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Morse J, Wang D, Mei S, Whitham D, Hladun C, Darie CC, Sintim HO, Wang M, Leung K. Chloride Homeostasis Regulates cGAS-STING Signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588475. [PMID: 38645072 PMCID: PMC11030317 DOI: 10.1101/2024.04.08.588475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
The cGAS-STING signaling pathway has emerged as a key mediator of inflammation. However, the roles of chloride homeostasis on this pathway are unclear. Here, we uncovered a correlation between chloride homeostasis and cGAS-STING signaling. We found that dysregulation of chloride homeostasis attenuates cGAS-STING signaling in a lysosome-independent manner. Treating immune cells with chloride channel inhibitors attenuated 2'3'-cGAMP production by cGAS and also suppressed STING polymerization, leading to reduced cytokine production. We also demonstrate that non-selective chloride channel blockers can suppress the NPC1 deficiency-induced, hyper-activated STING signaling in skin fibroblasts derived from Niemann Pick disease type C (NPC) patients. Our findings reveal that chloride homeostasis majorly affects cGAS-STING pathway and suggest a provocative strategy to dampen STING-mediated inflammation via targeting chloride channels.
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Affiliation(s)
- Jared Morse
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Danna Wang
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Serena Mei
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Danielle Whitham
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Colby Hladun
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Costel C. Darie
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - Herman O. Sintim
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Modi Wang
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
| | - KaHo Leung
- Department of Chemistry & Biomolecular Science, Clarkson University, NY, 13676, United States
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2
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Rashid MU, Coombs KM. Chloride Intracellular Channel Protein 1 (CLIC1) Is a Critical Host Cellular Factor for Influenza A Virus Replication. Viruses 2024; 16:129. [PMID: 38257829 PMCID: PMC10819074 DOI: 10.3390/v16010129] [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: 11/25/2023] [Revised: 01/10/2024] [Accepted: 01/13/2024] [Indexed: 01/24/2024] Open
Abstract
(1) Background: Influenza A Virus (IAV) uses host cellular proteins during replication in host cells. IAV infection causes elevated expression of chloride intracellular channel protein 1 (CLIC1) in lung epithelial cells, but the importance of this protein in IAV replication is unknown. (2) In this study, we determined the role of CLIC1 in IAV replication by investigating the effects of CLIC1 knockdown (KD) on IAV viral protein translation, genomic RNA transcription, and host cellular proteome dysregulation. (3) Results: CLIC1 KD in A549 human lung epithelial cells resulted in a significant decrease in progeny supernatant IAV, but virus protein expression was unaffected. However, a significantly larger number of viral RNAs accumulated in CLIC1 KD cells. Treatment with a CLIC1 inhibitor also caused a significant reduction in IAV replication, suggesting that CLIC1 is an important host factor in IAV replication. SomaScan®, which measures 1322 proteins, identified IAV-induced dysregulated proteins in wild-type cells and in CLIC1 KD cells. The expression of 116 and 149 proteins was significantly altered in wild-type and in CLIC1 KD cells, respectively. A large number of the dysregulated proteins in CLIC1 KD cells were associated with cellular transcription and predicted to be inhibited during IAV replication. (4) Conclusions: This study suggests that CLIC1 is involved in later stages of IAV replication. Further investigation should clarify mechanism(s) for the development of anti-IAV drugs targeting CLIC1 protein.
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Affiliation(s)
- Mahamud-ur Rashid
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Room 543 Basic Medical Sciences Building, 745 Bannatyne Avenue, Winnipeg, MB R3E OJ9, Canada
- Manitoba Centre for Proteomics and Systems Biology, Room 799, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
| | - Kevin M. Coombs
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Room 543 Basic Medical Sciences Building, 745 Bannatyne Avenue, Winnipeg, MB R3E OJ9, Canada
- Manitoba Centre for Proteomics and Systems Biology, Room 799, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
- Children’s Hospital Research Institute of Manitoba, Room 513, John Buhler Research Centre, 715 McDermot Avenue, Winnipeg, MB R3E 3P4, Canada
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3
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Alghalayini A, Hossain KR, Moghaddasi S, Turkewitz DR, D’Amario C, Wallach M, Valenzuela SM. In Vitro Enzymatic Studies Reveal pH and Temperature Sensitive Properties of the CLIC Proteins. Biomolecules 2023; 13:1394. [PMID: 37759794 PMCID: PMC10526857 DOI: 10.3390/biom13091394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/09/2023] [Accepted: 09/10/2023] [Indexed: 09/29/2023] Open
Abstract
Chloride intracellular ion channel (CLIC) proteins exist as both soluble and integral membrane proteins, with CLIC1 capable of shifting between two distinct structural conformations. New evidence has emerged indicating that members of the CLIC family act as moonlighting proteins, referring to the ability of a single protein to carry out multiple functions. In addition to their ion channel activity, CLIC family members possess oxidoreductase enzymatic activity and share significant structural and sequence homology, along with varying overlaps in their tissue distribution and cellular localization. In this study, the 2-hydroxyethyl disulfide (HEDS) assay system was used to characterize kinetic properties, as well as the temperature and pH profiles of three CLIC protein family members (CLIC1, CLIC3, CLIC4). We also assessed the effects of the drugs rapamycin and amphotericin B, on the three CLIC proteins' enzymatic activity in the HEDS assay. Our results demonstrate CLIC1 to be highly heat-sensitive, with optimal enzymatic activity observed at neutral pH7 and at a temperature of 37 °C, while CLIC3 had higher oxidoreductase activity in more acidic pH5 and was found to be relatively heat stable. CLIC4, like CLIC1, was temperature sensitive with optimal enzymatic activity observed at 37 °C; however, it showed optimal activity in more alkaline conditions of pH8. Our current study demonstrates individual differences in the enzymatic activity between the three CLIC proteins, suggesting each CLIC protein is likely regulated in discrete ways, involving changes in the subcellular milieu and microenvironment.
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Affiliation(s)
- Amani Alghalayini
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Khondker Rufaka Hossain
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Saba Moghaddasi
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Daniel R. Turkewitz
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Claudia D’Amario
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Michael Wallach
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
| | - Stella M. Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia; (A.A.); (K.R.H.); (S.M.); (D.R.T.); (C.D.); (M.W.)
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL), Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
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4
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Yadav GP, Wang H, Ouwendijk J, Cross S, Wang Q, Qin F, Verkade P, Zhu MX, Jiang QX. Chromogranin B (CHGB) is dimorphic and responsible for dominant anion channels delivered to cell surface via regulated secretion. Front Mol Neurosci 2023; 16:1205516. [PMID: 37435575 PMCID: PMC10330821 DOI: 10.3389/fnmol.2023.1205516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/26/2023] [Indexed: 07/13/2023] Open
Abstract
Regulated secretion is conserved in all eukaryotes. In vertebrates granin family proteins function in all key steps of regulated secretion. Phase separation and amyloid-based storage of proteins and small molecules in secretory granules require ion homeostasis to maintain their steady states, and thus need ion conductances in granule membranes. But granular ion channels are still elusive. Here we show that granule exocytosis in neuroendocrine cells delivers to cell surface dominant anion channels, to which chromogranin B (CHGB) is critical. Biochemical fractionation shows that native CHGB distributes nearly equally in soluble and membrane-bound forms, and both reconstitute highly selective anion channels in membrane. Confocal imaging resolves granular membrane components including proton pumps and CHGB in puncta on the cell surface after stimulated exocytosis. High pressure freezing immuno-EM reveals a major fraction of CHGB at granule membranes in rat pancreatic β-cells. A cryo-EM structure of bCHGB dimer of a nominal 3.5 Å resolution delineates a central pore with end openings, physically sufficient for membrane-spanning and large single channel conductance. Together our data support that CHGB-containing (CHGB+) channels are characteristic of regulated secretion, and function in granule ion homeostasis near the plasma membrane or possibly in other intracellular processes.
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Affiliation(s)
- Gaya P. Yadav
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
| | - Haiyuan Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Joke Ouwendijk
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Stephen Cross
- Wolfson Bioimaging facility, University of Bristol, Bristol, United Kingdom
| | - Qiaochu Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Feng Qin
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Michael X. Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Qiu-Xing Jiang
- Departments of Microbiology and Cell Science and of Medicinal Chemistry, University of Florida, Gainesville, FL, United States
- Departments of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, United States
- Laboratory of Molecular Physiology and Biophysics, Hauptman-Woodward Medical Research Institute, Buffalo, NY, United States
- Cryo-EM Center, Laoshan Laboratory, Qingdao, Shandong, China
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5
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Das BK, Khan WA, Sreekumar SN, Ponraj K, Achary VMM, Reddy ES, Balasubramaniam D, Chandele A, Reddy MK, Arockiasamy A. Plant dehydroascorbate reductase moonlights as membrane integrated ion channel. Arch Biochem Biophys 2023; 741:109603. [PMID: 37084805 DOI: 10.1016/j.abb.2023.109603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 04/03/2023] [Accepted: 04/17/2023] [Indexed: 04/23/2023]
Abstract
Plant dehydroascorbate reductases (DHARs) are only known as soluble antioxidant enzymes of the ascorbate-glutathione pathway. They recycle ascorbate from dehydroascorbate, thereby protecting plants from oxidative stress and the resulting cellular damage. DHARs share structural GST fold with human chloride intracellular channels (HsCLICs) which are dimorphic proteins that exists in soluble enzymatic and membrane integrated ion channel forms. While the soluble form of DHAR has been extensively studied, the existence of a membrane integrated form remains unknown. We demonstrate for the first time using biochemistry, immunofluorescence confocal microscopy, and bilayer electrophysiology that Pennisetum glaucum DHAR (PgDHAR) is dimorphic and is localized to the plant plasma membrane. In addition, membrane translocation increases under induced oxidative stress. Similarly, HsCLIC1 translocates more into peripheral blood mononuclear cells (PBMCs) plasma membrane under induced oxidative stress conditions. Moreover, purified soluble PgDHAR spontaneously inserts and conducts ions in reconstituted lipid bilayers, and the addition of detergent facilitates insertion. In addition to the well-known soluble enzymatic form, our data provides conclusive evidence that plant DHAR also exists in a novel membrane-integrated form. Thus, the structure of DHAR ion channel form will help gain deeper insights into its function across various life forms.
