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Gezdirici A, Kalaycik Şengül Ö, Doğan M, Özgüven BY, Akbulut E. Biallelic Novel USP53 Splicing Variant Disrupting the Gene Function that Causes Cholestasis Phenotype and Review of the Literature. Mol Syndromol 2023; 13:471-484. [PMID: 36660033 PMCID: PMC9843568 DOI: 10.1159/000523937] [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: 08/11/2021] [Accepted: 03/02/2022] [Indexed: 01/22/2023] Open
Abstract
Introduction Hereditary cholestasis is a heterogeneous group of liver diseases that mostly show autosomal recessive inheritance. The phenotype of cholestasis is highly variable. Molecular genetic testing offers an useful approach to differentiate different types of cholestasis because some symptoms and findings overlap. Biallelic variants in USP53 have recently been reported in cholestasis phenotype. Methods In this study, we aimed to characterize clinical findings and biological insights on a novel USP53 splice variant causing cholestasis phenotype and provided a review of the literature. We performed whole-exome sequencing and then confirmed it with Sanger sequencing. In addition, as a result of in silico analyses and cDNA analysis, we showed that the USP53 protein in our patient was shortened. Results We report a novel splice variant (NM_019050.2:c.238-1G>C) in the USP53 gene via whole-exome sequencing in a patient with cholestasis phenotype. This variant was confirmed by Sanger sequencing and was a result of family segregation analysis; it was found to be in a heterozygous state in the parents and the other healthy elder brother of our patient. According to in silico analyses, the change in the splice region resulted in an increase in the length of exon 2, whereas the stop codon after the additional 3 amino acids (VTF) caused the protein to terminate prematurely. Thus, the mature USP53 protein, consisting of 1,073 amino acids, has been reduced to a small protein of 82 amino acids. Conclusion We propose a model for the tertiary structure of USP53 for the first time, and together with all these data, we support the association of biallelic variants of the USP53 gene with cholestasis phenotype. We also present a comparison of previously reported patients with USP53-associated cholestasis phenotype to contribute to the literature.
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Affiliation(s)
- Alper Gezdirici
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey,*Alper Gezdirici,
| | - Özlem Kalaycik Şengül
- Department of Pediatric Gastroenterology, Hepatology and Nutrition, Kanuni Sultan Suleyman Training and Research Hospital, Istanbul, Turkey
| | - Mustafa Doğan
- Department of Medical Genetics, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Banu Y. Özgüven
- Department of Pathology, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Ekrem Akbulut
- Department of Bioengineering, Malatya Turgut Ozal University, Malatya, Turkey
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2
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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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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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Archanjo AB, Assis ALEMD, Oliveira MMD, Mendes SO, Borçoi AR, Maia LDL, Souza RPD, Cicco RD, Saito KC, Kimura ET, Carvalho MBD, Nunes FD, Tajara EH, Santos MD, Nogueira BV, Trivilin LO, Pinheiro CJG, Álvares-da-Silva AM. Elemental characterization of oral cavity squamous cell carcinoma and its relationship with smoking, prognosis and survival. Sci Rep 2020; 10:10382. [PMID: 32587307 PMCID: PMC7316707 DOI: 10.1038/s41598-020-67270-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 06/03/2020] [Indexed: 11/29/2022] Open
Abstract
Oral cancer squamous cell carcinoma (OCSCC) mainly affects individuals aged between 50 and 70 years who consume tobacco and alcohol. Tobacco smoke contains hundreds of known toxic and carcinogenic molecules, and a few studies have sought to verify the relationship of such trace elements as risk or prognostic factors for head and neck cancer. We obtained 78 samples of tumor tissues from patients with OCSCC, and performed a qualitative elemental characterization using the micro X-Ray Fluorescence technique based on synchrotron radiation. We found the presence of magnesium, phosphorus, sulfur, chlorine, potassium, calcium, chromium, manganese, iron, zinc, cobalt, nickel, copper, arsenic and bromine in OCSCC samples. Magnesium, chlorine, chromium, manganese, nickel, arsenic and bromine are associated with smoking. We observed a significant association between relapse and chlorine and chromium. The presence of chlorine in the samples was an independent protective factor against relapse (OR = 0.105, CI = 0.01-0.63) and for best disease-free survival (HR = 0.194, CI = 0.04-0.87). Reporting for the first time in oral cancer, these results suggest a key relationship between smoking and the presence of certain elements. In addition, chlorine proved to be important in the context of patient prognosis and survival.
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Affiliation(s)
- Anderson Barros Archanjo
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil.
| | | | - Mayara Mota de Oliveira
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
| | - Suzanny Oliveira Mendes
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
| | - Aline Ribeiro Borçoi
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
| | - Lucas de Lima Maia
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
| | | | - Rafael de Cicco
- Cancer Institute Arnaldo Vieira de Carvalho, São Paulo, Brazil
| | | | - Edna Teruko Kimura
- Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | | | | | - Eloiza H Tajara
- Medical School of São José do Rio Preto, São José do Rio Preto, Brazil
| | - Marcelo Dos Santos
- Multicampi School of Medical Sciences of Rio Grande do Norte, Federal University of Rio Grande do Norte, Caicó, Brazil
| | - Breno Valentim Nogueira
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
| | | | | | - Adriana Madeira Álvares-da-Silva
- Postgraduate Program in Biotechnology/RENORBIO, Federal University of Espirito Santo, Av. Marechal Campos, 1468, Vitoria, 29.040-090, ES, Brazil
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Peterman E, Valius M, Prekeris R. CLIC4 is a cytokinetic cleavage furrow protein that regulates cortical cytoskeleton stability during cell division. J Cell Sci 2020; 133:jcs241117. [PMID: 32184265 PMCID: PMC7240295 DOI: 10.1242/jcs.241117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 03/02/2020] [Indexed: 12/31/2022] Open
Abstract
During mitotic cell division, the actomyosin cytoskeleton undergoes several dynamic changes that play key roles in progression through mitosis. Although the regulators of cytokinetic ring formation and contraction are well established, proteins that regulate cortical stability during anaphase and telophase have been understudied. Here, we describe a role for CLIC4 in regulating actin and actin regulators at the cortex and cytokinetic cleavage furrow during cytokinesis. We first describe CLIC4 as a new component of the cytokinetic cleavage furrow that is required for successful completion of mitotic cell division. We also demonstrate that CLIC4 regulates the remodeling of the sub-plasma-membrane actomyosin network within the furrow by recruiting MST4 kinase (also known as STK26) and regulating ezrin phosphorylation. This work identifies and characterizes new molecular players involved in regulating cortex stiffness and blebbing during the late stages of cytokinetic furrowing.
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Affiliation(s)
- Eric Peterman
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mindaugas Valius
- Proteomics Center, Institute of Biochemistry, Vilnius University Life Sciences Center, Vilnius 10257, Lithuania
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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The Flemmingsome reveals an ESCRT-to-membrane coupling via ALIX/syntenin/syndecan-4 required for completion of cytokinesis. Nat Commun 2020; 11:1941. [PMID: 32321914 PMCID: PMC7176721 DOI: 10.1038/s41467-020-15205-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 02/21/2020] [Indexed: 12/29/2022] Open
Abstract
Cytokinesis requires the constriction of ESCRT-III filaments on the side of the midbody, where abscission occurs. After ESCRT recruitment at the midbody, it is not known how the ESCRT-III machinery localizes to the abscission site. To reveal actors involved in abscission, we obtained the proteome of intact, post-abscission midbodies (Flemmingsome) and identified 489 proteins enriched in this organelle. Among these proteins, we further characterized a plasma membrane-to-ESCRT module composed of the transmembrane proteoglycan syndecan-4, ALIX and syntenin, a protein that bridges ESCRT-III/ALIX to syndecans. The three proteins are highly recruited first at the midbody then at the abscission site, and their depletion delays abscission. Mechanistically, direct interactions between ALIX, syntenin and syndecan-4 are essential for proper enrichment of the ESCRT-III machinery at the abscission site, but not at the midbody. We propose that the ESCRT-III machinery must be physically coupled to a membrane protein at the cytokinetic abscission site for efficient scission, uncovering common requirements in cytokinesis, exosome formation and HIV budding.
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Gururaja Rao S, Patel NJ, Singh H. Intracellular Chloride Channels: Novel Biomarkers in Diseases. Front Physiol 2020; 11:96. [PMID: 32116799 PMCID: PMC7034325 DOI: 10.3389/fphys.2020.00096] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/27/2020] [Indexed: 12/27/2022] Open
Abstract
Ion channels are integral membrane proteins present on the plasma membrane as well as intracellular membranes. In the human genome, there are more than 400 known genes encoding ion channel proteins. Ion channels are known to regulate several cellular, organellar, and physiological processes. Any mutation or disruption in their function can result in pathological disorders, both common or rare. Ion channels present on the plasma membrane are widely acknowledged for their role in various biological processes, but in recent years, several studies have pointed out the importance of ion channels located in intracellular organelles. However, ion channels located in intracellular organelles are not well-understood in the context of physiological conditions, such as the generation of cellular excitability and ionic homeostasis. Due to the lack of information regarding their molecular identity and technical limitations of studying them, intracellular organelle ion channels have thus far been overlooked as potential therapeutic targets. In this review, we focus on a novel class of intracellular organelle ion channels, Chloride Intracellular Ion Channels (CLICs), mainly documented for their role in cardiovascular, neurophysiology, and tumor biology. CLICs have a single transmembrane domain, and in cells, they exist in cytosolic as well as membranous forms. They are predominantly present in intracellular organelles and have recently been shown to be localized to cardiomyocyte mitochondria as well as exosomes. In fact, a member of this family, CLIC5, is the first mitochondrial chloride channel to be identified on the molecular level in the inner mitochondrial membrane, while another member, CLIC4, is located predominantly in the outer mitochondrial membrane. In this review, we discuss this unique class of intracellular chloride channels, their role in pathologies, such as cardiovascular, cancer, and neurodegenerative diseases, and the recent developments concerning their usage as theraputic targets.
