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Mira-Osuna M, Borgne RL. Assembly, dynamics and remodeling of epithelial cell junctions throughout development. Development 2024; 151:dev201086. [PMID: 38205947 DOI: 10.1242/dev.201086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Cell junctions play key roles in epithelial integrity. During development, when epithelia undergo extensive morphogenesis, these junctions must be remodeled in order to maintain mechanochemical barriers and ensure the cohesion of the tissue. In this Review, we present a comprehensive and integrated description of junctional remodeling mechanisms in epithelial cells during development, from embryonic to adult epithelia. We largely focus on Drosophila, as quantitative analyses in this organism have provided a detailed characterization of the molecular mechanisms governing cell topologies, and discuss the conservation of these mechanisms across metazoans. We consider how changes at the molecular level translate to tissue-scale irreversible deformations, exploring the composition and assembly of cellular interfaces to unveil how junctions are remodeled to preserve tissue homeostasis during cell division, intercalation, invagination, ingression and extrusion.
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Affiliation(s)
- Marta Mira-Osuna
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes, CNRS UMR 6290, F-35000 Rennes, France
| | - Roland Le Borgne
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes, CNRS UMR 6290, F-35000 Rennes, France
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2
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Márquez M, Muñoz M, Córdova A, Puebla M, Figueroa XF. Connexin 40-Mediated Regulation of Systemic Circulation and Arterial Blood Pressure. J Vasc Res 2023; 60:87-100. [PMID: 37331352 DOI: 10.1159/000531035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/05/2023] [Indexed: 06/20/2023] Open
Abstract
Vascular system is a complex network in which different cell types and vascular segments must work in concert to regulate blood flow distribution and arterial blood pressure. Although paracrine/autocrine signaling is involved in the regulation of vasomotor tone, direct intercellular communication via gap junctions plays a central role in the control and coordination of vascular function in the microvascular network. Gap junctions are made up by connexin (Cx) proteins, and among the four Cxs expressed in the cardiovascular system (Cx37, Cx40, Cx43, and Cx45), Cx40 has emerged as a critical signaling pathway in the vessel wall. This Cx is predominantly found in the endothelium, but it is involved in the development of the cardiovascular system and in the coordination of endothelial and smooth muscle cell function along the length of the vessels. In addition, Cx40 participates in the control of vasomotor tone through the transmission of electrical signals from the endothelium to the underlying smooth muscle and in the regulation of arterial blood pressure by renin-angiotensin system in afferent arterioles. In this review, we discuss the participation of Cx40-formed channels in the development of cardiovascular system, control and coordination of vascular function, and regulation of arterial blood pressure.
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Affiliation(s)
- Mónica Márquez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Matías Muñoz
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexandra Córdova
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mariela Puebla
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Xavier F Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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3
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Connexin Mutations and Hereditary Diseases. Int J Mol Sci 2022; 23:ijms23084255. [PMID: 35457072 PMCID: PMC9027513 DOI: 10.3390/ijms23084255] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/04/2022] [Accepted: 04/09/2022] [Indexed: 02/01/2023] Open
Abstract
Inherited diseases caused by connexin mutations are found in multiple organs and include hereditary deafness, congenital cataract, congenital heart diseases, hereditary skin diseases, and X-linked Charcot–Marie–Tooth disease (CMT1X). A large number of knockout and knock-in animal models have been used to study the pathology and pathogenesis of diseases of different organs. Because the structures of different connexins are highly homologous and the functions of gap junctions formed by these connexins are similar, connexin-related hereditary diseases may share the same pathogenic mechanism. Here, we analyze the similarities and differences of the pathology and pathogenesis in animal models and find that connexin mutations in gap junction genes expressed in the ear, eye, heart, skin, and peripheral nerves can affect cellular proliferation and differentiation of corresponding organs. Additionally, some dominant mutations (e.g., Cx43 p.Gly60Ser, Cx32 p.Arg75Trp, Cx32 p.Asn175Asp, and Cx32 p.Arg142Trp) are identified as gain-of-function variants in vivo, which may play a vital role in the onset of dominant inherited diseases. Specifically, patients with these dominant mutations receive no benefits from gene therapy. Finally, the complete loss of gap junctional function or altered channel function including permeability (ions, adenosine triphosphate (ATP), Inositol 1,4,5-trisphosphate (IP3), Ca2+, glucose, miRNA) and electric activity are also identified in vivo or in vitro.
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4
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Valiunas V, White TW. Connexin43 and connexin50 channels exhibit different permeability to the second messenger inositol triphosphate. Sci Rep 2020; 10:8744. [PMID: 32457413 PMCID: PMC7251084 DOI: 10.1038/s41598-020-65761-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/07/2020] [Indexed: 11/12/2022] Open
Abstract
Gap junction channels made of different connexins have distinct permeability to second messengers, which could affect many cell processes, including lens epithelial cell division. Here, we have compared the permeability of IP3 and Ca2+ through channels made from two connexins, Cx43 and Cx50, that are highly expressed in vertebrate lens epithelial cells. Solute transfer was measured while simultaneously monitoring junctional conductance via dual whole-cell/perforated patch clamp. HeLa cells expressing Cx43 or Cx50 were loaded with Fluo-8, and IP3 or Ca2+ were delivered via patch pipette to one cell of a pair, or to a monolayer while fluorescence intensity changes were recorded. Cx43 channels were permeable to IP3 and Ca2+. Conversely, Cx50 channels were impermeable to IP3, while exhibiting high permeation of Ca2+. Reduced Cx50 permeability to IP3 could play a role in regulating cell division and homeostasis in the lens.
