1
|
Simpson KE, Venkateshappa R, Pang ZK, Faizi S, Tibbits GF, Claydon TW. Utility of Zebrafish Models of Acquired and Inherited Long QT Syndrome. Front Physiol 2021; 11:624129. [PMID: 33519527 PMCID: PMC7844309 DOI: 10.3389/fphys.2020.624129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 01/12/2023] Open
Abstract
Long-QT Syndrome (LQTS) is a cardiac electrical disorder, distinguished by irregular heart rates and sudden death. Accounting for ∼40% of cases, LQTS Type 2 (LQTS2), is caused by defects in the Kv11.1 (hERG) potassium channel that is critical for cardiac repolarization. Drug block of hERG channels or dysfunctional channel variants can result in acquired or inherited LQTS2, respectively, which are typified by delayed repolarization and predisposition to lethal arrhythmia. As such, there is significant interest in clear identification of drugs and channel variants that produce clinically meaningful perturbation of hERG channel function. While toxicological screening of hERG channels, and phenotypic assessment of inherited channel variants in heterologous systems is now commonplace, affordable, efficient, and insightful whole organ models for acquired and inherited LQTS2 are lacking. Recent work has shown that zebrafish provide a viable in vivo or whole organ model of cardiac electrophysiology. Characterization of cardiac ion currents and toxicological screening work in intact embryos, as well as adult whole hearts, has demonstrated the utility of the zebrafish model to contribute to the development of therapeutics that lack hERG-blocking off-target effects. Moreover, forward and reverse genetic approaches show zebrafish as a tractable model in which LQTS2 can be studied. With the development of new tools and technologies, zebrafish lines carrying precise channel variants associated with LQTS2 have recently begun to be generated and explored. In this review, we discuss the present knowledge and questions raised related to the use of zebrafish as models of acquired and inherited LQTS2. We focus discussion, in particular, on developments in precise gene-editing approaches in zebrafish to create whole heart inherited LQTS2 models and evidence that zebrafish hearts can be used to study arrhythmogenicity and to identify potential anti-arrhythmic compounds.
Collapse
Affiliation(s)
- Kyle E. Simpson
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Ravichandra Venkateshappa
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Zhao Kai Pang
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Shoaib Faizi
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Glen F. Tibbits
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
- Department of Cardiovascular Science, British Columbia Children’s Hospital, Vancouver, BC, Canada
| | - Tom W. Claydon
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| |
Collapse
|
2
|
Rayani K, Lin E, Craig C, Lamothe M, Shafaattalab S, Gunawan M, Li AY, Hove-Madsen L, Tibbits GF. Zebrafish as a model of mammalian cardiac function: Optically mapping the interplay of temperature and rate on voltage and calcium dynamics. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 138:69-90. [DOI: 10.1016/j.pbiomolbio.2018.07.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 12/27/2022]
|
3
|
Chanson M, Watanabe M, O'Shaughnessy EM, Zoso A, Martin PE. Connexin Communication Compartments and Wound Repair in Epithelial Tissue. Int J Mol Sci 2018; 19:ijms19051354. [PMID: 29751558 PMCID: PMC5983803 DOI: 10.3390/ijms19051354] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/20/2022] Open
Abstract
Epithelial tissues line the lumen of tracts and ducts connecting to the external environment. They are critical in forming an interface between the internal and external environment and, following assault from environmental factors and pathogens, they must rapidly repair to maintain cellular homeostasis. These tissue networks, that range from a single cell layer, such as in airway epithelium, to highly stratified and differentiated epithelial surfaces, such as the epidermis, are held together by a junctional nexus of proteins including adherens, tight and gap junctions, often forming unique and localised communication compartments activated for localised tissue repair. This review focuses on the dynamic changes that occur in connexins, the constituent proteins of the intercellular gap junction channel, during wound-healing processes and in localised inflammation, with an emphasis on the lung and skin. Current developments in targeting connexins as corrective therapies to improve wound closure and resolve localised inflammation are also discussed. Finally, we consider the emergence of the zebrafish as a concerted whole-animal model to study, visualise and track the events of wound repair and regeneration in real-time living model systems.