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Affiliation(s)
- Shubha Gururaja Rao
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Neel J Patel
- Department of Cardiology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States
| | - Harpreet Singh
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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8
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Uretmen Kagiali ZC, Saner N, Akdag M, Sanal E, Degirmenci BS, Mollaoglu G, Ozlu N. CLIC4 and CLIC1 bridge plasma membrane and cortical actin network for a successful cytokinesis. Life Sci Alliance 2019; 3:3/2/e201900558. [PMID: 31879279 PMCID: PMC6933522 DOI: 10.26508/lsa.201900558] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 11/24/2022] Open
Abstract
CLIC members are required for the progression of cytokinesis by coupling the plasma membrane and cortical actin network at the cleavage furrow and polar cortex. CLIC4 and CLIC1 are members of the well-conserved chloride intracellular channel proteins (CLICs) structurally related to glutathione-S-transferases. Here, we report new roles of CLICs in cytokinesis. At the onset of cytokinesis, CLIC4 accumulates at the cleavage furrow and later localizes to the midbody in a RhoA-dependent manner. The cell cycle–dependent localization of CLIC4 is abolished when its glutathione S-transferase activity–related residues (C35A and F37D) are mutated. Ezrin, anillin, and ALIX are identified as interaction partners of CLIC4 at the cleavage furrow and midbody. Strikingly, CLIC4 facilitates the activation of ezrin at the cleavage furrow and reciprocally inhibition of ezrin activation diminishes the translocation of CLIC4 to the cleavage furrow. Furthermore, knockouts of CLIC4and CLIC1 cause abnormal blebbing at the polar cortex and regression of the cleavage furrow at late cytokinesis leading to multinucleated cells. We conclude that CLIC4 and CLIC1 function together with ezrin where they bridge plasma membrane and actin cytoskeleton at the polar cortex and cleavage furrow to promote cortical stability and successful completion of cytokinesis in mammalian cells.
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Affiliation(s)
| | - Nazan Saner
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Mehmet Akdag
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Erdem Sanal
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | | | - Gurkan Mollaoglu
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Nurhan Ozlu
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey .,Koç University Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey
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Zhu YR, Jiang XX, Zheng Y, Xiong J, Wei D, Zhang DM. Cardiac function modulation depends on the A-kinase anchoring protein complex. J Cell Mol Med 2019; 23:7170-7179. [PMID: 31512389 PMCID: PMC6815827 DOI: 10.1111/jcmm.14659] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/27/2019] [Accepted: 08/06/2019] [Indexed: 12/26/2022] Open
Abstract
The A‐kinase anchoring proteins (AKAPs) are a group of structurally diverse proteins identified in various species and tissues. These proteins are able to anchor protein kinase and other signalling proteins to regulate cardiac function. Acting as a scaffold protein, AKAPs ensure specificity in signal transduction by enzymes close to their appropriate effectors and substrates. Over the decades, more than 70 different AKAPs have been discovered. Accumulative evidence indicates that AKAPs play crucial roles in the functional regulation of cardiac diseases, including cardiac hypertrophy, myofibre contractility dysfunction and arrhythmias. By anchoring different partner proteins (PKA, PKC, PKD and LTCCs), AKAPs take part in different regulatory pathways to function as regulators in the heart, and a damaged structure can influence the activities of these complexes. In this review, we highlight recent advances in AKAP‐associated protein complexes, focusing on local signalling events that are perturbed in cardiac diseases and their roles in interacting with ion channels and their regulatory molecules. These new findings suggest that AKAPs might have potential therapeutic value in patients with cardiac diseases, particularly malignant rhythm.
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Affiliation(s)
- Yan-Rong Zhu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Xiao-Xin Jiang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yaguo Zheng
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Jing Xiong
- Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Dongping Wei
- Department of Oncology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
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Ueno Y, Ozaki S, Umakoshi A, Yano H, Choudhury ME, Abe N, Sumida Y, Kuwabara J, Uchida R, Islam A, Ogawa K, Ishimaru K, Yorozuya T, Kunieda T, Watanabe Y, Takada Y, Tanaka J. Chloride intracellular channel protein 2 in cancer and non-cancer human tissues: relationship with tight junctions. Tissue Barriers 2019; 7:1593775. [PMID: 30929599 PMCID: PMC6592591 DOI: 10.1080/21688370.2019.1593775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Chloride intracellular channel protein 2 (CLIC2) belongs to the CLIC family of conserved metazoan proteins. Although CLICs have been identified as chloride channels, they are currently considered multifunctional proteins. CLIC2 is the least studied family member. We investigated CLIC2 expression and localization in human hepatocellular carcinoma, metastatic colorectal cancer in the liver, and colorectal cancer. Significant expression of mRNAs encoding CLIC1, 2, 4, and 5 were found in the human tissues, but only CLIC2 was predominantly expressed in non-cancer tissues surrounding cancer masses. Fibrotic or dysfunctional (aspartate aminotransferase ≥40) non-cancer liver tissues and advanced stage HCC tissues expressed low levels of CLIC2. Endothelial cells lining blood vessels but not lymphatic vessels in non-cancer tissues expressed CLIC2 as well as high levels of the tight junction proteins claudins 1 and 5, occludin, and ZO-1. Most endothelial cells in blood vessels in cancer tissues had very low expressions of CLIC2 and tight junction proteins. CD31+/CD45− endothelial cells isolated from non-cancer tissues expressed mRNAs encoding CLIC2, claudin 1, occludin and ZO-1, while similar cell fractions from cancer tissues had very low expressions of these molecules. Knockdown of CLIC2 expression in human umbilical vein endothelial cells (HUVECs) allowed human cancer cells to transmigrate through a HUVEC monolayer. These results suggest that CLIC2 may be involved in the formation and/or maintenance of tight junctions and that cancer tissue vasculature lacks CLIC2 and tight junctions, which allows the intravasation of cancer cells necessary for hematogenous metastasis.
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Affiliation(s)
- Yoshitomo Ueno
- a Department of Hepato-biliary Pancreatic Surgery and Breast Surgery, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Saya Ozaki
- b Department of Neurosurgery, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Akihiro Umakoshi
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Hajime Yano
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Mohammed E Choudhury
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Naoki Abe
- d Department of Anesthesia and Perioperative Medicine, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Yutaro Sumida
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Jun Kuwabara
- e Department of Gastrointestinal Surgery and Surgical Oncology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Rina Uchida
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Afsana Islam
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Kohei Ogawa
- a Department of Hepato-biliary Pancreatic Surgery and Breast Surgery, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Kei Ishimaru
- e Department of Gastrointestinal Surgery and Surgical Oncology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Toshihiro Yorozuya
- d Department of Anesthesia and Perioperative Medicine, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Takeharu Kunieda
- b Department of Neurosurgery, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Yuji Watanabe
- e Department of Gastrointestinal Surgery and Surgical Oncology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Yasutsugu Takada
- a Department of Hepato-biliary Pancreatic Surgery and Breast Surgery, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
| | - Junya Tanaka
- c Department of Molecular and Cellular Physiology, Graduate School of Medicine , Ehime University , Toon , Ehime , Japan
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Huang MC, Chu IT, Wang ZF, Lin S, Chang TC, Chen CT. A G-Quadruplex Structure in the Promoter Region of CLIC4 Functions as a Regulatory Element for Gene Expression. Int J Mol Sci 2018; 19:ijms19092678. [PMID: 30201851 PMCID: PMC6165315 DOI: 10.3390/ijms19092678] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/25/2022] Open
Abstract
The differential transcriptional expression of CLIC4 between tumor cells and the surrounding stroma during cancer progression has been suggested to have a tumor-promoting effect. However, little is known about the transcriptional regulation of CLIC4. To better understand how this gene is regulated, the promoter region of CLIC4 was analyzed. We found that a high GC content near the transcriptional start site (TSS) might form an alternative G-quadruplex (G4) structure. Nuclear magnetic resonance spectroscopy (NMR) confirmed their formation in vitro. The reporter assay showed that one of the G4 structures exerted a regulatory role in gene transcription. When the G4-forming sequence was mutated to disrupt the G4 structure, the transcription activity dropped. To examine whether this G4 structure actually has an influence on gene transcription in the chromosome, we utilized the CRISPR/Cas9 system to edit the G4-forming sequence within the CLIC4 promoter in the cell genome. The pop-in/pop-out strategy was adopted to isolate the precisely-edited A375 cell clone. In CRISPR-modified A375 cell clones whose G4 was disrupted, there was a decrease in the endogenous CLIC4 messenger RNA (mRNA) expression level. In conclusion, we found that the G4 structure in the CLIC4 promoter might play an important role in regulating the level of transcription.