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Affiliation(s)
- Virginijus Valiunas
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA
| | - Thomas W White
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA.
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5
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Zhong C, Chang H, Wu Y, Zhou L, Wang Y, Wang M, Wu P, Qi Z, Zou J. Up-regulated Cx43 phosphorylation at Ser368 prolongs QRS duration in myocarditis. J Cell Mol Med 2018; 22:3537-3547. [PMID: 29664174 PMCID: PMC6010859 DOI: 10.1111/jcmm.13631] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 03/14/2018] [Indexed: 01/26/2023] Open
Abstract
Prolongation of QRS duration in electrocardiogram is one of the risk factors for morbidity and mortality in many kinds of cardiac diseases. However, its molecular mechanism is unknown. In this study, utilizing experimental autoimmune myocarditis (EAM) as a disease model, we show that the prolongation of QRS duration is accompanied by elevated phosphorylation of connexin 43 (Cx43) at Ser368 (pS368Cx43). In cultured cells, inflammatory cytokine IL‐1β activates p38 MAPK to up‐regulate pS368Cx43 and impairs cell‐to‐cell communication. In isolated hearts of normal rats, perfusion of IL‐1β not only increases pS368Cx43 but also impairs cell‐to‐cell communication and prolongs QRS duration. Furthermore, blockade of p38 MAPK down‐regulates pS368Cx43, improves cell‐to‐cell communication and reduces QRS duration in EAM. These findings suggest that up‐regulation of pS368Cx43 by IL‐1β via p38 MAPK contributes to the prolongation of QRS duration and could be a therapeutic target for myocarditis‐induced prolongation of QRS duration.
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Affiliation(s)
- Chunlian Zhong
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
| | - He Chang
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China.,Department of Cardiology, Affiliated Cardiovascular Hospital of Xiamen University, Xiamen, China
| | - Yang Wu
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China.,Department of Cardiology, Affiliated Cardiovascular Hospital of Xiamen University, Xiamen, China
| | - Li Zhou
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
| | - Yan Wang
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China.,Department of Cardiology, Affiliated Cardiovascular Hospital of Xiamen University, Xiamen, China
| | - Mingyan Wang
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
| | - Peng Wu
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
| | - Zhi Qi
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
| | - Jun Zou
- Department of Basic Medical Sciences, Medical College of Xiamen University, Xiamen, China
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6
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Kibschull M, Gellhaus A, Carette D, Segretain D, Pointis G, Gilleron J. Physiological roles of connexins and pannexins in reproductive organs. Cell Mol Life Sci 2015; 72:2879-98. [PMID: 26100514 PMCID: PMC11114083 DOI: 10.1007/s00018-015-1965-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 06/11/2015] [Indexed: 12/15/2022]
Abstract
Reproductive organs are complex and well-structured tissues essential to perpetuate the species. In mammals, the male and female reproductive organs vary on their organization, morphology and function. Connectivity between cells in such tissues plays pivotal roles in organogenesis and tissue functions through the regulation of cellular proliferation, migration, differentiation and apoptosis. Connexins and pannexins can be seen as major regulators of these physiological processes. In the present review, we assembled several lines of evidence demonstrating that these two families of proteins are essential for male and female reproduction.
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Affiliation(s)
- Mark Kibschull
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 25 Orde Street, Toronto, M5T 3H7 Canada
| | - Alexandra Gellhaus
- Department of Gynecology and Obstetrics, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
| | - Diane Carette
- UMR S1147, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
- University of Versailles, 78035 Saint Quentin, France
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
| | - Dominique Segretain
- UMR S1147, University Paris Descartes, 45 rue des Saints-Pères, 75006 Paris, France
- University of Versailles, 78035 Saint Quentin, France
| | - Georges Pointis
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
| | - Jerome Gilleron
- INSERM U 1065, University of Nice Sophia-Antipolis, 151 Route Saint-Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex 3, France
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7
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Bultmann-Mellin I, Conradi A, Maul AC, Dinger K, Wempe F, Wohl AP, Imhof T, Wunderlich FT, Bunck AC, Nakamura T, Koli K, Bloch W, Ghanem A, Heinz A, von Melchner H, Sengle G, Sterner-Kock A. Modeling autosomal recessive cutis laxa type 1C in mice reveals distinct functions for Ltbp-4 isoforms. Dis Model Mech 2015; 8:403-15. [PMID: 25713297 PMCID: PMC4381339 DOI: 10.1242/dmm.018960] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/16/2015] [Indexed: 01/03/2023] Open
Abstract
Recent studies have revealed an important role for LTBP-4 in elastogenesis. Its mutational inactivation in humans causes autosomal recessive cutis laxa type 1C (ARCL1C), which is a severe disorder caused by defects of the elastic fiber network. Although the human gene involved in ARCL1C has been discovered based on similar elastic fiber abnormalities exhibited by mice lacking the short Ltbp-4 isoform (Ltbp4S(-/-)), the murine phenotype does not replicate ARCL1C. We therefore inactivated both Ltbp-4 isoforms in the mouse germline to model ARCL1C. Comparative analysis of Ltbp4S(-/-) and Ltbp4-null (Ltbp4(-/-)) mice identified Ltbp-4L as an important factor for elastogenesis and postnatal survival, and showed that it has distinct tissue expression patterns and specific molecular functions. We identified fibulin-4 as a previously unknown interaction partner of both Ltbp-4 isoforms and demonstrated that at least Ltbp-4L expression is essential for incorporation of fibulin-4 into the extracellular matrix (ECM). Overall, our results contribute to the current understanding of elastogenesis and provide an animal model of ARCL1C.