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Affiliation(s)
- Bhaba Krishna Das
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Wajahat Ali Khan
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Sreeshma Nellootil Sreekumar
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India; Department of Biotechnology, Jamia Hamdard University, New Delhi, 110062, India
| | - Kannapiran Ponraj
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - V Mohan Murali Achary
- Crop Improvement Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Elluri Seetharami Reddy
- ICGEB-Emory Vaccine Centre, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India; Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - D Balasubramaniam
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Anmol Chandele
- ICGEB-Emory Vaccine Centre, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Malireddy K Reddy
- Crop Improvement Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Arulandu Arockiasamy
- Membrane Protein Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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6
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Hossain KR, Turkewitz DR, Holt SA, Le Brun AP, Valenzuela SM. Sterol Structural Features' Impact on the Spontaneous Membrane Insertion of CLIC1 into Artificial Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3286-3300. [PMID: 36821411 DOI: 10.1021/acs.langmuir.2c03129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Background: A membrane protein interaction with lipids shows distinct specificity in terms of the sterol structure. The structure of the sterol's polar headgroup, steroidal rings, and aliphatic side chains have all been shown to influence protein membrane interactions, including the initial binding and subsequent oligomerization to form functional channels. Previous studies have provided some insights into the regulatory role that cholesterol plays in the spontaneous membrane insertion of the chloride intracellular ion channel protein, CLIC1. However, the manner in which cholesterol interacts with CLIC1 is yet largely unknown. Method: In this study, the CLIC1 interaction with different lipid:sterol monolayers was studied using the Langmuir trough and neutron reflectometry in order to investigate the structural features of cholesterol essential for the spontaneous membrane insertion of the CLIC1 protein. Molecular docking simulations were also performed to study the binding affinities between CLIC1 and the different sterol molecules. Results: This study, for the first time, highlights the vital role of the free sterol 3β-OH group as an essential structural requirement for the interaction of CLIC1 with cholesterol. Furthermore, the presence of additional hydroxyl groups, methylation of the sterol skeleton, and the structure of the sterol alkyl side chain have also been shown to modulate the magnitude of CLIC1 interaction with sterols and hence their spontaneous membrane insertion. This study also reports the ability of CLIC1 to interact with other naturally existing sterol molecules. General Significance: Like the sterol molecules, CLIC proteins are evolutionarily conserved with almost all vertebrates expressing six CLIC proteins (CLIC1-6), and CLIC-like proteins are also present in invertebrates and have also been reported in plants. This discovery of CLIC1 protein interaction with other natural sterols and the sterol structural requirements for CLIC membrane insertion provide key information to explore the feasibility of exploiting these properties for therapeutic and prophylactic purposes.
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Affiliation(s)
- Khondker R Hossain
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales 2234, Australia
| | - Daniel R Turkewitz
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Stephen A Holt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales 2234, Australia
| | - Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, New South Wales 2234, Australia
| | - Stella M Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
- Institute for Biomedical Materials and Devices (IBMD), University of Technology Sydney, Sydney, New South Wales 2007, Australia
- ARC Research Hub for Integrated Device for End-User Analysis at Low-Levels (IDEAL Hub), Faculty of Science, University of Technology Sydney, , Sydney, New South Wales 2007, Australia
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7
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Alzaydi MM, Abdul-Salam VB, Whitwell HJ, Russomanno G, Glynos A, Capece D, Szabadkai G, Wilkins MR, Wojciak-Stothard B. Intracellular Chloride Channels Regulate Endothelial Metabolic Reprogramming in Pulmonary Arterial Hypertension. Am J Respir Cell Mol Biol 2023; 68:103-115. [PMID: 36264759 PMCID: PMC9817916 DOI: 10.1165/rcmb.2022-0111oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial fission and a metabolic switch from oxidative phosphorylation to glycolysis are key features of vascular pathology in pulmonary arterial hypertension (PAH) and are associated with exuberant endothelial proliferation and apoptosis. The underlying mechanisms are poorly understood. We describe the contribution of two intracellular chloride channel proteins, CLIC1 and CLIC4, both highly expressed in PAH and cancer, to mitochondrial dysfunction and energy metabolism in PAH endothelium. Pathological overexpression of CLIC proteins induces mitochondrial fragmentation, inhibits mitochondrial cristae formation, and induces metabolic shift toward glycolysis in human pulmonary artery endothelial cells, consistent with changes observed in patient-derived cells. Interactions of CLIC proteins with structural components of the inner mitochondrial membrane offer mechanistic insights. Endothelial CLIC4 excision and mitofusin 2 supplementation have protective effects in human PAH cells and preclinical PAH. This study is the first to demonstrate the key role of endothelial intracellular chloride channels in the regulation of mitochondrial structure, biogenesis, and metabolic reprogramming in expression of the PAH phenotype.
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Affiliation(s)
- Mai M. Alzaydi
- National Heart and Lung Institute,,National Center for Biotechnology, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
| | - Vahitha B. Abdul-Salam
- National Heart and Lung Institute,,Centre for Cardiovascular Medicine and Device Innovation, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Harry J. Whitwell
- National Phenome Centre and Imperial Clinical Phenotyping Centre, and,Section of Bioanalytical Chemistry, Division of Systems Medicine, Department of Metabolism, Digestion, and Reproduction, and
| | - Giusy Russomanno
- National Heart and Lung Institute,,Medical Research Council (MRC) Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, Institute of Systems, Molecular, and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Angelos Glynos
- Mitochondrial Biology Unit, Medical Research Council, University of Cambridge, Cambridge, United Kingdom; and
| | - Daria Capece
- Centre for Cell Signalling and Inflammation, Department of Immunology and Inflammation, Imperial College London, London, United Kingdom
| | - Gyorgy Szabadkai
- Cell and Developmental Biology, University College London, London, United Kingdom
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8
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Varela L, Hendry AC, Cassar J, Martin-Escolano R, Cantoni D, Ossa F, Edwards JC, Abdul-Salam V, Ortega-Roldan JL. Zn2+ triggered two-step mechanism of CLIC1 membrane insertion and activation into chloride channels. J Cell Sci 2022; 135:276009. [PMID: 35833483 PMCID: PMC9511705 DOI: 10.1242/jcs.259704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 07/04/2022] [Indexed: 11/21/2022] Open
Abstract
The chloride intracellular channel (CLIC) protein family displays the unique feature of altering its structure from a soluble form to a membrane-bound chloride channel. CLIC1, a member of this family, is found in the cytoplasm or in internal and plasma membranes, with membrane relocalisation linked to endothelial disfunction, tumour proliferation and metastasis. The molecular switch promoting CLIC1 activation remains under investigation. Here, cellular Cl− efflux assays and immunofluorescence microscopy studies have identified intracellular Zn2+ release as the trigger for CLIC1 activation and membrane insertion. Biophysical assays confirmed specific binding to Zn2+, inducing membrane association and enhancing Cl− efflux in a pH-dependent manner. Together, our results identify a two-step mechanism with Zn2+ binding as the molecular switch promoting CLIC1 membrane insertion, followed by pH-mediated activation of Cl− efflux. Summary: Identification of a two-step mechanism of CLIC1 membrane insertion based on Zn2+ binding and pH activation of Cl− efflux.
