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Abstract
PURPOSE OF REVIEW To describe the current knowledge on the cross-talk between connexins and microRNAs (miRs) in bone cells. RECENT FINDINGS Connexins play a crucial role on bone development and maintenance, and disruptions in their abundance or localization can affect how bone perceives and responds to mechanical, hormonal, and pharmacological stimuli. Connexin expression can be modified by miRs, which modulate connexin mRNA and protein levels. Recently, different manners by which miRs and connexins can interact in bone have been identified, including mechanisms that mediate miR exchange between cells in direct contact through gap junctions, or between distant cells via extracellular vesicles (EVs). SUMMARY We bring to light the relationship between miRs and connexins in bone tissue, with special focus on regulatory effects of miRs and connexins on gene expression, as well as the mechanisms that mediate miR exchange between cells in direct contact through gap junctions, or between distant cells via EVs.
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Mittal R, Debs LH, Nguyen D, Patel AP, Grati M, Mittal J, Yan D, Eshraghi AA, Liu XZ. Signaling in the Auditory System: Implications in Hair Cell Regeneration and Hearing Function. J Cell Physiol 2017; 232:2710-2721. [DOI: 10.1002/jcp.25695] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 11/18/2016] [Indexed: 02/06/2023]
Affiliation(s)
- Rahul Mittal
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Luca H. Debs
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Desiree Nguyen
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Amit P. Patel
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - M'hamed Grati
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Jeenu Mittal
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Denise Yan
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Adrien A. Eshraghi
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Xue Zhong Liu
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
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Varela-Eirin M, Varela-Vazquez A, Rodríguez-Candela Mateos M, Vila-Sanjurjo A, Fonseca E, Mascareñas JL, Eugenio Vázquez M, Mayan MD. Recruitment of RNA molecules by connexin RNA-binding motifs: Implication in RNA and DNA transport through microvesicles and exosomes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:728-736. [PMID: 28167212 DOI: 10.1016/j.bbamcr.2017.02.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/26/2017] [Accepted: 02/02/2017] [Indexed: 12/16/2022]
Abstract
Connexins (Cxs) are integral membrane proteins that form high-conductance plasma membrane channels, allowing communication from cell to cell (via gap junctions) and from cells to the extracellular environment (via hemichannels). Initially described for their role in joining excitable cells (nerve and muscle), gap junctions (GJs) are found between virtually all cells in solid tissues and are essential for functional coordination by enabling the direct transfer of small signalling molecules, metabolites, ions, and electrical signals from cell to cell. Several studies have revealed diverse channel-independent functions of Cxs, which include the control of cell growth and tumourigenicity. Connexin43 (Cx43) is the most widespread Cx in the human body. The myriad roles of Cx43 and its implication in the development of disorders such as cancer, inflammation, osteoarthritis and Alzheimer's disease have given rise to many novel questions. Several RNA- and DNA-binding motifs were predicted in the Cx43 and Cx26 sequences using different computational methods. This review provides insights into new, ground-breaking functions of Cxs, highlighting important areas for future work such as transfer of genetic information through extracellular vesicles. We discuss the implication of potential RNA- and DNA-binding domains in the Cx43 and Cx26 sequences in the cellular communication and control of signalling pathways.
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Affiliation(s)
- Marta Varela-Eirin
- CellCOM research group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), Servizo Galego de Saúde (SERGAS), University of A Coruña, Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Adrian Varela-Vazquez
- CellCOM research group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), Servizo Galego de Saúde (SERGAS), University of A Coruña, Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Marina Rodríguez-Candela Mateos
- CellCOM research group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), Servizo Galego de Saúde (SERGAS), University of A Coruña, Xubias de Arriba, 84 15006 A Coruña, Spain
| | - Anton Vila-Sanjurjo
- Grupo GIBE, Departamento de Bioloxía Celular e Molecular, Facultade de Ciencias, Universidade de A Coruña (UDC), Campus Zapateira, s/n 15.071, A Coruña, Spain
| | - Eduardo Fonseca
- CellCOM research group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), Servizo Galego de Saúde (SERGAS), University of A Coruña, Xubias de Arriba, 84 15006 A Coruña, Spain
| | - José L Mascareñas
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain; Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain; Departamento de Química Inorgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - M Eugenio Vázquez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain; Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain; Departamento de Química Inorgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
| | - Maria D Mayan
- CellCOM research group, Instituto de Investigación Biomédica de A Coruña (INIBIC), CH-Universitario A Coruña (XXIAC), Servizo Galego de Saúde (SERGAS), University of A Coruña, Xubias de Arriba, 84 15006 A Coruña, Spain.