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Affiliation(s)
- Insa Bultmann-Mellin
- Center for Experimental Medicine, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Anne Conradi
- Center for Experimental Medicine, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Alexandra C Maul
- Center for Experimental Medicine, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Katharina Dinger
- Center for Experimental Medicine, Medical Faculty, University of Cologne, 50931 Cologne, Germany. Department of Pediatrics and Adolescent Medicine, Medical Faculty, University of Cologne, 50937 Cologne, Germany
| | - Frank Wempe
- Department of Molecular Hematology, University of Frankfurt Medical School, 60590 Frankfurt am Main, Germany
| | - Alexander P Wohl
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Thomas Imhof
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany. Institute for Dental Research and Oral Musculoskeletal Biology, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - F Thomas Wunderlich
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany. Max Planck Institute for Metabolism Research, 50931 Cologne, Germany. Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Alexander C Bunck
- Department of Radiology, Medical Faculty, University of Cologne, 50937 Cologne, Germany
| | - Tomoyuki Nakamura
- Department of Pharmacology, Kansai Medical University, Osaka 570-8506, Japan
| | - Katri Koli
- Research Programs Unit and Transplantation Laboratory, Haartman Institute, University of Helsinki, 00014 Helsinki, Finland
| | - Wilhelm Bloch
- Institute of Cardiology and Sports Medicine, German Sport University Cologne, 50933 Cologne, Germany
| | - Alexander Ghanem
- Department of Medicine/Cardiology, University of Bonn, 53127 Bonn, Germany
| | - Andrea Heinz
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Harald von Melchner
- Department of Molecular Hematology, University of Frankfurt Medical School, 60590 Frankfurt am Main, Germany
| | - Gerhard Sengle
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany. Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Anja Sterner-Kock
- Center for Experimental Medicine, Medical Faculty, University of Cologne, 50931 Cologne, Germany.
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8
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Araújo AC, Marques S, Belo JA. Targeted inactivation of Cerberus like-2 leads to left ventricular cardiac hyperplasia and systolic dysfunction in the mouse. PLoS One 2014; 9:e102716. [PMID: 25033293 PMCID: PMC4102536 DOI: 10.1371/journal.pone.0102716] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/23/2014] [Indexed: 11/29/2022] Open
Abstract
Previous analysis of the Cerberus like 2 knockout (Cerl2−/−) mouse revealed a significant mortality during the first day after birth, mostly due to cardiac defects apparently associated with randomization of the left-right axis. We have however, identified Cerl2-associated cardiac defects, particularly a large increase in the left ventricular myocardial wall in neonates that cannot be explained by laterality abnormalities. Therefore, in order to access the endogenous role of Cerl2 in cardiogenesis, we analyzed the embryonic and neonatal hearts of Cerl2 null mutants that did not display a laterality phenotype. Neonatal mutants obtained from the compound mouse line Cer2−/−::Mlc1v-nLacZ24+, in which the pulmonary ventricle is genetically marked, revealed a massive enlargement of the ventricular myocardium in animals without laterality defects. Echocardiography analysis in Cerl2−/− neonates showed a left ventricular systolic dysfunction that is incompatible with a long lifespan. We uncovered that the increased ventricular muscle observed in Cerl2−/− mice is caused by a high cardiomyocyte mitotic index in the compact myocardium which is mainly associated with increased Ccnd1 expression levels in the left ventricle at embryonic day (E) 13. Interestingly, at this stage we found augmented left ventricular expression of Cerl2 levels when compared with the right ventricle, which may elucidate the regionalized contribution of Cerl2 to the left ventricular muscle formation. Importantly, we observed an increase of phosphorylated Smad2 (pSmad2) levels in embryonic (E13) and neonatal hearts indicating a prolonged TGFβs/Nodal-signaling activation. Concomitantly, we detected an increase of Baf60c levels, but only in Cerl2−/− embryonic hearts. These results indicate that independently of its well-known role in left-right axis establishment Cerl2 plays an important role during heart development in the mouse, mediating Baf60c levels by exerting an important control of the TGFβs/Nodal-signaling pathway.
