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Jimenez Gonzalez A, Baranasic D, Müller F. Zebrafish regulatory genomic resources for disease modelling and regeneration. Dis Model Mech 2023; 16:dmm050280. [PMID: 37529920 PMCID: PMC10417509 DOI: 10.1242/dmm.050280] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023] Open
Abstract
In the past decades, the zebrafish has become a disease model with increasing popularity owing to its advantages that include fast development, easy genetic manipulation, simplicity for imaging, and sharing conserved disease-associated genes and pathways with those of human. In parallel, studies of disease mechanisms are increasingly focusing on non-coding mutations, which require genome annotation maps of regulatory elements, such as enhancers and promoters. In line with this, genomic resources for zebrafish research are expanding, producing a variety of genomic data that help in defining regulatory elements and their conservation between zebrafish and humans. Here, we discuss recent developments in generating functional annotation maps for regulatory elements of the zebrafish genome and how this can be applied to human diseases. We highlight community-driven developments, such as DANIO-CODE, in generating a centralised and standardised catalogue of zebrafish genomics data and functional annotations; consider the advantages and limitations of current annotation maps; and offer considerations for interpreting and integrating existing maps with comparative genomics tools. We also discuss the need for developing standardised genomics protocols and bioinformatic pipelines and provide suggestions for the development of analysis and visualisation tools that will integrate various multiomic bulk sequencing data together with fast-expanding data on single-cell methods, such as single-cell assay for transposase-accessible chromatin with sequencing. Such integration tools are essential to exploit the multiomic chromatin characterisation offered by bulk genomics together with the cell-type resolution offered by emerging single-cell methods. Together, these advances will build an expansive toolkit for interrogating the mechanisms of human disease in zebrafish.
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Affiliation(s)
- Ada Jimenez Gonzalez
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Damir Baranasic
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, London SW7 2AZ, UK
- MRC London Institute of Medical Sciences, London W12 0NN, UK
- Division of Electronics, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Ferenc Müller
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
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2
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First Genome of Rock Lizard Darevskia valentini Involved in Formation of Several Parthenogenetic Species. Genes (Basel) 2022; 13:genes13091569. [PMID: 36140737 PMCID: PMC9498476 DOI: 10.3390/genes13091569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 08/22/2022] [Accepted: 08/27/2022] [Indexed: 11/22/2022] Open
Abstract
The extant reptiles are one of the most diverse clades among terrestrial vertebrates and one of a few groups with instances of parthenogenesis. Due to the hybrid origin of parthenogenetic species, reference genomes of the parental species as well as of the parthenogenetic progeny are indispensable to explore the genetic foundations of parthenogenetic reproduction. Here, we report on the first genome assembly of rock lizard Darevskia valentini, a paternal species for several parthenogenetic lineages. The novel genome was used in the reconstruction of the comprehensive phylogeny of Squamata inferred independently from 7369 trees of single-copy orthologs and a supermatrix of 378 conserved proteins. We also investigated Hox clusters, the loci that are often regarded as playing an important role in the speciation of animal groups with drastically diverse morphology. We demonstrated that Hox clusters of D. valentini are invaded with transposons and contain the HoxC1 gene that has been considered to be lost in the amniote ancestor. This study provides confirmation for previous works and releases new genomic data that will contribute to future discoveries on the mechanisms of parthenogenesis as well as support comparative studies among reptiles.
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3
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MacKenzie A, Hay EA, McEwan AR. Context-dependant enhancers as a reservoir of functional polymorphisms and epigenetic markers linked to alcohol use disorders and comorbidities. ADDICTION NEUROSCIENCE 2022; 2:None. [PMID: 35712020 PMCID: PMC9101288 DOI: 10.1016/j.addicn.2022.100014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/18/2022] [Accepted: 03/22/2022] [Indexed: 10/25/2022]
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4
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Panara V, Monteiro R, Koltowska K. Epigenetic Regulation of Endothelial Cell Lineages During Zebrafish Development-New Insights From Technical Advances. Front Cell Dev Biol 2022; 10:891538. [PMID: 35615697 PMCID: PMC9125237 DOI: 10.3389/fcell.2022.891538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 04/10/2022] [Indexed: 01/09/2023] Open
Abstract
Epigenetic regulation is integral in orchestrating the spatiotemporal regulation of gene expression which underlies tissue development. The emergence of new tools to assess genome-wide epigenetic modifications has enabled significant advances in the field of vascular biology in zebrafish. Zebrafish represents a powerful model to investigate the activity of cis-regulatory elements in vivo by combining technologies such as ATAC-seq, ChIP-seq and CUT&Tag with the generation of transgenic lines and live imaging to validate the activity of these regulatory elements. Recently, this approach led to the identification and characterization of key enhancers of important vascular genes, such as gata2a, notch1b and dll4. In this review we will discuss how the latest technologies in epigenetics are being used in the zebrafish to determine chromatin states and assess the function of the cis-regulatory sequences that shape the zebrafish vascular network.
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Affiliation(s)
- Virginia Panara
- Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Rui Monteiro
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom,Birmingham Centre of Genome Biology, University of Birmingham, Birmingham, United Kingdom
| | - Katarzyna Koltowska
- Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden,*Correspondence: Katarzyna Koltowska,
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5
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Chua EHZ, Yasar S, Harmston N. The importance of considering regulatory domains in genome-wide analyses - the nearest gene is often wrong! Biol Open 2022; 11:274931. [PMID: 35377406 PMCID: PMC9002814 DOI: 10.1242/bio.059091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The expression of a large number of genes is regulated by regulatory elements that are located far away from their promoters. Identifying which gene is the target of a specific regulatory element or is affected by a non-coding mutation is often accomplished by assigning these regions to the nearest gene in the genome. However, this heuristic ignores key features of genome organisation and gene regulation; in that the genome is partitioned into regulatory domains, which at some loci directly coincide with the span of topologically associated domains (TADs), and that genes are regulated by enhancers located throughout these regions, even across intervening genes. In this review, we examine the results from genome-wide studies using chromosome conformation capture technologies and from those dissecting individual gene regulatory domains, to highlight that the phenomenon of enhancer skipping is pervasive and affects multiple types of genes. We discuss how simply assigning a genomic region of interest to its nearest gene is problematic and often leads to incorrect predictions and highlight that where possible information on both the conservation and topological organisation of the genome should be used to generate better hypotheses. The article has an associated Future Leader to Watch interview. Summary: Identifying which gene is the target of an enhancer is often accomplished by assigning it to the nearest gene, here we discuss how this heuristic can lead to incorrect predictions.
