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Hey G, Rao R, Carter A, Reddy A, Valle D, Patel A, Patel D, Lucke-Wold B, Pomeranz Krummel D, Sengupta S. Ligand-Gated Ion Channels: Prognostic and Therapeutic Implications for Gliomas. J Pers Med 2023; 13:jpm13050853. [PMID: 37241023 DOI: 10.3390/jpm13050853] [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: 04/20/2023] [Revised: 05/05/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023] Open
Abstract
Gliomas are common primary brain malignancies that remain difficult to treat due to their overall aggressiveness and heterogeneity. Although a variety of therapeutic strategies have been employed for the treatment of gliomas, there is increasing evidence that suggests ligand-gated ion channels (LGICs) can serve as a valuable biomarker and diagnostic tool in the pathogenesis of gliomas. Various LGICs, including P2X, SYT16, and PANX2, have the potential to become altered in the pathogenesis of glioma, which can disrupt the homeostatic activity of neurons, microglia, and astrocytes, further exacerbating the symptoms and progression of glioma. Consequently, LGICs, including purinoceptors, glutamate-gated receptors, and Cys-loop receptors, have been targeted in clinical trials for their potential therapeutic benefit in the diagnosis and treatment of gliomas. In this review, we discuss the role of LGICs in the pathogenesis of glioma, including genetic factors and the effect of altered LGIC activity on the biological functioning of neuronal cells. Additionally, we discuss current and emerging investigations regarding the use of LGICs as a clinical target and potential therapeutic for gliomas.
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Affiliation(s)
- Grace Hey
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Rohan Rao
- College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Ashley Carter
- Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Akshay Reddy
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Daisy Valle
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Anjali Patel
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Drashti Patel
- College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Brandon Lucke-Wold
- Department of Neurosurgery, University of Florida, Gainesville, FL 23608, USA
| | - Daniel Pomeranz Krummel
- Department of Neurology & Rehabilitation Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Soma Sengupta
- Department of Neurology & Rehabilitation Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
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Cryo-EM structure of human heptameric pannexin 2 channel. Nat Commun 2023; 14:1118. [PMID: 36869038 PMCID: PMC9984531 DOI: 10.1038/s41467-023-36861-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 02/19/2023] [Indexed: 03/05/2023] Open
Abstract
Pannexin 2 (Panx2) is a large-pore ATP-permeable channel with critical roles in various physiological processes, such as the inflammatory response, energy production and apoptosis. Its dysfunction is related to numerous pathological conditions including ischemic brain injury, glioma and glioblastoma multiforme. However, the working mechanism of Panx2 remains unclear. Here, we present the cryo-electron microscopy structure of human Panx2 at a resolution of 3.4 Å. Panx2 structure assembles as a heptamer, forming an exceptionally wide channel pore across the transmembrane and intracellular domains, which is compatible with ATP permeation. Comparing Panx2 with Panx1 structures in different states reveals that the Panx2 structure corresponds to an open channel state. A ring of seven arginine residues located at the extracellular entrance forms the narrowest site of the channel, which serves as the critical molecular filter controlling the permeation of substrate molecules. This is further verified by molecular dynamics simulations and ATP release assays. Our studies reveal the architecture of the Panx2 channel and provide insights into the molecular mechanism of its channel gating.
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Harcha PA, López-López T, Palacios AG, Sáez PJ. Pannexin Channel Regulation of Cell Migration: Focus on Immune Cells. Front Immunol 2022; 12:750480. [PMID: 34975840 PMCID: PMC8716617 DOI: 10.3389/fimmu.2021.750480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022] Open
Abstract
The role of Pannexin (PANX) channels during collective and single cell migration is increasingly recognized. Amongst many functions that are relevant to cell migration, here we focus on the role of PANX-mediated adenine nucleotide release and associated autocrine and paracrine signaling. We also summarize the contribution of PANXs with the cytoskeleton, which is also key regulator of cell migration. PANXs, as mechanosensitive ATP releasing channels, provide a unique link between cell migration and purinergic communication. The functional association with several purinergic receptors, together with a plethora of signals that modulate their opening, allows PANX channels to integrate physical and chemical cues during inflammation. Ubiquitously expressed in almost all immune cells, PANX1 opening has been reported in different immunological contexts. Immune activation is the epitome coordination between cell communication and migration, as leukocytes (i.e., T cells, dendritic cells) exchange information while migrating towards the injury site. In the current review, we summarized the contribution of PANX channels during immune cell migration and recruitment; although we also compile the available evidence for non-immune cells (including fibroblasts, keratinocytes, astrocytes, and cancer cells). Finally, we discuss the current evidence of PANX1 and PANX3 channels as a both positive and/or negative regulator in different inflammatory conditions, proposing a general mechanism of these channels contribution during cell migration.
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Affiliation(s)
- Paloma A Harcha
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Tamara López-López
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Adrián G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Pablo J Sáez
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Zhang D, Yin H, Bauer TL, Rogers MP, Velotta JB, Morgan CT, Du W, Xu P, Qian X. Development of a novel miR-3648-related gene signature as a prognostic biomarker in esophageal adenocarcinoma. ANNALS OF TRANSLATIONAL MEDICINE 2022; 9:1702. [PMID: 34988211 PMCID: PMC8667142 DOI: 10.21037/atm-21-6237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/29/2021] [Indexed: 11/06/2022]
Abstract
Background Esophageal adenocarcinoma (EA) is a typical immunogenic malignant tumor with a dismal 5-year survival rate lower than 20%. Although miRNA-3648 (miR-3648) is expressed abnormally in EA, its impact on the tumor immune microenvironment remains unknown. In this study, we sought to identify immune-related genes (IRGs) that are targeted by miR-3648 and develop an EA multigene signature. Methods The gene expression data of 87 EA tumor samples and 67 normal tissue samples from The Cancer Genome Atlas (TCGA) database and the Genotype-Tissue Expression (GTEx) database were downloaded, respectively. Weighted gene co-expression network analysis (WGCNA), the CIBERSORT algorithm, and Cox regression analysis were applied to identify IRGs and to construct a prognostic signature and nomogram. Results MiR-3648 was expectedly highly expressed in EA tumor tissues (P=2.6e-8), and related to the infiltration of activated natural killer cells (NK cells) and activated CD4 T lymphocytes (CD4 cells). A total of 70 miR-3648-targeted genes related to immune cell infiltration were identified. Among them, 4 genes (C10orf55, DLL4, PANX2, and NKAIN1) were closely related to overall survival (OS), and were thus selected to construct a 4-gene risk score (RS). The RS had a superior capability to predict OS [area under the curve (AUC) =0.740 for 1 year; AUC =0.717 for 3 years; AUC =0.622 for 5 years]. A higher score was indicative of a poorer prognosis than a lower score [hazard ratio (HR) =2.71; 95% confidence interval (CI): 1.45-5.09; P=0.002]. Furthermore, the nomogram formed by combining the RS and the TNM classification of malignant tumors (TNM stage) improved the accuracy of survival prediction [Harrell's concordance index (C-index) =0.698]. Conclusions MiR-3648 may play a critical role in EA pathogenesis. The novel 4-gene signature may serve as a prognostic tool to manage patients with EA.
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Affiliation(s)
- Donglei Zhang
- Department of Thoracic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hang Yin
- Department of Thoracic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Thomas L Bauer
- Department of General Surgery, Jersey Shore University Medical Center, Neptune, NJ, USA
| | - Michael P Rogers
- Department of Surgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA
| | - Jeffrey B Velotta
- Department of Thoracic Surgery, Oakland Medical Center, Kaiser Permanente Northern California, Oakland, CA, USA
| | - Clinton T Morgan
- Division of Cardiothoracic Surgery, Department of Surgery, University of Kentucky, Lexington, KY, USA
| | - Weijia Du
- Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Ping Xu
- Division of Gastroenterology and Hepatology, Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Institute of Digestive Disease, Shanghai, China
| | - Xiaozhe Qian
- Department of Thoracic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Sanchez-Pupo RE, O'Donnell BL, Johnston D, Gyenis L, Litchfield DW, Penuela S. Pannexin 2 is expressed in murine skin and promotes UVB-induced apoptosis of keratinocytes. Mol Biol Cell 2022; 33:ar24. [PMID: 34985913 PMCID: PMC9250380 DOI: 10.1091/mbc.e21-08-0387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pannexins (PANX) are a family of three channel-forming membrane glycoproteins expressed in the skin. Previous studies have focused on the role of PANX1 and PANX3 in the regulation of cellular functions in skin cells while PANX2, the largest member of this protein family, has not been investigated. In the current study, we explored the temporal PANX2 expression in murine skin and found that one Panx2 splice variant (Panx2-202) tends to be more abundant at the protein level and is continuously expressed in developed skin. PANX2 was detected in the suprabasal layers of the mouse epidermis and up-regulated in an in vitro model of rat epidermal keratinocyte differentiation. Furthermore, we show that in apoptotic rat keratinocytes, upon UV light B (UVB)-induced caspase-3/7 activation, ectopically overexpressed PANX2 is cleaved in its C-terminal domain at the D416 residue without increasing the apoptotic rate measured by caspase-3/7 activation. Notably, CRISPR-Cas9 mediated genetic deletion of rat Panx2 delays but does not impair caspase-3/7 activation and cytotoxicity in UVB-irradiated keratinocytes. We propose that endogenous PANX2 expression in keratinocytes promotes cell death after UVB insult and may contribute to skin homeostasis.
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Affiliation(s)
- Rafael E Sanchez-Pupo
- Department of Anatomy and Cell Biology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Brooke L O'Donnell
- Department of Anatomy and Cell Biology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Laszlo Gyenis
- Department of Biochemistry, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - David W Litchfield
- Department of Biochemistry, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.,Department of Oncology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.,Department of Oncology, Division of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
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Zhao S, Li P, Wu W, Wang Q, Qian B, Li X, Shen M. Roles of ferroptosis in urologic malignancies. Cancer Cell Int 2021; 21:676. [PMID: 34922551 PMCID: PMC8684233 DOI: 10.1186/s12935-021-02264-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/14/2021] [Indexed: 12/25/2022] Open
Abstract
Ferroptosis, an iron-dependent form of non-apoptotic cell death, is believed to strongly contribute to the pathogenesis of multiple cancers. Recently, the positive association between ferroptosis and urologic malignancies has drawn considerable attention, while a comprehensive review focused on this issue is absent. Based on this review, ferroptosis has been implicated in the development and therapeutic responses of prostate cancer, kidney cancer, and bladder cancer. Mechanistically, a large number of biomolecules and tumor-associated signaling pathways, including DECR1, PANX2, HSPB1, ACOT8, SUV39H1, NCOA4, PI3K-AKT-mTOR signaling, VHL/HIF-2α pathway, and Hippo/TAZ signaling pathway, have been reported to regulate ferroptosis in urologic cancers. Ferroptosis inducers, such as erastin, ART, CPNPs, and quinazolinyl-arylurea derivatives, exert potential therapeutic effects per se and/or enhance the anticancer response of other anticancer drugs in urologic oncology. A better understanding of ferroptosis may provide a promising way to treat therapy-resistant urologic cancers.