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Affiliation(s)
- Lorena Varela
- School of Biosciences. University of Kent. CT2 7NJ. Canterbury, UK
| | - Alex C Hendry
- School of Biosciences. University of Kent. CT2 7NJ. Canterbury, UK
| | - Joseph Cassar
- School of Biosciences. University of Kent. CT2 7NJ. Canterbury, UK
| | | | - Diego Cantoni
- Medway School of Pharmacy, The Universities of Kent and Greenwich at Medway, Chatham, ME7 4TB, UK
| | - Felipe Ossa
- Centre for Cardiovascular Medicine and Device Innovation, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - John C Edwards
- Department of Internal Medicine, Saint Louis University, St. Louis, MO, USA
| | - Vahitha Abdul-Salam
- Centre for Cardiovascular Medicine and Device Innovation, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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9
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Wang H, An J, He S, Liao C, Wang J, Tuo B. Chloride intracellular channels as novel biomarkers for digestive system tumors (Review). Mol Med Rep 2021; 24:630. [PMID: 34278487 DOI: 10.3892/mmr.2021.12269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 05/19/2021] [Indexed: 11/06/2022] Open
Abstract
Digestive system malignant tumors are common tumors, and the traditional treatment methods for these tumors include surgical resection, radiotherapy, chemotherapy, and molecularly targeted drugs. However, diagnosis remains challenging, and the early detection of postoperative recurrence is complicated. Therefore, it is necessary to explore novel biomarkers to facilitate clinical diagnosis and treatment. Accumulating evidence supports the crucial role of chloride channels in the development of multiple types of cancers. Given that chloride channels are widely expressed and involved in cell proliferation, apoptosis and cell cycle, among other processes, they may serve as a promising diagnostic and therapeutic target. Chloride intracellular channels (CLICs) are a class of chloride channels that are upregulated or downregulated in certain types of cancer. Furthermore, in certain cases, during cell cycle progression, the localization and function of the cytosolic form of the transmembrane proteins of CLICs are also altered, which may provide a key target for cancer therapy. The aim of the present review was to focus on CLICs as biomarkers for digestive system tumors.
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Affiliation(s)
- Hui Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jiaxing An
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Suyu He
- The Fourth Department of the Digestive Disease Center, Suining Central Hospital, Suining, Sichuan 629000, P.R. China
| | - Chengcheng Liao
- Special Key Laboratory of Oral Disease Research, Higher Education Institution in Guizhou Province, School of Stomatology, Zunyi Medical University, Zunyi, Guizhou 563006, P.R. China
| | - Juan Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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10
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Weston RM, Schmitt RE, Grotewiel M, Miles MF. Transcriptome analysis of chloride intracellular channel knockdown in Drosophila identifies oxidation-reduction function as possible mechanism of altered sensitivity to ethanol sedation. PLoS One 2021; 16:e0246224. [PMID: 34228751 PMCID: PMC8259981 DOI: 10.1371/journal.pone.0246224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/18/2021] [Indexed: 01/22/2023] Open
Abstract
Chloride intracellular channels (CLICs) are a unique family of evolutionarily conserved metamorphic proteins, switching between stable conformations based on redox conditions. CLICs have been implicated in a wide variety biological processes including ion channel activity, apoptosis, membrane trafficking, and enzymatic oxidoreductase activity. Understanding the molecular mechanisms by which CLICs engage in these activities is an area of active research. Here, the sole Drosophila melanogaster ortholog, Clic, was targeted for RNAi knockdown to identify genes and biological processes associated with Clic expression. Clic knockdown had a substantial impact on global transcription, altering expression of over 7% of transcribed Drosophila genes. Overrepresentation analysis of differentially expressed genes identified enrichment of Gene Ontology terms including Cytoplasmic Translation, Oxidation-Reduction Process, Heme Binding, Membrane, Cell Junction, and Nucleolus. The top term, Cytoplasmic Translation, was enriched almost exclusively with downregulated genes. Drosophila Clic and vertebrate ortholog Clic4 have previously been tied to ethanol sensitivity and ethanol-regulated expression. Clic knockdown-responsive genes from the present study were found to overlap significantly with gene sets from 4 independently published studies related to ethanol exposure and sensitivity in Drosophila. Bioinformatic analysis of genes shared between these studies revealed an enrichment of genes related to amino acid metabolism, protein processing, oxidation-reduction processes, and lipid particles among others. To determine whether the modulation of ethanol sensitivity by Clic may be related to co-regulated oxidation-reduction processes, we evaluated the effect of hyperoxia on ethanol sedation in Clic knockdown flies. Consistent with previous findings, Clic knockdown reduced acute ethanol sedation sensitivity in flies housed under normoxia. However, this effect was reversed by exposure to hyperoxia, suggesting a common set of molecular-genetic mechanism may modulate each of these processes. This study suggests that Drosophila Clic has a major influence on regulation of oxidative stress signaling and that this function overlaps with the molecular mechanisms of acute ethanol sensitivity in the fly.
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Affiliation(s)
- Rory M. Weston
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Rebecca E. Schmitt
- VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Mike Grotewiel
- VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Michael F. Miles
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, United States of America
- VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, Virginia, United States of America
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11
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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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12
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Pooe K, Worth R, Iwuchukwu EA, Dirr HW, Achilonu I. An empirical and theoretical description of Schistosoma japonicum glutathione transferase inhibition by bromosulfophthalein and indanyloxyacetic acid 94. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.128892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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13
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Medina-Carmona E, Varela L, Hendry AC, Thompson GS, White LJ, Boles JE, Hiscock JR, Ortega-Roldan JL. A quantitative assay to study the lipid selectivity of membrane-associated systems using solution NMR. Chem Commun (Camb) 2020; 56:11665-11668. [PMID: 33000772 DOI: 10.1039/d0cc03612a] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
The activity of membrane proteins and compounds that interact with the membrane is modulated by the surrounding lipid composition. However, there are no simple methods that determine the composition of these annular phospholipids in eukaryotic systems. Herein, we describe a simple methodology that enables the identification and quantification of the lipid composition around membrane-associated compounds using SMA-nanodiscs and routine 1H-31P NMR.
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14
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Zhao N, Li CC, Di B, Xu LL. Recent advances in the NEK7-licensed NLRP3 inflammasome activation: Mechanisms, role in diseases and related inhibitors. J Autoimmun 2020; 113:102515. [PMID: 32703754 DOI: 10.1016/j.jaut.2020.102515] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022]
Abstract
The nucleotide-binding oligomerization domain (NOD)-like receptor containing pyrin domain 3 (NLRP3) inflammasome is a high-molecular-weight complex mediated by the activation of pattern-recognition receptors (PRRs) seed in innate immunity. Once NLRP3 is activated, the following recruitment of the adapter apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD) (ASC) and procaspase-1 would be initiated. Cleavage of procaspase-1 into active caspase-1 then leads to the maturation of the precursor forms of interleukin (IL)-1β and IL-18 into biologically active IL-1β and IL-18. The activation of NLRP3 inflammasome is thought to be tightly associated with a regulator never in mitosis A (NIMA)-related kinase 7 (NEK7), apart from other signaling events such as K+ efflux and reactive oxygen species (ROS). Plus, the NLRP3 inflammasome has been linked to various metabolic disorders, chronic inflammation and other diseases. In this review, we firstly describe the cellular/molecular mechanisms of the NEK7-licensed NLRP3 inflammasome activation. Then we detail the potential inhibitors that can selectively and effectively modulate either the NEK7-NLRP3 complex itself or the related molecular/cellular events. Finally, we describe some inhibitors as promising therapeutic strategies for diverse diseases driven by NLRP3 inflammasome.
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Affiliation(s)
- Ni Zhao
- Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Cui-Cui Li
- Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China
| | - Bin Di
- Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China.
| | - Li-Li Xu
- Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing, 210009, China.
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15
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Zhang Y, Bracken H, Woolhead C, Zagnoni M. Functionalisation of human chloride intracellular ion channels in microfluidic droplet-interface-bilayers. Biosens Bioelectron 2019; 150:111920. [PMID: 31791876 DOI: 10.1016/j.bios.2019.111920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/12/2019] [Accepted: 11/23/2019] [Indexed: 01/06/2023]
Abstract
Profiling ion flux through human intracellular chloride ion channels using live-cell based techniques, such as patch-clamp electrophysiology, is laborious and time-consuming. The integration of scalable microfluidic systems with automatable protocols based on droplet-interface-bilayers (DIBs) within which ion channels are incorporated circumvents several limitations associated with live-cell measurements and facilitates testing in controllable in vitro conditions. Here, we have designed and tested novel microfluidic layouts for the formation of arrays of DIBs in parallel and developed the first example of a miniaturised, DIB-based, fluorescence assays for Cl- fluxing, allowing the investigation of the functional properties of the human chloride intracellular ion channel 1 (CLIC1). The microfluidic protocols relied on passive geometries for droplet pairing and DIB formation. Using recombinantly expressed CLIC1, we identified the best conditions to maximise protein integration into a lipid bilayer and the oligomerisation of the protein into functional ion channels. Finally, CLIC1 ion channel functionality was assessed relative to α-Haemolysin into microfluidic DIBs using the same Cl- fluxing assay.
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Affiliation(s)
- Yu Zhang
- Centre for Microsystems and Photonics, EEE Dept., University of Strathclyde, Glasgow, UK
| | - Hazel Bracken
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Cheryl Woolhead
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Michele Zagnoni
- Centre for Microsystems and Photonics, EEE Dept., University of Strathclyde, Glasgow, UK.