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Affiliation(s)
| | - Samen Yasar
- Science Division, Yale-NUS College, Singapore 138527, Singapore
| | - Nathan Harmston
- Science Division, Yale-NUS College, Singapore 138527, Singapore.,Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore 169857, Singapore
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6
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7
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Review: Assessing fish welfare in research and aquaculture, with a focus on European directives. Animal 2018; 13:161-170. [PMID: 29717679 DOI: 10.1017/s1751731118000940] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The number of farmed fish in the world has increased considerably. Aquaculture is a growing industry that will in the future provide a large portion of fishery products. Moreover, in recent years, the number of teleost fish used as animal models for scientific research in both biomedical and ecological fields has increased. Therefore, it is increasingly important to implement measures designed to enhance the welfare of these animals. Currently, a number of European rules exist as requirements for the establishment, care and accommodation of fish maintained for human purposes. As far as (teleost) fish are concerned, the fact that the number of extant species is much greater than that of all other vertebrates must be considered. Of further importance is that each species has its own specific physical and chemical requirements. These factors make it difficult to provide generalized recommendations or requirements for all fish species. An adequate knowledge is required of the physiology and ecology of each species bred. This paper integrates and discusses, in a single synthesis, the current issues related to fish welfare, considering that teleosts are target species for both aquaculture and experimental models in biological and biomedical research. We first focus on the practical aspects, which must be considered when assessing fish welfare in both research and aquaculture contexts. Next, we address husbandry and the care of fish housed in research laboratories and aquaculture facilities in relation to their physiological and behavioural requirements, as well as in reference to the suggestions provided by European regulations. Finally, to evaluate precisely which parameters described by Directive 2010/63/EU are reported in scientific papers, we analysed 82 articles published by European researchers in 2014 and 2015. This review found that there is a general lack of information related to the optimal environmental conditions that should be provided for the range of species covered by this directive.
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8
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Polychronopoulos D, King JWD, Nash AJ, Tan G, Lenhard B. Conserved non-coding elements: developmental gene regulation meets genome organization. Nucleic Acids Res 2018; 45:12611-12624. [PMID: 29121339 PMCID: PMC5728398 DOI: 10.1093/nar/gkx1074] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/24/2017] [Indexed: 12/20/2022] Open
Abstract
Comparative genomics has revealed a class of non-protein-coding genomic sequences that display an extraordinary degree of conservation between two or more organisms, regularly exceeding that found within protein-coding exons. These elements, collectively referred to as conserved non-coding elements (CNEs), are non-randomly distributed across chromosomes and tend to cluster in the vicinity of genes with regulatory roles in multicellular development and differentiation. CNEs are organized into functional ensembles called genomic regulatory blocks–dense clusters of elements that collectively coordinate the expression of shared target genes, and whose span in many cases coincides with topologically associated domains. CNEs display sequence properties that set them apart from other sequences under constraint, and have recently been proposed as useful markers for the reconstruction of the evolutionary history of organisms. Disruption of several of these elements is known to contribute to diseases linked with development, and cancer. The emergence, evolutionary dynamics and functions of CNEs still remain poorly understood, and new approaches are required to enable comprehensive CNE identification and characterization. Here, we review current knowledge and identify challenges that need to be tackled to resolve the impasse in understanding extreme non-coding conservation.
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Affiliation(s)
- Dimitris Polychronopoulos
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - James W D King
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - Alexander J Nash
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - Ge Tan
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK
| | - Boris Lenhard
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.,Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, N-5008 Bergen, Norway
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9
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Hahn ME, Timme-Laragy AR, Karchner SI, Stegeman JJ. Nrf2 and Nrf2-related proteins in development and developmental toxicity: Insights from studies in zebrafish (Danio rerio). Free Radic Biol Med 2015; 88:275-289. [PMID: 26130508 PMCID: PMC4698826 DOI: 10.1016/j.freeradbiomed.2015.06.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 06/11/2015] [Accepted: 06/15/2015] [Indexed: 12/14/2022]
Abstract
Oxidative stress is an important mechanism of chemical toxicity, contributing to developmental toxicity and teratogenesis as well as to cardiovascular and neurodegenerative diseases and diabetic embryopathy. Developing animals are especially sensitive to effects of chemicals that disrupt the balance of processes generating reactive species and oxidative stress, and those anti-oxidant defenses that protect against oxidative stress. The expression and inducibility of anti-oxidant defenses through activation of NFE2-related factor 2 (Nrf2) and related proteins is an essential process affecting the susceptibility to oxidants, but the complex interactions of Nrf2 in determining embryonic response to oxidants and oxidative stress are only beginning to be understood. The zebrafish (Danio rerio) is an established model in developmental biology and now also in developmental toxicology and redox signaling. Here we review the regulation of genes involved in protection against oxidative stress in developing vertebrates, with a focus on Nrf2 and related cap'n'collar (CNC)-basic-leucine zipper (bZIP) transcription factors. Vertebrate animals including zebrafish share Nfe2, Nrf1, Nrf2, and Nrf3 as well as a core set of genes that respond to oxidative stress, contributing to the value of zebrafish as a model system with which to investigate the mechanisms involved in regulation of redox signaling and the response to oxidative stress during embryolarval development. Moreover, studies in zebrafish have revealed nrf and keap1 gene duplications that provide an opportunity to dissect multiple functions of vertebrate NRF genes, including multiple sensing mechanisms involved in chemical-specific effects.
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Affiliation(s)
- Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
| | - Alicia R Timme-Laragy
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America; Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Sibel I Karchner
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - John J Stegeman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
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10
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Rinkwitz S, Geng FS, Manning E, Suster M, Kawakami K, Becker TS. BAC transgenic zebrafish reveal hypothalamic enhancer activity around obesity associated SNP rs9939609 within the human FTO gene. Genesis 2015; 53:640-51. [PMID: 26271004 PMCID: PMC5054831 DOI: 10.1002/dvg.22884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/05/2015] [Accepted: 08/12/2015] [Indexed: 12/22/2022]
Abstract
Single Nucleotide Polymorphisms in FTO intron 1 have been associated with obesity risk, leading to the hypothesis that FTO is the obesity‐related gene. However, other studies have shown that the FTO gene is part of the regulatory domain of the neighboring IRX3 gene and that enhancers in FTO intron 1 regulate IRX3. While Irx3 activity was shown to be necessary in the hypothalamus for the metabolic function of Irx3 in mouse, no enhancers with hypothalamic activity have been demonstrated in the risk‐associated region within FTO. In order to identify potential enhancers at the human FTO locus in vivo, we tested regulatory activity in FTO intron 1 using BAC transgenesis in zebrafish. A minimal gata2 promoter‐GFP cassette was inserted 1.3 kb upstream of the obesity associated SNP rs9939609 in a human FTO BAC plasmid. In addition to the previously identified expression domains in notochord and kidney, human FTO BAC:GFP transgenic zebrafish larvae expressed GFP in the ventral posterior tuberculum, the posterior hypothalamus and the anterior brainstem, which are also expression domains of zebrafish irx3a. In contrast, an in‐frame insertion of a GFP cassette at the FTO start codon resulted in weak ubiquitous GFP expression indicating that the promoter of FTO does likely not react to enhancers located in the obesity risk‐associated region. genesis 53:640–651, 2015. © 2015 The Authors. genesis Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Silke Rinkwitz
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.,Department of Physiology, School of Medicine, University of Sydney, Australia
| | - Fan-Suo Geng
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia
| | - Elizabeth Manning
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia
| | | | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Thomas S Becker
- Brain and Mind Research Institute, School of Medicine, University of Sydney, Camperdown, New South Wales, Australia.,Department of Physiology, School of Medicine, University of Sydney, Australia
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11
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Copy number variants in patients with intellectual disability affect the regulation of ARX transcription factor gene. Hum Genet 2015; 134:1163-82. [PMID: 26337422 DOI: 10.1007/s00439-015-1594-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 08/16/2015] [Indexed: 10/23/2022]
Abstract
Protein-coding mutations in the transcription factor-encoding gene ARX cause various forms of intellectual disability (ID) and epilepsy. In contrast, variations in surrounding non-coding sequences are correlated with milder forms of non-syndromic ID and autism and had suggested the importance of ARX gene regulation in the etiology of these disorders. We compile data on several novel and some already identified patients with or without ID that carry duplications of ARX genomic region and consider likely genetic mechanisms underlying the neurodevelopmental defects. We establish the long-range regulatory domain of ARX and identify its brain region-specific autoregulation. We conclude that neurodevelopmental disturbances in the patients may not simply arise from increased dosage due to ARX duplication. This is further exemplified by a small duplication involving a non-functional ARX copy, but with duplicated enhancers. ARX enhancers are located within a 504-kb region and regulate expression specifically in the forebrain in developing and adult zebrafish. Transgenic enhancer-reporter lines were used as in vivo tools to delineate a brain region-specific negative and positive autoregulation of ARX. We find autorepression of ARX in the telencephalon and autoactivation in the ventral thalamus. Fluorescently labeled brain regions in the transgenic lines facilitated the identification of neuronal outgrowth and pathfinding disturbances in the ventral thalamus and telencephalon that occur when arxa dosage is diminished. In summary, we have established a model for how breakpoints in long-range gene regulation alter the expression levels of a target gene brain region-specifically, and how this can cause subtle neuronal phenotypes relating to the etiology of associated neuropsychiatric disease.