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Affiliation(s)
- Mu-Ching Huang
- Department of Biochemical Science and Technology, National Taiwan University, Taipei 106, Taiwan.
| | - I-Te Chu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Zi-Fu Wang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Steven Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
| | - Ta-Chau Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Chin-Tin Chen
- Department of Biochemical Science and Technology, National Taiwan University, Taipei 106, Taiwan.
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12
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Pendleton AL, Shen F, Taravella AM, Emery S, Veeramah KR, Boyko AR, Kidd JM. Comparison of village dog and wolf genomes highlights the role of the neural crest in dog domestication. BMC Biol 2018; 16:64. [PMID: 29950181 PMCID: PMC6022502 DOI: 10.1186/s12915-018-0535-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/23/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Domesticated from gray wolves between 10 and 40 kya in Eurasia, dogs display a vast array of phenotypes that differ from their ancestors, yet mirror other domesticated animal species, a phenomenon known as the domestication syndrome. Here, we use signatures persisting in dog genomes to identify genes and pathways possibly altered by the selective pressures of domestication. RESULTS Whole-genome SNP analyses of 43 globally distributed village dogs and 10 wolves differentiated signatures resulting from domestication rather than breed formation. We identified 246 candidate domestication regions containing 10.8 Mb of genome sequence and 429 genes. The regions share haplotypes with ancient dogs, suggesting that the detected signals are not the result of recent selection. Gene enrichments highlight numerous genes linked to neural crest and central nervous system development as well as neurological function. Read depth analysis suggests that copy number variation played a minor role in dog domestication. CONCLUSIONS Our results identify genes that act early in embryogenesis and can confer phenotypes distinguishing domesticated dogs from wolves, such as tameness, smaller jaws, floppy ears, and diminished craniofacial development as the targets of selection during domestication. These differences reflect the phenotypes of the domestication syndrome, which can be explained by alterations in the migration or activity of neural crest cells during development. We propose that initial selection during early dog domestication was for behavior, a trait influenced by genes which act in the neural crest, which secondarily gave rise to the phenotypes of modern dogs.
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Affiliation(s)
- Amanda L Pendleton
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Feichen Shen
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Angela M Taravella
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Sarah Emery
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Krishna R Veeramah
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Adam R Boyko
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, 14853, USA
| | - Jeffrey M Kidd
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA.
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13
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Argenzio E, Moolenaar WH. Emerging biological roles of Cl- intracellular channel proteins. J Cell Sci 2017; 129:4165-4174. [PMID: 27852828 DOI: 10.1242/jcs.189795] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cl- intracellular channels (CLICs) are a family of six evolutionary conserved cytosolic proteins that exist in both soluble and membrane-associated forms; however, their functions have long been elusive. Soluble CLICs adopt a glutathione S-transferase (GST)-fold, can induce ion currents in artificial membranes and show oxidoreductase activity in vitro, but there is no convincing evidence of CLICs having such activities in vivo. Recent studies have revealed a role for CLIC proteins in Rho-regulated cortical actin dynamics as well as vesicular trafficking and integrin recycling, the latter of which are under the control of Rab GTPases. In this Commentary, we discuss the emerging roles of CLIC proteins in these processes and the lessons learned from gene-targeting studies. We also highlight outstanding questions regarding the molecular function(s) of these important but still poorly understood proteins.
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Affiliation(s)
- Elisabetta Argenzio
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
| | - Wouter H Moolenaar
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands
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14
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Corne TDJ, Sieprath T, Vandenbussche J, Mohammed D, Te Lindert M, Gevaert K, Gabriele S, Wolf K, De Vos WH. Deregulation of focal adhesion formation and cytoskeletal tension due to loss of A-type lamins. Cell Adh Migr 2016; 11:447-463. [PMID: 27791462 DOI: 10.1080/19336918.2016.1247144] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The nuclear lamina mechanically integrates the nucleus with the cytoskeleton and extracellular environment and regulates gene expression. These functions are exerted through direct and indirect interactions with the lamina's major constituent proteins, the A-type lamins, which are encoded by the LMNA gene. Using quantitative stable isotope labeling-based shotgun proteomics we have analyzed the proteome of human dermal fibroblasts in which we have depleted A-type lamins by means of a sustained siRNA-mediated LMNA knockdown. Gene ontology analysis revealed that the largest fraction of differentially produced proteins was involved in actin cytoskeleton organization, in particular proteins involved in focal adhesion dynamics, such as actin-related protein 2 and 3 (ACTR2/3), subunits of the ARP2/3 complex, and fascin actin-bundling protein 1 (FSCN1). Functional validation using quantitative immunofluorescence showed a significant reduction in the size of focal adhesion points in A-type lamin depleted cells, which correlated with a reduction in early cell adhesion capacity and an increased cell motility. At the same time, loss of A-type lamins led to more pronounced stress fibers and higher traction forces. This phenotype could not be mimicked or reversed by experimental modulation of the STAT3-IL6 pathway, but it was partly recapitulated by chemical inhibition of the ARP2/3 complex. Thus, our data suggest that the loss of A-type lamins perturbs the balance between focal adhesions and cytoskeletal tension. This imbalance may contribute to mechanosensing defects observed in certain laminopathies.
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Affiliation(s)
- Tobias D J Corne
- a Laboratory of Cell Biology and Histology , Department of Veterinary Sciences, University of Antwerp , Antwerp , Belgium.,b Cell Systems and Imaging Research Group (CSI) , Department of Molecular Biotechnology, Ghent University , Ghent , Belgium
| | - Tom Sieprath
- a Laboratory of Cell Biology and Histology , Department of Veterinary Sciences, University of Antwerp , Antwerp , Belgium.,b Cell Systems and Imaging Research Group (CSI) , Department of Molecular Biotechnology, Ghent University , Ghent , Belgium
| | - Jonathan Vandenbussche
- c Medical Biotechnology Center, VIB , Belgium.,d Department of Biochemistry , Ghent University , Ghent , Belgium
| | - Danahe Mohammed
- e Mechanobiology & Soft Matter Research Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons , Mons , Belgium
| | - Mariska Te Lindert
- f Department of Cell Biology , Radboud University Medical Center , Nijmegen , The Netherlands
| | - Kris Gevaert
- c Medical Biotechnology Center, VIB , Belgium.,d Department of Biochemistry , Ghent University , Ghent , Belgium
| | - Sylvain Gabriele
- e Mechanobiology & Soft Matter Research Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons , Mons , Belgium
| | - Katarina Wolf
- f Department of Cell Biology , Radboud University Medical Center , Nijmegen , The Netherlands
| | - Winnok H De Vos
- a Laboratory of Cell Biology and Histology , Department of Veterinary Sciences, University of Antwerp , Antwerp , Belgium.,b Cell Systems and Imaging Research Group (CSI) , Department of Molecular Biotechnology, Ghent University , Ghent , Belgium
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15
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Lecat S, Matthes HWD, Pepperkok R, Simpson JC, Galzi JL. A Fluorescent Live Imaging Screening Assay Based on Translocation Criteria Identifies Novel Cytoplasmic Proteins Implicated in G Protein-coupled Receptor Signaling Pathways. Mol Cell Proteomics 2015; 14:1385-99. [PMID: 25759509 PMCID: PMC4424407 DOI: 10.1074/mcp.m114.046698] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/20/2015] [Indexed: 12/13/2022] Open
Abstract
Several cytoplasmic proteins that are involved in G protein-coupled receptor signaling cascades are known to translocate to the plasma membrane upon receptor activation, such as beta-arrestin2. Based on this example and in order to identify new cytoplasmic proteins implicated in the ON-and-OFF cycle of G protein-coupled receptor, a live-imaging screen of fluorescently labeled cytoplasmic proteins was performed using translocation criteria. The screening of 193 fluorescently tagged human proteins identified eight proteins that responded to activation of the tachykinin NK2 receptor by a change in their intracellular localization. Previously we have presented the functional characterization of one of these proteins, REDD1, that translocates to the plasma membrane. Here we report the results of the entire screening. The process of cell activation was recorded on videos at different time points and all the videos can be visualized on a dedicated website. The proteins BAIAP3 and BIN1, partially translocated to the plasma membrane upon activation of NK2 receptors. Proteins ARHGAP12 and PKM2 translocated toward membrane blebs. Three proteins that associate with the cytoskeleton were of particular interest : PLEKHH2 rearranged from individual dots located near the cell-substrate adhesion surface into lines of dots. The speriolin-like protein, SPATC1L, redistributed to cell-cell junctions. The Chloride intracellular Channel protein, CLIC2, translocated from actin-enriched plasma membrane bundles to cell-cell junctions upon activation of NK2 receptors. CLIC2, and one of its close paralogs, CLIC4, were further shown to respond with the same translocation pattern to muscarinic M3 and lysophosphatidic LPA receptors. This screen allowed us to identify potential actors in signaling pathways downstream of G protein-coupled receptors and could be scaled-up for high-content screening.