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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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Mishra S, Looger LL, Porter LL. Inaccurate secondary structure predictions often indicate protein fold switching. Protein Sci 2019; 28:1487-1493. [PMID: 31148305 PMCID: PMC6635839 DOI: 10.1002/pro.3664] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/22/2019] [Indexed: 01/08/2023]
Abstract
Although most proteins conform to the classical one‐structure/one‐function paradigm, an increasing number of proteins with dual structures and functions have been discovered. In response to cellular stimuli, such proteins undergo structural changes sufficiently dramatic to remodel even their secondary structures and domain organization. This “fold‐switching” capability fosters protein multi‐functionality, enabling cells to establish tight control over various biochemical processes. Accurate predictions of fold‐switching proteins could both suggest underlying mechanisms for uncharacterized biological processes and reveal potential drug targets. Recently, we developed a prediction method for fold‐switching proteins using structure‐based thermodynamic calculations and discrepancies between predicted and experimentally determined protein secondary structure (Porter and Looger, Proc Natl Acad Sci U S A 2018; 115:5968–5973). Here we seek to leverage the negative information found in these secondary structure prediction discrepancies. To do this, we quantified secondary structure prediction accuracies of 192 known fold‐switching regions (FSRs) within solved protein structures found in the Protein Data Bank (PDB). We find that the secondary structure prediction accuracies for these FSRs vary widely. Inaccurate secondary structure predictions are strongly associated with fold‐switching proteins compared to equally long segments of non‐fold‐switching proteins selected at random. These inaccurate predictions are enriched in helix‐to‐strand and strand‐to‐coil discrepancies. Finally, we find that most proteins with inaccurate secondary structure predictions are underrepresented in the PDB compared with their alternatively folded cognates, suggesting that unequal representation of fold‐switching conformers within the PDB could be an important cause of inaccurate secondary structure predictions. These results demonstrate that inconsistent secondary structure predictions can serve as a useful preliminary marker of fold switching.
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Affiliation(s)
- Soumya Mishra
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia, 20147
| | - Loren L Looger
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia, 20147
| | - Lauren L Porter
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia, 20147
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18
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Hossain KR, Turkewitz DR, Holt SA, Herson L, Brown LJ, Cornell BA, Curmi PMG, Valenzuela SM. A conserved GXXXG motif in the transmembrane domain of CLIC proteins is essential for their cholesterol-dependant membrane interaction. Biochim Biophys Acta Gen Subj 2019; 1863:1243-1253. [PMID: 31075359 DOI: 10.1016/j.bbagen.2019.04.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/25/2019] [Accepted: 04/29/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Sterols have been reported to modulate conformation and hence the function of several membrane proteins. One such group is the Chloride Intracellular Ion Channel (CLIC) family of proteins. The CLIC protein family consists of six evolutionarily conserved protein members in vertebrates. These proteins exist as both monomeric soluble proteins and as membrane bound proteins. To date, the structure of their membrane-bound form remains unknown. In addition to several studies indicating cellular redox environment and pH as facilitators of CLIC1 insertion into membranes, we have also demonstrated that the spontaneous membrane insertion of CLIC1 is regulated by membrane cholesterol. METHOD We have performed Langmuir-film, Impedance Spectroscopy and Molecular Docking Simulations to study the role of this GXXXG motif in CLIC1 interaction with cholesterol. RESULTS Unlike CLIC1-wild-type protein, the G18A and G22A mutants, that form part of the GXXXG motif, showed much slower initial kinetics and lower ion channel activity compared to the native protein. This difference can be attributed to the significantly reduced membrane interaction and insertion rate of the mutant proteins and/or slower formation of the final membrane configuration of the mutant proteins once in the membrane. CONCLUSION In this study, our findings uncover the identification of a GXXXG motif in CLIC1, which likely serves as the cholesterol-binding domain, that facilitates the protein's membrane interaction and insertion. Furthermore, we were able to postulate a model by which CLIC1 can autonomously insert into membranes to form functional ion channels. GENERAL SIGNIFICANCE Members of the CLIC family of proteins demonstrate unusual structural and dual functional properties - as ion channels and enzymes. Elucidating how the CLIC proteins' interact with membranes, thus allowing them to switch between their soluble and membrane form, will provide key information as to a mechanism of moonlighting activity and a novel regulatory role for cholesterol in such a process.
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Affiliation(s)
- Khondker Rufaka Hossain
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Daniel R Turkewitz
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Stephen A Holt
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Height, Australian Centre for Neutron Scattering, New South Wales 2234, Australia
| | - Leonie Herson
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, New South Wales 2109, Australia
| | - Bruce A Cornell
- Surgical Diagnostics Pty Ltd., Roseville, Sydney 2069, Australia; Institute for Biomedical Materials and Devices, University of Technology Sydney, Sydney, New South Wales 2007, Australia
| | - Paul M G Curmi
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Stella M Valenzuela
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales 2007, Australia; Institute for Biomedical Materials and Devices, University of Technology Sydney, Sydney, New South Wales 2007, Australia.
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19
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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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20
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Tang T, Lang X, Xu C, Wang X, Gong T, Yang Y, Cui J, Bai L, Wang J, Jiang W, Zhou R. CLICs-dependent chloride efflux is an essential and proximal upstream event for NLRP3 inflammasome activation. Nat Commun 2017; 8:202. [PMID: 28779175 PMCID: PMC5544706 DOI: 10.1038/s41467-017-00227-x] [Citation(s) in RCA: 232] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 06/11/2017] [Indexed: 12/30/2022] Open
Abstract
The NLRP3 inflammasome can sense different pathogens or danger signals, and has been reported to be involved in the development of many human diseases. Potassium efflux and mitochondrial damage are both reported to mediate NLRP3 inflammasome activation, but the underlying, orchestrating signaling events are still unclear. Here we show that chloride intracellular channels (CLIC) act downstream of the potassium efflux-mitochondrial reactive oxygen species (ROS) axis to promote NLRP3 inflammasome activation. NLRP3 agonists induce potassium efflux, which causes mitochondrial damage and ROS production. Mitochondrial ROS then induces the translocation of CLICs to the plasma membrane for the induction of chloride efflux to promote NEK7-NLRP3 interaction, inflammasome assembly, caspase-1 activation, and IL-1β secretion. Thus, our results identify CLICs-dependent chloride efflux as an essential and proximal upstream event for NLRP3 activation.The NLRP3 inflammasome is key to the regulation of innate immunity against pathogens or stress, but the underlying signaling regulation is still unclear. Here the authors show that chloride intracellular channels (CLIC) interface between mitochondria stress and inflammasome activation to modulate inflammatory responses.
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Affiliation(s)
- Tiantian Tang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China.,Innovation Center for Cell Signalling Network, University of Science and Technology of China, Hefei, 230027, China.,Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230027, China
| | - Xueting Lang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Congfei Xu
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Xiaqiong Wang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Tao Gong
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Yanqing Yang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Jun Cui
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510080, China
| | - Li Bai
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Jun Wang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China
| | - Wei Jiang
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China. .,Innovation Center for Cell Signalling Network, University of Science and Technology of China, Hefei, 230027, China.
| | - Rongbin Zhou
- Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease, CAS center for Excellence in Molecular Cell Sciences, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, 230027, China. .,Innovation Center for Cell Signalling Network, University of Science and Technology of China, Hefei, 230027, China. .,Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, 230027, China.
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21
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Tomasek M, Misak A, Grman M, Tomaskova Z. Subconductance states of mitochondrial chloride channels: implication for functionally-coupled tetramers. FEBS Lett 2017. [PMID: 28640976 DOI: 10.1002/1873-3468.12721] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Recently, it has been discovered that isoforms of intracellular chloride channels (CLIC) are present in cardiac mitochondria. By reconstituting rat cardiac mitochondrial chloride channels into bilayer lipid membranes, we detected three equally separated subconductance states with conductance increment of 45 pS and < 2% occupancy. The observed rare events of channel decomposition into substates, accompanied by disrupted gating, provide an insight into channel quaternary structure. Our findings suggest that the observed channels work as four functionally coupled subunits with synchronized gating. We discuss the putative connection of channel activity from native mitochondria with the recombinant CLIC channels. However, conclusive evidence is needed to prove this connection.
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Affiliation(s)
| | - Anton Misak
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak
| | - Marian Grman
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak
| | - Zuzana Tomaskova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovak
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22
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Tavasoli M, Al-Momany A, Wang X, Li L, Edwards JC, Ballermann BJ. Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium. Am J Physiol Renal Physiol 2016; 311:F945-F957. [PMID: 27582103 DOI: 10.1152/ajprenal.00353.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 08/25/2016] [Indexed: 01/17/2023] Open
Abstract
The chloride intracellular channel (CLIC) 5A is expressed at very high levels in renal glomeruli, in both endothelial cells (EC) and podocytes. CLIC5A stimulates Rac1- and phosphatidylinositol (4,5)-bisphosphate-dependent ERM (ezrin, radixin, moesin) activation. ERM proteins, in turn, function in lumen formation and in the development of actin-based cellular projections. In mice lacking CLIC5A, ERM phosphorylation is profoundly reduced in podocytes, but preserved in glomerular EC. Since glomerular EC also express CLIC4, we reasoned that, if CLIC4 activates ERM proteins like CLIC5A, then CLIC4 could compensate for the CLIC5A loss in glomerular EC. In glomeruli of CLIC5-deficient mice, CLIC4 expression was upregulated and colocalized with moesin and ezrin in glomerular EC, but not in podocytes. In cultured glomerular EC, CLIC4 silencing reduced ERM phosphorylation and cytoskeletal association, and expression of exogenous CLIC4 or CLIC5A rescued ERM de-phosphorylation due to CLIC4 silencing. In mice lacking either CLIC4 or CLIC5, ERM phosphorylation was retained in glomerular EC, but, in mice lacking both CLIC4 and CLIC5, glomerular EC ERM phosphorylation was profoundly reduced. Although glomerular EC fenestrae developed normally in dual CLIC4/CLIC5-deficient mice, the density of fenestrae declined substantially by 8 mo of age, along with the deposition of subendothelial electron-lucent material. The dual CLIC4/CLIC5-deficient mice developed spontaneous proteinuria, glomerular cell proliferation, and matrix deposition. Thus CLIC4 stimulates ERM activation and can compensate for CLIC5A in glomerular EC. The findings indicate that CLIC4/CLIC5A-mediated ERM activation is required for maintenance of the glomerular capillary architecture.