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12
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Immediate and long-term consequences of vascular toxicity during zebrafish development. Reprod Toxicol 2014; 48:51-61. [PMID: 24907688 DOI: 10.1016/j.reprotox.2014.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/21/2014] [Accepted: 05/27/2014] [Indexed: 01/02/2023]
Abstract
Proper formation of the vascular system is necessary for embryogenesis, and chemical disruption of vascular development may be a key event driving developmental toxicity. In order to test the effect of environmental chemicals on this critical process, we evaluated a quantitative assay in transgenic zebrafish using angiogenesis inhibitors that target VEGFR2 (PTK787) or EGFR (AG1478). Both PTK787 and AG1478 exposure impaired intersegmental vessel (ISV) sprouting, while AG1478 also produced caudal and pectoral fin defects at concentrations below those necessary to blunt ISV morphogenesis. The functional consequences of vessel toxicity during early development included decreased body length and survival in juvenile cohorts developmentally exposed to inhibitor concentrations sufficient to completely block ISV sprouting angiogenesis. These data show that concentration-dependent disruption of the presumed targets for these inhibitors produce adverse outcomes at advanced life stages.
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13
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Sharma Y, Chilamakuri CSR, Bakke M, Lenhard B. Computational characterization of modes of transcriptional regulation of nuclear receptor genes. PLoS One 2014; 9:e88880. [PMID: 24551185 PMCID: PMC3923872 DOI: 10.1371/journal.pone.0088880] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/15/2014] [Indexed: 11/18/2022] Open
Abstract
Background Nuclear receptors are a large structural class of transcription factors that act with their co-regulators and repressors to maintain a variety of biological and physiological processes such as metabolism, development and reproduction. They are activated through the binding of small ligands, which can be replaced by drug molecules, making nuclear receptors promising drug targets. Transcriptional regulation of the genes that encode them is central to gaining a deeper understanding of the diversity of their biochemical and biophysical roles and their role in disease and therapy. Even though they share evolutionary history, nuclear receptor genes have fundamentally different expression patterns, ranging from ubiquitously expressed to tissue-specific and spatiotemporally complex. However, current understanding of regulation in nuclear receptor gene family is still nascent. Methodology/Principal Findings In this study, we investigate the relationship between long-range regulation of nuclear receptor family and their known functionality. Towards this goal, we identify the nuclear receptor genes that are potential targets based on counts of highly conserved non-coding elements. We validate our results using publicly available expression (RNA-seq) and histone modification (ChIP-seq) data from the ENCODE project. We find that nuclear receptor genes involved in developmental roles show strong evidence of long-range mechanism of transcription regulation with distinct cis-regulatory content they feature clusters of highly conserved non-coding elements distributed in regions spanning several Megabases, long and multiple CpG islands, bivalent promoter marks and statistically significant higher enrichment of enhancer mark around their gene loci. On the other hand nuclear receptor genes that are involved in tissue-specific roles lack these features, having simple transcriptional controls and a greater variety of mechanisms for producing paralogs. We further examine the combinatorial patterns of histone maps associated with dynamic functional elements in order to explore the regulatory landscape of the gene family. The results show that our proposed classification capturing long-range regulation is strongly indicative of the functional roles of the nuclear receptors compared to existing classifications. Conclusions/Significanc We present a new classification for nuclear receptor gene family capturing whether a nuclear receptor is a possible target of long-range regulation or not. We compare our classification to existing structural (mechanism of action) and homology-based classifications. Our results show that understanding long-range regulation of nuclear receptors can provide key insight into their functional roles as well as evolutionary history; and this strongly merits further study.
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Affiliation(s)
- Yogita Sharma
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Boris Lenhard
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, and MRC Clinical Sciences Centre, London, United Kingdom
- Department of Informatics, University of Bergen, Bergen, Norway
- * E-mail:
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Matsunami M, Saitou N. Vertebrate paralogous conserved noncoding sequences may be related to gene expressions in brain. Genome Biol Evol 2013; 5:140-50. [PMID: 23267051 PMCID: PMC3595034 DOI: 10.1093/gbe/evs128] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Vertebrate genomes include gene regulatory elements in protein-noncoding regions. A part of gene regulatory elements are expected to be conserved according to their functional importance, so that evolutionarily conserved noncoding sequences (CNSs) might be good candidates for those elements. In addition, paralogous CNSs, which are highly conserved among both orthologous loci and paralogous loci, have the possibility of controlling overlapping expression patterns of their adjacent paralogous protein-coding genes. The two-round whole-genome duplications (2R WGDs), which most probably occurred in the vertebrate common ancestors, generated large numbers of paralogous protein-coding genes and their regulatory elements. These events could contribute to the emergence of vertebrate features. However, the evolutionary history and influences of the 2R WGDs are still unclear, especially in noncoding regions. To address this issue, we identified paralogous CNSs. Region-focused Basic Local Alignment Search Tool (BLAST) search of each synteny block revealed 7,924 orthologous CNSs and 309 paralogous CNSs conserved among eight high-quality vertebrate genomes. Paralogous CNSs we found contained 115 previously reported ones and newly detected 194 ones. Through comparisons with VISTA Enhancer Browser and available ChIP-seq data, one-third (103) of paralogous CNSs detected in this study showed gene regulatory activity in the brain at several developmental stages. Their genomic locations are highly enriched near the transcription factor-coding regions, which are expressed in brain and neural systems. These results suggest that paralogous CNSs are conserved mainly because of maintaining gene expression in the vertebrate brain.