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Affiliation(s)
- Ana Carolina Araújo
- Laboratory of Embryology and Genetic Manipulation, Regenerative Medicine Program, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- IBB - Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- PhD Program in Biomedical Sciences, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Sara Marques
- Laboratory of Embryology and Genetic Manipulation, Regenerative Medicine Program, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- IBB - Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - José António Belo
- Laboratory of Embryology and Genetic Manipulation, Regenerative Medicine Program, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- IBB - Institute for Biotechnology and Bioengineering, Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- CEDOC – Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
- * E-mail:
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Nielsen MS, Axelsen LN, Sorgen PL, Verma V, Delmar M, Holstein-Rathlou NH. Gap junctions. Compr Physiol 2013; 2:1981-2035. [PMID: 23723031 DOI: 10.1002/cphy.c110051] [Citation(s) in RCA: 289] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease.
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Affiliation(s)
- Morten Schak Nielsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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10
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Verheule S, Kaese S. Connexin diversity in the heart: insights from transgenic mouse models. Front Pharmacol 2013; 4:81. [PMID: 23818881 PMCID: PMC3694209 DOI: 10.3389/fphar.2013.00081] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/04/2013] [Indexed: 11/13/2022] Open
Abstract
Cardiac conduction is mediated by gap junction channels that are formed by connexin (Cx) protein subunits. The connexin family of proteins consists of more than 20 members varying in their biophysical properties and ability to combine with other connexins into heteromeric gap junction channels. The mammalian heart shows regional differences both in connexin expression profile and in degree of electrical coupling. The latter reflects functional requirements for conduction velocity which needs to be low in the sinoatrial and atrioventricular nodes and high in the ventricular conduction system. Over the past 20 years knowledge of the biology of gap junction channels and their role in the genesis of cardiac arrhythmias has increased enormously. This review focuses on the insights gained from transgenic mouse models. The mouse heart expresses Cx30, 30.2, 37, 40, 43, 45, and 46. For these connexins a variety of knock-outs, heart-specific knock-outs, conditional knock-outs, double knock-outs, knock-ins and overexpressors has been studied. We discuss the cardiac phenotype in these models and compare Cx expression between mice and men. Mouse models have enhanced our understanding of (patho)-physiological implications of Cx diversity in the heart. In principle connexin-specific modulation of electrical coupling in the heart represents an interesting treatment strategy for cardiac arrhythmias and conduction disorders.
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Affiliation(s)
- Sander Verheule
- Department of Physiology, Faculty of Medicine, Maastricht University Maastricht, Netherlands
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11
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Curti S, Hoge G, Nagy JI, Pereda AE. Synergy between electrical coupling and membrane properties promotes strong synchronization of neurons of the mesencephalic trigeminal nucleus. J Neurosci 2012; 32:4341-59. [PMID: 22457486 PMCID: PMC3339267 DOI: 10.1523/jneurosci.6216-11.2012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 01/06/2023] Open
Abstract
Electrical synapses are known to form networks of extensively coupled neurons in various regions of the mammalian brain. The mesencephalic trigeminal (MesV) nucleus, formed by the somata of primary afferents originating in jaw-closing muscles, constitutes one of the first examples supporting the presence of electrical synapses in the mammalian CNS; however, the properties, functional organization, and developmental emergence of electrical coupling within this structure remain unknown. By combining electrophysiological, tracer coupling, and immunochemical analysis in brain slices of rat and mouse, we found that coupling is mostly restricted to pairs or small clusters of MesV neurons. Electrical transmission is supported by connexin36 (Cx36)-containing gap junctions at somato-somatic contacts where only a small proportion of channels appear to be open (∼0.1%). In marked contrast with most brain structures, coupling among MesV neurons increases with age, such that it is absent during early development and appears at postnatal day 8. Interestingly, the development of coupling parallels the development of intrinsic membrane properties responsible for repetitive firing in these neurons. We found that, acting together, sodium and potassium conductances enhance the transfer of signals with high-frequency content via electrical synapses, leading to strong spiking synchronization of the coupled neurons. Together, our data indicate that coupling in the MesV nucleus is restricted to mostly pairs of somata between which electrical transmission is supported by a surprisingly small fraction of the channels estimated to be present, and that coupling synergically interacts with specific membrane conductances to promote synchronization of these neurons.
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Affiliation(s)
- Sebastian Curti
- Laboratorio de Neurofisiología Celular, Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo 11800, Uruguay.
