101
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Jin Y, Zhou TY, Cao JN, Feng QT, Fu YJ, Xu X, Yang CJ. MicroRNA-206 Downregulates Connexin43 in Cardiomyocytes to Induce Cardiac Arrhythmias in a Transgenic Mouse Model. Heart Lung Circ 2018; 28:1755-1761. [PMID: 30322759 DOI: 10.1016/j.hlc.2018.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/05/2018] [Accepted: 09/18/2018] [Indexed: 01/05/2023]
Abstract
BACKGROUND MicroRNAs (miRNAs) are critical modulators of various physiological and pathological processes, but their role in cardiac arrhythmias remains yet to be completely understood. Connexin43 (Cx43) is an important cardiac gap junction protein and a potential target of miR-206, and downregulation of Cx43 induces ventricular tachyarrhythmias. METHODS We investigated the effects of miR-206 overexpression on the adult mouse heart and in cardiac arrhythmias. Luciferase activity assay was employed to validate Cx43 as a direct target of miR-206. Expression of Cx43 was measured in cardiac muscle cell line HL-1 securely expressing miR-206. An inducible miR-206 overexpression mouse model was established to evaluate the in vivo effect of miR-206 on Cx43 expression and cardiac rhythm. RESULTS MiR-206 directly recognised 3'-untranslated region of Cx43 mRNA to inhibit its expression in HL-1 cells. Induction of miR-206 in the adult mouse heart suppressed Cx43 expression, particularly in the atria and ventricle. Importantly, miR-206 overexpression also induced abnormal heart-rate and PR interval, and shortened life-span in the experimental mice. CONCLUSIONS In cardiomyocytes, miR-206 is a upstream regulator of Cx43, and its overexpression downregulates Cx43 to induce abnormal heart-rate and PR interval.
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Affiliation(s)
- Yan Jin
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Tian-Yi Zhou
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Jia-Ning Cao
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Qiu-Ting Feng
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Ya-Jing Fu
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Xin Xu
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China.
| | - Cheng-Jian Yang
- Department of Cardiology, The Affiliated Wuxi No.2 People's Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China.
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102
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Coronel-Cruz C, Sánchez I, Hernández-Tellez B, Rodríguez-Mata V, Pinzón-Estrada E, Castell-Rodríguez A, Pérez-Armendariz E. Connexin 30.2 is expressed in exocrine vascular endothelial and ductal epithelial cells throughout pancreatic postnatal development. Acta Histochem 2018; 120:558-565. [PMID: 30100173 DOI: 10.1016/j.acthis.2018.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 06/10/2018] [Accepted: 06/29/2018] [Indexed: 02/08/2023]
Abstract
Previously we have demonstrated that the GJ protein connexin 30.2 (Cx30.2) is expressed in pancreatic beta cells and endothelial cells (ECs) of the islet. In the present study, we address whether Cx30.2 is expressed in the exocrine pancreas, including its vascular system. For this, adult mouse pancreatic sections were double labeled with specific antibodies against Cx30.2 and CD31, an endothelial cell marker, or with anti-α-actin smooth muscle, a smooth muscle cell (SMC) marker or anti-mucin-1, a marker of epithelial ductal cells, using immunofluorescence (IF) studies. Cx30.2-IF hot spots were found at junctional membranes of exocrine ECs and SMCs of blood vessels. Furthermore, Cx30.2 was localized in mucin-1 positive cells or epithelial ductal cells. Using immunohistochemistry (IHC) studies, it was found that in vessels and ducts of different diameters, Cx30.2 was also expressed in these cell types. In addition, it was found that Cx30.2 is already expressed in these cell types in pancreatic sections of 3, 14 and 21 days postpartum. Moreover, this cell specific pattern of expression was also found in the adult rat, hamster and guinea pig pancreas. Expression of Cx30.2 mRNA and protein in the pancreas of all these species was confirmed by RT-PCR and Western blot studies. Overall, our results suggest that intercellular coupling mediated by Cx30.2 intercellular channels may synchronize the functional activity of ECs and SMCs of vascular cells, as well as of epithelial ductal cells after birth.
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103
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Choi EJ, Yeo JH, Yoon SM, Lee J. Gambogic Acid and Its Analogs Inhibit Gap Junctional Intercellular Communication. Front Pharmacol 2018; 9:814. [PMID: 30104974 PMCID: PMC6077758 DOI: 10.3389/fphar.2018.00814] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/09/2018] [Indexed: 11/21/2022] Open
Abstract
Gap junctions (GJs) are intercellular channels composed of connexins. Cellular molecules smaller than 1 kDa can diffuse through GJs by a process termed gap junctional intercellular communication (GJIC), which plays essential roles in various pathological and physiological conditions. Gambogic acid (GA), a major component of a natural yellow dye, has been used as traditional medicine and has been reported to have various therapeutic effects, including an anti-cancer effect. In this study, two different GJ assay methods showed that GA and its analogs inhibited GJIC. The inhibition was rapidly reversible and was not mediated by changes in surface expression or S368 phosphorylation of Cx43, cellular calcium concentration, or redox state. We also developed an assay system to measure the intercellular communication induced by Cx40, Cx30, and Cx43. Dihydrogambogic acid (D-GA) potently inhibited GJIC by Cx40 (IC50 = 5.1 μM), whereas the IC50 value of carbenoxolone, which is known as a broad spectrum GJIC inhibitor, was 105.2 μM. Thus, D-GA can act as a pharmacological tool for the inhibition of Cx40.
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Affiliation(s)
- Eun J Choi
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Joo H Yeo
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Sei M Yoon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea.,Department of Integrated OMICS for Biomedical Sciences, Yonsei University, Seoul, South Korea
| | - Jinu Lee
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
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104
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Basheer WA, Shaw RM. Connexin 43 and CaV1.2 Ion Channel Trafficking in Healthy and Diseased Myocardium. Circ Arrhythm Electrophysiol 2018; 9:e001357. [PMID: 27266274 DOI: 10.1161/circep.115.001357] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/29/2016] [Indexed: 11/16/2022]
Affiliation(s)
- Wassim A Basheer
- From the Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA (W.A.B., R.M.S.); and Department of Medicine, University of California Los Angeles (R.M.S.)
| | - Robin M Shaw
- From the Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA (W.A.B., R.M.S.); and Department of Medicine, University of California Los Angeles (R.M.S.).
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105
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Taşdelen E, Durmaz CD, Karabulut HG. Autosomal Recessive Oculodentodigital Dysplasia: A Case Report and Review of the Literature. Cytogenet Genome Res 2018; 154:181-186. [PMID: 29902798 DOI: 10.1159/000489000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2018] [Indexed: 11/19/2022] Open
Abstract
Oculodentodigital dysplasia (ODDD) is a rare condition characterized by a typical facial appearance and variable findings of the eyes, teeth, and fingers. ODDD is caused by mutations in the GJA1 gene in chromosome 6q22 and inherited in an autosomal dominant manner in the majority of the patients. However, in recent clinical reports, autosomal recessive ODDD cases due to by GJA1 mutations were also described. Here, we report on a 14-year-old boy with microphthalmia, microcornea, narrow nasal bridge, hypoplastic alae nasi, prominent columnella, hypodontia, dental caries, and partial syndactyly of the 2nd and 3rd toes. These clinical findings were concordant with the diagnosis of ODDD, and a novel homozygous mutation (c.442C>T, p.Arg148Ter) was determined in the GJA1 gene leading to a premature stop codon. His phenotypically normal parents were found to be carriers of the same mutation. This is the third family in the literature in which ODDD segregates in an autosomal recessive manner.
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106
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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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107
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Easton JA, Albuloushi AK, Kamps MAF, Brouns GHMR, Broers JLV, Coull BJ, Oji V, van Geel M, van Steensel MAM, Martin PE. A rare missense mutation in GJB3
(Cx31G45E) is associated with a unique cellular phenotype resulting in necrotic cell death. Exp Dermatol 2018; 28:1106-1113. [DOI: 10.1111/exd.13542] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2018] [Indexed: 11/27/2022]
Affiliation(s)
- Jennifer A. Easton
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht The Netherlands
| | - Ahmad K. Albuloushi
- Department of Life Sciences; School of Health and Life Sciences; Glasgow Caledonian University; Glasgow UK
| | - Miriam A. F. Kamps
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht The Netherlands
- Department of Genetics and Cell Biology; Maastricht University; Maastricht The Netherlands
| | - Gladys H. M. R. Brouns
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
| | - Jos L. V. Broers
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht The Netherlands
- Department of Genetics and Cell Biology; Maastricht University; Maastricht The Netherlands
| | - Barry J. Coull
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
- Division of Biological Chemistry and Drug Discovery; College of Life Sciences; University of Dundee; Dundee UK
| | - Vincent Oji
- Department of Dermatology; University Hospital Münster; Münster Germany
| | - Michel van Geel
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht The Netherlands
| | - Maurice A. M. van Steensel
- Department of Dermatology; Maastricht University Medical Centre; Maastricht The Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht The Netherlands
- Skin Research Institute of Singapore; Institute of Medical Biology, Immunos; Singapore
| | - Patricia E. Martin
- Department of Life Sciences; School of Health and Life Sciences; Glasgow Caledonian University; Glasgow UK
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108
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Overexpression of Cx43 in cells of the myocardial scar: Correction of post-infarct arrhythmias through heterotypic cell-cell coupling. Sci Rep 2018; 8:7145. [PMID: 29739982 PMCID: PMC5940892 DOI: 10.1038/s41598-018-25147-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 04/06/2018] [Indexed: 12/16/2022] Open
Abstract
Ventricular tachycardia (VT) is the most common and potentially lethal complication following myocardial infarction (MI). Biological correction of the conduction inhomogeneity that underlies re-entry could be a major advance in infarction therapy. As minimal increases in conduction of infarcted tissue markedly influence VT susceptibility, we reasoned that enhanced propagation of the electrical signal between non-excitable cells within a resolving infarct might comprise a simple means to decrease post-infarction arrhythmia risk. We therefore tested lentivirus-mediated delivery of the gap-junction protein Connexin 43 (Cx43) into acute myocardial lesions. Cx43 was expressed in (myo)fibroblasts and CD45+ cells within the scar and provided prominent and long lasting arrhythmia protection in vivo. Optical mapping of Cx43 injected hearts revealed enhanced conduction velocity within the scar, indicating Cx43-mediated electrical coupling between myocytes and (myo)fibroblasts. Thus, Cx43 gene therapy, by direct in vivo transduction of non-cardiomyocytes, comprises a simple and clinically applicable biological therapy that markedly reduces post-infarction VT.