Collapse
Affiliation(s)
- Marc Chanson
- Department of Pediatrics and Cell Physiology & Metabolism, Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland.
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, Osaka 565-0871, Japan.
| | - Erin M O'Shaughnessy
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| | - Alice Zoso
- Department of Pediatrics and Cell Physiology & Metabolism, Geneva University Hospitals and University of Geneva, 1211 Geneva, Switzerland.
| | - Patricia E Martin
- Department of Life Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK.
| |
Collapse
|
4
|
Burkhard S, van Eif V, Garric L, Christoffels VM, Bakkers J. On the Evolution of the Cardiac Pacemaker. J Cardiovasc Dev Dis 2017; 4:jcdd4020004. [PMID: 29367536 PMCID: PMC5715705 DOI: 10.3390/jcdd4020004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 01/26/2023] Open
Abstract
The rhythmic contraction of the heart is initiated and controlled by an intrinsic pacemaker system. Cardiac contractions commence at very early embryonic stages and coordination remains crucial for survival. The underlying molecular mechanisms of pacemaker cell development and function are still not fully understood. Heart form and function show high evolutionary conservation. Even in simple contractile cardiac tubes in primitive invertebrates, cardiac function is controlled by intrinsic, autonomous pacemaker cells. Understanding the evolutionary origin and development of cardiac pacemaker cells will help us outline the important pathways and factors involved. Key patterning factors, such as the homeodomain transcription factors Nkx2.5 and Shox2, and the LIM-homeodomain transcription factor Islet-1, components of the T-box (Tbx), and bone morphogenic protein (Bmp) families are well conserved. Here we compare the dominant pacemaking systems in various organisms with respect to the underlying molecular regulation. Comparative analysis of the pathways involved in patterning the pacemaker domain in an evolutionary context might help us outline a common fundamental pacemaker cell gene programme. Special focus is given to pacemaker development in zebrafish, an extensively used model for vertebrate development. Finally, we conclude with a summary of highly conserved key factors in pacemaker cell development and function.
Collapse
Affiliation(s)
- Silja Burkhard
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
| | - Vincent van Eif
- Department of Medical Biology, Academic Medical Center Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Laurence Garric
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
| | - Vincent M Christoffels
- Department of Medical Biology, Academic Medical Center Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Jeroen Bakkers
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands.
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Evolution and development of the building plan of the vertebrate heart. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:783-94. [PMID: 23063530 DOI: 10.1016/j.bbamcr.2012.10.004] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/01/2012] [Accepted: 10/03/2012] [Indexed: 12/11/2022]
Abstract
Early cardiac development involves the formation of a heart tube, looping of the tube and formation of chambers. These processes are highly similar among all vertebrates, which suggest the existence of evolutionary conservation of the building plan of the heart. From the jawless lampreys to man, T-box transcription factors like Tbx5 and Tbx20 are fundamental for heart formation, whereas Tbx2 and Tbx3 repress chamber formation on the sinu-atrial and atrioventricular borders. Also, electrocardiograms from different vertebrates are alike, even though the fish heart only has two chambers whereas the mammalian heart has four chambers divided by septa and in addition has much higher heart rates. We conclude that most features of the high-performance hearts of mammals and birds can be traced back to less developed traits in the hearts of ectothermic vertebrates. This article is part of a Special Issue entitled: Cardiomyocyte biology: Cardiac pathways of differentiation, metabolism and contraction.