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Affiliation(s)
- Mahtab Tavasoli
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Abass Al-Momany
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
| | - Xin Wang
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Laiji Li
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - John C Edwards
- Department of Internal Medicine, St. Louis University, St. Louis, Missouri
| | - Barbara J Ballermann
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; .,Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; and
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Abstract
Hepatocytes express an array of plasma membrane and intracellular ion channels, yet their role during the hepatitis C virus (HCV) life cycle remains largely undefined. Here, we show that HCV increases intracellular hepatic chloride (Cl(-)) influx that can be inhibited by selective Cl(-) channel blockers. Through pharmacological and small interfering RNA (siRNA)-mediated silencing, we demonstrate that Cl(-) channel inhibition is detrimental to HCV replication. This represents the first observation of the involvement of Cl(-) channels during the HCV life cycle.
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Al-Momany A, Li L, Alexander RT, Ballermann BJ. Clustered PI(4,5)P₂ accumulation and ezrin phosphorylation in response to CLIC5A. J Cell Sci 2014; 127:5164-78. [PMID: 25344252 DOI: 10.1242/jcs.147744] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
CLIC5A (encoded by CLIC5) is a component of the ezrin-NHERF2-podocalyxin complex in renal glomerular podocyte foot processes. We explored the mechanism(s) by which CLIC5A regulates ezrin function. In COS-7 cells, CLIC5A augmented ezrin phosphorylation without changing ezrin abundance, increased the association of ezrin with the cytoskeletal fraction and enhanced actin polymerization and the formation of cell surface projections. CLIC5A caused the phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] reporter RFP-PH-PLC to translocate from the cytosol to discrete plasma membrane clusters at the cell surface, where it colocalized with CLIC5A. Transiently expressed HA-PIP5Kα colocalized with GFP-CLIC5A and was pulled from cell lysates by GST-CLIC5A, and silencing of endogenous PIP5Kα abrogated CLIC5A-dependent ERM phosphorylation. N- and C-terminal deletion mutants of CLIC5A, which failed to associate with the plasma membrane, failed to colocalize with PIP5Kα, did not alter the abundance of PI(4,5)P2 plasma membrane clusters and failed to enhance ezrin phosphorylation. Relative to wild-type mice, in CLIC5-deficient mice, the phosphorylation of glomerular ezrin was diminished and the cytoskeletal association of both ezrin and NHERF2 was reduced. Therefore, the mechanism of CLIC5A action involves clustered plasma membrane PI(4,5)P2 accumulation through an interaction of CLIC5A with PI(4,5)P2-generating kinases, in turn facilitating ezrin activation and actin-dependent cell surface remodeling.
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Affiliation(s)
- Abass Al-Momany
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Laiji Li
- Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - R Todd Alexander
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AL T6G 2V2, Canada
| | - Barbara J Ballermann
- Department of Physiology, University of Alberta, Edmonton, AL T6G 2V2, Canada Department of Medicine (Nephrology), University of Alberta, Edmonton, AL T6G 2V2, Canada
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25
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Cross M, Fernandes M, Dirr H, Fanucchi S. Glutamate 85 and glutamate 228 contribute to the pH-response of the soluble form of chloride intracellular channel 1. Mol Cell Biochem 2014; 398:83-93. [PMID: 25209805 DOI: 10.1007/s11010-014-2207-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/30/2014] [Indexed: 10/24/2022]
Abstract
The chloride intracellular channel protein, CLIC1, is synthesised as a soluble monomer that can reversibly bind membranes. Soluble CLIC1 is proposed to respond to the low pH found at a membrane surface by partially unfolding and restructuring into a membrane-competent conformation. This transition is proposed to be controlled by strategically located "pH-sensor" residues that become protonated at acidic pH. In this study, we investigate the role of two conserved glutamate residues, Glu85 in the N-domain and Glu228 in the C-domain, as pH-sensors. E85L and E228L CLIC1 variants were created to reduce pH sensitivity by permanently breaking the bonds these residues form. The structure and stability of each variant was compared to the wild type at both pH 7.0 and pH 5.5. Neither substitution significantly altered the structure but both decreased the conformational stability. Furthermore, E85L CLIC1 formed a urea-induced unfolding intermediate state at both pH 7 and pH 5.5 compared to wild-type and E228L CLIC1 which only formed the intermediate at pH 5.5. We conclude that Glu85 and Glu228 are two of the five pH-sensor residues of CLIC1 and contribute to the pH-response in different ways. Glu228 lowers the stability of the native state at pH 5.5, while Glu85 contributes both to the stability of the native state and to the formation of the intermediate state. By putting these interactions into the context of the three previously described CLIC1 pH-sensor residues, we propose a mechanism for the conversion of CLIC1 from the soluble state to the pre-membrane form.
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Affiliation(s)
- Megan Cross
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, 1 Jan Smuts Ave, Johannesburg, 2050, South Africa
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26
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Misak A, Grman M, Malekova L, Novotova M, Markova J, Krizanova O, Ondrias K, Tomaskova Z. Mitochondrial chloride channels: electrophysiological characterization and pH induction of channel pore dilation. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2013; 42:709-20. [PMID: 23903554 DOI: 10.1007/s00249-013-0920-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/08/2013] [Accepted: 07/13/2013] [Indexed: 11/26/2022]
Abstract
Physiological and pathological functions of mitochondria are highly dependent on the properties and regulation of mitochondrial ion channels. There is still no clear understanding of the molecular identity, regulation, and properties of anion mitochondrial channels. The inner membrane anion channel (IMAC) was assumed to be equivalent to mitochondrial centum picosiemens (mCS). However, the different properties of IMAC and mCS channels challenges this opinion. In our study, we characterized the single-channel anion selectivity and pH regulation of chloride channels from purified cardiac mitochondria. We observed that channel conductance decreased in the order: Cl⁻ > Br⁻ > I⁻ > chlorate ≈ formate > acetate, and that gluconate did not permeate under control conditions. The selectivity sequence was Br⁻ ≥ chlorate ≥ I⁻ ≥ Cl⁻ ≥ formate ≈ acetate. Measurement of the concentration dependence of chloride conductance revealed altered channel gating kinetics, which was demonstrated by prolonged mean open time value with increasing chloride concentration. The observed mitochondrial chloride channels were in many respects similar to those of mCS, but not those of IMAC. Surprisingly, we observed that acidic pH increased channel conductance and that an increase of pH from 7.4 to 8.5 reduced it. The gluconate current appeared and gradually increased when pH decreased from pH 7.0 to 5.6. Our results indicate that pH regulates the channel pore diameter in such a way that dilation increases with more acidic pH. We assume this newly observed pH-dependent anion channel property may be involved in pH regulation of anion distribution in different mitochondrial compartments.
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Affiliation(s)
- Anton Misak
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlarska 5, 83334 Bratislava, Slovak Republic
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27
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Intracellular ion channel CLIC1: involvement in microglia-mediated β-amyloid peptide(1-42) neurotoxicity. Neurochem Res 2013; 38:1801-8. [PMID: 23743620 DOI: 10.1007/s11064-013-1084-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/10/2013] [Accepted: 05/23/2013] [Indexed: 10/26/2022]
Abstract
Microglia can exacerbate central nervous system disorders, including stroke and chronic progressive neurodegenerative diseases such as Alzheimer disease. Mounting evidence points to ion channels expressed by microglia as contributing to these neuropathologies. The Chloride Intracellular Channel (CLIC) family represents a class of chloride intracellular channel proteins, most of which are localized to intracellular membranes. CLICs are unusual in that they possess both soluble and integral membrane forms. Amyloid β-peptide (Aβ) accumulation in plaques is a hallmark of familial Alzheimer disease. The truncated Aβ25-35 species was shown previously to increase the expression of CLIC1 chloride conductance in cortical microglia and to provoke microglial neurotoxicity. However, the highly pathogenic and fibrillogenic full-length Aβ1-42 species was not examined, nor was the potential role of CLIC1 in mediating microglial activation and neurotoxicity by other stimuli (e.g. ligands for the Toll-like receptors). In the present study, we utilized a two chamber Transwell™ cell culture system to allow separate treatment of microglia and neurons while examining the effect of pharmacological blockade of CLIC1 in protecting cortical neurons from toxicity caused by Aβ1-42- and lipopolysaccaride-stimulated microglia. Presentation of Aβ1-42 to the upper, microglia-containing chamber resulted in a progressive loss of neurons over 3 days. Neuronal cell injury was prevented by the CLIC1 ion channel blockers IAA-94 [(R(+)-[(6,7-dichloro-2-cyclopentyl-2,3-dihydro-2-methyl-1-oxo-1H-inden-5yl)-oxy] acetic acid)] and niflumic acid (2-{[3-(trifluoromethyl)phenyl]amino}nicotinic acid) when presented to the upper chamber only. Incubation of microglia with lipopolysaccharide plus interferon-γ led to neuronal cell injury which, however, was insensitive to inhibition by the CLIC1 channel blockers, suggesting a degree of selectivity in agents leading to CLIC1 activation.