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109
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Berry V, Ionides ACW, Pontikos N, Moghul I, Moore AT, Cheetham ME, Michaelides M. Whole-genome sequencing reveals a recurrent missense mutation in the Connexin 46 (GJA3) gene causing autosomal-dominant lamellar cataract. Eye (Lond) 2018; 32:1661-1668. [PMID: 29934635 PMCID: PMC6189195 DOI: 10.1038/s41433-018-0154-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/24/2018] [Accepted: 05/03/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Congenital cataract, opacification of the ocular lens, is clinically and genetically a heterogeneous childhood disease. In this study we aimed to identify the underlying genetic cause of isolated autosomal-dominant lamellar cataract in a multi-generation English family. METHODS Whole-genome sequencing (WGS) was undertaken in two affected subjects and one unaffected individual. Segregation analysis was performed and a known cataract-causing mutation was identified. Segregation was further validated by sanger sequencing in the entire pedigree. RESULTS A heterozygous mutation c.7 G > T; p.D3Y was identified in an NH2-terminal region of the gap junction protein GJA3 and found to co-segregate with disease. CONCLUSION We have identified a recurrent mutation in GJA3 in a large British pedigree causing the novel phenotype of autosomal-dominant congenital lamellar cataract. Previously, p.D3Y was found in a Hispanic family causing pulverulent cataract. WGS proved an efficient method to find the underlying molecular cause in this large family, which could not be mapped due to uninformative markers.
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Affiliation(s)
- Vanita Berry
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | | | - Nikolas Pontikos
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
- UCL Genetics Institute, University College London, London, WC1E 6BT, UK
| | - Ismail Moghul
- UCL Cancer Institute, University College London, London, WC1E 6DD, UK
| | - Anthony T Moore
- Moorfields Eye Hospital, London, EC1V 2PD, UK
- Ophthalmology Department, University of California School of Medicine, San Francisco, CA, 94158, USA
| | | | - Michel Michaelides
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
- Moorfields Eye Hospital, London, EC1V 2PD, UK.
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110
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Dosch M, Gerber J, Jebbawi F, Beldi G. Mechanisms of ATP Release by Inflammatory Cells. Int J Mol Sci 2018; 19:ijms19041222. [PMID: 29669994 PMCID: PMC5979498 DOI: 10.3390/ijms19041222] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 04/02/2018] [Accepted: 04/05/2018] [Indexed: 02/06/2023] Open
Abstract
Extracellular nucleotides (e.g., ATP, ADP, UTP, UDP) released by inflammatory cells interact with specific purinergic P2 type receptors to modulate their recruitment and activation. The focus of this review is on stimuli and mechanisms of extracellular nucleotide release and its consequences during inflammation. Necrosis leads to non-specific release of nucleotides, whereas specific release mechanisms include vesicular exocytosis and channel-mediated release via connexin or pannexin hemichannels. These release mechanisms allow stimulated inflammatory cells such as macrophages, neutrophils, and endothelial cells to fine-tune autocrine/paracrine responses during acute and chronic inflammation. Key effector functions of inflammatory cells are therefore regulated by purinergic signaling in acute and chronic diseases, making extracellular nucleotide release a promising target for the development of new therapies.
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Affiliation(s)
- Michel Dosch
- Department for Visceral Surgery and Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland.
- Department for BioMedical Research (DBMR), Bern University Hospital, University of Bern, CH-3008 Bern, Switzerland.
| | - Joël Gerber
- Department for Visceral Surgery and Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland.
- Department for BioMedical Research (DBMR), Bern University Hospital, University of Bern, CH-3008 Bern, Switzerland.
| | - Fadi Jebbawi
- Department for Visceral Surgery and Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland.
- Department for BioMedical Research (DBMR), Bern University Hospital, University of Bern, CH-3008 Bern, Switzerland.
| | - Guido Beldi
- Department for Visceral Surgery and Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland.
- Department for BioMedical Research (DBMR), Bern University Hospital, University of Bern, CH-3008 Bern, Switzerland.
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111
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Garcia MA, Nelson WJ, Chavez N. Cell-Cell Junctions Organize Structural and Signaling Networks. Cold Spring Harb Perspect Biol 2018; 10:a029181. [PMID: 28600395 PMCID: PMC5773398 DOI: 10.1101/cshperspect.a029181] [Citation(s) in RCA: 273] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cell-cell junctions link cells to each other in tissues, and regulate tissue homeostasis in critical cell processes that include tissue barrier function, cell proliferation, and migration. Defects in cell-cell junctions give rise to a wide range of tissue abnormalities that disrupt homeostasis and are common in genetic abnormalities and cancers. Here, we discuss the organization and function of cell-cell junctions primarily involved in adhesion (tight junction, adherens junction, and desmosomes) in two different epithelial tissues: a simple epithelium (intestine) and a stratified epithelium (epidermis). Studies in these tissues reveal similarities and differences in the organization and functions of different cell-cell junctions that meet the requirements for the specialized functions of each tissue. We discuss cell-cell junction responses to genetic and environmental perturbations that provide further insights into their roles in maintaining tissue homeostasis.
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Affiliation(s)
- Miguel A Garcia
- Department of Biology, Stanford University, Stanford, California 94305
| | - W James Nelson
- Department of Biology, Stanford University, Stanford, California 94305
- Departments of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305
| | - Natalie Chavez
- Department of Biology, Stanford University, Stanford, California 94305
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112
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Lee KH, Kim NH. Expressional Patterns of Connexin Isoforms in the Rat Epididymal Fat during Postnatal Development. Dev Reprod 2018; 22:29-38. [PMID: 29707682 PMCID: PMC5915765 DOI: 10.12717/dr.2018.22.1.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/10/2018] [Accepted: 03/17/2018] [Indexed: 12/31/2022]
Abstract
In the multicellular tissue, cell-cell interaction is important for a precise
control of its function. The exchange of signaling molecules between adjacent
cells via connexon allows the functional harmony of cells in the tissue. The
present research was to determine the presence and expressional patterns of
connexin (Cx) isoforms in the rat epididymal fat during
postnatal development using quantitative real-time polymerase chain reaction
(PCR) analysis. Of 13 Cx isoforms examined, expression of 11
Cx isoforms in the epididymal fat during postnatal
development was detected. These Cx isoforms include
Cx26, Cx31, Cx31.1,
Cx32, Cx33, Cx36,
Cx37, Cx40, Cx43,
Cx45, and Cx50. Expressional levels of all
Cx isoforms at 1 and 2 years of age were significantly
higher than those at the early postnatal ages, such as 7 days, 14 days, and 24
days of ages. Except Cx33 and Cx43, the
transcript levels of rest Cx isoforms at 1 year of age were
significantly lower than that at 2 years of age. In addition, expressional
patterns of Cx isoforms between 7 days and 5 months of ages
generally varied according to the isoform. The existence of various
Cx isoforms in the rat epididymal fat has been identified
and expression of each Cx isoform in the epididymal fat during
postnatal development has shown a particular pattern, distinguishable from the
others. To our knowledges, this is the first report showing expressional
patterns of Cx isoforms at transcript level in the epididymal
fat at various postnatal ages.
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Affiliation(s)
- Ki-Ho Lee
- Dept. of Biochemistry and Molecular Biology, College of Medicine, Eulji University, Daejeon 34824, Korea
| | - Nan Hee Kim
- Dept. of Biochemistry and Molecular Biology, College of Medicine, Eulji University, Daejeon 34824, Korea
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113
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Shi W, Riquelme MA, Gu S, Jiang JX. Connexin hemichannels mediate glutathione transport and protect lens fiber cells from oxidative stress. J Cell Sci 2018; 131:jcs212506. [PMID: 29487175 PMCID: PMC5897712 DOI: 10.1242/jcs.212506] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/07/2018] [Indexed: 01/04/2023] Open
Abstract
Elevated oxidized stress contributes to lens cataracts, and gap junctions play important roles in maintaining lens transparency. As well as forming gap junctions, connexin (Cx) proteins also form hemichannels. Here, we report a new mechanism whereby hemichannels mediate transport of reductant glutathione into lens fiber cells and protect cells against oxidative stress. We found that Cx50 (also known as GJA8) hemichannels opened in response to H2O2 in lens fiber cells but that transport through the channels was inhibited by two dominant-negative mutants in Cx50, Cx50P88S, which inhibits transport through both gap junctions and hemichannels, and Cx50H156N, which only inhibits transport through hemichannels and not gap junctions. Treatment with H2O2 increased the number of fiber cells undergoing apoptosis, and this increase was augmented with dominant-negative mutants that disrupted both hemichannels formed from Cx46 (also known as GJA3) and Cx50, while Cx50E48K, which only impairs gap junctions, did not have such an effect. Moreover, hemichannels mediate uptake of glutathione, and this uptake protected lens fiber cells against oxidative stress, while hemichannels with impaired transport had less protective benefit from glutathione. Taken together, these results show that oxidative stress activates connexin hemichannels in the lens fiber cells and that hemichannels likely protect lens cell against oxidative damage through transporting extracellular reductants.