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Affiliation(s)
- Masatoshi Matsunami
- Department of Genetics, School of Life Science, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
- Division of Population Genetics, National Institute of Genetics, Mishima, Japan
- Present address: Laboratory of Ecology and Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan
| | - Naruya Saitou
- Department of Genetics, School of Life Science, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
- Division of Population Genetics, National Institute of Genetics, Mishima, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
- *Corresponding author: E-mail:
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15
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Harmston N, Lenhard B. Chromatin and epigenetic features of long-range gene regulation. Nucleic Acids Res 2013; 41:7185-99. [PMID: 23766291 PMCID: PMC3753629 DOI: 10.1093/nar/gkt499] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The precise regulation of gene transcription during metazoan development is controlled by a complex system of interactions between transcription factors, histone modifications and modifying enzymes and chromatin conformation. Developments in chromosome conformation capture technologies have revealed that interactions between regions of chromatin are pervasive and highly cell-type specific. The movement of enhancers and promoters in and out of higher-order chromatin structures within the nucleus are associated with changes in expression and histone modifications. However, the factors responsible for mediating these changes and determining enhancer:promoter specificity are still not completely known. In this review, we summarize what is known about the patterns of epigenetic and chromatin features characteristic of elements involved in long-range interactions. In addition, we review the insights into both local and global patterns of chromatin interactions that have been revealed by the latest experimental and computational methods.
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Affiliation(s)
- Nathan Harmston
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London W12 0NN, UK, Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London W12 0NN, UK and Department of Informatics, University of Bergen, Thromøhlensgate 55, N-5008 Bergen, Norway
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16
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Becker TS, Rinkwitz S. Zebrafish as a genomics model for human neurological and polygenic disorders. Dev Neurobiol 2012; 72:415-28. [PMID: 21465670 DOI: 10.1002/dneu.20888] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Whole exome sequencing and, to a lesser extent, genome-wide association studies, have provided unprecedented advances in identifying genes and candidate genomic regions involved in the development of human disease. Further progress will come from sequencing the entire genome of multiple patients and normal controls to evaluate overall mutational burden and disease risk. A major challenge will be the interpretation of the resulting data and distinguishing true pathogenic mutations from rare benign variants.While in model organisms such as the zebrafish,mutants are sought that disrupt the function of individual genes, human mutations that cause, or are associated with, the development of disease, are often not acting in a Mendelian fashion, are frequently of small effect size, are late onset, and may reside in noncoding parts of the genome. The zebrafish model is uniquely poised for understanding human coding- and noncoding variants because of its sequenced genome, a large body of knowledge on gene expression and function, rapid generation time, and easy access to embryos. A critical advantage is the ease of zebrafish transgenesis, both for the testing of human regulatory DNA driving expression of fluorescent reporter proteins, and the expression of mutated disease-associated human proteins in specific neurons to rapidly model aspects of neurological disorders. The zebrafish affords progress both through its model genome and it is rapidly developing transparent model vertebrate embryo.
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Affiliation(s)
- Thomas S Becker
- Sydney Medical School, University of Sydney, Camperdown, Australia.
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17
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Chatterjee S, Lufkin T. Regulatory genomics: Insights from the zebrafish. CURRENT TOPICS IN GENETICS 2012; 5:1-10. [PMID: 23440612 PMCID: PMC3577074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The sequencing of many vertebrate species over the last decade has opened up the possibility of using comparative genomics as a powerful tool to elucidate regulatory elements in the vertebrate genome. The zebrafish has played a pivotal role in this process. Its genome has been used in large-scale genome comparisons to locate vertebrate specific regulatory elements and also it has been an excellent model system to test out the predicted DNA sequences for their ability to drive reporter gene expression in vivo. In spite of all the successes there have still been some issues in using the zebrafish as a model system for these kinds of assays. This review will shed some light on the successes and failures of the zebrafish in pushing forward regulatory genomics.
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Affiliation(s)
- Sumantra Chatterjee
- Stem Cell and Developmental Biology, Genome Institute of Singapore, 60 Biopolis Street, 138672, Singapore
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18
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Fujimoto E, Stevenson TJ, Chien CB, Bonkowsky JL. Identification of a dopaminergic enhancer indicates complexity in vertebrate dopamine neuron phenotype specification. Dev Biol 2011; 352:393-404. [PMID: 21276790 PMCID: PMC3069253 DOI: 10.1016/j.ydbio.2011.01.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 01/13/2011] [Accepted: 01/19/2011] [Indexed: 01/05/2023]
Abstract
The dopaminergic neurons of the basal ganglia play critical roles in CNS function and human disease, but specification of dopamine neuron phenotype is poorly understood in vertebrates. We performed an in vivo screen in zebrafish to identify dopaminergic neuron enhancers, in order to facilitate studies on the specification of neuronal identity, connectivity, and function in the basal ganglia. Based primarily on identification of conserved non-coding elements, we tested 54 DNA elements from four species (zebrafish, pufferfish, mouse, and rat), that included 21 genes with known or putative roles in dopaminergic neuron specification or function. Most elements failed to drive CNS expression or did not express specifically in dopaminergic neurons. However, we did isolate a discrete enhancer from the otpb gene that drove specific expression in diencephalic dopaminergic neurons, although it did not share sequence conservation with regulatory regions of otpa or other dopamine-specific genes. For the otpb enhancer, regulation of expression in dopamine neurons requires multiple elements spread across a large genomic area. In addition, we compared our in vivo testing with in silico analysis of genomic regions for genes involved in dopamine neuron function, but failed to find conserved regions that functioned as enhancers. We conclude that regulation of dopaminergic neuron phenotype in vertebrates is regulated by dispersed regulatory elements.
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Affiliation(s)
- Esther Fujimoto
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah 84132
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Tamara J. Stevenson
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Chi-Bin Chien
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132
| | - Joshua L. Bonkowsky
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah 84132
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132
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19
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Rieger S, Wang F, Sagasti A. Time-lapse imaging of neural development: zebrafish lead the way into the fourth dimension. Genesis 2011; 49:534-45. [PMID: 21305690 DOI: 10.1002/dvg.20729] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 01/01/2023]
Abstract
Time-lapse imaging is often the only way to appreciate fully the many dynamic cell movements critical to neural development. Zebrafish possess many advantages that make them the best vertebrate model organism for live imaging of dynamic development events. This review will discuss technical considerations of time-lapse imaging experiments in zebrafish, describe selected examples of imaging studies in zebrafish that revealed new features or principles of neural development, and consider the promise and challenges of future time-lapse studies of neural development in zebrafish embryos and adults.