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Affiliation(s)
- Shankun Zhao
- Department of Urology, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, 318000, Zhejiang, China
| | - Peng Li
- Department of Urology, Qingdao Women and Children's Hospital, Qingdao, 266000, Shandong, China
| | - Weizhou Wu
- Department of Urology, Maoming People's Hospital, Maoming, 525000, Guangdong, China
| | - Qinzhang Wang
- Department of Urology, The First Affiliated Hospital of Shihezi University Medical School, Shihezi, China
| | - Biao Qian
- Department of Urology, First Affiliated Hospital of Gannan Medical University, Ganzhou, 341000, Jiangxi, China
| | - Xin Li
- Department of Urology, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, 318000, Zhejiang, China.
| | - Maolei Shen
- Department of Urology, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, 318000, Zhejiang, China.
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Laird DW, Penuela S. Pannexin biology and emerging linkages to cancer. Trends Cancer 2021; 7:1119-1131. [PMID: 34389277 DOI: 10.1016/j.trecan.2021.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/16/2021] [Accepted: 07/20/2021] [Indexed: 12/18/2022]
Abstract
Pannexins are a family of glycoproteins that comprises three members, PANX1, PANX2, and PANX3. The widely expressed and interrogated PANX1 forms heptameric membrane channels that primarily serve to connect the cytoplasm to the extracellular milieu by being selectively permeable to small signaling molecules when activated. Apart from notable exceptions, PANX1 in many tumor cells appears to facilitate tumor growth and metastasis, suggesting that pannexin-blocking therapeutics may have utility in cancer. Attenuation of PANX1 function must also consider the fact that PANX1 is found in stromal cells of the tumor microenvironment (TME), including immune cells. This review highlights the key discoveries of the past 5 years that suggest pannexins facilitate, or in some cases inhibit, tumor cell growth and metastasis via direct protein interactions and through the regulated efflux of signaling molecules.
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Affiliation(s)
- Dale W Laird
- Department of Anatomy and Cell Biology, and Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada; Department of Oncology, Divisions of Experimental Oncology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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Abstract
PANX2 forms large-pore channels mediating ATP release in response to physiological and pathological stimuli. Although PANX2 shows involvements in glioma genesis, the underlying mechanism remains unclear. PANX2 mRNA expression was analyzed via Oncomine and was confirmed via Gene Expression Profiling Interactive Analysis (GEPIA). The influence of PANX2 on overall survival (OS) of glioma was evaluated using LinkedOmics and further assessed through Cox regression analysis. The correlated genes with PANX2 acquired from LinkedOmics were validated through GEPIA and cBioPortal. Protein-protein interaction (PPI) of these genes was then obtained using Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape with MCODE plug-in. All the PANX2-related genes underwent Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The correlation between PANX2 and cancer immune infiltrates was evaluated via Tumor Immune Estimation Resource (TIMER). A higher expression of PANX2 only revealed a better OS in brain low grade glioma (LGG). PANX2-related genes in LGG functionally enriched in neuroactive ligand-receptor interaction, synaptic vesicle cycle, and calcium signaling. The hub genes from highest module of PPI were mainly linked to chemical synaptic transmission, plasma membrane, neuropeptide, and the pathway of neuroactive ligand-receptor interaction. Besides, PANX2 expression was negatively associated with infiltrating levels of macrophage, dendritic cells, and CD4+ T cells. This study demonstrated that PANX2 likely participated in LGG pathogenesis by affecting multiple molecular pathways and immune-related processes. PANX2 was associated with LGG prognosis and might become a promising therapeutic target of LGG.
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Affiliation(s)
- XiaoXue Xu
- Department of Neurology, The First
Hospital of China Medical University, Shenyang, China
- Key Laboratory of Neurological Disease
Big Data of Liaoning Province, Shenyang, China
| | - YueHan Hao
- Department of Neurology, The First
Hospital of China Medical University, Shenyang, China
- Key Laboratory of Neurological Disease
Big Data of Liaoning Province, Shenyang, China
| | - Shuang Xiong
- Liaoning Academy of Analytic Science,
Construction Engineering Center of Important Technology Innovation and Research and
Development Base in Liaoning Province, Shenyang, China
| | - ZhiYi He
- Department of Neurology, The First
Hospital of China Medical University, Shenyang, China
- Key Laboratory of Neurological Disease
Big Data of Liaoning Province, Shenyang, China
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Yao Y, Dong S, Zhu C, Hu M, Du B, Tong X. [Down-regulation of pannexin 2 channel enhances cisplatin-induced apoptosis in testicular cancer I-10 cells]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2020; 40:1090-1096. [PMID: 32895173 DOI: 10.12122/j.issn.1673-4254.2020.08.04] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effect of down-regulation of pannexin 2 (Panx-2) channels on cisplatin-induced apoptosis in I-10 cells. METHODS The expression of Panx-2 protein in testicular cancer cells was detected with Western blotting. The testicular cancer cell line I-10 was transfected with two short hairpin RNA (shRNA1 and shRNA2) via Lipofectamine2000, the empty vector (NC group) or Lipofectamine2000 (blank control group), and the changes in the expression of Panx-2 was detected with Western blotting. The effects of transfection with a Panx-2 inhibitor on surviving fraction of the cells treated with cisplatin (16 μmol/L) for 24 h, 48 h and 72 h was assessed with MTT assay, and the clonogenic capacity of the cells was evaluated with colony-forming assay. At 8 h after incubation with 16 μmol/L cisplatin, AnnexinV/PI double staining was used to detect the early apoptosis of the cells. After 24 h of treatment with 16 μmol/L cisplatin, the cells were examined for expressions of caspase-3, Bcl-2 and Bax using Western blotting. RESULTS The expression of Panx-2 was significantly increased in cisplatin-resistant I-10/DDP (P < 0.001) cells and Tcam-2/DDP (P < 0.01) cells as compared with I-10 cells and Tcam-2 cells. Transfection of I-10 cells with shRNA1 and shRNA2 resulted in significantly decreased Panx-2 expression (P < 0.05) and significantly reduced cell surviving fraction (P < 0.001). In the presence of cisplatin, the cells in NC group showed a higher clonogenic efficiency than those in shRNA1 and shRNA2 groups (P < 0.001). The early-stage apoptosis rate of the cells in shRNA1 and shRNA2 groups were significantly higher than that in NC group (P < 0.01). Panx-2 knockdown in I-10 cells significantly increased caspase-3 and Bax expressions (P < 0.05) and significantly decreased the expression of Bcl-2 (P < 0.01). CONCLUSIONS Down-regulation of Panx-2 channel enhances cisplatin-induced apoptosis in cultured testicular cancer cells.
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Affiliation(s)
- Yanxue Yao
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Shuying Dong
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Chenlu Zhu
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Miao Hu
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Baolong Du
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
| | - Xuhui Tong
- School of Pharmacy, Bengbu Medical College, Bengbu 233030, China
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Caufriez A, Böck D, Martin C, Ballet S, Vinken M. Peptide-based targeting of connexins and pannexins for therapeutic purposes. Expert Opin Drug Discov 2020; 15:1213-1222. [PMID: 32539572 DOI: 10.1080/17460441.2020.1773787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Connexin and pannexin (hemi)channels play an important role in paracrine and autocrine signaling pathways. The opening of these cellular pores is linked to a wide range of diseases. Therefore, pharmacological closing of connexin and pannexin (hemi)channels seems a promising therapeutic strategy. However, the currently available inhibitors cope with recurring problems concerning selectivity, specificity, stability and/or solubility. AREAS COVERED A number of peptides that mimic specific regions in the native sequence of connexins and pannexins have the potential to overcome some of these hurdles. In this paper, an overview is provided on these peptide-based inhibitors of connexin and pannexin (hemi)channels for therapeutic purposes. The authors also provide the reader with their expert perspectives on the future of these peptide-based inhibitors. EXPERT OPINION Peptide mimetics can become valuable tools in the treatment of connexin-related and pannexin-related diseases. This can be made possible provided that available peptides are optimized, and new peptide mimetics are designed based on knowledge of the mechanisms underlying the gating control of connexin and pannexin (hemi)channels.
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Affiliation(s)
- Anne Caufriez
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Denise Böck
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Charlotte Martin
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Steven Ballet
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Mathieu Vinken
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
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Liao D, Yang G, Yang Y, Tang X, Huang H, Shao J, Pan Q. Identification of Pannexin 2 as a Novel Marker Correlating with Ferroptosis and Malignant Phenotypes of Prostate Cancer Cells. Onco Targets Ther 2020; 13:4411-4421. [PMID: 32547072 PMCID: PMC7245471 DOI: 10.2147/ott.s249752] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/26/2020] [Indexed: 02/05/2023] Open
Abstract
Purpose Prostate cancer (PCa) is a widespread urinary neoplasm and one of the most prevalent and second most frequent malignancies diagnosed in males worldwide. This study aimed to identify a candidate marker and explore its molecular mechanism in PCa. Methods Gene expression datasets, GSE55945 (n=21) and GSE46602 (n=50), were downloaded from the Gene Expression Omnibus database. Bioinformatic approaches were applied to identify potential markers. Effects of the candidate marker on proliferation, migration, invasion, and ferroptosis (ferrous iron and malondialdehyde (MDA)) in PCa cells and its mechanism were assessed after performing cell transfection. Results A total of 1435 common differentially expressed genes were identified in GSE55945 and GSE46602. Five key gene modules were listed based on a protein–protein interaction network, containing five hub genes. Pannexin 2 (PANX2), a candidate marker was identified, and findings revealed substantial upregulation of its expression levels in PCa cell lines. Blocking expression of PANX2 resulted in suppression of proliferation, migration, and invasion in PCa cells, while increasing ferrous iron and MDA levels. However, these effects were rescued by Nrf2 activator, oltipraz. The Nrf2 signaling pathway was consequently applied to determine underlying mechanism of PANX2 in PCa cells. We established that silencing PANX2 remarkably reduced protein expression levels in members of Nrf2 signaling pathway (Nrf2, HO-1, and FTH1). Conclusion Our study demonstrated that PANX2 is implicated in the pathogenesis of PCa, which regulates malignant phenotypes and ferroptosis through Nrf2 signaling pathway, and maybe a potential therapeutic target for PCa.