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Affiliation(s)
- Wen Shi
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha 410000, China
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
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114
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Expression and function of connexin 43 protein in mouse and human retinal pigment epithelial cells as hemichannels and gap junction proteins. Exp Eye Res 2018; 168:128-137. [DOI: 10.1016/j.exer.2018.01.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 01/08/2023]
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115
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Langhorst H, Jüttner R, Groneberg D, Mohtashamdolatshahi A, Pelz L, Purfürst B, Schmidt-Ott KM, Friebe A, Rathjen FG. The IgCAM CLMP regulates expression of Connexin43 and Connexin45 in intestinal and ureteral smooth muscle contraction in mice. Dis Model Mech 2018; 11:dmm.032128. [PMID: 29361518 PMCID: PMC5894946 DOI: 10.1242/dmm.032128] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 01/09/2018] [Indexed: 11/25/2022] Open
Abstract
CAR-like membrane protein (CLMP), an immunoglobulin cell adhesion molecule (IgCAM), has been implicated in congenital short-bowel syndrome in humans, a condition with high mortality for which there is currently no cure. We therefore studied the function of CLMP in a Clmp-deficient mouse model. Although we found that the levels of mRNAs encoding Connexin43 or Connexin45 were not or were only marginally affected, respectively, by Clmp deficiency, the absence of CLMP caused a severe reduction of both proteins in smooth muscle cells of the intestine and of Connexin43 in the ureter. Analysis of calcium signaling revealed a disordered cell-cell communication between smooth muscle cells, which in turn induced an impaired and uncoordinated motility of the intestine and the ureter. Consequently, insufficient transport of chyme and urine caused a fatal delay to thrive, a high rate of mortality, and provoked a severe hydronephrosis in CLMP knockouts. Neurotransmission and the capability of smooth muscle cells to contract in ring preparations of the intestine were not altered. Physical obstructions were not detectable and an overall normal histology in the intestine as well as in the ureter was observed, except for a slight hypertrophy of smooth muscle layers. Deletion of Clmp did not lead to a reduced length of the intestine as shown for the human CLMP gene but resulted in gut malrotations. In sum, the absence of CLMP caused functional obstructions in the intestinal tract and ureter by impaired peristaltic contractions most likely due to a lack of gap-junctional communication between smooth muscle cells. Summary: The function of the immunoglobulin cell adhesion molecule CLMP was investigated in a mouse model. CLMP is essential for intestinal and ureteral peristalsis, and for expression of Connexin43 and 45 in smooth muscle cells.
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Affiliation(s)
- Hanna Langhorst
- Max-Delbrück-Center for Molecular Medicine, DE-13092 Berlin, Germany
| | - René Jüttner
- Max-Delbrück-Center for Molecular Medicine, DE-13092 Berlin, Germany
| | - Dieter Groneberg
- Physiologisches Institut der Universität Würzburg, Röntgenring 9, DE-97070 Würzburg, Germany
| | | | - Laura Pelz
- Max-Delbrück-Center for Molecular Medicine, DE-13092 Berlin, Germany
| | - Bettina Purfürst
- Max-Delbrück-Center for Molecular Medicine, DE-13092 Berlin, Germany
| | - Kai M Schmidt-Ott
- Charité-Universitätsmedizin Berlin, Department of Nephrology, Charitéplatz 1, DE-10117 Berlin, Germany
| | - Andreas Friebe
- Physiologisches Institut der Universität Würzburg, Röntgenring 9, DE-97070 Würzburg, Germany
| | - Fritz G Rathjen
- Max-Delbrück-Center for Molecular Medicine, DE-13092 Berlin, Germany
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Ezrin-anchored PKA phosphorylates serine 369 and 373 on connexin 43 to enhance gap junction assembly, communication, and cell fusion. Biochem J 2018; 475:455-476. [PMID: 29259079 DOI: 10.1042/bcj20170529] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/25/2022]
Abstract
A limited number of human cells can fuse to form multinucleated syncytia. In the differentiation of human placenta, mononuclear cytotrophoblasts fuse to form an endocrinologically active, non-proliferative, multinucleated syncytium. This syncytium covers the placenta and manages the exchange of nutrients and gases between maternal and fetal circulation. We recently reported protein kinase A (PKA) to be part of a macromolecular signaling complex with ezrin and gap junction protein connexin 43 (Cx43) that provides cAMP-mediated control of gap junction communication. Here, we examined the associated phosphorylation events. Inhibition of PKA activity resulted in decreased Cx43 phosphorylation, which was associated with reduced trophoblast fusion and differentiation. In vitro studies using peptide arrays, together with mass spectrometry, pointed to serine 369 and 373 of Cx43 as the major PKA phosphorylation sites that increases gap junction assembly at the plasmalemma. A combination of knockdown and reconstitution experiments and gap-fluorescence loss in photobleaching assays with mutant Cx43 containing single or double phosphoserine-mimicking amino acid substitutions in putative PKA phosphorylation sites demonstrated that phosphorylation of S369 and S373 mediated gap junction communication, trophoblast differentiation, and cell fusion.
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117
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Agrahari AK, Kumar A, R S, Zayed H, C GPD. Substitution impact of highly conserved arginine residue at position 75 in GJB1 gene in association with X-linked Charcot-Marie-tooth disease: A computational study. J Theor Biol 2018; 437:305-317. [PMID: 29111421 DOI: 10.1016/j.jtbi.2017.10.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/23/2017] [Accepted: 10/26/2017] [Indexed: 10/18/2022]
Abstract
X-linked Charcot-Marie-Tooth type 1 X (CMTX1) disease is a subtype of Charcot-Marie-Tooth (CMT), which is mainly caused by mutations in the GJB1 gene. It is also known as connexin 32 (Cx32) that leads to Schwann cell abnormalities and peripheral neuropathy. CMTX1 is considered as the second most common form of CMT disease. The aim of this study is to computationally predict the potential impact of different single amino acid substitutions at position 75 of Cx32, from arginine (R) to proline (P), glutamine (Q) and tryptophan (W). This position is known to be highly conserved among the family of connexin. To understand the structural and functional changes due to these single amino acid substitutions, we employed a homology-modeling technique to build the three-dimensional structure models for the native and mutant proteins. The protein structures were further embedded into a POPC lipid bilayer, inserted into a water box, and subjected to molecular dynamics simulation for 50 ns. Our results show that the mutants R75P, R75Q and R75W display variable structural conformation and dynamic behavior compared to the native protein. Our data proves useful in predicting the potential pathogenicity of the mutant proteins and is expected to serve as a platform for drug discovery for patients with CMT.
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Affiliation(s)
| | - Amit Kumar
- Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, via Marengo 2, 09123 Cagliari, Italy; Biosciences Sector, Center for advanced study research and development in Sardinia (CRS4), Loc. Piscina Manna, 09010 Pula, Italy
| | - Siva R
- School of Biosciences and Technology, VIT University, Vellore, Tamil Nadu, India
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health and Sciences, Qatar University, Doha, Qatar
| | - George Priya Doss C
- School of Biosciences and Technology, VIT University, Vellore, Tamil Nadu, India.