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Affiliation(s)
- Sandra Rieger
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, California, USA
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20
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Korzh V, Teh C, Kondrychyn I, Chudakov DM, Lukyanov S. Visualizing Compound Transgenic Zebrafish in Development: A Tale of Green Fluorescent Protein and KillerRed. Zebrafish 2011; 8:23-9. [DOI: 10.1089/zeb.2011.0689] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Vladimir Korzh
- Genomics and Development Division, Institute of Molecular and Cell Biology, A-STAR, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Cathleen Teh
- Genomics and Development Division, Institute of Molecular and Cell Biology, A-STAR, Singapore, Singapore
| | - Igor Kondrychyn
- Genomics and Development Division, Institute of Molecular and Cell Biology, A-STAR, Singapore, Singapore
| | - Dmitry M. Chudakov
- Shemiakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russia
| | - Sergey Lukyanov
- Shemiakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russia
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Renninger SL, Schonthaler HB, Neuhauss SCF, Dahm R. Investigating the genetics of visual processing, function and behaviour in zebrafish. Neurogenetics 2011; 12:97-116. [PMID: 21267617 DOI: 10.1007/s10048-011-0273-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 01/04/2011] [Indexed: 12/11/2022]
Abstract
Over the past three decades, the zebrafish has been proven to be an excellent model to investigate the genetic control of vertebrate embryonic development, and it is now also increasingly used to study behaviour and adult physiology. Moreover, mutagenesis approaches have resulted in large collections of mutants with phenotypes that resemble human pathologies, suggesting that these lines can be used to model diseases and screen drug candidates. With the recent development of new methods for gene targeting and manipulating or monitoring gene expression, the range of genetic modifications now possible in zebrafish is increasing rapidly. Combined with the classical strengths of the zebrafish as a model organism, these advances are set to substantially expand the type of biological questions that can be addressed in this species. In this review, we outline how the potential of the zebrafish can be harvested in the context of eye development and visual function. We review recent technological advances used to study the formation of the eyes and visual areas of the brain, visual processing on the cellular, subcellular and molecular level, and the genetics of visual behaviour in vertebrates.
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Affiliation(s)
- Sabine L Renninger
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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Abstract
Zebrafish offers significant opportunities for the investigation of vertebrate development, evolution, physiology, and behavior and provides numerous models of human disease. Connecting zebrafish phenogenetic biology to that of humans and other vertebrates, however, requires the proper assignment of gene orthologies. Orthology assignments by phylogenetic analysis or by reciprocal best sequence similarity searches can lead to errors, especially in cases of gene duplication followed by gene loss or rapid lineage-specific gene evolution. Conserved synteny analysis provides a method that helps overcome such problems. Here we describe conserved synteny analysis for zebrafish genes and discuss the Synteny Database, a website specifically designed to identify conserved syntenies for zebrafish that takes into account the teleost genome duplication (TGD). We utilize the Synteny Database to demonstrate its power to resolve our understanding of the evolution of nerve growth factor receptor related genes, including Ngfr and the enigmatic Nradd. Finally, we compare conserved syntenies between zebrafish, stickleback, spotted gar, and human to understand the timing of chromosome rearrangements in teleost genome evolution. An improved understanding of gene histories that comes from the application of tools provided by the Synteny Database can facilitate the connectivity of zebrafish and human genomes.
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Affiliation(s)
- Julian M Catchen
- University of Oregon, Center for Ecology and Evolutionary Biology, Eugene Oregon, USA
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23
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When needles look like hay: how to find tissue-specific enhancers in model organism genomes. Dev Biol 2010; 350:239-54. [PMID: 21130761 DOI: 10.1016/j.ydbio.2010.11.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 11/11/2010] [Accepted: 11/22/2010] [Indexed: 01/22/2023]
Abstract
A major prerequisite for the investigation of tissue-specific processes is the identification of cis-regulatory elements. No generally applicable technique is available to distinguish them from any other type of genomic non-coding sequence. Therefore, researchers often have to identify these elements by elaborate in vivo screens, testing individual regions until the right one is found. Here, based on many examples from the literature, we summarize how functional enhancers have been isolated from other elements in the genome and how they have been characterized in transgenic animals. Covering computational and experimental studies, we provide an overview of the global properties of cis-regulatory elements, like their specific interactions with promoters and target gene distances. We describe conserved non-coding elements (CNEs) and their internal structure, nucleotide composition, binding site clustering and overlap, with a special focus on developmental enhancers. Conflicting data and unresolved questions on the nature of these elements are highlighted. Our comprehensive overview of the experimental shortcuts that have been found in the different model organism communities and the new field of high-throughput assays should help during the preparation phase of a screen for enhancers. The review is accompanied by a list of general guidelines for such a project.
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Rinkwitz S, Mourrain P, Becker TS. Zebrafish: an integrative system for neurogenomics and neurosciences. Prog Neurobiol 2010; 93:231-43. [PMID: 21130139 DOI: 10.1016/j.pneurobio.2010.11.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 11/08/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
Abstract
Rapid technological advances over the past decade have moved us closer to a high throughput molecular approach to neurobiology, where we see the merging of neurogenetics, genomics, physiology, imaging and pharmacology. This is the case more in zebrafish than in any other model organism commonly used. Recent improvements in the generation of transgenic zebrafish now allow genetic manipulation and live imaging of neuronal development and function in early embryonic, larval, and adult animals. The sequenced zebrafish genome and comparative genomics give unprecedented insights into genome evolution and its relation to genome structure and function. There is now information on embryonic and larval expression of over 12,000 genes and just under 1000 mutant phenotypes. We review the remarkable similarity of the zebrafish genetic blueprint for the nervous system to that of mammals and assess recent technological advances that make the zebrafish a model of choice for elucidating the development and function of neuronal circuitry, transgene-based neuroanatomy, and small molecule neuropharmacology.
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Affiliation(s)
- Silke Rinkwitz
- Brain and Mind Research Institute, Sydney Medical School, University of Sydney, 100 Mallett St., Camperdown, NSW 2050, Australia
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25
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Chen X, Li X, Wang P, Liu Y, Zhang Z, Zhao G, Xu H, Zhu J, Qin X, Chen S, Hu L, Kong X. Novel association strategy with copy number variation for identifying new risk Loci of human diseases. PLoS One 2010; 5:e12185. [PMID: 20808825 PMCID: PMC2924882 DOI: 10.1371/journal.pone.0012185] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 07/20/2010] [Indexed: 12/20/2022] Open
Abstract
Background Copy number variations (CNV) are important causal genetic variations for human disease; however, the lack of a statistical model has impeded the systematic testing of CNVs associated with disease in large-scale cohort. Methodology/Principal Findings Here, we developed a novel integrated strategy to test CNV-association in genome-wide case-control studies. We converted the single-nucleotide polymorphism (SNP) signal to copy number states using a well-trained hidden Markov model. We mapped the susceptible CNV-loci through SNP site-specific testing to cope with the physiological complexity of CNVs. We also ensured the credibility of the associated CNVs through further window-based CNV-pattern clustering. Genome-wide data with seven diseases were used to test our strategy and, in total, we identified 36 new susceptible loci that are associated with CNVs for the seven diseases: 5 with bipolar disorder, 4 with coronary artery disease, 1 with Crohn's disease, 7 with hypertension, 9 with rheumatoid arthritis, 7 with type 1 diabetes and 3 with type 2 diabetes. Fifteen of these identified loci were validated through genotype-association and physiological function from previous studies, which provide further confidence for our results. Notably, the genes associated with bipolar disorder converged in the phosphoinositide/calcium signaling, a well-known affected pathway in bipolar disorder, which further supports that CNVs have impact on bipolar disorder. Conclusions/Significance Our results demonstrated the effectiveness and robustness of our CNV-association analysis and provided an alternative avenue for discovering new associated loci of human diseases.