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Affiliation(s)
- Duwu Liao
- Department of Urology Surgery, The Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, Sichuan, People's Republic of China
| | - Guang Yang
- Department of Urology Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Yuan Yang
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Xueyong Tang
- Department of Dermatology, Chongqing Traditional Chinese Medicine Hospital, Chongqing, People's Republic of China
| | - Haixia Huang
- Department of Critical Care Medicine, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing, People's Republic of China
| | - Jichun Shao
- Department of Urology Surgery, The Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, Sichuan, People's Republic of China
| | - Qi Pan
- Department of Dermatology, Chongqing Traditional Chinese Medicine Hospital, Chongqing, People's Republic of China
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Brocardo L, Acosta LE, Piantanida AP, Rela L. Beneficial and Detrimental Remodeling of Glial Connexin and Pannexin Functions in Rodent Models of Nervous System Diseases. Front Cell Neurosci 2019; 13:491. [PMID: 31780897 PMCID: PMC6851021 DOI: 10.3389/fncel.2019.00491] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/17/2019] [Indexed: 01/30/2023] Open
Abstract
A variety of glial cell functions are supported by connexin and pannexin proteins. These functions include the modulation of synaptic gain, the control of excitability through regulation of the ion and neurotransmitter composition of the extracellular milieu and the promotion of neuronal survival. Connexins and pannexins support these functions through diverse molecular mechanisms, including channel and non-channel functions. The former comprise the formation of gap junction-mediated networks supported by connexin intercellular channels and the formation of pore-like membrane structures or hemichannels formed by both connexins and pannexins. Non-channel functions involve adhesion properties and the participation in signaling intracellular cascades. Pathological conditions of the nervous system such as ischemia, neurodegeneration, pathogen infection, trauma and tumors are characterized by distinctive remodeling of connexin expression and function. However, whether these changes can be interpreted as part of the pathogenesis, or as beneficial compensatory effects, remains under debate. Here we review the available evidence addressing this matter with a special emphasis in mouse models with selective manipulation of glial connexin and pannexin proteins in vivo. We postulate that the beneficial vs. detrimental effects of glial connexin remodeling in pathological conditions depend on the impact of remodeling on the different connexin and pannexin channel and non-channel functions, on the characteristics of the inflammatory environment and on the type of interaction among glial cells types.
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Affiliation(s)
- Lucila Brocardo
- Grupo de Neurociencia de Sistemas, Facultad de Medicina, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Luis Ernesto Acosta
- Grupo de Neurociencia de Sistemas, Facultad de Medicina, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ana Paula Piantanida
- Grupo de Neurociencia de Sistemas, Facultad de Medicina, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Lorena Rela
- Grupo de Neurociencia de Sistemas, Facultad de Medicina, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
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13
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Liu H, Yuan M, Yao Y, Wu D, Dong S, Tong X. In vitro effect of Pannexin 1 channel on the invasion and migration of I-10 testicular cancer cells via ERK1/2 signaling pathway. Biomed Pharmacother 2019; 117:109090. [PMID: 31202174 DOI: 10.1016/j.biopha.2019.109090] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/30/2019] [Accepted: 06/04/2019] [Indexed: 12/14/2022] Open
Abstract
Pannexin (Panx) plays a crucial role in several cellular processes such as immune cell death, cell proliferation, invasion, and migration, apoptosis, and autophagy. However, the role of Panx in regulating cell migration and invasion in testicular cancer remains to be elucidated. In the present study, we determined the correlation between Panx-1 channel function and migration and invasion in I-10 testicular cancer cells. Transwell and wound healing assays showed that inhibition of Panx-1 by carbenoxolone (CBX) and probenecid (PBN) attenuated the migration and invasion of testicular cancer cells in vitro. Moreover, knockdown of Panx-1 with short hairpin RNA (shRNA) remarkably decreased the migration and invasion ability of I-10 cells. In shRNA-transfected cells, extracellular ATP (released through Panx channel) was also found to be decreased. Similarly, overexpression of Panx-1 with mPanx-1 increased the migration and invasion ability of I-10 cells. Moreover, we found that in mPanx-1-transfected cells treated with U0126 (inhibitor of p-ERK1/2), the migration and invasion of I-10 cells were remarkably attenuated. Overall, increased Panx-1 promotes migration and invasion in testicular cancer cells, and the effect is probably be related with ERK1/2 kinase activity. Thus, Panx-1 can serve as a potential therapeutic target for the treatment of testicular cancer.
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Affiliation(s)
- Haofeng Liu
- School of Pharmacy, Bengbu Medical College, Anhui, Bengbu, 233030, PR China
| | - Min Yuan
- School of Pharmacy, Bengbu Medical College, Anhui, Bengbu, 233030, PR China
| | - Yanxue Yao
- School of Pharmacy, Bengbu Medical College, Anhui, Bengbu, 233030, PR China
| | - Dandan Wu
- College of Life Sciences, Nanjing University, Jiangsu, Nanjing, 210093, PR China
| | - Shuying Dong
- School of Pharmacy, Bengbu Medical College, Anhui, Bengbu, 233030, PR China
| | - Xuhui Tong
- School of Pharmacy, Bengbu Medical College, Anhui, Bengbu, 233030, PR China.
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Pannexin 2 Localizes at ER-Mitochondria Contact Sites. Cancers (Basel) 2019; 11:cancers11030343. [PMID: 30862038 PMCID: PMC6468579 DOI: 10.3390/cancers11030343] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/22/2019] [Accepted: 02/27/2019] [Indexed: 01/02/2023] Open
Abstract
Endomembrane specialization allows functional compartmentalization but imposes physical constraints to information flow within the cell. However, the evolution of an endomembrane system was associated with the emergence of contact sites facilitating communication between membrane-bound organelles. Contact sites between the endoplasmic reticulum (ER) and mitochondria are highly conserved in terms of their morphological features but show surprising molecular diversity within and across eukaryote species. ER-mitochondria contact sites are thought to regulate key processes in oncogenesis but their molecular composition remains poorly characterized in mammalian cells. In this study, we investigate the localization of pannexin 2 (Panx2), a membrane channel protein showing tumor-suppressing properties in cancer cells. Using a combination of subcellular fractionation, particle tracking in live-cell, and immunogold electron microscopy, we show that Panx2 localizes at ER-mitochondria contact sites in mammalian cells and sensitizes cells to apoptotic stimuli.
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15
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Kim KM, Hussein UK, Bae JS, Park SH, Kwon KS, Ha SH, Park HS, Lee H, Chung MJ, Moon WS, Kang MJ, Jang KY. The Expression Patterns of FAM83H and PANX2 Are Associated With Shorter Survival of Clear Cell Renal Cell Carcinoma Patients. Front Oncol 2019; 9:14. [PMID: 30723706 PMCID: PMC6349742 DOI: 10.3389/fonc.2019.00014] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/04/2019] [Indexed: 12/21/2022] Open
Abstract
FAM83H is primarily known for its role in amelogenesis; however, recent reports suggest FAM83H might be involved in tumorigenesis. Although the studies of FAM83H in kidney cancer are limited, a search of the public database shows a significant association between FAM83H and pannexin-2 (PANX2) in clear cell renal cell carcinomas (CCRCCs). Therefore, we evaluated the clinicopathological significance of the immunohistochemical expression of FAM83H and PANX2 in 199 CCRCC patients. The expression of FAM83H and PANX2 were significantly associated with each other. In univariate analysis, individual, and co-expression pattern of FAM83H and PANX2 was significantly associated with shorter overall survival (OS) and relapse-free survival (RFS) of CCRCC patients: nuclear expression of FAM83H (OS; P < 0.001, RFS; P < 0.001), cytoplasmic expression of FAM83H (OS; P < 0.001, RFS; P < 0.001), nuclear expression of PANX2 (OS; P < 0.001, RFS; P < 0.001), cytoplasmic expression of PANX2 (OS; P < 0.001, RFS; P < 0.001), co-expression pattern of nuclear FAM83H and nuclear PANX2 (OS; P < 0.001, RFS; P < 0.001). In multivariate analysis, nuclear expression of FAM83H (OS; P < 0.001, RFS; P = 0.003) and the co-expression pattern of nuclear FAM83H and PANX2 (OS; P < 0.001, RFS; P < 0.001) were independent indicators of shorter survival of CCRCC patients. Cytoplasmic expression of FAM83H was associated with shorter RFS (P = 0.030) in multivariate analysis. In Caki-1 and Caki-2 CCRCC cells, knock-down of FAM83H decreased PANX2 expression and cell proliferation, and overexpression of FAM83H increased PANX2 expression and cell proliferation. These results suggest that FAM83H and PANX2 might be involved in the progression of CCRCC in a co-operative manner, and their expression might be used as novel prognostic indicators for CCRCC patients.