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12
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Bedner P, Steinhäuser C, Theis M. Functional redundancy and compensation among members of gap junction protein families? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1971-84. [PMID: 22044799 DOI: 10.1016/j.bbamem.2011.10.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 10/08/2011] [Accepted: 10/17/2011] [Indexed: 12/15/2022]
Abstract
Gap junctions are intercellular conduits for small molecules made up by protein subunits called connexins. A large number of connexin genes were found in mouse and man, and most cell types express several connexins, lending support to the view that redundancy and compensation among family members exist. This review gives an overview of the current knowledge on redundancy and functional compensation - or lack thereof. It takes into account the different properties of connexin subunits which comprise gap junctional intercellular channels, but also the compatibility of connexins in gap junctions. Most insight has been gained by the investigation of mice deficient for one or more connexins and transgenic mice with functional replacement of one connexin gene by another. Most single deficient mice show phenotypical alterations limited to critical developmental time points or to specific organs and tissues, while mice doubly deficient for connexins expressed in the same cell type usually show more severe phenotypical alterations. Replacement of a connexin by another connexin in some cases gave rise to rescue of phenotypical alterations of connexin deficiencies, which were restricted to specific tissues. In many tissues, connexin substitution did not restore phenotypical alterations of connexin deficiencies, indicating that connexins are specialized in function. In some cases, fatal consequences arose from the replacement. The current consensus gained from such studies is that redundancy and compensation among connexins exists at least to a limited extent. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Abstract
Polydnaviruses are double-stranded DNA viruses associated with some subfamilies of ichneumonoid parasitoid wasps. Polydnavirus virions are delivered during wasp parasitization of a host, and virus gene expression in the host induces alterations of host physiology. Infection of susceptible host caterpillars by the polydnavirus Campoletis sonorensis ichnovirus (CsIV) leads to expression of virus genes, resulting in immune and developmental disruptions. CsIV carries four homologues of insect gap junction genes (innexins) termed vinnexins, which are expressed in multiple tissues of infected caterpillars. Previously, we demonstrated that two of these, VinnexinD and VinnexinG, form functional gap junctions in paired Xenopus oocytes. Here we show that VinnexinQ1 and VinnexinQ2, likewise, form junctions in this heterologous system. Moreover, we demonstrate that the vinnexins interact differentially with the Innexin2 orthologue of an ichnovirus host, Spodoptera frugiperda. Cell pairs coexpressing a vinnexin and Innexin2 or pairs in which one cell expresses a vinnexin and the neighboring cell Innexin2 assemble functional junctions with properties that differ from those of junctions composed of Innexin2 alone. These data suggest that altered gap junctional intercellular communication may underlie certain cellular pathologies associated with ichnovirus infection of caterpillar hosts.
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Abstract
Gap junctions (GJ) can no longer be thought of as simple channel forming structures that mediate intercellular communication. Hemi-channel and channel-independent functions of connexins (Cxs) have been described and numerous Cx interacting partners have been uncovered ranging from enzymes to structural and scaffolding molecules to transcription factors. With the growing number of Cx partners and functions, including well-documented roles for Cxs as conditional tumor suppressors, it has become essential to understand how Cxs are regulated in a context-dependent manner to mediate distinct functions. In this review we will shed light on the tissue and context-dependent regulation and function of Cxs and on the importance of Cx-interactions in modulating tissue-specific function. We will emphasize how the context-dependent functions of Cxs can help in understanding the impact of Cx mis-expression on cancer development and, ultimately, explore whether Cxs can be used as potential therapeutic targets in cancer treatment. In the end, we will address the need for developing relevant assays for studying Cx and GJ functions and will highlight how advances in bioengineering tools and the design of 3D biological platforms can help studying gap junction function in real time in a non-intrusive manner.
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Affiliation(s)
- R M Mroue
- Division of Life Sciences, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA
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15
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Frank M, Eiberger B, Janssen-Bienhold U, de Sevilla Müller LP, Tjarks A, Kim JS, Maschke S, Dobrowolski R, Sasse P, Weiler R, Fleischmann BK, Willecke K. Neuronal connexin-36 can functionally replace connexin-45 in mouse retina but not in the developing heart. J Cell Sci 2010; 123:3605-15. [PMID: 20930146 DOI: 10.1242/jcs.068668] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The gap junction protein connexin-45 (Cx45) is expressed in the conduction system of the heart and in certain neurons of the retina and brain. General and cardiomyocyte-directed deficiencies of Cx45 in mice lead to lethality on embryonic day 10.5 as a result of cardiovascular defects. Neuron-directed deletion of Cx45 leads to defects in transmission of visual signals. Connexin-36 (Cx36) is co-expressed with Cx45 in certain types of retinal interneurons. To determine whether these two connexins have similar functions and whether Cx36 can compensate for Cx45, we generated knock-in mice in which DNA encoding Cx45 was replaced with that encoding Cx36. Neuron-directed replacement of Cx45 with Cx36 resulted in viable animals. Electroretinographic and neurotransmitter coupling analyses demonstrated functional compensation in the retina. By contrast, general and cardiomyocyte-directed gene replacement led to lethality on embryonic day 11.5. Mutant embryos displayed defects in cardiac morphogenesis and conduction. Thus, functional compensation of Cx45 by Cx36 did not occur during embryonic heart development. These data suggest that Cx45 and Cx36 have similar functions in the retina, whereas Cx45 fulfills special functions in the developing heart that cannot be compensated by Cx36.
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Affiliation(s)
- Marina Frank
- Institute of Genetics, University of Bonn, 53117 Bonn, Germany
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16
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Abstract
Gap junctions are aggregates of intercellular channels that permit direct cell-cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology.