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Affiliation(s)
- Sandra Lecat
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France;
| | - Hans W D Matthes
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
| | - Rainer Pepperkok
- §European Molecular Biology Laboratory, Advanced Light Microscopy Facility, Meyerhofstr 1, 69117 Heidelberg, Germany
| | - Jeremy C Simpson
- ¶¶School of Biology and Environmental Science and UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jean-Luc Galzi
- From the ‡GPCRs, Pain and Inflammation Team, UMR7242, CNRS-University of Strasbourg, LabEx Medalis, 300 Bvd Sébastien Brant, 67412 Illkirch, France
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16
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Robinson DN. 14-3-3, an integrator of cell mechanics and cytokinesis. Small GTPases 2014; 1:165-169. [PMID: 21686271 DOI: 10.4161/sgtp.1.3.14432] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 12/07/2010] [Accepted: 12/09/2010] [Indexed: 11/19/2022] Open
Abstract
One of the goals of understanding cytokinesis is to uncover the molecular regulation of the cellular mechanical properties that drive cell shape change. Such regulatory pathways are likely to be used at multiple stages of a cell's life, but are highly featured during cell division. Recently, we demonstrated that 14-3-3 (encoded by a single gene in the social amoeba Dictyostelium discoideum) serves to integrate key cytoskeletal components-microtubules, Rac and myosin II-to control cell mechanics and cytokinesis. As 14-3-3 proteins are frequently altered in a variety of human tumors, we extend these observations to suggest possible additional roles for how 14-3-3 proteins may contribute to tumorigenesis.
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Affiliation(s)
- Douglas N Robinson
- Departments of Cell Biology; Pharmacology and Molecular Sciences; Johns Hopkins University School of Medicine; Department of Chemical and Biomolecular Engineering; Johns Hopkins University; Baltimore, MD USA
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17
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Padmakumar V, Masiuk KE, Luger D, Lee C, Coppola V, Tessarollo L, Hoover SB, Karavanova I, Buonanno A, Simpson RM, Yuspa SH. Detection of differential fetal and adult expression of chloride intracellular channel 4 (CLIC4) protein by analysis of a green fluorescent protein knock-in mouse line. BMC DEVELOPMENTAL BIOLOGY 2014; 14:24. [PMID: 24886590 PMCID: PMC4073518 DOI: 10.1186/1471-213x-14-24] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/13/2014] [Indexed: 01/17/2023]
Abstract
Background Chloride Intracellular Channel 4 (CLIC4) is one of seven members in the closely related CLIC protein family. CLIC4 is involved in multiple cellular processes including apoptosis, cellular differentiation, inflammation and endothelial tubulogenesis. Despite over a decade of research, no comprehensive in situ expression analysis of CLIC4 in a living organism has been reported. In order to fulfill this goal, we generated a knock-in mouse to express Green Fluorescent Protein (GFP) from the CLIC4 locus, thus substituting the GFP coding region for CLIC4. We used GFP protein expression to eliminate cross reaction with other CLIC family members. Results We analyzed CLIC4 expression during embryonic development and adult organs. During mid and late gestation, CLIC4 expression is modulated particularly in fetal brain, heart, thymus, liver and kidney as well as in developing brown adipose tissue and stratifying epidermis. In the adult mouse, CLIC4 is highly expressed globally in vascular endothelial cells as well as in liver, lung alveolar septae, pancreatic acini, spermatogonia, renal proximal tubules, cardiomyocytes and thymic epithelial cells. Neural expression included axonal tracks, olfactory bulb, Purkinje cell layer and dentate gyrus. Renal CLIC4 expression was most pronounced in proximal tubules, although altered renal function was not detected in the absence of CLIC4. Myeloid cells and B cells of the spleen are rich in CLIC4 expression as are CD4 and CD8 positive T cells. Conclusions In a comprehensive study detailing CLIC4 expression in situ in a mouse model that excludes cross reaction with other family members, we were able to document previously unreported expression for CLIC4 in developing fetus, particularly the brain. In addition, compartmentalized expression of CLIC4 in specific adult tissues and cells provides a focus to explore potential functions of this protein not addressed previously.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Stuart H Yuspa
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, Bethesda, MD, USA.
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18
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Edwards JC, Bruno J, Key P, Cheng YW. Absence of chloride intracellular channel 4 (CLIC4) predisposes to acute kidney injury but has minimal impact on recovery. BMC Nephrol 2014; 15:54. [PMID: 24708746 PMCID: PMC4234247 DOI: 10.1186/1471-2369-15-54] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 03/28/2014] [Indexed: 12/02/2022] Open
Abstract
Background CLIC4, a member of the CLIC family of proteins, was recently demonstrated to translocate to the nucleus in differentiating keratinocytes where it potentiates TGFβ-driven gene regulation. Since TGFβ signaling is known to play important roles in the fibrotic response to acute kidney injury, and since CLIC4 is abundantly expressed in kidney, we hypothesized that CLIC4 may play a role in the response to acute kidney injury. Methods Previously described Clic4 null mice were analyzed for the effect of absence of CLIC4 on growth, development and response to kidney injury. Kidney size, glomerular counts and density of peritubular capillaries of matched WT and Clic4 null mice were determined. Cohorts of WT and Clic4 null mice were subjected to the folic acid model of acute kidney injury. Extent of acute injury and long term functional recovery were assessed by plasma blood urea nitrogen (BUN); long term fibrosis/scarring was determined by histochemical assessment of kidney sections and by residual renal mass. Activation of the TGFβ signaling pathway was assessed by semi-quantitative western blots of phosphorylated SMADs 2 and 3. Results CLIC4 is abundantly expressed in the apical pole of renal proximal tubule cells, and in endothelial cells of glomerular and peritubular capillaries. CLIC4 null mice are small, have smaller kidneys with fewer glomeruli and less dense peritubular capillary networks, and have increased proteinuria. The Clic4 null mice show increased susceptibility to folic acid-induced acute kidney injury but no difference in recovery from acute injury, no nuclear redistribution of CLIC4 following injury, and no significant difference in activation of the TGFβ-signaling pathway as reflected in the level of phosphorylation of SMADs 2 and 3. Conclusions Absence of CLIC4 results in morphologic changes consistent with its known role in angiogenesis. These changes may be at least partially responsible for the increased susceptibility to acute kidney injury. However, the absence of CLIC4 has no significant impact on the extent of functional recovery or fibrosis following acute injury, indicating that CLIC4 does not play a major non-redundant role in the TGFβ signaling involved in response to acute kidney injury.
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Affiliation(s)
- John C Edwards
- Kidney Center and the Department of Internal Medicine, University of North Carolina, Chapel Hill NC, USA.
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19
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Argenzio E, Margadant C, Leyton-Puig D, Janssen H, Jalink K, Sonnenberg A, Moolenaar WH. CLIC4 regulates cell adhesion and β1 integrin trafficking. J Cell Sci 2014; 127:5189-203. [DOI: 10.1242/jcs.150623] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Chloride intracellular channel (CLIC) protein CLIC4 exists in both soluble and membrane-associated forms, and is implicated in diverse cellular processes, ranging from ion channel formation to intracellular membrane remodeling. CLIC4 is rapidly recruited to the plasma membrane by lysophosphatidic acid (LPA) and serum, suggesting a possible role for CLIC4 in exocytic-endocytic trafficking. However, the function and subcellular target(s) of CLIC4 remain elusive. Here we show that in HeLa and MDA-MB-231 cells, CLIC4 knockdown decreases cell-matrix adhesion, cell spreading and integrin signalling, while increasing cell motility. LPA stimulates the recruitment of CLIC4 to β1 integrins at the plasma membrane and in Rab35-positive endosomes. CLIC4 is required for both the internalization and the serum/LPA-induced recycling of β1 integrins, but not for EGF receptor trafficking. Furthermore, we show that CLIC4 suppresses Rab35 activity and antagonizes Rab35-dependent regulation of β1-integrin trafficking. Our results define CLIC4 as a regulator of Rab35 activity and serum/LPA-dependent integrin trafficking.
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20
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Viswanatha R, Wayt J, Ohouo PY, Smolka MB, Bretscher A. Interactome analysis reveals ezrin can adopt multiple conformational states. J Biol Chem 2013; 288:35437-51. [PMID: 24151071 DOI: 10.1074/jbc.m113.505669] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ezrin, a member of the ezrin-radixin-moesin family (ERM), is an essential regulator of the structure of microvilli on the apical aspect of epithelial cells. Ezrin provides a linkage between membrane-associated proteins and F-actin, oscillating between active/open and inactive/closed states, and is regulated in part by phosphorylation of a C-terminal threonine. In the open state, ezrin can bind a number of ligands, but in the closed state the ligand-binding sites are inaccessible. In vitro analysis has proposed that there may be a third hyperactivated form of ezrin. To gain a better understanding of ezrin, we conducted an unbiased proteomic analysis of ezrin-binding proteins in an epithelial cell line, Jeg-3. We refined our list of interactors by comparing the interactomes using quantitative mass spectrometry between wild-type ezrin, closed ezrin, open ezrin, and hyperactivated ezrin. The analysis reveals several novel interactors confirmed by their localization to microvilli, as well as a significant class of proteins that bind closed ezrin. Taken together, the data indicate that ezrin can exist in three different conformational states, and different ligands "perceive" ezrin conformational states differently.