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Affiliation(s)
- Kyoung Min Kim
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea.,Research Institute for Endocrine Sciences, Chonbuk National University, Jeonju, South Korea
| | - Usama Khamis Hussein
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - Jun Sang Bae
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea
| | - See-Hyoung Park
- Department of Bio and Chemical Engineering, Hongik University, Sejong, South Korea
| | - Keun Sang Kwon
- Department of Preventive Medicine, Chonbuk National University Medical School, Jeonju, South Korea
| | - Sang Hoon Ha
- Division of Biotechnology, Chonbuk National University, Iksan, South Korea
| | - Ho Sung Park
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea
| | - Ho Lee
- Department of Forensic Medicine, Chonbuk National University Medical School, Jeonju, South Korea
| | - Myoung Ja Chung
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea
| | - Woo Sung Moon
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea
| | - Myoung Jae Kang
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea
| | - Kyu Yun Jang
- Department of Pathology, Chonbuk National University Medical School, Jeonju, South Korea.,Research Institute of Clinical Medicine of Chonbuk National University, Jeonju, South Korea.,Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, South Korea.,Research Institute for Endocrine Sciences, Chonbuk National University, Jeonju, South Korea
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16
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Abudara V, Retamal MA, Del Rio R, Orellana JA. Synaptic Functions of Hemichannels and Pannexons: A Double-Edged Sword. Front Mol Neurosci 2018; 11:435. [PMID: 30564096 PMCID: PMC6288452 DOI: 10.3389/fnmol.2018.00435] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/08/2018] [Indexed: 01/18/2023] Open
Abstract
The classical view of synapses as the functional contact between presynaptic and postsynaptic neurons has been challenged in recent years by the emerging regulatory role of glial cells. Astrocytes, traditionally considered merely supportive elements are now recognized as active modulators of synaptic transmission and plasticity at the now so-called "tripartite synapse." In addition, an increasing body of evidence indicates that beyond immune functions microglia also participate in various processes aimed to shape synaptic plasticity. Release of neuroactive compounds of glial origin, -process known as gliotransmission-, constitute a widespread mechanism through which glial cells can either potentiate or reduce the synaptic strength. The prevailing vision states that gliotransmission depends on an intracellular Ca2+/exocytotic-mediated release; notwithstanding, growing evidence is pointing at hemichannels (connexons) and pannexin channels (pannexons) as alternative non-vesicular routes for gliotransmitters efflux. In concurrence with this novel concept, both hemichannels and pannexons are known to mediate the transfer of ions and signaling molecules -such as ATP and glutamate- between the cytoplasm and the extracellular milieu. Importantly, recent reports show that glial hemichannels and pannexons are capable to perceive synaptic activity and to respond to it through changes in their functional state. In this article, we will review the current information supporting the "double edge sword" role of hemichannels and pannexons in the function of central and peripheral synapses. At one end, available data support the idea that these channels are chief components of a feedback control mechanism through which gliotransmitters adjust the synaptic gain in either resting or stimulated conditions. At the other end, we will discuss how the excitotoxic release of gliotransmitters and [Ca2+]i overload linked to the opening of hemichannels/pannexons might impact cell function and survival in the nervous system.
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Affiliation(s)
- Verónica Abudara
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States.,Programa de Comunicación Celular en Cáncer, Instituto de Ciencias e Innovación en Medicina, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
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17
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Sanchez-Pupo RE, Johnston D, Penuela S. N-Glycosylation Regulates Pannexin 2 Localization but Is Not Required for Interacting with Pannexin 1. Int J Mol Sci 2018; 19:ijms19071837. [PMID: 29932112 PMCID: PMC6073767 DOI: 10.3390/ijms19071837] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/16/2018] [Accepted: 06/20/2018] [Indexed: 02/07/2023] Open
Abstract
Pannexins (Panx1, 2, 3) are channel-forming glycoproteins expressed in mammalian tissues. We previously reported that N-glycosylation acts as a regulator of the localization and intermixing of Panx1 and Panx3, but its effects on Panx2 are currently unknown. Panx1 and Panx2 intermixing can regulate channel properties, and both pannexins have been implicated in neuronal cell death after ischemia. Our objectives were to validate the predicted N-glycosylation site of Panx2 and to study the effects of Panx2 glycosylation on localization and its capacity to interact with Panx1. We used site-directed mutagenesis, enzymatic de-glycosylation, cell-surface biotinylation, co-immunoprecipitation, and confocal microscopy. Our results showed that N86 is the only N-glycosylation site of Panx2. Panx2 and the N86Q mutant are predominantly localized to the endoplasmic reticulum (ER) and cis-Golgi matrix with limited cell surface localization was seen only in the presence of Panx1. The Panx2 N86Q mutant is glycosylation-deficient and tends to aggregate in the ER reducing its cell surface trafficking but it can still interact with Panx1. Our study indicates that N-glycosylation may be important for folding and trafficking of Panx2. We found that the un-glycosylated forms of Panx1 and 2 can readily interact, regulating their localization and potentially their channel function in cells where they are co-expressed.
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Affiliation(s)
- Rafael E Sanchez-Pupo
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A5C1, Canada.
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18
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Connexins and Pannexins: Important Players in Tumorigenesis, Metastasis and Potential Therapeutics. Int J Mol Sci 2018; 19:ijms19061645. [PMID: 29865195 PMCID: PMC6032133 DOI: 10.3390/ijms19061645] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 12/15/2022] Open
Abstract
Since their characterization more than five decades ago, gap junctions and their structural proteins-the connexins-have been associated with cancer cell growth. During that period, the accumulation of data and molecular knowledge about this association revealed an apparent contradictory relationship between them and cancer. It appeared that if gap junctions or connexins can down regulate cancer cell growth they can be also implied in the migration, invasion and metastatic dissemination of cancer cells. Interestingly, in all these situations, connexins seem to be involved through various mechanisms in which they can act either as gap-junctional intercellular communication mediators, modulators of signalling pathways through their interactome, or as hemichannels, which mediate autocrine/paracrine communication. This complex involvement of connexins in cancer progression is even more complicated by the fact that their hemichannel function may overlap with other gap junction-related proteins, the pannexins. Despite this complexity, the possible involvements of connexins and pannexins in cancer progression and the elucidation of the mechanisms they control may lead to use them as new targets to control cancer progression. In this review, the involvements of connexins and pannexins in these different topics (cancer cell growth, invasion/metastasis process, possible cancer therapeutic targets) are discussed.
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19
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Xu J, He J, Huang H, Peng R, Xi J. MicroRNA-423-3p promotes glioma growth by targeting PANX2. Oncol Lett 2018; 16:179-188. [PMID: 29928399 PMCID: PMC6006452 DOI: 10.3892/ol.2018.8636] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/15/2018] [Indexed: 01/08/2023] Open
Abstract
Previously, a number of microRNAs (miRs) have been identified to participate in the development and progression of glioma via the regulation of their target genes. However, the molecular mechanisms underlying the effect of miR-423-3p in glioma growth remain unclear. In the present study, the reverse transcription-quantitative polymerase chain reaction and western blotting were used to assess the mRNA and protein expression levels of miR-423-3p, respectively. An MTT assay and flow cytometry were performed to determine cell proliferation and apoptosis, respectively. A luciferase reporter gene assay was performed to determine the target association between pannexin 2 (PANX2) and miR-423-3p. It was revealed that miR-423-3p was significantly upregulated in glioma tissues compared with normal brain tissues, and the increased expression of miR-423-3p was significantly associated with an advanced grade as well as a poorer prognosis of patients with glioma. Inhibition of miR-423-3p using an miR-423-3p inhibitor resulted in the decreased proliferation of glioma U251 and U87MG Uppsala cells, and the induction of apoptosis. PANX2 was identified as a novel target gene of miR-423-3p, and the expression of PANX2 was revealed to be increased in U251 and U87MG Uppsala cells when miR-423-3p was inhibited. Knockdown of PANX2 attenuated the effects of miR-423-3p inhibition on glioma cell proliferation and apoptosis. Furthermore, PANX2 was significantly downregulated in glioma tissues compared with normal brain tissues, and its levels were markedly lower in World Health Organization (WHO) stage III–IV gliomas compared with WHO stage I–II gliomas. Additionally, the expression levels of PANX2 were identified to be inversely correlated with miR-423-3p expression levels in glioma tissues. Consequently, targeting miR-423-3p may inhibit glioma growth via the upregulation of PANX2.
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Affiliation(s)
- Jing Xu
- Department of Otolaryngology, Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Jian He
- Department of Otolaryngology, Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - He Huang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Renjun Peng
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Jian Xi
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
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20
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Chiu YH, Schappe MS, Desai BN, Bayliss DA. Revisiting multimodal activation and channel properties of Pannexin 1. J Gen Physiol 2017; 150:19-39. [PMID: 29233884 PMCID: PMC5749114 DOI: 10.1085/jgp.201711888] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 11/09/2017] [Indexed: 12/23/2022] Open
Abstract
Pannexin 1 (Panx1) forms plasma membrane ion channels that are widely expressed throughout the body. Panx1 activation results in the release of nucleotides such as adenosine triphosphate and uridine triphosphate. Thus, these channels have been implicated in diverse physiological and pathological functions associated with purinergic signaling, such as apoptotic cell clearance, blood pressure regulation, neuropathic pain, and excitotoxicity. In light of this, substantial attention has been directed to understanding the mechanisms that regulate Panx1 channel expression and activation. Here we review accumulated evidence for the various activation mechanisms described for Panx1 channels and, where possible, the unitary channel properties associated with those forms of activation. We also emphasize current limitations in studying Panx1 channel function and propose potential directions to clarify the exciting and expanding roles of Panx1 channels.
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Affiliation(s)
- Yu-Hsin Chiu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Michael S Schappe
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Bimal N Desai
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA
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21
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Regulation of Skeletal Muscle Myoblast Differentiation and Proliferation by Pannexins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 925:57-73. [PMID: 27518505 DOI: 10.1007/5584_2016_53] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Pannexins are newly discovered channels that are now recognized as mediators of adenosine triphosphate release from several cell types allowing communication with the extracellular environment. Pannexins have been associated with various physiological and pathological processes including apoptosis, inflammation, and cancer. However, it is only recently that our work has unveiled a role for Pannexin 1 and Pannexin 3 as novel regulators of skeletal muscle myoblast proliferation and differentiation. Myoblast differentiation is an ordered multistep process that includes withdrawal from the cell cycle and the expression of key myogenic factors leading to myoblast differentiation and fusion into multinucleated myotubes. Eventually, myotubes will give rise to the diverse muscle fiber types that build the complex skeletal muscle architecture essential for body movement, postural behavior, and breathing. Skeletal muscle cell proliferation and differentiation are crucial processes required for proper skeletal muscle development during embryogenesis, as well as for the postnatal skeletal muscle regeneration that is necessary for muscle repair after injury or exercise. However, defects in skeletal muscle cell differentiation and/or deregulation of cell proliferation are involved in various skeletal muscle pathologies. In this review, we will discuss the expression of pannexins and their post-translational modifications in skeletal muscle, their known functions in various steps of myogenesis, including myoblast proliferation and differentiation, as well as their possible roles in skeletal muscle development, regeneration, and diseases such as Duchenne muscular dystrophy.
