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Rouf MA, Wen L, Mahendra Y, Wang J, Zhang K, Liang S, Wang Y, Li Z, Wang Y, Wang G. The recent advances and future perspectives of genetic compensation studies in the zebrafish model. Genes Dis 2022; 10:468-479. [DOI: 10.1016/j.gendis.2021.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 10/19/2022] Open
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Salanga CM, Salanga MC. Genotype to Phenotype: CRISPR Gene Editing Reveals Genetic Compensation as a Mechanism for Phenotypic Disjunction of Morphants and Mutants. Int J Mol Sci 2021; 22:ijms22073472. [PMID: 33801686 PMCID: PMC8036752 DOI: 10.3390/ijms22073472] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022] Open
Abstract
Forward genetic screens have shown the consequences of deleterious mutations; however, they are best suited for model organisms with fast reproductive rates and large broods. Furthermore, investigators must faithfully identify changes in phenotype, even if subtle, to realize the full benefit of the screen. Reverse genetic approaches also probe genotype to phenotype relationships, except that the genetic targets are predefined. Until recently, reverse genetic approaches relied on non-genomic gene silencing or the relatively inefficient, homology-dependent gene targeting for loss-of-function generation. Fortunately, the flexibility and simplicity of the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system has revolutionized reverse genetics, allowing for the precise mutagenesis of virtually any gene in any organism at will. The successful integration of insertions/deletions (INDELs) and nonsense mutations that would, at face value, produce the expected loss-of-function phenotype, have been shown to have little to no effect, even if other methods of gene silencing demonstrate robust loss-of-function consequences. The disjunction between outcomes has raised important questions about our understanding of genotype to phenotype and highlights the capacity for compensation in the central dogma. This review describes recent studies in which genomic compensation appears to be at play, discusses the possible compensation mechanisms, and considers elements important for robust gene loss-of-function studies.
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Affiliation(s)
- Cristy M. Salanga
- Office of the Vice President for Research, Northern Arizona University, Flagstaff, AZ 86011, USA;
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Matthew C. Salanga
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
- Correspondence:
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Wong ES, Zheng D, Tan SZ, Bower NL, Garside V, Vanwalleghem G, Gaiti F, Scott E, Hogan BM, Kikuchi K, McGlinn E, Francois M, Degnan BM. Deep conservation of the enhancer regulatory code in animals. Science 2020; 370:370/6517/eaax8137. [PMID: 33154111 DOI: 10.1126/science.aax8137] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 04/29/2020] [Accepted: 09/30/2020] [Indexed: 12/15/2022]
Abstract
Interactions of transcription factors (TFs) with DNA regulatory sequences, known as enhancers, specify cell identity during animal development. Unlike TFs, the origin and evolution of enhancers has been difficult to trace. We drove zebrafish and mouse developmental transcription using enhancers from an evolutionarily distant marine sponge. Some of these sponge enhancers are located in highly conserved microsyntenic regions, including an Islet enhancer in the Islet-Scaper region. We found that Islet enhancers in humans and mice share a suite of TF binding motifs with sponges, and that they drive gene expression patterns similar to those of sponge and endogenous Islet enhancers in zebrafish. Our results suggest the existence of an ancient and conserved, yet flexible, genomic regulatory syntax that has been repeatedly co-opted into cell type-specific gene regulatory networks across the animal kingdom.
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Affiliation(s)
- Emily S Wong
- School of Biological Sciences, University of Queensland, Brisbane, Australia. .,Victor Chang Cardiac Research Institute, Sydney, Australia.,School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
| | - Dawei Zheng
- Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Siew Z Tan
- Institute for Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Neil L Bower
- Institute for Molecular Biosciences, University of Queensland, Brisbane, Australia
| | - Victoria Garside
- Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | | | - Federico Gaiti
- School of Biological Sciences, University of Queensland, Brisbane, Australia
| | - Ethan Scott
- Queensland Brain Institute, University of Queensland, Brisbane, Australia
| | - Benjamin M Hogan
- Institute for Molecular Biosciences, University of Queensland, Brisbane, Australia.,Department of Anatomy and Neuroscience and Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
| | - Kazu Kikuchi
- Victor Chang Cardiac Research Institute, Sydney, Australia
| | - Edwina McGlinn
- Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - Mathias Francois
- Institute for Molecular Biosciences, University of Queensland, Brisbane, Australia. .,Centenary Institute, David Richmond Program for Cardio-Vascular Research: Gene Regulation and Editing, School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Bernard M Degnan
- School of Biological Sciences, University of Queensland, Brisbane, Australia.