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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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Costa JA, Nguyen DA, Leal-Pinto E, Gordon RE, Hanss B. Wicking: a rapid method for manually inserting ion channels into planar lipid bilayers. PLoS One 2013; 8:e60836. [PMID: 23717384 PMCID: PMC3662662 DOI: 10.1371/journal.pone.0060836] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/03/2013] [Indexed: 11/18/2022] Open
Abstract
The planar lipid bilayer technique has a distinguished history in electrophysiology but is arguably the most technically difficult and time-consuming method in the field. Behind this is a lack of experimental consistency between laboratories, the challenges associated with painting unilamellar bilayers, and the reconstitution of ion channels into them. While there has be a trend towards automation of this technique, there remain many instances where manual bilayer formation and subsequent membrane protein insertion is both required and advantageous. We have developed a comprehensive method, which we have termed “wicking”, that greatly simplifies many experimental aspects of the lipid bilayer system. Wicking allows one to manually insert ion channels into planar lipid bilayers in a matter of seconds, without the use of a magnetic stir bar or the addition of other chemicals to monitor or promote the fusion of proteoliposomes. We used the wicking method in conjunction with a standard membrane capacitance test and a simple method of proteoliposome preparation that generates a heterogeneous mixture of vesicle sizes. To determine the robustness of this technique, we selected two ion channels that have been well characterized in the literature: CLIC1 and α-hemolysin. When reconstituted using the wicking technique, CLIC1 showed biophysical characteristics congruent with published reports from other groups; and α-hemolysin demonstrated Type A and B events when threading single stranded DNA through the pore. We conclude that the wicking method gives the investigator a high degree of control over many aspects of the lipid bilayer system, while greatly reducing the time required for channel reconstitution.
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Affiliation(s)
- Justin A. Costa
- Division of Nephrology, Department of Medicine and Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Department of Systems Biology of Disease and Therapeutics, Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Dac A. Nguyen
- Division of Nephrology, Department of Medicine and Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- NIH Medical Scientist Training Program, The Mount Sinai School of Medicine, New York, New York, United States of America
- Department of Systems Biology of Disease and Therapeutics, Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Edgar Leal-Pinto
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Ronald E. Gordon
- Department of Pathology, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Basil Hanss
- Division of Nephrology, Department of Medicine and Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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30
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Kim KH, Choi BK, Song KM, Cha KW, Kim YH, Lee H, Han IS, Kwon BS. CRIg signals induce anti-intracellular bacterial phagosome activity in a chloride intracellular channel 3-dependent manner. Eur J Immunol 2013; 43:667-78. [PMID: 23280470 DOI: 10.1002/eji.201242997] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/14/2012] [Accepted: 12/20/2012] [Indexed: 11/10/2022]
Abstract
Macrophages provide a first line of defense against bacterial infection by engulfing and killing invading bacteria, but intracellular bacteria such as Listeria monocytogenes (LM) can survive in macrophages by various mechanisms of evasion. Complement receptor of the immunoglobulin (CRIg), a C3b receptor, binds to C3b on opsonized bacteria and facilitates clearance of the bacteria by promoting their uptake. We found that CRIg signaling induced by agonistic anti-CRIg mAb enhanced the killing of intracellular LM by macrophages, and that this occurred in LM-containing phagosomes. Chloride intra-cellular channel 3 CLIC3, an intracellular chloride channel protein, was essential for CRIg-mediated LM killing by directly interacting with the cytoplasmic domain of CRIg, and the two proteins colocalized on the membranes of LM-containing vacuoles. CLIC3(-/-) mice were as susceptible to LM as CRIg(-/-) mice. These findings identify a mechanism embedded in the process by which macrophages take up opsonized bacteria that prevents the bacteria from evading cell-mediated killing.
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Affiliation(s)
- Kwang H Kim
- Cancer Immunology Branch, Division of Cancer Biology, National Cancer Center, Goyang, Korea
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31
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Achilonu I, Fanucchi S, Cross M, Fernandes M, Dirr HW. Role of individual histidines in the pH-dependent global stability of human chloride intracellular channel 1. Biochemistry 2012; 51:995-1004. [PMID: 22242893 DOI: 10.1021/bi201541w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chloride intracellular channel proteins exist in both a soluble cytosolic form and a membrane-bound form. The mechanism of conversion between the two forms is not properly understood, although one of the contributing factors is believed to be the variation in pH between the cytosol (~7.4) and the membrane (~5.5). We systematically mutated each of the three histidine residues in CLIC1 to an alanine at position 74 and a phenylalanine at positions 185 and 207. We examined the effect of the histidine-mediated pH dependence on the structure and global stability of CLIC1. None of the mutations were found to alter the global structure of the protein. However, the stability of H74A-CLIC1 and H185F-CLIC1, as calculated from the equilibrium unfolding data, is no longer dependent on pH because similar trends are observed at pH 7.0 and 5.5. The crystal structures show that the mutations result in changes in the local hydrogen bond coordination. Because the mutant total free energy change upon unfolding is not different from that of the wild type at pH 7.0, despite the presence of intermediates that are not seen in the wild type, we propose that it may be the stability of the intermediate state rather than the native state that is dependent on pH. On the basis of the lower stability of the intermediate in the H74A and H185F mutants compared to that of the wild type, we conclude that both His74 and His185 are involved in triggering the pH changes to the conformational stability of wild-type CLIC1 via their protonation, which stabilizes the intermediate state.
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Affiliation(s)
- Ikechukwu Achilonu
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
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32
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Moore SJ, Fisher MG, Yano M, Tong CC, Gale PA. A synergistic approach to anion antiport. Dalton Trans 2011; 40:12017-20. [DOI: 10.1039/c1dt10213c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Moore SJ, Fisher MG, Yano M, Tong CC, Gale PA. A dual host approach to transmembrane transport of salts. Chem Commun (Camb) 2011; 47:689-91. [DOI: 10.1039/c0cc04430j] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Averaimo S, Milton RH, Duchen MR, Mazzanti M. Chloride intracellular channel 1 (CLIC1): Sensor and effector during oxidative stress. FEBS Lett 2010; 584:2076-84. [PMID: 20385134 DOI: 10.1016/j.febslet.2010.02.073] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/28/2010] [Accepted: 02/01/2010] [Indexed: 01/24/2023]
Abstract
Oxidative stress, characterized by overproduction of reactive oxygen species (ROS), is a major feature of several pathological states. Indeed, many cancers and neurodegenerative diseases are accompanied by altered redox balance, which results from dysregulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. In this review, we consider the role of the intracellular chloride channel 1 (CLIC1) in microglial cells during oxidative stress. Following microglial activation, CLIC1 translocates from the cytosol to the plasma membrane where it promotes a chloride conductance. The resultant anionic current balances the excess charge extruded by the active NADPH oxidase, supporting the generation of superoxide by the enzyme. In this scenario, CLIC1 could be considered to act as both a second messenger and an executor.
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Affiliation(s)
- Stefania Averaimo
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università di Milano, Via Celoria 26, 20133 Milan, Italy.
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35
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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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36
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37
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Stoychev SH, Nathaniel C, Fanucchi S, Brock M, Li S, Asmus K, Woods VL, Dirr HW. Structural dynamics of soluble chloride intracellular channel protein CLIC1 examined by amide hydrogen-deuterium exchange mass spectrometry. Biochemistry 2009; 48:8413-21. [PMID: 19650640 PMCID: PMC2752679 DOI: 10.1021/bi9010607] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chloride intracellular channel protein 1 (CLIC1) functions as an anion channel in plasma and nuclear membranes when its soluble monomeric form converts to an integral-membrane form. The transmembrane region of CLIC1 is located in its thioredoxin-like domain 1, but the mechanism whereby the protein converts to its membrane conformation has yet to be determined. Since channel formation in membranes is enhanced at low pH (5 to 5.5), a condition that is found at the surface of membranes, the structural dynamics of soluble CLIC1 was studied at pH 7 and at pH 5.5 in the absence of membranes by amide hydrogen-deuterium exchange mass spectrometry (DXMS). Rapid hydrogen exchange data indicate that CLIC1 displays a similar core structure at these pH values. Domain 1 is less stable than the all-helical domain 2, and, while the structure of domain 1 remains intact, its conformational flexibility is further increased in an acidic environment (pH 5.5). In the absence of membrane, an acidic environment appears to prime the solution structure of CLIC1 by destabilizing domain 1 in order to lower the activation energy barrier for its conversion to the membrane-insertion conformation. The significantly enhanced H/D-exchange rates at pH 5.5 displayed by two segments (peptides 11-31 and 68-82) could be due to the protonation of acidic residues in salt bridges. One of these segments (peptide 11-31) includes part of the transmembrane region which, in the solution structure, consists of helix alpha1. This helix is intrinsically stable and is most likely retained in the membrane conformation. Strand beta2, another element of the transmembrane region, displays a propensity to form a helical structure and has putative N- and C-capping motifs, suggesting that it too most likely forms a helix in a lipid bilayer.