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Guerrero J, Oliveira H, Aid R, Bareille R, Siadous R, Letourneur D, Mao Y, Kohn J, Amédée J. Influence of the three‐dimensional culture of human bone marrow mesenchymal stromal cells within a macroporous polysaccharides scaffold on Pannexin 1 and Pannexin 3. J Tissue Eng Regen Med 2018; 12:e1936-e1949. [DOI: 10.1002/term.2625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/30/2017] [Accepted: 11/29/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Julien Guerrero
- Inserm, U1026, Tissue BioengineeringUniversity of Bordeaux Bordeaux Cedex France
- Department of BiomedicineUniversity Hospital Basel, University of Basel Basel Switzerland
| | - Hugo Oliveira
- Inserm, U1026, Tissue BioengineeringUniversity of Bordeaux Bordeaux Cedex France
| | - Rachida Aid
- Inserm U1148, LVTS, X. Bichat HospitalUniversity Paris Diderot F‐75018 Paris, Institut Galilée, University Paris 13, 93430 Villetaneuse Paris Cedex 18; University Paris Diderot, CHUX, Bichat Paris France
| | - Reine Bareille
- Inserm, U1026, Tissue BioengineeringUniversity of Bordeaux Bordeaux Cedex France
| | - Robin Siadous
- Inserm, U1026, Tissue BioengineeringUniversity of Bordeaux Bordeaux Cedex France
| | - Didier Letourneur
- Inserm U1148, LVTS, X. Bichat HospitalUniversity Paris Diderot F‐75018 Paris, Institut Galilée, University Paris 13, 93430 Villetaneuse Paris Cedex 18; University Paris Diderot, CHUX, Bichat Paris France
| | - Yong Mao
- The New Jersey Center for Biomaterials, Department of Chemistry and Chemical BiologyRutgers The State University of New Jersey Piscataway NJ USA
| | - Joachim Kohn
- The New Jersey Center for Biomaterials, Department of Chemistry and Chemical BiologyRutgers The State University of New Jersey Piscataway NJ USA
| | - Joëlle Amédée
- Inserm, U1026, Tissue BioengineeringUniversity of Bordeaux Bordeaux Cedex France
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119
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Li S, Bjelobaba I, Stojilkovic SS. Interactions of Pannexin1 channels with purinergic and NMDA receptor channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2018; 1860:166-173. [PMID: 28389204 PMCID: PMC5628093 DOI: 10.1016/j.bbamem.2017.03.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 12/31/2022]
Abstract
Pannexins are a three-member family of vertebrate plasma membrane spanning molecules that have homology to the invertebrate gap junction forming proteins, the innexins. However, pannexins do not form gap junctions but operate as plasma membrane channels. The best-characterized member of these proteins, Pannexin1 (Panx1) was suggested to be functionally associated with purinergic P2X and N-methyl-D-aspartate (NMDA) receptor channels. Activation of these receptor channels by their endogenous ligands leads to cross-activation of Panx1 channels. This in turn potentiates P2X and NMDA receptor channel signaling. Two potentiation concepts have been suggested: enhancement of the current responses and/or sustained receptor channel activation by ATP released through Panx1 pore and adenosine generated by ectonucleotidase-dependent dephosphorylation of ATP. Here we summarize the current knowledge and hypotheses about interactions of Panx1 channels with P2X and NMDA receptor channels. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin 300387, China
| | - Ivana Bjelobaba
- Institute for Biological Research "Sinisa Stankovic", University of Belgrade, 11000 Belgrade, Serbia
| | - Stanko S Stojilkovic
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
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121
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Khadilkar SV, Yadav RS, Patel BA. X-Linked Charcot–Marie–Tooth Disease. Neuromuscul Disord 2018. [DOI: 10.1007/978-981-10-5361-0_39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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122
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Abstract
Connexons form the basis of hemichannels and gap junctions. They are composed of six tetraspan proteins called connexins. Connexons can function as individual hemichannels, releasing cytosolic factors (such as ATP) into the pericellular environment. Alternatively, two hemichannel connexons from neighbouring cells can come together to form gap junctions, membrane-spanning channels that facilitate cell-cell communication by enabling signalling molecules of approximately 1 kDa to pass from one cell to an adjacent cell. Connexins are expressed in joint tissues including bone, cartilage, skeletal muscle and the synovium. Indicative of their importance as gap junction components, connexins are also known as gap junction proteins, but individual connexin proteins are gaining recognition for their channel-independent roles, which include scaffolding and signalling functions. Considerable evidence indicates that connexons contribute to the function of bone and muscle, but less is known about the function of connexons in other joint tissues. However, the implication that connexins and gap junctional channels might be involved in joint disease, including age-related bone loss, osteoarthritis and rheumatoid arthritis, emphasizes the need for further research into these areas and highlights the therapeutic potential of connexins.
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Affiliation(s)
- Henry J Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia 23284, USA
| | - Roy W Qu
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
| | - Damian C Genetos
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
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Vicario N, Zappalà A, Calabrese G, Gulino R, Parenti C, Gulisano M, Parenti R. Connexins in the Central Nervous System: Physiological Traits and Neuroprotective Targets. Front Physiol 2017; 8:1060. [PMID: 29326598 PMCID: PMC5741605 DOI: 10.3389/fphys.2017.01060] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/04/2017] [Indexed: 01/22/2023] Open
Abstract
Cell-to-cell interaction and cell-to-extracellular environment communication are emerging as new therapeutic targets in neurodegenerative disorders. Dynamic expression of connexins leads to distinctive hemichannels and gap junctions, characterized by cell-specific conduction, exchange of stimuli or metabolites, and particular channel functions. Herein, we briefly reviewed classical physiological traits and functions of connexins, hemichannels, and gap junctions, in order to discuss the controversial role of these proteins and their mediated interactions during neuroprotection, with a particular focus on Cx43-based channels. We pointed out the contribution of connexins in neural cells populations during neurodegenerative processes to explore potential neuroprotective therapeutic applications.
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Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Giovanna Calabrese
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Carmela Parenti
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Massimo Gulisano
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.,Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
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124
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Willebrords J, Maes M, Crespo Yanguas S, Vinken M. Inhibitors of connexin and pannexin channels as potential therapeutics. Pharmacol Ther 2017; 180:144-160. [PMID: 28720428 PMCID: PMC5802387 DOI: 10.1016/j.pharmthera.2017.07.001] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
While gap junctions support the exchange of a number of molecules between neighboring cells, connexin hemichannels provide communication between the cytosol and the extracellular environment of an individual cell. The latter equally holds true for channels composed of pannexin proteins, which display an architecture reminiscent of connexin hemichannels. In physiological conditions, gap junctions are usually open, while connexin hemichannels and, to a lesser extent, pannexin channels are typically closed, yet they can be activated by a number of pathological triggers. Several agents are available to inhibit channels built up by connexin and pannexin proteins, including alcoholic substances, glycyrrhetinic acid, anesthetics and fatty acids. These compounds not always strictly distinguish between gap junctions, connexin hemichannels and pannexin channels, and may have effects on other targets as well. An exception lies with mimetic peptides, which reproduce specific amino acid sequences in connexin or pannexin primary protein structure. In this paper, a state-of-the-art overview is provided on inhibitors of cellular channels consisting of connexins and pannexins with specific focus on their mode-of-action and therapeutic potential.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium.
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125
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Direct visualization of interaction between calmodulin and connexin45. Biochem J 2017; 474:4035-4051. [PMID: 28963343 DOI: 10.1042/bcj20170426] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/12/2017] [Accepted: 09/25/2017] [Indexed: 01/21/2023]
Abstract
Calmodulin (CaM) is an intracellular Ca2+ transducer involved in numerous activities in a broad Ca2+ signaling network. Previous studies have suggested that the Ca2+/CaM complex may participate in gap junction regulation via interaction with putative CaM-binding motifs in connexins; however, evidence of direct interactions between CaM and connexins has remained elusive to date due to challenges related to the study of membrane proteins. Here, we report the first direct interaction of CaM with Cx45 (connexin45) of γ-family in living cells under physiological conditions by monitoring bioluminescence resonance energy transfer. The interaction between CaM and Cx45 in cells is strongly dependent on intracellular Ca2+ concentration and can be blocked by the CaM inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7). We further reveal a CaM-binding site at the cytosolic loop (residues 164-186) of Cx45 using a peptide model. The strong binding (Kd ∼ 5 nM) observed between CaM and Cx45 peptide, monitored by fluorescence-labeled CaM, is found to be Ca2+-dependent. Furthermore, high-resolution nuclear magnetic resonance spectroscopy reveals that CaM and Cx45 peptide binding leads to global chemical shift changes of 15N-labeled CaM, but does not alter the size of the structure. Observations involving both N- and C-domains of CaM to interact with the Cx45 peptide differ from the embraced interaction with Cx50 from another connexin family. Such interaction further increases Ca2+ sensitivity of CaM, especially at the N-terminal domain. Results of the present study suggest that both helicity and the interaction mode of the cytosolic loop are likely to contribute to CaM's modulation of connexins.
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126
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Endoplasmic Reticulum Stress in Hearing Loss. JOURNAL OF OTORHINOLARYNGOLOGY, HEARING AND BALANCE MEDICINE 2017. [DOI: 10.3390/ohbm1010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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127
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The Role of Gap Junction-Mediated Endothelial Cell-Cell Interaction in the Crosstalk between Inflammation and Blood Coagulation. Int J Mol Sci 2017; 18:ijms18112254. [PMID: 29077057 PMCID: PMC5713224 DOI: 10.3390/ijms18112254] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/21/2017] [Accepted: 10/24/2017] [Indexed: 12/29/2022] Open
Abstract
Endothelial cells (ECs) play a pivotal role in the crosstalk between blood coagulation and inflammation. Endothelial cellular dysfunction underlies the development of vascular inflammatory diseases. Recent studies have revealed that aberrant gap junctions (GJs) and connexin (Cx) hemichannels participate in the progression of cardiovascular diseases such as cardiac infarction, hypertension and atherosclerosis. ECs can communicate with adjacent ECs, vascular smooth muscle cells, leukocytes and platelets via GJs and Cx channels. ECs dynamically regulate the expression of numerous Cxs, as well as GJ functionality, in the context of inflammation. Alterations to either result in various side effects across a wide range of vascular functions. Here, we review the roles of endothelial GJs and Cx channels in vascular inflammation, blood coagulation and leukocyte adhesion. In addition, we discuss the relevant molecular mechanisms that endothelial GJs and Cx channels regulate, both the endothelial functions and mechanical properties of ECs. A better understanding of these processes promises the possibility of pharmacological treatments for vascular pathogenesis.
