamalpreet Kaur
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Devasena Ponnalagu
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA; Department of Pharmacology, The University of Washington, Seattle, Washington, USA
| | - Yang Zheng
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Sahej Bindra
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Harmeet Rireika Bhachu
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Isabelle Deschenes
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | | | - Harpreet Singh
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA; Department of Molecular Cellular and Developmental Biology, The Ohio State University, Columbus, Ohio, USA.
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4
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Ott E, Hoff S, Indorf L, Ditengou FA, Müller J, Renschler G, Lienkamp SS, Kramer-Zucker A, Bergmann C, Epting D. A novel role for the chloride intracellular channel protein Clic5 in ciliary function. Sci Rep 2023; 13:17647. [PMID: 37848494 PMCID: PMC10582032 DOI: 10.1038/s41598-023-44235-y] [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: 12/05/2022] [Accepted: 10/05/2023] [Indexed: 10/19/2023] Open
Abstract
CLIC5 belongs to a family of ion channels with six members reported so far. In vertebrates, the CLIC5 gene encodes two different isoforms, CLIC5A and CLIC5B. In addition to its ion channel activity, there is evidence for further functions of CLIC5A, such as the remodeling of the actin cytoskeleton during the formation of a functional glomerulus in the vertebrate kidney. However, its specific role is still incompletely understood and a specific functional role for CLIC5B has not been described yet. Here we report our findings on the differential expression and functions of Clic5a and Clic5b during zebrafish kidney development. Whole-mount in situ hybridization studies revealed specific expression of clic5a in the eye and pronephric glomerulus, and clic5b is expressed in the gut, liver and the pronephric tubules. Clic5 immunostainings revealed that Clic5b is localized in the cilia. Whereas knockdown of Clic5a resulted in leakiness of the glomerular filtration barrier, Clic5b deficient embryos displayed defective ciliogenesis, leading to ciliopathy-associated phenotypes such as ventral body curvature, otolith deposition defects, altered left-right asymmetry and formation of hydrocephalus and pronephric cysts. In addition, Clic5 deficiency resulted in dysregulation of cilia-dependent Wnt signalling pathway components. Mechanistically, we identified a Clic5-dependent activation of the membrane-cytoskeletal linker proteins Ezrin/Radixin/Moesin (ERM) in the pronephric tubules of zebrafish. In conclusion, our in vivo data demonstrates a novel role for Clic5 in regulating essential ciliary functions and identified Clic5 as a positive regulator of ERM phosphorylation.
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Affiliation(s)
- Elisabeth Ott
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
| | - Sylvia Hoff
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
| | - Lara Indorf
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
| | - Franck Anicet Ditengou
- Bio Imaging Core Light Microscopy (BiMiC), Medical Faculty-Institute for Disease Modeling and Targeted Medicine (IMITATE), 79106, Freiburg, Germany
| | - Julius Müller
- Limbach Genetics, Medizinische Genetik Mainz, 55128, Mainz, Germany
| | - Gina Renschler
- Limbach Genetics, Medizinische Genetik Mainz, 55128, Mainz, Germany
| | - Soeren S Lienkamp
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
- Center for Biological Signaling Studies (BIOSS), 79104, Freiburg, Germany
| | - Albrecht Kramer-Zucker
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
| | - Carsten Bergmann
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany
- Limbach Genetics, Medizinische Genetik Mainz, 55128, Mainz, Germany
| | - Daniel Epting
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, 79106, Freiburg, Germany.
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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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6
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Chen GL, Li J, Zhang J, Zeng B. To Be or Not to Be an Ion Channel: Cryo-EM Structures Have a Say. Cells 2023; 12:1870. [PMID: 37508534 PMCID: PMC10378246 DOI: 10.3390/cells12141870] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/13/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
Ion channels are the second largest class of drug targets after G protein-coupled receptors. In addition to well-recognized ones like voltage-gated Na/K/Ca channels in the heart and neurons, novel ion channels are continuously discovered in both excitable and non-excitable cells and demonstrated to play important roles in many physiological processes and diseases such as developmental disorders, neurodegenerative diseases, and cancer. However, in the field of ion channel discovery, there are an unignorable number of published studies that are unsolid and misleading. Despite being the gold standard of a functional assay for ion channels, electrophysiological recordings are often accompanied by electrical noise, leak conductance, and background currents of the membrane system. These unwanted signals, if not treated properly, lead to the mischaracterization of proteins with seemingly unusual ion-conducting properties. In the recent ten years, the technical revolution of cryo-electron microscopy (cryo-EM) has greatly advanced our understanding of the structures and gating mechanisms of various ion channels and also raised concerns about the pore-forming ability of some previously identified channel proteins. In this review, we summarize cryo-EM findings on ion channels with molecular identities recognized or disputed in recent ten years and discuss current knowledge of proposed channel proteins awaiting cryo-EM analyses. We also present a classification of ion channels according to their architectures and evolutionary relationships and discuss the possibility and strategy of identifying more ion channels by analyzing structures of transmembrane proteins of unknown function. We propose that cross-validation by electrophysiological and structural analyses should be essentially required for determining molecular identities of novel ion channels.
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Affiliation(s)
- Gui-Lan Chen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Jian Li
- College of Pharmaceutical Sciences, Gannan Medical University, Ganzhou 341000, China
| | - Jin Zhang
- School of Basic Medical Sciences, Nanchang University, Nanchang 330031, China
| | - Bo Zeng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
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Ion Channel Involvement in Tumor Drug Resistance. J Pers Med 2022; 12:jpm12020210. [PMID: 35207698 PMCID: PMC8878471 DOI: 10.3390/jpm12020210] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/28/2022] [Accepted: 02/02/2022] [Indexed: 11/30/2022] Open
Abstract
Over 90% of deaths in cancer patients are attributed to tumor drug resistance. Resistance to therapeutic agents can be due to an innate property of cancer cells or can be acquired during chemotherapy. In recent years, it has become increasingly clear that regulation of membrane ion channels is an important mechanism in the development of chemoresistance. Here, we review the contribution of ion channels in drug resistance of various types of cancers, evaluating their potential in clinical management. Several molecular mechanisms have been proposed, including evasion of apoptosis, cell cycle arrest, decreased drug accumulation in cancer cells, and activation of alternative escape pathways such as autophagy. Each of these mechanisms leads to a reduction of the therapeutic efficacy of administered drugs, causing more difficulty in cancer treatment. Thus, targeting ion channels might represent a good option for adjuvant therapies in order to counteract chemoresistance development.
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Huang JJ, Lin J, Chen X, Zhu W. Identification of chloride intracellular channels as prognostic factors correlated with immune infiltration in hepatocellular carcinoma using bioinformatics analysis. Medicine (Baltimore) 2021; 100:e27739. [PMID: 34766585 PMCID: PMC10545300 DOI: 10.1097/md.0000000000027739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 09/21/2021] [Accepted: 10/22/2021] [Indexed: 12/28/2022] Open
Abstract
ABSTRACT Chloride intracellular channel (CLIC) proteins are novel Cl-channels with 6 family members (CLIC1-6) that are known to play crucial roles in multiple physiological functions, such as neurological, cardiovascular, pulmonary, and auditory functions, and in various malignancies, including hepatocellular carcinoma (HCC). However, considerable challenges exist in identifying appropriate CLICs as therapeutic target molecules and prognostic biomarkers for HCC because the transformation of soluble or integral membrane protein forms, and specific pharmacological agents (agonists and antagonists) for distinct CLICs remains enigmatic.To address this issue and the possible molecular basis and the signaling networks activated by CLICs in HCC, we examined the transcriptional, promoter methylation, DNA mutation, survival, and immune infiltration data of CLICs in patients with HCC using the ONCOMINE, UALCAN, GEPIA, cBioPortal, and TIMER databases.The data showed that the expression levels of CLIC family members were differed between tumor and normal tissues. High expression levels of CLIC1 and CLIC3 were associated with advanced cancer stage in HCC patients. Low CLIC1 expression was associated with a better overall survival (OS). The DNA methylation levels of the CLIC1-3 and CLIC5-6 promoters in tumor tissue with HCC were significantly lower in HCC tissues than in normal tissues. Patients with CLIC1 alterations had a shorter OS than patients with unaltered CLIC1. Moreover, the expression levels of CLICs correlated with the infiltration of 6 different immune cells (B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and dendritic cells).These results indicate that the increased mRNA expression and decreased promoter DNA methylation level of CLICs may play crucial roles in HCC tumorigenesis. The expression of CLIC family members was significantly correlated with the tumor immune status. High CLIC1 and CLIC3 expression levels could serve as biomarkers for identifying advanced-stage HCC. Moreover, a CLIC1 mutation rate of 18% was also observed and CLIC1 genetic alterations were significantly associated with lower OS in HCC patients.