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22
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Berchtold LA, Miani M, Diep TA, Madsen AN, Cigliola V, Colli M, Krivokapic JM, Pociot F, Eizirik DL, Meda P, Holst B, Billestrup N, Størling J. Pannexin-2-deficiency sensitizes pancreatic β-cells to cytokine-induced apoptosis in vitro and impairs glucose tolerance in vivo. Mol Cell Endocrinol 2017; 448:108-121. [PMID: 28390953 DOI: 10.1016/j.mce.2017.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/20/2017] [Accepted: 04/03/2017] [Indexed: 02/07/2023]
Abstract
Pannexins (Panx's) are membrane proteins involved in a variety of biological processes, including cell death signaling and immune functions. The role and functions of Panx's in pancreatic β-cells remain to be clarified. Here, we show Panx1 and Panx2 expression in isolated islets, primary β-cells, and β-cell lines. The expression of Panx2, but not Panx1, was downregulated by interleukin-1β (IL-1β) plus interferon-γ (IFNγ), two pro-inflammatory cytokines suggested to contribute to β-cell demise in type 1 diabetes (T1D). siRNA-mediated knockdown (KD) of Panx2 aggravated cytokine-induced apoptosis in rat INS-1E cells and primary rat β-cells, suggesting anti-apoptotic properties of Panx2. An anti-apoptotic function of Panx2 was confirmed in isolated islets from Panx2-/- mice and in human EndoC-βH1 cells. Panx2 KD was associated with increased cytokine-induced activation of STAT3 and higher expression of inducible nitric oxide synthase (iNOS). Glucose-stimulated insulin release was impaired in Panx2-/- islets, and Panx2-/- mice subjected to multiple low-dose Streptozotocin (MLDS) treatment, a model of T1D, developed more severe diabetes compared to wild type mice. These data suggest that Panx2 is an important regulator of the insulin secretory capacity and apoptosis in pancreatic β-cells.
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Affiliation(s)
- Lukas A Berchtold
- Copenhagen Diabetes Research Center, Pediatric Department, University Hospital Herlev, Denmark; Department of Biomedical Sciences, University of Copenhagen, Denmark
| | - Michela Miani
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Belgium
| | - Thi A Diep
- Department of Neurosciences and Pharmacology, University of Copenhagen, Denmark
| | - Andreas N Madsen
- Department of Neurosciences and Pharmacology, University of Copenhagen, Denmark
| | - Valentina Cigliola
- Department of Genetic Medicine and Development, University of Geneva, Switzerland
| | - Maikel Colli
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Belgium
| | | | - Flemming Pociot
- Copenhagen Diabetes Research Center, Pediatric Department, University Hospital Herlev, Denmark
| | - Decio L Eizirik
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Belgium
| | - Paolo Meda
- Department of Cellular Physiology and Metabolism, University of Geneva, Switzerland
| | - Birgitte Holst
- Department of Neurosciences and Pharmacology, University of Copenhagen, Denmark
| | - Nils Billestrup
- Department of Biomedical Sciences, University of Copenhagen, Denmark
| | - Joachim Størling
- Copenhagen Diabetes Research Center, Pediatric Department, University Hospital Herlev, Denmark.
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Xu J, Chen L, Li L. Pannexin hemichannels: A novel promising therapy target for oxidative stress related diseases. J Cell Physiol 2017; 233:2075-2090. [PMID: 28295275 DOI: 10.1002/jcp.25906] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 03/09/2017] [Indexed: 12/16/2022]
Abstract
Pannexins, which contain three subtypes: pannexin-1, -2, and -3, are vertebrate glycoproteins that form non-junctional plasma membrane intracellular hemichannels via oligomerization. Oxidative stress refers to an imbalance of the generation and elimination of reactive oxygen species (ROS). Studies have shown that elevated ROS levels are pivotal in the development of a variety of diseases. Recent studies indicate that the occurrence of these oxidative stress related diseases is associated with pannexin hemichannels. It is also reported that pannexins regulate the production of ROS which in turn may increase the opening of pannexin hemichannels. In this paper, we review recent researches about the important role of pannexin hemichannels in oxidative stress related diseases. Thus, pannexin hemichannels, novel therapeutic targets, hold promise in managing oxidative stress related diseases such as the tumor, inflammatory bowel diseases (IBD), pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), cardiovascular disease, insulin resistance (IR), and neural degeneration diseases.
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Affiliation(s)
- Jin Xu
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Linxi Chen
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Lanfang Li
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
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24
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Mahas A, Potluri K, Kent MN, Naik S, Markey M. Copy number variation in archival melanoma biopsies versus benign melanocytic lesions. Cancer Biomark 2017; 16:575-97. [PMID: 27002761 DOI: 10.3233/cbm-160600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Skin melanocytes can give rise to benign and malignant neoplasms. Discrimination of an early melanoma from an unusual/atypical benign nevus can represent a significant challenge. However, previous studies have shown that in contrast to benign nevi, melanoma demonstrates pervasive chromosomal aberrations. OBJECTIVE This substantial difference between melanoma and benign nevi can be exploited to discriminate between melanoma and benign nevi. METHODS Array-comparative genomic hybridization (aCGH) is an approach that can be used on DNA extracted from formalin-fixed paraffin-embedded (FFPE) tissues to assess the entire genome for the presence of changes in DNA copy number. In this study, high resolution, genome-wide single-nucleotide polymorphism (SNP) arrays were utilized to perform comprehensive and detailed analyses of recurrent copy number aberrations in 41 melanoma samples in comparison with 21 benign nevi. RESULTS We found statistically significant copy number gains and losses within melanoma samples. Some of the identified aberrations are previously implicated in melanoma. Moreover, novel regions of copy number alterations were identified, revealing new candidate genes potentially involved in melanoma pathogenesis. CONCLUSIONS Taken together, these findings can help improve melanoma diagnosis and introduce novel melanoma therapeutic targets.
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Affiliation(s)
- Ahmed Mahas
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Keerti Potluri
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Michael N Kent
- Department of Dermatology, Wright State University Boonshoft School of Medicine, Dayton, OH, USA.,Dermatopathology Laboratory of Central States, Dayton, OH, USA
| | - Sameep Naik
- Dermatopathology Laboratory of Central States, Dayton, OH, USA
| | - Michael Markey
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
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Abstract
Fifty years ago, tumour cells were found to lack electrical coupling, leading to the hypothesis that loss of direct intercellular communication is commonly associated with cancer onset and progression. Subsequent studies linked this phenomenon to gap junctions composed of connexin proteins. Although many studies support the notion that connexins are tumour suppressors, recent evidence suggests that, in some tumour types, they may facilitate specific stages of tumour progression through both junctional and non-junctional signalling pathways. This Timeline article highlights the milestones connecting gap junctions to cancer, and underscores important unanswered questions, controversies and therapeutic opportunities in the field.
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Affiliation(s)
- Trond Aasen
- (Co-corresponding authors) Correspondence to
T.A. () and D.W.L.
()
| | - Marc Mesnil
- STIM Laboratory ERL 7368 CNRS - Faculté des Sciences
Fondamentales et Appliquées, Université de Poitiers, Poitiers,
France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, The Life
Sciences Institute, University of British Columbia, Vancouver, British
Columbia, Canada
| | - Paul D. Lampe
- Translational Research Program, Fred Hutchinson Cancer Research
Center, Seattle, United States
| | - Dale W. Laird
- (Co-corresponding authors) Correspondence to
T.A. () and D.W.L.
()
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26
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Crespo Yanguas S, Willebrords J, Johnstone SR, Maes M, Decrock E, De Bock M, Leybaert L, Cogliati B, Vinken M. Pannexin1 as mediator of inflammation and cell death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:51-61. [PMID: 27741412 DOI: 10.1016/j.bbamcr.2016.10.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 10/07/2016] [Accepted: 10/08/2016] [Indexed: 02/06/2023]
Abstract
Pannexins form channels at the plasma membrane surface that establish a pathway for communication between the cytosol of individual cells and their extracellular environment. By doing so, pannexin signaling dictates several physiological functions, but equally underlies a number of pathological processes. Indeed, pannexin channels drive inflammation by assisting in the activation of inflammasomes, the release of pro-inflammatory cytokines, and the activation and migration of leukocytes. Furthermore, these cellular pores facilitate cell death, including apoptosis, pyroptosis and autophagy. The present paper reviews the roles of pannexin channels in inflammation and cell death. In a first part, a state-of-the-art overview of pannexin channel structure, regulation and function is provided. In a second part, the mechanisms behind their involvement in inflammation and cell death are discussed.
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Affiliation(s)
- Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Scott R Johnstone
- College of Medical, Veterinary and Life Sciences, British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Ghent University, Gent, Belgium
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium.
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27
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Diezmos EF, Bertrand PP, Liu L. Purinergic Signaling in Gut Inflammation: The Role of Connexins and Pannexins. Front Neurosci 2016; 10:311. [PMID: 27445679 PMCID: PMC4925662 DOI: 10.3389/fnins.2016.00311] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/20/2016] [Indexed: 12/13/2022] Open
Abstract
Purinergic receptors play an important role in inflammation, and can be activated by ATP released via pannexin channels and/or connexin hemichannels. The purinergic P2X7 receptor (P2X7R) is of interest since it is involved in apoptosis when activated. Most studies focus on the influence of pannexin-1 (Panx1) and connexin 43 (Cx43) on ATP release and how it affects P2X7R function during inflammation. Inflammatory bowel disease (IBD) is characterized by uncontrolled inflammation within the gastrointestinal system. At present, the pathophysiology of this disease remains largely unknown but it may involve the interplay between P2X7R, Panx1, and Cx43. There are two main types of IBD, ulcerative colitis and Crohn's disease, that are classified by their location and frequency of inflammation. Current research suggests that alterations to normal functioning of innate and adaptive immunity may be a factor in disease progression. The involvement of purinergic receptors, connexins, and pannexins in IBD is a relatively novel notion in the context of gastrointestinal inflammation, and has been explored by various research groups. Thus, the present review focuses on the current research involving connexins, pannexins, and purinergic receptors within the gut and enteric nervous system, and will examine their involvement in inflammation and the pathophysiology of IBD.
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Affiliation(s)
- Erica F Diezmos
- School of Medical Sciences, University of New South Wales Sydney, NSW, Australia
| | - Paul P Bertrand
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia; School of Medical Sciences, RMIT UniversityBundoora, VIC, Australia
| | - Lu Liu
- School of Medical Sciences, University of New South Wales Sydney, NSW, Australia
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28
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Abstract
Communication among cells via direct cell-cell contact by connexin gap junctions, or between cell and extracellular environment via pannexin channels or connexin hemichannels, is a key factor in cell function and tissue homeostasis. Upon malignant transformation in different cancer types, the dysregulation of these connexin and pannexin channels and their effect in cellular communication, can either enhance or suppress tumorigenesis and metastasis. In this review, we will highlight the latest reports on the role of the well characterized connexin family and its ability to form gap junctions and hemichannels in cancer. We will also introduce the more recently discovered family of pannexin channels and our current knowledge about their involvement in cancer progression.
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Affiliation(s)
- Jean X Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, N6A5C1, Canada.