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Inhibition of fat cell differentiation in 3T3-L1 pre-adipocytes by all-trans retinoic acid: Integrative analysis of transcriptomic and phenotypic data. BIOMOLECULAR DETECTION AND QUANTIFICATION 2016; 11:31-44. [PMID: 28331816 PMCID: PMC5348118 DOI: 10.1016/j.bdq.2016.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/08/2016] [Accepted: 11/15/2016] [Indexed: 01/10/2023]
Abstract
The process of adipogenesis is controlled in a highly orchestrated manner, including transcriptional and post-transcriptional events. In developing 3T3-L1 pre-adipocytes, this program can be interrupted by all-trans retinoic acid (ATRA). To examine this inhibiting impact by ATRA, we generated large-scale transcriptomic data on the microRNA and mRNA level. Non-coding RNAs such as microRNAs represent a field in RNA turnover, which is very important for understanding the regulation of mRNA gene expression. High throughput mRNA and microRNA expression profiling was performed using mRNA hybridisation microarray technology and multiplexed expression assay for microRNA quantification. After quantitative measurements we merged expression data sets, integrated the results and analysed the molecular regulation of in vitro adipogenesis. For this purpose, we applied local enrichment analysis on the integrative microRNA-mRNA network determined by a linear regression approach. This approach includes the target predictions of TargetScan Mouse 5.2 and 23 pre-selected, significantly regulated microRNAs as well as Affymetrix microarray mRNA data. We found that the cellular lipid metabolism is negatively affected by ATRA. Furthermore, we were able to show that microRNA 27a and/or microRNA 96 are important regulators of gap junction signalling, the rearrangement of the actin cytoskeleton as well as the citric acid cycle, which represent the most affected pathways with regard to inhibitory effects of ATRA in 3T3-L1 preadipocytes. In conclusion, the experimental workflow and the integrative microRNA–mRNA data analysis shown in this study represent a possibility for illustrating interactions in highly orchestrated biological processes. Further the applied global microRNA–mRNA interaction network may also be used for the pre-selection of potential new biomarkers with regard to obesity or for the identification of new pharmaceutical targets.
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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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Carcinoma-astrocyte gap junctions promote brain metastasis by cGAMP transfer. Nature 2016; 533:493-498. [PMID: 27225120 PMCID: PMC5021195 DOI: 10.1038/nature18268] [Citation(s) in RCA: 640] [Impact Index Per Article: 80.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 04/12/2016] [Indexed: 01/21/2023]
Abstract
Brain metastasis represents a substantial source of morbidity and mortality in various cancers, and is characterized by high resistance to chemotherapy. Here we define the role of the most abundant cell type in the brain, the astrocyte, in promoting brain metastasis. Breast and lung cancer cells express protocadherin 7 (PCDH7) to favor the assembly of carcinoma-astrocyte gap junctions composed of connexin 43 (Cx43). Once engaged with the astrocyte gap-junctional network, brain metastatic cancer cells employ these channels to transfer the second messenger cGAMP to astrocytes, activating the STING pathway and production of inflammatory cytokines IFNα and TNFα. As paracrine signals, these factors activate the STAT1 and NF-κB pathways in brain metastatic cells, which support tumour growth and chemoresistance. The orally bioavailable modulators of gap junctions meclofenamate and tonabersat break this paracrine loop, and we provide proof-of-principle for the applicability of this therapeutic strategy to treat established brain metastasis.