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Affiliation(s)
- Juan-Jun Huang
- Department of Infectious Diseases, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou, Jiangxi, PR China
| | - Jing Lin
- Central Laboratory, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou, Jiangxi, PR China
| | - Xiaoli Chen
- Central Laboratory, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou, Jiangxi, PR China
| | - Wei Zhu
- Central Laboratory, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou, Jiangxi, PR China
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Abstract
Mitochondria have been recognized as key organelles in cardiac physiology and are potential targets for clinical interventions to improve cardiac function. Mitochondrial dysfunction has been accepted as a major contributor to the development of heart failure. The main function of mitochondria is to meet the high energy demands of the heart by oxidative metabolism. Ionic homeostasis in mitochondria directly regulates oxidative metabolism, and any disruption in ionic homeostasis causes mitochondrial dysfunction and eventually contractile failure. The mitochondrial ionic homeostasis is closely coupled with inner mitochondrial membrane potential. To regulate and maintain ionic homeostasis, mitochondrial membranes are equipped with ion transporting proteins. Ion transport mechanisms involving several different ion channels and transporters are highly efficient and dynamic, thus helping to maintain the ionic homeostasis of ions as well as their salts present in the mitochondrial matrix. In recent years, several novel proteins have been identified on the mitochondrial membranes and these proteins are actively being pursued in research for roles in the organ as well as organelle physiology. In this article, the role of mitochondrial ion channels in cardiac function is reviewed. In recent times, the major focus of the mitochondrial ion channel field is to establish molecular identities as well as assigning specific functions to them. Given the diversity of mitochondrial ion channels and their unique roles in cardiac function, they present novel and viable therapeutic targets for cardiac diseases.
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Affiliation(s)
- Harpreet Singh
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, Ohio
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10
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Turkewitz DR, Moghaddasi S, Alghalayini A, D'Amario C, Ali HM, Wallach M, Valenzuela SM. Comparative study of His- and Non-His-tagged CLIC proteins, reveals changes in their enzymatic activity. Biochem Biophys Rep 2021; 26:101015. [PMID: 34036185 PMCID: PMC8138732 DOI: 10.1016/j.bbrep.2021.101015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/15/2021] [Accepted: 05/02/2021] [Indexed: 10/29/2022] Open
Abstract
The chloride intracellular ion channel protein (CLIC) family are a unique set of ion channels that can exist as soluble and integral membrane proteins. New evidence has emerged that demonstrates CLICs' possess oxidoreductase enzymatic activity and may function as either membrane-spanning ion channels or as globular enzymes. To further characterize the enzymatic profile of members of the CLIC family and to expand our understanding of their functions, we expressed and purified recombinant CLIC1, CLIC3, and a non-functional CLIC1-Cys24A mutant using a Histidine tag, bacterial protein expression system. We demonstrate that the presence of the six-polyhistidine tag at the amino terminus of the proteins led to a decrease in their oxidoreductase enzymatic activity compared to their non-His-tagged counterparts, when assessed using 2-hydroxyethyl disulfide as a substrate. These results strongly suggest the six-polyhistidine tag alters CLIC's structure at the N-terminus, which also contains the enzyme active site. It also raises the need for caution in use of His-tagged proteins when assessing oxidoreductase protein enzymatic function.
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Affiliation(s)
- Daniel R. Turkewitz
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Saba Moghaddasi
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Amani Alghalayini
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
- ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology Sydney, NSW, 2007, Australia
| | - Claudia D'Amario
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Hala M. Ali
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Michael Wallach
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Stella M. Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia
- ARC Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL), Faculty of Science, University of Technology Sydney, NSW, 2007, Australia
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11
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Measurement of Oxidative Stress Markers In Vitro Using Commercially Available Kits. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/978-3-030-47318-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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12
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Ferofontov A, Vankova P, Man P, Giladi M, Haitin Y. Conserved cysteine dioxidation enhances membrane interaction of human Cl - intracellular channel 5. FASEB J 2020; 34:9925-9940. [PMID: 32725932 DOI: 10.1096/fj.202000399r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/21/2020] [Accepted: 04/30/2020] [Indexed: 11/11/2022]
Abstract
The human chloride intracellular channel (hCLIC) family is thought to transition between globular and membrane-associated forms by exposure of a hydrophobic surface. However, the molecular identity of this surface, and the triggering events leading to its exposure, remain elusive. Here, by combining biochemical and structural approaches, together with mass spectrometry (MS) analyses, we show that hCLIC5 is inherently flexible. X-ray crystallography revealed the existence of a globular conformation, while small-angle X-ray scattering showed additional elongated forms consisting of exposure of the conserved hydrophobic inter-domain interface to the bulk phase. Tryptophan fluorescence measurements demonstrated that the transition to the membrane-associated form is enhanced by the presence of oxidative environment and lipids. Using MS, we identified a dose-dependent oxidation of a highly conserved cysteine residue, known to play a key role in the structurally related omega-class of glutathione-S-transferases. Hydrogen/deuterium exchange MS analysis revealed that oxidation of this cysteine facilitates the exposure of the conserved hydrophobic inter-domain interface. Together, our results pinpoint an oxidation of a specific cysteine residue as a triggering mechanism initializing the molecular commitment for membrane interaction in the CLIC family.
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Affiliation(s)
- Alisa Ferofontov
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Pavla Vankova
- Division BioCeV, Institute of Microbiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petr Man
- Division BioCeV, Institute of Microbiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Moshe Giladi
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Yoni Haitin
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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13
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Zhang X, Mao F, Wong NK, Bao Y, Lin Y, Liu K, Li J, Xiang Z, Ma H, Xiao S, Zhang Y, Yu Z. CLIC2α Chloride Channel Orchestrates Immunomodulation of Hemocyte Phagocytosis and Bactericidal Activity in Crassostrea gigas. iScience 2020; 23:101328. [PMID: 32674055 PMCID: PMC7363696 DOI: 10.1016/j.isci.2020.101328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/02/2020] [Accepted: 06/26/2020] [Indexed: 02/07/2023] Open
Abstract
Chloride ion plays critical roles in modulating immunological interactions. Herein, we demonstrated that the anion channel CLIC2α mediates Cl− flux to regulate hemocytes functions in the Pacific oyster (Crassostrea gigas). Specifically, during infection by Vibrio parahemolyticus, chloride influx was activated following onset of phagocytosis. Phosphorylation of Akt was stimulated by Cl− ions entering host cells, further contributing to signal transduction regulating internalization of bacteria through the PI3K/Akt signaling pathway. Concomitantly, Cl− entered phagosomes, promoted the acidification and maturation of phagosomes, and contributed to production of HOCl to eradicate engulfed bacteria. Finally, genomic screening reveals CLIC2α as a major Cl− channel gene responsible for regulating Cl− influx in oysters. Knockdown of CLIC2α predictably impeded phagosome acidification and restricted bacterial killing in oysters. In conclusion, our work has established CLIC2α as a prominent regulator of Cl− influx and thus Cl− function in C. gigas in bacterial infection contexts. Influx of chloride ions is switched on during phagocytosis in oyster hemocytes PI3K/Akt signaling pathway mediates chloride-dependent activation of phagocytosis Cl− promotes phagosomal acidification and HOCl production CLIC2α is the principal chloride channel encoding gene within oyster genome
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Affiliation(s)
- Xiangyu Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fan Mao
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China
| | - Nai-Kei Wong
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; National Clinical Research Center for Infectious Diseases, Shenzhen Third People's Hospital, The Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, P. R. China
| | - Yongbo Bao
- Zhejiang Key Laboratory of Aquatic Germplasm Resources, College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, P. R. China
| | - Yue Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Kunna Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jun Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China
| | - Zhiming Xiang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China
| | - Haitao Ma
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China
| | - Shu Xiao
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China
| | - Yang Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China.
| | - Ziniu Yu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE), South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301, P. R. China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 510301, P. R. China.