Collapse
|
7
|
Tao L, DeRosa AM, White TW, Valdimarsson G. Zebrafish cx30.3: identification and characterization of a gap junction gene highly expressed in the skin. Dev Dyn 2011; 239:2627-36. [PMID: 20737512 DOI: 10.1002/dvdy.22399] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We have identified and characterized a zebrafish connexin, Cx30.3. Sequence similarity analyses suggested that Cx30.3 was orthologous to both mammalian Cx26 and Cx30, known to play important roles in the skin and inner ear of mammals. Analysis of mRNA expression showed that Cx30.3 was present in early embryos, and was highly abundant in skin, but also detected in other tissues including fins, inner ear, heart, and the retina. Injection of Cx30.3 cRNA into Xenopus oocytes elicited robust intercellular coupling with voltage gating sensitivity similar to mammalian Cx26 and Cx30. The similarities in functional properties and expression patterns suggest that Cx30.3, like mammalian Cx26 and Cx30, may play a significant role in skin development, hearing, and balance in zebrafish. Thus, zebrafish could potentially serve as an excellent model to study disorders of the skin and deafness that result from human connexin mutations.
Collapse
Affiliation(s)
- Liang Tao
- Department of Biological Sciences, University of Manitoba, Winnipeg, Canada
| | | | | | | |
Collapse
|
8
|
Robinson BW, Germano G, Song Y, Abrams J, Scott M, Guariento I, Tiso N, Argenton F, Basso G, Rhodes J, Kanki JP, Look AT, Balice-Gordon RJ, Felix CA. mll ortholog containing functional domains of human MLL is expressed throughout the zebrafish lifespan and in haematopoietic tissues. Br J Haematol 2010; 152:307-21. [PMID: 21155757 DOI: 10.1111/j.1365-2141.2010.08398.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Infant leukaemia is an embryonal disease in which the underlying MLL translocations initiate in utero. Zebrafish offer unique potential to understand how MLL impacts haematopoiesis from the earliest embryonic timepoints and how translocations cause leukaemia as an embryonal process. In this study, a zebrafish mll cDNA syntenic to human MLL spanning the 5' to 3' UTRs, was cloned from embryos, and mll expression was characterized over the zebrafish lifespan. The protein encoded by the 35-exon ORF exhibited 46·4% overall identity to human MLL and 68-100% conservation in functional domains (AT-hooks, SNL, CXXC, PHD, bromodomain, FYRN, taspase1 sites, FYRC, SET). Maternally supplied transcripts were detected at 0-2 hpf. Strong ubiquitous early zygotic expression progressed to a cephalo-caudal gradient during later embryogenesis. mll was expressed in the intermediate cell mass (ICM) where primitive erythrocytes are produced and in the kidney where definitive haematopoiesis occurs in adults. mll exhibits high cross species conservation, is developmentally regulated in haematopoietic and other tissues and is expressed from the earliest embryonic timepoints throughout the zebrafish lifespan. Haematopoietic tissue expression validates using zebrafish for MLL haematopoiesis and leukaemia models.
Collapse
Affiliation(s)
- Blaine W Robinson
- Division of Oncology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Tandem alternative splicing of zebrafish connexin45.6. Genomics 2010; 96:112-8. [PMID: 20466054 DOI: 10.1016/j.ygeno.2010.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/19/2010] [Accepted: 05/04/2010] [Indexed: 11/24/2022]
Abstract
Early studies suggested that most connexin genes share a relatively simple structure with a single intron of variable length interrupting the 5' untranslated region (UTR). Here we report that zebrafish cx45.6 shows six isoforms of alternative 5'UTRs which are generated from multiple promoter usage and alternative pre-mRNA splicing. Interestingly, cx45.6 undergoes tandem alternative splicing, which produces transcripts only differing by 3 nucleotides. This is the first study that has demonstrated tandem alternative pre-mRNA splicing in the connexin gene family. Expression patterns of cx45.6 alternative transcripts were demonstrated by real-time RT-PCR during zebrafish embryonic development and in adult tissues. The complexity of 5'UTR diversity suggests complicated regulatory mechanisms for cx45.6 gene expression at both transcriptional and post-transcriptional levels, and we propose that tandem alternative splicing in cx45.6 5'UTRs could play a role in translational control. These results lay groundwork for further investigations on the regulation and function of cx45.6 gene expression.