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29
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Cogliati B, Mennecier G, Willebrords J, Da Silva TC, Maes M, Pereira IVA, Crespo-Yanguas S, Hernandez-Blazquez FJ, Dagli MLZ, Vinken M. Connexins, Pannexins, and Their Channels in Fibroproliferative Diseases. J Membr Biol 2016; 249:199-213. [PMID: 26914707 DOI: 10.1007/s00232-016-9881-6] [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] [Received: 10/21/2015] [Accepted: 02/16/2016] [Indexed: 12/13/2022]
Abstract
Cellular and molecular mechanisms of wound healing, tissue repair, and fibrogenesis are established in different organs and are essential for the maintenance of function and tissue integrity after cell injury. These mechanisms are also involved in a plethora of fibroproliferative diseases or organ-specific fibrotic disorders, all of which are associated with the excessive deposition of extracellular matrix components. Fibroblasts, which are key cells in tissue repair and fibrogenesis, rely on communicative cellular networks to ensure efficient control of these processes and to prevent abnormal accumulation of extracellular matrix into the tissue. Despite the significant impact on human health, and thus the epidemiologic relevance, there is still no effective treatment for most fibrosis-related diseases. This paper provides an overview of current concepts and mechanisms involved in the participation of cellular communication via connexin-based pores as well as pannexin-based channels in the processes of tissue repair and fibrogenesis in chronic diseases. Understanding these mechanisms may contribute to the development of new therapeutic strategies to clinically manage fibroproliferative diseases and organ-specific fibrotic disorders.
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Affiliation(s)
- Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Gregory Mennecier
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Joost Willebrords
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Tereza Cristina Da Silva
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Sara Crespo-Yanguas
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Maria Lúcia Zaidan Dagli
- Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-Cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
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30
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Abstract
The different types of cells in the lung, from the conducting airway epithelium to the alveolar epithelium and the pulmonary vasculature, are interconnected by gap junctions. The specific profile of gap junction proteins, the connexins, expressed in these different cell types forms compartments of intercellular communication that can be further shaped by the release of extracellular nucleotides via pannexin1 channels. In this review, we focus on the physiology of connexins and pannexins and describe how this lung communication network modulates lung function and host defenses in conductive and respiratory airways.
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Affiliation(s)
- Davide Losa
- Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland
- The ithree Institute, University of Technology Sydney, 2007 Ultimo, NSW Australia
| | - Marc Chanson
- Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland
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31
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Xie CR, Sun H, Wang FQ, Li Z, Yin YR, Fang QL, Sun Y, Zhao WX, Zhang S, Zhao WX, Wang XM, Yin ZY. Integrated analysis of gene expression and DNA methylation changes induced by hepatocyte growth factor in human hepatocytes. Mol Med Rep 2015; 12:4250-4258. [PMID: 26099202 PMCID: PMC4526041 DOI: 10.3892/mmr.2015.3974] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 05/08/2015] [Indexed: 12/31/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the one of most common malignant tumors. The tumor microenvironment has a role in not only supporting growth and survival of tumor cells, but also triggering tumor recurrence and metastasis. Hepatocyte growth factor (HGF), one of the important growth factors in the tumor microenvironment, has an important role in angiogenesis, tumorigenesis and regeneration. However, the exact mechanism by which HGF regulates HCC initiation and development via epigenetic reprogramming has remained elusive. The present study focused on the epigenetic modification and target tumor-suppressive genes of HGF treatment in HCC. Expression profiling and DNA methylation array were performed to investigate the function of HGF and examine global genomic DNA methylation changes, respectively. Integrated analysis of gene expression and DNA methylation revealed potential tumor suppressor genes (TSGs) in HCC. The present study showed the multiple functions of HGF in tumorous and nontumorous pathways and global genomic DNA methylation changes. HGF treatment upregulated the expression of DNA methyltransferase 1 (DNMT1). Overexpression of DNMT1 in HCC patients correlated with the malignant potential and poor prognosis of HCC. Furthermore, integration analysis of gene expression and DNA methylation changes revealed novel potential tumor suppressor genes TSGs including MYOCD, PANX2 and LHX9. The present study has provided mechanistic insight into epigenetic repression of TSGs through HGF-induced DNA hypermethylation.
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Affiliation(s)
- Cheng-Rong Xie
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Hongguang Sun
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Fu-Qiang Wang
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Zhao Li
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Yi-Rui Yin
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Qin-Liang Fang
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Yu Sun
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Wen-Xiu Zhao
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Sheng Zhang
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Wen-Xing Zhao
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Xiao-Min Wang
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
| | - Zhen-Yu Yin
- Department of Hepatobiliary Surgery, Zhongshan Hospital, Xiamen University, Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen, Fujian 361004, P.R. China
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32
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Diezmos EF, Sandow SL, Perera DS, King DW, Bertrand PP, Liu L. Pannexin-2 is expressed in the human colon with extensive localization in the enteric nervous system. Neurogastroenterol Motil 2015; 27:672-83. [PMID: 25773474 DOI: 10.1111/nmo.12541] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/16/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND Pannexin-2 (Panx2) is a member of the novel group of membrane spanning protein channels present in the central nervous system. Limited studies have examined Panx2 in the intestine, where it may have important physiological roles. The present study characterized Panx2 expression and localization in the human colon in health and disease states. METHODS Immunofluorescence determined Panx2 localization and co-localization, and quantitative real-time PCR and Western blot determined gene and protein expression in ulcerative colitis (UC), Crohn's disease (CD), and control human colon. KEY RESULTS Panx2 was widely expressed in myenteric and submucosal ganglia, particularly in the cytoplasm of neurons. Panx2 was also expressed on smooth muscle of the muscularis and blood vessels, some non-lymphoid leukocytes, mast cells, and mucosal epithelial cells. Co-localization of Panx2 occurred with β-tubulin, neuronal nitric oxide synthase, substance P, vesicular acetylcholine transporter, and calcitonin gene-related peptide, indicating widespread Panx2 expression in extrinsic and intrinsic neurons. Molecular studies revealed a 3.4-fold higher level of Panx2 mRNA in ascending compared to sigmoid muscularis (p < 0.05), despite similar protein levels. Similarly, UC muscularis showed a 35-fold up-regulation in Panx2 mRNA, but not in protein (p < 0.05). CONCLUSIONS & INFERENCES Here, we demonstrated the dense expression of Panx2 in the enteric nervous system and the co-localization of Panx2 with a spectrum of neuronal markers, indicating that Panx2 may be involved in mediating neurotransmission in the colon. The substantial increase in Panx2 mRNA in UC muscle but not protein suggests that the Panx2 translation process may be disrupted in UC.
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Affiliation(s)
- E F Diezmos
- School of Medical Sciences, UNSW Australia, Sydney, NSW, Australia
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33
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Boassa D, Nguyen P, Hu J, Ellisman MH, Sosinsky GE. Pannexin2 oligomers localize in the membranes of endosomal vesicles in mammalian cells while Pannexin1 channels traffic to the plasma membrane. Front Cell Neurosci 2015; 8:468. [PMID: 25698922 PMCID: PMC4313697 DOI: 10.3389/fncel.2014.00468] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 12/27/2014] [Indexed: 12/13/2022] Open
Abstract
Pannexin2 (Panx2) is the largest of three members of the pannexin proteins. Pannexins are topologically related to connexins and innexins, but serve different functional roles than forming gap junctions. We previously showed that pannexins form oligomeric channels but unlike connexins and innexins, they form only single membrane channels. High levels of Panx2 mRNA and protein in the Central Nervous System (CNS) have been documented. Whereas Pannexin1 (Panx1) is fairly ubiquitous and Pannexin3 (Panx3) is found in skin and connective tissue, both are fully glycosylated, traffic to the plasma membrane and have functions correlated with extracellular ATP release. Here, we describe trafficking and subcellular localizations of exogenous Panx2 and Panx1 protein expression in MDCK, HeLa, and HEK 293T cells as well as endogenous Panx1 and Panx2 patterns in the CNS. Panx2 was found in intracellular localizations, was partially N-glycosylated, and localizations were non-overlapping with Panx1. Confocal images of hippocampal sections immunolabeled for the astrocytic protein GFAP, Panx1 and Panx2 demonstrated that the two isoforms, Panx1 and Panx2, localized at different subcellular compartments in both astrocytes and neurons. Using recombinant fusions of Panx2 with appended genetic tags developed for correlated light and electron microscopy and then expressed in different cell lines, we determined that Panx2 is localized in the membrane of intracellular vesicles and not in the endoplasmic reticulum as initially indicated by calnexin colocalization experiments. Dual immunofluorescence imaging with protein markers for specific vesicle compartments showed that Panx2 vesicles are early endosomal in origin. In electron tomographic volumes, cross-sections of these vesicles displayed fine structural details and close proximity to actin filaments. Thus, pannexins expressed at different subcellular compartments likely exert distinct functional roles, particularly in the nervous system.
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Affiliation(s)
- Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
| | - Phuong Nguyen
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
| | - Junru Hu
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA ; Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Gina E Sosinsky
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA ; Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
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Aasen T. Connexins: junctional and non-junctional modulators of proliferation. Cell Tissue Res 2014; 360:685-99. [PMID: 25547217 DOI: 10.1007/s00441-014-2078-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Accepted: 11/14/2014] [Indexed: 12/11/2022]
Abstract
Mounting evidence indicates that dysregulation of gap junctions and their structural subunits-connexins-often occurs in, and sometimes causes, a variety of proliferative disorders, including cancer. Connexin-mediated regulation of cell proliferation is complex and may involve modulation of gap junction intercellular communication (GJIC), hemichannel signalling, or gap junction-independent paths. However, the exact mechanisms linking connexins to proliferation remain poorly defined and a number of contradictory studies report both pro- and anti-proliferative effects, effects that often depend on the cell or tissue type or the microenvironment. The present review covers junctional and non-junctional regulation of proliferation by connexins, with a particular emphasis on their association with cancer.