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Affiliation(s)
- Stoyan H. Stoychev
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 250, South Africa
| | - Christos Nathaniel
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 250, South Africa
| | - Sylvia Fanucchi
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 250, South Africa
| | - Melissa Brock
- Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego. 9500 Gilman Drive, La Jolla CA 920930
| | - Sheng Li
- Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego. 9500 Gilman Drive, La Jolla CA 920930
| | - Kyle Asmus
- Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego. 9500 Gilman Drive, La Jolla CA 920930
| | - Virgil L. Woods
- Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego. 9500 Gilman Drive, La Jolla CA 920930
| | - Heini W. Dirr
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 250, South Africa
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38
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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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Oxidation promotes insertion of the CLIC1 chloride intracellular channel into the membrane. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:129-38. [DOI: 10.1007/s00249-009-0450-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 03/23/2009] [Accepted: 03/31/2009] [Indexed: 11/26/2022]
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Ulmasov B, Bruno J, Gordon N, Hartnett ME, Edwards JC. Chloride intracellular channel protein-4 functions in angiogenesis by supporting acidification of vacuoles along the intracellular tubulogenic pathway. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1084-96. [PMID: 19197003 DOI: 10.2353/ajpath.2009.080625] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Endothelial cells form capillary tubes through the process of intracellular tubulogenesis. Chloride intracellular channel (CLIC) family proteins have been previously implicated in intracellular tubulogenesis, but their specific role has not been defined. In this study, we show that disruption of the Clic4 gene in mice results in defective angiogenesis in vivo as reflected in a Matrigel plug angiogenesis assay. An angiogenesis defect is also apparent in the retina, both in the decreased spontaneous development of retinal vasculature of unstressed mice and in the dramatically decreased angiogenic response of retinal vessels to an oxygen toxicity challenge. We found that endothelial cells derived from Clic4(-/-) mice demonstrated impaired tubulogenesis in three-dimensional fibrin gels compared with cells derived from wild-type mice. Furthermore, we found that tubulogenesis of wild-type cells in culture was inhibited by both an inhibitor of CLICs and an inhibitor of the vacuolar proton ATPase. Finally, we showed that vacuoles along the endothelial tubulogenesis pathway are acidic in wild-type cells, and that vacuolar acidification is impaired in Clic4(-/-) cells while lysosomal acidification is intact. We conclude that CLIC4 plays a critical role in angiogenesis by supporting acidification of vacuoles along the cell-hollowing tubulogenic pathway.
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Affiliation(s)
- Barbara Ulmasov
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27514-7155, USA
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Meng X, Wang G, Viero C, Wang Q, Mi W, Su XD, Wagenknecht T, Williams AJ, Liu Z, Yin CC. CLIC2-RyR1 interaction and structural characterization by cryo-electron microscopy. J Mol Biol 2009; 387:320-34. [PMID: 19356589 DOI: 10.1016/j.jmb.2009.01.059] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Revised: 01/18/2009] [Accepted: 01/27/2009] [Indexed: 11/18/2022]
Abstract
Chloride intracellular channel 2 (CLIC2), a newly discovered small protein distantly related to the glutathione transferase (GST) structural family, is highly expressed in cardiac and skeletal muscle, although its physiological function in these tissues has not been established. In the present study, [3H]ryanodine binding, Ca2+ efflux from skeletal sarcoplasmic reticulum (SR) vesicles, single channel recording, and cryo-electron microscopy were employed to investigate whether CLIC2 can interact with skeletal ryanodine receptor (RyR1) and modulate its channel activity. We found that: (1) CLIC2 facilitated [3H]ryanodine binding to skeletal SR and purified RyR1, by increasing the binding affinity of ryanodine for its receptor without significantly changing the apparent maximal binding capacity; (2) CLIC2 reduced the maximal Ca2+ efflux rate from skeletal SR vesicles; (3) CLIC2 decreased the open probability of RyR1 channel, through increasing the mean closed time of the channel; (4) CLIC2 bound to a region between domains 5 and 6 in the clamp-shaped region of RyR1; (5) and in the same clamp region, domains 9 and 10 became separated after CLIC2 binding, indicating CLIC2 induced a conformational change of RyR1. These data suggest that CLIC2 can interact with RyR1 and modulate its channel activity. We propose that CLIC2 functions as an intrinsic stabilizer of the closed state of RyR channels.
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Affiliation(s)
- Xing Meng
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
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Henriksen K, Sørensen MG, Jensen VK, Dziegiel MH, Nosjean O, Karsdal MA. Ion transporters involved in acidification of the resorption lacuna in osteoclasts. Calcif Tissue Int 2008; 83:230-42. [PMID: 18787885 DOI: 10.1007/s00223-008-9168-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 07/31/2008] [Indexed: 10/21/2022]
Abstract
Osteoclasts possess a large amount of ion transporters, which participate in bone resorption; of these, the vacuolar-adenosine trisphosphatase (V-ATPase) and the chloride-proton antiporter ClC-7 acidify the resorption lacuna. However, whether other ion transporters participate in this process is currently not well understood. We used a battery of ion channel inhibitors, human osteoclasts, and their subcellular compartments to perform an unbiased analysis of the importance of the different ion transporters for acidification of the resorption lacuna in osteoclasts. CD14(+) monocytes from human peripheral blood were isolated, and mature osteoclasts were generated using RANKL and M-CSF. The human osteoclasts were (1) used for acridine orange assays for evaluation of lysosomal acidification, (2) used for bone resorption assays, (3) used for generation of osteoclasts membranes for acid influx experiments, or (4) lysed in trizol for mRNA isolation for Affymetrix array analysis. Inhibitors targeted toward most of the ion transporters showed low potency in the acidification-based assays, although some inhibitors, such as carbonic anhydrase II and the sodium-hydrogen exchanger (NHE) inhibitors, reduced resorption potently. In contrast, inhibitors targeted at V-ATPase and ClC-7 potently inhibited both acidification and resorption, as expected. We here show evidence that acidification of the resorption lacuna is mainly mediated by V-ATPase and ClC-7. Furthermore, a group of other ion transporters, including carbonic anhydrase II, the NHEs, and potassium-chloride cotransporters, are all involved in resorption but do not seem to directly be involved in acidification of the lysosomes.
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Affiliation(s)
- Kim Henriksen
- Nordic Bioscience A/S, Herlev Hovedgade 207, 2730 Herlev, Denmark.
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Abstract
Proteomics has evolved, in recent years, into effective tools for basic and applied stem cell research, and has been extensively used to facilitate the identification of changes in signal transduction components, especially with regard to plasticity, proliferation, and differentiation. Several recent reports have also employed proteomic strategies to characterize human mesenchymal stem cells (hMSC) and their differentiated derivatives. Although these approaches have yielded valuable data, the results highlight the fact that only the limited numbers of proteins are characterized at the protein level in these cells, thus necessitating expandable MSC proteome dataset. This review presents, for the first time, an expandable list of MSC proteins, which will function as a starting point for the generation of a comprehensive reference map of their proteome. Also, the better way to bridge current gap between genomics and proteomics study such as integrated proteomic and transcriptomic analyses is discussed.
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Affiliation(s)
- Hye Won Park
- School of Life Sciences and Biotechnology, Korea University, Seoul, Korea
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Cromer BA, Gorman MA, Hansen G, Adams JJ, Coggan M, Littler DR, Brown LJ, Mazzanti M, Breit SN, Curmi PM, Dulhunty AF, Board PG, Parker MW. Structure of the Janus Protein Human CLIC2. J Mol Biol 2007; 374:719-31. [DOI: 10.1016/j.jmb.2007.09.041] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 09/12/2007] [Accepted: 09/12/2007] [Indexed: 10/22/2022]
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Ducharme G, Newell EW, Pinto C, Schlichter LC. Small-conductance Cl- channels contribute to volume regulation and phagocytosis in microglia. Eur J Neurosci 2007; 26:2119-30. [PMID: 17927776 DOI: 10.1111/j.1460-9568.2007.05802.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The shape and volume of microglia (brain immune cells) change when they activate during brain inflammation and become migratory and phagocytic. Swollen rat microglia express a large Cl(-) current (I(Clswell)), whose biophysical properties and functional roles are poorly understood and whose molecular identity is unknown. We constructed a fingerprint of useful biophysical properties for comparison with I(Clswell) in other cell types and with cloned Cl(-) channels. The microglial I(Clswell) was rapidly activated by cell swelling but not by voltage, and showed no time-dependence during voltage-clamp steps. Like I(Clswell) in many cell types, the halide selectivity sequence was I(-) > Br(-) > Cl(-) > F(-). However, it differed in lacking inactivation, even at +100 mV with high extracellular Mg(2+), and in having a much lower single-channel conductance: 1-3 pS. Based on these fundamental differences, the microglia channel is apparently a different gene product than the more common intermediate-conductance I(Clswell). Microglia express several candidate genes, with relative mRNA expression levels of: CLIC1 > ClC3 > I(Cln) > or = ClC2 > Best2 > Best1 > or = Best3 > Best4. Using a pharmacological toolbox, we show that all drugs that reduced the microglia current (NPPB, IAA-94, flufenamic acid and DIOA) increased the resting cell volume in isotonic solution and inhibited the regulatory volume decrease that followed cell swelling in hypotonic solution. Both channel blockers tested (NPPB and flufenamic acid) dose-dependently inhibited microglia phagocytosis of E. coli bacteria. Because I(Clswell) is involved in microglia functions that involve shape and volume changes, it is potentially important for controlling their ability to migrate to damage sites and phagocytose dead cells and debris.