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128
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Progesterone Via its Type-A Receptor Promotes Myometrial Gap Junction Coupling. Sci Rep 2017; 7:13357. [PMID: 29042599 PMCID: PMC5645358 DOI: 10.1038/s41598-017-13488-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 09/20/2017] [Indexed: 12/17/2022] Open
Abstract
Effective labour contractions require synchronization of myometrial cells through gap junctions (GJs). Clasically, progesterone (P4) is known to inhibit the expression of connexin-43 (Cx43, major component of GJs) and GJ formation in myometrium. Our current study is based on a striking observation that challenges this dogma. We observed conspicuous differences in the intracellular localization of Cx43 protein in PRA versus PRB expressing myocytes. Thus in P4 stimulated PRA cells Cx43 protein forms GJs, whereas in PRB cells the forward trafficking of Cx43 and GJ formation is inhibited even when Cx43 is overexpressed. We found that P4, via PRA/B, differentially regulates Cx43 translation to generate a Cx43-20 K isoform, which facilitates the transport of full length Cx43 to plasma membrane. The P4 mediated regulation of Cx43 trafficking and GJ formation occurs via non-genomic pathway and involves the regulation of mTOR signaling since inhibition of this pathway restored the Cx43 trafficking defect in PRB cells. We propose that PRA is a master regulator of Cx43 expression, GJ formation and myocyte connectivity/synchronization for labour.
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129
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The Potential Prognostic Value of Connexin 43 Expression in Head and Neck Squamous Cell Carcinomas. Appl Immunohistochem Mol Morphol 2017; 24:476-81. [PMID: 26447893 DOI: 10.1097/pai.0000000000000212] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Gap juctions are transmembrane communication channels known to be involved in the control of cell proliferation by mediating the exchange of ions and small molecules between cells. Gap junctions are composed of connexon hemichannels made up of 6 connexin proteins, which abnormal expression and functions have been linked to tumor progression and poorer prognosis. Here, we studied the prognostic impact of the most prevalent connexin isotype, connexin 43 (Cx43) in head and neck squamous cell carcinomas (HNSCC). Tissue microarrays made from tumor samples of 90 HNSCC patients were immunostained for Cx43 and cell cycle regulation-related biomarkers including p53, Ki67, p16, aurora A, geminin, and p21 proteins. Scoring and histopathologic evaluation were performed in digital slides. A 4-tier scoring distinguishing the percentage of positively stained tumor cells was used including score 1: <5%, score 2: 6% to 20%, score 3: 21% to 60%, and score 4: >60%. For statistics, Kaplan-Meier curves with log-rank tests, Cox-regression, and Pearson χ/Fisher exact tests were used.A significant positive correlation was found between Cx43 expression and disease-specific survival of patients (P=0.004). The rate of p21 protein-positive tumor cells also proved to be a significant positive prognostic marker (P=0.014). Cx43 levels also showed a significant positive correlation with p53 expression (P=0.036). However, there was no statistical association between Cx43 levels and the rest of the markers tested neither with T, N, or M stage.In conclusion, our data suggest that reduced Cx43 expression and low p21 protein levels may have a significant negative impact on HNSCC prognosis.
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130
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Raza A, Ghoshal A, Chockalingam S, Ghosh SS. Connexin-43 enhances tumor suppressing activity of artesunate via gap junction-dependent as well as independent pathways in human breast cancer cells. Sci Rep 2017; 7:7580. [PMID: 28790385 PMCID: PMC5548912 DOI: 10.1038/s41598-017-08058-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 05/26/2017] [Indexed: 12/02/2022] Open
Abstract
The gap junction (GJ) protein connexin-43 (Cx43) is considered as a tumour suppressor protein for its role in reversing the phenotype of the cancer cells. In this study, we exploited the antitumor property of Cx43 in conjunction with the artesunate (ART), a plant-based active anti-malarial compound. The reactive oxygen species (ROS) generated by ART resulted in DNA damage, which in turn led to DNA damage response by activation of DNA damage repair proteins. GJ deficient MCF-7 cells transfected with Cx43 gene showed an increased sensitivity towards dose-dependent ART treatment and required a significantly lower dose of ART to attain its IC50, as compared to parental cells. This would ultimately result in reduced dose-dependent side effects of ART. The Co-culture experiments involving GJ intercellular communication (GJIC) deficient and GJIC enabled cells, established the transfer of ROS to the neighbouring cancer cells not exposed to ART. The ROS accumulated in the ART-treated cells induced the oxidative damage in neighbouring cells, leading to bystander cell death and inhibition of bystander cell proliferation. Thus, our study revealed that expression of Cx43 helped in reducing the dose-dependent cytotoxicity of ART as well as enhanced the bystander apoptosis of the neighbouring cells.
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Affiliation(s)
- Asif Raza
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India
| | - Archita Ghoshal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India
| | - S Chockalingam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India
| | - Siddhartha Sankar Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India.
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India.
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131
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Boucher J, Monvoisin A, Vix J, Mesnil M, Thuringer D, Debiais F, Cronier L. Connexins, important players in the dissemination of prostate cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:202-215. [PMID: 28693897 DOI: 10.1016/j.bbamem.2017.06.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/22/2017] [Accepted: 06/29/2017] [Indexed: 12/25/2022]
Abstract
Over the past 50years, increasing experimental evidences have established that connexins (Cxs) and gap junctional intercellular communication (GJIC) ensure an important role in both the onset and development of cancerous processes. In the present review, we focus on the impact of Cxs and GJIC during the development of prostate cancer (PCa), from the primary growth mainly localized in acinar glands and ducts to the distant metastasis mainly concentrated in bone. As observed in several other types of solid tumours, Cxs and especially Cx43 exhibit an ambivalent role with a tumour suppressor effect in the early stages and, conversely, a rather pro-tumoural profile for most of invasion and dissemination steps to secondary sites. We report here the current knowledge on the function of Cxs during PCa cells migration, cytoskeletal dynamics, proteinases activities and the cross talk with the surrounding stromal cells in the microenvironment of the tumour and the bones. In addition, we discuss the role of Cxs in the bone tropism even if the prostate model is rarely used to study the complete sequence of cancer dissemination compared to breast cancer or melanoma. Even if not yet fully understood, these recent findings on Cxs provide new insights into their molecular mechanisms associated with progression and bone targeted behaviour of PCa. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Jonathan Boucher
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France
| | - Arnaud Monvoisin
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France
| | - Justine Vix
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France; Department of Rheumatology, C.H.U. la Milétrie, Poitiers, France
| | - Marc Mesnil
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France
| | | | - Françoise Debiais
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France; Department of Rheumatology, C.H.U. la Milétrie, Poitiers, France
| | - Laurent Cronier
- Laboratory Signalisation et Transports Ioniques Membranaires (STIM), ERL7368 - CNRS, University of Poitiers, Poitiers, France.
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132
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de Toledo SM, Buonanno M, Harris AL, Azzam EI. Genomic instability induced in distant progeny of bystander cells depends on the connexins expressed in the irradiated cells. Int J Radiat Biol 2017; 93:1182-1194. [DOI: 10.1080/09553002.2017.1334980] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sonia M. de Toledo
- Department of Radiology, RUTGERS New Jersey Medical School Cancer Center, Newark, NJ, USA
| | - Manuela Buonanno
- Department of Radiology, RUTGERS New Jersey Medical School Cancer Center, Newark, NJ, USA
| | - Andrew L. Harris
- Pharmacology and Physiology and Neuroscience, RUTGERS New Jersey Medical School Cancer Center, Newark, NJ, USA
| | - Edouard I. Azzam
- Department of Radiology, RUTGERS New Jersey Medical School Cancer Center, Newark, NJ, USA
- Pharmacology and Physiology and Neuroscience, RUTGERS New Jersey Medical School Cancer Center, Newark, NJ, USA
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133
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Multiple and complex influences of connexins and pannexins on cell death. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017. [PMID: 28625689 DOI: 10.1016/j.bbamem.2017.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cell death is a fundamental process for organogenesis, immunity and cell renewal. During the last decades a broad range of molecular tools were identified as important players for several different cell death pathways (apoptosis, pyroptosis, necrosis, autosis…). Aside from these direct regulators of cell death programs, several lines of evidence proposed connexins and pannexins as potent effectors of cell death. In the present review we discussed the potential roles played by connexins, pannexins and innexins in the different cell death programs at different scales from gap junction intercellular communication to protein-protein interactions. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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134
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Epifantseva I, Shaw RM. Intracellular trafficking pathways of Cx43 gap junction channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:40-47. [PMID: 28576298 DOI: 10.1016/j.bbamem.2017.05.018] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 12/11/2022]
Abstract
Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Irina Epifantseva
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Robin M Shaw
- Heart Institute and Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.; Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA..
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135
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Skerrett IM, Williams JB. A structural and functional comparison of gap junction channels composed of connexins and innexins. Dev Neurobiol 2017; 77:522-547. [PMID: 27582044 PMCID: PMC5412853 DOI: 10.1002/dneu.22447] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/12/2016] [Accepted: 08/30/2016] [Indexed: 02/03/2023]
Abstract
Methods such as electron microscopy and electrophysiology led to the understanding that gap junctions were dense arrays of channels connecting the intracellular environments within almost all animal tissues. The characteristics of gap junctions were remarkably similar in preparations from phylogenetically diverse animals such as cnidarians and chordates. Although few studies directly compared them, minor differences were noted between gap junctions of vertebrates and invertebrates. For instance, a slightly wider gap was noted between cells of invertebrates and the spacing between invertebrate channels was generally greater. Connexins were identified as the structural component of vertebrate junctions in the 1980s and innexins as the structural component of pre-chordate junctions in the 1990s. Despite a lack of similarity in gene sequence, connexins and innexins are remarkably similar. Innexins and connexins have the same membrane topology and form intercellular channels that play a variety of tissue- and temporally specific roles. Both protein types oligomerize to form large aqueous channels that allow the passage of ions and small metabolites and are regulated by factors such as pH, calcium, and voltage. Much more is currently known about the structure, function, and structure-function relationships of connexins. However, the innexin field is expanding. Greater knowledge of innexin channels will permit more detailed comparisons with their connexin-based counterparts, and provide insight into the ubiquitous yet specific roles of gap junctions. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 522-547, 2017.