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Affiliation(s)
- Raghuvir Viswanatha
- From the Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
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21
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Computational analysis of the soluble form of the intracellular chloride ion channel protein CLIC1. BIOMED RESEARCH INTERNATIONAL 2013; 2013:170586. [PMID: 24089665 PMCID: PMC3780514 DOI: 10.1155/2013/170586] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/26/2013] [Accepted: 06/27/2013] [Indexed: 11/18/2022]
Abstract
The chloride intracellular channel (CLIC) family of proteins has the remarkable property of maintaining both a soluble form and an integral membrane form acting as an ion channel. The soluble form is structurally related to the glutathione-S-transferase family, and CLIC can covalently bind glutathione via an active site cysteine. We report approximately 0.6 μs of molecular dynamics simulations, encompassing the three possible ligand-bound states of CLIC1, using the structure of GSH-bound human CLIC1. Noncovalently bound GSH was rapidly released from the protein, whereas the covalently ligand-bound protein remained close to the starting structure over 0.25 μs of simulation. In the unliganded state, conformational changes in the vicinity of the glutathione-binding site resulted in reduced reactivity of the active site thiol. Elastic network analysis indicated that the changes in the unliganded state are intrinsic to the protein architecture and likely represent functional transitions. Overall, our results are consistent with a model of CLIC function in which covalent binding of glutathione does not occur spontaneously but requires interaction with another protein to stabilise the GSH binding site and/or transfer of the ligand. The results do not indicate how CLIC1 undergoes a radical conformational change to form a transmembrane chloride channel but further elucidate the mechanism by which CLICs are redox controlled.
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22
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Tung JJ, Tattersall IW, Kitajewski J. Tips, stalks, tubes: notch-mediated cell fate determination and mechanisms of tubulogenesis during angiogenesis. Cold Spring Harb Perspect Med 2013; 2:a006601. [PMID: 22355796 DOI: 10.1101/cshperspect.a006601] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Angiogenesis is the process of developing vascular sprouts from existing blood vessels. Luminal endothelial cells convert into "tip" cells that contribute to the development of a multicellular stalk, which then undergoes lumen formation. In this review, we consider a variety of cellular and molecular pathways that mediate these transitions. We focus first on Notch signaling in cell fate determination as a mechanism to define tip and stalk cells. We next discuss the current models of lumen formation and describe new players in this process, such as chloride intracellular channel proteins. Finally, we consider the possible medical therapeutic benefits of understanding these processes and acknowledge potential obstacles in drug development.
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Affiliation(s)
- Jennifer J Tung
- Department of Obstetrics/Gynecology and Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, New York 10032, USA
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Abstract
Mammalian male fertility relies on complex inter- and intracellular signaling during spermatogenesis. Here we describe three alleles of the widely expressed A-kinase anchoring protein 9 (Akap9) gene, all of which cause gametogenic failure and infertility in the absence of marked somatic phenotypes. Akap9 disruption does not affect spindle nucleation or progression of prophase I of meiosis but does inhibit maturation of Sertoli cells, which continue to express the immaturity markers anti-Mullerian hormone and thyroid hormone receptor alpha in adults and fail to express the maturation marker p27(Kip1). Furthermore, gap and tight junctions essential for blood-testis barrier (BTB) organization are disrupted. Connexin43 (Cx43) and zona occludens-1 are improperly localized in Akap9 mutant testes, and Cx43 fails to compartmentalize germ cells near the BTB. These results identify and support a novel reproductive tissue-specific role for Akap9 in the coordinated regulation of Sertoli cells in the testis.
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Xu Y, Kang J, Yuan Z, Li H, Su J, Li Y, Kong X, Zhang H, Wang W, Sun L. Suppression of CLIC4/mtCLIC enhances hydrogen peroxide-induced apoptosis in C6 glioma cells. Oncol Rep 2013; 29:1483-91. [PMID: 23380911 DOI: 10.3892/or.2013.2265] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 11/02/2012] [Indexed: 11/06/2022] Open
Abstract
CLIC4/mtCLIC (referred to here as CLIC4) is one of the seven-member family of chloride intracellular channels (CLIC). CLIC4 localizes to the mitochondria, nucleus, cytoplasm and other organellular compartments and participates in the apoptotic response to stress. However, the role of CLIC4 in oxidative stress and apoptosis is not well understood. In this study, we showed the important role of CLIC4 in apoptosis of C6 glioma cells induced by hydrogen peroxide (H2O2). Our results showed that CLIC4 protein expression was upregulated following H2O2-induced C6 cell apoptosis. The upregulation of CLIC4 protein expression was paralleled with an increased Bax/Bcl-2 ratio, cytochrome c and cleaved caspase-3 protein expression upon H2O2-induced C6 cell apoptosis. Suppression of CLIC4 expression by RNA interference enhanced cell apoptosis, but the ratio of Bax/Bcl-2 was not involved in this process. Dissipation of mitochondrial membrane potential and nuclear translocation of CLIC4 were involved in the activation of apoptosis induced by H2O2. Our data indicate that CLIC4 protein may be a key element in the apoptotic response to oxidative stress.
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Affiliation(s)
- Ye Xu
- Department of Pathophysiology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, PR China
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Zhong J, Kong X, Zhang H, Yu C, Xu Y, Kang J, Yu H, Yi H, Yang X, Sun L. Inhibition of CLIC4 enhances autophagy and triggers mitochondrial and ER stress-induced apoptosis in human glioma U251 cells under starvation. PLoS One 2012; 7:e39378. [PMID: 22761775 PMCID: PMC3382619 DOI: 10.1371/journal.pone.0039378] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/21/2012] [Indexed: 12/19/2022] Open
Abstract
CLIC4/mtCLIC, a chloride intracellular channel protein, localizes to mitochondria, endoplasmic reticulum (ER), nucleus and cytoplasm, and participates in the apoptotic response to stress. Apoptosis and autophagy, the main types of the programmed cell death, seem interconnected under certain stress conditions. However, the role of CLIC4 in autophagy regulation has yet to be determined. In this study, we demonstrate upregulation and nuclear translocation of the CLIC4 protein following starvation in U251 cells. CLIC4 siRNA transfection enhanced autophagy with increased LC3-II protein and puncta accumulation in U251 cells under starvation conditions. In that condition, the interaction of the 14-3-3 epsilon isoform with CLIC4 was abolished and resulted in Beclin 1 overactivation, which further activated autophagy. Moreover, inhibiting the expression of CLIC4 triggered both mitochondrial apoptosis involved in Bax/Bcl-2 and cytochrome c release under starvation and endoplasmic reticulum stress-induced apoptosis with CHOP and caspase-4 upregulation. These results demonstrate that CLIC4 nuclear translocation is an integral part of the cellular response to starvation. Inhibiting the expression of CLIC4 enhances autophagy and contributes to mitochondrial and ER stress-induced apoptosis under starvation.
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Affiliation(s)
- Jiateng Zhong
- Department of Pathophysiology, Norman Bethune College of Medicine, Jilin University, Changchun, Jilin, China
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Suh KS, Malik M, Shukla A, Ryscavage A, Wright L, Jividen K, Crutchley JM, Dumont RA, Fernandez-Salas E, Webster JD, Simpson RM, Yuspa SH. CLIC4 is a tumor suppressor for cutaneous squamous cell cancer. Carcinogenesis 2012; 33:986-95. [PMID: 22387366 DOI: 10.1093/carcin/bgs115] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Chloride intracellular channel (CLIC) 4 is a member of a redox-regulated, metamorphic multifunctional protein family, first characterized as intracellular chloride channels. Current knowledge indicates that CLICs participate in signaling, cytoskeleton integrity and differentiation functions of multiple tissues. In metabolically stressed skin keratinocytes, cytoplasmic CLIC4 is S-nitrosylated and translocates to the nucleus where it enhances transforming growth factor-β (TGF-β) signaling by protecting phospho-Smad 2 and 3 from dephosphorylation. CLIC4 expression is diminished in multiple human epithelial cancers, and the protein is excluded from the nucleus. We now show that CLIC4 expression is reduced in chemically induced mouse skin papillomas, mouse and human squamous carcinomas and squamous cancer cell lines, and the protein is excluded from the nucleus. The extent of reduction in CLIC4 coincides with progression of squamous tumors from benign to malignant. Inhibiting antioxidant defense in tumor cells increases S-nitrosylation and nuclear translocation of CLIC4. Adenoviral-mediated reconstitution of nuclear CLIC4 in squamous cancer cells enhances TGF-β-dependent transcriptional activity and inhibits growth. Adenoviral targeting of CLIC4 to the nucleus of tumor cells in orthografts inhibits tumor growth, whereas elevation of CLIC4 in transgenic epidermis reduces de novo chemically induced skin tumor formation. In parallel, overexpression of exogenous CLIC4 in squamous tumor orthografts suppresses tumor growth and enhances TGF-β signaling. These results indicate that CLIC4 suppresses the growth of squamous cancers, that reduced CLIC4 expression and nuclear residence detected in cancer cells is associated with the altered redox state of tumor cells and the absence of detectable nuclear CLIC4 in cancers contributes to TGF-β resistance and enhances tumor development.