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Schmidt K, Windler R, de Wit C. Communication Through Gap Junctions in the Endothelium. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 77:209-40. [PMID: 27451099 DOI: 10.1016/bs.apha.2016.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A swarm of fish displays a collective behavior (swarm behavior) and moves "en masse" despite the huge number of individual animals. In analogy, organ function is supported by a huge number of cells that act in an orchestrated fashion and this applies also to vascular cells along the vessel length. It is obvious that communication is required to achieve this vital goal. Gap junctions with their modular bricks, connexins (Cxs), provide channels that interlink the cytosol of adjacent cells by a pore sealed against the extracellular space. This allows the transfer of ions and charge and thereby the travel of membrane potential changes along the vascular wall. The endothelium provides a low-resistance pathway that depends crucially on connexin40 which is required for long-distance conduction of dilator signals in the microcirculation. The experimental evidence for membrane potential changes synchronizing vascular behavior is manifold but the functional verification of a physiologic role is still open. Other molecules may also be exchanged that possibly contribute to the synchronization (eg, Ca(2+)). Recent data suggest that vascular Cxs have more functions than just facilitating communication. As pharmacological tools to modulate gap junctions are lacking, Cx-deficient mice provide currently the standard to unravel their vascular functions. These include arteriolar dilation during functional hyperemia, hypoxic pulmonary vasoconstriction, vascular collateralization after ischemia, and feedback inhibition on renin secretion in the kidney.
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Affiliation(s)
- K Schmidt
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - R Windler
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - C de Wit
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany.
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58
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Oshima A, Matsuzawa T, Murata K, Tani K, Fujiyoshi Y. Hexadecameric structure of an invertebrate gap junction channel. J Mol Biol 2016; 428:1227-1236. [DOI: 10.1016/j.jmb.2016.02.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 12/12/2022]
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Spagnol G, Kieken F, Kopanic JL, Li H, Zach S, Stauch KL, Grosely R, Sorgen PL. Structural Studies of the Nedd4 WW Domains and Their Selectivity for the Connexin43 (Cx43) Carboxyl Terminus. J Biol Chem 2016; 291:7637-50. [PMID: 26841867 DOI: 10.1074/jbc.m115.701417] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 12/13/2022] Open
Abstract
Neuronal precursor cell-expressed developmentally down-regulated 4 (Nedd4) was the first ubiquitin protein ligase identified to interact with connexin43 (Cx43), and its suppressed expression results in accumulation of gap junction plaques at the plasma membrane. Nedd4-mediated ubiquitination of Cx43 is required to recruit Eps15 and target Cx43 to the endocytic pathway. Although the Cx43 residues that undergo ubiquitination are still unknown, in this study we address other unresolved questions pertaining to the molecular mechanisms mediating the direct interaction between Nedd4 (WW1-3 domains) and Cx43 (carboxyl terminus (CT)). All three WW domains display a similar three antiparallel β-strand structure and interact with the same Cx43CT(283)PPXY(286)sequence. Although Tyr(286)is essential for the interaction, MAPK phosphorylation of the preceding serine residues (Ser(P)(279)and Ser(P)(282)) increases the binding affinity by 2-fold for the WW domains (WW2 > WW3 ≫ WW1). The structure of the WW2·Cx43CT(276-289)(Ser(P)(279), Ser(P)(282)) complex reveals that coordination of Ser(P)(282)with the end of β-strand 3 enables Ser(P)(279)to interact with the back face of β-strand 3 (Tyr(286)is on the front face) and loop 2, forming a horseshoe-shaped arrangement. The close sequence identity of WW2 with WW1 and WW3 residues that interact with the Cx43CT PPXY motif and Ser(P)(279)/Ser(P)(282)strongly suggests that the significantly lower binding affinity of WW1 is the result of a more rigid structure. This study presents the first structure illustrating how phosphorylation of the Cx43CT domain helps mediate the interaction with a molecular partner involved in gap junction regulation.