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Affiliation(s)
- I Martha Skerrett
- Biology Department, SUNY Buffalo State, 1300 Elmwood Ave, Buffalo, New York, 14222
| | - Jamal B Williams
- Biology Department, SUNY Buffalo State, 1300 Elmwood Ave, Buffalo, New York, 14222
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136
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Srinivas M, Verselis VK, White TW. Human diseases associated with connexin mutations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:192-201. [PMID: 28457858 DOI: 10.1016/j.bbamem.2017.04.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 01/11/2023]
Abstract
Gap junctions and hemichannels comprised of connexins impact many cellular processes. Significant advances in our understanding of the functional role of these channels have been made by the identification of a host of genetic diseases caused by connexin mutations. Prominent features of connexin disorders are the inability of other connexins expressed in the same cell type to compensate for the mutated one, and the ability of connexin mutants to dominantly influence the activity of other wild-type connexins. Functional studies have begun to identify some of the underlying mechanisms whereby connexin channel mutation contributes to the disease state. Detailed mechanistic understanding of these functional differences will help to facilitate new pathophysiology driven therapies for the diverse array of connexin genetic disorders. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Miduturu Srinivas
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY 10036, USA
| | - Vytas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA.
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137
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Spatio-temporal regulation of connexin43 phosphorylation and gap junction dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:83-90. [PMID: 28414037 DOI: 10.1016/j.bbamem.2017.04.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/05/2017] [Accepted: 04/11/2017] [Indexed: 01/23/2023]
Abstract
Gap junctions are specialized membrane domains containing tens to thousands of intercellular channels. These channels permit exchange of small molecules (<1000Da) including ions, amino acids, nucleotides, metabolites and secondary messengers (e.g., calcium, glucose, cAMP, cGMP, IP3) between cells. The common reductionist view of these structures is that they are composed entirely of integral membrane proteins encoded by the 21 member connexin human gene family. However, it is clear that the normal physiological function of this structure requires interaction and regulation by a variety of proteins, especially kinases. Phosphorylation is capable of directly modulating connexin channel function but the most dramatic effects on gap junction activity occur via the organization of the gap junction structures themselves. This is a direct result of the short half-life of the primary gap junction protein, connexin, which requires them to be constantly assembled, remodeled and turned over. The biological consequences of this remodeling are well illustrated during cardiac ischemia, a process wherein gap junctions are disassembled and remodeled resulting in arrhythmia and ultimately heart failure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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138
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Friedl P, Mayor R. Tuning Collective Cell Migration by Cell-Cell Junction Regulation. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a029199. [PMID: 28096261 DOI: 10.1101/cshperspect.a029199] [Citation(s) in RCA: 221] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Collective cell migration critically depends on cell-cell interactions coupled to a dynamic actin cytoskeleton. Important cell-cell adhesion receptor systems implicated in controlling collective movements include cadherins, immunoglobulin superfamily members (L1CAM, NCAM, ALCAM), Ephrin/Eph receptors, Slit/Robo, connexins and integrins, and an adaptive array of intracellular adapter and signaling proteins. Depending on molecular composition and signaling context, cell-cell junctions adapt their shape and stability, and this gradual junction plasticity enables different types of collective cell movements such as epithelial sheet and cluster migration, branching morphogenesis and sprouting, collective network migration, as well as coordinated individual-cell migration and streaming. Thereby, plasticity of cell-cell junction composition and turnover defines the type of collective movements in epithelial, mesenchymal, neuronal, and immune cells, and defines migration coordination, anchorage, and cell dissociation. We here review cell-cell adhesion systems and their functions in different types of collective cell migration as key regulators of collective plasticity.
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Affiliation(s)
- Peter Friedl
- Department of Cell Biology, Radboud University Medical Centre, Nijmegen 6525GA, The Netherlands.,David H. Koch Center for Applied Research of Genitourinary Cancers, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030.,Cancer Genomics Center, 3584 CG Utrecht, The Netherlands
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom
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139
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Xu D, Liu T, Lin L, Li S, Hang X, Sun Y. Exposure to endosulfan increases endothelial permeability by transcellular and paracellular pathways in relation to cardiovascular diseases. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 223:111-119. [PMID: 28108160 DOI: 10.1016/j.envpol.2016.12.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/19/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
Exposure to environmental pollutants results in out-of-balance of vascular homeostasis. Endothelial dysfunction leads to a disruption of the endothelial permeability characteristics, associated with cardiovascular diseases. We previously reported that endosulfan could cause endothelial dysfunction, but the role of endosulfan in permeability of endothelial cells has been unexplored. To elucidate molecular mechanism of endosulfan-induced changes in endothelial permeability, human umbilical vein endothelial cells (HUVECs) were exposed to endosulfan, followed by endothelial permeability analysis. The results showed that permeability of HUVECs was enhanced at 48 h after exposure to endosulfan in a dose-dependent manner. Immunofluorescence analysis demonstrated the disruptions of actin cytoskeleton and focal adhesion in endosulfan-exposed cells. Endosulfan activated MMP3/LAMC1/FAK signaling pathway, and downregulated ROCK and PXN in transcellular pathway. Endosulfan affected adherens junctions via E-cadherin and β-catenin, and impaired gap junctions through downregulation of Cx43 in paracellular pathway. We predicted four closely related human cardiovascular diseases in Nextbio, including shock, coronary arteriosclerosis, disorder of cardiac function and hypertensive disorder in relation to endosulfan exposure. Some genes such as ROCK2 and PXN were predicted to be key genes in these diseases. These findings suggest that endosulfan increased endothelial permeability by paracellular and transcellular pathways, implicating the potential correlation between endosulfan and cardiovascular diseases.
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Affiliation(s)
- Dan Xu
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
| | - Tong Liu
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
| | - Limei Lin
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
| | - Shuai Li
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
| | - Xiaoming Hang
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
| | - Yeqing Sun
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1, Dalian, 116026, PR China.
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140
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Identifying connexin expression and determining gap junction intercellular communication in rainbow trout cells. In Vitro Cell Dev Biol Anim 2017; 53:406-416. [PMID: 28342022 DOI: 10.1007/s11626-017-0138-1] [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: 09/13/2016] [Accepted: 01/27/2017] [Indexed: 10/19/2022]
Abstract
Gap junctions are groups of membrane-bound channels that allow the passage of small molecules and ions between cells, permitting cell-cell communication. Because of their importance in cell homeostasis, gap junction presence and function were characterized in three commonly studied rainbow trout cell lines, namely RTgill-W1, RTgutGC, and RTG-2. Firstly, gap junction presence was determined by screening for gap junction protein alpha 7 and alpha 1 (GJA7 and GJA1) presence at the transcript level and GJA7 at the protein level. GJA7 was successfully identified at both the transcript and protein levels, and GJA1 was detected at the transcript level in all three cell lines. This is the first report of a GJA7 full-length transcript sequence in rainbow trout cells. Gap junction function, as determined by gap junction intercellular communication (GJIC), was examined using Lucifer yellow dye migration with the scrape and load technique; visualized by fluorescence microscopy. Phorbol 12-myristate 13-acetate (PMA), a gap junction inhibitor, was used to confirm the presence of functional gap junctions. Effects of serum deprivation on GJIC were also monitored; 24-h serum deprivation resulted in greater dye migration compared with 30-min serum deprivation. Both RTG-2 and RTgill-W1 showed significant dye migration that was inhibited by PMA while RTgutGC did not. Human foreskin fibroblast (HFF-1) cells were used as a positive control for gap junction presence and function. Taken together, our study shows that rainbow trout cells express connexin transcripts and proteins, and RTG-2 and, to a lesser extent, RTgill-W1 cells are able to perform GJIC.
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141
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Analysis of Epidermal Growth Factor Receptor Related Gene Expression Changes in a Cellular and Animal Model of Parkinson's Disease. Int J Mol Sci 2017; 18:ijms18020430. [PMID: 28212331 PMCID: PMC5343964 DOI: 10.3390/ijms18020430] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/27/2017] [Accepted: 02/08/2017] [Indexed: 02/01/2023] Open
Abstract
We employed transcriptome analysis of epidermal growth factor receptor related gene expression changes in cellular and animal models of Parkinson’s disease (PD). We used a well-known Parkinsonian toxin 1-methyl-4-phenylpyridine (MPP+) to induce neuronal apoptosis in the human neuroblastoma SH-SY5Y cell line. The MPP+-treatment of SH-SY5Y cells was capable of inducing neuro-apoptosis, but it remains unclear what kinds of transcriptional genes are affected by MPP+ toxicity. Therefore the pathways that were significantly perturbed in MPP+ treated human neuroblastoma SH-SY5Y cells were identified based on genome-wide gene expression data at two time points (24 and 48 h). We found that the Epidermal Growth Factor Receptor (EGFR) pathway-related genes showed significantly differential expression at all time points. The EGFR pathway has been linked to diverse cellular events such as proliferation, differentiation, and apoptosis. Further, to evaluate the functional significance of the altered EGFR related gene expression observed in MPP+-treated SH-SY5Y cells, the EGFR related GJB2 (Cx26) gene expression was analyzed in an MPP+-intoxicated animal PD model. Our findings identify that the EGFR signaling pathway and its related genes, such as Cx26, might play a significant role in dopaminergic (DAergic) neuronal cell death during the process of neuro-apoptosis and therefore can be focused on as potential targets for therapeutic intervention.