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Affiliation(s)
- K Stephen Suh
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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Mattaloni SM, Kolobova E, Favre C, Marinelli RA, Goldenring JR, Larocca MC. AKAP350 Is involved in the development of apical "canalicular" structures in hepatic cells HepG2. J Cell Physiol 2011; 227:160-71. [PMID: 21374596 DOI: 10.1002/jcp.22713] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Hepatocytes are epithelial cells whose apical poles constitute the bile canaliculi. The establishment and maintenance of canalicular poles is a finely regulated process that dictates the efficiency of primary bile secretion. Protein kinase A (PKA) modulates this process at different levels. AKAP350 is an A-kinase anchoring protein that scaffolds protein complexes involved in modulating the dynamic structures of the Golgi apparatus and microtubule cytoskeleton, facilitating microtubule nucleation at this organelle. In this study, we evaluated whether AKAP350 is involved in the development of bile canaliculi-like structures in hepatocyte derived HepG2 cells. We found that AKAP350 recruits PKA to the centrosomes and Golgi apparatus in HepG2 cells. De-localization of AKAP350 from these organelles led to reduced apical cell polarization. A decrease in AKAP350 expression inhibited the formation of canalicular structures and impaired F-actin organization at canalicular poles. Furthermore, loss of AKAP350 expression led to diminished polarized expression of the p-glycoprotein (MDR1/ABCB1) at the apical "canalicular" membrane. AKAP350 knock down effects on canalicular structures formation and actin organization could be mimicked by inhibition of Golgi microtubule nucleation by depletion of CLIP associated proteins (CLASPs). Our data reveal that AKAP350 participates in mechanisms which determine the development of canalicular structures as well as accurate canalicular expression of distinct proteins and actin organization, and provide evidence on the involvement of Golgi microtubule nucleation in hepatocyte apical polarization.
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Affiliation(s)
- Stella M Mattaloni
- Instituto de Fisiología Experimental, Consejo de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Goodchild SC, Angstmann CN, Breit SN, Curmi PMG, Brown LJ. Transmembrane extension and oligomerization of the CLIC1 chloride intracellular channel protein upon membrane interaction. Biochemistry 2011; 50:10887-97. [PMID: 22082111 DOI: 10.1021/bi2012564] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chloride intracellular channel proteins (CLICs) differ from most ion channels as they can exist in both soluble and integral membrane forms. The CLICs are expressed as soluble proteins but can reversibly autoinsert into the membrane to form active ion channels. For CLIC1, the interaction with the lipid bilayer is enhanced under oxidative conditions. At present, little evidence is available characterizing the structure of the putative oligomeric CLIC integral membrane form. Previously, fluorescence resonance energy transfer (FRET) was used to monitor and model the conformational transition within CLIC1 as it interacts with the membrane bilayer. These results revealed a large-scale unfolding between the C- and N-domains of CLIC1 as it interacts with the membrane. In the present study, FRET was used to probe lipid-induced structural changes arising in the vicinity of the putative transmembrane region of CLIC1 (residues 24-46) under oxidative conditions. Intramolecular FRET distances are consistent with the model in which the N-terminal domain inserts into the bilayer as an extended α-helix. Further, intermolecular FRET was performed between fluorescently labeled CLIC1 monomers within membranes. The intermolecular FRET shows that CLIC1 forms oligomers upon oxidation in the presence of the membranes. Fitting the data to symmetric oligomer models of the CLIC1 transmembrane form indicates that the structure is large and most consistent with a model comprising approximately six to eight subunits.
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Affiliation(s)
- Sophia C Goodchild
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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29
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Dulhunty AF, Hewawasam R, Liu D, Casarotto MG, Board PG. Regulation of the cardiac muscle ryanodine receptor by glutathione transferases. Drug Metab Rev 2011; 43:236-52. [DOI: 10.3109/03602532.2010.549134] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tung JJ, Kitajewski J. Chloride intracellular channel 1 functions in endothelial cell growth and migration. JOURNAL OF ANGIOGENESIS RESEARCH 2010; 2:23. [PMID: 21040583 PMCID: PMC2993651 DOI: 10.1186/2040-2384-2-23] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 11/01/2010] [Indexed: 12/29/2022]
Abstract
Background Little is known about the role of CLIC1 in endothelium. These studies investigate CLIC1 as a regulator of angiogenesis by in vitro techniques that mimic individual steps in the angiogenic process. Methods Using shRNA against clic1, we determined the role of CLIC1 in primary human endothelial cell behavior. Results Here, we report that reduced CLIC1 expression caused a reduction in endothelial migration, cell growth, branching morphogenesis, capillary-like network formation, and capillary-like sprouting. FACS analysis showed that CLIC1 plays a role in regulating the cell surface expression of various integrins that function in angiogenesis including β1 and α3 subunits, as well as αVβ3 and αVβ5. Conclusions Together, these results indicate that CLIC1 is required for multiple steps of in vitro angiogenesis and plays a role in regulating integrin cell surface expression.
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Affiliation(s)
- Jennifer J Tung
- Department of Obstetrics/Gynecology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, 1130 St, Nicholas Ave, 926, New York, NY 10032, USA.
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AKAP9 regulation of microtubule dynamics promotes Epac1-induced endothelial barrier properties. Blood 2010; 117:708-18. [PMID: 20952690 DOI: 10.1182/blood-2010-02-268870] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Adhesive forces at endothelial cell-cell borders maintain vascular integrity. cAMP enhances barrier properties and controls cellular processes through protein kinase A bound to A-kinase anchoring proteins (AKAPs). It also activates exchange protein directly activated by cAMP (Epac1), an exchange factor for Ras-related protein 1 (Rap1) GTPases that promotes cadherin- and integrin-mediated adhesion through effects on the actin cytoskeleton. We demonstrate that AKAP9 facilitates the microtubule polymerization rate in endothelial cells, interacts with Epac1, and is required for Epac1-stimulated microtubule growth. AKAP9 is not required for maintaining barrier properties under steady-state conditions. Rather, it is essential when the cell is challenged to make new adhesive contacts, as is the case when Epac activation enhances barrier function through a mechanism that, surprisingly, requires integrin adhesion at cell-cell contacts. In the present study, defects in Epac-induced responses in AKAP9-silenced cells were evident despite an intact Epac-induced increase in Rap activation, cortical actin, and vascular endothelial-cadherin adhesion. We describe a pathway that integrates Epac-mediated signals with AKAP9-dependent microtubule dynamics to coordinate integrins at lateral borders.
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Goodchild SC, Howell MW, Littler DR, Mandyam RA, Sale KL, Mazzanti M, Breit SN, Curmi PMG, Brown LJ. Metamorphic response of the CLIC1 chloride intracellular ion channel protein upon membrane interaction. Biochemistry 2010; 49:5278-89. [PMID: 20507120 DOI: 10.1021/bi100111c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A striking feature of the CLIC (chloride intracellular channel) protein family is the ability of its members to convert between a soluble state and an integral membrane channel form. Direct evidence of the structural transition required for the CLIC protein to autonomously insert into the membrane is lacking, largely because of the challenge of probing the conformation of the membrane-bound protein. However, insights into the CLIC transmembrane form can be gained by biophysical methods such as fluorescence resonance energy transfer (FRET) spectroscopy. This approach was used to measure distances from tryptophan 35, located within the CLIC1 putative N-domain transmembrane region, to three native cysteine residues within the C-terminal domain. These distances were computed both in aqueous solution and upon the addition of membrane vesicles. The FRET distances were used as constraints for modeling of a structure for the CLIC1 integral membrane form. The data are suggestive of a large conformational unfolding occurring between the N- and C-domains of CLIC1 upon interaction with the membrane. Consistent with previous findings, the N-terminal domain of CLIC1 is likely to insert into the lipid bilayer, while the C-domain remains in solution on the extravesicular side of the membrane.
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Affiliation(s)
- Sophia C Goodchild
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Chuang JZ, Chou SY, Sung CH. Chloride intracellular channel 4 is critical for the epithelial morphogenesis of RPE cells and retinal attachment. Mol Biol Cell 2010; 21:3017-28. [PMID: 20610659 PMCID: PMC2929995 DOI: 10.1091/mbc.e09-10-0907] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A plasmid-based transfection method was used to cell-autonomously silence chloride intracellular channel 4 (CLIC4) in RPE in situ. These results show CLIC4 is critical for epithelial morphogenesis and retinal attachment. Novel candidate targets for retinal detachment therapy have also been identified. Retinal detachment is a sight-threatening condition. The molecular mechanism underlying the adhesion between the RPE and photoreceptors is poorly understood because the intimate interactions between these two cell types are impossible to model and study in vitro. In this article, we show that chloride intracellular channel 4 (CLIC4) is enriched at apical RPE microvilli, which are interdigitated with the photoreceptor outer segment. We used a novel plasmid-based transfection method to cell-autonomously suppress CLIC4 in RPE in situ. CLIC4 silenced RPE cells exhibited a significant loss of apical microvilli and basal infoldings, reduced retinal adhesion, and epithelial-mesenchymal transition. Ectopically expressing ezrin failed to rescue the morphological changes exerted by CLIC4 silencing. Neural retinas adjacent to the CLIC4-suppressed RPE cells display severe dysplasia. Finally, a high level of aquaporin 1 unexpectedly appeared at the apical surfaces of CLIC4-suppressed RPE cells, together with a concomitant loss of basal surface expression of monocarboxylate transporter MCT3. Our results suggested that CLIC4 plays an important role in RPE-photoreceptor adhesion, perhaps by modulating the activity of cell surface channels/transporters. We propose that these changes may be attributable to subretinal fluid accumulation in our novel retinal detachment animal model.