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Affiliation(s)
- Gaelle Spagnol
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Fabien Kieken
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | | | - Hanjun Li
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Sydney Zach
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Kelly L Stauch
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Rosslyn Grosely
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
| | - Paul L Sorgen
- From the University of Nebraska Medical Center, Omaha, Nebraska 68105
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60
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Watanabe M, Sawada R, Aramaki T, Skerrett IM, Kondo S. The Physiological Characterization of Connexin41.8 and Connexin39.4, Which Are Involved in the Striped Pattern Formation of Zebrafish. J Biol Chem 2016; 291:1053-63. [PMID: 26598520 PMCID: PMC4714190 DOI: 10.1074/jbc.m115.673129] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 11/02/2015] [Indexed: 11/06/2022] Open
Abstract
The zebrafish has a striped skin pattern on its body, and Connexin41.8 (Cx41.8) and Cx39.4 are involved in striped pattern formation. Mutations in these connexins change the striped pattern to a spot or labyrinth pattern. In this study, we characterized Cx41.8 and Cx39.4 after expression in Xenopus oocytes. In addition, we analyzed Cx41.8 mutants Cx41.8I203F and Cx41.8M7, which caused spot or labyrinth skin patterns, respectively, in transgenic zebrafish. In the electrophysiological analysis, the gap junctions formed by Cx41.8 and Cx39.4 showed distinct sensitivity to transjunctional voltage. Analysis of non-junctional (hemichannel) currents revealed a large voltage-dependent current in Cx39.4-expressing oocytes that was absent in cells expressing Cx41.8. Junctional currents induced by both Cx41.8 and Cx39.4 were reduced by co-expression of Cx41.8I203F and abolished by co-expression of Cx41.8M7. In the transgenic experiment, Cx41.8I203F partially rescued the Cx41.8 null mutant phenotype, whereas Cx41.8M7 failed to rescue the null mutant, and it elicited a more severe phenotype than the Cx41.8 null mutant, as evidenced by a smaller spot pattern. Our results provide evidence that gap junctions formed by Cx41.8 play an important role in stripe/spot patterning and suggest that mutations in Cx41.8 can effect patterning by way of reduced function (I203F) and dominant negative effects (M7). Our results suggest that functional differences in Cx41.8 and Cx39.4 relate to spot or labyrinth mutant phenotypes and also provide evidence that these two connexins interact in vivo and in vitro.
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Affiliation(s)
- Masakatsu Watanabe
- From the Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan,
| | - Risa Sawada
- From the Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihiro Aramaki
- From the Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - I Martha Skerrett
- the Biology Department, Buffalo State College, Buffalo, New York, 14222, and
| | - Shigeru Kondo
- From the Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan, CREST, Japan Science and Technology Agency, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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Cellular mechanisms of human atherosclerosis: Role of cell-to-cell communications in subendothelial cell functions. Tissue Cell 2015; 48:25-34. [PMID: 26747411 DOI: 10.1016/j.tice.2015.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 12/16/2022]
Abstract
The present study was undertaken in order to extend of our earlier work, focusing on the analysis of roles of cell-to-cell communications in the regulation of the subendothelial cell function. In present study, we have found that the expression of connexin43 (Cx43) is dramatically reduced in human atherosclerotic lesions, compared with undiseased intima. In atherosclerotic lesions, the number of so-called 'connexin plaques' was found to be lower in lipid-laden cells than in cells which were free from lipid inclusions. In primary cell culture, subendothelial intimal cells tended to create multicellular structures in the form of clusters. Cluster creation was accompanied by the formation of gap junctions between cells; the degree of gap junctional communication correlated with the density of cells in culture. We found that atherosclerosis-related processes such as DNA synthesis, protein synthesis and accumulation of intracellular cholesterol correlated with the degree of cell-to-cell communication. The relation of DNA and protein synthesis with cell-to-cell communication could be described as "bell-shaped". We further incubated cells, cultured from undiseased subendothelial intima, with various forms of modified LDL causing intracellular cholesterol accumulation. After the incubation of intimal cells with modified LDL, intercellular communication has "dropped" considerably. The findings indicate that intracellular lipid accumulation might be a reason for a decrease of the number of gap junctions. The findings also suggest that the disintegration of cellular network is associated with foam cell formation, the process known as a key event of atherogenesis.