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Affiliation(s)
- Xianfeng Chen
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
| | - Xinlei Li
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
| | - Ping Wang
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
| | - Yang Liu
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
| | - Zhenguo Zhang
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
| | - Guoping Zhao
- Chinese National Human Genome Center at Shanghai, Shanghai, People's Republic of China
| | - Haiming Xu
- Institute of Bioinformatics, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Jun Zhu
- Institute of Bioinformatics, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, People's Republic of China
| | - Xueying Qin
- State Key Laboratory of Computer Aided Design and Computer Graphics, Zhejiang University, Hangzhou, People's Republic of China
| | - Suchao Chen
- State Key Laboratory of Computer Aided Design and Computer Graphics, Zhejiang University, Hangzhou, People's Republic of China
| | - Landian Hu
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
- State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
| | - Xiangyin Kong
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) and Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, People's Republic of China
- State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
- * E-mail:
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26
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Kapasa M, Arhondakis S, Kossida S. Phylogenetic and regulatory region analysis of Wnt5 genes reveals conservation of a regulatory module with putative implication in pancreas development. Biol Direct 2010; 5:49. [PMID: 20684756 PMCID: PMC2922100 DOI: 10.1186/1745-6150-5-49] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Accepted: 08/04/2010] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Wnt5 genes belong to the large Wnt family, encoding proteins implicated into several tumorigenic and developmental processes. Phylogenetic analyses showed that Wnt5 gene has been duplicated at the divergence time of gnathostomata from agnatha. Interestingly, experimental data for some species indicated that only one of the two Wnt5 paralogs participates in the development of the endocrine pancreas. The purpose of this paper is to reexamine the phylogenetic history of the Wnt5 developmental regulators and investigate the functional shift between paralogs through comparative genomics. RESULTS In this study, the phylogeny of Wnt5 genes was investigated in species belonging to protostomia and deuterostomia. Furthermore, an in silico regulatory region analysis of Wnt5 paralogs was conducted, limited to those species with insulin producing cells and pancreas, covering the evolutionary distance from agnatha to gnathostomata. Our results confirmed the Wnt5 gene duplication and additionally revealed that this duplication event included also the upstream region. Moreover, within this latter region, a conserved module was detected to which a complex of transcription factors, known to be implicated in embryonic pancreas formation, bind. CONCLUSIONS Results and observations presented in this study, allow us to conclude that during evolution, the Wnt5 gene has been duplicated in early vertebrates, and that some paralogs conserved a module within their regulatory region, functionally related to embryonic development of pancreas. Interestingly, our results allowed advancing a possible explanation on why the Wnt5 orthologs do not share the same function during pancreas development. As a final remark, we suggest that an in silico comparative analysis of regulatory regions, especially when associated to published experimental data, represents a powerful approach for explaining shift of roles among paralogs.
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Affiliation(s)
- Maria Kapasa
- Bioinformatics & Medical Informatics Team, Biomedical Research Foundation of the Academy of Athens, 11527, Athens, Greece
- Developmental Biology Laboratory, Biomedical Research Foundation of the Academy of Athens, 11527, Athens, Greece
- Department of Pharmacy, School of Health Sciences, University of Patras, GR-26500 Rion-Patras, Greece
| | - Stilianos Arhondakis
- Bioinformatics & Medical Informatics Team, Biomedical Research Foundation of the Academy of Athens, 11527, Athens, Greece
| | - Sophia Kossida
- Bioinformatics & Medical Informatics Team, Biomedical Research Foundation of the Academy of Athens, 11527, Athens, Greece
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27
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Navratilova P, Fredman D, Lenhard B, Becker TS. Regulatory divergence of the duplicated chromosomal loci sox11a/b by subpartitioning and sequence evolution of enhancers in zebrafish. Mol Genet Genomics 2009; 283:171-84. [DOI: 10.1007/s00438-009-0503-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 12/01/2009] [Indexed: 01/05/2023]
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TIAN J, ZHAO ZH, CHEN HP. [Conserved non-coding elements in human genome]. YI CHUAN = HEREDITAS 2009; 31:1067-1076. [PMID: 19933086 DOI: 10.3724/sp.j.1005.2009.01067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Study of comparative genomics has revealed that about 5% of the human genome are under purifying selection, 3.5% of which are conserved non-coding elements (CNEs). While the coding regions comprise of only a small part. In human, the CNEs are functionally important, which may be associated with the process of the establishment and maintain of chromatin architecture, transcription regulation, and pre-mRNA processing. They are also related to ontogeny of mammals and human diseases. This review outlined the identification, functional significance, evolutionary origin, and effects on human genetic defects of the CNEs.
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Affiliation(s)
- Jing TIAN
- Institute of Biotechnology, Academy of Military Medical Science, Beijing 100071, China.
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29
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Komisarczuk AZ, Kawakami K, Becker TS. Cis-regulation and chromosomal rearrangement of the fgf8 locus after the teleost/tetrapod split. Dev Biol 2009; 336:301-12. [PMID: 19782672 DOI: 10.1016/j.ydbio.2009.09.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 09/02/2009] [Accepted: 09/18/2009] [Indexed: 12/23/2022]
Abstract
The complex expression pattern of fibroblast growth factor 8 (Fgf8) and the cellular responses dependent on concentration of its mRNA in vertebrates suggest that Fgf8 should be tightly controlled at the transcriptional level. We found zebrafish conserved noncoding elements (CNEs) with pan-vertebrate as well as fish-specific orthologous sequences from across 200 kb of the zebrafish fgf8a genomic regulatory block to direct reporter expression in patterns consistent with the expression pattern of fgf8a. These included elements from inside the introns of the skin-specific slc2a15a and the ubiquitously expressed fbxw4 bystander genes. The fgf8a/fbxw4 gene pair, which has remained joined throughout three whole genome duplications in chordate evolution, is inverted in teleost genomes, but CNEs across both evolutionary breakpoints showed specific activity. While some CNEs directed highly reproducible expression patterns, others were subject to variation but showed, in a subset of transgenes, expression in the apical ectodermal ridge, the anterior boundaries of somites and the midbrain-hindbrain boundary, specific Fgf8 signaling domains, suggesting that their activity may be context specific. A human element with tetrapod-specific orthologous sequences directed reporter expression to the vasculature, possibly corresponding to a tetrapod innovation. We conclude that fgf8a transcriptional regulation employs pan-vertebrate and teleost-specific enhancers dispersed over three genes in the zebrafish genome.