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14
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Ponnalagu D, Singh H. Insights Into the Role of Mitochondrial Ion Channels in Inflammatory Response. Front Physiol 2020; 11:258. [PMID: 32327997 PMCID: PMC7160495 DOI: 10.3389/fphys.2020.00258] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/05/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are the source of many pro-inflammatory signals that cause the activation of the immune system and generate inflammatory responses. They are also potential targets of pro-inflammatory mediators, thus triggering a severe inflammatory response cycle. As mitochondria are a central hub for immune system activation, their dysfunction leads to many inflammatory disorders. Thus, strategies aiming at regulating mitochondrial dysfunction can be utilized as a therapeutic tool to cure inflammatory disorders. Two key factors that determine the structural and functional integrity of mitochondria are mitochondrial ion channels and transporters. They are not only important for maintaining the ionic homeostasis of the cell, but also play a role in regulating reactive oxygen species generation, ATP production, calcium homeostasis and apoptosis, which are common pro-inflammatory signals. The significance of the mitochondrial ion channels in inflammatory response is still not clearly understood and will need further investigation. In this article, we review the different mechanisms by which mitochondria can generate the inflammatory response as well as highlight how mitochondrial ion channels modulate these mechanisms and impact the inflammatory processes.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, United States
| | - Harpreet Singh
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Wexner Medical Center, Columbus, OH, United States
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15
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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: 70] [Impact Index Per Article: 17.5] [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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16
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Ponnalagu D, Hussain AT, Thanawala R, Meka J, Bednarczyk P, Feng Y, Szewczyk A, GururajaRao S, Bopassa JC, Khan M, Singh H. Chloride channel blocker IAA-94 increases myocardial infarction by reducing calcium retention capacity of the cardiac mitochondria. Life Sci 2019; 235:116841. [PMID: 31494173 PMCID: PMC7664129 DOI: 10.1016/j.lfs.2019.116841] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/28/2019] [Accepted: 09/04/2019] [Indexed: 01/14/2023]
Abstract
Indanyloxyacetic acid-94 (IAA-94), an intracellular chloride channel blocker, is shown to ablate cardioprotection rendered by ischemic preconditioning (IPC), N (6)-2-(4-aminophenyl) ethyladenosine or the PKC activator phorbol 12-myristate 13-acetate and cyclosporin A (CsA) in both ex-vivo and in-vivo ischemia-reperfusion (IR) injury. Thus signifying the role of the IAA-94 sensitive chloride channels in mediating cardio-protection upon IR injury. Although IAA-94 sensitive chloride currents are recorded in cardiac mitoplast, there is still a lack of understanding of the mechanism by which IAA-94 increases myocardial infarction (MI) by IR injury. Mitochondria are the key arbitrators of cell life and death pathways. Both oxidative stress and calcium overload in the mitochondria, elicit pathways resulting in the opening of mitochondrial permeability transition pore (mPTP) leading to cell death. Therefore, in this study we explored the role of IAA-94 in MI and in maintaining calcium retention capacity (CRC) of cardiac mitochondria after IR. IAA-94 inhibited the CRC of the isolated cardiac mitochondria in a concentration-dependent manner as measured spectrofluorimetrically using calcium green-5 N. Interestingly, IAA-94 did not change the mitochondrial membrane potential. Further, CsA a blocker of mPTP opening could not override the effect of IAA-94. We also showed for the first time that IAA-94 perfusion after ischemic event augments MI by reducing the CRC of mitochondria. To conclude, our results demonstrate that the mechanism of IAA-94 mediated cardio-deleterious effects is via modulating the mitochondria CRC, thereby playing a role in mPTP opening. These findings highlight new pharmacological targets, which can mediate cardioprotection from IR injury.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, United States of America.
| | - Ahmed Tafsirul Hussain
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America
| | - Rushi Thanawala
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America
| | - Jahnavi Meka
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America
| | - Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences - SGGW, Poland
| | - Yansheng Feng
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, TX 78229, United States of America
| | - Adam Szewczyk
- Department of Biochemistry, Nencki Institute of Experimental Biology, Poland
| | - Shubha GururajaRao
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, United States of America
| | - Jean C Bopassa
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center, San Antonio, TX 78229, United States of America
| | - Mahmood Khan
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, United States of America; Department of Emergency Medicine, The Ohio State University, Columbus, OH 43210, United States of America
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States of America; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, United States of America.
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17
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Ferofontov A, Strulovich R, Marom M, Giladi M, Haitin Y. Inherent flexibility of CLIC6 revealed by crystallographic and solution studies. Sci Rep 2018; 8:6882. [PMID: 29720717 PMCID: PMC5931990 DOI: 10.1038/s41598-018-25231-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/16/2018] [Indexed: 12/22/2022] Open
Abstract
Chloride intracellular channels (CLICs) are a family of unique proteins, that were suggested to adopt both soluble and membrane-associated forms. Moreover, following this unusual metamorphic change, CLICs were shown to incorporate into membranes and mediate ion conduction in vitro, suggesting multimerization upon membrane insertion. Here, we present a 1.8 Å resolution crystal structure of the CLIC domain of mouse CLIC6 (mCLIC6). The structure reveals a monomeric arrangement and shows a high degree of structural conservation with other CLICs. Small-angle X-ray scattering (SAXS) analysis of mCLIC6 demonstrated that the overall solution structure is similar to the crystallographic conformation. Strikingly, further analysis of the SAXS data using ensemble optimization method unveiled additional elongated conformations, elucidating high structural plasticity as an inherent property of the protein. Moreover, structure-guided perturbation of the inter-domain interface by mutagenesis resulted in a population shift towards elongated conformations of mCLIC6. Additionally, we demonstrate that oxidative conditions induce an increase in mCLIC6 hydrophobicity along with mild oligomerization, which was enhanced by the presence of membrane mimetics. Together, these results provide mechanistic insights into the metamorphic nature of mCLIC6.
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Affiliation(s)
- Alisa Ferofontov
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Roi Strulovich
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Milit Marom
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Moshe Giladi
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel
| | - Yoni Haitin
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 6997801, Israel. .,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel.