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Bai D. Structural analysis of key gap junction domains--Lessons from genome data and disease-linked mutants. Semin Cell Dev Biol 2015; 50:74-82. [PMID: 26658099 DOI: 10.1016/j.semcdb.2015.11.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 11/26/2015] [Indexed: 12/27/2022]
Abstract
A gap junction (GJ) channel is formed by docking of two GJ hemichannels and each of these hemichannels is a hexamer of connexins. All connexin genes have been identified in human, mouse, and rat genomes and their homologous genes in many other vertebrates are available in public databases. The protein sequences of these connexins align well with high sequence identity in the same connexin across different species. Domains in closely related connexins and several residues in all known connexins are also well-conserved. These conserved residues form signatures (also known as sequence logos) in these domains and are likely to play important biological functions. In this review, the sequence logos of individual connexins, groups of connexins with common ancestors, and all connexins are analyzed to visualize natural evolutionary variations and the hot spots for human disease-linked mutations. Several gap junction domains are homologous, likely forming similar structures essential for their function. The availability of a high resolution Cx26 GJ structure and the subsequently-derived homology structure models for other connexin GJ channels elevated our understanding of sequence logos at the three-dimensional GJ structure level, thus facilitating the understanding of how disease-linked connexin mutants might impair GJ structure and function. This knowledge will enable the design of complementary variants to rescue disease-linked mutants.
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Affiliation(s)
- Donglin Bai
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada N6A 5C1.
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63
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Christodoulou N, Skourides P. Cell-Autonomous Ca 2+ Flashes Elicit Pulsed Contractions of an Apical Actin Network to Drive Apical Constriction during Neural Tube Closure. Cell Rep 2015; 13:2189-202. [DOI: 10.1016/j.celrep.2015.11.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 09/13/2015] [Accepted: 11/03/2015] [Indexed: 01/08/2023] Open
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Sala G, Badalamenti S, Ponticelli C. The Renal Connexome and Possible Roles of Connexins in Kidney Diseases. Am J Kidney Dis 2015; 67:677-87. [PMID: 26613807 DOI: 10.1053/j.ajkd.2015.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022]
Abstract
Connexins are membrane-spanning proteins that allow for the formation of cell-to-cell channels and cell-to-extracellular space hemichannels. Many connexin subtypes are expressed in kidney cells. Some mutations in connexin genes have been linked to various human pathologies, including cardiovascular, neurodegenerative, lung, and skin diseases, but the exact role of connexins in kidney disease remains unclear. Some hypotheses about a connection between genetic mutations, endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) in kidney pathology have been explored. The potential relationship of kidney disease to abnormal production of connexin proteins, mutations in their genes together with ER stress, or the UPR is still a matter of debate. In this scenario, it is tantalizing to speculate about a possible role of connexins in the setting of kidney pathologies that are thought to be caused by a deregulated podocyte protein expression, the so-called podocytopathies. In this article, we give examples of the roles of connexins in kidney (patho)physiology and propose avenues for further research concerning connexins, ER stress, and UPR in podocytopathies that may ultimately help refine drug treatment.
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Affiliation(s)
- Gabriele Sala
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy.