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Affiliation(s)
- Anna Z Komisarczuk
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, N-5008 Bergen, Norway
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30
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Fredman D, Engstrom PG, Lenhard B. Web-based tools and approaches to study long-range gene regulation in Metazoa. BRIEFINGS IN FUNCTIONAL GENOMICS AND PROTEOMICS 2009; 8:231-42. [DOI: 10.1093/bfgp/elp023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Abstract
Over recent years, several groundbreaking techniques have been developed that allow for the anatomical description of neurons, and the observation and manipulation of their activity. Combined, these approaches should provide a great leap forward in our understanding of the structure and connectivity of the nervous system and how, as a network of individual neurons, it generates behavior. Zebrafish, given their external development and optical transparency, are an appealing system in which to employ these methods. These traits allow for direct observation of fluorescence in describing anatomy and observing neural activity, and for the manipulation of neurons using a host of light-triggered proteins. Gal4/Upstream Activating Sequence techniques, as they are based on a binary system, allow for the flexible deployment of a range of transgenes in expression patterns of interest. As such, they provide a promising approach for viewing neurons in a variety of ways, each of which can reveal something different about their structure, connectivity, or function. In this study, the author will review recent progress in the development of the Gal4/Upstream Activating Sequence system in zebrafish, feature examples of promising studies to date, and examine how various new technologies can be used in the future to untangle the complex mechanisms by which behavior is generated.
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Affiliation(s)
- Ethan K Scott
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia.
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32
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Yang L, Ho NY, Alshut R, Legradi J, Weiss C, Reischl M, Mikut R, Liebel U, Müller F, Strähle U. Zebrafish embryos as models for embryotoxic and teratological effects of chemicals. Reprod Toxicol 2009; 28:245-53. [PMID: 19406227 DOI: 10.1016/j.reprotox.2009.04.013] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 04/07/2009] [Accepted: 04/20/2009] [Indexed: 01/04/2023]
Abstract
The experimental virtues of the zebrafish embryo such as small size, development outside of the mother, cheap maintenance of the adult made the zebrafish an excellent model for phenotypic genetic and more recently also chemical screens. The availability of a genome sequence and several thousand mutants and transgenic lines together with gene arrays and a broad spectrum of techniques to manipulate gene functions add further to the experimental strength of this model. Pioneering studies suggest that chemicals can have in many cases very similar toxicological and teratological effects in zebrafish embryos and humans. In certain areas such as cardiotoxicity, the zebrafish appears to outplay the traditional rodent models of toxicity testing. Several pilot projects used zebrafish embryos to identify new chemical entities with specific biological functions. In combination with the establishment of transgenic sensor lines and the further development of existing and new automated imaging systems, the zebrafish embryos could therefore be used as cost-effective and ethically acceptable animal models for drug screening as well as toxicity testing.
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Affiliation(s)
- Lixin Yang
- Institute of Toxicology and Genetics, Forschungszentrum Karlsruhe in the Helmholtz Association, Karlsruhe Institute of Technology, PO Box 3640, Karlsruhe 76021, Germany
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33
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Previti C, Harari O, Zwir I, del Val C. Profile analysis and prediction of tissue-specific CpG island methylation classes. BMC Bioinformatics 2009; 10:116. [PMID: 19383127 PMCID: PMC2683815 DOI: 10.1186/1471-2105-10-116] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 04/21/2009] [Indexed: 11/10/2022] Open
Abstract
Background The computational prediction of DNA methylation has become an important topic in the recent years due to its role in the epigenetic control of normal and cancer-related processes. While previous prediction approaches focused merely on differences between methylated and unmethylated DNA sequences, recent experimental results have shown the presence of much more complex patterns of methylation across tissues and time in the human genome. These patterns are only partially described by a binary model of DNA methylation. In this work we propose a novel approach, based on profile analysis of tissue-specific methylation that uncovers significant differences in the sequences of CpG islands (CGIs) that predispose them to a tissue- specific methylation pattern. Results We defined CGI methylation profiles that separate not only between constitutively methylated and unmethylated CGIs, but also identify CGIs showing a differential degree of methylation across tissues and cell-types or a lack of methylation exclusively in sperm. These profiles are clearly distinguished by a number of CGI attributes including their evolutionary conservation, their significance, as well as the evolutionary evidence of prior methylation. Additionally, we assess profile functionality with respect to the different compartments of protein coding genes and their possible use in the prediction of DNA methylation. Conclusion Our approach provides new insights into the biological features that determine if a CGI has a functional role in the epigenetic control of gene expression and the features associated with CGI methylation susceptibility. Moreover, we show that the ability to predict CGI methylation is based primarily on the quality of the biological information used and the relationships uncovered between different sources of knowledge. The strategy presented here is able to predict, besides the constitutively methylated and unmethylated classes, two more tissue specific methylation classes conserving the accuracy provided by leading binary methylation classification methods.
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Affiliation(s)
- Christopher Previti
- Department of Molecular Biophysics, DKFZ, German Cancer Research Center, Heidelberg, Germany.
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Akalin A, Fredman D, Arner E, Dong X, Bryne JC, Suzuki H, Daub CO, Hayashizaki Y, Lenhard B. Transcriptional features of genomic regulatory blocks. Genome Biol 2009; 10:R38. [PMID: 19374772 PMCID: PMC2688929 DOI: 10.1186/gb-2009-10-4-r38] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 02/10/2009] [Accepted: 04/19/2009] [Indexed: 12/23/2022] Open
Abstract
CAGE tag mapping of transcription start sites across different human tissues shows that genomic regulatory blocks have unique features that are the likely cause of their ability to respond to regulatory inputs from very long distances. Background Genomic regulatory blocks (GRBs) are chromosomal regions spanned by highly conserved non-coding elements (HCNEs), most of which serve as regulatory inputs of one target gene in the region. The target genes are most often transcription factors involved in embryonic development and differentiation. GRBs often contain extensive gene deserts, as well as additional 'bystander' genes intertwined with HCNEs but whose expression and function are unrelated to those of the target gene. The tight regulation of target genes, complex arrangement of regulatory inputs, and the differential responsiveness of genes in the region call for the examination of fundamental rules governing transcriptional activity in GRBs. Here we use extensive CAGE tag mapping of transcription start sites across different human tissues and differentiation stages combined with expression data and a number of sequence and epigenetic features to discover these rules and patterns. Results We show evidence that GRB target genes have properties that set them apart from their bystanders as well as other genes in the genome: longer CpG islands, a higher number and wider spacing of alternative transcription start sites, and a distinct composition of transcription factor binding sites in their core/proximal promoters. Target gene expression correlates with the acetylation state of HCNEs in the region. Additionally, target gene promoters have a distinct combination of activating and repressing histone modifications in mouse embryonic stem cell lines. Conclusions GRB targets are genes with a number of unique features that are the likely cause of their ability to respond to regulatory inputs from very long distances.