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18
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Gururaja Rao S, Ponnalagu D, Patel NJ, Singh H. Three Decades of Chloride Intracellular Channel Proteins: From Organelle to Organ Physiology. CURRENT PROTOCOLS IN PHARMACOLOGY 2018; 80:11.21.1-11.21.17. [PMID: 30040212 PMCID: PMC6060641 DOI: 10.1002/cpph.36] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Intracellular organelles are membranous structures central for maintaining cellular physiology and the overall health of the cell. To maintain cellular function, intracellular organelles are required to tightly regulate their ionic homeostasis. Any imbalance in ionic concentrations can disrupt energy production (mitochondria), protein degradation (lysosomes), DNA replication (nucleus), or cellular signaling (endoplasmic reticulum). Ionic homeostasis is also important for volume regulation of intracellular organelles and is maintained by cation and anion channels as well as transporters. One of the major classes of ion channels predominantly localized to intracellular membranes is chloride intracellular channel proteins (CLICs). They are non-canonical ion channels with six homologs in mammals, existing as either soluble or integral membrane protein forms, with dual functions as enzymes and channels. Provided in this overview is a brief introduction to CLICs, and a summary of recent information on their localization, biophysical properties, and physiological roles. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Shubha Gururaja Rao
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Neel J Patel
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania
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19
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Identification and Characterization of a Bacterial Homolog of Chloride Intracellular Channel (CLIC) Protein. Sci Rep 2017; 7:8500. [PMID: 28819106 PMCID: PMC5561075 DOI: 10.1038/s41598-017-08742-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/17/2017] [Indexed: 11/25/2022] Open
Abstract
Chloride intracellular channels (CLIC) are non-classical ion channels lacking a signal sequence for membrane targeting. In eukaryotes, they are implicated in cell volume regulation, acidification, and cell cycle. CLICs resemble the omega class of Glutathione S-transferases (GST), yet differ from them in their ability to form ion channels. They are ubiquitously found in eukaryotes but no prokaryotic homolog has been characterized. We found that indanyloxyacetic acid-94 (IAA-94), a blocker of CLICs, delays the growth of Escherichia coli. In silico analysis showed that the E. coli stringent starvation protein A (SspA) shares sequence and structural homology with CLICs. Similar to CLICs, SspA lacks a signal sequence but contains an omega GST fold. Electrophysiological analysis revealed that SspA auto-inserts into lipid bilayers and forms IAA-94-sensitive ion channels. Substituting the ubiquitously conserved residue leucine 29 to alanine in the pore-forming region increased its single-channel conductance. SspA is essential for cell survival during acid-induced stress, and we found that acidic pH increases the open probability of SspA. Further, IAA-94 delayed the growth of wild-type but not sspA null mutant E. coli. Our results for the first time show that CLIC-like proteins exist in bacteria in the form of SspA, forming functional ion channels.
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20
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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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21
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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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Abstract
Mitochondria are the "power house" of a cell continuously generating ATP to ensure its proper functioning. The constant production of ATP via oxidative phosphorylation demands a large electrochemical force that drives protons across the highly selective and low-permeable mitochondrial inner membrane. Besides the conventional role of generating ATP, mitochondria also play an active role in calcium signaling, generation of reactive oxygen species (ROS), stress responses, and regulation of cell-death pathways. Deficiencies in these functions result in several pathological disorders like aging, cancer, diabetes, neurodegenerative and cardiovascular diseases. A plethora of ion channels and transporters are present in the mitochondrial inner and outer membranes which work in concert to preserve the ionic equilibrium of a cell for the maintenance of cell integrity, in physiological as well as pathophysiological conditions. For, e.g., mitochondrial cation channels KATP and BKCa play a significant role in cardioprotection from ischemia-reperfusion injury. In addition to the cation channels, mitochondrial anion channels are equally essential, as they aid in maintaining electro-neutrality by regulating the cell volume and pH. This chapter focusses on the information on molecular identity, structure, function, and physiological relevance of mitochondrial chloride channels such as voltage dependent anion channels (VDACs), uncharacterized mitochondrial inner membrane anion channels (IMACs), chloride intracellular channels (CLIC) and the aspects of forthcoming chloride channels.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Room 8154, Mail Stop 488, Philadelphia, PA, 19102-1192, USA
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Room 8154, Mail Stop 488, Philadelphia, PA, 19102-1192, USA.
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23
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Neveu B, Spinella JF, Richer C, Lagacé K, Cassart P, Lajoie M, Jananji S, Drouin S, Healy J, Hickson GRX, Sinnett D. CLIC5: a novel ETV6 target gene in childhood acute lymphoblastic leukemia. Haematologica 2016; 101:1534-1543. [PMID: 27540136 PMCID: PMC5479611 DOI: 10.3324/haematol.2016.149740] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/11/2016] [Indexed: 01/13/2023] Open
Abstract
The most common rearrangement in childhood precursor B-cell acute lymphoblastic leukemia is the t(12;21)(p13;q22) translocation resulting in the ETV6-AML1 fusion gene. A frequent concomitant event is the loss of the residual ETV6 allele suggesting a critical role for the ETV6 transcriptional repressor in the etiology of this cancer. However, the precise mechanism through which loss of functional ETV6 contributes to disease pathogenesis is still unclear. To investigate the impact of ETV6 loss on the transcriptional network and to identify new transcriptional targets of ETV6, we used whole transcriptome analysis of both pre-B leukemic cell lines and patients combined with chromatin immunoprecipitation. Using this integrative approach, we identified 4 novel direct ETV6 target genes: CLIC5, BIRC7, ANGPTL2 and WBP1L To further evaluate the role of chloride intracellular channel protein CLIC5 in leukemogenesis, we generated cell lines overexpressing CLIC5 and demonstrated an increased resistance to hydrogen peroxide-induced apoptosis. We further described the implications of CLIC5's ion channel activity in lysosomal-mediated cell death, possibly by modulating the function of the transferrin receptor with which it colocalizes intracellularly. For the first time, we showed that loss of ETV6 leads to significant overexpression of CLIC5, which in turn leads to decreased lysosome-mediated apoptosis. Our data suggest that heightened CLIC5 activity could promote a permissive environment for oxidative stress-induced DNA damage accumulation, and thereby contribute to leukemogenesis.
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Affiliation(s)
- Benjamin Neveu
- CHU Sainte-Justine Research Center, Montreal, Canada
- Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Montreal, Canada
| | - Jean-François Spinella
- CHU Sainte-Justine Research Center, Montreal, Canada
- Molecular biology program, Faculty of Medicine, University of Montreal, Montreal, Canada
| | | | - Karine Lagacé
- CHU Sainte-Justine Research Center, Montreal, Canada
- Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Montreal, Canada
| | | | | | | | - Simon Drouin
- CHU Sainte-Justine Research Center, Montreal, Canada
| | - Jasmine Healy
- CHU Sainte-Justine Research Center, Montreal, Canada
| | - Gilles R X Hickson
- CHU Sainte-Justine Research Center, Montreal, Canada
- Department of Pathology and Cellular Biology, Faculty of Medicine, University of Montreal, Montreal, Canada
| | - Daniel Sinnett
- CHU Sainte-Justine Research Center, Montreal, Canada
- Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Montreal, Canada
- Department of Pediatrics, Faculty of Medicine, University of Montreal, Montreal, Canada
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24
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Ponnalagu D, Gururaja Rao S, Farber J, Xin W, Hussain AT, Shah K, Tanda S, Berryman M, Edwards JC, Singh H. Molecular identity of cardiac mitochondrial chloride intracellular channel proteins. Mitochondrion 2016; 27:6-14. [PMID: 26777142 DOI: 10.1016/j.mito.2016.01.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 12/08/2015] [Accepted: 01/07/2016] [Indexed: 01/08/2023]
Abstract
Emerging evidences demonstrate significance of chloride channels in cardiac function and cardioprotection from ischemia-reperfusion (IR) injury. Unlike mitochondrial potassium channels sensitive to calcium (BKCa) and ATP (KATP), molecular identity of majority of cardiac mitochondrial chloride channels located at the inner membrane is not known. In this study, we report the presence of unique dimorphic chloride intracellular channel (CLIC) proteins namely CLIC1, CLIC4 and CLIC5 as abundant CLICs in the rodent heart. Further, CLIC4, CLIC5, and an ortholog present in Drosophila (DmCLIC) localize to adult cardiac mitochondria. We found that CLIC4 is enriched in the outer mitochondrial membrane, whereas CLIC5 is present in the inner mitochondrial membrane. Also, CLIC5 plays a direct role in regulating mitochondrial reactive oxygen species (ROS) generation. Our study highlights that CLIC5 is localized to the cardiac mitochondria and directly modulates mitochondrial function.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Shubha Gururaja Rao
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Jason Farber
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Wenyu Xin
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Ahmed Tafsirul Hussain
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Kajol Shah
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Soichi Tanda
- Department of Biological Sciences, Ohio University, Athens, OH 45701, United States
| | - Mark Berryman
- Department of Biomedical Sciences, Ohio University, Athens, OH 45701, United States
| | - John C Edwards
- Division of Nephrology, St. Louis University, St. Louis, MO 63110, United States
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
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25
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Al Khamici H, Brown LJ, Hossain KR, Hudson AL, Sinclair-Burton AA, Ng JPM, Daniel EL, Hare JE, Cornell BA, Curmi PMG, Davey MW, Valenzuela SM. Members of the chloride intracellular ion channel protein family demonstrate glutaredoxin-like enzymatic activity. PLoS One 2015; 10:e115699. [PMID: 25581026 PMCID: PMC4291220 DOI: 10.1371/journal.pone.0115699] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/26/2014] [Indexed: 01/07/2023] Open
Abstract
The Chloride Intracellular Ion Channel (CLIC) family consists of six evolutionarily conserved proteins in humans. Members of this family are unusual, existing as both monomeric soluble proteins and as integral membrane proteins where they function as chloride selective ion channels, however no function has previously been assigned to their soluble form. Structural studies have shown that in the soluble form, CLIC proteins adopt a glutathione S-transferase (GST) fold, however, they have an active site with a conserved glutaredoxin monothiol motif, similar to the omega class GSTs. We demonstrate that CLIC proteins have glutaredoxin-like glutathione-dependent oxidoreductase enzymatic activity. CLICs 1, 2 and 4 demonstrate typical glutaredoxin-like activity using 2-hydroxyethyl disulfide as a substrate. Mutagenesis experiments identify cysteine 24 as the catalytic cysteine residue in CLIC1, which is consistent with its structure. CLIC1 was shown to reduce sodium selenite and dehydroascorbate in a glutathione-dependent manner. Previous electrophysiological studies have shown that the drugs IAA-94 and A9C specifically block CLIC channel activity. These same compounds inhibit CLIC1 oxidoreductase activity. This work for the first time assigns a functional activity to the soluble form of the CLIC proteins. Our results demonstrate that the soluble form of the CLIC proteins has an enzymatic activity that is distinct from the channel activity of their integral membrane form. This CLIC enzymatic activity may be important for protecting the intracellular environment against oxidation. It is also likely that this enzymatic activity regulates the CLIC ion channel function.