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Affiliation(s)
- Trond Aasen
- Molecular Pathology Group, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain,
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35
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Le Vasseur M, Lelowski J, Bechberger JF, Sin WC, Naus CC. Pannexin 2 protein expression is not restricted to the CNS. Front Cell Neurosci 2014; 8:392. [PMID: 25505382 PMCID: PMC4243559 DOI: 10.3389/fncel.2014.00392] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/03/2014] [Indexed: 11/27/2022] Open
Abstract
Pannexins (Panx) are proteins homologous to the invertebrate gap junction proteins called innexins (Inx) and are traditionally described as transmembrane channels connecting the intracellular and extracellular compartments. Three distinct Panx paralogs (Panx1, Panx2 and Panx3) have been identified in vertebrates but previous reports on Panx expression and functionality focused primarily on Panx1 and Panx3 proteins. Several gene expression studies reported that Panx2 transcript is largely restricted to the central nervous system (CNS) hence suggesting that Panx2 might serve an important role in the CNS. However, the lack of suitable antibodies prevented the creation of a comprehensive map of Panx2 protein expression and Panx2 protein localization profile is currently mostly inferred from the distribution of its transcript. In this study, we characterized novel commercial monoclonal antibodies and surveyed Panx2 expression and distribution at the mRNA and protein level by real-time qPCR, Western blotting and immunofluorescence. Panx2 protein levels were readily detected in every tissue examined, even when transcriptional analysis predicted very low Panx2 protein expression. Furthermore, our results indicate that Panx2 transcriptional activity is a poor predictor of Panx2 protein abundance and does not correlate with Panx2 protein levels. Despite showing disproportionately high transcript levels, the CNS expressed less Panx2 protein than any other tissues analyzed. Additionally, we showed that Panx2 protein does not localize at the plasma membrane like other gap junction proteins but remains confined within cytoplasmic compartments. Overall, our results demonstrate that the endogenous expression of Panx2 protein is not restricted to the CNS and is more ubiquitous than initially predicted.
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Affiliation(s)
- Maxence Le Vasseur
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia Vancouver, BC, Canada
| | - Jonathan Lelowski
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia Vancouver, BC, Canada
| | - John F Bechberger
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia Vancouver, BC, Canada
| | - Wun-Chey Sin
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia Vancouver, BC, Canada
| | - Christian C Naus
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia Vancouver, BC, Canada
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36
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Abstract
In less than a decade, a small family of channel-forming glycoproteins, named pannexins, have captured the interest of many biologists, in large part due to their association with common diseases, ranging from cancers to neuropathies to infectious diseases. Although the pannexin family consists of only three members (Panx1, Panx2 and Panx3), one or more of these pannexins are expressed in virtually every mammalian organ, implicating their potential role in a diverse array of pathophysiologies. Panx1 is the most extensively studied, but features of this pannexin must be cautiously extrapolated to the other pannexins, as for example we now know that Panx2, unlike Panx1, exhibits unique properties such as a tendency to be retained within intracellular compartments. In the present review, we assess the biochemical and channel features of pannexins focusing on the literature which links these unique molecules to over a dozen diseases and syndromes. Although no germ-line mutations in genes encoding pannexins have been linked to any diseases, many cases have shown that high pannexin expression is associated with disease onset and/or progression. Disease may also occur, however, when pannexins are underexpressed, highlighting that pannexin expression must be exquisitely regulated. Finally, we discuss some of the most pressing questions and controversies in the pannexin field as the community seeks to uncover the full biological relevance of pannexins in healthy organs and during disease.
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Langlois S, Xiang X, Young K, Cowan BJ, Penuela S, Cowan KN. Pannexin 1 and pannexin 3 channels regulate skeletal muscle myoblast proliferation and differentiation. J Biol Chem 2014; 289:30717-30731. [PMID: 25239622 PMCID: PMC4215249 DOI: 10.1074/jbc.m114.572131] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Pannexins constitute a family of three glycoproteins (Panx1, -2, and -3) forming single membrane channels. Recent work demonstrated that Panx1 is expressed in skeletal muscle and involved in the potentiation of contraction. However, Panxs functions in skeletal muscle cell differentiation, and proliferation had yet to be assessed. We show here that Panx1 and Panx3, but not Panx2, are present in human and rodent skeletal muscle, and their various species are differentially expressed in fetal versus adult human skeletal muscle tissue. Panx1 levels were very low in undifferentiated human primary skeletal muscle cells and myoblasts (HSMM) but increased drastically during differentiation and became the main Panx expressed in differentiated cells. Using HSMM, we found that Panx1 expression promotes this process, whereas it was impaired in the presence of probenecid or carbenoxolone. As for Panx3, its lower molecular weight species were prominent in adult skeletal muscle but very low in the fetal tissue and in undifferentiated skeletal muscle cells and myoblasts. Its overexpression (∼43-kDa species) induced HSMM differentiation and also inhibited their proliferation. On the other hand, a ∼70-kDa immunoreactive species of Panx3, likely glycosylated, sialylated, and phosphorylated, was highly expressed in proliferative myoblasts but strikingly down-regulated during their differentiation. Reduction of its endogenous expression using two Panx3 shRNAs significantly inhibited HSMM proliferation without triggering their differentiation. In summary, our results demonstrate that Panx1 and Panx3 are co-expressed in human skeletal muscle myoblasts and play a pivotal role in dictating the proliferation and differentiation status of these cells.
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Affiliation(s)
- Stéphanie Langlois
- Department of Surgery, Division of Paediatric Surgery, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada,; Apoptosis Research Center, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada
| | - Xiao Xiang
- Apoptosis Research Center, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada,; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada
| | - Kelsey Young
- Apoptosis Research Center, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada
| | - Bryce J Cowan
- Department of Dermatology and Skin Science, University of British Columbia, Vancouver, British Columbia V5Z 4E8, Canada, and
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Kyle N Cowan
- Department of Surgery, Division of Paediatric Surgery, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada,; Apoptosis Research Center, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada,; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada,.
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Schalper KA, Carvajal-Hausdorf D, Oyarzo MP. Possible role of hemichannels in cancer. Front Physiol 2014; 5:237. [PMID: 25018732 PMCID: PMC4073485 DOI: 10.3389/fphys.2014.00237] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022] Open
Abstract
In humans, connexins (Cxs) and pannexins (Panxs) are the building blocks of hemichannels. These proteins are frequently altered in neoplastic cells and have traditionally been considered as tumor suppressors. Alteration of Cxs and Panxs in cancer cells can be due to genetic, epigenetic and post-transcriptional/post-translational events. Activated hemichannels mediate the diffusional membrane transport of ions and small signaling molecules. In the last decade hemichannels have been shown to participate in diverse cell processes including the modulation of cell proliferation and survival. However, their possible role in tumor growth and expansion remains largely unexplored. Herein, we hypothesize about the possible role of hemichannels in carcinogenesis and tumor progression. To support this theory, we summarize the evidence regarding the involvement of hemichannels in cell proliferation and migration, as well as their possible role in the anti-tumor immune responses. In addition, we discuss the evidence linking hemichannels with cancer in diverse models and comment on the current technical limitations for their study.
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Affiliation(s)
- Kurt A Schalper
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile ; Department of Pathology, Yale School of Medicine New Haven, CT, USA
| | | | - Mauricio P Oyarzo
- Servicio Anatomía Patológica, Clínica Alemana de Santiago, Facultad de Medicina Clinica Alemana Universidad del Desarrollo Santiago, Chile
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Abstract
The pannexins (Panxs) are a family of chordate proteins homologous to the invertebrate gap junction forming proteins named innexins. Three distinct Panx paralogs (Panx1, Panx2, and Panx3) are shared among the major vertebrate phyla, but they appear to have suppressed (or even lost) their ability to directly couple adjacent cells. Connecting the intracellular and extracellular compartments is now widely accepted as Panx's primary function, facilitating the passive movement of ions and small molecules along electrochemical gradients. The tissue distribution of the Panxs ranges from pervasive to very restricted, depending on the paralog, and are often cell type-specific and/or developmentally regulated within any given tissue. In recent years, Panxs have been implicated in an assortment of physiological and pathophysiological processes, particularly with respect to ATP signaling and inflammation, and they are now considered to be a major player in extracellular purinergic communication. The following is a comprehensive review of the Panx literature, exploring the historical events leading up to their discovery, outlining our current understanding of their biochemistry, and describing the importance of these proteins in health and disease.
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Affiliation(s)
- Stephen R Bond
- Genome Technology Branch, Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health Bethesda, MD, USA ; Department of Cellular and Physiological Science, Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
| | - Christian C Naus
- Department of Cellular and Physiological Science, Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
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Penuela S, Simek J, Thompson RJ. Regulation of pannexin channels by post-translational modifications. FEBS Lett 2014; 588:1411-5. [PMID: 24486011 DOI: 10.1016/j.febslet.2014.01.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/16/2014] [Accepted: 01/19/2014] [Indexed: 01/25/2023]
Abstract
The large-pore channels formed by the pannexin family of proteins have been implicated in many physiological and pathophysiological functions, mainly through their ATP release function. However, a tight regulation of channel opening is necessary to modulate their function in vivo. Post-translational modifications have been postulated as some of the regulating mechanisms for Panx1, while Panx2 and Panx3 have not been as well characterized. Positive regulators include caspase cleavage to open Panx1 channels in apoptotic cells, and activation by Src family kinases via ionotropic receptors in neurons and macrophages. S-nitrosylation of cysteines has been shown to both inhibit and activate the Panx1 channel in different cell types. All three pannexins are N-glycosylated but to different levels of modification. Their diverse glycosylation appears to regulate cellular localization, intermixing, and may restrict their ability to function as inter-cellular channels. It is clear that our understanding of pannexin post-translational modification and their role in channel function regulation is still in its infancy even a decade after their discovery.
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Affiliation(s)
- Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A5C1, Canada.
| | - Jamie Simek
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A5C1, Canada
| | - Roger J Thompson
- Hotchkiss Brain Institute and Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB T2N 4N1, Canada
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Wicki-Stordeur LE, Swayne LA. The emerging Pannexin 1 signalome: a new nexus revealed? Front Cell Neurosci 2014; 7:287. [PMID: 24409119 PMCID: PMC3884145 DOI: 10.3389/fncel.2013.00287] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 12/23/2013] [Indexed: 11/22/2022] Open
Abstract
Pannexins (Panxs) are a family of single-membrane, large-pore ion, and metabolite permeable channels. Of the three Panx proteins, Panx1 has been most extensively studied, and has recently emerged as an exciting, clinically relevant target in many physiological and pathophysiological settings. This channel is widely expressed across various cell and tissue types; however its links to precise signaling pathways are largely unknown. Here we review the current literature surrounding presently identified Panx1–protein interactions, a critical first step to unraveling the Panx1 signalome. First we elucidate the reported associations of Panx1 with other ion channels, receptors, and channel signaling complexes. Further, we highlight recently identified Panx1–cytoskeleton interactions. Finally, we discuss the implications of these protein–protein interactions for Panx1 function in various cell and tissue types, and identify key outstanding questions arising from this work.