Collapse
|
10
|
Chi NC, Shaw RM, Jungblut B, Huisken J, Ferrer T, Arnaout R, Scott I, Beis D, Xiao T, Baier H, Jan LY, Tristani-Firouzi M, Stainier DYR. Genetic and physiologic dissection of the vertebrate cardiac conduction system. PLoS Biol 2008; 6:e109. [PMID: 18479184 PMCID: PMC2430899 DOI: 10.1371/journal.pbio.0060109] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 03/20/2008] [Indexed: 12/05/2022] Open
Abstract
Vertebrate hearts depend on highly specialized cardiomyocytes that form the cardiac conduction system (CCS) to coordinate chamber contraction and drive blood efficiently and unidirectionally throughout the organism. Defects in this specialized wiring system can lead to syncope and sudden cardiac death. Thus, a greater understanding of cardiac conduction development may help to prevent these devastating clinical outcomes. Utilizing a cardiac-specific fluorescent calcium indicator zebrafish transgenic line, Tg(cmlc2:gCaMP)(s878), that allows for in vivo optical mapping analysis in intact animals, we identified and analyzed four distinct stages of cardiac conduction development that correspond to cellular and anatomical changes of the developing heart. Additionally, we observed that epigenetic factors, such as hemodynamic flow and contraction, regulate the fast conduction network of this specialized electrical system. To identify novel regulators of the CCS, we designed and performed a new, physiology-based, forward genetic screen and identified for the first time, to our knowledge, 17 conduction-specific mutations. Positional cloning of hobgoblin(s634) revealed that tcf2, a homeobox transcription factor gene involved in mature onset diabetes of the young and familial glomerulocystic kidney disease, also regulates conduction between the atrium and the ventricle. The combination of the Tg(cmlc2:gCaMP)(s878) line/in vivo optical mapping technique and characterization of cardiac conduction mutants provides a novel multidisciplinary approach to further understand the molecular determinants of the vertebrate CCS.
Collapse
Affiliation(s)
- Neil C Chi
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Robin M Shaw
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
- Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Benno Jungblut
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Jan Huisken
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
| | - Tania Ferrer
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Rima Arnaout
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Ian Scott
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Dimitris Beis
- Developmental Biology, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Tong Xiao
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
- Programs in Neuroscience, Genetics, Human Genetics, and Developmental Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Herwig Baier
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
- Programs in Neuroscience, Genetics, Human Genetics, and Developmental Biology, University of California San Francisco, San Francisco, California, United States of America
| | - Lily Y Jan
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
- Department of Physiology, University of California San Francisco, San Francisco, California, United States of America
- Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Martin Tristani-Firouzi
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Didier Y. R Stainier
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics, and Human Genetics, University of California San Francisco, San Francisco, California, United States of America
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| |
Collapse
|
11
|
Watanabe M, Iwashita M, Ishii M, Kurachi Y, Kawakami A, Kondo S, Okada N. Spot pattern of leopard Danio is caused by mutation in the zebrafish connexin41.8 gene. EMBO Rep 2006; 7:893-7. [PMID: 16845369 PMCID: PMC1559663 DOI: 10.1038/sj.embor.7400757] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 06/20/2006] [Accepted: 06/20/2006] [Indexed: 11/08/2022] Open
Abstract
Leopard, a well-known zebrafish mutant that has a spotted skin pattern instead of stripes, is a model for the study of pigment patterning. To understand the mechanisms underlying stripe formation, as well as the spot variation observed in leopard, we sought to identify the gene responsible for this phenotype. Using positional cloning, we identified the leopard gene as an orthologue of the mammalian connexin 40 gene. A variety of different leopard alleles, such as leo(t1), leo(tq270) and leo(tw28), show different skin-pattern phenotypes. In this manuscript we show that the mutation in allele leo(t1) is a nonsense mutation, whereas alleles leo(tq270) and leo(tw28) contain the missense mutations I202F and I31F, respectively. Patch-clamp experiments of connexin hemichannels demonstrated that the I202F substitution in allele leo(tq270) disrupted the channel function of connexin41.8. These results demonstrate that mutations in this gene lead to a variety of leopard spot patterns.