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Affiliation(s)
- Heba Al Khamici
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Louise J. Brown
- Department of Chemistry and Bimolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Khondker R. Hossain
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales 2234, Australia
| | - Amanda L. Hudson
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Alxcia A. Sinclair-Burton
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Jane Phui Mun Ng
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Elizabeth L. Daniel
- Department of Chemistry and Bimolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Joanna E. Hare
- Department of Chemistry and Bimolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Bruce A. Cornell
- Surgical Diagnostics, Roseville, Sydney, New South Wales 2069, Australia
| | - Paul M. G. Curmi
- School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia
- Centre for Applied Medical Research, St Vincent's Hospital, Sydney, New South Wales 2010, Australia
| | - Mary W. Davey
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Stella M. Valenzuela
- School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
- Centre for Health Technologies, University of Technology Sydney, Sydney, New South Wales 2007, Australia
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26
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Edelman A, Sallenave JM. Cystic fibrosis, a multi-systemic mucosal disease: 25 years after the discovery of CFTR. Int J Biochem Cell Biol 2014; 52:2-4. [PMID: 24735713 DOI: 10.1016/j.biocel.2014.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Aleksander Edelman
- INSERM, U1151, Paris, France; Faculté de Médecine, Université Paris Descartes, Paris, France
| | - Jean-Michel Sallenave
- INSERM, UMR1152, Paris, France; University Paris Diderot, Sorbonne Paris Cité, Paris, France.
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27
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Peter B, Polyansky AA, Fanucchi S, Dirr HW. A Lys-Trp cation-π interaction mediates the dimerization and function of the chloride intracellular channel protein 1 transmembrane domain. Biochemistry 2013; 53:57-67. [PMID: 24328417 DOI: 10.1021/bi401433f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chloride intracellular channel protein 1 (CLIC1) is a dual-state protein that can exist either as a soluble monomer or in an integral membrane form. The oligomerization of the transmembrane domain (TMD) remains speculative despite it being implicated in pore formation. The extent to which electrostatic and van der Waals interactions drive folding and association of the dimorphic TMD is unknown and is complicated by the requirement of interactions favorable in both aqueous and membrane environments. Here we report a putative Lys37-Trp35 cation-π interaction and show that it stabilizes the dimeric form of the CLIC1 TMD in membranes. A synthetic 30-mer peptide comprising a K37M TMD mutant was examined in 2,2,2-trifluoroethanol, sodium dodecyl sulfate micelles, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes using far-ultraviolet (UV) circular dichroism, fluorescence, and UV absorbance spectroscopy. Our data suggest that Lys37 is not implicated in the folding, stability, or membrane insertion of the TMD peptide. However, removal of this residue impairs the formation of dimers and higher-order oligomers. This is accompanied by a 30-fold loss of chloride influx activity, suggesting that dimerization modulates the rate of chloride conductance. We propose that, within membranes, individual TMD helices associate via a Lys37-mediated cation-π interaction to form active dimers. The latter findings are also supported by results of modeling a putative TMD dimer conformation in which Lys37 and Trp35 form cation-π pairs at the dimer interface. Dimeric helix bundles may then associate to form fully active ion channels. Thus, within a membrane-like environment, aromatic interactions involving a polar lysine side chain provide a thermodynamic driving force for helix-helix association.
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Affiliation(s)
- Bradley Peter
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand , Johannesburg 2050, South Africa
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28
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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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29
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Peter B, Ngubane NCML, Fanucchi S, Dirr HW. Membrane Mimetics Induce Helix Formation and Oligomerization of the Chloride Intracellular Channel Protein 1 Transmembrane Domain. Biochemistry 2013; 52:2739-49. [DOI: 10.1021/bi4002776] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Bradley Peter
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Nomxolisi Chloë Mina-Liz Ngubane
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Sylvia Fanucchi
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Heini W. Dirr
- Protein Structure-Function Research
Unit, School of
Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
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30
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Jiang L, Salao K, Li H, Rybicka JM, Yates RM, Luo XW, Shi XX, Kuffner T, Tsai VWW, Husaini Y, Wu L, Brown DA, Grewal T, Brown LJ, Curmi PMG, Breit SN. Intracellular chloride channel protein CLIC1 regulates macrophage function through modulation of phagosomal acidification. J Cell Sci 2012; 125:5479-88. [PMID: 22956539 PMCID: PMC3561857 DOI: 10.1242/jcs.110072] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2012] [Indexed: 02/02/2023] Open
Abstract
Intracellular chloride channel protein 1 (CLIC1) is a 241 amino acid protein of the glutathione S transferase fold family with redox- and pH-dependent membrane association and chloride ion channel activity. Whilst CLIC proteins are evolutionarily conserved in Metazoa, indicating an important role, little is known about their biology. CLIC1 was first cloned on the basis of increased expression in activated macrophages. We therefore examined its subcellular localisation in murine peritoneal macrophages by immunofluorescence confocal microscopy. In resting cells, CLIC1 is observed in punctate cytoplasmic structures that do not colocalise with markers for endosomes or secretory vesicles. However, when these macrophages phagocytose serum-opsonised zymosan, CLIC1 translocates onto the phagosomal membrane. Macrophages from CLIC1(-/-) mice display a defect in phagosome acidification as determined by imaging live cells phagocytosing zymosan tagged with the pH-sensitive fluorophore Oregon Green. This altered phagosomal acidification was not accompanied by a detectable impairment in phagosomal-lysosomal fusion. However, consistent with a defect in acidification, CLIC1(-/-) macrophages also displayed impaired phagosomal proteolytic capacity and reduced reactive oxygen species production. Further, CLIC1(-/-) mice were protected from development of serum transfer induced K/BxN arthritis. These data all point to an important role for CLIC1 in regulating macrophage function through its ion channel activity and suggest it is a suitable target for the development of anti-inflammatory drugs.