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Affiliation(s)
- Jen-Zen Chuang
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10021, USA
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Wegner B, Al-Momany A, Kulak SC, Kozlowski K, Obeidat M, Jahroudi N, Paes J, Berryman M, Ballermann BJ. CLIC5A, a component of the ezrin-podocalyxin complex in glomeruli, is a determinant of podocyte integrity. Am J Physiol Renal Physiol 2010; 298:F1492-503. [PMID: 20335315 DOI: 10.1152/ajprenal.00030.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The chloride intracellular channel 5A (CLIC5A) protein, one of two isoforms produced by the CLIC5 gene, was isolated originally as part of a cytoskeletal protein complex containing ezrin from placental microvilli. Whether CLIC5A functions as a bona fide ion channel is controversial. We reported previously that a CLIC5 transcript is enriched approximately 800-fold in human renal glomeruli relative to most other tissues. Therefore, this study sought to explore CLIC5 expression and function in glomeruli. RT-PCR and Western blots show that CLIC5A is the predominant CLIC5 isoform expressed in glomeruli. Confocal immunofluorescence and immunogold electron microscopy reveal high levels of CLIC5A protein in glomerular endothelial cells and podocytes. In podocytes, CLIC5A localizes to the apical plasma membrane of foot processes, similar to the known distribution of podocalyxin and ezrin. Ezrin and podocalyxin colocalize with CLIC5A in glomeruli, and podocalyxin coimmunoprecipitates with CLIC5A from glomerular lysates. In glomeruli of jitterbug (jbg/jbg) mice, which lack the CLIC5A protein, ezrin and phospho-ERM levels in podocytes are markedly lower than in wild-type mice. Transmission electron microscopy reveals patchy broadening and effacement of podocyte foot processes as well as vacuolization of glomerular endothelial cells. These ultrastructural changes are associated with microalbuminuria at baseline and increased susceptibility to adriamycin-induced glomerular injury compared with wild-type mice. Together, the data suggest that CLIC5A is required for the development and/or maintenance of the proper glomerular endothelial cell and podocyte architecture. We postulate that the interaction between podocalyxin and subjacent filamentous actin, which requires ezrin, is compromised in podocytes of CLIC5A-deficient mice, leading to dysfunction under unfavorable genetic or environmental conditions.
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Affiliation(s)
- Binytha Wegner
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Two decades with dimorphic Chloride Intracellular Channels (CLICs). FEBS Lett 2010; 584:2112-21. [DOI: 10.1016/j.febslet.2010.03.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 01/11/2023]
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Chloride channels of intracellular membranes. FEBS Lett 2010; 584:2102-11. [PMID: 20100480 DOI: 10.1016/j.febslet.2010.01.037] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 01/13/2010] [Accepted: 01/19/2010] [Indexed: 11/20/2022]
Abstract
Proteins implicated as intracellular chloride channels include the intracellular ClC proteins, the bestrophins, the cystic fibrosis transmembrane conductance regulator, the CLICs, and the recently described Golgi pH regulator. This paper examines current hypotheses regarding roles of intracellular chloride channels and reviews the evidence supporting a role in intracellular chloride transport for each of these proteins.
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Littler DR, Harrop SJ, Goodchild SC, Phang JM, Mynott AV, Jiang L, Valenzuela SM, Mazzanti M, Brown LJ, Breit SN, Curmi PMG. The enigma of the CLIC proteins: Ion channels, redox proteins, enzymes, scaffolding proteins? FEBS Lett 2010; 584:2093-101. [PMID: 20085760 DOI: 10.1016/j.febslet.2010.01.027] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 12/13/2022]
Abstract
Chloride intracellular channel proteins (CLICs) are distinct from most ion channels in that they have both soluble and integral membrane forms. CLICs are highly conserved in chordates, with six vertebrate paralogues. CLIC-like proteins are found in other metazoans. CLICs form channels in artificial bilayers in a process favoured by oxidising conditions and low pH. They are structurally plastic, with CLIC1 adopting two distinct soluble conformations. Phylogenetic and structural data indicate that CLICs are likely to have enzymatic function. The physiological role of CLICs appears to be maintenance of intracellular membranes, which is associated with tubulogenesis but may involve other substructures.
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Affiliation(s)
- Dene R Littler
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
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Yang JY, Jung JY, Cho SW, Choi HJ, Kim SW, Kim SY, Kim HJ, Jang CH, Lee MG, Han J, Shin CS. Chloride intracellular channel 1 regulates osteoblast differentiation. Bone 2009; 45:1175-85. [PMID: 19703605 DOI: 10.1016/j.bone.2009.08.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 08/14/2009] [Accepted: 08/17/2009] [Indexed: 12/15/2022]
Abstract
We have identified chloride intracellular channel 1 (CLIC1) through proteomic approach, which was increased in response to canonical wnt signaling while being almost shut-off by adipogenic treatment in mouse mesenchymal C3H10T1/2 cells. We found that CLIC1 was expressed in mouse (MC3T3-E1), rat (ROS 17/2.8 and UMR-106) or human (MG63 and SaOS2) osteoblastic cell lines as well as primary culture of mouse calvarial cells by RT-PCR or Western blot analysis. The expression level of CLIC1 is increased upon treatment of osteogenic medium, whereas it almost disappeared in adipogenic condition, confirming the proteomic data. The expression of CLIC1 was localized mainly in nuclear membrane and vesiculo-cytoplasmic, the latter of which was colocalized with mitochondria. Retroviral overexpression of CLIC1 did not increase whole-cell current but induces hyperpolarization of mitochondrial membrane potential estimated using the fluorescent dye TMRE. Moreover, overexpression of CLIC1 resulted in increase in osteoblastic differentiation of C3H10T1/2 cells as measured by ALP activities or osteoblastic gene expression (osterix, ALP and osteocalcin), although it did not result in induction of Runx2 transcription activities at mouse osteocalcin (OG2) promoter. Finally, in vitro knock-down of CLIC1 using stable siRNA CLIC1 significantly suppressed osteoblastic differentiation. Taken together, these results suggest that CLIC1 may play a role in the regulation of osteoblastic differentiation from mesenchymal progenitors, although its physiologic role in osteoblasts remains to be determined.
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Affiliation(s)
- Jae-Yeon Yang
- Department of Internal Medicine, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-Gu, Seoul 110-744, Korea
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Ponsioen B, van Zeijl L, Langeslag M, Berryman M, Littler D, Jalink K, Moolenaar WH. Spatiotemporal regulation of chloride intracellular channel protein CLIC4 by RhoA. Mol Biol Cell 2009; 20:4664-72. [PMID: 19776349 DOI: 10.1091/mbc.e09-06-0529] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Chloride intracellular channel (CLIC) 4 is a soluble protein structurally related to omega-type glutathione-S-transferases (GSTs) and implicated in various biological processes, ranging from chloride channel formation to vascular tubulogenesis. However, its function(s) and regulation remain unclear. Here, we show that cytosolic CLIC4 undergoes rapid but transient translocation to discrete domains at the plasma membrane upon stimulation of G(13)-coupled, RhoA-activating receptors, such as those for lysophosphatidic acid, thrombin, and sphingosine-1-phosphate. CLIC4 recruitment is strictly dependent on Galpha(13)-mediated RhoA activation and F-actin integrity, but not on Rho kinase activity; it is constitutively induced upon enforced RhoA-GTP accumulation. Membrane-targeted CLIC4 does not seem to enter the plasma membrane or modulate transmembrane chloride currents. Mutational analysis reveals that CLIC4 translocation depends on at least six conserved residues, including reactive Cys35, whose equivalents are critical for the enzymatic function of GSTs. We conclude that CLIC4 is regulated by RhoA to be targeted to the plasma membrane, where it may function not as an inducible chloride channel but rather by displaying Cys-dependent transferase activity toward a yet unknown substrate.
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Affiliation(s)
- Bas Ponsioen
- Division of Cell Biology and Center for Biomedical Genetics, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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Spiekerkoetter E, Guignabert C, de Jesus Perez V, Alastalo TP, Powers JM, Wang L, Lawrie A, Ambartsumian N, Schmidt AM, Berryman M, Ashley RH, Rabinovitch M. S100A4 and bone morphogenetic protein-2 codependently induce vascular smooth muscle cell migration via phospho-extracellular signal-regulated kinase and chloride intracellular channel 4. Circ Res 2009; 105:639-47, 13 p following 647. [PMID: 19713532 DOI: 10.1161/circresaha.109.205120] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
RATIONALE S100A4/Mts1 is implicated in motility of human pulmonary artery smooth muscle cells (hPASMCs), through an interaction with the RAGE (receptor for advanced glycation end products). OBJECTIVE We hypothesized that S100A4/Mts1-mediated hPASMC motility might be enhanced by loss of function of bone morphogenetic protein (BMP) receptor (BMPR)II, observed in pulmonary arterial hypertension. METHODS AND RESULTS Both S100A4/Mts1 (500 ng/mL) and BMP-2 (10 ng/mL) induce migration of hPASMCs in a novel codependent manner, in that the response to either ligand is lost with anti-RAGE or BMPRII short interference (si)RNA. Phosphorylation of extracellular signal-regulated kinase is induced by both ligands and is required for motility by inducing matrix metalloproteinase 2 activity, but phospho-extracellular signal-regulated kinase 1/2 is blocked by anti-RAGE and not by BMPRII short interference RNA. In contrast, BMPRII short interference RNA, but not anti-RAGE, reduces expression of intracellular chloride channel (CLIC)4, a scaffolding molecule necessary for motility in response to S100A4/Mts1 or BMP-2. Reduced CLIC4 expression does not interfere with S100A4/Mts1 internalization or its interaction with myosin heavy chain IIA, but does alter alignment of myosin heavy chain IIA and actin filaments creating the appearance of vacuoles. This abnormality is associated with reduced peripheral distribution and/or delayed activation of RhoA and Rac1, small GTPases required for retraction and extension of lamellipodia in motile cells. CONCLUSIONS Our studies demonstrate how a single ligand (BMP-2 or S100A4/Mts1) can recruit multiple cell surface receptors to relay signals that coordinate events culminating in a functional response, ie, cell motility. We speculate that this carefully controlled process limits signals from multiple ligands, but could be subverted in disease.