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Affiliation(s)
- Guillaume Ducharme
- Toronto Western Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada M5T 2S8
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Pluder F, Sinz A, Beck-Sickinger AG. Proliferative effect of calcitonin gene-related peptide is induced by at least five proteins as identified by proteome profiling. Chem Biol Drug Des 2007; 69:14-22. [PMID: 17313453 DOI: 10.1111/j.1747-0285.2007.00466.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Calcitonin gene-related peptide is a 37 amino acid neuropeptide. Although calcitonin gene-related peptide activates a G-protein-coupled receptor, recent evidence suggests that calcitonin gene-related peptide induces more complex signaling cascades including the activation of MAP kinases [Eur J Pharmacol; 389:125-130 (2000), Neuropeptides; 34:229-233 (2000)]. However, the molecular mechanisms of this activation still remain to be elucidated. For the first time we applied a proteomics approach in order to identify molecular targets of calcitonin gene-related peptide downstream signaling in the neuroblastoma cell line SK-N-MC and identified proteins that changed either their expression, location, or their post-translational modifications in a time-dependent manner after calcitonin gene-related peptide stimulation.
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Affiliation(s)
- Franka Pluder
- Institute of Biochemistry, Faculty of Bioscience, Pharmacy and Psychology, University of Leipzig, Brüderstrasse 34, D-04103 Leipzig, Germany
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47
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Edwards JC. The CLIC1 chloride channel is regulated by the cystic fibrosis transmembrane conductance regulator when expressed in Xenopus oocytes. J Membr Biol 2007; 213:39-46. [PMID: 17347778 PMCID: PMC2665869 DOI: 10.1007/s00232-006-0059-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Revised: 10/03/2006] [Indexed: 10/23/2022]
Abstract
CLIC proteins comprise a family of chloride channels whose physiological roles are uncertain. To gain further insight into possible means of CLIC1 channel activity regulation, this protein was expressed in Xenopus oocytes alone or in combination with the cystic fibrosis transmembrane conductance regulator (CFTR). Whole-cell currents were determined using two-electrode voltage-clamp methods. Expression of CLIC1 alone did not increase whole-cell conductance either at rest or in response to increased intracellular cyclic adenosine monophosphate (cAMP). However, expression of CLIC1 with CFTR led to increased cAMP-activated whole-cell currents compared to expression from the same amount of CFTR mRNA alone. IAA-94 is a drug known to inhibit CLIC family channels but not CFTR. In oocytes expressing both CLIC1 and CFTR, a fraction of the cAMP-activated whole-cell current was sensitive to IAA-94, whereas in oocytes expressing CFTR alone, the cAMP-stimulated current was resistant to the drug. Cell fractionation studies revealed that the presence of CFTR conferred cAMP-stimulated redistribution of a fraction of CLIC1 from a soluble to a membrane-associated form. We conclude that when expressed in Xenopus oocytes CFTR confers cAMP regulation to CLIC1 activity in the plasma membrane and that at least part of this regulation is due to recruitment of CLIC1 from the cytoplasm to the membrane.
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Affiliation(s)
- John C Edwards
- UNC Kidney Center and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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48
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Abstract
Background CLIC1 is a chloride channel whose cellular role remains uncertain. The distribution of CLIC1 in normal tissues is largely unknown and conflicting data have been reported regarding the cellular membrane fraction in which CLIC1 resides. Results New antisera to CLIC1 were generated and were found to be sensitive and specific for detecting this protein. These antisera were used to investigate the distribution of CLIC1 in mouse tissue sections and three cultured cell lines. We find CLIC1 is expressed in the apical domains of several simple columnar epithelia including glandular stomach, small intestine, colon, bile ducts, pancreatic ducts, airway, and the tail of the epididymis, in addition to the previously reported renal proximal tubule. CLIC1 is expressed in a non-polarized distribution in the basal epithelial cell layer of the stratified squamous epithelium of the upper gastrointesitinal tract and the basal cells of the epididymis, and is present diffusely in skeletal muscle. Distribution of CLIC1 was examined in Panc1 cells, a relatively undifferentiated, non-polarized human cell line derived from pancreatic cancer, and T84 cells, a human colon cancer cell line which can form a polarized epithelium that is capable of regulated chloride transport. Digitonin extraction was used to distinguish membrane-inserted CLIC1 from the soluble cytoplasmic form of the protein. We find that digitonin-resistant CLIC1 is primarily present in the plasma membrane of Panc1 cells. In T84 cells, we find digitonin-resistant CLIC1 is present in an intracellular compartment which is concentrated immediately below the apical plasma membrane and the extent of apical polarization is enhanced with forskolin, which activates transepithelial chloride transport and apical membrane traffic in these cells. The sub-apical CLIC1 compartment was further characterized in a well-differentiated mouse renal proximal tubule cell line. The distribution of CLIC1 was found to overlap that of megalin and the sodium-phosphate cotransporter, NaPi-II, which are markers of the apical endocytic/recycling compartment in proximal tubule. Conclusion The cell and tissue specific patterns of CLIC1 expression suggest it may play distinct roles in different cell types. In certain polarized columnar epithelia, it may play a role in apical membrane recycling.
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Sun HJ, Bahk YY, Choi YR, Shim JH, Han SH, Lee JW. A proteomic analysis during serial subculture and osteogenic differentiation of human mesenchymal stem cell. J Orthop Res 2006; 24:2059-71. [PMID: 16947300 DOI: 10.1002/jor.20273] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although previous studies have reported the effects of extensive subculturing on proliferation rates and osteogenic potential of human mesenchymal stem cells (hMSCs), the results remain controversial. The aim of our study was to characterize the proliferation and osteogenic potential of hMSCs during serial subculture, and also to identify proteins that are differentially regulated in hMSCs during serial subculture and osteogenic differentiation using proteome analysis. Here we show that the proliferation and osteogenic capacity of hMSCs decrease during serial subculturing. Several proteins were shown to be differentially regulated during serial subculture; among these the expression of T-complex protein 1 alpha subunit (TCP-1alpha), a protein known to be associated with cell proliferation, cell cycle, morphological changes, and apoptosis, gradually decreased during serial subculture. Among proteins that were differentially regulated during osteogenic differentiation, chloride intracellular channel 1 (CLIC1) was downregulated only during the early passages eukaryotic translation elongation factor, and acidic ribosomal phosphoprotein P0 was downregulated during the middle passages, while annexin V, LIM, and SH3 domain protein 1 (LASP-1), and 14-3-3 protein gamma (YWHAG) were upregulated during the later passage. These studies suggest that differentially regulated passage-specific proteins may play a role in the decrease of osteogenic differentiation potential under serial subculturing.
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Affiliation(s)
- Hyun Jin Sun
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea
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Shield AJ, Murray TP, Board PG. Functional characterisation of ganglioside-induced differentiation-associated protein 1 as a glutathione transferase. Biochem Biophys Res Commun 2006; 347:859-66. [PMID: 16857173 DOI: 10.1016/j.bbrc.2006.06.189] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 06/21/2006] [Indexed: 11/26/2022]
Abstract
Mutations in the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene have been linked with Charcot-Marie-Tooth (CMT) disease. This protein, and its paralogue GDAP1L1, appear to be structurally related to the cytosolic glutathione S-transferases (GST) including an N-terminal thioredoxin fold domain with conserved active site residues. The specific function, of GDAP1 remains unknown. To further characterise their structure and function we purified recombinant human GDAP1 and GDAP1L1 proteins using bacterial expression and immobilised metal affinity chromatography. Like other cytosolic GSTs, GDAP1 protein has a dimeric structure. Although the full-length proteins were largely insoluble, the deletion of a proposed C-terminal transmembrane domain allowed the preparation of soluble protein. The purified proteins were assayed for glutathione-dependent activity against a library of 'prototypic' GST substrates. No evidence of glutathione-dependent activity or an ability to bind glutathione immobilised on agarose was found.
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Affiliation(s)
- Alison J Shield
- Molecular Genetics Group, Division of Molecular Biosciences, John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601, Australia
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