Collapse
Affiliation(s)
- Masakatsu Watanabe
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B21, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Motoko Iwashita
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B21, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
- Center of Developmental Biology, Riken, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0077, Japan
| | - Masaru Ishii
- Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yoshihisa Kurachi
- Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Atsushi Kawakami
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B21, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
- Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shigeru Kondo
- Center of Developmental Biology, Riken, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0077, Japan
- Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - Norihiro Okada
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B21, Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
- National Institute for Basic Biology, Nishigonaka, Myodaiji, Okazaki 444-8585, Japan
| |
Collapse
|
12
|
Eastman SD, Chen THP, Falk MM, Mendelson TC, Iovine MK. Phylogenetic analysis of three complete gap junction gene families reveals lineage-specific duplications and highly supported gene classes. Genomics 2006; 87:265-74. [PMID: 16337772 DOI: 10.1016/j.ygeno.2005.10.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 10/14/2005] [Accepted: 10/17/2005] [Indexed: 11/17/2022]
Abstract
Gap junctions, composed of connexin proteins in chordates, are the most ubiquitous form of intercellular communication. Complete connexin gene families have been identified from human (20) and mouse (19), revealing significant diversity in gap junction channels. We searched current databases and identified 37 putative zebrafish connexin genes, almost twice the number found in mammals. Phylogenetic comparison of entire connexin gene families from human, mouse, and zebrafish revealed 23 zebrafish relatives of 16 mammalian connexins, and 14 connexins apparently unique to zebrafish. We found evidence for duplication events in all genomes, as well as evidence for recent tandem duplication events in the zebrafish, indicating that the complexity of the connexin family is growing. The identification of a third complete connexin gene family provides novel insight into the evolution of connexins, and sheds light into the phenotypic evolution of intercellular communication via gap junctions.
Collapse
Affiliation(s)
- Stephen D Eastman
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Iacocca B-217, Bethlehem, PA 18015, USA
| | | | | | | | | |
Collapse
|
13
|
De Boer TP, Kok B, Neuteboom KIE, Spieker N, De Graaf J, Destrée OHJ, Rook MB, Van Veen TAB, Jongsma HJ, Vos MA, De Bakker JMT, Van Der Heyden MAG. Cloning and functional characterization of a novel connexin expressed in somites of Xenopus laevis. Dev Dyn 2005; 233:864-71. [PMID: 15895416 DOI: 10.1002/dvdy.20420] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Connexin-containing gap junctions play an essential role in vertebrate development. More than 20 connexin isoforms have been identified in mammals. However, the number identified in Xenopus trails with only six isoforms described. Here, identification of a new connexin isoform from Xenopus laevis is described. Connexin40.4 was found by screening expressed sequence tag databases and carrying out polymerase chain reaction on genomic DNA. This new connexin has limited amino acid identity with mammalian (<50%) connexins, but conservation is higher (approximately 62%) with fish. During Xenopus laevis development, connexin40.4 was first expressed after the mid-blastula transition. There was prominent expression in the presomitic paraxial mesoderm and later in the developing somites. In adult frogs, expression was detected in kidney and stomach as well as in brain, heart, and skeletal muscle. Ectopic expression of connexin40.4 in HEK293 cells, resulted in formation of gap junction like structures at the cell interfaces. Similar ectopic expression in neural N2A cells resulted in functional electrical coupling, displaying mild, asymmetric voltage dependence. We thus cloned a novel connexin from Xenopus laevis, strongly expressed in developing somites, with no apparent orthologue in mammals.
Collapse
Affiliation(s)
- Teun P De Boer
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|