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17
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Chaible LM, Corat MA, Abdelhay E, Dagli MLZ. Genetically modified animals for use in research and biotechnology. GENETICS AND MOLECULAR RESEARCH 2010; 9:1469-82. [PMID: 20677136 DOI: 10.4238/vol9-3gmr867] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Transgenic animals are used extensively in the study of in vivo gene function, as models for human diseases and in the production of biopharmaceuticals. The technology behind obtaining these animals involves molecular biology techniques, cell culture and embryo manipulation; the mouse is the species most widely used as an experimental model. In scientific research, diverse models are available as tools for the elucidation of gene function, such as transgenic animals, knockout and conditional knockout animals, knock-in animals, humanized animals, and knockdown animals. We examined the evolution of the science for the development of these animals, as well as the techniques currently used in obtaining these animal models. We review the phenotypic techniques used for elucidation of alterations caused by genetic modification. We also investigated the role of genetically modified animals in the biotechnology industry, where they promise a revolution in obtaining heterologous proteins through natural secretions, such as milk, increasing the scale of production and facilitating purification, thereby lowering the cost of production of hormones, growth factors and enzymes.
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Affiliation(s)
- L M Chaible
- Laboratório de Oncologia Experimental, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, SP, Brasil
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18
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Salilew-Wondim D, Hölker M, Rings F, Ghanem N, Ulas-Cinar M, Peippo J, Tholen E, Looft C, Schellander K, Tesfaye D. Bovine pretransfer endometrium and embryo transcriptome fingerprints as predictors of pregnancy success after embryo transfer. Physiol Genomics 2010; 42:201-18. [PMID: 20388838 DOI: 10.1152/physiolgenomics.00047.2010] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aberrant gene expression in the uterine endometrium and embryo has been the major causes of pregnancy failure in cattle. However, selecting cows having adequate endometrial receptivity and embryos of better developmental competence based on the gene expression pattern has been a greater challenge. To investigate whether pretransfer endometrial and embryo gene expression pattern has a direct relation with upcoming pregnancy success, we performed a global endometrial and embryo transcriptome analysis using endometrial and embryo biopsy technology and the pregnancy outcome information. For this, endometrial samples were collected from Simmental heifers at day 7 and 14 of the estrous cycle, one cycle prior to embryo transfer. In the next cycle, blastocyst stage embryos were transferred to recipients at day 7 of the estrous cycle after taking 30-40% of the blastocyst as a biopsy for transcriptome analysis. The results revealed that at day 7 of the estrous cycle, the endometrial gene expression pattern of heifers whose pregnancy resulting in calf delivery was significantly different compared with those resulting in no pregnancy. These differences were accompanied by qualitative and quantitative alteration of major biological process and molecular pathways. However, the transcriptome difference was minimal between the two groups of animals at day 14 of the estrous cycle. Similarly, the transcriptome analysis between embryos biopsies that resulted in calf delivery and those resulted in no pregnancy revealed a total of 70 differentially expressed genes. Among these, the transcript levels of 32 genes including SPAG17, PF6, UBE2D3P, DFNB31, AMD1, DTNBP1, and ARL8B were higher in embryo biopsies resulting in calf delivery. Therefore, the present study highlights the potential of pretransfer endometrial and embryo gene expression patterns as predictors of pregnancy success in cattle.
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Affiliation(s)
- Dessie Salilew-Wondim
- Institute of Animal Science, Animal Breeding and Husbandry Group, University of Bonn, Endenicher Allee 15, Bonn, Germany
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Schweda F, Kurtz L, de Wit C, Janssen-Bienhold U, Kurtz A, Wagner C. Substitution of connexin40 with connexin45 prevents hyperreninemia and attenuates hypertension. Kidney Int 2009; 75:482-9. [PMID: 19109587 DOI: 10.1038/ki.2008.637] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Connexins (Cxs) are a family of transmembrane proteins that form gap junctions with unique and redundant biophysical functions. Juxtaglomerular cells express Cx40, which is crucial to the control of renin secretion by blood pressure and angiotensin II, and mice that lack Cx40 have high plasma renin and hypertension. To examine whether normal juxtaglomerular cell function depends on the unique properties of Cx40, we measured renin release in mice where the coding sequence for Cx40 was replaced by that for Cx45, using the knock-in method. We first found that the knock-in strategy indeed resulted in expression of Cx45 but not Cx40 in the juxtaglomerular cells of these mice. The plasma renin concentration of the knock-in mice was similar to that in wild-type mice. The high blood pressure of the Cx40 knockout mice was significantly reduced when Cx45 was knocked into the locus but remained mildly elevated compared to wild-type mice. Blockade of angiotensin II formation by enalapril increased the plasma renin concentration in wild-type and the Cx45 knock-in mice but not in the Cx40 knockout mice. Infusion of angiotensin II into isolated perfused kidneys results in decreased renin release, a phenomenon that was attenuated in the Cx40 knockout mice. However, in the Cx45 knock-in mice, angiotensin II suppressed renin release similar to its effect in wild type mice. Unilateral renal artery stenosis increased the plasma renin concentration and blood pressure in both the wild-type and the Cx45 knock-in mice but not in the Cx40 knockout mice. Since Cx40 can be replaced by Cx45, a connexin with a significantly lower conductivity, we suggest that the regulation of renin release is not dependent on the unique electrical properties of these channel proteins.