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Affiliation(s)
- Edda Spiekerkoetter
- Department of Pediatrics, Stanford University School of Medicine, Stanford, Calif 94305-5162, USA
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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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Tung JJ, Hobert O, Berryman M, Kitajewski J. Chloride intracellular channel 4 is involved in endothelial proliferation and morphogenesis in vitro. Angiogenesis 2009; 12:209-20. [PMID: 19247789 DOI: 10.1007/s10456-009-9139-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 02/12/2009] [Indexed: 11/24/2022]
Abstract
New capillaries are formed through angiogenesis and an integral step in this process is endothelial tubulogenesis. The molecular mechanisms driving tube formation during angiogenesis are not yet delineated. Recently, the chloride intracellular channel 4 (CLIC4)-orthologue EXC-4 was found to be necessary for proper development and maintenance of the Caenorhabditis elegans excretory canal, implicating CLIC4 as a regulator of tubulogenesis. Here, we studied the role of CLIC4 in angiogenesis and endothelial tubulogenesis. We report the effects of inhibiting or inducing CLIC4 expression on distinct aspects of endothelial cell behavior in vitro. Our experiments utilized RNA interference to establish cultured human endothelial cell lines with significant reduction of CLIC4 expression, and a CLIC4-expressing lentiviral plasmid was used to establish CLIC4 overexpression in endothelial cells. We observed no effect on cell migration and a modest effect on cell survival. Reduced CLIC4 expression decreased cell proliferation, capillary network formation, capillary-like sprouting, and lumen formation. This suggests that normal endogenous CLIC4 expression is required for angiogenesis and tubulogenesis. Accordingly, increased CLIC4 expression promoted proliferation, network formation, capillary-like sprouting, and lumen formation. We conclude that CLIC4 functions to promote endothelial cell proliferation and to regulate endothelial morphogenesis, and is thus involved in multiple steps of in vitro angiogenesis.
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Affiliation(s)
- Jennifer J Tung
- Department of Obstetrics/Gynecology and Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032, USA
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Jalilian C, Gallant EM, Board PG, Dulhunty AF. Redox potential and the response of cardiac ryanodine receptors to CLIC-2, a member of the glutathione S-transferase structural family. Antioxid Redox Signal 2008; 10:1675-86. [PMID: 18522493 DOI: 10.1089/ars.2007.1994] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The type 2 chloride intracellular channel, CLIC-2, is a member of the glutathione S-transferase structural family and a suppressor of cardiac ryanodine receptor (RyR2) Ca2+ channels located in the membrane of the sarcoplasmic reticulum (SR). Modulators of RyR2 activity can alter cardiac contraction. Since both CLIC-2 and RyR2 are modified by redox reactions, we speculated that the action of CLIC-2 on RyR2 may depend on redox potential. We used a GSH:GSSG buffer system to produce mild changes in redox potential to influence redox sensors in RyR2 and CLIC-2. RyR2 activity was modified only when both luminal and cytoplasmic solutions contained the GSH:GSSG buffer and the effects were reversed by removing the buffer from one of the solutions. Channel activity increased with an oxidizing redox potential and decreased when the potential was more reducing. Addition of cytoplasmic CLIC-2 inhibited RyR2 with oxidizing redox potentials, but activated RyR2 under reducing conditions. The results suggested that both RyR2 and CLIC-2 contain redox sensors. Since cardiac ischemia involves a destructive Ca2+ overload that is partly due to oxidation-induced increase in RyR2 activity, we speculate that the properties of CLIC-2 place it in an ideal position to limit ischemia-induced cellular damage in cardiac muscle.
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Affiliation(s)
- Chris Jalilian
- Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, ACT, Australia
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Park YD, Park D, Bhak J, Yang JM. Proteomic approaches to the analysis of atopic dermatitis and new insights from interactomics. Proteomics Clin Appl 2008; 2:290-300. [DOI: 10.1002/prca.200780063] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rajasekaran SA, Beyenbach KW, Rajasekaran AK. Interactions of tight junctions with membrane channels and transporters. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:757-69. [PMID: 18086552 DOI: 10.1016/j.bbamem.2007.11.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 11/02/2007] [Accepted: 11/09/2007] [Indexed: 12/22/2022]
Abstract
Tight junctions are unique organelles in epithelial cells. They are localized to the apico-lateral region and essential for the epithelial cell transport functions. The paracellular transport process that occurs via tight junctions is extensively studied and is intricately regulated by various extracellular and intracellular signals. Fine regulation of this transport pathway is crucial for normal epithelial cell functions. Among factors that control tight junction permeability are ions and their transporters. However, this area of research is still in its infancy and much more needs to be learned about how these molecules regulate tight junction structure and functions. In this review we have attempted to compile literature on ion transporters and channels involved in the regulation of tight junctions.
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Affiliation(s)
- Sigrid A Rajasekaran
- The Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA 90095, USA
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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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Suh KS, Malik M, Shukla A, Yuspa SH. CLIC4, skin homeostasis and cutaneous cancer: surprising connections. Mol Carcinog 2007; 46:599-604. [PMID: 17443730 DOI: 10.1002/mc.20324] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chloride intracellular channel 4 (CLIC4) is a putative chloride channel for intracellular organelles. CLIC4 has biological activities in addition to or because of its channel activity. In keratinocytes, CLIC4 resides in the mitochondria and cytoplasm, and CLIC4 gene expression is regulated by p53, TNF-alpha, and c-Myc. Cytoplasmic CLIC4 translocates to the nucleus in response to cellular stress conditions including DNA damage, metabolic inhibition, senescence, and exposure to certain trophic factors such as TNF-alpha and LPS. Nuclear translocation is associated with growth arrest or apoptosis, depending on the level of expression. In the nucleus CLIC4 interacts with several nuclear proteins as demonstrated by yeast two-hybrid screening and co-immunoprecipitation. Nuclear CLIC4 appears to act on the TGF-beta pathway, and TGF-beta also causes CLIC4 nuclear translocation. In human and mouse cancer cell lines, CLIC4 levels are reduced, and CLIC4 is excluded from the nucleus. CLIC4 soluble or membrane-inserted status is dependent on redox state, and redox alterations in cancer cells could underly the defect in nuclear translocation. CLIC4 is reduced and excluded from the nucleus of many human epithelial neoplasms. Paradoxically, CLIC4 is reciprocally upregulated in tumor stroma in conjunction with the expression of alpha-smooth muscle actin in the fibroblast to myofibroblast transition. Overexpression of CLIC4 in cancer cells inhibits tumor growth in vivo. Conversely, overexpression of CLIC4 in tumor stromal cells stimulates tumor growth in vivo. Thus, CLIC4 participates in normal and pathological processes and may serve as a useful target for therapies in disturbances of homeostasis and neoplastic transformation.
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Affiliation(s)
- Kwang S Suh
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research National Cancer Institute, Bethesda, Maryland 20892, USA
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Suh KS, Mutoh M, Mutoh T, Li L, Ryscavage A, Crutchley JM, Dumont RA, Cheng C, Yuspa SH. CLIC4 mediates and is required for Ca2+-induced keratinocyte differentiation. J Cell Sci 2007; 120:2631-40. [PMID: 17636002 DOI: 10.1242/jcs.002741] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Keratinocyte differentiation requires integrating signaling among intracellular ionic changes, kinase cascades, sequential gene expression, cell cycle arrest, and programmed cell death. We now show that Cl(-) intracellular channel 4 (CLIC4) expression is increased in both mouse and human keratinocytes undergoing differentiation induced by Ca(2+), serum and the protein kinase C (PKC)-activator, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Elevation of CLIC4 is associated with signaling by PKCdelta, and knockdown of CLIC4 protein by antisense or shRNA prevents Ca(2+)-induced keratin 1, keratin 10 and filaggrin expression and cell cycle arrest in differentiating keratinocytes. CLIC4 is cytoplasmic in actively proliferating keratinocytes in vitro, but the cytoplasmic CLIC4 translocates to the nucleus in keratinocytes undergoing growth arrest by differentiation, senescence or transforming growth factor beta (TGFbeta) treatment. Targeting CLIC4 to the nucleus of keratinocytes via adenoviral transduction increases nuclear Cl(-) content and enhances expression of differentiation markers in the absence of elevated Ca(2+). In vivo, CLIC4 is localized to the epidermis in mouse and human skin, where it is predominantly nuclear in quiescent cells. These results suggest that CLIC4 participates in epidermal homeostasis through both alterations in the level of expression and subcellular localization. Nuclear CLIC4, possibly by altering the Cl(-) and pH of the nucleus, contributes to cell cycle arrest and the specific gene expression program associated with keratinocyte terminal differentiation.
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Affiliation(s)
- Kwang S Suh
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
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