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Affiliation(s)
- Lele Jiang
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Kanin Salao
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Hui Li
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Joanna M. Rybicka
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Robin M. Yates
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Xu Wei Luo
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Xin Xin Shi
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Tamara Kuffner
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Vicky Wang-Wei Tsai
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Yasmin Husaini
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Liyun Wu
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - David A. Brown
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, NSW 2006, 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 and University of New South Wales, Sydney, NSW 2010, Australia
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
| | - Samuel N. Breit
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital and University of New South Wales, Sydney, NSW 2010, Australia
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31
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Abstract
Luminal acidification is of pivotal importance for the physiology of the secretory and endocytic pathways and its diverse trafficking events. Acidification by the proton-pumping V-ATPase requires charge compensation by counterion currents that are commonly attributed to chloride. The molecular identification of intracellular chloride transporters and the improvement of methodologies for measuring intraorganellar pH and chloride have facilitated the investigation of the physiology of vesicular chloride transport. New data question the requirement of chloride for pH regulation of various organelles and furthermore ascribe functions to chloride that are beyond merely electrically shunting the proton pump. This review surveys the currently established and proposed intracellular chloride transporters and gives an overview of membrane-trafficking steps that are affected by the perturbation of chloride transport. Finally, potential mechanisms of membrane-trafficking modulation by chloride are discussed and put into the context of organellar ion homeostasis in general.
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Affiliation(s)
- Tobias Stauber
- Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany.
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32
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Al‐Awqati Q, Beauwens R. Cellular Mechanisms of H
+
and HCO
3
−
transport in tight urinary epithelia. Compr Physiol 2011. [DOI: 10.1002/cphy.cp080108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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33
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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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Bradford EM, Miller ML, Prasad V, Nieman ML, Gawenis LR, Berryman M, Lorenz JN, Tso P, Shull GE. CLIC5 mutant mice are resistant to diet-induced obesity and exhibit gastric hemorrhaging and increased susceptibility to torpor. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1531-42. [PMID: 20357015 DOI: 10.1152/ajpregu.00849.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chloride intracellular channel 5 (CLIC5) and other CLIC isoforms have been implicated in a number of biological processes, but their specific functions are poorly understood. The association of CLIC5 with ezrin and the actin cytoskeleton led us to test its possible involvement in gastric acid secretion. Clic5 mutant mice exhibited only a minor reduction in acid secretion, Clic5 mRNA was expressed at only low levels in stomach, and Clic5 mutant parietal cells were ultrastructurally normal, negating the hypothesis that CLIC5 plays a major role in acid secretion. However, the mutants exhibited gastric hemorrhaging in response to fasting, reduced monocytes and granulocytes suggestive of immune dysfunction, behavioral and social disorders suggestive of neurological dysfunction, and evidence of a previously unidentified metabolic defect. Wild-type and mutant mice were maintained on normal and high-fat diets; plasma levels of various hormones, glucose, and lipids were determined; and body composition was studied by quantitative magnetic resonance imaging. Clic5 mutants were lean, hyperphagic, and highly resistant to diet-induced obesity. Plasma insulin and glucose levels were reduced, and leptin levels were very low; however, plasma triglycerides, cholesterol, phospholipids, and fatty acids were normal. Indirect calorimetry revealed increased peripheral metabolism and greater reliance on carbohydrate metabolism. Because Clic5 mutants were unable to maintain energy reserves, they also exhibited increased susceptibility to fasting-induced torpor, as indicated by telemetric measurements showing episodes of reduced body temperature and heart rate. These data reveal a requirement for CLIC5 in the maintenance of normal systemic energy metabolism.
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Affiliation(s)
- Emily M Bradford
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, OH 45267-0524, USA
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35
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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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36
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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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37
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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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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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Singh H, Ashley RH. CLIC4 (p64H1) and its putative transmembrane domain form poorly selective, redox-regulated ion channels. Mol Membr Biol 2009; 24:41-52. [PMID: 17453412 DOI: 10.1080/09687860600927907] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Despite being synthesized in the cytosol without a leader sequence, the soluble 253-residue mammalian protein CLIC4 (Chloride Intracellular Channel 4, or p64H1), a structural homologue of Omega-type glutathione-S-transferase, autoinserts into membranes to form an integral membrane protein with ion channel activity. A predicted transmembrane domain (TMD) near the N-terminus of CLIC4 could mediate membrane insertion, and contribute to oligomeric pores, with minimal reorganization of the soluble protein structure. We tested this idea by reconstituting recombinant CLIC4 in planar bilayers containing phosphatidyethanolamine, phosphatidylserine and cholesterol, recording ion channels with a maximum conductance of approximately 15 pS in KCl under both oxidizing and reducing conditions. The channels discriminated poorly between anions and cations, incompatible with the current "CLIC" nomenclature, and their conductance was modified by the trans (external or luminal) redox potential, as previously observed for CLIC1. We then reconstituted a truncated version of the protein, limited to the first 61 residues containing the predicted TMD. This included a single trans cysteine residue in the putative pore-forming subunits, at the external entrance to the pore. The truncated protein formed non-selective channels with a reduced conductance, but they retained their trans-redox sensitivity, and could still be blocked or inactivated by trans (not cis) thiol-reative dithiobisnitrobenzoic acid. We suggest that oligomers containing the putative TMD are essential components of the CLIC4 pore. However, the pore is inherently non-selective, and any ionic selectivity in CLIC4 (and other membrane CLICs) may be attributable to other regions of the protein, including the channel vestibules.
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Affiliation(s)
- Harpreet Singh
- Biomedical Sciences, College of Medicine, University of Edinburgh, Edinburgh, UK
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Littler DR, Harrop SJ, Brown LJ, Pankhurst GJ, Mynott AV, Luciani P, Mandyam RA, Mazzanti M, Tanda S, Berryman MA, Breit SN, Curmi PMG. Comparison of vertebrate and invertebrate CLIC proteins: The crystal structures ofCaenorhabditis elegans EXC-4 andDrosophila melanogaster DmCLIC. Proteins 2008; 71:364-78. [DOI: 10.1002/prot.21704] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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41
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Berry KL, Hobert O. Mapping Functional Domains of Chloride Intracellular Channel (CLIC) Proteins in Vivo. J Mol Biol 2006; 359:1316-33. [PMID: 16737711 DOI: 10.1016/j.jmb.2006.04.046] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 04/06/2006] [Accepted: 04/20/2006] [Indexed: 10/24/2022]
Abstract
Chloride intracellular channel (CLIC) proteins are small proteins distantly related to the omega family of glutathione S-transferases (GSTs). CLIC proteins are expressed in a wide variety of tissues in multicellular organisms and are targeted to specific cellular membranes. Members of this family are capable in vitro of changing conformation from a globular, soluble state to a membrane-inserted state in which they provide chloride conductance. The structural basis for in vivo CLIC protein function, however, is not well understood. We have mapped the functional domains of CLIC family members using an in vivo assay for membrane localization and function of CLIC proteins in the nematode Caenorhabditis elegans. A<70 amino acid N-terminal domain is a key determinant of membrane localization and function of invertebrate CLIC proteins. This domain, which we term the ''PTM'' domain, named after an amphipathic putative transmembrane helix contained within it, directs distinct C. elegans CLIC homologs to distinct subcellular membranes. We find that within the PTM region, the cysteine residues required for GST-type activity are unnecessary for invertebrate CLIC function, but that specific residues within the proposed transmembrane helix are necessary for correct targeting and protein function. We find that among all tested invertebrate CLIC proteins, function appears to be completely conserved despite striking differences in the charged residues contained within the amphipathic helix. This indicates that these residues do not contribute to anion selectivity as previously suggested. We find that outside the PTM region, the remaining three-quarters of CLIC protein sequence is functionally equivalent not only among vertebrate and invertebrate CLIC proteins, but also among the more distantly related GST-omega and GST-sigma proteins. The PTM region thus provides both targeting information and CLIC functional specificity, possibly adapting GST-type proteins to function as ion channels.