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Affiliation(s)
- Frank Schweda
- Institute of Physiology, University of Regensburg, Regensburg, Germany.
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20
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Abstract
Direct intercellular communication via gap junctions is critical in the control and coordination of vascular function. In the cardiovascular system, gap junctions are made up of one or more of four connexin proteins: Cx37, Cx40, Cx43, and Cx45. The expression of more than one gap-junction protein in the vasculature is not redundant. Rather, vascular connexins work in concert, first during the development of the cardiovascular system, and then in integrating smooth muscle and endothelial cell function, and in coordinating cell function along the length of the vessel wall. In addition, connexin-based channels have emerged as an important signaling pathway in the astrocyte-mediated neurovascular coupling. Direct electrical communication between endothelial cells and vascular smooth muscle cells via gap junctions is thought to play a relevant role in the control of vasomotor tone, providing the signaling pathway known as endothelium-derived hyperpolarizing factor (EDHF). Consistent with the importance of gap junctions in the regulation of vasomotor tone and arterial blood pressure, the expression of connexins is altered in diseases associated with vascular complications. In this review, we discuss the participation of connexin-based channels in the control of vascular function in physiologic and pathologic conditions, with a special emphasis on hypertension and diabetes.
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Affiliation(s)
- Xavier F Figueroa
- Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
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21
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Johnstone S, Isakson B, Locke D. Biological and biophysical properties of vascular connexin channels. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:69-118. [PMID: 19815177 PMCID: PMC2878191 DOI: 10.1016/s1937-6448(09)78002-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intercellular channels formed by connexin proteins play a pivotal role in the direct movement of ions and larger cytoplasmic solutes between vascular endothelial cells, between vascular smooth muscle cells, and between endothelial and smooth muscle cells. Multiple genetic and epigenetic factors modulate connexin expression levels and/or channel function, including cell-type-independent and cell-type-specific transcription factors, posttranslational modifications, and localized membrane targeting. Additionally, differences in protein-protein interactions, including those between connexins, significantly contribute to both vascular homeostasis and disease progression. The biophysical properties of the connexin channels identified in the vasculature, those formed by Cx37, Cx40, Cx43 and/or Cx45 proteins, are discussed in this chapter in the physiological and pathophysiological context of vessel function.
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Affiliation(s)
- Scott Johnstone
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 29908
| | - Brant Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 29908
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 29908
| | - Darren Locke
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103
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Kibschull M, Gellhaus A, Winterhager E. Analogous and unique functions of connexins in mouse and human placental development. Placenta 2008; 29:848-54. [PMID: 18783825 DOI: 10.1016/j.placenta.2008.07.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/22/2008] [Accepted: 07/31/2008] [Indexed: 01/20/2023]
Abstract
Here, we review the expression, localization and the possible role of the different connexin isoforms in placental function and development in mice and men. Connexin gene deletion in mice has shown that Cx26 is responsible for transplacental uptake of glucose in the labyrinth, and Cx31 as well as Cx31.1 for trophoblast cell lineage development. In the human placenta, it appears that Cx43 is required for the fusion process of cytotrophoblastic cells leading to the formation of the syncytiotrophoblast. Thus Cx26 and Cx43 serve different species-specific functions in the functionally analogous placental compartments, mouse labyrinth and human villous trophoblast. However, like Cx31 in the mouse, Cx40 plays a critical role in the switch from a proliferative to an invasive phenotype of the trophoblast cells invading the endometrium. Both connexin channels seem to have similar functions in analogous compartments of the placentas. Taken together, connexins are important in regulating trophoblast cell differentiation in both species. In mouse, connexin channels are specifically involved in passive transport of molecules across the placental barriers.