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Baeuml SW, Biechl D, Wullimann MF. Adult islet1 Expression Outlines Ventralized Derivatives Along Zebrafish Neuraxis. Front Neuroanat 2019; 13:19. [PMID: 30863287 PMCID: PMC6399416 DOI: 10.3389/fnana.2019.00019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/01/2019] [Indexed: 01/16/2023] Open
Abstract
Signals issued by dorsal roof and ventral floor plates, respectively, underlie the major patterning process of dorsalization and ventralization during vertebrate neural tube development. The ventrally produced morphogen Sonic hedgehog (SHH) is crucial for vertebrate hindbrain and spinal motor neuron development. One diagnostic gene for motor neurons is the LIM/homeodomain gene islet1, which has additional ventral expression domains extending into mid- and forebrain. In order to corroborate motor neuron development and, in particular, to improve on the identification of poorly documented zebrafish forebrain islet1 populations, we studied adult brains of transgenic islet1-GFP zebrafish (3 and 6 months). This molecular neuroanatomical analysis was supported by immunostaining these brains for tyrosine hydroxylase (TH) or choline acetyltransferase (ChAT), respectively, revealing zebrafish catecholaminergic and cholinergic neurons. The present analysis of ChAT and islet1-GFP label confirms ongoing adult expression of islet1 in zebrafish (basal plate) midbrain, hindbrain, and spinal motor neurons. In contrast, non-motor cholinergic systems lack islet1 expression. Additional presumed basal plate islet1 positive systems are described in detail, aided by TH staining which is particularly informative in the diencephalon. Finally, alar plate zebrafish forebrain systems with islet1 expression are described (i.e., thalamus, preoptic region, and subpallium). We conclude that adult zebrafish continue to express islet1 in the same brain systems as in the larva. Further, pending functional confirmation we hypothesize that the larval expression of sonic hedgehog (shh) might causally underlie much of adult islet1 expression because it explains findings beyond ventrally located systems, for example regarding shh expression in the zona limitans intrathalamica and correlated islet1-GFP expression in the thalamus.
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Affiliation(s)
- Stephan W Baeuml
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Daniela Biechl
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mario F Wullimann
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
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Simone BW, Martínez-Gálvez G, WareJoncas Z, Ekker SC. Fishing for understanding: Unlocking the zebrafish gene editor's toolbox. Methods 2018; 150:3-10. [PMID: 30076892 DOI: 10.1016/j.ymeth.2018.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/23/2018] [Accepted: 07/30/2018] [Indexed: 02/06/2023] Open
Abstract
The rapid growth of the field of gene editing can largely be attributed to the discovery and optimization of designer endonucleases. These include zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regular interspersed short palindromic repeat (CRISPR) systems including Cas9, Cas12a, and structure-guided nucleases. Zebrafish (Danio rerio) have proven to be a powerful model system for genome engineering testing and applications due to their external development, high fecundity, and ease of housing. As the zebrafish gene editing toolkit continues to grow, it is becoming increasingly important to understand when and how to utilize which of these technologies for maximum efficacy in a particular project. While CRISPR-Cas9 has brought broad attention to the field of genome engineering in recent years, designer endonucleases have been utilized in genome engineering for more than two decades. This chapter provides a brief overview of designer endonuclease and other gene editing technologies in zebrafish as well as some of their known functional benefits and limitations depending on specific project goals. Finally, selected prospects for additional gene editing tools are presented, promising additional options for directed genomic programming of this versatile animal model system.
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Affiliation(s)
- Brandon W Simone
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Zachary WareJoncas
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Stephen C Ekker
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA.
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