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Affiliation(s)
| | - Leigh A Swayne
- Division of Medical Sciences, University of Victoria Victoria, BC, Canada ; Department of Biology, University of Victoria Victoria, BC, Canada ; Department of Biochemistry and Microbiology, University of Victoria Victoria, BC, Canada ; Department of Cellular and Physiological Sciences and Island Medical Program, University of British Columbia Vancouver, BC, Canada
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Boyce AKJ, Prager RT, Wicki-Stordeur LE, Swayne LA. Pore positioning: current concepts in Pannexin channel trafficking. Channels (Austin) 2013; 8:110-7. [PMID: 24300303 DOI: 10.4161/chan.27287] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pannexins (Panxs) are a multifaceted family of ion and metabolite channels that play key roles in a number of physiological and pathophysiological settings. These single membrane large-pore channels exhibit a variety of tissue, cell type, and subcellular distributions. The lifecycles of Panxs are complex, yet must be understood to accurately target these proteins for future therapeutic use. Here we review the basics of Panx function and localization, and then analyze the recent advances in knowledge regarding Panx trafficking. We examine several intrinsic features of Panxs including specific post-translational modifications, the divergent C-termini, and oligomerization, all of which contribute to Panx anterograde transport pathways. Further, we examine the potential influence of extrinsic factors, such as protein-protein interactions, on Panx trafficking. Finally, we highlight what is currently known with respect to Panx internalization and retrograde transport, and present new data illustrating Panx1 internalization following an activating stimulus.
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Affiliation(s)
- Andrew K J Boyce
- Division of Medical Sciences; Island Medical Program; University of Victoria; Victoria, British Columbia, Canada
| | - Ross T Prager
- Division of Medical Sciences; Island Medical Program; University of Victoria; Victoria, British Columbia, Canada
| | - Leigh E Wicki-Stordeur
- Division of Medical Sciences; Island Medical Program; University of Victoria; Victoria, British Columbia, Canada
| | - Leigh Anne Swayne
- Division of Medical Sciences; Island Medical Program; University of Victoria; Victoria, British Columbia, Canada; Department of Biology; University of Victoria; Victoria, British Columbia, Canada; Department of Biochemistry and Microbiology; University of Victoria; Victoria, British Columbia, Canada; Department of Cellular and Physiological Sciences; University of British Columbia; Vancouver, British Columbia, Canada
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Wicki-Stordeur LE, Boyce AKJ, Swayne LA. Analysis of a pannexin 2-pannexin 1 chimeric protein supports divergent roles for pannexin C-termini in cellular localization. ACTA ACUST UNITED AC 2013; 20:73-9. [PMID: 23659289 DOI: 10.3109/15419061.2013.791681] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Pannexins (Panxs) are a three-member family of large pore ion channels permeable to ions and small molecules. Recent elegant work has demonstrated that the Panx1 C-terminus plays an important role in channel trafficking. Panx2, another family member, has a longer and highly dissimilar C-terminus. Interestingly, Panx1 is readily found at the plasma membrane, while Panx2 is mainly present on intracellular membranes. Here we used overlap-extension cloning to create the first chimeric Panx, consisting of Panx2 with the Panx1 C-terminus (Panx2(Panx1CT)), to determine whether the Panx1 C-terminus influences the trafficking of Panx2. We are the first to observe a high level of co-localization between Panx2 and the endolysosomal enriched mannose-6-phosphate receptor. Interestingly this distinct localization of Panx2 is altered by the presence of the Panx1 C-terminus. These novel observations support previous data indicating the importance of the C-terminus in the control of Panx trafficking, and highlight the complexity of molecular signals involved.
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Affiliation(s)
- Leigh E Wicki-Stordeur
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
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44
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Sampath P. miR-138: a prosurvival oncomiR for glioma stem cells and its therapeutic implications. FUTURE NEUROLOGY 2013. [DOI: 10.2217/fnl.13.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Prabha Sampath
- Institute of Medical Biology, A*Star, 8A Biomedical Grove, 05-41 Immunos, 138648 Singapore
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45
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Cowan KN, Langlois S, Penuela S, Cowan BJ, Laird DW. Pannexin1 and Pannexin3 exhibit distinct localization patterns in human skin appendages and are regulated during keratinocyte differentiation and carcinogenesis. ACTA ACUST UNITED AC 2012; 19:45-53. [PMID: 22947051 DOI: 10.3109/15419061.2012.712575] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Having shown that Panx1 and Panx3 are expressed in the epidermis, we investigated their distribution in human skin adnexal structures and skin cancer. Both proteins were found in hair follicles, sebaceous and eccrine glands, as well as blood vessels. Panx1 was detected as punctate or diffuse intracellular labeling, while Panx3 was only observed as diffuse intracellular staining, suggesting different functions. We also identified the Panx3 immunoreactive ~70 kD species modulated during keratinocyte differentiation as Panx3. Since our data indicate that pannexins are regulated during keratinocyte differentiation, we assessed whether their levels are altered under circumstances in which keratinocyte differentiation is compromised. We found that Panx1 and Panx3 levels are highly reduced in human keratinocyte tumors, thus showing for the first time that both pannexins are dysregulated in human cancers. Altogether, these data suggest that Panx1 and Panx3 have distinct and unique functions within the skin in health and disease.
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Affiliation(s)
- Kyle N Cowan
- Division of Pediatric Surgery, Department of Surgery, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Canada.
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46
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Bond SR, Wang N, Leybaert L, Naus CC. Pannexin 1 Ohnologs in the Teleost Lineage. J Membr Biol 2012; 245:483-93. [DOI: 10.1007/s00232-012-9497-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 07/31/2012] [Indexed: 02/04/2023]
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47
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Chan XHD, Nama S, Gopal F, Rizk P, Ramasamy S, Sundaram G, Ow GS, Ivshina AV, Tanavde V, Haybaeck J, Kuznetsov V, Sampath P. Targeting glioma stem cells by functional inhibition of a prosurvival oncomiR-138 in malignant gliomas. Cell Rep 2012; 2:591-602. [PMID: 22921398 DOI: 10.1016/j.celrep.2012.07.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 02/02/2012] [Accepted: 07/27/2012] [Indexed: 10/28/2022] Open
Abstract
Malignant gliomas are the most aggressive forms of brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a subpopulation of tumor-initiating glioma stem cells (GSCs) that are intrinsically resistant to therapy. Initiation and progression of gliomas have been linked to alterations in microRNA expression. Here, we report the identification of microRNA-138 (miR-138) as a molecular signature of GSCs and demonstrate a vital role for miR-138 in promoting growth and survival of bona fide tumor-initiating cells with self-renewal potential. Sequence-specific functional inhibition of miR-138 prevents tumorsphere formation in vitro and impedes tumorigenesis in vivo. We delineate the components of the miR-138 regulatory network by loss-of-function analysis to identify specific regulators of apoptosis. Finally, the higher expression of miR-138 in GSCs compared to non-neoplastic tissue and association with tumor recurrence and survival highlights the clinical significance of miR-138 as a prognostic biomarker and a therapeutic target for treatment of malignant gliomas.
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Affiliation(s)
- Xin Hui Derryn Chan
- Institute of Medical Biology, Agency for Science Technology and Research, Singapore 138648, Singapore
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Penuela S, Gyenis L, Ablack A, Churko JM, Berger AC, Litchfield DW, Lewis JD, Laird DW. Loss of pannexin 1 attenuates melanoma progression by reversion to a melanocytic phenotype. J Biol Chem 2012; 287:29184-93. [PMID: 22753409 DOI: 10.1074/jbc.m112.377176] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pannexin 1 (Panx1) is a channel-forming glycoprotein expressed in different cell types of mammalian skin. We examined the role of Panx1 in melanoma tumorigenesis and metastasis since qPCR and Western blots revealed that mouse melanocytes exhibited low levels of Panx1 while increased Panx1 expression was correlated with tumor cell aggressiveness in the isogenic melanoma cell lines (B16-F0, -F10, and -BL6). Panx1 shRNA knockdown (Panx1-KD) generated stable BL6 cell lines, with reduced dye uptake, that showed a marked increase in melanocyte-like cell characteristics including higher melanin production, decreased cell migration and enhanced formation of cellular projections. Western blotting and proteomic analyses using 2D-gel/mass spectroscopy identified vimentin and β-catenin as two of the markers of malignant melanoma that were down-regulated in Panx1-KD cells. Xenograft Panx1-KD cells grown within the chorioallantoic membrane of avian embryos developed tumors that were significantly smaller than controls. Mouse-Alu qPCR of the excised avian embryonic organs revealed that tumor metastasis to the liver was significantly reduced upon Panx1 knockdown. These data suggest that while Panx1 is present in skin melanocytes it is up-regulated during melanoma tumor progression, and tumorigenesis can be inhibited by the knockdown of Panx1 raising the possibility that Panx1 may be a viable target for the treatment of melanoma.
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Affiliation(s)
- Silvia Penuela
- Department of Anatomy and Cell BiologyUniversity of Western Ontario, London, Ontario N6A-5C1, Canada
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Gap junction proteins on the move: connexins, the cytoskeleton and migration. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:94-108. [PMID: 22613178 DOI: 10.1016/j.bbamem.2012.05.014] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/25/2012] [Accepted: 05/04/2012] [Indexed: 01/08/2023]
Abstract
Connexin43 (Cx43) has roles in cell-cell communication as well as channel independent roles in regulating motility and migration. Loss of function approaches to decrease Cx43 protein levels in neural cells result in reduced migration of neurons during cortical development in mice and impaired glioma tumor cell migration. In other cell types, correlations between Cx43 expression and cell morphology, adhesion, motility and migration have been noted. In this review we will discuss the common themes that have been revealed by a detailed comparison of the published results of neuronal cells with that of other cell types. In brief, these comparisons clearly show differences in the stability and directionality of protrusions, polarity of movement, and migration, depending on whether a) residual Cx43 levels remain after siRNA or shRNA knockdown, b) Cx43 protein levels are not detectable as in cells from Cx43(-/-) knockout mice or in cells that normally have no endogenous Cx43 expression, c) gain-of-function approaches are used to express Cx43 in cells that have no endogenous Cx43 and, d) Cx43 is over-expressed in cells that already have low endogenous Cx43 protein levels. What is clear from our comparisons is that Cx43 expression influences the adhesiveness of cells and the directionality of cellular processes. These observations are discussed in light of the ability of cells to rearrange their cytoskeleton and move in an organized manner. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
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