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Affiliation(s)
- Katherine L Berry
- Department of Biochemistry and Molecular Biophysics Howard Hughes Medical Institute, Columbia University Medical Center, New York, NY 10032, USA
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42
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Board PG, Coggan M, Watson S, Gage PW, Dulhunty AF. CLIC-2 modulates cardiac ryanodine receptor Ca2+ release channels. Int J Biochem Cell Biol 2004; 36:1599-612. [PMID: 15147738 DOI: 10.1016/j.biocel.2004.01.026] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Accepted: 01/14/2004] [Indexed: 10/26/2022]
Abstract
We have examined the biochemical and functional properties of the recently identified, uncharacterised CLIC-2 protein. Sequence alignments showed that CLIC-2 has a high degree of sequence similarity with CLIC-1 and some similarity to the omega class of glutathione transferases (GSTO). A homology model of CLIC-2 based on the crystal structure of CLIC-1 suggests that CLIC-2 belongs to the GST structural family but, unlike the GSTs, CLIC-2 exists as a monomer. It also has an unusual enzyme activity profile. While the CXXC active site motif is conserved between CLIC-2 and the glutaredoxins, no thiol transferase activity was detected. In contrast, low glutathione peroxidase activity was recorded. CLIC-2 was found to be widely distributed in tissues including heart and skeletal muscle. Functional studies showed that CLIC-2 inhibited cardiac ryanodine receptor Ca2+ release channels in lipid bilayers when added to the cytoplasmic side of the channels and inhibited Ca2+ release from cardiac sarcoplasmic reticulum vesicles. The inhibition of RyR channels was reversed by removing CLIC-2 from the solution or by adding an anti-CLIC-2 antibody. The results suggest that one function of CLIC-2 might be to limit Ca2+ release from internal stores in cells.
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Affiliation(s)
- Philip G Board
- Division of Molecular Bioscience, John Curtin School of Medical Research, The Australian National University, P.O. Box 334, Canberra, ACT 2601, Australia.
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Berryman M, Bruno J, Price J, Edwards JC. CLIC-5A functions as a chloride channel in vitro and associates with the cortical actin cytoskeleton in vitro and in vivo. J Biol Chem 2004; 279:34794-801. [PMID: 15184393 DOI: 10.1074/jbc.m402835200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CLIC-5A is a member of the chloride intracellular channel protein family, which is comprised of six related human genes encoding putative chloride channels. In this study, we found that reconstitution of purified recombinant CLIC-5A into artificial liposomes resulted in a dose-dependent chloride efflux that was sensitive to the chloride channel blocker IAA-94. CLIC-5A was originally isolated as a component of an ezrin-containing cytoskeletal complex from human placental microvilli. Here we show that similar protein complexes can be isolated using either immobilized CLIC-5A or the C-terminal F-actin-binding domain of ezrin and that actin polymerization is required for de novo assembly of these complexes. To investigate the behavior of CLIC-5A in vivo, JEG-3 placental choriocarcinoma cells were stably transfected with epitope-tagged CLIC-5A. In fixed cells, CLIC-5A displayed a polarized distribution and colocalized with ezrin in apical microvilli. Microvillar localization of CLIC-5A was retained after Triton X-100 extraction and was disrupted by treatment with latrunculin B. In transient transfections assays, we mapped a region between residues 20 and 54 of CLIC-5A that is required for targeting of CLIC-5A to microvilli in JEG-3 cells. Interestingly, expression of CLIC-5A in JEG-3 cells did not enhance the rate of iodide efflux in intact cells, suggesting that if CLIC-5A is a chloride channel, its channel activity may be restricted to intracellular membrane compartments in these cells. Regardless of its role in ion transport, CLIC-5A, like ezrin, may play an important role in the assembly or maintenance of F-actin-based structures at the cell cortex.
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Affiliation(s)
- Mark Berryman
- Department of Biomedical Sciences, Ohio University College of Osteopathic Medicine and the Molecular and Cellular Biology Program, Athens, OH 45701, USA.
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Berry KL, Bülow HE, Hall DH, Hobert O. A C. elegans CLIC-like protein required for intracellular tube formation and maintenance. Science 2004; 302:2134-7. [PMID: 14684823 DOI: 10.1126/science.1087667] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Caenorhabditis elegans excretory canal is composed of a single elongated and branched cell that is tunneled by an inner lumen of apical character. Loss of the exc-4 gene causes a cystic enlargement of this intracellular tube. exc-4 encodes a member of the chloride intracellular channel (CLIC) family of proteins. EXC-4 protein localizes to various tubular membranes in distinct cell types, including the lumenal membrane of the excretory tubes. A conserved 55-amino acid domain enables EXC-4 translocation from the cytosol to the lumenal membrane. The tubular architecture of this membrane requires EXC-4 for both its formation and maintenance.
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Affiliation(s)
- Katherine L Berry
- Department of Biochemistry and Molecular Biophysics, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA
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Arnould T, Mercy L, Houbion A, Vankoningsloo S, Renard P, Pascal T, Ninane N, Demazy C, Raes M. mtCLIC is up-regulated and maintains a mitochondrial membrane potential in mtDNA-depleted L929 cells. FASEB J 2003; 17:2145-7. [PMID: 12958156 DOI: 10.1096/fj.03-0075fje] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To explain why mitochondrial DNA (mtDNA)-depleted or rho0 cells still keep a mitochondrial membrane potential (Delta(psi)m) in the absence of respiration, several hypotheses have been proposed. The principal and well accepted one involves a reverse of action for ANT combined to F1-ATPase activity. However, the existence of other putative electrogenic channels has been speculated. Here, using mRNA differential display reverse transcriptase-polymerase chain reaction on L929 mtDNA-depleted cells, we identified mtCLIC as a differentially expressed gene in cells deprived from mitochondrial ATP production. Mitochondrial chloride intracellular channel (mtCLIC), a member of a recently discovered and expanding family of chloride intracellular channels, is up-regulated in mtDNA-depleted and rho0 cells. We showed that its expression is dependent on CREB and p53 and is sensitive to calcium and tumor necrosis factor alpha. Interestingly, up- or down-regulation of mtCLIC protein expression changes Delta(psi)m whereas the chloride channel inhibitor NPPB reduces the Delta(psi)m in mtDNA-depleted L929 cells, measured with the fluorescent probe rhodamine 123. Finally, we demonstrated that purified mitochondria from mtDNA-depleted cells incorporate, in a NPPB-sensitive manner, more 36chloride than parental mitochondria. These findings suggest that mtCLIC could be involved in mitochondrial membrane potential generation in mtDNA-depleted cells, a feature required to prevent apoptosis and to drive continuous protein import into mitochondria.
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Affiliation(s)
- T Arnould
- Laboratoire de Biochimie et Biologie Cellulaire, University of Namur (F.U.N.D.P), 61 rue de Bruxelles, 5000 Namur, Belgium.