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Affiliation(s)
- M Kibschull
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Canada
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23
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Wölfle SE, Schmidt VJ, Hoepfl B, Gebert A, Alcoléa S, Gros D, de Wit C. Connexin45 cannot replace the function of connexin40 in conducting endothelium-dependent dilations along arterioles. Circ Res 2007; 101:1292-9. [PMID: 17932322 DOI: 10.1161/circresaha.107.163279] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Intercellular communication through gap junctions coordinates vascular tone by the conduction of vasomotor responses along the vessel wall. Gap junctions in arterioles are composed of different connexins (Cxs) (Cx40, Cx37, Cx45, Cx43), but it is unknown whether Cxs are interchangeable. We used mice with a targeted replacement of Cx40 by Cx45 (Cx40KI45) to explore whether Cx45 can functionally replace Cx40 in arterioles. Arterioles were locally stimulated using acetylcholine, bradykinin, adenosine, and K(+) in the cremaster of Cx40KI45, Cx40-deficient (Cx40ko), and wild-type mice, and diameter changes were assessed by intravital microscopy. Additionally, arterial pressure was measured by telemetry and Cx expression verified by immunofluorescence. Acetylcholine initiated a local dilation of a similar amplitude in all genotypes ( approximately 50%), which was rapidly conducted to upstream sites (1200 mum distance) without attenuation in wild type. In marked contrast, the remote dilation was significantly reduced in Cx40ko (25+/-3%) and Cx40KI45 (24+/-2%). Likewise, dilations initiated by bradykinin application were conducted without attenuation up to 1200 mum in wild type but not in Cx40ko and Cx40KI45. Adenosine-induced dilations and K(+)-induced constrictions were conducted similarly with decaying amplitude in all genotypes. Arterial pressure was strongly elevated in Cx40ko (161+/-1 versus 116+/-2 mm Hg) but only moderately in Cx40KI45 (133+/-8 mm Hg). This demonstrates that Cx40 function is critical for the conduction of acetylcholine and bradykinin dilations and cannot be substituted by Cx45. Therefore, unique properties of Cx40 are required for endothelial signal conduction, whereas nonspecific restoration of communication maintains additional functions related to blood pressure control.
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24
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Nilles KM, London B. Knockin Animal Models of Inherited Arrhythmogenic Diseases: What Have We Learned From Them? J Cardiovasc Electrophysiol 2007; 18:1117-25. [PMID: 17573834 DOI: 10.1111/j.1540-8167.2007.00884.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mouse models are becoming an increasingly accepted method of studying human diseases. Knockin and knockout techniques have several advantages over traditional transgenic overexpression, and the versatility of the knockin mouse allows the study of both gain of function mutations through targeted mutagenesis, as well as the replacement of one gene by another functional gene. Here, we will review the methods available to generate knockin mice; provide an overview of the techniques used to study electrophysiology in the mice at the cellular, organ, and whole animal level; and highlight knockin mice that have implications for inherited arrhythmias. Specifically, we will focus on models that used knockin mice to clarify gene expression, identify similarities and differences between related genes, and model human arrhythmia syndromes. Our goal is to provide the reader with a general understanding of studies done on knockin mouse models of inherited arrhythmias as well as ideas for future directions.
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Affiliation(s)
- Kathy M Nilles
- Cardiovascular Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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25
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Spray DC, Iacobas DA. Organizational principles of the connexin-related brain transcriptome. J Membr Biol 2007; 218:39-47. [PMID: 17657523 DOI: 10.1007/s00232-007-9049-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Accepted: 05/14/2007] [Indexed: 01/01/2023]
Abstract
We have found that deletion of genes encoding the gap junction proteins Cx43, Cx32 and Cx36 alter the expression levels of large numbers of genes in mouse brain located on all chromosomes and encoding proteins from all major functional categories. Gene regulation in Cx32 and Cx43 null brains was more similar than that in the Cx36 null brain, suggesting the possibility of transcriptomic controls exerted by both genes on both astrocytes and oligodendrocytes. In order to explore the nature of expression linkage among the genes, we examined coordinated expression patterns in wild-type and connexin null brains. Coordination with Cx43 in wild-type brain predicted regulation in Cx43 nulls with considerable accuracy. Moreover, interlinkage within gene networks was greatly perturbed in the Cx43 null brain. These findings suggest several principles regarding regulatory transcriptomic networks involving gap junction genes and raise the issue of the underlying cause of connexin null phenotypes as well as mechanisms of regulation.
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Affiliation(s)
- David C Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461, USA.
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26
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Replacement of connexin43 by connexin26 in transgenic mice leads to dysfunctional reproductive organs and slowed ventricular conduction in the heart. BMC DEVELOPMENTAL BIOLOGY 2007; 7:26. [PMID: 17408477 PMCID: PMC1852306 DOI: 10.1186/1471-213x-7-26] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 04/04/2007] [Indexed: 11/22/2022]
Abstract
Background In order to further distinguish unique from general functions of connexin43, we have generated mice in which the coding region of connexin43 was replaced by that of connexin26. Results Heterozygous mothers showed impaired mammary gland development responsible for decreased lactation and early postnatal death of the pups which could be partially rescued by wild type foster mothers. Only about 17% of the homozygous connexin43 knock-in connexin26 mice instead of 25% expected according to Mendelian inheritance, were born and only 6% survived to day 21 post partum and longer. Neonatal and adult connexin43 knock-in connexin26 mice exhibited slowed ventricular conduction in their hearts, i.e. similar but delayed electrophysiological abnormalities as connexin43 deficient mice. Furthermore, connexin43 knock-in connexin26 male and female mice were infertile and exhibited hypotrophic gonads. In testes, tubuli seminiferi were developed and spermatogonia as well as some primary spermatocytes were present, but further differentiated stages of spermatogenesis were absent. Ovaries of female connexin43 knock-in connexin26 mice revealed only few follicles and the maturation of follicles was completely impaired. Conclusion The impaired gametogenesis of homozygous males and females can explain their infertility.
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Affiliation(s)
- Xavier F Figueroa
- Unidad de Regulación Neurohumoral, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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