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142
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Liu Q, Ji X, Ge Z, Diao H, Chang X, Wang L, Wu Q. Role of connexin 43 in cadmium-induced proliferation of human prostate epithelial cells. J Appl Toxicol 2017; 37:933-942. [PMID: 28176351 DOI: 10.1002/jat.3441] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/21/2016] [Accepted: 12/23/2016] [Indexed: 12/21/2022]
Abstract
Connexins (Cxs), the subunits of gap junction channels, are involved in many physiological processes. Aberrant control of Cxs and gap junction intercellular communication may contribute to many diseases, including the promotion of cancer. Cd exposure is associated with increased risk of human prostate cancer and benign prostatic hyperplasia. The roles of Cxs in the effects of Cd on the prostate have, however, not been reported previously. In this study, the human prostate epithelial cell line RWPE-1 was exposed to Cd. A low dose of Cd stimulated cell proliferation along with a lower degree of gap junction intercellular communication and an elevated level of the protein Cx43. Cd exposure increased the levels of intracellular Ca2+ and phosphorylated Cx43 at the Ser368 site. Knockdown of Cx43 using siRNA blocked Cd-induced proliferation and interfered with the Cd-induced changes in the protein levels of cyclin D1, cyclin B1, p27Kip1 (p27) and p21Waf1/Cip1 (p21). The increase in Cx43 expression induced by Cd was presumably mediated by the androgen receptor, because it was abolished upon treatment with the androgen receptor antagonist, flutamide. Thus, a low dose of Cd promotes cell proliferation in RWPE-1, possibly mediated by Cx43 expression through an effect on cell cycle-associated proteins. Cx43 might be a target for prostatic diseases associated with Cd exposure. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Qingping Liu
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
| | - Xiaoli Ji
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
| | - Zehe Ge
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
| | - Haipeng Diao
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
| | - Xiuli Chang
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
| | - Lihua Wang
- Shanghai Jinshan District Center for Disease Control & Prevention, Weisheng Road, Jinshan District, Shanghai, 201599, China
| | - Qing Wu
- School of Public Health, Fudan University, DongAn Road, Shanghai, 200032, China.,Key Laboratory of Public Health Safety, Ministry of Education, DongAn Road, Shanghai, 200032, China
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143
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Manjarrez-Marmolejo J, Franco-Pérez J. Gap Junction Blockers: An Overview of their Effects on Induced Seizures in Animal Models. Curr Neuropharmacol 2017; 14:759-71. [PMID: 27262601 PMCID: PMC5050393 DOI: 10.2174/1570159x14666160603115942] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 02/26/2016] [Accepted: 04/21/2016] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Gap junctions are clusters of intercellular channels allowing the bidirectional pass of ions directly into the cytoplasm of adjacent cells. Electrical coupling mediated by gap junctions plays a role in the generation of highly synchronized electrical activity. The hypersynchronous neuronal activity is a distinctive characteristic of convulsive events. Therefore, it has been postulated that enhanced gap junctional communication is an underlying mechanism involved in the generation and maintenance of seizures. There are some chemical compounds characterized as gap junction blockers because of their ability to disrupt the gap junctional intercellular communication. OBJECTIVE Hence, the aim of this review is to analyze the available data concerning the effects of gap junction blockers specifically in seizure models. RESULTS Carbenoxolone, quinine, mefloquine, quinidine, anandamide, oleamide, heptanol, octanol, meclofenamic acid, niflumic acid, flufenamic acid, glycyrrhetinic acid and retinoic acid have all been evaluated on animal seizure models. In vitro, these compounds share anticonvulsant effects typically characterized by the reduction of both amplitude and frequency of the epileptiform activity induced in brain slices. In vivo, gap junction blockers modify the behavioral parameters related to seizures induced by 4-aminopyridine, pentylenetetrazole, pilocarpine, penicillin and maximal electroshock. CONCLUSION Although more studies are still required, these molecules could be a promising avenue in the search for new pharmaceutical alternatives for the treatment of epilepsy.
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Affiliation(s)
| | - Javier Franco-Pérez
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, M.V.S. Insurgentes Sur 3877, Col. La Fama, C.P. 14269, Mexico D.F., Mexico
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144
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Belousov AB, Fontes JD, Freitas-Andrade M, Naus CC. Gap junctions and hemichannels: communicating cell death in neurodevelopment and disease. BMC Cell Biol 2017; 18:4. [PMID: 28124625 PMCID: PMC5267333 DOI: 10.1186/s12860-016-0120-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gap junctions are unique membrane channels that play a significant role in intercellular communication in the developing and mature central nervous system (CNS). These channels are composed of connexin proteins that oligomerize into hexamers to form connexons or hemichannels. Many different connexins are expressed in the CNS, with some specificity with regard to the cell types in which distinct connexins are found, as well as the timepoints when they are expressed in the developing and mature CNS. Both the main neuronal Cx36 and glial Cx43 play critical roles in neurodevelopment. These connexins also mediate distinct aspects of the CNS response to pathological conditions. An imbalance in the expression, translation, trafficking and turnover of connexins, as well as mutations of connexins, can impact their function in the context of cell death in neurodevelopment and disease. With the ever-increasing understanding of connexins in the brain, therapeutic strategies could be developed to target these membrane channels in various neurological disorders.
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Affiliation(s)
- Andrei B Belousov
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Joseph D Fontes
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Moises Freitas-Andrade
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Christian C Naus
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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145
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Dukic AR, Haugen LH, Pidoux G, Leithe E, Bakke O, Taskén K. A protein kinase A-ezrin complex regulates connexin 43 gap junction communication in liver epithelial cells. Cell Signal 2017; 32:1-11. [PMID: 28077322 DOI: 10.1016/j.cellsig.2017.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/04/2016] [Accepted: 01/04/2017] [Indexed: 12/15/2022]
Abstract
Communication between adjacent cells can occur via gap junctions (GJ) composed of connexin (Cx) hexamers that allow passage of small molecules. One of the most widely and highly expressed Cxs in human tissues is Cx43, shown to be regulated through phosphorylation by several kinases including PKA. Ezrin is a membrane associated protein that can serve as an A-kinase anchoring protein (AKAP) and hold an anchored pool of PKA. Here, we used the liver epithelial cell line IAR20, which expresses Cx43 as the predominant GJ protein, to test the hypothesis that Ezrin may associate with Cx43 in cell types that form stable GJs and serve as an AKAP. Our biochemical and proteomics data indicate that Ezrin associates with Cx43 in epithelial cells. Analyses by confocal immunofluorescence microscopy and proximity ligation assays demonstrate that Ezrin and Cx43 co-localize, together with zonula occludens-1 (ZO-1) and PKA RIα and RIIα, at the cell membrane. Quantitative gap-FRAP experiments show increased GJ intercellular communication after cAMP stimulation. Moreover, loading of cells with the Ht31 peptide that displaces both PKA RIα and RIIα from the AKAP or a peptide that disrupts the Cx43-Ezrin interaction reverts the effect and reduces the level of communication, supporting the hypothesis that in IAR20 cells Ezrin associates with Cx43 (in complex with ZO-1) which places PKA in proximity to Cx43, enabling its phosphorylation and GJ opening.
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Affiliation(s)
- Aleksandra R Dukic
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Linda Hofstad Haugen
- Department of Biosciences, Centre for Immune Regulation, University of Oslo, Oslo, Norway
| | - Guillaume Pidoux
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Edward Leithe
- Department of Molecular Oncology, Institute for Cancer Research, Oslo University Hospital HE - Norwegian Radium Hospital, Oslo, Norway
| | - Oddmund Bakke
- Department of Biosciences, Centre for Immune Regulation, University of Oslo, Oslo, Norway
| | - Kjetil Taskén
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo and Oslo University Hospital, Oslo, Norway; K.G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway; Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway.
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146
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Wong SH, Wang WH, Chen PH, Li SY, Yang JJ. Functional analysis of a nonsyndromic hearing loss-associated mutation in the transmembrane II domain of the GJC3 gene. Int J Med Sci 2017; 14:246-256. [PMID: 28367085 PMCID: PMC5370287 DOI: 10.7150/ijms.17785] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/12/2016] [Indexed: 11/05/2022] Open
Abstract
In a previous study, we identified a novel missense mutation, p.W77S, in the GJC3 gene encoding connexin30.2/connexin31.3 (CX30.2/CX31.3) from patients with hearing loss. The functional alteration of CX30.2/CX31.3 caused by the p.W77S mutant of GJC3 gene, however, remains unclear. In the current study, our result indicated that the p.W77 is localized at the second membrane-spanning segments (TM2) and near border of the E1 domain of the CX30.2/CX31.3 protein and highly conserved (Conseq score = 8~9) in all species. The p.W77S missense mutation proteins in the intracellular distribution are different CX30.2/CX31.3WT and an accumulation of the mutant protein in the endoplasmic reticulum (ER) of the HeLa cell. Furthermore, co-expression of WT and p.W77S mutant chimerae proteins showed that the heteromeric connexon accumulated in the cytoplasm, thereby impairing the WT proteins' expression in the cell membranes. In addition, we found that CX30.2/CX31.3W77S missense mutant proteins were degraded by lysosomes and proteosomes in the transfected HeLa cell. Based on these findings, we suggest that p.W77S mutant has a dominant negative effect on the formation and function of the gap junction. These results give a novel molecular elucidation for the mutation of GJC3 in the development of hearing loss.