| | - Salvatore Badalamenti
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
| | - Claudio Ponticelli
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
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65
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Liu Y, Wen Q, Chen XL, Yang SJ, Gao L, Gao L, Zhang C, Li JL, Xiang XX, Wan K, Chen XH, Zhang X, Zhong JF. All-trans retinoic acid arrests cell cycle in leukemic bone marrow stromal cells by increasing intercellular communication through connexin 43-mediated gap junction. J Hematol Oncol 2015; 8:110. [PMID: 26446715 PMCID: PMC4597383 DOI: 10.1186/s13045-015-0212-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/28/2015] [Indexed: 01/28/2023] Open
Abstract
Background Gap junctional intercellular communication (GJIC) is typically decreased in malignant tumors. Gap junction is not presented between hematopoietic cells but occurred in bone marrow stromal cells (BMSCs). Connexin 43 (Cx43) is the major gap junction (GJ) protein; our previous study revealed that Cx43 expression and GJIC were decreased in acute leukemic BMSCs. All-trans retinoic acid (ATRA) increases GJIC in a variety of cancer cells and has been used to treat acute promyelocytic leukemia, but the effects of ATRA on leukemic BMSCs is unknown. In this study, we evaluated the potential effects of ATRA on cell cycle, proliferation, and apoptosis of leukemic BMSCs. Effects of ATRA on Cx43 expression and GJIC were also examined. Methods Human BMSCs obtained from 25 patients with primary acute leukemia, and 10 normal healthy donors were cultured. Effects of ATRA on cell cycle, cell proliferation, and apoptosis were examined with or without co-treatment with amphotericin-B. Cx43 expression was examined at both the mRNA and protein expression levels. GJIC was examined by using a dye transfer assay and measuring the rate of fluorescence recovery after photobleaching (FRAP). Results ATRA arrested the cell cycle progression, inhibited cell growth, and increased apoptosis in leukemic BMSCs. Both Cx43 expression and GJIC function were increased by ATRA treatment. Most of the observed effects mediated by ATRA were abolished by amphotericin-B pretreatment. Conclusions ATRA arrests cell cycle progression in leukemic BMSCs, likely due to upregulating Cx43 expression and enhancing GJIC function. Electronic supplementary material The online version of this article (doi:10.1186/s13045-015-0212-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yao Liu
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China. .,Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Qin Wen
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xue-Lian Chen
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Shi-Jie Yang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Lei Gao
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Li Gao
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Cheng Zhang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Jia-Li Li
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xi-Xi Xiang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Kai Wan
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xing-Hua Chen
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Xi Zhang
- Department of Hematology, Xinqiao Hospital, the Third Military Medical University, Xinqiao Street, Chongqing, 400037, China.
| | - Jiang-Fan Zhong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
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GraDeR: Membrane Protein Complex Preparation for Single-Particle Cryo-EM. Structure 2015; 23:1769-1775. [DOI: 10.1016/j.str.2015.06.029] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 12/21/2022]
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Wu D, Fan L, Xu C, Liu Z, Zhang Y, Liu L, Wang Q, Tao L. GJIC Enhances the phototoxicity of photofrin-mediated photodynamic treatment by the mechanisms related with ROS and Calcium pathways. JOURNAL OF BIOPHOTONICS 2015; 8:764-774. [PMID: 25597481 DOI: 10.1002/jbio.201400131] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 11/28/2014] [Accepted: 11/30/2014] [Indexed: 06/04/2023]
Abstract
Despite initially positive responses, recurrences after Photodynamic treatment (PDT) can occur and there is need for improvement in the effectiveness of PDT. Our study uniquely showed that there was a significantly gap junctional intercellular communication (GJIC)-dependent PDT cytotoxicity. The presence of GJIC composed of Connexin 32 increased the PDT phototoxicity in transfected HeLa cells and in the xenograft tumors, and the enhanced phototoxicity of Photofrin-mediated PDT by GJIC was related with ROS and calcium pathways. Our study indicates the possibility that up-regulation or maintenance of gap junction functionality may be used to increase the efficacy of PDT. The phototoxicity effect of Photofrin was substantially greater in Dox-treated cells, which expressed the Cx32 and formed the GJ, than Dox-untreated.
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Affiliation(s)
- Dengpan Wu
- Department of Pharmacology, Pharmacy School of Xuzhou Medical College, 221004, Xuzhou, P.R. China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Pharmacy School of Xuzhou Medical College, 221004, Xuzhou, P.R. China
| | - Lixia Fan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, P.R. China
| | - Chengfang Xu
- Department of Gynaecology and Obstetrics, the Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510080, P.R. China
| | - Zhen Liu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, P.R. China
| | - Yuan Zhang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, P.R. China
| | - Lucy Liu
- Department of Cell & Systems Biology, University of Toronto, Ontario, M5S3G5, Canada
| | - Qin Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, P.R. China.