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Affiliation(s)
- Altuna Akalin
- Computational Biology Unit, Bergen Center for Computational Science, and Sars Centre for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
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Navratilova P, Fredman D, Hawkins TA, Turner K, Lenhard B, Becker TS. Systematic human/zebrafish comparative identification of cis-regulatory activity around vertebrate developmental transcription factor genes. Dev Biol 2008; 327:526-40. [PMID: 19073165 DOI: 10.1016/j.ydbio.2008.10.044] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/02/2008] [Accepted: 10/28/2008] [Indexed: 01/01/2023]
Abstract
Pan-vertebrate developmental cis-regulatory elements are discernible as highly conserved noncoding elements (HCNEs) and are often dispersed over large areas around the pleiotropic genes whose expression they control. On the loci of two developmental transcription factor genes, SOX3 and PAX6, we demonstrate that HCNEs conserved between human and zebrafish can be systematically and reliably tested for their regulatory function in multiple stable transgenes in zebrafish, and their genomic reach estimated with confidence using synteny conservation and HCNE density along these loci. HCNEs of both human and zebrafish function as specific developmental enhancers in zebrafish. We show that human HCNEs result in expression patterns in zebrafish equivalent to those in mouse, establishing zebrafish as a suitable model for large-scale testing of human developmental enhancers. Orthologous human and zebrafish enhancers underwent functional evolution within their sequence and often directed related but non-identical expression patterns. Despite an evolutionary distance of 450 million years, one pax6 HCNE drove expression in identical areas when comparing zebrafish vs. human HCNEs. HCNEs from the same area often drive overlapping patterns, suggesting that multiple regulatory inputs are required to achieve robust and precise complex expression patterns exhibited by developmental genes.
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Affiliation(s)
- Pavla Navratilova
- Sars Centre for Marine Molecular Biology, University of Bergen, 5008 Bergen, Norway
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Jao LE, Maddison L, Chen W, Burgess SM. Using retroviruses as a mutagenesis tool to explore the zebrafish genome. BRIEFINGS IN FUNCTIONAL GENOMICS AND PROTEOMICS 2008; 7:427-43. [PMID: 18977782 DOI: 10.1093/bfgp/eln038] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We review different uses of the retroviral mutagenesis technology as the tool to manipulate the zebrafish genome. In addition to serving as a mutagen in a phenotype-driven forward mutagenesis screen as it was originally adapted for, retroviral insertional mutagenesis can also be exploited in reverse genetic approaches, delivering enhancer- and gene-trap vectors for the purpose of examining gene expression patterns and mutagenesis, making sensitized mutants amenable for chemical and genetic modifier screens, and producing gain-of-function mutations by epigenetically overexpressing the retroviral-inserted genes. From a technology point of view, we also summarize the recent advances in the high-throughput cloning of retroviral integration sites, a pivotal step toward identifying mutations. Lastly, we point to some potential directions that retroviral mutagenesis might take from the lessons of studying other model organisms.
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Affiliation(s)
- Li-En Jao
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Komisarczuk AZ, Topp S, Stigloher C, Kapsimali M, Bally-Cuif L, Becker TS. Enhancer detection and developmental expression of zebrafishsprouty1, a member of thefgf8synexpression group. Dev Dyn 2008; 237:2594-603. [DOI: 10.1002/dvdy.21689] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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Skromne I, Prince VE. Current perspectives in zebrafish reverse genetics: moving forward. Dev Dyn 2008; 237:861-82. [PMID: 18330930 DOI: 10.1002/dvdy.21484] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Use of the zebrafish as a model of vertebrate development and disease has expanded dramatically over the past decade. While many articles have discussed the strengths of zebrafish forward genetics (the phenotype-driven approach), there has been less emphasis on equally important and frequently used reverse genetics (the candidate gene-driven approach). Here we review both current and prospective reverse genetic techniques that are applicable to the zebrafish model. We include discussion of pharmacological approaches, popular gain-of-function and knockdown approaches, and gene targeting strategies. We consider the need for temporal and spatial control over gain/loss of gene function, and discuss available and developing techniques to achieve this end. Our goal is both to reveal the current technical advantages of the zebrafish and to highlight those areas where work is still required to allow this system to be exploited to full advantage.
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Affiliation(s)
- Isaac Skromne
- Department of Biology, University of Miami, Coral Gables, Florida 33146, USA.
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Halpern ME, Rhee J, Goll MG, Akitake CM, Parsons M, Leach SD. Gal4/UAS transgenic tools and their application to zebrafish. Zebrafish 2008; 5:97-110. [PMID: 18554173 DOI: 10.1089/zeb.2008.0530] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The ability to regulate gene expression in a cell-specific and temporally restricted manner provides a powerful means to test gene function, bypass the action of lethal genes, label subsets of cells for developmental studies, monitor subcellular structures, and target tissues for selective ablation or physiological analyses. The galactose-inducible system of yeast, mediated by the transcriptional activator Gal4 and its consensus UAS binding site, has proven to be a highly successful and versatile system for controlling transcriptional activation in Drosophila. It has also been used effectively, albeit in a more limited manner, in the mouse. While zebrafish has lagged behind other model systems in the widespread application of Gal4 transgenic approaches to modulate gene activity during development, recent technological advances are permitting rapid progress. Here we review Gal4-regulated genetic tools and discuss how they have been used in zebrafish as well as their potential drawbacks. We describe some exciting new directions, in large part afforded by the Tol2 transposition system, that are generating valuable new Gal4/UAS reagents for zebrafish research.
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Affiliation(s)
- Gerrit Begemann
- LS Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany
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Irimia M, Maeso I, Garcia-Fernàndez J. Convergent evolution of clustering of Iroquois homeobox genes across metazoans. Mol Biol Evol 2008; 25:1521-5. [PMID: 18469332 DOI: 10.1093/molbev/msn109] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vertebrate and Drosophila Iroquois genes are organized in clusters of 3 genes sharing blocks of conserved regulatory sequences. Here, we report a 3-gene cluster in the basal, preduplicative chordate amphioxus. Surprisingly, however, the origin of the amphioxus cluster is independent of those in vertebrates and drosophilids. Investigation of genomic organization of Iroquois genes in other 17 metazoan genomes revealed a fourth independent 3-gene cluster organization in polychaetes, as well as additional 2- and 4-gene clusters in other clades, in one of the most striking examples of convergence in genomic organization described so far. The recurrent independent evolution of Iroquois clusters suggests a functional importance of this organization for these genes, perhaps related to the sharing of regulatory elements. Consistent with this, comparative analysis of genomic regions flanking the 3 amphioxus Irx genes revealed several blocks of sequences, conserved for at least 100 Myr. Finally, we discuss the possible causes and implications of the convergent evolution of this genomic and regulatory organization throughout metazoans.
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