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Berryman MA, Goldenring JR. CLIC4 is enriched at cell-cell junctions and colocalizes with AKAP350 at the centrosome and midbody of cultured mammalian cells. ACTA ACUST UNITED AC 2003; 56:159-72. [PMID: 14569596 DOI: 10.1002/cm.10141] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
CLIC4 is a member of the chloride intracellular channel (CLIC) protein family whose principal cellular functions are poorly understood. Recently, we demonstrated that several CLIC proteins, including CLIC4, interact with AKAP350. AKAP350 is concentrated at the Golgi apparatus, centrosome, and midbody and acts as a scaffolding protein for several protein kinases and phosphatases. In this report, we show that endogenous CLIC4 and AKAP350 colocalize at the centrosome and midbody of cultured cells by immunofluorescence microscopy. Unlike AKAP350, CLIC4 is not enriched in the Golgi apparatus but is enriched in mitochondria, actin-based structures at the cell cortex, and the nuclear matrix, indicating that CLIC4-AKAP350 interactions are regulated at specific subcellular sites in vivo. In addition to the centrosome and midbody, CLIC4 colocalizes with AKAP350 and the tight junction protein ZO-1 in the apical region of polarized epithelial cells, suggesting that CLIC4 may play a role in maintaining apical-basolateral membrane polarity during mitosis and cytokinesis. Biochemical studies show that CLIC4 behaves mainly as a soluble cytosolic protein and can associate with proteins of the microtubule cytoskeleton. The localization of CLIC4 to the cortical actin cytoskeleton and its association with AKAP350 at the centrosome and midbody suggests that CLIC4 may be important for regulating cytoskeletal organization during the cell cycle. These findings lead to the conclusion that CLIC4 and possibly other CLIC proteins have alternate cellular functions that are distinct from their proposed roles as chloride channels.
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Affiliation(s)
- Mark A Berryman
- Department of Biomedical Sciences, Molecular and Cellular Biology Program, Ohio University College of Osteopathic Medicine, Athens, OH 45701, USA.
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Ashley RH. Challenging accepted ion channel biology: p64 and the CLIC family of putative intracellular anion channel proteins (Review). Mol Membr Biol 2003; 20:1-11. [PMID: 12745921 DOI: 10.1080/09687680210042746] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Parchorin, p64 and the related chloride intracellular channel (CLIC) proteins are widely expressed in multicellular organisms and have emerged as candidates for novel, auto-inserting, self-assembling intracellular anion channels involved in a wide variety of fundamental cellular events including regulated secretion, cell division and apoptosis. Although the mammalian phosphoproteins p64 and parchorin (49 and 65K, respectively) have only been indirectly implicated in anion channel activity, two CLIC proteins (CLIC1 and CLIC4, 27 and 29K, respectively) appear to be essential molecular components of anion channels, and CLIC1 can form anion channels in planar lipid bilayers in the absence of other cellular proteins. However, these putative ion channel proteins are controversial because they exist in both soluble and membrane forms, with at least one transmembrane domain. Even more surprisingly, soluble CLICs share the same glutaredoxin fold as soluble omega class glutathione-S-transferases. Working out how these ubiquitous, soluble proteins unfold, insert into membranes and then refold to form integral membrane proteins, and how cells control this potentially dangerous process and make use of the associated ion channels, are challenging prospects. Critical to this future work is the need for better characterization of membrane topology, careful functional analysis of reconstituted and native channels, including their conductances and selectivities, and detailed structure/function studies including targeted mutagenesis to investigate the structure of the putative pore, the role of protein phosphorylation and the role of conserved cysteine residues.
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Affiliation(s)
- R H Ashley
- Department of Biomedical Sciences, University of Edinburgh, UK.
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48
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Proutski I, Karoulias N, Ashley RH. Overexpressed chloride intracellular channel protein CLIC4 (p64H1) is an essential component of novel plasma membrane anion channels. Biochem Biophys Res Commun 2002; 297:317-22. [PMID: 12237120 DOI: 10.1016/s0006-291x(02)02199-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chloride intracellular channel protein CLIC4 is a putative organellar anion channel or channel regulator with an unusual dual cytoplasmic and integral membrane localisation. To investigate its contribution to cellular anion channel activity, the protein was overexpressed in stably transfected HEK-293 cells. Patch-clamp recording revealed CLIC4-associated indanyloxyacetic acid-sensitive (IC(50) approximately 100 microM) plasma membrane currents showing mild outward rectification, and novel low conductance (approximately 1pS) CLIC4-associated anion channels were resolved at the single-channel level. The CLIC4-associated channels were inhibited by anti-CLIC4 antibodies, including a monoclonal antibody directed against a FLAG epitope fused to the C-terminus of CLIC4, but only when these were applied to the cytoplasmic (not the external) face of the membrane. CLIC4 is thus an essential molecular component of novel cellular anion channels and the C-terminus of the integral membrane form of CLIC4 is cytoplasmic.
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Affiliation(s)
- I Proutski
- Department of Biomedical Sciences, University of Edinburgh, UK
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49
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Thévenod F. Ion channels in secretory granules of the pancreas and their role in exocytosis and release of secretory proteins. Am J Physiol Cell Physiol 2002; 283:C651-72. [PMID: 12176723 DOI: 10.1152/ajpcell.00600.2001] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Regulated secretion in exocrine and neuroendocrine cells occurs through exocytosis of secretory granules and the subsequent release of stored small molecules and proteins. The introduction of biophysical techniques with high temporal and spatial resolution, and the identification of Ca(2+)-dependent and -independent "docking" and "fusion" proteins, has greatly enhanced our understanding of exocytosis. The cloning of families of ion channel proteins, including intracellular ion channels, has also revived interest in the role of secretory granule ion channels in exocytotic secretion. Thus secretory granules of pancreatic acinar cell express a ClC-2 Cl(-) channel, a HCO-permeable member of the CLCA Ca(2+)-dependent anion channel family, and a KCNQ1 K(+) channel. Evidence suggests that these channels may facilitate the release of digestive enzymes and/or prevent exocytosed granules from collapsing during "kiss and run" recycling. In pancreatic beta-cells, a granular ClC-3 Cl(-) channel provides a shunt pathway for a vacuolar-type H(+)-ATPase. Acidification "primes" the granules for Ca(2+)-dependent exocytosis and release of insulin. In summary, secretory granules are equipped with specific sets of ion channels, which modulate regulated exocytosis and the release of macromolecules. These channels could represent excellent targets for therapeutic interventions to control exocytotic secretion in relevant diseases, such as pancreatitis, cystic fibrosis, or diabetes mellitus.
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Affiliation(s)
- Frank Thévenod
- School of Biological Sciences, University of Manchester, United Kingdom.
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50
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Rønnov-Jessen L, Villadsen R, Edwards JC, Petersen OW. Differential expression of a chloride intracellular channel gene, CLIC4, in transforming growth factor-beta1-mediated conversion of fibroblasts to myofibroblasts. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 161:471-80. [PMID: 12163372 PMCID: PMC1850723 DOI: 10.1016/s0002-9440(10)64203-4] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Conversion of fibroblasts into myofibroblasts as mediated by transforming growth factor-beta1 (TGF-beta1) is the most prominent stromal reaction to a number of epithelial lesions including breast cancer. To identify genes which are regulated during this process, the mRNA profiles from primary breast fibroblasts treated with or without TGF-beta1 were analyzed by differential display. Ninety-five differentially expressed transcripts were PCR-cloned and sequenced, and 28 clones were selected for verification in a hybridization array. By use of gene-specific sequence tags, nine differentially expressed genes were identified. One of the clones, identified as CLIC4, a member of the CLIC family of chloride channels, was up-regulated more than 16 times in myofibroblasts and was therefore chosen for further analysis. Using RT-PCR, comparison with CLIC1, CLIC2, CLIC3, and CLIC5 demonstrated that CLIC4 was unique by being up-regulated by TGF-beta1 in myofibroblasts. Immunohistochemistry showed a hitherto unknown, distinctive pattern of CLIC4 expression in breast stroma. Whereas normal breast fibroblasts were devoid of CLIC4 protein expression, myofibroblasts of breast carcinomas were strongly CLIC4-positive. The functional significance of CLIC4 was analyzed in MEF/3T3 fibroblasts by conditional expression using the tetracycline-repressive gene regulation system. In a migration assay, we found that CLIC4 inhibited cell motility by 27%. These results suggest that CLIC4 is differentially regulated in fibroblasts and that its expression contributes to a collective stationary myofibroblast phenotype.
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Affiliation(s)
- Lone Rønnov-Jessen
- Zoophysiological Laboratory, the August Krogh Institute, Copenhagen, Denmark.
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