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2nd Road, Guangzhou, 510080, P.R. China
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Localization and quantitative analysis of Cx43 in porcine oocytes during in vitro maturation. ZYGOTE 2015; 24:364-70. [DOI: 10.1017/s0967199415000271] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
SummaryMany studies of the main gap junction protein, Cx43, have been conducted in porcine oocyte research, but they have been limited to investigations of cumulus–oocyte complexes (COCs). In this study, we verified Cx43 not in COCs, but in porcine oocytes during maturation, and conducted a quantitative time course analysis. The location and dynamics of Cx43 were examined by immunocytochemistry and western blotting, respectively. COCs were cultured in NCSU23 medium and processed for immunocytochemistry and western blotting at 0, 14, 28, and 42 h after denuding. A Cx43 signal was detected on oolemmas, transzonal projections and the surface of zona pellucidae. Western blotting showed that Cx43 band density increased from 0 to 14 h, and gradually decreased thereafter. Our results clarified that Cx43 is localized in the ooplasmic membrane through zona pellucidae and its level changes over time during culture in porcine oocytes.
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Zonta F, Girotto G, Buratto D, Crispino G, Morgan A, Abdulhadi K, Alkowari M, Badii R, Gasparini P, Mammano F. The p.Cys169Tyr variant of connexin 26 is not a polymorphism. Hum Mol Genet 2015; 24:2641-8. [PMID: 25628337 PMCID: PMC4383868 DOI: 10.1093/hmg/ddv026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/21/2015] [Indexed: 12/31/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes the gap junction protein connexin 26 (Cx26), are the primary cause of hereditary prelingual hearing impairment. Here, the p.Cys169Tyr missense mutation of Cx26 (Cx26C169Y), previously classified as a polymorphism, has been identified as causative of severe hearing loss in two Qatari families. We have analyzed the effect of this mutation using a combination of confocal immunofluorescence microscopy and molecular dynamics simulations. At the cellular level, our results show that the mutant protein fails to form junctional channels in HeLa transfectants despite being correctly targeted to the plasma membrane. At the molecular level, this effect can be accounted for by disruption of the disulfide bridge that Cys169 forms with Cys64 in the wild-type structure (Cx26WT). The lack of the disulfide bridge in the Cx26C169Y protein causes a spatial rearrangement of two important residues, Asn176 and Thr177. In the Cx26WT protein, these residues play a crucial role in the intra-molecular interactions that permit the formation of an intercellular channel by the head-to-head docking of two opposing hemichannels resident in the plasma membrane of adjacent cells. Our results elucidate the molecular pathogenesis of hereditary hearing loss due to the connexin mutation and facilitate the understanding of its role in both healthy and affected individuals.
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Affiliation(s)
- Francesco Zonta
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy
| | - Giorgia Girotto
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy
| | - Damiano Buratto
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy
| | - Giulia Crispino
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy
| | - Anna Morgan
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy
| | - Khalid Abdulhadi
- Audiology and Balance Unit, National Program for Early Detection of Hearing Loss, WH, Hamad Medical Corporation (HMC) Doha, Doha, Qatar
| | - Moza Alkowari
- Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar
| | - Ramin Badii
- Molecular Genetics Laboratory, Department of Laboratory of Medicine and Pathology, Hamad Medical Corporation (HMC), Doha, Qatar
| | - Paolo Gasparini
- Department of Medical, Surgical and Health Sciences, University of Trieste, 34100 Trieste, Italy, Medical Genetics, Institute for Maternal and Child Health-IRCCS 'Burlo Garofolo', Trieste, Italy and
| | - Fabio Mammano
- Dipartimento di Fisica e Astronomia 'G. Galilei', Università di Padova, 35131 Padova, Italy, Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, 35129 Padova, Italy, CNR Institute of Cell Biology and Neurobiology, 00015 Monterotondo, Rome, Italy
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