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Affiliation(s)
- Swee-Hee Wong
- Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Wen-Hung Wang
- Department of Otolaryngology, Cathay General Hospital, Taipei, Taiwan
| | - Pin-Hua Chen
- Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Shuan-Yow Li
- Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Jiann-Jou Yang
- Department of BioMedical Sciences, Chung Shan Medical University, Taichung, Taiwan;; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan
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147
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Chen Z, Xie X, Huang J, Gong W, Zhu X, Chen Q, Huang J, Huang H. Connexin43 regulates high glucose-induced expression of fibronectin, ICAM-1 and TGF-β1 via Nrf2/ARE pathway in glomerular mesangial cells. Free Radic Biol Med 2017; 102:77-86. [PMID: 27840317 DOI: 10.1016/j.freeradbiomed.2016.11.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/24/2016] [Accepted: 11/08/2016] [Indexed: 12/23/2022]
Abstract
Nrf2/ARE signaling pathway is a crucial cellular defense system to cope with oxidative stress, which is adaptively activated, in diabetic condition that is not efficient enough to resist the oxidative stress provoked by hyperglycemia. We have previously demonstrated that Connexin43 (Cx43) attenuates renal fibrosis through c-Src. However, the underlying mechanisms need to be further clarified. It has been reported that Cx43 possesses the ability of anti-oxidative. The current study aimed to determine if Cx43 exerts protective effects on renal fibrosis in diabetes via activation of Nrf2/ARE pathway and explore the underlying molecular mechanisms. The following findings were observed: (1) Cx43 expression decreased and c-Src activity increased in kidneys of diabetic animals; (2) Over-expressed Cx43 in high glucose treated GMCs inhibited protein levels of FN, ICAM-1 and TGF-β1; (3) Nrf2/ARE signaling adaptively responded to high glucose treatment in GMCs; (4) Cx43 reduced ROS generation by boost Nrf2/ARE signaling under high glucose condition; (5) Inhibition of c-Src activity promoted nucleus accumulation of Nrf2; (6) Over-expressed Cx43 inhibited c-Src activity and the interaction between c-Src and Nrf2 in GMCs cultured in high glucose. Thus we propose that Cx43 might enhance the activation of Nrf2/ARE pathway by means of inhibiting c-Src activity to hinder the nuclear export of Nrf2, and then reduce expression of FN, ICAM-1 and TGF-β1, ultimately attenuating renal fibrosis in diabetes.
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Affiliation(s)
- Zhiquan Chen
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xi Xie
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China; Department of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, China.
| | - Junying Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenyan Gong
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xiaoyu Zhu
- Department of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, China
| | - Qiuhong Chen
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jiani Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Heqing Huang
- Laboratory of Pharmacology & Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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148
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Polusani SR, Kalmykov EA, Chandrasekhar A, Zucker SN, Nicholson BJ. Cell coupling mediated by connexin 26 selectively contributes to reduced adhesivity and increased migration. J Cell Sci 2016; 129:4399-4410. [PMID: 27777264 DOI: 10.1242/jcs.185017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 10/20/2016] [Indexed: 11/20/2022] Open
Abstract
Gap junction proteins (connexins) have crucial effects on cell motility in many systems, from migration of neural crest cells to promotion of metastatic invasiveness. Here, we show that expression of Cx26 (also known as GJB2) in HeLa cells specifically enhances cell motility in scrape wounding and sparse culture models. This effect is dependent on gap junction channels and is isotype specific [Cx26 enhances motility, whereas Cx43 (also known as GJA1) does not and Cx32 (also known as GJB1) has an intermediate effect]. The increased motility is associated with reduced cell adhesiveness, caused by loss of N-cadherin protein and RNA at the wound edge. This in turn causes a redistribution of N-cadherin-binding proteins (p120 catenin and β-catenin) to the cytosol and nucleus, respectively. The former activates Rac-1, which mediates cytoskeletal rearrangements needed for filopod extension. The latter is associated with increased expression of urokinase plasminogen activating receptor (an activator of extracellular proteases) and secretion of extracellular matrix components like collagen. Although these effects were dependent on Cx26-mediated coupling of the cells, they are not mediated by the same signal (i.e. cAMP) through which Cx26 has been shown to suppress proliferation in the same system.
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Affiliation(s)
- Srikanth R Polusani
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Edward A Kalmykov
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Anjana Chandrasekhar
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Shoshanna N Zucker
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Bruce J Nicholson
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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149
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Ek Vitorín JF, Pontifex TK, Burt JM. Determinants of Cx43 Channel Gating and Permeation: The Amino Terminus. Biophys J 2016; 110:127-40. [PMID: 26745416 DOI: 10.1016/j.bpj.2015.10.054] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/11/2015] [Accepted: 10/30/2015] [Indexed: 11/30/2022] Open
Abstract
Separate connexin domains partake in proposed gating mechanisms of gap junction channels. The amino-terminus (NT) domains, which contribute to voltage sensing, may line the channel's cytoplasmic-facing funnel surface, stabilize the channel's overall structure through interactions with the transmembrane domains and each other, and integrate to form a compound particle to gate the channel closed. Interactions of the carboxyl-terminus (CT) and cytoplasmic loop (CL) domains underlie voltage- and low pH-triggered channel closure. To elucidate potential cooperation of these gating mechanisms, we replaced the Cx43NT with the Cx37NT (chimera Cx43(∗)NT37), leaving the remainder of the Cx43 sequence, including the CT and CL, unchanged. Compared to wild-type Cx43 (Cx43WT), Cx43(∗)NT37 junctions exhibited several functional alterations: extreme resistance to halothane- and acidification-induced uncoupling, absence of voltage-dependent fast inactivation, longer channel open times, larger unitary channel conductances, low junctional dye permeability/permselectivity, and an overall cation selectivity more typical of Cx37WT than Cx43WT junctions. Together, these results suggest a cohesive model of channel function wherein: 1) channel conductance and size selectivity are largely determined by pore diameter, whereas charge selectivity results from the NT domains, and 2) transition between fully open and (multiple) closed states involves global changes in structure of the pore-forming domains transduced by interactions of the pore-forming domains with either the NT, CT, or both, with the NT domains forming the gate of the completely closed channel.
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Affiliation(s)
| | - Tasha K Pontifex
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Janis M Burt
- Department of Physiology, University of Arizona, Tucson, Arizona
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150
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Slavi N, Wang Z, Harvey L, Schey KL, Srinivas M. Identification and Functional Assessment of Age-Dependent Truncations to Cx46 and Cx50 in the Human Lens. Invest Ophthalmol Vis Sci 2016; 57:5714-5722. [PMID: 27787559 PMCID: PMC5089213 DOI: 10.1167/iovs.16-19698] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 08/21/2016] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Many proteins in the lens undergo extensive posttranslational modifications (PTMs) with age, leading to alterations in their function. The extent to which lens gap junction proteins, Cx46 and Cx50, accumulate PTMs with aging is not known. In this study, we identified truncations in Cx46 and Cx50 in the human lens using mass spectrometry. We also examined the effect of truncations on channel function using electrophysiological measurements. METHODS Human lenses were dissected into cortex, outer nucleus, and nucleus regions, and fiber cell membranes were subjected to trypsin digestion. Tryptic peptides were analyzed by liquid chromatography (LC)-electrospray tandem mass spectrometry (ESI/MS/MS). Effects of truncations on channel conductance, permeability, and gating were assessed in transfected cells. RESULTS Cleavage sites were identified in the C-terminus, the cytoplasmic loop, and the N-terminus of Cx46 and Cx50. Levels of C-terminal truncations, which were found at residues 238 to 251 in Cx46 and at residues 238 to 253 and 274 to 284 in Cx50, were similar in different lens regions. In contrast, levels of truncations in cytoplasmic loop and N-terminal domains of Cx46 and Cx50 increased dramatically from outer cortex to nucleus. Most of the C-terminally truncated proteins were functional, whereas truncations in the cytoplasmic loop did not result in the formation of functional channels. CONCLUSIONS Accumulation of cytoplasmic loop and N-terminal truncations in the core might lead to decreases in coupling with age. This reduction is expected to lead to an increase in intracellular calcium and a decrease in levels of glutathione in the nucleus. These changes may ultimately lead to age-related nuclear cataracts.
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Affiliation(s)
- Nefeli Slavi
- Department of Biological and Vision Sciences and the Graduate Center for Vision Research, SUNY College of Optometry, New York, New York, United States
| | - Zhen Wang
- Department of Biochemistry and Mass Spectrometry Research Center Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Lucas Harvey
- Department of Biological and Vision Sciences and the Graduate Center for Vision Research, SUNY College of Optometry, New York, New York, United States
| | - Kevin L. Schey
- Department of Biochemistry and Mass Spectrometry Research Center Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Miduturu Srinivas
- Department of Biological and Vision Sciences and the Graduate Center for Vision Research, SUNY College of Optometry, New York, New York, United States
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